Merge pull request 'Fixes for Miri' (#95) from fixes-for-miri into main

Reviewed-on: #95

.github/workflows/ci.yml

@@ -1,42 +1,39 @@
-on: [push]
-
 name: ci
+on: [push, pull_request]
 
 jobs:
   check:
-    name: Check
+    name: Check build
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --release
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo check --release
 
-  msrv:
-    name: Check with MSRV
+  test:
+    name: Run Tests
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.60.0
-          override: true
-          profile: minimal
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --release
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - name: Install nextest
+        uses: taiki-e/install-action@nextest
+      - run: cargo nextest run --all-features
+      - run: cargo test --doc
+
+  msrv:
+    name: Check MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@1.65.0
+      - run: cargo check --release
 
   cross-check:
-    name: Check Cross
+    name: Check Cross-Compilation
     runs-on: ubuntu-latest
     strategy:
       matrix:
@@ -44,70 +41,32 @@ jobs:
           - armv7-unknown-linux-gnueabihf
           - thumbv7em-none-eabihf
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
-          toolchain: stable
-          target: ${{ matrix.target }}
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          use-cross: true
-          command: check
-          args: --release --target=${{ matrix.target }} --no-default-features
+          targets: "armv7-unknown-linux-gnueabihf, thumbv7em-none-eabihf"
+      - run: cargo check --release --target=${{matrix.target}} --no-default-features
 
   fmt:
-    name: Rustfmt
+    name: Check formatting
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-          override: true
-      - run: rustup component add rustfmt
-      - uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: --all -- --check
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo fmt --all -- --check
 
-  check-doc:
+  docs:
     name: Check Documentation Build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: nightly
-          override: true
-          profile: minimal
-      - uses: actions-rs/cargo@v1
-        with:
-          command: doc
-          args: --all-features
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: cargo +nightly doc --all-features --config 'build.rustdocflags=["--cfg", "docs_rs"]'
 
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-      - run: rustup component add clippy
-      - uses: actions-rs/cargo@v1
-        with:
-          command: clippy
-          args: -- -D warnings
-
-  ci:
-      if: ${{ success() }}
-      # all new jobs must be added to this list
-      needs: [check, fmt, clippy]
-      runs-on: ubuntu-latest
-      steps:
-        - name: CI succeeded
-          run: exit 0
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo clippy -- -D warnings

.idea/runConfigurations/Check.xml

@@ -0,0 +1,19 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Check" type="CargoCommandRunConfiguration" factoryName="Cargo Command">
+    <option name="command" value="check --all-features" />
+    <option name="workingDirectory" value="file://$PROJECT_DIR$" />
+    <option name="emulateTerminal" value="false" />
+    <option name="channel" value="DEFAULT" />
+    <option name="requiredFeatures" value="true" />
+    <option name="allFeatures" value="true" />
+    <option name="withSudo" value="false" />
+    <option name="buildTarget" value="REMOTE" />
+    <option name="backtrace" value="SHORT" />
+    <envs />
+    <option name="isRedirectInput" value="false" />
+    <option name="redirectInputPath" value="" />
+    <method v="2">
+      <option name="CARGO.BUILD_TASK_PROVIDER" enabled="true" />
+    </method>
+  </configuration>
+</component>

.idea/runConfigurations/Test.xml

@@ -0,0 +1,19 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Test" type="CargoCommandRunConfiguration" factoryName="Cargo Command" nameIsGenerated="true">
+    <option name="command" value="test" />
+    <option name="workingDirectory" value="file://$PROJECT_DIR$" />
+    <option name="emulateTerminal" value="false" />
+    <option name="channel" value="DEFAULT" />
+    <option name="requiredFeatures" value="true" />
+    <option name="allFeatures" value="true" />
+    <option name="withSudo" value="false" />
+    <option name="buildTarget" value="REMOTE" />
+    <option name="backtrace" value="SHORT" />
+    <envs />
+    <option name="isRedirectInput" value="false" />
+    <option name="redirectInputPath" value="" />
+    <method v="2">
+      <option name="CARGO.BUILD_TASK_PROVIDER" enabled="true" />
+    </method>
+  </configuration>
+</component>

CHANGELOG.md

@@ -8,6 +8,296 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.11.2] 2024-05-14
+
+## Fixed
+
+- Removed `defmt::Format` impl for `MetadataPduCreator` which seems to be problematic.
+
+# [v0.11.1] 2024-04-22
+
+## Fixed
+
+- The default data length for for `SpHeader` constructors where the data field length is not
+  specified is now 0.
+- The `SpHeader::new_from_fields` is public now.
+
+## Added
+
+- `SpHeader::to_vec` method.
+
+# [v0.11.0] 2024-04-16
+
+## Changed
+
+- Moved `CCSDS_HEADER_LEN` constant to the crate root.
+
+## Added
+
+- Added `SpacePacketHeader` type alias for `SpHeader` type.
+
+# [v0.11.0-rc.2] 2024-04-04
+
+## Changed
+
+- Renamed `PacketId` and `PacketSequenceCtrl` `new` method to `new_checked` and former
+  `new_const` method to `new`.
+- Renamed `tc`, `tm`, `tc_unseg` and `tm_unseg` variants for `PacketId` and `SpHeader`
+  to `new_for_tc_checked`, `new_for_tm_checked`, `new_for_unseg_tc_checked` and
+  `new_for_unseg_tm_checked`.
+- `PusTmCreator` and `PusTcCreator` now expect a regular instance of `SpHeader` instead of
+  a mutable reference.
+
+## Added
+
+- `SpHeader::new_from_apid` and `SpHeader::new_from_apid_checked` constructor.
+- `#[inline]` attribute for a lot of small functions.
+
+# [v0.11.0-rc.1] 2024-04-03
+
+Major API changes for the time API. If you are using the time API, it is strongly recommended
+to check all the API changes in the **Changed** chapter.
+
+## Fixed
+
+- CUC timestamp was fixed to include leap second corrections because it is based on the TAI
+  time reference. The default CUC time object do not implement `CcsdsTimeProvider` anymore
+  because the trait methods require cached leap second information. This task is now performed
+  by the `cuc::CucTimeWithLeapSecs` which implements the trait.
+
+## Added
+
+- `From<$EcssEnum$TY> from $TY` for the ECSS enum type definitions.
+- Added basic support conversions to the `time` library. Introduce new `chrono` and `timelib`
+  feature gate.
+- Added `CcsdsTimeProvider::timelib_date_time`.
+- Optional support for `defmt` by adding optional `defmt::Format` derives for common types.
+
+## Changed
+
+- `PusTcCreator::new_simple` now expects a valid slice for the source data instead of an optional
+  slice. For telecommands without application data, `&[]` can be passed.
+- `PusTmSecondaryHeader` constructors now expects a valid slice for the time stamp instead of an
+  optional slice.
+- Renamed `CcsdsTimeProvider::date_time` to `CcsdsTimeProvider::chrono_date_time`
+- Renamed `CcsdsTimeCodes` to `CcsdsTimeCode`
+- Renamed `cds::TimeProvider` to `cds::CdsTime`
+- Renamed `cuc::TimeProviderCcsdsEpoch` to `cuc::CucTime`
+- `UnixTimestamp` renamed to `UnixTime`
+- `UnixTime` seconds are now private and can be retrieved using the `secs` member method.
+- `UnixTime::new` renamed to `UnixTime::new_checked`.
+- `UnixTime::secs` renamed to `UnixTime::as_secs`.
+- `UnixTime` now has a nanosecond subsecond precision. The `new` constructor now expects
+   nanoseconds as the second argument.
+- Added new `UnixTime::new_subsec_millis` and `UnixTime::new_subsec_millis_checked` API
+  to still allow creating a timestamp with only millisecond subsecond resolution.
+- `CcsdsTimeProvider` now has a new `subsec_nanos` method in addition to a default
+  implementation for the `subsec_millis` method.
+- `CcsdsTimeProvider::date_time` renamed to `CcsdsTimeProvider::chrono_date_time`.
+- Added `UnixTime::MIN`, `UnixTime::MAX` and `UnixTime::EPOCH`.
+- Added `UnixTime::timelib_date_time`.
+- Error handling for ECSS and time module is more granular now, with a new
+  `DateBeforeCcsdsEpochError` error and a `DateBeforeCcsdsEpoch` enum variant for both
+  `CdsError` and `CucError`.
+- `PusTmCreator` now has two lifetimes: One for the raw source data buffer and one for the
+  raw timestamp.
+- Time API `from_now*` API renamed to `now*`.
+
+## Removed
+
+- Legacy `PusTm` and `PusTc` objects.
+
+# [v0.11.0-rc.0] 2024-03-04
+
+## Added
+
+- `From<$TY>` for the `EcssEnum$TY` ECSS enum type definitions.
+- `Sub` implementation for `UnixTimestamp` to calculate the duration between two timestamps.
+
+## Changed
+
+- `CcsdsTimeProvider` `subsecond_millis` function now returns `u16` instead of `Option<u16>`.
+- `UnixTimestamp` `subsecond_millis` function now returns `u16` instead of `Option<u16>`.
+
+# [v0.10.0] 2024-02-17
+
+## Added
+
+- Added `value` and `to_vec` methods for the `UnsignedEnum` trait. The value is returned as
+  as `u64`. Renamed former `value` method on `GenericUnsignedByteField` to `value_typed`.
+- Added `value_const` const function for `UnsignedByteField` type.
+- Added `value_typed` const functions for `GenericUnsignedByteField` and `GenericEcssEnumWrapper`.
+
+# [v0.9.0] 2024-02-07
+
+## Added
+
+- `CcsdsPacket`, `PusPacket` and `GenericPusTmSecondaryHeader` implementation for
+  `PusTmZeroCopyWriter`.
+- Additional length checks for `PusTmZeroCopyWriter`.
+
+## Changed
+
+- `PusTmZeroCopyWriter`: Added additional timestamp length argument for `new` constructor.
+
+## Fixed
+
+- Typo: `PUC_TM_MIN_HEADER_LEN` -> `PUS_TM_MIN_HEADER_LEN`
+
+# [v0.8.1] 2024-02-05
+
+## Fixed
+
+- Added `pub` visibility for `PacketSequenceCtrl::const_new`.
+
+# [v0.8.0] 2024-02-05
+
+## Added
+
+- Added `len_written` and `to_vec` methods to the `TimeWriter` trait.
+
+# [v0.7.0] 2024-02-01
+
+# [v0.7.0-beta.4] 2024-01-23
+
+## Fixed
+
+- `MetadataPduCreator`: The serialization function shifted the closure requested information
+  to the wrong position (first reserved bit) inside the raw content field.
+
+# [v0.7.0-beta.3] 2023-12-06
+
+## Added
+
+- Add `WritablePduPacket` trait which is a common trait of all CFDP PDU implementations.
+- Add `CfdpPdu` trait which exposes fields and attributes common to all CFDP PDUs.
+- Add `GenericTlv` and `WritableTlv` trait as abstractions for the various TLV types.
+
+## Fixed
+
+- Set the direction field inside the PDU header field correctly explicitely for all CFDP PDU
+  packets.
+
+## Changed
+
+- Split up `FinishedPdu`into `FinishedPduCreator` and `FinishedPduReader` to expose specialized
+  APIs.
+- Split up `MetadataPdu`into `MetadataPduCreator` and `MetadataPduReader` to expose specialized
+  APIs.
+- Cleaned up CUC time implementation. Added `width` and `counter` getter methods.
+- Renamed `SerializablePusPacket` to `WritablePusPacket`.
+- Renamed `UnsignedPfc` to `PfcUnsigned` and `RealPfc` to `PfcReal`.
+- Renamed `WritablePduPacket.written_len` and `SerializablePusPacket.len_packed` to `len_written`.
+- Introduce custom implementation of `PartialEq` for `CommonPduConfig` which only compares the
+  values for the source entity ID, destination entity ID and transaction sequence number field to
+  allow those fields to have different widths.
+- Removed the `PusError::RawDataTooShort` variant which is already covered by
+  `PusError::ByteConversionError` variant.
+- Ranamed `TlvLvError::ByteConversionError` to `TlvLvError::ByteConversion`.
+- Renamed `PusError::IncorrectCrc` to `PusError::ChecksumFailure`.
+- Some more struct variant changes for error enumerations.
+
+## Removed
+
+- `PusError::NoRawData` variant.
+- `cfdp::LenInBytes` which was not used.
+
+# [v0.7.0-beta.2] 2023-09-26
+
+## Added
+
+- `PacketId` trait impls: `Ord`, `PartialOrd` and `Hash`
+- `SerializablePusPacket` trait: Add `to_vec` method with default implementation.
+
+# [v0.7.0-beta.1] 2023-08-28
+
+- Bump `zerocopy` dependency to v0.7.0
+
+## Changed
+
+- The `Tlv` and `Lv` API return `&[u8]` instead of `Option<&[u8]>`.
+- `ByteConversionError` error variants `ToSliceTooSmall` and `FromSliceTooSmall` are struct
+  variants now. `SizeMissmatch` was removed appropriately.
+- `UnsignedByteFieldError` error variants `ValueTooLargeForWidth` and `InvalidWidth` are struct
+  variants now.
+- `TimestampError` error variant `InvalidTimeCode` is struct variant now.
+
+## Added
+
+- Added `raw_data` API for `Tlv` and `Lv` to retrieve the whole `Lv`/`Tlv` slice if the object
+  was created from a raw bytestream.
+- Added `MsgToUserTlv` helper class which wraps a regular `Tlv` and adds some useful functionality.
+- `UnsignedByteField` and `GenericUnsignedByteField` `new` methods are `const` now.
+- `PduError` variants which contained a tuple variant with multiple fields were converted to a
+  struct variant.
+
+# Added
+
+- Added `pdu_datafield_len` getter function for `PduHeader`
+
+## Removed
+
+- `SizeMissmatch` because it is not required for the `ByteConversionError` error enumeration
+  anymore.
+
+# [v0.7.0-beta.0] 2023-08-16
+
+- Moved MSRV from v1.60 to v1.61.
+
+## Changed
+
+- `PusPacket` trait: `user_data` now returns `&[u8]` instead of `Option<&[u8]>`. Empty user data
+  can simply be an empty slice.
+- Moved ECSS TC components from `tc` to `ecss.tc`.
+- Moved ECSS TM components from `tm` to `ecss.tm`.
+- Converted `PusTc` class to more specialized `PusTcCreator` and `PusTcReader`
+  classes. The old `PusTc` class is deprecated now.
+- Converted `PusTm` class to more specialized `PusTmCreator` and `PusTmReader`
+  classes. The old `PusTm` class is deprecated now.
+- Implement `Display` and `Error` for `StdTimestampError` properly.
+- Remove some redundant `Error` suffixes for enum error variants.
+- `CommonPduConfig`: `new_with_defaults` replaced by `new_with_byte_fields`.
+
+## Added
+
+- `source_data` and `app_data` API provided for PUS TM and PUS TC reader classes. These simply
+  call `user_data` but are also in line with the PUS packet standard names for those fields.
+- Added new marker trait `IsPusTelemetry` implemented by `PusTmCreator` and `PusTmReader`.
+- Added new marker trait `IsPusTelecommand` implemented by `PusTcCreator` and `PusTcReader`.
+- `metadata_param` getter method for the `MetadataPdu` object.
+- `Default` impl for CFDP `ChecksumType`
+- `Default` impl for CFDP `CommonPduConfig`
+
+## Fixed
+
+- All `MetadataGenericParam` fields are now public.
+- New setter method `set_source_and_dest_id` for `CommonPduConfig`.
+
+# [v0.6.0] 2023-07-06
+
+## Added
+
+- Added new `util` module which contains the following (new) helper modules:
+  - `UnsignedEnum` trait as an abstraction for unsigned byte fields with variable lengths. It is
+    not tied to the ECSS PFC value like the `EcssEnumeration` trait. The method to retrieve
+    the size of the unsigned enumeration in bytes is now called `size`.
+  - `GenericUnsignedByteField<TYPE>` and helper typedefs `UnsignedU8`, `UnsignedU16`, `UnsignedU32`
+    and `UnsignedU64` as helper types implementing `UnsignedEnum`
+  - `UnsignedByteField` as a type-erased helper.
+- Initial CFDP support: Added PDU packet implementation.
+- Added `SerializablePusPacket` as a generic abstraction for PUS packets which are
+  writable.
+- Added new `PusTmZeroCopyWriter` class which allows to set fields on a raw TM packet,
+  which might be more efficient that modification and re-writing a packet with the
+  `PusTm` object.
+
+## Changed
+
+- The `EcssEnumeration` now requires the `UnsignedEnum` trait and only adds the `pfc` method to it.
+- Renamed `byte_width` usages to `size` (part of new `UnsignedEnum` trait)
+- Moved `ecss::CRC_CCITT_FALSE` CRC constant to the root module. This CRC type is not just used by
+  the PUS standard, but by the CCSDS Telecommand standard and the CFDP standard as well.
+
 # [v0.5.4] 2023-02-12
 
 ## Added

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "spacepackets"
-version = "0.5.4"
+version = "0.11.1"
 edition = "2021"
-rust-version = "1.60"
+rust-version = "1.65"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]
 description = "Generic implementations for various CCSDS and ECSS packet standards"
 homepage = "https://egit.irs.uni-stuttgart.de/rust/spacepackets"
@@ -13,12 +13,19 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-zerocopy = "0.6"
 crc = "3"
-delegate = ">=0.8, <0.10"
+delegate = ">=0.8, <0.11"
+
+[dependencies.zerocopy]
+version = "0.7"
+features = ["derive"]
+
+[dependencies.thiserror]
+version = "1"
+optional = true
 
 [dependencies.num_enum]
-version = "0.5"
+version = ">0.5, <=0.7"
 default-features = false
 
 [dependencies.serde]
@@ -27,23 +34,37 @@ optional = true
 default-features = false
 features = ["derive"]
 
+[dependencies.time]
+version = "0.3"
+default-features = false
+optional = true
+
 [dependencies.chrono]
 version = "0.4"
 default-features = false
+optional = true
 
 [dependencies.num-traits]
 version = "0.2"
 default-features = false
 
-[dev-dependencies.postcard]
-version = "1.0"
+[dependencies.defmt]
+version = "0.3"
+optional = true
+
+[dev-dependencies]
+postcard = "1"
+chrono = "0.4"
 
 [features]
 default = ["std"]
-std = ["chrono/std", "chrono/clock", "alloc"]
+std = ["chrono/std", "chrono/clock", "alloc", "thiserror"]
 serde = ["dep:serde", "chrono/serde"]
 alloc = ["postcard/alloc", "chrono/alloc"]
+chrono = ["dep:chrono"]
+timelib = ["dep:time"]
+defmt = ["dep:defmt"]
 
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "doc_cfg"]
+rustdoc-args = ["--cfg", "docs_rs", "--generate-link-to-definition"]

README.md

@@ -1,6 +1,7 @@
 [![Crates.io](https://img.shields.io/crates/v/spacepackets)](https://crates.io/crates/spacepackets)
 [![docs.rs](https://img.shields.io/docsrs/spacepackets)](https://docs.rs/spacepackets)
 [![ci](https://github.com/us-irs/spacepackets-rs/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/us-irs/spacepackets-rs/actions/workflows/ci.yml)
+[![coverage](https://shields.io/endpoint?url=https://absatsw.irs.uni-stuttgart.de/projects/spacepackets/coverage-rs/latest/coverage.json)](https://absatsw.irs.uni-stuttgart.de/projects/spacepackets/coverage-rs/latest/index.html)
 
 ECSS and CCSDS Spacepackets
 ======
@@ -13,6 +14,8 @@ Currently, this includes the following components:
 
 - Space Packet implementation according to
   [CCSDS Blue Book 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf)
+- CCSDS File Delivery Protocol (CFDP) packet implementations according to
+  [CCSDS Blue Book 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf)
 - PUS Telecommand and PUS Telemetry implementation according to the
   [ECSS-E-ST-70-41C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
 - CUC (CCSDS Unsegmented Time Code) implementation according to
@@ -26,10 +29,6 @@ Currently, this includes the following components:
 
 `spacepackets` supports various runtime environments and is also suitable for `no_std` environments.
 
-It also offers optional support for [`serde`](https://serde.rs/). This allows serializing and
-deserializing them with an appropriate `serde` provider like
-[`postcard`](https://github.com/jamesmunns/postcard).
-
 ## Default features
 
  - [`std`](https://doc.rust-lang.org/std/): Enables functionality relying on the standard library.
@@ -40,8 +39,35 @@ deserializing them with an appropriate `serde` provider like
 ## Optional Features
 
  - [`serde`](https://serde.rs/): Adds `serde` support for most types by adding `Serialize` and `Deserialize` `derive`s
+ - [`chrono`](https://crates.io/crates/chrono): Add basic support for the `chrono` time library.
+ - [`timelib`](https://crates.io/crates/time): Add basic support for the `time` time library.
+ - [`defmt`](https://defmt.ferrous-systems.com/): Add support for the `defmt` by adding the
+   [`defmt::Format`](https://defmt.ferrous-systems.com/format) derive on many types.
 
 # Examples
 
 You can check the [documentation](https://docs.rs/spacepackets) of individual modules for various
 usage examples.
+
+# Coverage
+
+Coverage was generated using [`grcov`](https://github.com/mozilla/grcov). If you have not done so
+already, install the `llvm-tools-preview`:
+
+```sh
+rustup component add llvm-tools-preview
+cargo install grcov --locked
+```
+
+After that, you can simply run `coverage.py` to test the project with coverage. You can optionally
+supply the `--open` flag to open the coverage report in your webbrowser.
+
+# Miri
+
+You can run the [`miri`](https://github.com/rust-lang/miri) tool on this library to check for
+undefined behaviour (UB). This library does not use use any `unsafe` code blocks, but `miri` could
+still catch UB from used libraries.
+
+```sh
+cargo +nightly miri nextest run --all-features
+```

automation/Dockerfile

@@ -6,10 +6,23 @@ RUN apt-get update
 RUN apt-get --yes upgrade
 # tzdata is a dependency, won't install otherwise
 ARG DEBIAN_FRONTEND=noninteractive
+RUN apt-get --yes install rsync curl
 
 # set CROSS_CONTAINER_IN_CONTAINER to inform `cross` that it is executed from within a container
 ENV CROSS_CONTAINER_IN_CONTAINER=true
 
 RUN rustup install nightly && \
     rustup target add thumbv7em-none-eabihf armv7-unknown-linux-gnueabihf && \
-    rustup component add rustfmt clippy
+    rustup component add rustfmt clippy llvm-tools-preview
+
+# Get grcov
+RUN curl -sSL https://github.com/mozilla/grcov/releases/download/v0.8.19/grcov-x86_64-unknown-linux-gnu.tar.bz2 | tar -xj --directory /usr/local/bin
+# Get nextest
+RUN curl -LsSf https://get.nexte.st/latest/linux | tar zxf - -C ${CARGO_HOME:-~/.cargo}/bin
+
+# SSH stuff to allow deployment to doc server
+RUN adduser --uid 114 jenkins
+
+# Add documentation server to known hosts
+RUN echo "|1|/LzCV4BuTmTb2wKnD146l9fTKgQ=|NJJtVjvWbtRt8OYqFgcYRnMQyVw= ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBNL8ssTonYtgiR/6RRlSIK9WU1ywOcJmxFTLcEblAwH7oifZzmYq3XRfwXrgfMpylEfMFYfCU8JRqtmi19xc21A=" >> /etc/ssh/ssh_known_hosts
+RUN echo "|1|CcBvBc3EG03G+XM5rqRHs6gK/Gg=|oGeJQ+1I8NGI2THIkJsW92DpTzs= ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBNL8ssTonYtgiR/6RRlSIK9WU1ywOcJmxFTLcEblAwH7oifZzmYq3XRfwXrgfMpylEfMFYfCU8JRqtmi19xc21A=" >> /etc/ssh/ssh_known_hosts

automation/Jenkinsfile

@@ -1,52 +1,79 @@
 pipeline {
 
-    agent {
-        dockerfile {
-            dir 'automation'
-            reuseNode true
-        }
+  agent {
+    dockerfile {
+      dir 'automation'
+      reuseNode true
+      args '--network host'
     }
+  }
 
-    stages {
-        stage('Clippy') {
-            steps {
-                sh 'cargo clippy'
-            }
-        }
-        stage('Docs') {
-            steps {
-                sh 'cargo +nightly doc --all-features'
-            }
-        }
-        stage('Rustfmt') {
-            steps {
-                sh 'cargo fmt --all --check'
-            }
-        }
-        stage('Test') {
-            steps {
-                sh 'cargo test --all-features'
-            }
-        }
-        stage('Check with all features') {
-            steps {
-                sh 'cargo check --all-features'
-            }
-        }
-        stage('Check with no features') {
-            steps {
-                sh 'cargo check --no-default-features'
-            }
-        }
-        stage('Check Cross Embedded Bare Metal') {
-            steps {
-                sh 'cargo check --target thumbv7em-none-eabihf --no-default-features'
-            }
-        }
-        stage('Check Cross Embedded Linux') {
-            steps {
-                sh 'cargo check --target armv7-unknown-linux-gnueabihf'
-            }
+  stages {
+    stage('Rust Toolchain Info') {
+      steps {
+        sh 'rustc --version'
+      }
+    }
+    stage('Clippy') {
+      steps {
+        sh 'cargo clippy'
+      }
+    }
+    stage('Docs') {
+        steps {
+          sh 'cargo +nightly doc --all-features'
         }
     }
+    stage('Rustfmt') {
+        steps {
+          sh 'cargo fmt --all --check'
+        }
+    }
+    stage('Test') {
+      steps {
+        sh 'cargo nextest r --all-features'
+        sh 'cargo test --doc'
+      }
+    }
+    stage('Check with all features') {
+      steps {
+        sh 'cargo check --all-features'
+      }
+    }
+    stage('Check with no features') {
+      steps {
+        sh 'cargo check --no-default-features'
+      }
+    }
+    stage('Check Cross Embedded Bare Metal') {
+      steps {
+        sh 'cargo check --target thumbv7em-none-eabihf --no-default-features'
+      }
+    }
+    stage('Check Cross Embedded Linux') {
+      steps {
+        sh 'cargo check --target armv7-unknown-linux-gnueabihf'
+      }
+    }
+    stage('Run test with Coverage') {
+      when {
+        anyOf {
+          branch 'main';
+          branch pattern: 'cov-deployment*'
+        }
+      }
+      steps {
+        withEnv(['RUSTFLAGS=-Cinstrument-coverage', 'LLVM_PROFILE_FILE=target/coverage/%p-%m.profraw']) {
+          echo "Executing tests with coverage"
+          sh 'cargo clean'
+          sh 'cargo test --all-features'
+          sh 'grcov . -s . --binary-path ./target/debug -t html --branch --ignore-not-existing -o ./target/debug/coverage/'
+          sshagent(credentials: ['documentation-buildfix']) {
+            // Deploy to Apache webserver
+            sh 'rsync --mkpath -r --delete ./target/debug/coverage/ buildfix@documentation.irs.uni-stuttgart.de:/projects/spacepackets/coverage-rs/latest/'
+          }
+        }
+      }
+    }
+  }
 }

coverage.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+import os
+import logging
+import argparse
+import webbrowser
+
+
+_LOGGER = logging.getLogger()
+
+
+def generate_cov_report(open_report: bool, format: str):
+    logging.basicConfig(level=logging.INFO)
+    os.environ["RUSTFLAGS"] = "-Cinstrument-coverage"
+    os.environ["LLVM_PROFILE_FILE"] = "target/coverage/%p-%m.profraw"
+    _LOGGER.info("Executing tests with coverage")
+    os.system("cargo test --all-features")
+
+    out_path = "./target/debug/coverage"
+    if format == "lcov":
+        out_path = "./target/debug/lcov.info"
+    os.system(
+        f"grcov . -s . --binary-path ./target/debug/ -t {format} --branch --ignore-not-existing "
+        f"-o {out_path}"
+    )
+    if format == "lcov":
+        os.system(
+            "genhtml -o ./target/debug/coverage/ --show-details --highlight --ignore-errors source "
+            "--legend ./target/debug/lcov.info"
+        )
+    if open_report:
+        coverage_report_path = os.path.abspath("./target/debug/coverage/index.html")
+        webbrowser.open_new_tab(coverage_report_path)
+    _LOGGER.info("Done")
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Generate coverage report and optionally open it in a browser"
+    )
+    parser.add_argument(
+        "--open", action="store_true", help="Open the coverage report in a browser"
+    )
+    parser.add_argument(
+        "--format",
+        choices=["html", "lcov"],
+        default="html",
+        help="Choose report format (html or lcov)",
+    )
+    args = parser.parse_args()
+    generate_cov_report(args.open, args.format)
+
+
+if __name__ == "__main__":
+    main()

release-checklist.md

@@ -4,15 +4,20 @@ Checklist for new releases
 # Pre-Release
 
 1. Make sure any new modules are documented sufficiently enough and check docs with
-   `cargo doc --all-features --open`.
+   `cargo +nightly doc --all-features --config 'build.rustdocflags=["--cfg", "docs_rs"]' --open`.
 2. Bump version specifier in `Cargo.toml`.
 3. Update `CHANGELOG.md`: Convert `unreleased` section into version section with date and add new
    `unreleased` section.
-4. Run `cargo test --all-features`.
+4. Run `cargo test --all-features` or `cargo nextest r --all-features` together with
+   `cargo test --doc`.
 5. Run `cargo fmt` and `cargo clippy`. Check `cargo msrv` against MSRV in `Cargo.toml`.
 6. Wait for CI/CD results for EGit and Github. These also check cross-compilation for bare-metal
    targets.
 
+# Release
+
+1. `cargo publish`
+
 # Post-Release
 
 1. Create a new release on `EGit` based on the release branch.

src/cfdp/lv.rs

@@ -0,0 +1,347 @@
+//! Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
+use crate::cfdp::TlvLvError;
+use crate::ByteConversionError;
+use core::str::Utf8Error;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::string::String;
+
+pub const MIN_LV_LEN: usize = 1;
+
+/// Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
+///
+/// Please note that this class is zero-copy and does not generate a copy of the value data for
+/// both the regular [Self::new] constructor and the [Self::from_bytes] constructor.
+///
+/// # Lifetimes
+///  * `data`: If the LV is generated from a raw bytestream, this will be the lifetime of
+///    the raw bytestream. If the LV is generated from a raw slice or a similar data reference,
+///    this will be the lifetime of that data reference.
+#[derive(Debug, Copy, Clone, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct Lv<'data> {
+    data: &'data [u8],
+    // If the LV was generated from a raw bytestream, this will contain the start of the
+    // full LV.
+    pub(crate) raw_data: Option<&'data [u8]>,
+}
+
+impl PartialEq for Lv<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.data == other.data
+    }
+}
+
+pub(crate) fn generic_len_check_data_serialization(
+    buf: &[u8],
+    data_len: usize,
+    min_overhead: usize,
+) -> Result<(), ByteConversionError> {
+    if buf.len() < data_len + min_overhead {
+        return Err(ByteConversionError::ToSliceTooSmall {
+            found: buf.len(),
+            expected: data_len + min_overhead,
+        });
+    }
+    Ok(())
+}
+
+pub(crate) fn generic_len_check_deserialization(
+    buf: &[u8],
+    min_overhead: usize,
+) -> Result<(), ByteConversionError> {
+    if buf.len() < min_overhead {
+        return Err(ByteConversionError::FromSliceTooSmall {
+            found: buf.len(),
+            expected: min_overhead,
+        });
+    }
+    Ok(())
+}
+
+impl<'data> Lv<'data> {
+    #[inline]
+    pub fn new(data: &[u8]) -> Result<Lv, TlvLvError> {
+        if data.len() > u8::MAX as usize {
+            return Err(TlvLvError::DataTooLarge(data.len()));
+        }
+        Ok(Lv {
+            data,
+            raw_data: None,
+        })
+    }
+
+    /// Creates a LV with an empty value field.
+    #[inline]
+    pub fn new_empty() -> Lv<'data> {
+        Lv {
+            data: &[],
+            raw_data: None,
+        }
+    }
+
+    /// Helper function to build a string LV. This is especially useful for the file or directory
+    /// path LVs
+    #[inline]
+    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvError> {
+        Self::new(str_slice.as_bytes())
+    }
+
+    /// Helper function to build a string LV. This is especially useful for the file or directory
+    /// path LVs
+    #[cfg(feature = "std")]
+    #[inline]
+    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvError> {
+        Self::new(string.as_bytes())
+    }
+
+    /// Returns the length of the value part, not including the length byte.
+    #[inline]
+    pub fn len_value(&self) -> usize {
+        self.data.len()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    #[inline]
+    pub fn len_full(&self) -> usize {
+        self.len_value() + 1
+    }
+
+    /// Checks whether the value field is empty.
+    #[inline]
+    pub fn is_empty(&self) -> bool {
+        self.data.len() == 0
+    }
+
+    #[inline]
+    pub fn value(&self) -> &[u8] {
+        self.data
+    }
+
+    /// If the LV was generated from a raw bytestream using [Self::from_bytes], the raw start
+    /// of the LV can be retrieved with this method.
+    #[inline]
+    pub fn raw_data(&self) -> Option<&[u8]> {
+        self.raw_data
+    }
+
+    /// Convenience function to extract the value as a [str]. This is useful if the LV is
+    /// known to contain a [str], for example being a file name.
+    #[inline]
+    pub fn value_as_str(&self) -> Option<Result<&'data str, Utf8Error>> {
+        if self.is_empty() {
+            return None;
+        }
+        Some(core::str::from_utf8(self.data))
+    }
+
+    /// Writes the LV to a raw buffer. Please note that the first byte will contain the length
+    /// of the value, but the values may not exceed a length of [u8::MAX].
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        generic_len_check_data_serialization(buf, self.len_value(), MIN_LV_LEN)?;
+        Ok(self.write_to_be_bytes_no_len_check(buf))
+    }
+
+    /// Reads a LV  from a raw buffer.
+    #[inline]
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Lv<'data>, ByteConversionError> {
+        generic_len_check_deserialization(buf, MIN_LV_LEN)?;
+        Self::from_be_bytes_no_len_check(buf)
+    }
+
+    pub(crate) fn write_to_be_bytes_no_len_check(&self, buf: &mut [u8]) -> usize {
+        if self.is_empty() {
+            buf[0] = 0;
+            return MIN_LV_LEN;
+        }
+        // Length check in constructor ensures the length always has a valid value.
+        buf[0] = self.data.len() as u8;
+        buf[MIN_LV_LEN..self.data.len() + MIN_LV_LEN].copy_from_slice(self.data);
+        MIN_LV_LEN + self.data.len()
+    }
+
+    #[inline]
+    pub(crate) fn from_be_bytes_no_len_check(
+        buf: &'data [u8],
+    ) -> Result<Lv<'data>, ByteConversionError> {
+        let value_len = buf[0] as usize;
+        generic_len_check_deserialization(buf, value_len + MIN_LV_LEN)?;
+        Ok(Self {
+            data: &buf[MIN_LV_LEN..MIN_LV_LEN + value_len],
+            raw_data: Some(buf),
+        })
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use super::*;
+    use alloc::string::ToString;
+
+    use crate::cfdp::TlvLvError;
+    use crate::ByteConversionError;
+    use std::string::String;
+
+    #[test]
+    fn test_basic() {
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv_res = Lv::new(&lv_data);
+        assert!(lv_res.is_ok());
+        let lv = lv_res.unwrap();
+        assert!(!lv.value().is_empty());
+        let val = lv.value();
+        assert_eq!(val[0], 1);
+        assert_eq!(val[1], 2);
+        assert_eq!(val[2], 3);
+        assert_eq!(val[3], 4);
+        assert!(!lv.is_empty());
+        assert_eq!(lv.len_full(), 5);
+        assert_eq!(lv.len_value(), 4);
+    }
+
+    #[test]
+    fn test_empty() {
+        let lv_empty = Lv::new_empty();
+        assert_eq!(lv_empty.len_value(), 0);
+        assert_eq!(lv_empty.len_full(), 1);
+        assert!(lv_empty.is_empty());
+        let mut buf: [u8; 4] = [0xff; 4];
+        let res = lv_empty.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 1);
+        assert_eq!(buf[0], 0);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv_res = Lv::new(&lv_data);
+        assert!(lv_res.is_ok());
+        let lv = lv_res.unwrap();
+        let mut buf: [u8; 16] = [0; 16];
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 5);
+        assert_eq!(buf[0], 4);
+        assert_eq!(buf[1], 1);
+        assert_eq!(buf[2], 2);
+        assert_eq!(buf[3], 3);
+        assert_eq!(buf[4], 4);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let mut buf: [u8; 16] = [0; 16];
+        buf[0] = 4;
+        buf[1] = 1;
+        buf[2] = 2;
+        buf[3] = 3;
+        buf[4] = 4;
+        let lv = Lv::from_bytes(&buf);
+        assert!(lv.is_ok());
+        let lv = lv.unwrap();
+        assert!(!lv.is_empty());
+        assert_eq!(lv.len_value(), 4);
+        assert_eq!(lv.len_full(), 5);
+        assert!(lv.raw_data().is_some());
+        assert_eq!(lv.raw_data().unwrap(), buf);
+        let val = lv.value();
+        assert_eq!(val[0], 1);
+        assert_eq!(val[1], 2);
+        assert_eq!(val[2], 3);
+        assert_eq!(val[3], 4);
+    }
+
+    #[test]
+    fn test_deserialization_empty() {
+        let buf: [u8; 2] = [0; 2];
+        let lv_empty = Lv::from_bytes(&buf);
+        assert!(lv_empty.is_ok());
+        let lv_empty = lv_empty.unwrap();
+        assert!(lv_empty.is_empty());
+    }
+
+    #[test]
+    fn test_data_too_large() {
+        let data_big: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
+        let lv = Lv::new(&data_big);
+        assert!(lv.is_err());
+        let error = lv.unwrap_err();
+        if let TlvLvError::DataTooLarge(size) = error {
+            assert_eq!(size, u8::MAX as usize + 1);
+            assert_eq!(
+                error.to_string(),
+                "data with size 256 larger than allowed 255 bytes"
+            );
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+
+    #[test]
+    fn test_serialization_buf_too_small() {
+        let mut buf: [u8; 3] = [0; 3];
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv = Lv::new(&lv_data).unwrap();
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let ByteConversionError::ToSliceTooSmall { found, expected } = error {
+            assert_eq!(expected, 5);
+            assert_eq!(found, 3);
+        } else {
+            panic!("invalid error {}", error);
+        }
+    }
+
+    #[test]
+    fn test_deserialization_buf_too_small() {
+        let mut buf: [u8; 3] = [0; 3];
+        buf[0] = 4;
+        let res = Lv::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let ByteConversionError::FromSliceTooSmall { found, expected } = error {
+            assert_eq!(found, 3);
+            assert_eq!(expected, 5);
+        } else {
+            panic!("invalid error {}", error);
+        }
+    }
+
+    fn verify_test_str_lv(lv: Lv) {
+        let mut buf: [u8; 16] = [0; 16];
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let res = res.unwrap();
+        assert_eq!(res, 8 + 1);
+        assert_eq!(buf[0], 8);
+        assert_eq!(buf[1], b't');
+        assert_eq!(buf[2], b'e');
+        assert_eq!(buf[3], b's');
+        assert_eq!(buf[4], b't');
+        assert_eq!(buf[5], b'.');
+        assert_eq!(buf[6], b'b');
+        assert_eq!(buf[7], b'i');
+        assert_eq!(buf[8], b'n');
+    }
+    #[test]
+    fn test_str_helper() {
+        let test_str = "test.bin";
+        let str_lv = Lv::new_from_str(test_str);
+        assert!(str_lv.is_ok());
+        verify_test_str_lv(str_lv.unwrap());
+    }
+
+    #[test]
+    fn test_string_helper() {
+        let string = String::from("test.bin");
+        let str_lv = Lv::new_from_string(&string);
+        assert!(str_lv.is_ok());
+        verify_test_str_lv(str_lv.unwrap());
+    }
+}

src/cfdp/mod.rs

@@ -0,0 +1,304 @@
+//! Low-level CCSDS File Delivery Protocol (CFDP) support according to [CCSDS 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf).
+use crate::ByteConversionError;
+use core::fmt::{Display, Formatter};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub mod lv;
+pub mod pdu;
+pub mod tlv;
+
+/// This is the name of the standard this module is based on.
+pub const CFDP_VERSION_2_NAME: &str = "CCSDS 727.0-B-5";
+/// Currently, only this version is supported.
+pub const CFDP_VERSION_2: u8 = 0b001;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum PduType {
+    FileDirective = 0,
+    FileData = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum Direction {
+    TowardsReceiver = 0,
+    TowardsSender = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum TransmissionMode {
+    Acknowledged = 0,
+    Unacknowledged = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum CrcFlag {
+    NoCrc = 0,
+    WithCrc = 1,
+}
+
+impl From<bool> for CrcFlag {
+    fn from(value: bool) -> Self {
+        if value {
+            return CrcFlag::WithCrc;
+        }
+        CrcFlag::NoCrc
+    }
+}
+
+impl From<CrcFlag> for bool {
+    fn from(value: CrcFlag) -> Self {
+        if value == CrcFlag::WithCrc {
+            return true;
+        }
+        false
+    }
+}
+
+/// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum SegmentMetadataFlag {
+    NotPresent = 0,
+    Present = 1,
+}
+
+/// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum SegmentationControl {
+    NoRecordBoundaryPreservation = 0,
+    WithRecordBoundaryPreservation = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum FaultHandlerCode {
+    NoticeOfCancellation = 0b0001,
+    NoticeOfSuspension = 0b0010,
+    IgnoreError = 0b0011,
+    AbandonTransaction = 0b0100,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum ConditionCode {
+    /// This is not an error condition for which a faulty handler override can be specified
+    NoError = 0b0000,
+    PositiveAckLimitReached = 0b0001,
+    KeepAliveLimitReached = 0b0010,
+    InvalidTransmissionMode = 0b0011,
+    FilestoreRejection = 0b0100,
+    FileChecksumFailure = 0b0101,
+    FileSizeError = 0b0110,
+    NakLimitReached = 0b0111,
+    InactivityDetected = 0b1000,
+    CheckLimitReached = 0b1001,
+    UnsupportedChecksumType = 0b1011,
+    /// Not an actual fault condition for which fault handler overrides can be specified
+    SuspendRequestReceived = 0b1110,
+    /// Not an actual fault condition for which fault handler overrides can be specified
+    CancelRequestReceived = 0b1111,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum LargeFileFlag {
+    /// 32 bit maximum file size and FSS size
+    Normal = 0,
+    /// 64 bit maximum file size and FSS size
+    Large = 1,
+}
+
+/// Transaction status for the ACK PDU field according to chapter 5.2.4 of the CFDP standard.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum TransactionStatus {
+    /// Transaction is not currently active and the CFDP implementation does not retain a
+    /// transaction history.
+    Undefined = 0b00,
+    Active = 0b01,
+    /// Transaction was active in the past and was terminated.
+    Terminated = 0b10,
+    /// The CFDP implementation does retain a tranaction history, and the transaction is not and
+    /// never was active at this entity.
+    Unrecognized = 0b11,
+}
+
+/// Checksum types according to the
+/// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum ChecksumType {
+    /// Modular legacy checksum
+    Modular = 0,
+    Crc32Proximity1 = 1,
+    Crc32C = 2,
+    /// Polynomial: 0x4C11DB7. Preferred checksum for now.
+    Crc32 = 3,
+    NullChecksum = 15,
+}
+
+impl Default for ChecksumType {
+    fn default() -> Self {
+        Self::NullChecksum
+    }
+}
+
+pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum TlvLvError {
+    DataTooLarge(usize),
+    ByteConversion(ByteConversionError),
+    /// First value: Found value. Second value: Expected value if there is one.
+    InvalidTlvTypeField {
+        found: u8,
+        expected: Option<u8>,
+    },
+    /// Logically invalid value length detected. The value length may not exceed 255 bytes.
+    /// Depending on the concrete TLV type, the value length may also be logically invalid.
+    InvalidValueLength(usize),
+    /// Only applies to filestore requests and responses. Second name was missing where one is
+    /// expected.
+    SecondNameMissing,
+    /// Invalid action code for filestore requests or responses.
+    InvalidFilestoreActionCode(u8),
+}
+
+impl From<ByteConversionError> for TlvLvError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversion(value)
+    }
+}
+
+impl Display for TlvLvError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            TlvLvError::DataTooLarge(data_len) => {
+                write!(
+                    f,
+                    "data with size {} larger than allowed {} bytes",
+                    data_len,
+                    u8::MAX
+                )
+            }
+            TlvLvError::ByteConversion(e) => {
+                write!(f, "tlv or lv byte conversion: {}", e)
+            }
+            TlvLvError::InvalidTlvTypeField { found, expected } => {
+                write!(
+                    f,
+                    "invalid TLV type field, found {found}, expected {expected:?}"
+                )
+            }
+            TlvLvError::InvalidValueLength(len) => {
+                write!(f, "invalid value length {len}")
+            }
+            TlvLvError::SecondNameMissing => {
+                write!(f, "second name missing for filestore request or response")
+            }
+            TlvLvError::InvalidFilestoreActionCode(raw) => {
+                write!(f, "invalid filestore action code with raw value {raw}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for TlvLvError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            TlvLvError::ByteConversion(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[cfg(feature = "serde")]
+    use crate::tests::generic_serde_test;
+
+    #[test]
+    fn test_crc_from_bool() {
+        assert_eq!(CrcFlag::from(false), CrcFlag::NoCrc);
+    }
+
+    #[test]
+    fn test_crc_flag_to_bool() {
+        let is_true: bool = CrcFlag::WithCrc.into();
+        assert!(is_true);
+        let is_false: bool = CrcFlag::NoCrc.into();
+        assert!(!is_false);
+    }
+
+    #[test]
+    fn test_default_checksum_type() {
+        let checksum = ChecksumType::default();
+        assert_eq!(checksum, ChecksumType::NullChecksum);
+    }
+
+    #[test]
+    fn test_fault_handler_code_from_u8() {
+        let fault_handler_code_raw = FaultHandlerCode::NoticeOfSuspension as u8;
+        let fault_handler_code = FaultHandlerCode::try_from(fault_handler_code_raw).unwrap();
+        assert_eq!(fault_handler_code, FaultHandlerCode::NoticeOfSuspension);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_impl_pdu_type() {
+        generic_serde_test(PduType::FileData);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_impl_direction() {
+        generic_serde_test(Direction::TowardsReceiver);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_impl_transmission_mode() {
+        generic_serde_test(TransmissionMode::Unacknowledged);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_fault_handler_code() {
+        generic_serde_test(FaultHandlerCode::NoticeOfCancellation);
+    }
+}

src/cfdp/pdu/ack.rs

@@ -0,0 +1,335 @@
+use crate::{
+    cfdp::{ConditionCode, CrcFlag, Direction, TransactionStatus},
+    ByteConversionError,
+};
+
+use super::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, CfdpPdu, FileDirectiveType, PduError,
+    PduHeader, WritablePduPacket,
+};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+/// ACK PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.4.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct AckPdu {
+    pdu_header: PduHeader,
+    directive_code_of_acked_pdu: FileDirectiveType,
+    condition_code: ConditionCode,
+    transaction_status: TransactionStatus,
+}
+
+impl AckPdu {
+    pub fn new(
+        mut pdu_header: PduHeader,
+        directive_code_of_acked_pdu: FileDirectiveType,
+        condition_code: ConditionCode,
+        transaction_status: TransactionStatus,
+    ) -> Result<Self, PduError> {
+        if directive_code_of_acked_pdu == FileDirectiveType::EofPdu {
+            pdu_header.pdu_conf.direction = Direction::TowardsSender;
+        } else if directive_code_of_acked_pdu == FileDirectiveType::FinishedPdu {
+            pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
+        } else {
+            return Err(PduError::InvalidDirectiveType {
+                found: directive_code_of_acked_pdu as u8,
+                expected: None,
+            });
+        }
+        // Force correct direction flag.
+        let mut ack_pdu = Self {
+            pdu_header,
+            directive_code_of_acked_pdu,
+            condition_code,
+            transaction_status,
+        };
+        ack_pdu.pdu_header.pdu_datafield_len = ack_pdu.calc_pdu_datafield_len() as u16;
+        Ok(ack_pdu)
+    }
+
+    pub fn new_for_eof_pdu(
+        pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        transaction_status: TransactionStatus,
+    ) -> Self {
+        // Unwrap okay here, [new] can only fail on invalid directive codes.
+        Self::new(
+            pdu_header,
+            FileDirectiveType::EofPdu,
+            condition_code,
+            transaction_status,
+        )
+        .unwrap()
+    }
+
+    pub fn new_for_finished_pdu(
+        pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        transaction_status: TransactionStatus,
+    ) -> Self {
+        // Unwrap okay here, [new] can only fail on invalid directive codes.
+        Self::new(
+            pdu_header,
+            FileDirectiveType::FinishedPdu,
+            condition_code,
+            transaction_status,
+        )
+        .unwrap()
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn directive_code_of_acked_pdu(&self) -> FileDirectiveType {
+        self.directive_code_of_acked_pdu
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn transaction_status(&self) -> TransactionStatus {
+        self.transaction_status
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        if self.crc_flag() == CrcFlag::WithCrc {
+            return 5;
+        }
+        3
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<AckPdu, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        generic_length_checks_pdu_deserialization(buf, current_idx + 3, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::AckPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::AckPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::AckPdu,
+            });
+        }
+        current_idx += 1;
+        let acked_directive_type =
+            FileDirectiveType::try_from(buf[current_idx] >> 4).map_err(|_| {
+                PduError::InvalidDirectiveType {
+                    found: buf[current_idx],
+                    expected: None,
+                }
+            })?;
+        if acked_directive_type != FileDirectiveType::EofPdu
+            && acked_directive_type != FileDirectiveType::FinishedPdu
+        {
+            return Err(PduError::InvalidDirectiveType {
+                found: acked_directive_type as u8,
+                expected: None,
+            });
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        let transaction_status = TransactionStatus::try_from(buf[current_idx] & 0b11).unwrap();
+        Self::new(
+            pdu_header,
+            acked_directive_type,
+            condition_code,
+            transaction_status,
+        )
+    }
+}
+
+impl CfdpPdu for AckPdu {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::AckPdu)
+    }
+}
+
+impl WritablePduPacket for AckPdu {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.len_written();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::AckPdu as u8;
+        current_idx += 1;
+
+        buf[current_idx] = (self.directive_code_of_acked_pdu as u8) << 4;
+        if self.directive_code_of_acked_pdu == FileDirectiveType::FinishedPdu {
+            // This is the directive subtype code. It needs to be set to 0b0001 if the ACK PDU
+            // acknowledges a Finished PDU, and to 0b0000 otherwise.
+            buf[current_idx] |= 0b0001;
+        }
+        current_idx += 1;
+        buf[current_idx] = ((self.condition_code as u8) << 4) | (self.transaction_status as u8);
+        current_idx += 1;
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    fn len_written(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::{
+        pdu::tests::{common_pdu_conf, verify_raw_header, TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID},
+        LargeFileFlag, PduType, TransmissionMode,
+    };
+
+    use super::*;
+    #[cfg(feature = "serde")]
+    use crate::tests::generic_serde_test;
+
+    fn verify_state(ack_pdu: &AckPdu, expected_crc_flag: CrcFlag, expected_dir: Direction) {
+        assert_eq!(ack_pdu.condition_code(), ConditionCode::NoError);
+        assert_eq!(ack_pdu.transaction_status(), TransactionStatus::Active);
+
+        assert_eq!(ack_pdu.crc_flag(), expected_crc_flag);
+        assert_eq!(ack_pdu.file_flag(), LargeFileFlag::Normal);
+        assert_eq!(ack_pdu.pdu_type(), PduType::FileDirective);
+        assert_eq!(
+            ack_pdu.file_directive_type(),
+            Some(FileDirectiveType::AckPdu)
+        );
+        assert_eq!(ack_pdu.transmission_mode(), TransmissionMode::Acknowledged);
+        assert_eq!(ack_pdu.direction(), expected_dir);
+        assert_eq!(ack_pdu.source_id(), TEST_SRC_ID.into());
+        assert_eq!(ack_pdu.dest_id(), TEST_DEST_ID.into());
+        assert_eq!(ack_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
+    }
+
+    #[test]
+    fn test_basic() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let ack_pdu = AckPdu::new(
+            pdu_header,
+            FileDirectiveType::FinishedPdu,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        )
+        .expect("creating ACK PDU failed");
+        assert_eq!(
+            ack_pdu.directive_code_of_acked_pdu(),
+            FileDirectiveType::FinishedPdu
+        );
+        verify_state(&ack_pdu, CrcFlag::NoCrc, Direction::TowardsReceiver);
+    }
+
+    fn generic_serialization_test(
+        condition_code: ConditionCode,
+        transaction_status: TransactionStatus,
+    ) {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let ack_pdu = AckPdu::new_for_finished_pdu(pdu_header, condition_code, transaction_status);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = ack_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, ack_pdu.len_written());
+        verify_raw_header(ack_pdu.pdu_header(), &buf);
+
+        assert_eq!(buf[7], FileDirectiveType::AckPdu as u8);
+        assert_eq!((buf[8] >> 4) & 0b1111, FileDirectiveType::FinishedPdu as u8);
+        assert_eq!(buf[8] & 0b1111, 0b0001);
+        assert_eq!(buf[9] >> 4 & 0b1111, condition_code as u8);
+        assert_eq!(buf[9] & 0b11, transaction_status as u8);
+        assert_eq!(written, 10);
+    }
+
+    #[test]
+    fn test_serialization_no_error() {
+        generic_serialization_test(ConditionCode::NoError, TransactionStatus::Active);
+    }
+
+    #[test]
+    fn test_serialization_fs_error() {
+        generic_serialization_test(ConditionCode::FileSizeError, TransactionStatus::Terminated);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let ack_pdu = AckPdu::new_for_finished_pdu(
+            pdu_header,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        );
+        let ack_vec = ack_pdu.to_vec().unwrap();
+        let ack_deserialized =
+            AckPdu::from_bytes(&ack_vec).expect("ACK PDU deserialization failed");
+        assert_eq!(ack_deserialized, ack_pdu);
+    }
+
+    #[test]
+    fn test_with_crc() {
+        let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let ack_pdu = AckPdu::new_for_finished_pdu(
+            pdu_header,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        );
+        let ack_vec = ack_pdu.to_vec().unwrap();
+        assert_eq!(ack_vec.len(), ack_pdu.len_written());
+        assert_eq!(ack_vec.len(), 12);
+        let ack_deserialized =
+            AckPdu::from_bytes(&ack_vec).expect("ACK PDU deserialization failed");
+        assert_eq!(ack_deserialized, ack_pdu);
+    }
+
+    #[test]
+    fn test_for_eof_pdu() {
+        let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let ack_pdu = AckPdu::new_for_eof_pdu(
+            pdu_header,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        );
+        assert_eq!(
+            ack_pdu.directive_code_of_acked_pdu(),
+            FileDirectiveType::EofPdu
+        );
+        verify_state(&ack_pdu, CrcFlag::WithCrc, Direction::TowardsSender);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_ack_pdu_serialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let ack_pdu = AckPdu::new_for_eof_pdu(
+            pdu_header,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        );
+        generic_serde_test(ack_pdu);
+    }
+}

src/cfdp/pdu/eof.rs

@@ -0,0 +1,298 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::{EntityIdTlv, WritableTlv};
+use crate::cfdp::{ConditionCode, CrcFlag, Direction, LargeFileFlag};
+use crate::ByteConversionError;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use super::{CfdpPdu, WritablePduPacket};
+
+/// Finished PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.2.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct EofPdu {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    file_checksum: u32,
+    file_size: u64,
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl EofPdu {
+    pub fn new_no_error(mut pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+        // Force correct direction flag.
+        pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
+        let mut eof_pdu = Self {
+            pdu_header,
+            condition_code: ConditionCode::NoError,
+            file_checksum,
+            file_size,
+            fault_location: None,
+        };
+        eof_pdu.pdu_header.pdu_datafield_len = eof_pdu.calc_pdu_datafield_len() as u16;
+        eof_pdu
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn file_checksum(&self) -> u32 {
+        self.file_checksum
+    }
+
+    pub fn file_size(&self) -> u64 {
+        self.file_size
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        // One directive type octet, 4 bits condition code, 4 spare bits.
+        let mut len = 2 + core::mem::size_of::<u32>() + 4;
+        if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
+            len += 4;
+        }
+        if let Some(fault_location) = self.fault_location {
+            len += fault_location.len_full();
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<EofPdu, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let is_large_file = pdu_header.pdu_conf.file_flag == LargeFileFlag::Large;
+        let mut min_expected_len = 2 + 4 + 4;
+        if is_large_file {
+            min_expected_len += 4;
+        }
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::EofPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::EofPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::EofPdu,
+            });
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        current_idx += 1;
+        let file_checksum =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        current_idx += 4;
+        let (fss_field_len, file_size) =
+            read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
+        current_idx += fss_field_len;
+        let mut fault_location = None;
+        if condition_code != ConditionCode::NoError && current_idx < full_len_without_crc {
+            fault_location = Some(EntityIdTlv::from_bytes(&buf[current_idx..])?);
+        }
+        Ok(Self {
+            pdu_header,
+            condition_code,
+            file_checksum,
+            file_size,
+            fault_location,
+        })
+    }
+}
+
+impl CfdpPdu for EofPdu {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::EofPdu)
+    }
+}
+
+impl WritablePduPacket for EofPdu {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.len_written();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = (self.condition_code as u8) << 4;
+        current_idx += 1;
+        buf[current_idx..current_idx + 4].copy_from_slice(&self.file_checksum.to_be_bytes());
+        current_idx += 4;
+        current_idx += write_fss_field(
+            self.pdu_header.pdu_conf.file_flag,
+            self.file_size,
+            &mut buf[current_idx..],
+        )?;
+        if let Some(fault_location) = self.fault_location {
+            current_idx += fault_location.write_to_bytes(buf)?;
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    fn len_written(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::cfdp::pdu::tests::{
+        common_pdu_conf, verify_raw_header, TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID,
+    };
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag, PduType, TransmissionMode};
+    #[cfg(feature = "serde")]
+    use crate::tests::generic_serde_test;
+
+    fn verify_state(&eof_pdu: &EofPdu, file_flag: LargeFileFlag) {
+        assert_eq!(eof_pdu.file_checksum(), 0x01020304);
+        assert_eq!(eof_pdu.file_size(), 12);
+        assert_eq!(eof_pdu.condition_code(), ConditionCode::NoError);
+
+        assert_eq!(eof_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(eof_pdu.file_flag(), file_flag);
+        assert_eq!(eof_pdu.pdu_type(), PduType::FileDirective);
+        assert_eq!(
+            eof_pdu.file_directive_type(),
+            Some(FileDirectiveType::EofPdu)
+        );
+        assert_eq!(eof_pdu.transmission_mode(), TransmissionMode::Acknowledged);
+        assert_eq!(eof_pdu.direction(), Direction::TowardsReceiver);
+        assert_eq!(eof_pdu.source_id(), TEST_SRC_ID.into());
+        assert_eq!(eof_pdu.dest_id(), TEST_DEST_ID.into());
+        assert_eq!(eof_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
+    }
+
+    #[test]
+    fn test_basic() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        assert_eq!(eof_pdu.len_written(), pdu_header.header_len() + 2 + 4 + 4);
+        verify_state(&eof_pdu, LargeFileFlag::Normal);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = eof_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, eof_pdu.len_written());
+        verify_raw_header(eof_pdu.pdu_header(), &buf);
+        let mut current_idx = eof_pdu.pdu_header().header_len();
+        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        current_idx += 1;
+        assert_eq!(
+            (buf[current_idx] >> 4) & 0b1111,
+            ConditionCode::NoError as u8
+        );
+        current_idx += 1;
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            0x01020304
+        );
+        current_idx += 4;
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            12
+        );
+        current_idx += 4;
+        assert_eq!(current_idx, written);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        eof_pdu.write_to_bytes(&mut buf).unwrap();
+        let eof_read_back = EofPdu::from_bytes(&buf);
+        if let Err(e) = eof_read_back {
+            panic!("deserialization failed with: {e}")
+        }
+        let eof_read_back = eof_read_back.unwrap();
+        assert_eq!(eof_read_back, eof_pdu);
+    }
+
+    #[test]
+    fn test_write_to_vec() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        let written = eof_pdu.write_to_bytes(&mut buf).unwrap();
+        let pdu_vec = eof_pdu.to_vec().unwrap();
+        assert_eq!(buf[0..written], pdu_vec);
+    }
+
+    #[test]
+    fn test_with_crc() {
+        let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        let written = eof_pdu.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(written, eof_pdu.len_written());
+        let eof_from_raw = EofPdu::from_bytes(&buf).expect("creating EOF PDU failed");
+        assert_eq!(eof_from_raw, eof_pdu);
+        buf[written - 1] -= 1;
+        let crc: u16 = ((buf[written - 2] as u16) << 8) as u16 | buf[written - 1] as u16;
+        let error = EofPdu::from_bytes(&buf).unwrap_err();
+        if let PduError::ChecksumError(e) = error {
+            assert_eq!(e, crc);
+        } else {
+            panic!("expected crc error");
+        }
+    }
+
+    #[test]
+    fn test_with_large_file_flag() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Large);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        verify_state(&eof_pdu, LargeFileFlag::Large);
+        assert_eq!(eof_pdu.len_written(), pdu_header.header_len() + 2 + 8 + 4);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_eof_serde() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        generic_serde_test(eof_pdu);
+    }
+}

src/cfdp/pdu/file_data.rs

@@ -0,0 +1,485 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    PduError, PduHeader,
+};
+use crate::cfdp::{CrcFlag, LargeFileFlag, PduType, SegmentMetadataFlag};
+use crate::ByteConversionError;
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use super::{CfdpPdu, FileDirectiveType, WritablePduPacket};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum RecordContinuationState {
+    NoStartNoEnd = 0b00,
+    StartWithoutEnd = 0b01,
+    EndWithoutStart = 0b10,
+    StartAndEnd = 0b11,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct SegmentMetadata<'seg_meta> {
+    record_continuation_state: RecordContinuationState,
+    metadata: Option<&'seg_meta [u8]>,
+}
+
+impl<'seg_meta> SegmentMetadata<'seg_meta> {
+    pub fn new(
+        record_continuation_state: RecordContinuationState,
+        metadata: Option<&'seg_meta [u8]>,
+    ) -> Option<Self> {
+        if let Some(metadata) = metadata {
+            if metadata.len() > 2_usize.pow(6) - 1 {
+                return None;
+            }
+        }
+        Some(Self {
+            record_continuation_state,
+            metadata,
+        })
+    }
+
+    pub fn record_continuation_state(&self) -> RecordContinuationState {
+        self.record_continuation_state
+    }
+
+    pub fn metadata(&self) -> Option<&'seg_meta [u8]> {
+        self.metadata
+    }
+
+    pub fn written_len(&self) -> usize {
+        // Map empty metadata to 0 and slice to its length.
+        1 + self.metadata.map_or(0, |meta| meta.len())
+    }
+
+    pub(crate) fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.written_len() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.written_len(),
+            });
+        }
+        buf[0] = ((self.record_continuation_state as u8) << 6)
+            | self.metadata.map_or(0, |meta| meta.len() as u8);
+        if let Some(metadata) = self.metadata {
+            buf[1..1 + metadata.len()].copy_from_slice(metadata)
+        }
+        Ok(self.written_len())
+    }
+
+    pub(crate) fn from_bytes(buf: &'seg_meta [u8]) -> Result<Self, ByteConversionError> {
+        if buf.is_empty() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 2,
+            });
+        }
+        let mut metadata = None;
+        let seg_metadata_len = (buf[0] & 0b111111) as usize;
+        if seg_metadata_len > 0 {
+            metadata = Some(&buf[1..1 + seg_metadata_len]);
+        }
+        Ok(Self {
+            // Can't fail, only 2 bits
+            record_continuation_state: RecordContinuationState::try_from((buf[0] >> 6) & 0b11)
+                .unwrap(),
+            metadata,
+        })
+    }
+}
+
+/// File Data PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FileDataPdu<'seg_meta, 'file_data> {
+    pdu_header: PduHeader,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+    offset: u64,
+    file_data: &'file_data [u8],
+}
+
+impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
+    pub fn new_with_seg_metadata(
+        pdu_header: PduHeader,
+        segment_metadata: SegmentMetadata<'seg_meta>,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        Self::new_generic(pdu_header, Some(segment_metadata), offset, file_data)
+    }
+
+    pub fn new_no_seg_metadata(
+        pdu_header: PduHeader,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        Self::new_generic(pdu_header, None, offset, file_data)
+    }
+
+    pub fn new_generic(
+        mut pdu_header: PduHeader,
+        segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileData;
+        if segment_metadata.is_some() {
+            pdu_header.seg_metadata_flag = SegmentMetadataFlag::Present;
+        }
+        let mut pdu = Self {
+            pdu_header,
+            segment_metadata,
+            offset,
+            file_data,
+        };
+        pdu.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        let mut len = core::mem::size_of::<u32>();
+        if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
+            len += 4;
+        }
+        if self.segment_metadata.is_some() {
+            len += self.segment_metadata.as_ref().unwrap().written_len()
+        }
+        len += self.file_data.len();
+        if self.crc_flag() == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+
+    pub fn offset(&self) -> u64 {
+        self.offset
+    }
+
+    pub fn file_data(&self) -> &'file_data [u8] {
+        self.file_data
+    }
+
+    pub fn segment_metadata(&self) -> Option<&SegmentMetadata> {
+        self.segment_metadata.as_ref()
+    }
+
+    pub fn from_bytes<'buf: 'seg_meta + 'file_data>(buf: &'buf [u8]) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let min_expected_len = current_idx + core::mem::size_of::<u32>();
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let mut segment_metadata = None;
+        if pdu_header.seg_metadata_flag == SegmentMetadataFlag::Present {
+            segment_metadata = Some(SegmentMetadata::from_bytes(&buf[current_idx..])?);
+            current_idx += segment_metadata.as_ref().unwrap().written_len();
+        }
+        let (fss, offset) = read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
+        current_idx += fss;
+        if current_idx > full_len_without_crc {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: current_idx,
+                expected: full_len_without_crc,
+            }
+            .into());
+        }
+        Ok(Self {
+            pdu_header,
+            segment_metadata,
+            offset,
+            file_data: &buf[current_idx..full_len_without_crc],
+        })
+    }
+}
+impl CfdpPdu for FileDataPdu<'_, '_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
+    }
+}
+
+impl WritablePduPacket for FileDataPdu<'_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        if buf.len() < self.len_written() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_written(),
+            }
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        if self.segment_metadata.is_some() {
+            current_idx += self
+                .segment_metadata
+                .as_ref()
+                .unwrap()
+                .write_to_bytes(&mut buf[current_idx..])?;
+        }
+        current_idx += write_fss_field(
+            self.pdu_header.common_pdu_conf().file_flag,
+            self.offset,
+            &mut buf[current_idx..],
+        )?;
+        buf[current_idx..current_idx + self.file_data.len()].copy_from_slice(self.file_data);
+        current_idx += self.file_data.len();
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    fn len_written(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::cfdp::pdu::tests::{TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID};
+    use crate::cfdp::pdu::{CommonPduConfig, PduHeader};
+    use crate::cfdp::{Direction, SegmentMetadataFlag, SegmentationControl, TransmissionMode};
+    #[cfg(feature = "serde")]
+    use postcard::{from_bytes, to_allocvec};
+
+    #[test]
+    fn test_basic() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        assert_eq!(fd_pdu.file_data(), file_data);
+        assert_eq!(fd_pdu.offset(), 10);
+        assert!(fd_pdu.segment_metadata().is_none());
+        assert_eq!(
+            fd_pdu.len_written(),
+            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+        );
+
+        assert_eq!(fd_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(fd_pdu.file_flag(), LargeFileFlag::Normal);
+        assert_eq!(fd_pdu.pdu_type(), PduType::FileData);
+        assert_eq!(fd_pdu.file_directive_type(), None);
+        assert_eq!(fd_pdu.transmission_mode(), TransmissionMode::Acknowledged);
+        assert_eq!(fd_pdu.direction(), Direction::TowardsReceiver);
+        assert_eq!(fd_pdu.source_id(), TEST_SRC_ID.into());
+        assert_eq!(fd_pdu.dest_id(), TEST_DEST_ID.into());
+        assert_eq!(fd_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
+    }
+
+    #[test]
+    fn test_serialization() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let mut buf: [u8; 32] = [0; 32];
+        let res = fd_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(
+            written,
+            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+        );
+        let mut current_idx = fd_pdu.pdu_header.header_len();
+        let file_size = u32::from_be_bytes(
+            buf[fd_pdu.pdu_header.header_len()..fd_pdu.pdu_header.header_len() + 4]
+                .try_into()
+                .unwrap(),
+        );
+        current_idx += 4;
+        assert_eq!(file_size, 10);
+        assert_eq!(buf[current_idx], 1);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 2);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 3);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 4);
+    }
+
+    #[test]
+    fn test_write_to_vec() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let mut buf: [u8; 64] = [0; 64];
+        let written = fd_pdu.write_to_bytes(&mut buf).unwrap();
+        let pdu_vec = fd_pdu.to_vec().unwrap();
+        assert_eq!(buf[0..written], pdu_vec);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let mut buf: [u8; 32] = [0; 32];
+        fd_pdu.write_to_bytes(&mut buf).unwrap();
+        let fd_pdu_read_back = FileDataPdu::from_bytes(&buf);
+        assert!(fd_pdu_read_back.is_ok());
+        let fd_pdu_read_back = fd_pdu_read_back.unwrap();
+        assert_eq!(fd_pdu_read_back, fd_pdu);
+    }
+
+    #[test]
+    fn test_with_crc() {
+        let mut common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        common_conf.crc_flag = true.into();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let mut buf: [u8; 64] = [0; 64];
+        let written = fd_pdu.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(written, fd_pdu.len_written());
+        let finished_pdu_from_raw = FileDataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(finished_pdu_from_raw, fd_pdu);
+        buf[written - 1] -= 1;
+        let crc: u16 = ((buf[written - 2] as u16) << 8) | buf[written - 1] as u16;
+        let error = FileDataPdu::from_bytes(&buf).unwrap_err();
+        if let PduError::ChecksumError(e) = error {
+            assert_eq!(e, crc);
+        } else {
+            panic!("expected crc error");
+        }
+    }
+
+    #[test]
+    fn test_with_seg_metadata_serialization() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data(
+            common_conf,
+            0,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let seg_metadata: [u8; 4] = [4, 3, 2, 1];
+        let segment_meta =
+            SegmentMetadata::new(RecordContinuationState::StartAndEnd, Some(&seg_metadata))
+                .unwrap();
+        let fd_pdu = FileDataPdu::new_with_seg_metadata(pdu_header, segment_meta, 10, &file_data);
+        assert!(fd_pdu.segment_metadata().is_some());
+        assert_eq!(*fd_pdu.segment_metadata().unwrap(), segment_meta);
+        assert_eq!(
+            fd_pdu.len_written(),
+            fd_pdu.pdu_header.header_len()
+                + 1
+                + seg_metadata.len()
+                + core::mem::size_of::<u32>()
+                + 4
+        );
+        let mut buf: [u8; 32] = [0; 32];
+        fd_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing FD PDU failed");
+        let mut current_idx = fd_pdu.pdu_header.header_len();
+        assert_eq!(
+            RecordContinuationState::try_from((buf[current_idx] >> 6) & 0b11).unwrap(),
+            RecordContinuationState::StartAndEnd
+        );
+        assert_eq!((buf[current_idx] & 0b111111) as usize, seg_metadata.len());
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 4);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 3);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 2);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 1);
+        current_idx += 1;
+        // Still verify that the rest is written correctly.
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            10
+        );
+        current_idx += 4;
+        assert_eq!(buf[current_idx], 1);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 2);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 3);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 4);
+        current_idx += 1;
+        assert_eq!(current_idx, fd_pdu.len_written());
+    }
+
+    #[test]
+    fn test_with_seg_metadata_deserialization() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data(
+            common_conf,
+            0,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let seg_metadata: [u8; 4] = [4, 3, 2, 1];
+        let segment_meta =
+            SegmentMetadata::new(RecordContinuationState::StartAndEnd, Some(&seg_metadata))
+                .unwrap();
+        let fd_pdu = FileDataPdu::new_with_seg_metadata(pdu_header, segment_meta, 10, &file_data);
+        let mut buf: [u8; 32] = [0; 32];
+        fd_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing FD PDU failed");
+        let fd_pdu_read_back = FileDataPdu::from_bytes(&buf);
+        assert!(fd_pdu_read_back.is_ok());
+        let fd_pdu_read_back = fd_pdu_read_back.unwrap();
+        assert_eq!(fd_pdu_read_back, fd_pdu);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_serialization() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let output = to_allocvec(&fd_pdu).unwrap();
+        let output_converted_back: FileDataPdu = from_bytes(&output).unwrap();
+        assert_eq!(output_converted_back, fd_pdu);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_serialization_with_seg_metadata() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data(
+            common_conf,
+            0,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let seg_metadata: [u8; 4] = [4, 3, 2, 1];
+        let segment_meta =
+            SegmentMetadata::new(RecordContinuationState::StartAndEnd, Some(&seg_metadata))
+                .unwrap();
+        let fd_pdu = FileDataPdu::new_with_seg_metadata(pdu_header, segment_meta, 10, &file_data);
+        let output = to_allocvec(&fd_pdu).unwrap();
+        let output_converted_back: FileDataPdu = from_bytes(&output).unwrap();
+        assert_eq!(output_converted_back, fd_pdu);
+    }
+}

src/cfdp/pdu/finished.rs

@@ -0,0 +1,682 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::{
+    EntityIdTlv, FilestoreResponseTlv, GenericTlv, Tlv, TlvType, TlvTypeField, WritableTlv,
+};
+use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType, TlvLvError};
+use crate::ByteConversionError;
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use super::{CfdpPdu, WritablePduPacket};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum DeliveryCode {
+    Complete = 0,
+    Incomplete = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum FileStatus {
+    DiscardDeliberately = 0b00,
+    DiscardedFsRejection = 0b01,
+    Retained = 0b10,
+    Unreported = 0b11,
+}
+
+/// Finished PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct FinishedPduCreator<'fs_responses> {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    delivery_code: DeliveryCode,
+    file_status: FileStatus,
+    fs_responses:
+        &'fs_responses [FilestoreResponseTlv<'fs_responses, 'fs_responses, 'fs_responses>],
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl<'fs_responses> FinishedPduCreator<'fs_responses> {
+    /// Default finished PDU: No error (no fault location field) and no filestore responses.
+    pub fn new_default(
+        pdu_header: PduHeader,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+    ) -> Self {
+        Self::new_generic(
+            pdu_header,
+            ConditionCode::NoError,
+            delivery_code,
+            file_status,
+            &[],
+            None,
+        )
+    }
+
+    pub fn new_with_error(
+        pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+        fault_location: EntityIdTlv,
+    ) -> Self {
+        Self::new_generic(
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            &[],
+            Some(fault_location),
+        )
+    }
+
+    pub fn new_generic(
+        mut pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+        fs_responses: &'fs_responses [FilestoreResponseTlv<
+            'fs_responses,
+            'fs_responses,
+            'fs_responses,
+        >],
+        fault_location: Option<EntityIdTlv>,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileDirective;
+        // Enforce correct direction bit.
+        pdu_header.pdu_conf.direction = Direction::TowardsSender;
+        let mut finished_pdu = Self {
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            fs_responses,
+            fault_location,
+        };
+        finished_pdu.pdu_header.pdu_datafield_len = finished_pdu.calc_pdu_datafield_len() as u16;
+        finished_pdu
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn delivery_code(&self) -> DeliveryCode {
+        self.delivery_code
+    }
+
+    pub fn file_status(&self) -> FileStatus {
+        self.file_status
+    }
+
+    // If there are no filestore responses, an empty slice will be returned.
+    pub fn filestore_responses(&self) -> &[FilestoreResponseTlv<'_, '_, '_>] {
+        self.fs_responses
+    }
+
+    pub fn fault_location(&self) -> Option<EntityIdTlv> {
+        self.fault_location
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        let mut datafield_len = 2;
+        for fs_response in self.fs_responses {
+            datafield_len += fs_response.len_full();
+        }
+        if let Some(fault_location) = self.fault_location {
+            datafield_len += fault_location.len_full();
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            datafield_len += 2;
+        }
+        datafield_len
+    }
+}
+
+impl CfdpPdu for FinishedPduCreator<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::FinishedPdu)
+    }
+}
+
+impl WritablePduPacket for FinishedPduCreator<'_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.len_written();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::FinishedPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = ((self.condition_code as u8) << 4)
+            | ((self.delivery_code as u8) << 2)
+            | self.file_status as u8;
+        current_idx += 1;
+        for fs_responses in self.fs_responses {
+            current_idx += fs_responses.write_to_bytes(&mut buf[current_idx..])?;
+        }
+        if let Some(fault_location) = self.fault_location {
+            current_idx += fault_location.write_to_bytes(&mut buf[current_idx..])?;
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    fn len_written(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+}
+
+/// Helper structure to loop through all filestore responses of a read Finished PDU. It should be
+/// noted that iterators in Rust are not fallible, but the TLV creation can fail, for example if
+/// the raw TLV data is invalid for some reason. In that case, the iterator will yield [None]
+/// because there is no way to recover from this.
+///
+/// The user can accumulate the length of all TLVs yielded by the iterator and compare it against
+/// the full length of the options to check whether the iterator was able to parse all TLVs
+/// successfully.
+pub struct FilestoreResponseIterator<'buf> {
+    responses_buf: &'buf [u8],
+    current_idx: usize,
+}
+
+impl<'buf> Iterator for FilestoreResponseIterator<'buf> {
+    type Item = FilestoreResponseTlv<'buf, 'buf, 'buf>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_idx == self.responses_buf.len() {
+            return None;
+        }
+        let tlv = FilestoreResponseTlv::from_bytes(&self.responses_buf[self.current_idx..]);
+        // There are not really fallible iterators so we can't continue here..
+        if tlv.is_err() {
+            return None;
+        }
+        let tlv = tlv.unwrap();
+        self.current_idx += tlv.len_full();
+        Some(tlv)
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct FinishedPduReader<'buf> {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    delivery_code: DeliveryCode,
+    file_status: FileStatus,
+    fs_responses_raw: &'buf [u8],
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl<'buf> FinishedPduReader<'buf> {
+    /// Generates [Self] from a raw bytestream.
+    pub fn new(buf: &'buf [u8]) -> Result<Self, PduError> {
+        Self::from_bytes(buf)
+    }
+
+    /// Generates [Self] from a raw bytestream.
+    pub fn from_bytes(buf: &'buf [u8]) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let min_expected_len = current_idx + 2;
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::FinishedPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::FinishedPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::FinishedPdu,
+            });
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        // Unwrap is okay here for both of the following operations which can not fail.
+        let delivery_code = DeliveryCode::try_from((buf[current_idx] >> 2) & 0b1).unwrap();
+        let file_status = FileStatus::try_from(buf[current_idx] & 0b11).unwrap();
+        current_idx += 1;
+        let (fs_responses_raw, fault_location) =
+            Self::parse_tlv_fields(current_idx, full_len_without_crc, buf)?;
+        Ok(Self {
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            fs_responses_raw,
+            fault_location,
+        })
+    }
+
+    pub fn fs_responses_raw(&self) -> &[u8] {
+        self.fs_responses_raw
+    }
+
+    pub fn fs_responses_iter(&self) -> FilestoreResponseIterator<'_> {
+        FilestoreResponseIterator {
+            responses_buf: self.fs_responses_raw,
+            current_idx: 0,
+        }
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn delivery_code(&self) -> DeliveryCode {
+        self.delivery_code
+    }
+
+    pub fn file_status(&self) -> FileStatus {
+        self.file_status
+    }
+
+    pub fn fault_location(&self) -> Option<EntityIdTlv> {
+        self.fault_location
+    }
+
+    fn parse_tlv_fields(
+        mut current_idx: usize,
+        full_len_without_crc: usize,
+        buf: &[u8],
+    ) -> Result<(&[u8], Option<EntityIdTlv>), PduError> {
+        let mut fs_responses: &[u8] = &[];
+        let mut fault_location = None;
+        let start_of_fs_responses = current_idx;
+        // There are leftover filestore response(s) and/or a fault location field.
+        while current_idx < full_len_without_crc {
+            let next_tlv = Tlv::from_bytes(&buf[current_idx..])?;
+            match next_tlv.tlv_type_field() {
+                TlvTypeField::Standard(tlv_type) => {
+                    if tlv_type == TlvType::FilestoreResponse {
+                        current_idx += next_tlv.len_full();
+                        if current_idx == full_len_without_crc {
+                            fs_responses = &buf[start_of_fs_responses..current_idx];
+                        }
+                    } else if tlv_type == TlvType::EntityId {
+                        // At least one FS response is included.
+                        if current_idx > start_of_fs_responses {
+                            fs_responses = &buf[start_of_fs_responses..current_idx];
+                        }
+                        fault_location = Some(EntityIdTlv::from_bytes(&buf[current_idx..])?);
+                        current_idx += fault_location.as_ref().unwrap().len_full();
+                        // This is considered a configuration error: The entity ID has to be the
+                        // last TLV, everything else would break the whole handling of the packet
+                        // TLVs.
+                        if current_idx != full_len_without_crc {
+                            return Err(PduError::FormatError);
+                        }
+                    } else {
+                        return Err(TlvLvError::InvalidTlvTypeField {
+                            found: tlv_type.into(),
+                            expected: Some(TlvType::FilestoreResponse.into()),
+                        }
+                        .into());
+                    }
+                }
+                TlvTypeField::Custom(raw) => {
+                    return Err(TlvLvError::InvalidTlvTypeField {
+                        found: raw,
+                        expected: None,
+                    }
+                    .into());
+                }
+            }
+        }
+        Ok((fs_responses, fault_location))
+    }
+}
+
+impl CfdpPdu for FinishedPduReader<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::FinishedPdu)
+    }
+}
+
+impl PartialEq<FinishedPduCreator<'_>> for FinishedPduReader<'_> {
+    fn eq(&self, other: &FinishedPduCreator<'_>) -> bool {
+        self.pdu_header == other.pdu_header
+            && self.condition_code == other.condition_code
+            && self.delivery_code == other.delivery_code
+            && self.file_status == other.file_status
+            && self.fault_location == other.fault_location
+            && self
+                .fs_responses_iter()
+                .zip(other.filestore_responses().iter())
+                .all(|(a, b)| a == *b)
+    }
+}
+
+impl PartialEq<FinishedPduReader<'_>> for FinishedPduCreator<'_> {
+    fn eq(&self, other: &FinishedPduReader<'_>) -> bool {
+        other.eq(self)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::pdu::tests::{
+        common_pdu_conf, verify_raw_header, TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID,
+    };
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::tlv::FilestoreResponseTlv;
+    use crate::cfdp::{ConditionCode, CrcFlag, Direction, LargeFileFlag, TransmissionMode};
+
+    fn generic_finished_pdu(
+        crc_flag: CrcFlag,
+        fss: LargeFileFlag,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+    ) -> FinishedPduCreator<'static> {
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        FinishedPduCreator::new_default(pdu_header, delivery_code, file_status)
+    }
+
+    #[test]
+    fn test_basic() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        assert_eq!(finished_pdu.condition_code(), ConditionCode::NoError);
+        assert_eq!(
+            finished_pdu.pdu_header().pdu_conf.direction,
+            Direction::TowardsSender
+        );
+        assert_eq!(finished_pdu.delivery_code(), DeliveryCode::Complete);
+        assert_eq!(finished_pdu.file_status(), FileStatus::Retained);
+        assert_eq!(finished_pdu.filestore_responses(), &[]);
+        assert_eq!(finished_pdu.fault_location(), None);
+        assert_eq!(finished_pdu.pdu_header().pdu_datafield_len, 2);
+
+        assert_eq!(finished_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(finished_pdu.file_flag(), LargeFileFlag::Normal);
+        assert_eq!(finished_pdu.pdu_type(), PduType::FileDirective);
+        assert_eq!(
+            finished_pdu.file_directive_type(),
+            Some(FileDirectiveType::FinishedPdu)
+        );
+        assert_eq!(
+            finished_pdu.transmission_mode(),
+            TransmissionMode::Acknowledged
+        );
+        assert_eq!(finished_pdu.direction(), Direction::TowardsSender);
+        assert_eq!(finished_pdu.source_id(), TEST_SRC_ID.into());
+        assert_eq!(finished_pdu.dest_id(), TEST_DEST_ID.into());
+        assert_eq!(finished_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
+    }
+
+    fn generic_serialization_test_no_error(delivery_code: DeliveryCode, file_status: FileStatus) {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            delivery_code,
+            file_status,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let written = finished_pdu.write_to_bytes(&mut buf);
+        assert!(written.is_ok());
+        let written = written.unwrap();
+        assert_eq!(written, 9);
+        assert_eq!(written, finished_pdu.len_written());
+        assert_eq!(written, finished_pdu.pdu_header().header_len() + 2);
+        assert_eq!(
+            finished_pdu.pdu_header().pdu_conf.direction,
+            Direction::TowardsSender
+        );
+        verify_raw_header(finished_pdu.pdu_header(), &buf);
+        let mut current_idx = finished_pdu.pdu_header().header_len();
+        assert_eq!(buf[current_idx], FileDirectiveType::FinishedPdu as u8);
+        current_idx += 1;
+        assert_eq!(
+            (buf[current_idx] >> 4) & 0b1111,
+            ConditionCode::NoError as u8
+        );
+        assert_eq!((buf[current_idx] >> 2) & 0b1, delivery_code as u8);
+        assert_eq!(buf[current_idx] & 0b11, file_status as u8);
+        assert_eq!(current_idx + 1, written);
+    }
+
+    #[test]
+    fn test_serialization_simple() {
+        generic_serialization_test_no_error(DeliveryCode::Complete, FileStatus::Retained);
+    }
+
+    #[test]
+    fn test_serialization_simple_2() {
+        generic_serialization_test_no_error(
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+        );
+    }
+
+    #[test]
+    fn test_serialization_simple_3() {
+        generic_serialization_test_no_error(DeliveryCode::Incomplete, FileStatus::Unreported);
+    }
+
+    #[test]
+    fn test_write_to_vec() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let written = finished_pdu.write_to_bytes(&mut buf).unwrap();
+        let pdu_vec = finished_pdu.to_vec().unwrap();
+        assert_eq!(buf[0..written], pdu_vec);
+    }
+
+    #[test]
+    fn test_deserialization_simple() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        finished_pdu.write_to_bytes(&mut buf).unwrap();
+        let read_back = FinishedPduReader::from_bytes(&buf);
+        assert!(read_back.is_ok());
+        let read_back = read_back.unwrap();
+        assert_eq!(finished_pdu, read_back);
+        // Use all getter functions here explicitely once.
+        assert_eq!(finished_pdu.pdu_header(), read_back.pdu_header());
+        assert_eq!(finished_pdu.condition_code(), read_back.condition_code());
+        assert_eq!(finished_pdu.fault_location(), read_back.fault_location());
+        assert_eq!(finished_pdu.file_status(), read_back.file_status());
+        assert_eq!(finished_pdu.delivery_code(), read_back.delivery_code());
+    }
+
+    #[test]
+    fn test_serialization_buf_too_small() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        let mut buf: [u8; 8] = [0; 8];
+        let error = finished_pdu.write_to_bytes(&mut buf);
+        assert!(error.is_err());
+        if let PduError::ByteConversion(ByteConversionError::ToSliceTooSmall { found, expected }) =
+            error.unwrap_err()
+        {
+            assert_eq!(found, 8);
+            assert_eq!(expected, 9);
+        } else {
+            panic!("expected to_slice_too_small error");
+        }
+    }
+
+    #[test]
+    fn test_with_crc() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::WithCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let written = finished_pdu.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(written, finished_pdu.len_written());
+        let finished_pdu_from_raw = FinishedPduReader::new(&buf).unwrap();
+        assert_eq!(finished_pdu, finished_pdu_from_raw);
+        buf[written - 1] -= 1;
+        let crc: u16 = ((buf[written - 2] as u16) << 8) as u16 | buf[written - 1] as u16;
+        let error = FinishedPduReader::new(&buf).unwrap_err();
+        if let PduError::ChecksumError(e) = error {
+            assert_eq!(e, crc);
+        } else {
+            panic!("expected crc error");
+        }
+    }
+
+    #[test]
+    fn test_with_fault_location() {
+        let pdu_header =
+            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+        let finished_pdu = FinishedPduCreator::new_with_error(
+            pdu_header,
+            ConditionCode::NakLimitReached,
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+            EntityIdTlv::new(TEST_DEST_ID.into()),
+        );
+        let finished_pdu_vec = finished_pdu.to_vec().unwrap();
+        assert_eq!(finished_pdu_vec.len(), 12);
+        assert_eq!(finished_pdu_vec[9], TlvType::EntityId.into());
+        assert_eq!(finished_pdu_vec[10], 1);
+        assert_eq!(finished_pdu_vec[11], TEST_DEST_ID.value_typed());
+        assert_eq!(
+            finished_pdu.fault_location().unwrap().entity_id(),
+            &TEST_DEST_ID.into()
+        );
+    }
+
+    #[test]
+    fn test_deserialization_with_fault_location() {
+        let pdu_header =
+            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+        let entity_id_tlv = EntityIdTlv::new(TEST_DEST_ID.into());
+        let finished_pdu = FinishedPduCreator::new_with_error(
+            pdu_header,
+            ConditionCode::NakLimitReached,
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+            entity_id_tlv,
+        );
+        let finished_pdu_vec = finished_pdu.to_vec().unwrap();
+        let finished_pdu_deserialized = FinishedPduReader::from_bytes(&finished_pdu_vec).unwrap();
+        assert_eq!(finished_pdu, finished_pdu_deserialized);
+    }
+
+    #[test]
+    fn test_deserialization_with_fs_responses() {
+        let entity_id_tlv = EntityIdTlv::new(TEST_DEST_ID.into());
+        let first_name = "first.txt";
+        let first_name_lv = Lv::new_from_str(first_name).unwrap();
+        let fs_response_0 = FilestoreResponseTlv::new_no_filestore_message(
+            crate::cfdp::tlv::FilestoreActionCode::CreateFile,
+            0,
+            first_name_lv,
+            None,
+        )
+        .unwrap();
+        let fs_response_1 = FilestoreResponseTlv::new_no_filestore_message(
+            crate::cfdp::tlv::FilestoreActionCode::DeleteFile,
+            0,
+            first_name_lv,
+            None,
+        )
+        .unwrap();
+        let fs_responses = &[fs_response_0, fs_response_1];
+
+        let pdu_header =
+            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+        let finished_pdu = FinishedPduCreator::new_generic(
+            pdu_header,
+            ConditionCode::NakLimitReached,
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+            fs_responses,
+            Some(entity_id_tlv),
+        );
+        let finished_pdu_vec = finished_pdu.to_vec().unwrap();
+        let finished_pdu_deserialized = FinishedPduReader::from_bytes(&finished_pdu_vec).unwrap();
+        assert_eq!(finished_pdu_deserialized, finished_pdu);
+    }
+
+    #[test]
+    fn test_deserialization_with_fs_responses_and_fault_location() {
+        let first_name = "first.txt";
+        let first_name_lv = Lv::new_from_str(first_name).unwrap();
+        let fs_response_0 = FilestoreResponseTlv::new_no_filestore_message(
+            crate::cfdp::tlv::FilestoreActionCode::CreateFile,
+            0,
+            first_name_lv,
+            None,
+        )
+        .unwrap();
+        let fs_response_1 = FilestoreResponseTlv::new_no_filestore_message(
+            crate::cfdp::tlv::FilestoreActionCode::DeleteFile,
+            0,
+            first_name_lv,
+            None,
+        )
+        .unwrap();
+        let fs_responses = &[fs_response_0, fs_response_1];
+
+        let pdu_header =
+            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+        let finished_pdu = FinishedPduCreator::new_generic(
+            pdu_header,
+            ConditionCode::NakLimitReached,
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+            fs_responses,
+            None,
+        );
+        let finished_pdu_vec = finished_pdu.to_vec().unwrap();
+        let finished_pdu_deserialized = FinishedPduReader::from_bytes(&finished_pdu_vec).unwrap();
+        assert_eq!(finished_pdu_deserialized, finished_pdu);
+    }
+}

src/cfdp/pdu/metadata.rs

@@ -0,0 +1,770 @@
+use crate::cfdp::lv::Lv;
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::{Tlv, WritableTlv};
+use crate::cfdp::{ChecksumType, CrcFlag, Direction, LargeFileFlag, PduType};
+use crate::ByteConversionError;
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+use super::{CfdpPdu, WritablePduPacket};
+
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct MetadataGenericParams {
+    pub closure_requested: bool,
+    pub checksum_type: ChecksumType,
+    pub file_size: u64,
+}
+
+impl MetadataGenericParams {
+    pub fn new(closure_requested: bool, checksum_type: ChecksumType, file_size: u64) -> Self {
+        Self {
+            closure_requested,
+            checksum_type,
+            file_size,
+        }
+    }
+}
+
+pub fn build_metadata_opts_from_slice(
+    buf: &mut [u8],
+    tlvs: &[Tlv],
+) -> Result<usize, ByteConversionError> {
+    let mut written = 0;
+    for tlv in tlvs {
+        written += tlv.write_to_bytes(&mut buf[written..])?;
+    }
+    Ok(written)
+}
+
+#[cfg(feature = "alloc")]
+pub fn build_metadata_opts_from_vec(
+    buf: &mut [u8],
+    tlvs: &Vec<Tlv>,
+) -> Result<usize, ByteConversionError> {
+    build_metadata_opts_from_slice(buf, tlvs.as_slice())
+}
+
+/// Metadata PDU creator abstraction.
+///
+/// This abstraction exposes a specialized API for creating metadata PDUs as specified in
+/// CFDP chapter 5.2.5.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct MetadataPduCreator<'src_name, 'dest_name, 'opts> {
+    pdu_header: PduHeader,
+    metadata_params: MetadataGenericParams,
+    src_file_name: Lv<'src_name>,
+    dest_file_name: Lv<'dest_name>,
+    options: &'opts [Tlv<'opts>],
+}
+
+impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'opts> {
+    pub fn new_no_opts(
+        pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+    ) -> Self {
+        Self::new(
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            &[],
+        )
+    }
+
+    pub fn new_with_opts(
+        pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+        options: &'opts [Tlv<'opts>],
+    ) -> Self {
+        Self::new(
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options,
+        )
+    }
+
+    pub fn new(
+        mut pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+        options: &'opts [Tlv<'opts>],
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileDirective;
+        pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
+        let mut pdu = Self {
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options,
+        };
+        pdu.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    pub fn metadata_params(&self) -> &MetadataGenericParams {
+        &self.metadata_params
+    }
+
+    pub fn src_file_name(&self) -> Lv<'src_name> {
+        self.src_file_name
+    }
+
+    pub fn dest_file_name(&self) -> Lv<'dest_name> {
+        self.dest_file_name
+    }
+
+    pub fn options(&self) -> &'opts [Tlv<'opts>] {
+        self.options
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        // One directve type octet and one byte of the directive parameter field.
+        let mut len = 2;
+        if self.pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
+            len += 8;
+        } else {
+            len += 4;
+        }
+        len += self.src_file_name.len_full();
+        len += self.dest_file_name.len_full();
+        for tlv in self.options() {
+            len += tlv.len_full()
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+}
+
+impl CfdpPdu for MetadataPduCreator<'_, '_, '_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::MetadataPdu)
+    }
+}
+
+impl WritablePduPacket for MetadataPduCreator<'_, '_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.len_written();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::MetadataPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = ((self.metadata_params.closure_requested as u8) << 6)
+            | (self.metadata_params.checksum_type as u8);
+        current_idx += 1;
+        current_idx += write_fss_field(
+            self.pdu_header.common_pdu_conf().file_flag,
+            self.metadata_params.file_size,
+            &mut buf[current_idx..],
+        )?;
+        current_idx += self
+            .src_file_name
+            .write_to_be_bytes(&mut buf[current_idx..])?;
+        current_idx += self
+            .dest_file_name
+            .write_to_be_bytes(&mut buf[current_idx..])?;
+        for opt in self.options() {
+            opt.write_to_bytes(&mut buf[current_idx..current_idx + opt.len_full()])?;
+            current_idx += opt.len_full();
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    fn len_written(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+}
+
+/// Helper structure to loop through all options of a metadata PDU. It should be noted that
+/// iterators in Rust are not fallible, but the TLV creation can fail, for example if the raw TLV
+/// data is invalid for some reason. In that case, the iterator will yield [None] because there
+/// is no way to recover from this.
+///
+/// The user can accumulate the length of all TLVs yielded by the iterator and compare it against
+/// the full length of the options to check whether the iterator was able to parse all TLVs
+/// successfully.
+pub struct OptionsIter<'opts> {
+    opt_buf: &'opts [u8],
+    current_idx: usize,
+}
+
+impl<'opts> Iterator for OptionsIter<'opts> {
+    type Item = Tlv<'opts>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_idx == self.opt_buf.len() {
+            return None;
+        }
+        let tlv = Tlv::from_bytes(&self.opt_buf[self.current_idx..]);
+        // There are not really fallible iterators so we can't continue here..
+        if tlv.is_err() {
+            return None;
+        }
+        let tlv = tlv.unwrap();
+        self.current_idx += tlv.len_full();
+        Some(tlv)
+    }
+}
+
+/// Metadata PDU reader abstraction.
+///
+/// This abstraction exposes a specialized API for reading a metadata PDU with minimal copying
+/// involved.
+#[derive(Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct MetadataPduReader<'buf> {
+    pdu_header: PduHeader,
+    metadata_params: MetadataGenericParams,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    src_file_name: Lv<'buf>,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    dest_file_name: Lv<'buf>,
+    options: &'buf [u8],
+}
+
+impl<'raw> MetadataPduReader<'raw> {
+    pub fn new(buf: &'raw [u8]) -> Result<Self, PduError> {
+        Self::from_bytes(buf)
+    }
+
+    pub fn from_bytes(buf: &'raw [u8]) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let is_large_file = pdu_header.pdu_conf.file_flag == LargeFileFlag::Large;
+        // Minimal length: 1 byte + FSS (4 byte) + 2 empty LV (1 byte)
+        let mut min_expected_len = current_idx + 7;
+        if is_large_file {
+            min_expected_len += 4;
+        }
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::MetadataPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::MetadataPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::MetadataPdu,
+            });
+        }
+        current_idx += 1;
+        let (fss_len, file_size) =
+            read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx + 1..]);
+        let metadata_params = MetadataGenericParams {
+            closure_requested: ((buf[current_idx] >> 6) & 0b1) != 0,
+            checksum_type: ChecksumType::try_from(buf[current_idx] & 0b1111)
+                .map_err(|_| PduError::InvalidChecksumType(buf[current_idx] & 0b1111))?,
+            file_size,
+        };
+        current_idx += 1 + fss_len;
+        let src_file_name = Lv::from_bytes(&buf[current_idx..])?;
+        current_idx += src_file_name.len_full();
+        let dest_file_name = Lv::from_bytes(&buf[current_idx..])?;
+        current_idx += dest_file_name.len_full();
+        // All left-over bytes are options.
+        Ok(Self {
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options: &buf[current_idx..full_len_without_crc],
+        })
+    }
+
+    /// Yield an iterator which can be used to loop through all options. Returns [None] if the
+    /// options field is empty.
+    pub fn options_iter(&self) -> Option<OptionsIter<'_>> {
+        Some(OptionsIter {
+            opt_buf: self.options,
+            current_idx: 0,
+        })
+    }
+
+    pub fn options(&self) -> &'raw [u8] {
+        self.options
+    }
+
+    pub fn metadata_params(&self) -> &MetadataGenericParams {
+        &self.metadata_params
+    }
+
+    pub fn src_file_name(&self) -> Lv {
+        self.src_file_name
+    }
+
+    pub fn dest_file_name(&self) -> Lv {
+        self.dest_file_name
+    }
+}
+
+impl CfdpPdu for MetadataPduReader<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::MetadataPdu)
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use alloc::string::ToString;
+
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::pdu::metadata::{
+        build_metadata_opts_from_slice, build_metadata_opts_from_vec, MetadataGenericParams,
+        MetadataPduCreator, MetadataPduReader,
+    };
+    use crate::cfdp::pdu::tests::{
+        common_pdu_conf, verify_raw_header, TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID,
+    };
+    use crate::cfdp::pdu::{CfdpPdu, PduError, WritablePduPacket};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::tlv::{Tlv, TlvType};
+    use crate::cfdp::{
+        ChecksumType, CrcFlag, Direction, LargeFileFlag, PduType, SegmentMetadataFlag,
+        SegmentationControl, TransmissionMode,
+    };
+    use std::vec;
+
+    const SRC_FILENAME: &str = "hello-world.txt";
+    const DEST_FILENAME: &str = "hello-world2.txt";
+
+    fn generic_metadata_pdu<'opts>(
+        crc_flag: CrcFlag,
+        checksum_type: ChecksumType,
+        closure_requested: bool,
+        fss: LargeFileFlag,
+        opts: &'opts [Tlv],
+    ) -> (
+        Lv<'static>,
+        Lv<'static>,
+        MetadataPduCreator<'static, 'static, 'opts>,
+    ) {
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        let metadata_params = MetadataGenericParams::new(closure_requested, checksum_type, 0x1010);
+        let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
+        let dest_filename =
+            Lv::new_from_str(DEST_FILENAME).expect("Generating destination LV failed");
+        (
+            src_filename,
+            dest_filename,
+            MetadataPduCreator::new(
+                pdu_header,
+                metadata_params,
+                src_filename,
+                dest_filename,
+                opts,
+            ),
+        )
+    }
+
+    #[test]
+    fn test_basic() {
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Normal,
+            &[],
+        );
+        assert_eq!(
+            metadata_pdu.len_written(),
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        assert_eq!(metadata_pdu.src_file_name(), src_filename);
+        assert_eq!(metadata_pdu.dest_file_name(), dest_filename);
+        assert!(metadata_pdu.options().is_empty());
+        assert_eq!(metadata_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(metadata_pdu.file_flag(), LargeFileFlag::Normal);
+        assert_eq!(metadata_pdu.pdu_type(), PduType::FileDirective);
+        assert!(!metadata_pdu.metadata_params().closure_requested);
+        assert_eq!(
+            metadata_pdu.metadata_params().checksum_type,
+            ChecksumType::Crc32
+        );
+        assert_eq!(
+            metadata_pdu.file_directive_type(),
+            Some(FileDirectiveType::MetadataPdu)
+        );
+        assert_eq!(
+            metadata_pdu.transmission_mode(),
+            TransmissionMode::Acknowledged
+        );
+        assert_eq!(metadata_pdu.direction(), Direction::TowardsReceiver);
+        assert_eq!(metadata_pdu.source_id(), TEST_SRC_ID.into());
+        assert_eq!(metadata_pdu.dest_id(), TEST_DEST_ID.into());
+        assert_eq!(metadata_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
+    }
+
+    fn check_metadata_raw_fields(
+        metadata_pdu: &MetadataPduCreator,
+        buf: &[u8],
+        written_bytes: usize,
+        checksum_type: ChecksumType,
+        closure_requested: bool,
+        expected_src_filename: &Lv,
+        expected_dest_filename: &Lv,
+    ) {
+        verify_raw_header(metadata_pdu.pdu_header(), buf);
+        assert_eq!(
+            written_bytes,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + expected_src_filename.len_full()
+                + expected_dest_filename.len_full()
+        );
+        assert_eq!(buf[7], FileDirectiveType::MetadataPdu as u8);
+        assert_eq!(buf[8] >> 6, closure_requested as u8);
+        assert_eq!(buf[8] & 0b1111, checksum_type as u8);
+        assert_eq!(u32::from_be_bytes(buf[9..13].try_into().unwrap()), 0x1010);
+        let mut current_idx = 13;
+        let src_name_from_raw =
+            Lv::from_bytes(&buf[current_idx..]).expect("Creating source name LV failed");
+        assert_eq!(src_name_from_raw, *expected_src_filename);
+        current_idx += src_name_from_raw.len_full();
+        let dest_name_from_raw =
+            Lv::from_bytes(&buf[current_idx..]).expect("Creating dest name LV failed");
+        assert_eq!(dest_name_from_raw, *expected_dest_filename);
+        current_idx += dest_name_from_raw.len_full();
+        // No options, so no additional data here.
+        assert_eq!(current_idx, written_bytes);
+    }
+
+    #[test]
+    fn test_serialization_0() {
+        let checksum_type = ChecksumType::Crc32;
+        let closure_requested = false;
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            checksum_type,
+            closure_requested,
+            LargeFileFlag::Normal,
+            &[],
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        check_metadata_raw_fields(
+            &metadata_pdu,
+            &buf,
+            written,
+            checksum_type,
+            closure_requested,
+            &src_filename,
+            &dest_filename,
+        );
+    }
+
+    #[test]
+    fn test_serialization_1() {
+        let checksum_type = ChecksumType::Modular;
+        let closure_requested = true;
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            checksum_type,
+            closure_requested,
+            LargeFileFlag::Normal,
+            &[],
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        check_metadata_raw_fields(
+            &metadata_pdu,
+            &buf,
+            written,
+            checksum_type,
+            closure_requested,
+            &src_filename,
+            &dest_filename,
+        );
+    }
+
+    #[test]
+    fn test_write_to_vec() {
+        let (_, _, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Normal,
+            &[],
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let pdu_vec = metadata_pdu.to_vec().unwrap();
+        let written = metadata_pdu.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(buf[0..written], pdu_vec);
+    }
+
+    fn compare_read_pdu_to_written_pdu(written: &MetadataPduCreator, read: &MetadataPduReader) {
+        assert_eq!(written.metadata_params(), read.metadata_params());
+        assert_eq!(written.src_file_name(), read.src_file_name());
+        assert_eq!(written.dest_file_name(), read.dest_file_name());
+        let opts = written.options();
+        for (tlv_written, tlv_read) in opts.iter().zip(read.options_iter().unwrap()) {
+            assert_eq!(tlv_written, &tlv_read);
+        }
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let (_, _, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            true,
+            LargeFileFlag::Normal,
+            &[],
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        metadata_pdu.write_to_bytes(&mut buf).unwrap();
+        let pdu_read_back = MetadataPduReader::from_bytes(&buf);
+        assert!(pdu_read_back.is_ok());
+        let pdu_read_back = pdu_read_back.unwrap();
+        compare_read_pdu_to_written_pdu(&metadata_pdu, &pdu_read_back);
+    }
+
+    #[test]
+    fn test_with_crc_flag() {
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::WithCrc,
+            ChecksumType::Crc32,
+            true,
+            LargeFileFlag::Normal,
+            &[],
+        );
+        assert_eq!(metadata_pdu.crc_flag(), CrcFlag::WithCrc);
+        let mut buf: [u8; 64] = [0; 64];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + core::mem::size_of::<u32>()
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + 2
+        );
+        assert_eq!(written, metadata_pdu.len_written());
+        let pdu_read_back = MetadataPduReader::new(&buf).unwrap();
+        compare_read_pdu_to_written_pdu(&metadata_pdu, &pdu_read_back);
+    }
+
+    #[test]
+    fn test_with_large_file_flag() {
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Large,
+            &[],
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + core::mem::size_of::<u64>()
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        let pdu_read_back = MetadataPduReader::new(&buf).unwrap();
+        compare_read_pdu_to_written_pdu(&metadata_pdu, &pdu_read_back);
+    }
+
+    #[test]
+    fn test_opts_builders() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_slice = [tlv1, tlv2];
+        let mut buf: [u8; 32] = [0; 32];
+        let opts = build_metadata_opts_from_slice(&mut buf, &tlv_slice);
+        assert!(opts.is_ok());
+        let opts_len = opts.unwrap();
+        assert_eq!(opts_len, tlv1.len_full() + tlv2.len_full());
+        let tlv1_conv_back = Tlv::from_bytes(&buf).unwrap();
+        assert_eq!(tlv1_conv_back, tlv1);
+        let tlv2_conv_back = Tlv::from_bytes(&buf[tlv1_conv_back.len_full()..]).unwrap();
+        assert_eq!(tlv2_conv_back, tlv2);
+    }
+
+    #[test]
+    fn test_opts_builders_from_vec() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_vec = vec![tlv1, tlv2];
+        let mut buf: [u8; 32] = [0; 32];
+        let opts = build_metadata_opts_from_vec(&mut buf, &tlv_vec);
+        assert!(opts.is_ok());
+        let opts_len = opts.unwrap();
+        assert_eq!(opts_len, tlv1.len_full() + tlv2.len_full());
+        let tlv1_conv_back = Tlv::from_bytes(&buf).unwrap();
+        assert_eq!(tlv1_conv_back, tlv1);
+        let tlv2_conv_back = Tlv::from_bytes(&buf[tlv1_conv_back.len_full()..]).unwrap();
+        assert_eq!(tlv2_conv_back, tlv2);
+    }
+
+    #[test]
+    fn test_with_opts() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_vec = vec![tlv1, tlv2];
+        let opts_len = tlv1.len_full() + tlv2.len_full();
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Normal,
+            &tlv_vec,
+        );
+        let mut buf: [u8; 128] = [0; 128];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + opts_len
+        );
+        let pdu_read_back = MetadataPduReader::from_bytes(&buf).unwrap();
+        compare_read_pdu_to_written_pdu(&metadata_pdu, &pdu_read_back);
+        let opts_iter = pdu_read_back.options_iter();
+        assert!(opts_iter.is_some());
+        let opts_iter = opts_iter.unwrap();
+        let mut accumulated_len = 0;
+        for (idx, opt) in opts_iter.enumerate() {
+            assert_eq!(tlv_vec[idx], opt);
+            accumulated_len += opt.len_full();
+        }
+        assert_eq!(accumulated_len, pdu_read_back.options().len());
+    }
+
+    #[test]
+    fn test_invalid_directive_code() {
+        let (_, _, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            true,
+            LargeFileFlag::Large,
+            &[],
+        );
+        let mut metadata_vec = metadata_pdu.to_vec().unwrap();
+        metadata_vec[7] = 0xff;
+        let metadata_error = MetadataPduReader::from_bytes(&metadata_vec);
+        assert!(metadata_error.is_err());
+        let error = metadata_error.unwrap_err();
+        if let PduError::InvalidDirectiveType { found, expected } = error {
+            assert_eq!(found, 0xff);
+            assert_eq!(expected, Some(FileDirectiveType::MetadataPdu));
+            assert_eq!(
+                error.to_string(),
+                "invalid directive type value 255, expected Some(MetadataPdu)"
+            );
+        } else {
+            panic!("Expected InvalidDirectiveType error, got {:?}", error);
+        }
+    }
+
+    #[test]
+    fn test_wrong_directive_code() {
+        let (_, _, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Large,
+            &[],
+        );
+        let mut metadata_vec = metadata_pdu.to_vec().unwrap();
+        metadata_vec[7] = FileDirectiveType::EofPdu as u8;
+        let metadata_error = MetadataPduReader::from_bytes(&metadata_vec);
+        assert!(metadata_error.is_err());
+        let error = metadata_error.unwrap_err();
+        if let PduError::WrongDirectiveType { found, expected } = error {
+            assert_eq!(found, FileDirectiveType::EofPdu);
+            assert_eq!(expected, FileDirectiveType::MetadataPdu);
+            assert_eq!(
+                error.to_string(),
+                "found directive type EofPdu, expected MetadataPdu"
+            );
+        } else {
+            panic!("Expected InvalidDirectiveType error, got {:?}", error);
+        }
+    }
+    #[test]
+    fn test_corrects_pdu_header() {
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        );
+        let metadata_params = MetadataGenericParams::new(false, ChecksumType::Crc32, 10);
+        let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
+        let dest_filename =
+            Lv::new_from_str(DEST_FILENAME).expect("Generating destination LV failed");
+        let metadata_pdu = MetadataPduCreator::new_no_opts(
+            pdu_header,
+            metadata_params,
+            src_filename,
+            dest_filename,
+        );
+        assert_eq!(metadata_pdu.pdu_header().pdu_type(), PduType::FileDirective);
+    }
+}

src/cfdp/pdu/nak.rs

@@ -0,0 +1,806 @@
+use crate::{
+    cfdp::{CrcFlag, Direction, LargeFileFlag},
+    ByteConversionError,
+};
+use core::{marker::PhantomData, mem::size_of};
+
+use super::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, CfdpPdu, FileDirectiveType, PduError,
+    PduHeader, WritablePduPacket,
+};
+
+/// Helper type to encapsulate both normal file size segment requests and large file size segment
+/// requests.
+#[derive(Debug, PartialEq, Eq, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum SegmentRequests<'a> {
+    U32Pairs(&'a [(u32, u32)]),
+    U64Pairs(&'a [(u64, u64)]),
+}
+
+impl SegmentRequests<'_> {
+    pub fn is_empty(&self) -> bool {
+        match self {
+            SegmentRequests::U32Pairs(pairs) => pairs.is_empty(),
+            SegmentRequests::U64Pairs(pairs) => pairs.is_empty(),
+        }
+    }
+}
+
+/// NAK PDU abstraction specialized in the creation of NAK PDUs.
+///
+/// It exposes a specialized API which simplifies to generate these NAK PDUs with the
+/// format according to CFDP chapter 5.2.6.
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct NakPduCreator<'seg_reqs> {
+    pdu_header: PduHeader,
+    start_of_scope: u64,
+    end_of_scope: u64,
+    segment_requests: Option<SegmentRequests<'seg_reqs>>,
+}
+
+impl<'seg_reqs> NakPduCreator<'seg_reqs> {
+    /// Please note that the start of scope and the end of scope need to be smaller or equal
+    /// to [u32::MAX] if the large file flag of the passed PDU configuration is
+    /// [LargeFileFlag::Normal].
+    ///
+    /// ## Errrors
+    ///
+    pub fn new_no_segment_requests(
+        pdu_header: PduHeader,
+        start_of_scope: u64,
+        end_of_scope: u64,
+    ) -> Result<NakPduCreator<'seg_reqs>, PduError> {
+        Self::new_generic(pdu_header, start_of_scope, end_of_scope, None)
+    }
+
+    /// Default constructor for normal file sizes.
+    pub fn new(
+        pdu_header: PduHeader,
+        start_of_scope: u32,
+        end_of_scope: u32,
+        segment_requests: &'seg_reqs [(u32, u32)],
+    ) -> Result<NakPduCreator, PduError> {
+        let mut passed_segment_requests = None;
+        if !segment_requests.is_empty() {
+            passed_segment_requests = Some(SegmentRequests::U32Pairs(segment_requests));
+        }
+        Self::new_generic(
+            pdu_header,
+            start_of_scope.into(),
+            end_of_scope.into(),
+            passed_segment_requests,
+        )
+    }
+
+    pub fn new_large_file_size(
+        pdu_header: PduHeader,
+        start_of_scope: u64,
+        end_of_scope: u64,
+        segment_requests: &'seg_reqs [(u64, u64)],
+    ) -> Result<NakPduCreator, PduError> {
+        let mut passed_segment_requests = None;
+        if !segment_requests.is_empty() {
+            passed_segment_requests = Some(SegmentRequests::U64Pairs(segment_requests));
+        }
+        Self::new_generic(
+            pdu_header,
+            start_of_scope,
+            end_of_scope,
+            passed_segment_requests,
+        )
+    }
+
+    fn new_generic(
+        mut pdu_header: PduHeader,
+        start_of_scope: u64,
+        end_of_scope: u64,
+        segment_requests: Option<SegmentRequests<'seg_reqs>>,
+    ) -> Result<NakPduCreator, PduError> {
+        // Force correct direction flag.
+        pdu_header.pdu_conf.direction = Direction::TowardsSender;
+        if let Some(ref segment_requests) = segment_requests {
+            match segment_requests {
+                SegmentRequests::U32Pairs(_) => {
+                    if start_of_scope > u32::MAX as u64 || end_of_scope > u32::MAX as u64 {
+                        return Err(PduError::InvalidStartOrEndOfScopeValue);
+                    }
+                    pdu_header.pdu_conf.file_flag = LargeFileFlag::Normal;
+                }
+                SegmentRequests::U64Pairs(_) => {
+                    pdu_header.pdu_conf.file_flag = LargeFileFlag::Large;
+                }
+            }
+        };
+        let mut nak_pdu = Self {
+            pdu_header,
+            start_of_scope,
+            end_of_scope,
+            segment_requests,
+        };
+        nak_pdu.pdu_header.pdu_datafield_len = nak_pdu.calc_pdu_datafield_len() as u16;
+        Ok(nak_pdu)
+    }
+
+    pub fn start_of_scope(&self) -> u64 {
+        self.start_of_scope
+    }
+
+    pub fn end_of_scope(&self) -> u64 {
+        self.end_of_scope
+    }
+
+    pub fn segment_requests(&self) -> Option<&SegmentRequests> {
+        self.segment_requests.as_ref()
+    }
+
+    pub fn num_segment_reqs(&self) -> usize {
+        match &self.segment_requests {
+            Some(seg_reqs) => match seg_reqs {
+                SegmentRequests::U32Pairs(pairs) => pairs.len(),
+                SegmentRequests::U64Pairs(pairs) => pairs.len(),
+            },
+            None => 0,
+        }
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        let mut datafield_len = 1;
+        if self.file_flag() == LargeFileFlag::Normal {
+            datafield_len += 8;
+            datafield_len += self.num_segment_reqs() * 8;
+        } else {
+            datafield_len += 16;
+            datafield_len += self.num_segment_reqs() * 16;
+        }
+        if self.crc_flag() == CrcFlag::WithCrc {
+            datafield_len += 2;
+        }
+        datafield_len
+    }
+}
+
+impl CfdpPdu for NakPduCreator<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::NakPdu)
+    }
+}
+
+impl WritablePduPacket for NakPduCreator<'_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.len_written();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::NakPdu as u8;
+        current_idx += 1;
+
+        let mut write_start_end_of_scope_normal = || {
+            let start_of_scope = u32::try_from(self.start_of_scope).unwrap();
+            let end_of_scope = u32::try_from(self.end_of_scope).unwrap();
+            buf[current_idx..current_idx + 4].copy_from_slice(&start_of_scope.to_be_bytes());
+            current_idx += 4;
+            buf[current_idx..current_idx + 4].copy_from_slice(&end_of_scope.to_be_bytes());
+            current_idx += 4;
+        };
+        if let Some(ref seg_reqs) = self.segment_requests {
+            match seg_reqs {
+                SegmentRequests::U32Pairs(pairs) => {
+                    // Unwrap is okay here, the API should prevent invalid values which would trigger a
+                    // panic here.
+                    write_start_end_of_scope_normal();
+                    for (next_start_offset, next_end_offset) in *pairs {
+                        buf[current_idx..current_idx + 4]
+                            .copy_from_slice(&next_start_offset.to_be_bytes());
+                        current_idx += 4;
+                        buf[current_idx..current_idx + 4]
+                            .copy_from_slice(&next_end_offset.to_be_bytes());
+                        current_idx += 4;
+                    }
+                }
+                SegmentRequests::U64Pairs(pairs) => {
+                    buf[current_idx..current_idx + 8]
+                        .copy_from_slice(&self.start_of_scope.to_be_bytes());
+                    current_idx += 8;
+                    buf[current_idx..current_idx + 8]
+                        .copy_from_slice(&self.end_of_scope.to_be_bytes());
+                    current_idx += 8;
+                    for (next_start_offset, next_end_offset) in *pairs {
+                        buf[current_idx..current_idx + 8]
+                            .copy_from_slice(&next_start_offset.to_be_bytes());
+                        current_idx += 8;
+                        buf[current_idx..current_idx + 8]
+                            .copy_from_slice(&next_end_offset.to_be_bytes());
+                        current_idx += 8;
+                    }
+                }
+            }
+        } else {
+            write_start_end_of_scope_normal();
+        }
+
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    fn len_written(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+}
+
+/// Special iterator type for the NAK PDU which allows to iterate over both normal and large file
+/// segment requests.
+#[derive(Debug)]
+pub struct SegmentRequestIter<'a, T> {
+    seq_req_raw: &'a [u8],
+    current_idx: usize,
+    phantom: core::marker::PhantomData<T>,
+}
+
+pub trait SegReqFromBytes {
+    fn from_bytes(bytes: &[u8]) -> Self;
+}
+
+impl SegReqFromBytes for u32 {
+    fn from_bytes(bytes: &[u8]) -> u32 {
+        u32::from_be_bytes(bytes.try_into().unwrap())
+    }
+}
+
+impl SegReqFromBytes for u64 {
+    fn from_bytes(bytes: &[u8]) -> u64 {
+        u64::from_be_bytes(bytes.try_into().unwrap())
+    }
+}
+
+impl<'a, T> Iterator for SegmentRequestIter<'a, T>
+where
+    T: SegReqFromBytes,
+{
+    type Item = (T, T);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let value = self.next_at_offset(self.current_idx);
+        self.current_idx += 2 * size_of::<T>();
+        value
+    }
+}
+
+impl<'a, 'b> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'b, u32> {
+    fn eq(&self, other: &SegmentRequests) -> bool {
+        match other {
+            SegmentRequests::U32Pairs(pairs) => self.compare_pairs(pairs),
+            SegmentRequests::U64Pairs(pairs) => {
+                if pairs.is_empty() && self.seq_req_raw.is_empty() {
+                    return true;
+                }
+                false
+            }
+        }
+    }
+}
+
+impl<'a, 'b> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'b, u64> {
+    fn eq(&self, other: &SegmentRequests) -> bool {
+        match other {
+            SegmentRequests::U32Pairs(pairs) => {
+                if pairs.is_empty() && self.seq_req_raw.is_empty() {
+                    return true;
+                }
+                false
+            }
+            SegmentRequests::U64Pairs(pairs) => self.compare_pairs(pairs),
+        }
+    }
+}
+
+impl<'a, T> SegmentRequestIter<'a, T>
+where
+    T: SegReqFromBytes + PartialEq,
+{
+    fn compare_pairs(&self, pairs: &[(T, T)]) -> bool {
+        if pairs.is_empty() && self.seq_req_raw.is_empty() {
+            return true;
+        }
+        let size = size_of::<T>();
+        if pairs.len() * 2 * size != self.seq_req_raw.len() {
+            return false;
+        }
+
+        for (i, pair) in pairs.iter().enumerate() {
+            let next_val = self.next_at_offset(i * 2 * size).unwrap();
+            if next_val != *pair {
+                return false;
+            }
+        }
+
+        true
+    }
+}
+
+impl<T: SegReqFromBytes> SegmentRequestIter<'_, T> {
+    fn next_at_offset(&self, mut offset: usize) -> Option<(T, T)> {
+        if offset + size_of::<T>() * 2 > self.seq_req_raw.len() {
+            return None;
+        }
+
+        let start_offset = T::from_bytes(&self.seq_req_raw[offset..offset + size_of::<T>()]);
+        offset += size_of::<T>();
+
+        let end_offset = T::from_bytes(&self.seq_req_raw[offset..offset + size_of::<T>()]);
+        Some((start_offset, end_offset))
+    }
+}
+
+/// NAK PDU abstraction specialized in the reading NAK PDUs from a raw bytestream.
+///
+/// This is a zero-copy class where the segment requests can be read using a special iterator
+/// API without the need to copy them.
+///
+/// The NAK format is expected to be conforming to CFDP chapter 5.2.6.
+#[derive(Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct NakPduReader<'seg_reqs> {
+    pdu_header: PduHeader,
+    start_of_scope: u64,
+    end_of_scope: u64,
+    seg_reqs_raw: &'seg_reqs [u8],
+}
+
+impl CfdpPdu for NakPduReader<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::NakPdu)
+    }
+}
+
+impl<'seg_reqs> NakPduReader<'seg_reqs> {
+    pub fn new(buf: &'seg_reqs [u8]) -> Result<NakPduReader, PduError> {
+        Self::from_bytes(buf)
+    }
+
+    pub fn from_bytes(buf: &'seg_reqs [u8]) -> Result<NakPduReader, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        // Minimum length of 9: 1 byte directive field and start and end of scope for normal file
+        // size.
+        generic_length_checks_pdu_deserialization(buf, 9, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::NakPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::NakPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::AckPdu,
+            });
+        }
+        current_idx += 1;
+        let start_of_scope;
+        let end_of_scope;
+        if pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
+            if current_idx + 16 > buf.len() {
+                return Err(PduError::ByteConversion(
+                    ByteConversionError::FromSliceTooSmall {
+                        found: buf.len(),
+                        expected: current_idx + 16,
+                    },
+                ));
+            }
+            start_of_scope =
+                u64::from_be_bytes(buf[current_idx..current_idx + 8].try_into().unwrap());
+            current_idx += 8;
+            end_of_scope =
+                u64::from_be_bytes(buf[current_idx..current_idx + 8].try_into().unwrap());
+            current_idx += 8;
+        } else {
+            start_of_scope =
+                u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()) as u64;
+            current_idx += 4;
+            end_of_scope =
+                u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()) as u64;
+            current_idx += 4;
+        }
+        Ok(Self {
+            pdu_header,
+            start_of_scope,
+            end_of_scope,
+            seg_reqs_raw: &buf[current_idx..full_len_without_crc],
+        })
+    }
+
+    pub fn start_of_scope(&self) -> u64 {
+        self.start_of_scope
+    }
+
+    pub fn end_of_scope(&self) -> u64 {
+        self.end_of_scope
+    }
+
+    pub fn num_segment_reqs(&self) -> usize {
+        if self.seg_reqs_raw.is_empty() {
+            return 0;
+        }
+        if self.file_flag() == LargeFileFlag::Normal {
+            self.seg_reqs_raw.len() / 8
+        } else {
+            self.seg_reqs_raw.len() / 16
+        }
+    }
+
+    /// This function returns [None] if this NAK PDUs contains segment requests for a large file.
+    pub fn get_normal_segment_requests_iterator(&self) -> Option<SegmentRequestIter<'_, u32>> {
+        if self.file_flag() == LargeFileFlag::Large {
+            return None;
+        }
+        Some(SegmentRequestIter {
+            seq_req_raw: self.seg_reqs_raw,
+            current_idx: 0,
+            phantom: PhantomData,
+        })
+    }
+
+    /// This function returns [None] if this NAK PDUs contains segment requests for a normal file.
+    pub fn get_large_segment_requests_iterator(&self) -> Option<SegmentRequestIter<'_, u64>> {
+        if self.file_flag() == LargeFileFlag::Normal {
+            return None;
+        }
+        Some(SegmentRequestIter {
+            seq_req_raw: self.seg_reqs_raw,
+            current_idx: 0,
+            phantom: PhantomData,
+        })
+    }
+}
+
+impl<'a, 'b> PartialEq<NakPduCreator<'a>> for NakPduReader<'b> {
+    fn eq(&self, other: &NakPduCreator<'a>) -> bool {
+        if self.pdu_header() != other.pdu_header()
+            || self.end_of_scope() != other.end_of_scope()
+            || self.start_of_scope() != other.start_of_scope()
+        {
+            return false;
+        }
+
+        // Check if both segment requests are empty or None
+        match (self.seg_reqs_raw.is_empty(), other.segment_requests()) {
+            (true, None) => true,
+            (true, Some(seg_reqs)) => seg_reqs.is_empty(),
+            (false, None) => false,
+            _ => {
+                // Compare based on file_flag
+                if self.file_flag() == LargeFileFlag::Normal {
+                    let normal_iter = self.get_normal_segment_requests_iterator().unwrap();
+                    normal_iter == *other.segment_requests().unwrap()
+                } else {
+                    let large_iter = self.get_large_segment_requests_iterator().unwrap();
+                    large_iter == *other.segment_requests().unwrap()
+                }
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use alloc::string::ToString;
+
+    use crate::cfdp::{
+        pdu::tests::{common_pdu_conf, verify_raw_header, TEST_DEST_ID, TEST_SEQ_NUM, TEST_SRC_ID},
+        PduType, TransmissionMode,
+    };
+
+    use super::*;
+
+    fn check_generic_fields(nak_pdu: &impl CfdpPdu) {
+        assert_eq!(nak_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(nak_pdu.file_flag(), LargeFileFlag::Normal);
+        assert_eq!(nak_pdu.pdu_type(), PduType::FileDirective);
+        assert_eq!(
+            nak_pdu.file_directive_type(),
+            Some(FileDirectiveType::NakPdu),
+        );
+        assert_eq!(nak_pdu.transmission_mode(), TransmissionMode::Acknowledged);
+        assert_eq!(nak_pdu.direction(), Direction::TowardsSender);
+        assert_eq!(nak_pdu.source_id(), TEST_SRC_ID.into());
+        assert_eq!(nak_pdu.dest_id(), TEST_DEST_ID.into());
+        assert_eq!(nak_pdu.transaction_seq_num(), TEST_SEQ_NUM.into());
+    }
+
+    #[test]
+    fn test_seg_request_api() {
+        let seg_req = SegmentRequests::U32Pairs(&[]);
+        assert!(seg_req.is_empty());
+        let seg_req = SegmentRequests::U64Pairs(&[]);
+        assert!(seg_req.is_empty());
+    }
+
+    #[test]
+    fn test_basic_creator() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new_no_segment_requests(pdu_header, 0, 0)
+            .expect("creating NAK PDU creator failed");
+        assert_eq!(nak_pdu.start_of_scope(), 0);
+        assert_eq!(nak_pdu.end_of_scope(), 0);
+        assert_eq!(nak_pdu.segment_requests(), None);
+        assert_eq!(nak_pdu.num_segment_reqs(), 0);
+        check_generic_fields(&nak_pdu);
+    }
+
+    #[test]
+    fn test_serialization_empty() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new_no_segment_requests(pdu_header, 100, 300)
+            .expect("creating NAK PDU creator failed");
+        assert_eq!(nak_pdu.start_of_scope(), 100);
+        assert_eq!(nak_pdu.end_of_scope(), 300);
+        let mut buf: [u8; 64] = [0; 64];
+        nak_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing NAK PDU to buffer failed");
+        verify_raw_header(nak_pdu.pdu_header(), &buf);
+        let mut current_idx = nak_pdu.pdu_header().header_len();
+        assert_eq!(current_idx + 9, nak_pdu.len_written());
+        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        current_idx += 1;
+        let start_of_scope =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(start_of_scope, 100);
+        current_idx += 4;
+        let end_of_scope =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(end_of_scope, 300);
+        current_idx += 4;
+        assert_eq!(current_idx, nak_pdu.len_written());
+    }
+
+    #[test]
+    fn test_serialization_two_segments() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new(pdu_header, 100, 300, &[(0, 0), (32, 64)])
+            .expect("creating NAK PDU creator failed");
+        let mut buf: [u8; 64] = [0; 64];
+        nak_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing NAK PDU to buffer failed");
+        verify_raw_header(nak_pdu.pdu_header(), &buf);
+        let mut current_idx = nak_pdu.pdu_header().header_len();
+        assert_eq!(current_idx + 9 + 16, nak_pdu.len_written());
+        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        current_idx += 1;
+        let start_of_scope =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(start_of_scope, 100);
+        current_idx += 4;
+        let end_of_scope =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(end_of_scope, 300);
+        current_idx += 4;
+        let first_seg_start =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(first_seg_start, 0);
+        current_idx += 4;
+        let first_seg_end =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(first_seg_end, 0);
+        current_idx += 4;
+        let second_seg_start =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(second_seg_start, 32);
+        current_idx += 4;
+        let second_seg_end =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        assert_eq!(second_seg_end, 64);
+        current_idx += 4;
+        assert_eq!(current_idx, nak_pdu.len_written());
+    }
+
+    #[test]
+    fn test_deserialization_empty() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new_no_segment_requests(pdu_header, 100, 300)
+            .expect("creating NAK PDU creator failed");
+        let mut buf: [u8; 64] = [0; 64];
+        nak_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing NAK PDU to buffer failed");
+        let nak_pdu_deser = NakPduReader::from_bytes(&buf).expect("deserializing NAK PDU failed");
+        assert_eq!(nak_pdu_deser, nak_pdu);
+        check_generic_fields(&nak_pdu_deser);
+    }
+
+    #[test]
+    fn test_deserialization_large_segments() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Large);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu =
+            NakPduCreator::new_large_file_size(pdu_header, 100, 300, &[(50, 100), (200, 300)])
+                .expect("creating NAK PDU creator failed");
+        let mut buf: [u8; 128] = [0; 128];
+        nak_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing NAK PDU to buffer failed");
+        let nak_pdu_deser = NakPduReader::from_bytes(&buf).expect("deserializing NAK PDU failed");
+        assert_eq!(nak_pdu_deser, nak_pdu);
+        assert_eq!(nak_pdu_deser.start_of_scope(), 100);
+        assert_eq!(nak_pdu_deser.end_of_scope(), 300);
+        assert_eq!(nak_pdu_deser.num_segment_reqs(), 2);
+        assert!(nak_pdu_deser
+            .get_large_segment_requests_iterator()
+            .is_some());
+        assert!(nak_pdu_deser
+            .get_normal_segment_requests_iterator()
+            .is_none());
+        assert_eq!(
+            nak_pdu_deser
+                .get_large_segment_requests_iterator()
+                .unwrap()
+                .count(),
+            2
+        );
+        for (idx, large_segments) in nak_pdu_deser
+            .get_large_segment_requests_iterator()
+            .unwrap()
+            .enumerate()
+        {
+            if idx == 0 {
+                assert_eq!(large_segments.0, 50);
+                assert_eq!(large_segments.1, 100);
+            } else {
+                assert_eq!(large_segments.0, 200);
+                assert_eq!(large_segments.1, 300);
+            }
+        }
+    }
+
+    #[test]
+    fn test_deserialization_normal_segments() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new(pdu_header, 100, 300, &[(50, 100), (200, 300)])
+            .expect("creating NAK PDU creator failed");
+        let mut buf: [u8; 128] = [0; 128];
+        nak_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing NAK PDU to buffer failed");
+        let nak_pdu_deser = NakPduReader::from_bytes(&buf).expect("deserializing NAK PDU failed");
+        assert_eq!(nak_pdu_deser, nak_pdu);
+        assert_eq!(nak_pdu_deser.start_of_scope(), 100);
+        assert_eq!(nak_pdu_deser.end_of_scope(), 300);
+        assert_eq!(nak_pdu_deser.num_segment_reqs(), 2);
+        assert!(nak_pdu_deser
+            .get_normal_segment_requests_iterator()
+            .is_some());
+        assert!(nak_pdu_deser
+            .get_large_segment_requests_iterator()
+            .is_none());
+        assert_eq!(
+            nak_pdu_deser
+                .get_normal_segment_requests_iterator()
+                .unwrap()
+                .count(),
+            2
+        );
+        for (idx, large_segments) in nak_pdu_deser
+            .get_normal_segment_requests_iterator()
+            .unwrap()
+            .enumerate()
+        {
+            if idx == 0 {
+                assert_eq!(large_segments.0, 50);
+                assert_eq!(large_segments.1, 100);
+            } else {
+                assert_eq!(large_segments.0, 200);
+                assert_eq!(large_segments.1, 300);
+            }
+        }
+    }
+
+    #[test]
+    fn test_empty_is_empty() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu_0 =
+            NakPduCreator::new(pdu_header, 100, 300, &[]).expect("creating NAK PDU creator failed");
+        let nak_pdu_1 = NakPduCreator::new_no_segment_requests(pdu_header, 100, 300)
+            .expect("creating NAK PDU creator failed");
+        assert_eq!(nak_pdu_0, nak_pdu_1);
+        // Assert the segment request is mapped to None.
+        assert!(nak_pdu_0.segment_requests().is_none());
+    }
+
+    #[test]
+    fn test_new_generic_invalid_input() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let u32_list = SegmentRequests::U32Pairs(&[(0, 50), (50, 100)]);
+        //let error = NakPduCreator::new_generic(pdu_header, 100, 300, Some(u32_list));
+        let error = NakPduCreator::new_generic(
+            pdu_header,
+            u32::MAX as u64 + 1,
+            u32::MAX as u64 + 2,
+            Some(u32_list),
+        );
+        assert!(error.is_err());
+        let error = error.unwrap_err();
+        if let PduError::InvalidStartOrEndOfScopeValue = error {
+            assert_eq!(
+                error.to_string(),
+                "invalid start or end of scope for NAK PDU"
+            );
+        } else {
+            panic!("unexpected error {error}");
+        }
+    }
+
+    #[test]
+    fn test_target_buf_too_small() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new_no_segment_requests(pdu_header, 100, 300)
+            .expect("creating NAK PDU creator failed");
+        assert_eq!(nak_pdu.start_of_scope(), 100);
+        assert_eq!(nak_pdu.end_of_scope(), 300);
+        let mut buf: [u8; 5] = [0; 5];
+        let error = nak_pdu.write_to_bytes(&mut buf);
+        assert!(error.is_err());
+        let e = error.unwrap_err();
+        match e {
+            PduError::ByteConversion(conv_error) => match conv_error {
+                ByteConversionError::ToSliceTooSmall { found, expected } => {
+                    assert_eq!(expected, nak_pdu.len_written());
+                    assert_eq!(found, 5);
+                }
+                _ => panic!("unexpected error {conv_error}"),
+            },
+            _ => panic!("unexpected error {e}"),
+        }
+    }
+
+    #[test]
+    fn test_with_crc() {
+        let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let nak_pdu = NakPduCreator::new_no_segment_requests(pdu_header, 0, 0)
+            .expect("creating NAK PDU creator failed");
+        let mut nak_vec = nak_pdu.to_vec().expect("writing NAK to vector failed");
+        assert_eq!(nak_vec.len(), pdu_header.header_len() + 9 + 2);
+        assert_eq!(nak_vec.len(), nak_pdu.len_written());
+        let nak_pdu_deser = NakPduReader::new(&nak_vec).expect("reading NAK PDU failed");
+        assert_eq!(nak_pdu_deser, nak_pdu);
+        nak_vec[nak_pdu.len_written() - 1] -= 1;
+        let nak_pdu_deser = NakPduReader::new(&nak_vec);
+        assert!(nak_pdu_deser.is_err());
+        if let Err(PduError::ChecksumError(raw)) = nak_pdu_deser {
+            assert_eq!(
+                raw,
+                u16::from_be_bytes(nak_vec[nak_pdu.len_written() - 2..].try_into().unwrap())
+            );
+        }
+    }
+}

src/cfdp/tlv/msg_to_user.rs

@@ -0,0 +1,173 @@
+//! Abstractions for the Message to User CFDP TLV subtype.
+use super::{GenericTlv, Tlv, TlvLvError, TlvType, TlvTypeField, WritableTlv};
+use crate::ByteConversionError;
+use delegate::delegate;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct MsgToUserTlv<'data> {
+    pub tlv: Tlv<'data>,
+}
+
+impl<'data> MsgToUserTlv<'data> {
+    /// Create a new message to user TLV where the type field is set correctly.
+    pub fn new(value: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvError> {
+        Ok(Self {
+            tlv: Tlv::new(TlvType::MsgToUser, value)?,
+        })
+    }
+
+    delegate! {
+        to self.tlv {
+            pub fn value(&self) -> &[u8];
+            /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
+            /// [Self::value]
+            pub fn len_value(&self) -> usize;
+            /// Returns the full raw length, including the length byte.
+            pub fn len_full(&self) -> usize;
+            /// Checks whether the value field is empty.
+            pub fn is_empty(&self) -> bool;
+            /// If the TLV was generated from a raw bytestream using [Self::from_bytes], the raw start
+            /// of the TLV can be retrieved with this method.
+            pub fn raw_data(&self) -> Option<&[u8]>;
+        }
+    }
+
+    pub fn is_standard_tlv(&self) -> bool {
+        true
+    }
+
+    pub fn tlv_type(&self) -> Option<TlvType> {
+        Some(TlvType::MsgToUser)
+    }
+
+    /// Check whether this message is a reserved CFDP message like a Proxy Operation Message.
+    pub fn is_reserved_cfdp_msg(&self) -> bool {
+        if self.value().len() < 4 {
+            return false;
+        }
+        let value = self.value();
+        if value[0] == b'c' && value[1] == b'f' && value[2] == b'd' && value[3] == b'p' {
+            return true;
+        }
+        false
+    }
+
+    /// This is a thin wrapper around [Tlv::from_bytes] with the additional type check.
+    pub fn from_bytes(buf: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvError> {
+        let msg_to_user = Self {
+            tlv: Tlv::from_bytes(buf)?,
+        };
+        match msg_to_user.tlv.tlv_type_field() {
+            TlvTypeField::Standard(tlv_type) => {
+                if tlv_type != TlvType::MsgToUser {
+                    return Err(TlvLvError::InvalidTlvTypeField {
+                        found: tlv_type as u8,
+                        expected: Some(TlvType::MsgToUser as u8),
+                    });
+                }
+            }
+            TlvTypeField::Custom(raw) => {
+                return Err(TlvLvError::InvalidTlvTypeField {
+                    found: raw,
+                    expected: Some(TlvType::MsgToUser as u8),
+                });
+            }
+        }
+        Ok(msg_to_user)
+    }
+}
+
+impl WritableTlv for MsgToUserTlv<'_> {
+    fn len_written(&self) -> usize {
+        self.len_full()
+    }
+
+    delegate!(
+        to self.tlv {
+            fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+        }
+    );
+}
+
+impl GenericTlv for MsgToUserTlv<'_> {
+    fn tlv_type_field(&self) -> TlvTypeField {
+        self.tlv.tlv_type_field()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_basic() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value);
+        assert!(msg_to_user.is_ok());
+        let msg_to_user = msg_to_user.unwrap();
+        assert!(msg_to_user.is_standard_tlv());
+        assert_eq!(msg_to_user.tlv_type().unwrap(), TlvType::MsgToUser);
+        assert_eq!(
+            msg_to_user.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+        assert_eq!(msg_to_user.value(), custom_value);
+        assert_eq!(msg_to_user.value().len(), 4);
+        assert_eq!(msg_to_user.len_value(), 4);
+        assert_eq!(msg_to_user.len_full(), 6);
+        assert!(!msg_to_user.is_empty());
+        assert!(msg_to_user.raw_data().is_none());
+        assert!(!msg_to_user.is_reserved_cfdp_msg());
+    }
+
+    #[test]
+    fn test_reserved_msg_serialization() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let mut buf: [u8; 6] = [0; 6];
+        msg_to_user.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(
+            buf,
+            [
+                TlvType::MsgToUser as u8,
+                custom_value.len() as u8,
+                1,
+                2,
+                3,
+                4
+            ]
+        );
+    }
+
+    #[test]
+    fn test_reserved_msg_deserialization() {
+        let custom_value: [u8; 3] = [1, 2, 3];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let msg_to_user_vec = msg_to_user.to_vec();
+        let msg_to_user_from_bytes = MsgToUserTlv::from_bytes(&msg_to_user_vec).unwrap();
+        assert!(!msg_to_user.is_reserved_cfdp_msg());
+        assert_eq!(msg_to_user_from_bytes, msg_to_user);
+        assert_eq!(msg_to_user_from_bytes.value(), msg_to_user.value());
+        assert_eq!(msg_to_user_from_bytes.tlv_type(), msg_to_user.tlv_type());
+    }
+    #[test]
+    fn test_reserved_msg_deserialization_invalid_type() {
+        let trash: [u8; 5] = [TlvType::FlowLabel as u8, 3, 1, 2, 3];
+        let error = MsgToUserTlv::from_bytes(&trash).unwrap_err();
+        if let TlvLvError::InvalidTlvTypeField { found, expected } = error {
+            assert_eq!(found, TlvType::FlowLabel as u8);
+            assert_eq!(expected, Some(TlvType::MsgToUser as u8));
+        } else {
+            panic!("Wrong error type returned: {:?}", error);
+        }
+    }
+
+    #[test]
+    fn test_reserved_msg() {
+        let reserved_str = "cfdp";
+        let msg_to_user = MsgToUserTlv::new(reserved_str.as_bytes());
+        assert!(msg_to_user.is_ok());
+        let msg_to_user = msg_to_user.unwrap();
+        assert!(msg_to_user.is_reserved_cfdp_msg());
+    }
+}

src/ecss/hk.rs

@@ -5,6 +5,7 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum Subservice {
     // Regular HK
@@ -29,3 +30,33 @@ pub enum Subservice {
     TcGenerateOneShotDiag = 28,
     TcModifyDiagCollectionInterval = 32,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_try_from_u8() {
+        let hk_report_subservice_raw = 25;
+        let hk_report: Subservice = Subservice::try_from(hk_report_subservice_raw).unwrap();
+        assert_eq!(hk_report, Subservice::TmHkPacket);
+    }
+
+    #[test]
+    fn test_into_u8() {
+        let hk_report_raw: u8 = Subservice::TmHkPacket.into();
+        assert_eq!(hk_report_raw, 25);
+    }
+
+    #[test]
+    fn test_partial_eq() {
+        let hk_report_raw = Subservice::TmHkPacket;
+        assert_ne!(hk_report_raw, Subservice::TcGenerateOneShotHk);
+        assert_eq!(hk_report_raw, Subservice::TmHkPacket);
+    }
+    #[test]
+    fn test_copy_clone() {
+        let hk_report = Subservice::TmHkPacket;
+        let hk_report_copy = hk_report;
+        assert_eq!(hk_report, hk_report_copy);
+    }
+}

src/ecss/mod.rs

@@ -1,12 +1,13 @@
 //! Common definitions and helpers required to create PUS TMTC packets according to
 //! [ECSS-E-ST-70-41C](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/)
 //!
-//! You can find the PUS telecommand definitions in the [crate::tc] module and ithe PUS telemetry definitions
-//! inside the [crate::tm] module.
-use crate::{ByteConversionError, CcsdsPacket, SizeMissmatch};
+//! You can find the PUS telecommand types in the [tc] module and the the PUS telemetry
+//! types inside the [tm] module.
+use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
 use core::fmt::{Debug, Display, Formatter};
 use core::mem::size_of;
-use crc::{Crc, CRC_16_IBM_3740};
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -16,14 +17,12 @@ use std::error::Error;
 pub mod event;
 pub mod hk;
 pub mod scheduling;
+pub mod tc;
+pub mod tm;
 pub mod verification;
 
 pub type CrcType = u16;
 
-/// CRC algorithm used by the PUS standard.
-pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
-pub const CCSDS_HEADER_LEN: usize = size_of::<crate::zc::SpHeader>();
-
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[repr(u8)]
@@ -74,6 +73,8 @@ pub enum PusServiceId {
 /// All PUS versions. Only PUS C is supported by this library.
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[non_exhaustive]
 pub enum PusVersion {
     EsaPus = 0,
     PusA = 1,
@@ -95,8 +96,9 @@ impl TryFrom<u8> for PusVersion {
 }
 
 /// ECSS Packet Type Codes (PTC)s.
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
 pub enum PacketTypeCodes {
     Boolean = 1,
     Enumerated = 2,
@@ -115,9 +117,10 @@ pub enum PacketTypeCodes {
 pub type Ptc = PacketTypeCodes;
 
 /// ECSS Packet Field Codes (PFC)s for the unsigned [Ptc].
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub enum UnsignedPfc {
+#[repr(u8)]
+pub enum PfcUnsigned {
     OneByte = 4,
     TwelveBits = 8,
     TwoBytes = 12,
@@ -131,9 +134,10 @@ pub enum UnsignedPfc {
 }
 
 /// ECSS Packet Field Codes (PFC)s for the real (floating point) [Ptc].
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub enum RealPfc {
+#[repr(u8)]
+pub enum PfcReal {
     /// 4 octets simple precision format (IEEE)
     Float = 1,
     /// 8 octets simple precision format (IEEE)
@@ -146,14 +150,13 @@ pub enum RealPfc {
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PusError {
     VersionNotSupported(PusVersion),
-    IncorrectCrc(u16),
-    RawDataTooShort(usize),
-    NoRawData,
+    ChecksumFailure(u16),
     /// CRC16 needs to be calculated first
     CrcCalculationMissing,
-    ByteConversionError(ByteConversionError),
+    ByteConversion(ByteConversionError),
 }
 
 impl Display for PusError {
@@ -162,23 +165,14 @@ impl Display for PusError {
             PusError::VersionNotSupported(v) => {
                 write!(f, "PUS version {v:?} not supported")
             }
-            PusError::IncorrectCrc(crc) => {
-                write!(f, "crc16 {crc:#04x} is incorrect")
-            }
-            PusError::RawDataTooShort(size) => {
-                write!(
-                    f,
-                    "deserialization error, provided raw data with size {size} too short"
-                )
-            }
-            PusError::NoRawData => {
-                write!(f, "no raw data provided")
+            PusError::ChecksumFailure(crc) => {
+                write!(f, "checksum verification for crc16 {crc:#06x} failed")
             }
             PusError::CrcCalculationMissing => {
                 write!(f, "crc16 was not calculated")
             }
-            PusError::ByteConversionError(e) => {
-                write!(f, "low level byte conversion error: {e}")
+            PusError::ByteConversion(e) => {
+                write!(f, "pus error: {e}")
             }
         }
     }
@@ -187,7 +181,7 @@ impl Display for PusError {
 #[cfg(feature = "std")]
 impl Error for PusError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
-        if let PusError::ByteConversionError(e) = self {
+        if let PusError::ByteConversion(e) = self {
             return Some(e);
         }
         None
@@ -196,7 +190,7 @@ impl Error for PusError {
 
 impl From<ByteConversionError> for PusError {
     fn from(e: ByteConversionError) -> Self {
-        PusError::ByteConversionError(e)
+        PusError::ByteConversion(e)
     }
 }
 
@@ -208,14 +202,16 @@ pub trait PusPacket: CcsdsPacket {
     fn pus_version(&self) -> PusVersion;
     fn service(&self) -> u8;
     fn subservice(&self) -> u8;
-
-    fn user_data(&self) -> Option<&[u8]>;
+    fn user_data(&self) -> &[u8];
     fn crc16(&self) -> Option<u16>;
 }
 
-pub(crate) fn crc_from_raw_data(raw_data: &[u8]) -> Result<u16, PusError> {
+pub(crate) fn crc_from_raw_data(raw_data: &[u8]) -> Result<u16, ByteConversionError> {
     if raw_data.len() < 2 {
-        return Err(PusError::RawDataTooShort(raw_data.len()));
+        return Err(ByteConversionError::FromSliceTooSmall {
+            found: raw_data.len(),
+            expected: 2,
+        });
     }
     Ok(u16::from_be_bytes(
         raw_data[raw_data.len() - 2..raw_data.len()]
@@ -230,52 +226,48 @@ pub(crate) fn calc_pus_crc16(bytes: &[u8]) -> u16 {
     digest.finalize()
 }
 
-pub(crate) fn crc_procedure(
-    calc_on_serialization: bool,
-    cached_crc16: &Option<u16>,
-    start_idx: usize,
-    curr_idx: usize,
-    slice: &[u8],
-) -> Result<u16, PusError> {
-    let crc16;
-    if calc_on_serialization {
-        crc16 = calc_pus_crc16(&slice[start_idx..curr_idx])
-    } else if cached_crc16.is_none() {
-        return Err(PusError::CrcCalculationMissing);
-    } else {
-        crc16 = cached_crc16.unwrap();
-    }
-    Ok(crc16)
-}
-
 pub(crate) fn user_data_from_raw(
     current_idx: usize,
     total_len: usize,
-    raw_data_len: usize,
     slice: &[u8],
-) -> Result<Option<&[u8]>, PusError> {
+) -> Result<&[u8], ByteConversionError> {
     match current_idx {
-        _ if current_idx == total_len - 2 => Ok(None),
-        _ if current_idx > total_len - 2 => Err(PusError::RawDataTooShort(raw_data_len)),
-        _ => Ok(Some(&slice[current_idx..total_len - 2])),
+        _ if current_idx > total_len - 2 => Err(ByteConversionError::FromSliceTooSmall {
+            found: total_len - 2,
+            expected: current_idx,
+        }),
+        _ => Ok(&slice[current_idx..total_len - 2]),
     }
 }
 
-pub(crate) fn verify_crc16_from_raw(raw_data: &[u8], crc16: u16) -> Result<(), PusError> {
+pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
+    raw_data: &[u8],
+    crc16: u16,
+) -> Result<(), PusError> {
+    verify_crc16_ccitt_false_from_raw(raw_data)
+        .then_some(())
+        .ok_or(PusError::ChecksumFailure(crc16))
+}
+
+pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
     let mut digest = CRC_CCITT_FALSE.digest();
     digest.update(raw_data);
     if digest.finalize() == 0 {
-        return Ok(());
+        return true;
     }
-    Err(PusError::IncorrectCrc(crc16))
+    false
 }
 
 macro_rules! ccsds_impl {
     () => {
         delegate!(to self.sp_header {
+            #[inline]
             fn ccsds_version(&self) -> u8;
+            #[inline]
             fn packet_id(&self) -> crate::PacketId;
+            #[inline]
             fn psc(&self) -> crate::PacketSequenceCtrl;
+            #[inline]
             fn data_len(&self) -> u16;
         });
     }
@@ -284,13 +276,17 @@ macro_rules! ccsds_impl {
 macro_rules! sp_header_impls {
     () => {
         delegate!(to self.sp_header {
+            #[inline]
             pub fn set_apid(&mut self, apid: u16) -> bool;
+            #[inline]
             pub fn set_seq_count(&mut self, seq_count: u16) -> bool;
+            #[inline]
             pub fn set_seq_flags(&mut self, seq_flag: SequenceFlags);
         });
     }
 }
 
+use crate::util::{GenericUnsignedByteField, ToBeBytes, UnsignedEnum};
 pub(crate) use ccsds_impl;
 pub(crate) use sp_header_impls;
 
@@ -298,118 +294,134 @@ pub(crate) use sp_header_impls;
 /// and an unsigned value. The trait makes no assumptions about the actual type of the unsigned
 /// value and only requires implementors to implement a function which writes the enumeration into
 /// a raw byte format.
-pub trait EcssEnumeration {
+pub trait EcssEnumeration: UnsignedEnum {
     /// Packet Format Code, which denotes the number of bits of the enumeration
     fn pfc(&self) -> u8;
-    fn byte_width(&self) -> usize {
-        (self.pfc() / 8) as usize
-    }
-    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError>;
 }
 
 pub trait EcssEnumerationExt: EcssEnumeration + Debug + Copy + Clone + PartialEq + Eq {}
 
-pub trait ToBeBytes {
-    type ByteArray: AsRef<[u8]>;
-    fn to_be_bytes(&self) -> Self::ByteArray;
-}
-
-impl ToBeBytes for () {
-    type ByteArray = [u8; 0];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        []
-    }
-}
-
-impl ToBeBytes for u8 {
-    type ByteArray = [u8; 1];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u8::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u16 {
-    type ByteArray = [u8; 2];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u16::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u32 {
-    type ByteArray = [u8; 4];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u32::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u64 {
-    type ByteArray = [u8; 8];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u64::to_be_bytes(*self)
-    }
-}
-
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct GenericEcssEnumWrapper<TYPE> {
-    val: TYPE,
+pub struct GenericEcssEnumWrapper<TYPE: Copy + Into<u64>> {
+    field: GenericUnsignedByteField<TYPE>,
 }
 
-impl<TYPE> GenericEcssEnumWrapper<TYPE> {
+impl<TYPE: Copy + Into<u64>> GenericEcssEnumWrapper<TYPE> {
     pub const fn ptc() -> PacketTypeCodes {
         PacketTypeCodes::Enumerated
     }
 
+    pub const fn value_typed(&self) -> TYPE {
+        self.field.value_typed()
+    }
+
     pub fn new(val: TYPE) -> Self {
-        Self { val }
+        Self {
+            field: GenericUnsignedByteField::new(val),
+        }
     }
 }
 
-impl<TYPE: ToBeBytes> EcssEnumeration for GenericEcssEnumWrapper<TYPE> {
+impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericEcssEnumWrapper<TYPE> {
+    fn size(&self) -> usize {
+        (self.pfc() / 8) as usize
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.field.write_to_be_bytes(buf)
+    }
+
+    fn value(&self) -> u64 {
+        self.field.value()
+    }
+}
+
+impl<TYPE: Copy + ToBeBytes + Into<u64>> EcssEnumeration for GenericEcssEnumWrapper<TYPE> {
     fn pfc(&self) -> u8 {
         size_of::<TYPE>() as u8 * 8_u8
     }
-
-    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError> {
-        if buf.len() < self.byte_width() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: buf.len(),
-                expected: self.byte_width(),
-            }));
-        }
-        buf[0..self.byte_width()].copy_from_slice(self.val.to_be_bytes().as_ref());
-        Ok(())
-    }
 }
 
-impl<TYPE: Debug + Copy + Clone + PartialEq + Eq + ToBeBytes> EcssEnumerationExt
+impl<TYPE: Debug + Copy + Clone + PartialEq + Eq + ToBeBytes + Into<u64>> EcssEnumerationExt
     for GenericEcssEnumWrapper<TYPE>
 {
 }
 
-pub type EcssEnumU8 = GenericEcssEnumWrapper<u8>;
-pub type EcssEnumU16 = GenericEcssEnumWrapper<u16>;
-pub type EcssEnumU32 = GenericEcssEnumWrapper<u32>;
-pub type EcssEnumU64 = GenericEcssEnumWrapper<u64>;
+impl<T: Copy + Into<u64>> From<T> for GenericEcssEnumWrapper<T> {
+    fn from(value: T) -> Self {
+        Self::new(value)
+    }
+}
+
+macro_rules! generic_ecss_enum_typedefs_and_from_impls {
+    ($($ty:ty => $Enum:ident),*) => {
+        $(
+            pub type $Enum = GenericEcssEnumWrapper<$ty>;
+
+            impl From<$Enum> for $ty {
+                fn from(value: $Enum) -> Self {
+                    value.value_typed()
+                }
+            }
+        )*
+    };
+}
+
+// Generates EcssEnum<$TY> type definitions as well as a From<$TY> for EcssEnum<$TY>
+// implementation.
+generic_ecss_enum_typedefs_and_from_impls! {
+    u8 => EcssEnumU8,
+    u16 => EcssEnumU16,
+    u32 => EcssEnumU32,
+    u64 => EcssEnumU64
+}
+
+/// Generic trait for PUS packet abstractions which can written to a raw slice as their raw
+/// byte representation. This is especially useful for generic abstractions which depend only
+/// on the serialization of those packets.
+pub trait WritablePusPacket {
+    fn len_written(&self) -> usize;
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+    #[cfg(feature = "alloc")]
+    fn to_vec(&self) -> Result<Vec<u8>, PusError> {
+        // This is the correct way to do this. See
+        // [this issue](https://github.com/rust-lang/rust-clippy/issues/4483) for caveats of more
+        // "efficient" implementations.
+        let mut vec = alloc::vec![0; self.len_written()];
+        self.write_to_bytes(&mut vec)?;
+        Ok(vec)
+    }
+}
 
 #[cfg(test)]
 mod tests {
-    use crate::ecss::{EcssEnumU16, EcssEnumU32, EcssEnumU8, EcssEnumeration};
+    use alloc::string::ToString;
+
+    use crate::ecss::{EcssEnumU16, EcssEnumU32, EcssEnumU8, UnsignedEnum};
     use crate::ByteConversionError;
 
+    use super::*;
+    #[cfg(feature = "serde")]
+    use crate::tests::generic_serde_test;
+
     #[test]
     fn test_enum_u8() {
         let mut buf = [0, 0, 0];
         let my_enum = EcssEnumU8::new(1);
+        assert_eq!(EcssEnumU8::ptc(), Ptc::Enumerated);
+        assert_eq!(my_enum.size(), 1);
+        assert_eq!(my_enum.pfc(), 8);
         my_enum
             .write_to_be_bytes(&mut buf[1..2])
             .expect("To byte conversion of u8 failed");
         assert_eq!(buf[1], 1);
+        assert_eq!(my_enum.value(), 1);
+        assert_eq!(my_enum.value_typed(), 1);
+        let enum_as_u8: u8 = my_enum.into();
+        assert_eq!(enum_as_u8, 1);
+        let vec = my_enum.to_vec();
+        assert_eq!(vec, buf[1..2]);
     }
 
     #[test]
@@ -419,8 +431,16 @@ mod tests {
         my_enum
             .write_to_be_bytes(&mut buf[1..3])
             .expect("To byte conversion of u8 failed");
+        assert_eq!(my_enum.size(), 2);
+        assert_eq!(my_enum.pfc(), 16);
         assert_eq!(buf[1], 0x1f);
         assert_eq!(buf[2], 0x2f);
+        assert_eq!(my_enum.value(), 0x1f2f);
+        assert_eq!(my_enum.value_typed(), 0x1f2f);
+        let enum_as_raw: u16 = my_enum.into();
+        assert_eq!(enum_as_raw, 0x1f2f);
+        let vec = my_enum.to_vec();
+        assert_eq!(vec, buf[1..3]);
     }
 
     #[test]
@@ -431,9 +451,9 @@ mod tests {
         assert!(res.is_err());
         let error = res.unwrap_err();
         match error {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.expected, 2);
-                assert_eq!(missmatch.found, 1);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(expected, 2);
+                assert_eq!(found, 1);
             }
             _ => {
                 panic!("Unexpected error {:?}", error);
@@ -452,6 +472,12 @@ mod tests {
         assert_eq!(buf[2], 0x2f);
         assert_eq!(buf[3], 0x3f);
         assert_eq!(buf[4], 0x4f);
+        assert_eq!(my_enum.value(), 0x1f2f3f4f);
+        assert_eq!(my_enum.value_typed(), 0x1f2f3f4f);
+        let enum_as_raw: u32 = my_enum.into();
+        assert_eq!(enum_as_raw, 0x1f2f3f4f);
+        let vec = my_enum.to_vec();
+        assert_eq!(vec, buf[1..5]);
     }
 
     #[test]
@@ -462,13 +488,108 @@ mod tests {
         assert!(res.is_err());
         let error = res.unwrap_err();
         match error {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.expected, 4);
-                assert_eq!(missmatch.found, 3);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(expected, 4);
+                assert_eq!(found, 3);
             }
             _ => {
                 panic!("Unexpected error {:?}", error);
             }
         }
     }
+
+    #[test]
+    fn test_enum_u64() {
+        let mut buf = [0; 8];
+        let my_enum = EcssEnumU64::new(0x1f2f3f4f5f);
+        my_enum
+            .write_to_be_bytes(&mut buf)
+            .expect("To byte conversion of u64 failed");
+        assert_eq!(buf[3], 0x1f);
+        assert_eq!(buf[4], 0x2f);
+        assert_eq!(buf[5], 0x3f);
+        assert_eq!(buf[6], 0x4f);
+        assert_eq!(buf[7], 0x5f);
+        assert_eq!(my_enum.value(), 0x1f2f3f4f5f);
+        assert_eq!(my_enum.value_typed(), 0x1f2f3f4f5f);
+        let enum_as_raw: u64 = my_enum.into();
+        assert_eq!(enum_as_raw, 0x1f2f3f4f5f);
+        assert_eq!(u64::from_be_bytes(buf), 0x1f2f3f4f5f);
+        let vec = my_enum.to_vec();
+        assert_eq!(vec, buf);
+    }
+
+    #[test]
+    fn test_pus_error_display() {
+        let unsupport_version = PusError::VersionNotSupported(super::PusVersion::EsaPus);
+        let write_str = unsupport_version.to_string();
+        assert_eq!(write_str, "PUS version EsaPus not supported")
+    }
+
+    #[test]
+    fn test_service_id_from_u8() {
+        let verification_id_raw = 1;
+        let verification_id = PusServiceId::try_from(verification_id_raw).unwrap();
+        assert_eq!(verification_id, PusServiceId::Verification);
+    }
+
+    #[test]
+    fn test_ptc_from_u8() {
+        let ptc_raw = Ptc::AbsoluteTime as u8;
+        let ptc = Ptc::try_from(ptc_raw).unwrap();
+        assert_eq!(ptc, Ptc::AbsoluteTime);
+    }
+
+    #[test]
+    fn test_unsigned_pfc_from_u8() {
+        let pfc_raw = PfcUnsigned::OneByte as u8;
+        let pfc = PfcUnsigned::try_from(pfc_raw).unwrap();
+        assert_eq!(pfc, PfcUnsigned::OneByte);
+    }
+
+    #[test]
+    fn test_real_pfc_from_u8() {
+        let pfc_raw = PfcReal::Double as u8;
+        let pfc = PfcReal::try_from(pfc_raw).unwrap();
+        assert_eq!(pfc, PfcReal::Double);
+    }
+
+    #[test]
+    fn test_pus_error_eq_impl() {
+        assert_eq!(
+            PusError::VersionNotSupported(PusVersion::EsaPus),
+            PusError::VersionNotSupported(PusVersion::EsaPus)
+        );
+    }
+
+    #[test]
+    fn test_pus_error_clonable() {
+        let pus_error = PusError::ChecksumFailure(0x0101);
+        let cloned = pus_error;
+        assert_eq!(pus_error, cloned);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_pus_service_id() {
+        generic_serde_test(PusServiceId::Verification);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_ptc() {
+        generic_serde_test(Ptc::AbsoluteTime);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_pfc_unsigned() {
+        generic_serde_test(PfcUnsigned::EightBytes);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_pfc_real() {
+        generic_serde_test(PfcReal::Double);
+    }
 }

src/ecss/scheduling.rs

@@ -54,6 +54,7 @@ pub enum SchedStatus {
 }
 
 impl From<bool> for SchedStatus {
+    #[inline]
     fn from(value: bool) -> Self {
         if value {
             SchedStatus::Enabled
@@ -76,6 +77,8 @@ pub enum TimeWindowType {
 #[cfg(test)]
 mod tests {
     use super::*;
+    #[cfg(feature = "serde")]
+    use crate::tests::generic_serde_test;
 
     #[test]
     fn test_bool_conv_0() {
@@ -102,4 +105,22 @@ mod tests {
         let subservice: Subservice = 22u8.try_into().unwrap();
         assert_eq!(subservice, Subservice::TcCreateScheduleGroup);
     }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_subservice_id() {
+        generic_serde_test(Subservice::TcEnableScheduling);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_sched_status() {
+        generic_serde_test(SchedStatus::Enabled);
+    }
+
+    #[test]
+    #[cfg(feature = "serde")]
+    fn test_serde_time_window_type() {
+        generic_serde_test(TimeWindowType::SelectAll);
+    }
 }

src/lib.rs

@@ -7,6 +7,8 @@
 //!
 //!  - Space Packet implementation according to
 //!    [CCSDS Blue Book 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf)
+//!  - CCSDS File Delivery Protocol (CFDP) packet implementations according to
+//!    [CCSDS Blue Book 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf)
 //!  - PUS Telecommand and PUS Telemetry implementation according to the
 //!    [ECSS-E-ST-70-41C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
 //!  - CUC (CCSDS Unsegmented Time Code) implementation according to
@@ -20,10 +22,6 @@
 //!
 //! `spacepackets` supports various runtime environments and is also suitable for `no_std` environments.
 //!
-//! It also offers optional support for [`serde`](https://serde.rs/). This allows serializing and
-//! deserializing them with an appropriate `serde` provider like
-//! [`postcard`](https://github.com/jamesmunns/postcard).
-//!
 //! ### Default features
 //!
 //!  - [`std`](https://doc.rust-lang.org/std/): Enables functionality relying on the standard library.
@@ -34,7 +32,11 @@
 //! ### Optional features
 //!
 //!  - [`serde`](https://serde.rs/): Adds `serde` support for most types by adding `Serialize` and
-//!    `Deserialize` `derive`s
+//!    `Deserialize` `derives.
+//!  - [`chrono`](https://crates.io/crates/chrono): Add basic support for the `chrono` time library.
+//!  - [`timelib`](https://crates.io/crates/time): Add basic support for the `time` time library.
+//!  - [`defmt`](https://defmt.ferrous-systems.com/): Add support for the `defmt` by adding the
+//!    [`defmt::Format`](https://defmt.ferrous-systems.com/format) derive on many types.
 //!
 //! ## Module
 //!
@@ -46,54 +48,64 @@
 //!
 //! ```rust
 //! use spacepackets::SpHeader;
-//! let sp_header = SpHeader::tc_unseg(0x42, 12, 1).expect("Error creating CCSDS TC header");
+//! let sp_header = SpHeader::new_for_unseg_tc_checked(0x42, 12, 1).expect("error creating CCSDS TC header");
 //! println!("{:?}", sp_header);
 //! let mut ccsds_buf: [u8; 32] = [0; 32];
 //! sp_header.write_to_be_bytes(&mut ccsds_buf).expect("Writing CCSDS TC header failed");
 //! println!("{:x?}", &ccsds_buf[0..6]);
 //! ```
 #![no_std]
-#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#![cfg_attr(docs_rs, feature(doc_auto_cfg))]
 #[cfg(feature = "alloc")]
 extern crate alloc;
 #[cfg(any(feature = "std", test))]
 extern crate std;
 
-use crate::ecss::CCSDS_HEADER_LEN;
-use core::fmt::{Display, Formatter};
+use core::{
+    fmt::{Debug, Display, Formatter},
+    hash::Hash,
+};
+use crc::{Crc, CRC_16_IBM_3740};
 use delegate::delegate;
+
 #[cfg(feature = "std")]
 use std::error::Error;
 
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+pub mod cfdp;
 pub mod ecss;
-pub mod tc;
 pub mod time;
-pub mod tm;
+pub mod util;
 
 mod private {
     pub trait Sealed {}
 }
 
+pub const CCSDS_HEADER_LEN: usize = core::mem::size_of::<crate::zc::SpHeader>();
+
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard.
+pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
+
 pub const MAX_APID: u16 = 2u16.pow(11) - 1;
 pub const MAX_SEQ_COUNT: u16 = 2u16.pow(14) - 1;
 
+/// Generic error type when converting to and from raw byte slices.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct SizeMissmatch {
-    pub found: usize,
-    pub expected: usize,
-}
-
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum ByteConversionError {
     /// The passed slice is too small. Returns the passed slice length and expected minimum size
-    ToSliceTooSmall(SizeMissmatch),
+    ToSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
     /// The provider buffer is too small. Returns the passed slice length and expected minimum size
-    FromSliceTooSmall(SizeMissmatch),
+    FromSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
     /// The [zerocopy] library failed to write to bytes
     ZeroCopyToError,
     ZeroCopyFromError,
@@ -102,18 +114,18 @@ pub enum ByteConversionError {
 impl Display for ByteConversionError {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         match self {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
                 write!(
                     f,
                     "target slice with size {} is too small, expected size of at least {}",
-                    missmatch.found, missmatch.expected
+                    found, expected
                 )
             }
-            ByteConversionError::FromSliceTooSmall(missmatch) => {
+            ByteConversionError::FromSliceTooSmall { found, expected } => {
                 write!(
                     f,
                     "source slice with size {} too small, expected at least {} bytes",
-                    missmatch.found, missmatch.expected
+                    found, expected
                 )
             }
             ByteConversionError::ZeroCopyToError => {
@@ -132,6 +144,7 @@ impl Error for ByteConversionError {}
 /// CCSDS packet type enumeration.
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PacketType {
     Tm = 0,
     Tc = 1,
@@ -155,6 +168,7 @@ pub fn packet_type_in_raw_packet_id(packet_id: u16) -> PacketType {
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum SequenceFlags {
     ContinuationSegment = 0b00,
     FirstSegment = 0b01,
@@ -180,15 +194,45 @@ impl TryFrom<u8> for SequenceFlags {
 
 /// Abstraction for the CCSDS Packet ID, which forms the last thirteen bits
 /// of the first two bytes in the CCSDS primary header.
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PacketId {
     pub ptype: PacketType,
     pub sec_header_flag: bool,
     apid: u16,
 }
 
+impl PartialEq for PacketId {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        self.raw().eq(&other.raw())
+    }
+}
+
+impl PartialOrd for PacketId {
+    #[inline]
+    fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for PacketId {
+    #[inline]
+    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
+        self.raw().cmp(&other.raw())
+    }
+}
+
+impl Hash for PacketId {
+    fn hash<H: core::hash::Hasher>(&self, state: &mut H) {
+        let raw = self.raw();
+        raw.hash(state);
+    }
+}
+
 impl Default for PacketId {
+    #[inline]
     fn default() -> Self {
         PacketId {
             ptype: PacketType::Tm,
@@ -199,23 +243,34 @@ impl Default for PacketId {
 }
 
 impl PacketId {
-    pub const fn const_tc(sec_header: bool, apid: u16) -> Self {
-        Self::const_new(PacketType::Tc, sec_header, apid)
-    }
-
-    pub const fn const_tm(sec_header: bool, apid: u16) -> Self {
-        Self::const_new(PacketType::Tm, sec_header, apid)
-    }
-
-    pub fn tc(sec_header: bool, apid: u16) -> Option<Self> {
+    /// This constructor will panic if the passed APID exceeds [MAX_APID].
+    /// Use the checked constructor variants to avoid panics.
+    #[inline]
+    pub const fn new_for_tc(sec_header: bool, apid: u16) -> Self {
         Self::new(PacketType::Tc, sec_header, apid)
     }
 
-    pub fn tm(sec_header: bool, apid: u16) -> Option<Self> {
+    /// This constructor will panic if the passed APID exceeds [MAX_APID].
+    /// Use the checked constructor variants to avoid panics.
+    #[inline]
+    pub const fn new_for_tm(sec_header: bool, apid: u16) -> Self {
         Self::new(PacketType::Tm, sec_header, apid)
     }
 
-    pub const fn const_new(ptype: PacketType, sec_header: bool, apid: u16) -> Self {
+    #[inline]
+    pub fn new_for_tc_checked(sec_header: bool, apid: u16) -> Option<Self> {
+        Self::new_checked(PacketType::Tc, sec_header, apid)
+    }
+
+    #[inline]
+    pub fn new_for_tm_checked(sec_header: bool, apid: u16) -> Option<Self> {
+        Self::new_checked(PacketType::Tm, sec_header, apid)
+    }
+
+    /// This constructor will panic if the passed APID exceeds [MAX_APID].
+    /// Use the checked variants to avoid panics.
+    #[inline]
+    pub const fn new(ptype: PacketType, sec_header: bool, apid: u16) -> Self {
         if apid > MAX_APID {
             panic!("APID too large");
         }
@@ -226,16 +281,18 @@ impl PacketId {
         }
     }
 
-    pub fn new(ptype: PacketType, sec_header_flag: bool, apid: u16) -> Option<PacketId> {
+    #[inline]
+    pub fn new_checked(ptype: PacketType, sec_header_flag: bool, apid: u16) -> Option<PacketId> {
         if apid > MAX_APID {
             return None;
         }
-        Some(PacketId::const_new(ptype, sec_header_flag, apid))
+        Some(PacketId::new(ptype, sec_header_flag, apid))
     }
 
     /// Set a new Application Process ID (APID). If the passed number is invalid, the APID will
     /// not be set and false will be returned. The maximum allowed value for the 11-bit field is
     /// 2047
+    #[inline]
     pub fn set_apid(&mut self, apid: u16) -> bool {
         if apid > MAX_APID {
             return false;
@@ -244,10 +301,12 @@ impl PacketId {
         true
     }
 
+    #[inline]
     pub fn apid(&self) -> u16 {
         self.apid
     }
 
+    #[inline]
     pub fn raw(&self) -> u16 {
         ((self.ptype as u16) << 12) | ((self.sec_header_flag as u16) << 11) | self.apid
     }
@@ -267,15 +326,17 @@ impl From<u16> for PacketId {
 /// third and the fourth byte in the CCSDS primary header.
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PacketSequenceCtrl {
     pub seq_flags: SequenceFlags,
     seq_count: u16,
 }
 
 impl PacketSequenceCtrl {
-    /// const variant of [PacketSequenceCtrl::new], but panics if the sequence count exceeds
-    /// [MAX_SEQ_COUNT].
-    const fn const_new(seq_flags: SequenceFlags, seq_count: u16) -> PacketSequenceCtrl {
+    /// This constructor panics if the sequence count exceeds [MAX_SEQ_COUNT].
+    /// Use [Self::new_checked] to avoid panics.
+    #[inline]
+    pub const fn new(seq_flags: SequenceFlags, seq_count: u16) -> PacketSequenceCtrl {
         if seq_count > MAX_SEQ_COUNT {
             panic!("Sequence count too large");
         }
@@ -286,18 +347,22 @@ impl PacketSequenceCtrl {
     }
 
     /// Returns [None] if the passed sequence count exceeds [MAX_SEQ_COUNT].
-    pub fn new(seq_flags: SequenceFlags, seq_count: u16) -> Option<PacketSequenceCtrl> {
+    #[inline]
+    pub fn new_checked(seq_flags: SequenceFlags, seq_count: u16) -> Option<PacketSequenceCtrl> {
         if seq_count > MAX_SEQ_COUNT {
             return None;
         }
-        Some(PacketSequenceCtrl::const_new(seq_flags, seq_count))
+        Some(PacketSequenceCtrl::new(seq_flags, seq_count))
     }
+
+    #[inline]
     pub fn raw(&self) -> u16 {
         ((self.seq_flags as u16) << 14) | self.seq_count
     }
 
     /// Set a new sequence count. If the passed number is invalid, the sequence count will not be
     /// set and false will be returned. The maximum allowed value for the 14-bit field is 16383.
+    #[inline]
     pub fn set_seq_count(&mut self, ssc: u16) -> bool {
         if ssc > MAX_SEQ_COUNT {
             return false;
@@ -306,6 +371,7 @@ impl PacketSequenceCtrl {
         true
     }
 
+    #[inline]
     pub fn seq_count(&self) -> u16 {
         self.seq_count
     }
@@ -347,6 +413,7 @@ pub trait CcsdsPacket {
     /// Retrieve data length field
     fn data_len(&self) -> u16;
     /// Retrieve the total packet size based on the data length field
+    #[inline]
     fn total_len(&self) -> usize {
         usize::from(self.data_len()) + CCSDS_HEADER_LEN + 1
     }
@@ -427,6 +494,7 @@ pub trait CcsdsPrimaryHeader {
 /// * `data_len` - Data length field occupies the fifth and the sixth byte of the raw header
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct SpHeader {
     pub version: u8,
     pub packet_id: PacketId,
@@ -434,9 +502,12 @@ pub struct SpHeader {
     pub data_len: u16,
 }
 
+pub type SpacePacketHeader = SpHeader;
+
 impl Default for SpHeader {
-    /// The default function sets the sequence flag field to [SequenceFlags::Unsegmented]. The data
-    /// length field is set to 1, which denotes an empty space packets.
+    /// The default function sets the sequence flag field to [SequenceFlags::Unsegmented] and the
+    /// data length to 0.
+    #[inline]
     fn default() -> Self {
         SpHeader {
             version: 0,
@@ -445,12 +516,13 @@ impl Default for SpHeader {
                 seq_flags: SequenceFlags::Unsegmented,
                 seq_count: 0,
             },
-            data_len: 1,
+            data_len: 0,
         }
     }
 }
 
 impl SpHeader {
+    #[inline]
     pub const fn new(packet_id: PacketId, psc: PacketSequenceCtrl, data_len: u16) -> Self {
         Self {
             version: 0,
@@ -460,9 +532,43 @@ impl SpHeader {
         }
     }
 
-    /// const variant of the [SpHeader::new_fron_single_fields] function. Panics if the passed
-    /// APID exceeds [MAX_APID] or the passed packet sequence count exceeds [MAX_SEQ_COUNT].
-    const fn const_new_from_single_fields(
+    /// This constructor sets the sequence flag field to [SequenceFlags::Unsegmented] and the data
+    /// length to 0.
+    ///
+    /// This constructor will panic if the APID exceeds [MAX_APID].
+    #[inline]
+    pub const fn new_from_apid(apid: u16) -> Self {
+        SpHeader {
+            version: 0,
+            packet_id: PacketId::new(PacketType::Tm, false, apid),
+            psc: PacketSequenceCtrl {
+                seq_flags: SequenceFlags::Unsegmented,
+                seq_count: 0,
+            },
+            data_len: 0,
+        }
+    }
+
+    /// Checked variant of [Self::new_from_apid].
+    #[inline]
+    pub fn new_from_apid_checked(apid: u16) -> Option<Self> {
+        Some(SpHeader {
+            version: 0,
+            packet_id: PacketId::new_checked(PacketType::Tm, false, apid)?,
+            psc: PacketSequenceCtrl {
+                seq_flags: SequenceFlags::Unsegmented,
+                seq_count: 0,
+            },
+            data_len: 0,
+        })
+    }
+
+    /// This constructor panics if the passed APID exceeds [MAX_APID] or the passed packet sequence
+    /// count exceeds [MAX_SEQ_COUNT].
+    ///
+    /// The checked constructor variants can be used to avoid panics.
+    #[inline]
+    pub const fn new_from_fields(
         ptype: PacketType,
         sec_header: bool,
         apid: u16,
@@ -477,17 +583,20 @@ impl SpHeader {
             panic!("APID is too large");
         }
         Self {
-            psc: PacketSequenceCtrl::const_new(seq_flags, seq_count),
-            packet_id: PacketId::const_new(ptype, sec_header, apid),
+            psc: PacketSequenceCtrl::new(seq_flags, seq_count),
+            packet_id: PacketId::new(ptype, sec_header, apid),
             data_len,
             version: 0,
         }
     }
 
     /// Create a new Space Packet Header instance which can be used to create generic
-    /// Space Packets. This will return [None] if the APID or sequence count argument
+    /// Space Packets.
+    ///
+    /// This will return [None] if the APID or sequence count argument
     /// exceed [MAX_APID] or [MAX_SEQ_COUNT] respectively. The version field is set to 0b000.
-    pub fn new_from_single_fields(
+    #[inline]
+    pub fn new_from_fields_checked(
         ptype: PacketType,
         sec_header: bool,
         apid: u16,
@@ -498,56 +607,117 @@ impl SpHeader {
         if seq_count > MAX_SEQ_COUNT || apid > MAX_APID {
             return None;
         }
-        Some(SpHeader::const_new_from_single_fields(
+        Some(SpHeader::new_from_fields(
             ptype, sec_header, apid, seq_flags, seq_count, data_len,
         ))
     }
 
     /// Helper function for telemetry space packet headers. The packet type field will be
     /// set accordingly. The secondary header flag field is set to false.
-    pub fn tm(apid: u16, seq_flags: SequenceFlags, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::new_from_single_fields(PacketType::Tm, false, apid, seq_flags, seq_count, data_len)
+    #[inline]
+    pub fn new_for_tm_checked(
+        apid: u16,
+        seq_flags: SequenceFlags,
+        seq_count: u16,
+        data_len: u16,
+    ) -> Option<Self> {
+        Self::new_from_fields_checked(PacketType::Tm, false, apid, seq_flags, seq_count, data_len)
     }
 
     /// Helper function for telemetry space packet headers. The packet type field will be
     /// set accordingly. The secondary header flag field is set to false.
-    pub fn tc(apid: u16, seq_flags: SequenceFlags, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::new_from_single_fields(PacketType::Tc, false, apid, seq_flags, seq_count, data_len)
+    #[inline]
+    pub fn new_for_tc_checked(
+        apid: u16,
+        seq_flags: SequenceFlags,
+        seq_count: u16,
+        data_len: u16,
+    ) -> Option<Self> {
+        Self::new_from_fields_checked(PacketType::Tc, false, apid, seq_flags, seq_count, data_len)
     }
 
-    /// Variant of [SpHeader::tm] which sets the sequence flag field to [SequenceFlags::Unsegmented]
-    pub fn tm_unseg(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::tm(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    /// This is an unchecked constructor which can panic on invalid input.
+    #[inline]
+    pub const fn new_for_tm(
+        apid: u16,
+        seq_flags: SequenceFlags,
+        seq_count: u16,
+        data_len: u16,
+    ) -> Self {
+        Self::new_from_fields(PacketType::Tm, false, apid, seq_flags, seq_count, data_len)
     }
 
-    /// Variant of [SpHeader::tc] which sets the sequence flag field to [SequenceFlags::Unsegmented]
-    pub fn tc_unseg(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::tc(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    /// This is an unchecked constructor which can panic on invalid input.
+    #[inline]
+    pub const fn new_for_tc(
+        apid: u16,
+        seq_flags: SequenceFlags,
+        seq_count: u16,
+        data_len: u16,
+    ) -> Self {
+        Self::new_from_fields(PacketType::Tc, false, apid, seq_flags, seq_count, data_len)
     }
 
-    //noinspection RsTraitImplementation
-    delegate!(to self.packet_id {
-        /// Returns [false] and fails if the APID exceeds [MAX_APID]
-        pub fn set_apid(&mut self, apid: u16) -> bool;
-    });
+    /// Variant of [SpHeader::new_for_tm_checked] which sets the sequence flag field to [SequenceFlags::Unsegmented]
+    #[inline]
+    pub fn new_for_unseg_tm_checked(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::new_for_tm_checked(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    }
 
-    delegate!(to self.psc {
-        /// Returns [false] and fails if the sequence count exceeds [MAX_SEQ_COUNT]
-        pub fn set_seq_count(&mut self, seq_count: u16) -> bool;
-    });
+    /// Variant of [SpHeader::new_for_tc_checked] which sets the sequence flag field to [SequenceFlags::Unsegmented]
+    #[inline]
+    pub fn new_for_unseg_tc_checked(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::new_for_tc_checked(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    }
 
+    /// Variant of [SpHeader::new_for_tc] which sets the sequence flag field to [SequenceFlags::Unsegmented].
+    ///
+    /// This is an unchecked constructor which can panic on invalid input.
+    #[inline]
+    pub const fn new_for_unseg_tc(apid: u16, seq_count: u16, data_len: u16) -> Self {
+        Self::new_for_tc(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    }
+
+    /// Variant of [SpHeader::new_for_tm] which sets the sequence flag field to [SequenceFlags::Unsegmented].
+    ///
+    /// This is an unchecked constructor which can panic on invalid input.
+    #[inline]
+    pub const fn new_for_unseg_tm(apid: u16, seq_count: u16, data_len: u16) -> Self {
+        Self::new_for_tm(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    }
+
+    delegate! {
+        to self.packet_id {
+            /// Returns [false] and fails if the APID exceeds [MAX_APID]
+            #[inline]
+            pub fn set_apid(&mut self, apid: u16) -> bool;
+        }
+    }
+
+    delegate! {
+        to self.psc {
+            /// Returns [false] and fails if the sequence count exceeds [MAX_SEQ_COUNT]
+            #[inline]
+            pub fn set_seq_count(&mut self, seq_count: u16) -> bool;
+        }
+    }
+
+    #[inline]
     pub fn set_seq_flags(&mut self, seq_flags: SequenceFlags) {
         self.psc.seq_flags = seq_flags;
     }
 
+    #[inline]
     pub fn set_sec_header_flag(&mut self) {
         self.packet_id.sec_header_flag = true;
     }
 
+    #[inline]
     pub fn clear_sec_header_flag(&mut self) {
         self.packet_id.sec_header_flag = false;
     }
 
+    #[inline]
     pub fn set_packet_type(&mut self, packet_type: PacketType) {
         self.packet_id.ptype = packet_type;
     }
@@ -557,10 +727,10 @@ impl SpHeader {
     /// CCSDS header.
     pub fn from_be_bytes(buf: &[u8]) -> Result<(Self, &[u8]), ByteConversionError> {
         if buf.len() < CCSDS_HEADER_LEN {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: CCSDS_HEADER_LEN,
-            }));
+            });
         }
         let zc_header = zc::SpHeader::from_bytes(&buf[0..CCSDS_HEADER_LEN])
             .ok_or(ByteConversionError::ZeroCopyFromError)?;
@@ -574,10 +744,10 @@ impl SpHeader {
         buf: &'a mut [u8],
     ) -> Result<&'a mut [u8], ByteConversionError> {
         if buf.len() < CCSDS_HEADER_LEN {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: CCSDS_HEADER_LEN,
-            }));
+            });
         }
         let zc_header: zc::SpHeader = zc::SpHeader::from(*self);
         zc_header
@@ -585,6 +755,15 @@ impl SpHeader {
             .ok_or(ByteConversionError::ZeroCopyToError)?;
         Ok(&mut buf[CCSDS_HEADER_LEN..])
     }
+
+    /// Create a vector containing the CCSDS header.
+    #[cfg(feature = "alloc")]
+    pub fn to_vec(&self) -> alloc::vec::Vec<u8> {
+        let mut vec = alloc::vec![0; CCSDS_HEADER_LEN];
+        // This can not fail.
+        self.write_to_be_bytes(&mut vec[..]).unwrap();
+        vec
+    }
 }
 
 impl CcsdsPacket for SpHeader {
@@ -610,6 +789,7 @@ impl CcsdsPacket for SpHeader {
 }
 
 impl CcsdsPrimaryHeader for SpHeader {
+    #[inline]
     fn from_composite_fields(
         packet_id: PacketId,
         psc: PacketSequenceCtrl,
@@ -634,9 +814,9 @@ sph_from_other!(SpHeader, crate::zc::SpHeader);
 pub mod zc {
     use crate::{CcsdsPacket, CcsdsPrimaryHeader, PacketId, PacketSequenceCtrl, VERSION_MASK};
     use zerocopy::byteorder::NetworkEndian;
-    use zerocopy::{AsBytes, FromBytes, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, Unaligned, U16};
 
-    #[derive(FromBytes, AsBytes, Unaligned, Debug)]
+    #[derive(FromBytes, FromZeroes, AsBytes, Unaligned, Debug)]
     #[repr(C)]
     pub struct SpHeader {
         version_packet_id: U16<NetworkEndian>,
@@ -677,9 +857,12 @@ pub mod zc {
             ((self.version_packet_id.get() >> 13) as u8) & 0b111
         }
 
+        #[inline]
         fn packet_id(&self) -> PacketId {
             PacketId::from(self.packet_id_raw())
         }
+
+        #[inline]
         fn psc(&self) -> PacketSequenceCtrl {
             PacketSequenceCtrl::from(self.psc_raw())
         }
@@ -689,10 +872,12 @@ pub mod zc {
             self.data_len.get()
         }
 
+        #[inline]
         fn packet_id_raw(&self) -> u16 {
             self.version_packet_id.get() & (!VERSION_MASK)
         }
 
+        #[inline]
         fn psc_raw(&self) -> u16 {
             self.psc.get()
         }
@@ -713,7 +898,11 @@ pub mod zc {
 }
 
 #[cfg(all(test, feature = "std"))]
-mod tests {
+pub(crate) mod tests {
+    use std::collections::HashSet;
+
+    #[allow(unused_imports)]
+    use crate::ByteConversionError;
     #[cfg(feature = "serde")]
     use crate::CcsdsPrimaryHeader;
     use crate::{
@@ -721,24 +910,38 @@ mod tests {
     };
     use crate::{SequenceFlags, SpHeader};
     use alloc::vec;
+    #[cfg(feature = "serde")]
+    use core::fmt::Debug;
     use num_traits::pow;
     #[cfg(feature = "serde")]
     use postcard::{from_bytes, to_allocvec};
+    #[cfg(feature = "serde")]
+    use serde::{de::DeserializeOwned, Serialize};
 
     const CONST_SP: SpHeader = SpHeader::new(
-        PacketId::const_tc(true, 0x36),
-        PacketSequenceCtrl::const_new(SequenceFlags::ContinuationSegment, 0x88),
+        PacketId::new_for_tc(true, 0x36),
+        PacketSequenceCtrl::new(SequenceFlags::ContinuationSegment, 0x88),
         0x90,
     );
 
-    const PACKET_ID_TM: PacketId = PacketId::const_tm(true, 0x22);
+    const PACKET_ID_TM: PacketId = PacketId::new_for_tm(true, 0x22);
+
+    #[cfg(feature = "serde")]
+    pub(crate) fn generic_serde_test<T: Serialize + DeserializeOwned + PartialEq + Debug>(
+        value: T,
+    ) {
+        let output: alloc::vec::Vec<u8> = to_allocvec(&value).unwrap();
+        let output_converted_back: T = from_bytes(&output).unwrap();
+        assert_eq!(output_converted_back, value);
+    }
 
     #[test]
+    #[allow(clippy::assertions_on_constants)]
     fn verify_const_packet_id() {
         assert_eq!(PACKET_ID_TM.apid(), 0x22);
-        assert_eq!(PACKET_ID_TM.sec_header_flag, true);
+        assert!(PACKET_ID_TM.sec_header_flag);
         assert_eq!(PACKET_ID_TM.ptype, PacketType::Tm);
-        let const_tc_id = PacketId::const_tc(true, 0x23);
+        let const_tc_id = PacketId::new_for_tc(true, 0x23);
         assert_eq!(const_tc_id.ptype, PacketType::Tc);
     }
 
@@ -747,32 +950,32 @@ mod tests {
         let id_default = PacketId::default();
         assert_eq!(id_default.ptype, PacketType::Tm);
         assert_eq!(id_default.apid, 0x000);
-        assert_eq!(id_default.sec_header_flag, false);
+        assert!(!id_default.sec_header_flag);
     }
 
     #[test]
     fn test_packet_id_ctors() {
-        let packet_id = PacketId::new(PacketType::Tc, true, 0x1ff);
+        let packet_id = PacketId::new_checked(PacketType::Tc, true, 0x1ff);
         assert!(packet_id.is_some());
         let packet_id = packet_id.unwrap();
         assert_eq!(packet_id.apid(), 0x1ff);
         assert_eq!(packet_id.ptype, PacketType::Tc);
-        assert_eq!(packet_id.sec_header_flag, true);
-        let packet_id_tc = PacketId::tc(true, 0x1ff);
+        assert!(packet_id.sec_header_flag);
+        let packet_id_tc = PacketId::new_for_tc_checked(true, 0x1ff);
         assert!(packet_id_tc.is_some());
         let packet_id_tc = packet_id_tc.unwrap();
         assert_eq!(packet_id_tc, packet_id);
-        let packet_id_tm = PacketId::tm(true, 0x2ff);
+        let packet_id_tm = PacketId::new_for_tm_checked(true, 0x2ff);
         assert!(packet_id_tm.is_some());
         let packet_id_tm = packet_id_tm.unwrap();
-        assert_eq!(packet_id_tm.sec_header_flag, true);
+        assert!(packet_id_tm.sec_header_flag);
         assert_eq!(packet_id_tm.ptype, PacketType::Tm);
         assert_eq!(packet_id_tm.apid, 0x2ff);
     }
 
     #[test]
     fn verify_const_sp_header() {
-        assert_eq!(CONST_SP.sec_header_flag(), true);
+        assert!(CONST_SP.sec_header_flag());
         assert_eq!(CONST_SP.apid(), 0x36);
         assert_eq!(
             CONST_SP.sequence_flags(),
@@ -813,7 +1016,7 @@ mod tests {
     #[test]
     fn test_packet_id() {
         let packet_id =
-            PacketId::new(PacketType::Tm, false, 0x42).expect("Packet ID creation failed");
+            PacketId::new_checked(PacketType::Tm, false, 0x42).expect("Packet ID creation failed");
         assert_eq!(packet_id.raw(), 0x0042);
         let packet_id_from_raw = PacketId::from(packet_id.raw());
         assert_eq!(
@@ -821,33 +1024,34 @@ mod tests {
             PacketType::Tm
         );
         assert_eq!(packet_id_from_raw, packet_id);
-        let packet_id_from_new = PacketId::new(PacketType::Tm, false, 0x42).unwrap();
+        let packet_id_from_new = PacketId::new_checked(PacketType::Tm, false, 0x42).unwrap();
         assert_eq!(packet_id_from_new, packet_id);
     }
 
     #[test]
     fn test_invalid_packet_id() {
-        let packet_id_invalid = PacketId::new(PacketType::Tc, true, 0xFFFF);
+        let packet_id_invalid = PacketId::new_checked(PacketType::Tc, true, 0xFFFF);
         assert!(packet_id_invalid.is_none());
     }
 
     #[test]
     fn test_invalid_apid_setter() {
         let mut packet_id =
-            PacketId::new(PacketType::Tm, false, 0x42).expect("Packet ID creation failed");
+            PacketId::new_checked(PacketType::Tm, false, 0x42).expect("Packet ID creation failed");
         assert!(!packet_id.set_apid(0xffff));
     }
 
     #[test]
     fn test_invalid_seq_count() {
-        let mut psc = PacketSequenceCtrl::new(SequenceFlags::ContinuationSegment, 77)
+        let mut psc = PacketSequenceCtrl::new_checked(SequenceFlags::ContinuationSegment, 77)
             .expect("PSC creation failed");
+        assert_eq!(psc.seq_count(), 77);
         assert!(!psc.set_seq_count(0xffff));
     }
 
     #[test]
     fn test_packet_seq_ctrl() {
-        let mut psc = PacketSequenceCtrl::new(SequenceFlags::ContinuationSegment, 77)
+        let mut psc = PacketSequenceCtrl::new_checked(SequenceFlags::ContinuationSegment, 77)
             .expect("PSC creation failed");
         assert_eq!(psc.raw(), 77);
         let psc_from_raw = PacketSequenceCtrl::from(psc.raw());
@@ -856,16 +1060,18 @@ mod tests {
         assert!(!psc.set_seq_count(2u16.pow(15)));
         assert_eq!(psc.raw(), 77);
 
-        let psc_invalid = PacketSequenceCtrl::new(SequenceFlags::FirstSegment, 0xFFFF);
+        let psc_invalid = PacketSequenceCtrl::new_checked(SequenceFlags::FirstSegment, 0xFFFF);
         assert!(psc_invalid.is_none());
-        let psc_from_new = PacketSequenceCtrl::new(SequenceFlags::ContinuationSegment, 77).unwrap();
+        let psc_from_new =
+            PacketSequenceCtrl::new_checked(SequenceFlags::ContinuationSegment, 77).unwrap();
         assert_eq!(psc_from_new, psc);
     }
 
     #[test]
     #[cfg(feature = "serde")]
     fn test_serde_sph() {
-        let sp_header = SpHeader::tc_unseg(0x42, 12, 0).expect("Error creating SP header");
+        let sp_header =
+            SpHeader::new_for_unseg_tc_checked(0x42, 12, 0).expect("Error creating SP header");
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert!(sp_header.is_tc());
         assert!(!sp_header.sec_header_flag());
@@ -887,7 +1093,8 @@ mod tests {
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert_eq!(sp_header.data_len, 0);
 
-        let sp_header = SpHeader::tm_unseg(0x7, 22, 36).expect("Error creating SP header");
+        let sp_header =
+            SpHeader::new_for_unseg_tm_checked(0x7, 22, 36).expect("Error creating SP header");
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert!(sp_header.is_tm());
         assert!(!sp_header.sec_header_flag());
@@ -901,8 +1108,8 @@ mod tests {
         assert_eq!(sp_header.ccsds_version(), 0b000);
 
         let from_comp_fields = SpHeader::from_composite_fields(
-            PacketId::new(PacketType::Tc, true, 0x42).unwrap(),
-            PacketSequenceCtrl::new(SequenceFlags::Unsegmented, 0x7).unwrap(),
+            PacketId::new(PacketType::Tc, true, 0x42),
+            PacketSequenceCtrl::new(SequenceFlags::Unsegmented, 0x7),
             0,
             None,
         );
@@ -919,7 +1126,7 @@ mod tests {
 
     #[test]
     fn test_setters() {
-        let sp_header = SpHeader::tc(0x42, SequenceFlags::Unsegmented, 25, 0);
+        let sp_header = SpHeader::new_for_tc_checked(0x42, SequenceFlags::Unsegmented, 25, 0);
         assert!(sp_header.is_some());
         let mut sp_header = sp_header.unwrap();
         sp_header.set_apid(0x12);
@@ -937,7 +1144,7 @@ mod tests {
 
     #[test]
     fn test_tc_ctor() {
-        let sp_header = SpHeader::tc(0x42, SequenceFlags::Unsegmented, 25, 0);
+        let sp_header = SpHeader::new_for_tc_checked(0x42, SequenceFlags::Unsegmented, 25, 0);
         assert!(sp_header.is_some());
         let sp_header = sp_header.unwrap();
         verify_sp_fields(PacketType::Tc, &sp_header);
@@ -945,23 +1152,35 @@ mod tests {
 
     #[test]
     fn test_tc_ctor_unseg() {
-        let sp_header = SpHeader::tc_unseg(0x42, 25, 0);
+        let sp_header = SpHeader::new_for_unseg_tc_checked(0x42, 25, 0);
         assert!(sp_header.is_some());
         let sp_header = sp_header.unwrap();
         verify_sp_fields(PacketType::Tc, &sp_header);
     }
 
+    #[test]
+    fn test_tc_ctor_unseg_const() {
+        let sp_header = SpHeader::new_for_unseg_tc(0x42, 25, 0);
+        verify_sp_fields(PacketType::Tc, &sp_header);
+    }
+
     #[test]
     fn test_tm_ctor() {
-        let sp_header = SpHeader::tm(0x42, SequenceFlags::Unsegmented, 25, 0);
+        let sp_header = SpHeader::new_for_tm_checked(0x42, SequenceFlags::Unsegmented, 25, 0);
         assert!(sp_header.is_some());
         let sp_header = sp_header.unwrap();
         verify_sp_fields(PacketType::Tm, &sp_header);
     }
 
+    #[test]
+    fn test_tm_ctor_const() {
+        let sp_header = SpHeader::new_for_tm(0x42, SequenceFlags::Unsegmented, 25, 0);
+        verify_sp_fields(PacketType::Tm, &sp_header);
+    }
+
     #[test]
     fn test_tm_ctor_unseg() {
-        let sp_header = SpHeader::tm_unseg(0x42, 25, 0);
+        let sp_header = SpHeader::new_for_unseg_tm_checked(0x42, 25, 0);
         assert!(sp_header.is_some());
         let sp_header = sp_header.unwrap();
         verify_sp_fields(PacketType::Tm, &sp_header);
@@ -979,8 +1198,8 @@ mod tests {
     fn test_zc_sph() {
         use zerocopy::AsBytes;
 
-        let sp_header =
-            SpHeader::tc_unseg(0x7FF, pow(2, 14) - 1, 0).expect("Error creating SP header");
+        let sp_header = SpHeader::new_for_unseg_tc_checked(0x7FF, pow(2, 14) - 1, 0)
+            .expect("Error creating SP header");
         assert_eq!(sp_header.ptype(), PacketType::Tc);
         assert_eq!(sp_header.apid(), 0x7FF);
         assert_eq!(sp_header.data_len(), 0);
@@ -1027,4 +1246,58 @@ mod tests {
         assert_eq!(sp_header.ptype(), PacketType::Tc);
         assert_eq!(sp_header.data_len(), 0);
     }
+
+    #[test]
+    fn packet_id_ord_partial_ord() {
+        let packet_id_small = PacketId::from(1_u16);
+        let packet_id_larger = PacketId::from(2_u16);
+        assert!(packet_id_small < packet_id_larger);
+        assert!(packet_id_larger > packet_id_small);
+        assert_eq!(
+            packet_id_small.cmp(&packet_id_larger),
+            core::cmp::Ordering::Less
+        );
+    }
+
+    #[test]
+    fn packet_id_hashable() {
+        let mut id_set = HashSet::new();
+        id_set.insert(PacketId::from(1_u16));
+    }
+
+    #[test]
+    fn sp_header_from_apid() {
+        let sp_header = SpHeader::new_from_apid(0x03);
+        assert_eq!(sp_header.apid(), 0x03);
+        assert_eq!(sp_header.data_len(), 0);
+    }
+
+    #[test]
+    fn sp_header_from_apid_checked() {
+        let sp_header = SpHeader::new_from_apid_checked(0x03).unwrap();
+        assert_eq!(sp_header.apid(), 0x03);
+        assert_eq!(sp_header.data_len(), 0);
+    }
+
+    #[cfg(feature = "defmt")]
+    fn is_defmt_format<T: defmt::Format>(_t: T) {}
+
+    #[test]
+    #[cfg(feature = "defmt")]
+    fn test_defmt_format() {
+        is_defmt_format(ByteConversionError::ToSliceTooSmall {
+            found: 1,
+            expected: 2,
+        });
+    }
+
+    #[test]
+    fn test_sp_header_as_vec() {
+        let sp_header = SpHeader::new_for_unseg_tc(0x42, 25, 1);
+        let sp_header_as_vec = sp_header.to_vec();
+        let sp_header_read_back = SpHeader::from_be_bytes(&sp_header_as_vec)
+            .expect("Error reading back SP header")
+            .0;
+        assert_eq!(sp_header, sp_header_read_back);
+    }
 }

src/time/ascii.rs

@@ -2,11 +2,8 @@
 //! [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf) section 3.5 .
 //! See [chrono::DateTime::format] for a usage example of the generated
 //! [chrono::format::DelayedFormat] structs.
-#[cfg(feature = "alloc")]
-use chrono::{
-    format::{DelayedFormat, StrftimeItems},
-    DateTime, Utc,
-};
+#[cfg(all(feature = "alloc", feature = "chrono"))]
+pub use alloc_mod_chrono::*;
 
 /// Tuple of format string and formatted size for time code A.
 ///
@@ -34,36 +31,37 @@ pub const FMT_STR_CODE_B_WITH_SIZE: (&str, usize) = ("%Y-%jT%T%.3f", 21);
 /// Three digits are used for the decimal fraction and a terminator is added at the end.
 pub const FMT_STR_CODE_B_TERMINATED_WITH_SIZE: (&str, usize) = ("%Y-%jT%T%.3fZ", 22);
 
-/// Generates a time code formatter using the [FMT_STR_CODE_A_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-pub fn generate_time_code_a(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
-    date.format(FMT_STR_CODE_A_WITH_SIZE.0)
-}
+#[cfg(all(feature = "alloc", feature = "chrono"))]
+pub mod alloc_mod_chrono {
+    use super::*;
+    use chrono::{
+        format::{DelayedFormat, StrftimeItems},
+        DateTime, Utc,
+    };
 
-/// Generates a time code formatter using the [FMT_STR_CODE_A_TERMINATED_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-pub fn generate_time_code_a_terminated(
-    date: &DateTime<Utc>,
-) -> DelayedFormat<StrftimeItems<'static>> {
-    date.format(FMT_STR_CODE_A_TERMINATED_WITH_SIZE.0)
-}
+    /// Generates a time code formatter using the [FMT_STR_CODE_A_WITH_SIZE] format.
+    pub fn generate_time_code_a(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
+        date.format(FMT_STR_CODE_A_WITH_SIZE.0)
+    }
 
-/// Generates a time code formatter using the [FMT_STR_CODE_B_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-pub fn generate_time_code_b(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
-    date.format(FMT_STR_CODE_B_WITH_SIZE.0)
-}
+    /// Generates a time code formatter using the [FMT_STR_CODE_A_TERMINATED_WITH_SIZE] format.
+    pub fn generate_time_code_a_terminated(
+        date: &DateTime<Utc>,
+    ) -> DelayedFormat<StrftimeItems<'static>> {
+        date.format(FMT_STR_CODE_A_TERMINATED_WITH_SIZE.0)
+    }
 
-/// Generates a time code formatter using the [FMT_STR_CODE_B_TERMINATED_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-pub fn generate_time_code_b_terminated(
-    date: &DateTime<Utc>,
-) -> DelayedFormat<StrftimeItems<'static>> {
-    date.format(FMT_STR_CODE_B_TERMINATED_WITH_SIZE.0)
+    /// Generates a time code formatter using the [FMT_STR_CODE_B_WITH_SIZE] format.
+    pub fn generate_time_code_b(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
+        date.format(FMT_STR_CODE_B_WITH_SIZE.0)
+    }
+
+    /// Generates a time code formatter using the [FMT_STR_CODE_B_TERMINATED_WITH_SIZE] format.
+    pub fn generate_time_code_b_terminated(
+        date: &DateTime<Utc>,
+    ) -> DelayedFormat<StrftimeItems<'static>> {
+        date.format(FMT_STR_CODE_B_TERMINATED_WITH_SIZE.0)
+    }
 }
 
 #[cfg(test)]
@@ -73,25 +71,54 @@ mod tests {
     use std::format;
 
     #[test]
-    fn test_ascii_timestamp_a_unterminated() {
-        let date = Utc::now();
+    fn test_ascii_timestamp_a_unterminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
         let stamp_formatter = generate_time_code_a(&date);
         let stamp = format!("{}", stamp_formatter);
-        let t_sep = stamp.find("T");
+        let t_sep = stamp.find('T');
         assert!(t_sep.is_some());
         assert_eq!(t_sep.unwrap(), 10);
         assert_eq!(stamp.len(), FMT_STR_CODE_A_WITH_SIZE.1);
     }
 
     #[test]
-    fn test_ascii_timestamp_a_terminated() {
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_a_unterminated_now() {
+        let date = Utc::now();
+        let stamp_formatter = generate_time_code_a(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 10);
+        assert_eq!(stamp.len(), FMT_STR_CODE_A_WITH_SIZE.1);
+    }
+
+    #[test]
+    fn test_ascii_timestamp_a_terminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
+        let stamp_formatter = generate_time_code_a_terminated(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 10);
+        let z_terminator = stamp.find('Z');
+        assert!(z_terminator.is_some());
+        assert_eq!(
+            z_terminator.unwrap(),
+            FMT_STR_CODE_A_TERMINATED_WITH_SIZE.1 - 1
+        );
+        assert_eq!(stamp.len(), FMT_STR_CODE_A_TERMINATED_WITH_SIZE.1);
+    }
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_a_terminated_now() {
         let date = Utc::now();
         let stamp_formatter = generate_time_code_a_terminated(&date);
         let stamp = format!("{}", stamp_formatter);
-        let t_sep = stamp.find("T");
+        let t_sep = stamp.find('T');
         assert!(t_sep.is_some());
         assert_eq!(t_sep.unwrap(), 10);
-        let z_terminator = stamp.find("Z");
+        let z_terminator = stamp.find('Z');
         assert!(z_terminator.is_some());
         assert_eq!(
             z_terminator.unwrap(),
@@ -101,25 +128,55 @@ mod tests {
     }
 
     #[test]
-    fn test_ascii_timestamp_b_unterminated() {
-        let date = Utc::now();
+    fn test_ascii_timestamp_b_unterminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
         let stamp_formatter = generate_time_code_b(&date);
         let stamp = format!("{}", stamp_formatter);
-        let t_sep = stamp.find("T");
+        let t_sep = stamp.find('T');
         assert!(t_sep.is_some());
         assert_eq!(t_sep.unwrap(), 8);
         assert_eq!(stamp.len(), FMT_STR_CODE_B_WITH_SIZE.1);
     }
 
     #[test]
-    fn test_ascii_timestamp_b_terminated() {
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_b_unterminated_now() {
+        let date = Utc::now();
+        let stamp_formatter = generate_time_code_b(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 8);
+        assert_eq!(stamp.len(), FMT_STR_CODE_B_WITH_SIZE.1);
+    }
+
+    #[test]
+    fn test_ascii_timestamp_b_terminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
+        let stamp_formatter = generate_time_code_b_terminated(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 8);
+        let z_terminator = stamp.find('Z');
+        assert!(z_terminator.is_some());
+        assert_eq!(
+            z_terminator.unwrap(),
+            FMT_STR_CODE_B_TERMINATED_WITH_SIZE.1 - 1
+        );
+        assert_eq!(stamp.len(), FMT_STR_CODE_B_TERMINATED_WITH_SIZE.1);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_b_terminated_now() {
         let date = Utc::now();
         let stamp_formatter = generate_time_code_b_terminated(&date);
         let stamp = format!("{}", stamp_formatter);
-        let t_sep = stamp.find("T");
+        let t_sep = stamp.find('T');
         assert!(t_sep.is_some());
         assert_eq!(t_sep.unwrap(), 8);
-        let z_terminator = stamp.find("Z");
+        let z_terminator = stamp.find('Z');
         assert!(z_terminator.is_some());
         assert_eq!(
             z_terminator.unwrap(),

src/time/mod.rs

@@ -1,10 +1,12 @@
 //! CCSDS Time Code Formats according to [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
-use crate::{ByteConversionError, SizeMissmatch};
-use chrono::{DateTime, LocalResult, TimeZone, Utc};
+use crate::ByteConversionError;
+#[cfg(feature = "chrono")]
+use chrono::{TimeZone, Utc};
 use core::cmp::Ordering;
 use core::fmt::{Display, Formatter};
-use core::ops::{Add, AddAssign};
+use core::ops::{Add, AddAssign, Sub};
 use core::time::Duration;
+use core::u8;
 
 #[allow(unused_imports)]
 #[cfg(not(feature = "std"))]
@@ -12,10 +14,13 @@ use num_traits::float::FloatCore;
 
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
+
 #[cfg(feature = "std")]
 use std::error::Error;
 #[cfg(feature = "std")]
 use std::time::{SystemTime, SystemTimeError};
+#[cfg(feature = "std")]
+pub use std_mod::*;
 
 pub mod ascii;
 pub mod cds;
@@ -24,10 +29,12 @@ pub mod cuc;
 pub const DAYS_CCSDS_TO_UNIX: i32 = -4383;
 pub const SECONDS_PER_DAY: u32 = 86400;
 pub const MS_PER_DAY: u32 = SECONDS_PER_DAY * 1000;
+pub const NANOS_PER_SECOND: u32 = 1_000_000_000;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub enum CcsdsTimeCodes {
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum CcsdsTimeCode {
     CucCcsdsEpoch = 0b001,
     CucAgencyEpoch = 0b010,
     Cds = 0b100,
@@ -35,16 +42,16 @@ pub enum CcsdsTimeCodes {
     AgencyDefined = 0b110,
 }
 
-impl TryFrom<u8> for CcsdsTimeCodes {
+impl TryFrom<u8> for CcsdsTimeCode {
     type Error = ();
 
     fn try_from(value: u8) -> Result<Self, Self::Error> {
         match value {
-            x if x == CcsdsTimeCodes::CucCcsdsEpoch as u8 => Ok(CcsdsTimeCodes::CucCcsdsEpoch),
-            x if x == CcsdsTimeCodes::CucAgencyEpoch as u8 => Ok(CcsdsTimeCodes::CucAgencyEpoch),
-            x if x == CcsdsTimeCodes::Cds as u8 => Ok(CcsdsTimeCodes::Cds),
-            x if x == CcsdsTimeCodes::Ccs as u8 => Ok(CcsdsTimeCodes::Ccs),
-            x if x == CcsdsTimeCodes::AgencyDefined as u8 => Ok(CcsdsTimeCodes::AgencyDefined),
+            x if x == CcsdsTimeCode::CucCcsdsEpoch as u8 => Ok(CcsdsTimeCode::CucCcsdsEpoch),
+            x if x == CcsdsTimeCode::CucAgencyEpoch as u8 => Ok(CcsdsTimeCode::CucAgencyEpoch),
+            x if x == CcsdsTimeCode::Cds as u8 => Ok(CcsdsTimeCode::Cds),
+            x if x == CcsdsTimeCode::Ccs as u8 => Ok(CcsdsTimeCode::Ccs),
+            x if x == CcsdsTimeCode::AgencyDefined as u8 => Ok(CcsdsTimeCode::AgencyDefined),
             _ => Err(()),
         }
     }
@@ -52,79 +59,54 @@ impl TryFrom<u8> for CcsdsTimeCodes {
 
 /// Retrieve the CCSDS time code from the p-field. If no valid time code identifier is found, the
 /// value of the raw time code identification field is returned.
-pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCodes, u8> {
+pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCode, u8> {
     let raw_bits = (pfield >> 4) & 0b111;
-    CcsdsTimeCodes::try_from(raw_bits).map_err(|_| raw_bits)
+    CcsdsTimeCode::try_from(raw_bits).map_err(|_| raw_bits)
 }
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct DateBeforeCcsdsEpochError(UnixTime);
+
+impl Display for DateBeforeCcsdsEpochError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        write!(f, "date before ccsds epoch: {:?}", self.0)
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for DateBeforeCcsdsEpochError {}
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[non_exhaustive]
 pub enum TimestampError {
-    /// Contains tuple where first value is the expected time code and the second
-    /// value is the found raw value
-    InvalidTimeCode(CcsdsTimeCodes, u8),
-    ByteConversionError(ByteConversionError),
-    CdsError(cds::CdsError),
-    CucError(cuc::CucError),
-    DateBeforeCcsdsEpoch(DateTime<Utc>),
+    InvalidTimeCode { expected: CcsdsTimeCode, found: u8 },
+    ByteConversion(ByteConversionError),
+    Cds(cds::CdsError),
+    Cuc(cuc::CucError),
     CustomEpochNotSupported,
 }
 
-impl From<cds::CdsError> for TimestampError {
-    fn from(e: cds::CdsError) -> Self {
-        TimestampError::CdsError(e)
-    }
-}
-
-impl From<cuc::CucError> for TimestampError {
-    fn from(e: cuc::CucError) -> Self {
-        TimestampError::CucError(e)
-    }
-}
-
-#[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
-#[derive(Debug, Clone)]
-pub enum StdTimestampError {
-    SystemTimeError(SystemTimeError),
-    TimestampError(TimestampError),
-}
-
-#[cfg(feature = "std")]
-impl From<TimestampError> for StdTimestampError {
-    fn from(v: TimestampError) -> Self {
-        Self::TimestampError(v)
-    }
-}
-
-#[cfg(feature = "std")]
-impl From<SystemTimeError> for StdTimestampError {
-    fn from(v: SystemTimeError) -> Self {
-        Self::SystemTimeError(v)
-    }
-}
-
 impl Display for TimestampError {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         match self {
-            TimestampError::InvalidTimeCode(time_code, raw_val) => {
+            TimestampError::InvalidTimeCode { expected, found } => {
                 write!(
                     f,
-                    "invalid raw time code value {raw_val} for time code {time_code:?}"
+                    "invalid raw time code value {found} for time code {expected:?}"
                 )
             }
-            TimestampError::CdsError(e) => {
-                write!(f, "cds error {e}")
+            TimestampError::Cds(e) => {
+                write!(f, "cds error: {e}")
             }
-            TimestampError::CucError(e) => {
-                write!(f, "cuc error {e}")
+            TimestampError::Cuc(e) => {
+                write!(f, "cuc error: {e}")
             }
-            TimestampError::ByteConversionError(e) => {
-                write!(f, "byte conversion error {e}")
-            }
-            TimestampError::DateBeforeCcsdsEpoch(e) => {
-                write!(f, "datetime with date before ccsds epoch: {e}")
+            TimestampError::ByteConversion(e) => {
+                write!(f, "time stamp: {e}")
             }
             TimestampError::CustomEpochNotSupported => {
                 write!(f, "custom epochs are not supported")
@@ -137,16 +119,42 @@ impl Display for TimestampError {
 impl Error for TimestampError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
         match self {
-            TimestampError::ByteConversionError(e) => Some(e),
-            TimestampError::CdsError(e) => Some(e),
-            TimestampError::CucError(e) => Some(e),
+            TimestampError::ByteConversion(e) => Some(e),
+            TimestampError::Cds(e) => Some(e),
+            TimestampError::Cuc(e) => Some(e),
             _ => None,
         }
     }
 }
 
+impl From<cds::CdsError> for TimestampError {
+    fn from(e: cds::CdsError) -> Self {
+        TimestampError::Cds(e)
+    }
+}
+
+impl From<cuc::CucError> for TimestampError {
+    fn from(e: cuc::CucError) -> Self {
+        TimestampError::Cuc(e)
+    }
+}
+
+#[cfg(feature = "std")]
+pub mod std_mod {
+    use crate::time::TimestampError;
+    use std::time::SystemTimeError;
+    use thiserror::Error;
+
+    #[derive(Debug, Clone, Error)]
+    pub enum StdTimestampError {
+        #[error("system time error: {0:?}")]
+        SystemTime(#[from] SystemTimeError),
+        #[error("timestamp error: {0}")]
+        Timestamp(#[from] TimestampError),
+    }
+}
+
 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 pub fn seconds_since_epoch() -> f64 {
     SystemTime::now()
         .duration_since(SystemTime::UNIX_EPOCH)
@@ -158,6 +166,7 @@ pub fn seconds_since_epoch() -> f64 {
 ///
 ///  - CCSDS epoch: 1958-01-01T00:00:00+00:00
 ///  - UNIX Epoch: 1970-01-01T00:00:00+00:00
+#[inline]
 pub const fn unix_to_ccsds_days(unix_days: i64) -> i64 {
     unix_days - DAYS_CCSDS_TO_UNIX as i64
 }
@@ -166,22 +175,24 @@ pub const fn unix_to_ccsds_days(unix_days: i64) -> i64 {
 ///
 ///  - CCSDS epoch: 1958-01-01T00:00:00+00:00
 ///  - UNIX Epoch: 1970-01-01T00:00:00+00:00
+#[inline]
 pub const fn ccsds_to_unix_days(ccsds_days: i64) -> i64 {
     ccsds_days + DAYS_CCSDS_TO_UNIX as i64
 }
 
 /// Similar to [unix_to_ccsds_days] but converts the epoch instead, which is the number of elpased
 /// seconds since the CCSDS and UNIX epoch times.
+#[inline]
 pub const fn unix_epoch_to_ccsds_epoch(unix_epoch: i64) -> i64 {
     unix_epoch - (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)
 }
 
+#[inline]
 pub const fn ccsds_epoch_to_unix_epoch(ccsds_epoch: i64) -> i64 {
     ccsds_epoch + (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 pub fn ms_of_day_using_sysclock() -> u32 {
     ms_of_day(seconds_since_epoch())
 }
@@ -195,21 +206,29 @@ pub fn ms_of_day(seconds_since_epoch: f64) -> u32 {
 }
 
 pub trait TimeWriter {
+    fn len_written(&self) -> usize;
+
     /// Generic function to convert write a timestamp into a raw buffer.
     /// Returns the number of written bytes on success.
     fn write_to_bytes(&self, bytes: &mut [u8]) -> Result<usize, TimestampError>;
+
+    #[cfg(feature = "alloc")]
+    fn to_vec(&self) -> Result<alloc::vec::Vec<u8>, TimestampError> {
+        let mut vec = alloc::vec![0; self.len_written()];
+        self.write_to_bytes(&mut vec)?;
+        Ok(vec)
+    }
 }
 
-pub trait TimeReader {
-    fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError>
-    where
-        Self: Sized;
+pub trait TimeReader: Sized {
+    fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError>;
 }
 
 /// Trait for generic CCSDS time providers.
 ///
-/// The UNIX helper methods and the [Self::date_time] method are not strictly necessary but extremely
+/// The UNIX helper methods and the helper method are not strictly necessary but extremely
 /// practical because they are a very common and simple exchange format for time information.
+/// Therefore, it was decided to keep them in this trait as well.
 pub trait CcsdsTimeProvider {
     fn len_as_bytes(&self) -> usize;
 
@@ -218,148 +237,244 @@ pub trait CcsdsTimeProvider {
     /// entry denotes the length of the pfield and the second entry is the value of the pfield
     /// in big endian format.
     fn p_field(&self) -> (usize, [u8; 2]);
-    fn ccdsd_time_code(&self) -> CcsdsTimeCodes;
+    fn ccdsd_time_code(&self) -> CcsdsTimeCode;
 
-    fn unix_seconds(&self) -> i64;
-    fn subsecond_millis(&self) -> Option<u16>;
-    fn unix_stamp(&self) -> UnixTimestamp {
-        if self.subsecond_millis().is_none() {
-            return UnixTimestamp::new_only_seconds(self.unix_seconds());
-        }
-        UnixTimestamp::const_new(self.unix_seconds(), self.subsecond_millis().unwrap())
+    fn unix_secs(&self) -> i64;
+    fn subsec_nanos(&self) -> u32;
+
+    fn subsec_millis(&self) -> u16 {
+        (self.subsec_nanos() / 1_000_000) as u16
     }
 
-    fn date_time(&self) -> Option<DateTime<Utc>>;
+    fn unix_time(&self) -> UnixTime {
+        UnixTime::new(self.unix_secs(), self.subsec_nanos())
+    }
+
+    #[cfg(feature = "chrono")]
+    fn chrono_date_time(&self) -> chrono::LocalResult<chrono::DateTime<chrono::Utc>> {
+        chrono::Utc.timestamp_opt(self.unix_secs(), self.subsec_nanos())
+    }
+
+    #[cfg(feature = "timelib")]
+    fn timelib_date_time(&self) -> Result<time::OffsetDateTime, time::error::ComponentRange> {
+        Ok(time::OffsetDateTime::from_unix_timestamp(self.unix_secs())?
+            + time::Duration::nanoseconds(self.subsec_nanos().into()))
+    }
 }
 
-/// UNIX timestamp: Elapsed seconds since 1970-01-01T00:00:00+00:00.
+/// UNIX time: Elapsed non-leap seconds since 1970-01-01T00:00:00+00:00 UTC.
 ///
-/// Also can optionally include subsecond millisecond for greater accuracy. Please note that a
-/// subsecond millisecond value of 0 gets converted to [None].
+/// This is a commonly used time format and can therefore also be used as a generic format to
+/// convert other CCSDS time formats to and from. The subsecond precision is in nanoseconds
+/// similarly to other common time formats and libraries.
 #[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct UnixTimestamp {
-    pub unix_seconds: i64,
-    subsecond_millis: Option<u16>,
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct UnixTime {
+    secs: i64,
+    subsec_nanos: u32,
 }
 
-impl UnixTimestamp {
-    /// Returns none if the subsecond millisecond value is larger than 999. 0 is converted to
-    /// a [None] value.
-    pub fn new(unix_seconds: i64, subsec_millis: u16) -> Option<Self> {
-        if subsec_millis > 999 {
+impl UnixTime {
+    /// The UNIX epoch time: 1970-01-01T00:00:00+00:00 UTC.
+    pub const EPOCH: Self = Self {
+        secs: 0,
+        subsec_nanos: 0,
+    };
+
+    /// The minimum possible `UnixTime`.
+    pub const MIN: Self = Self {
+        secs: i64::MIN,
+        subsec_nanos: 0,
+    };
+
+    /// The maximum possible `UnixTime`.
+    pub const MAX: Self = Self {
+        secs: i64::MAX,
+        subsec_nanos: NANOS_PER_SECOND - 1,
+    };
+
+    /// Returns [None] if the subsecond nanosecond value is invalid (larger than fraction of a
+    /// second)
+    pub fn new_checked(unix_seconds: i64, subsec_nanos: u32) -> Option<Self> {
+        if subsec_nanos >= NANOS_PER_SECOND {
             return None;
         }
-        Some(Self::const_new(unix_seconds, subsec_millis))
+        Some(Self::new(unix_seconds, subsec_nanos))
     }
 
-    /// Like [Self::new] but const. Panics if the subsecond value is larger than 999.
-    pub const fn const_new(unix_seconds: i64, subsec_millis: u16) -> Self {
-        if subsec_millis > 999 {
-            panic!("subsec milliseconds exceeds 999");
+    /// Returns [None] if the subsecond millisecond value is invalid (larger than fraction of a
+    /// second)
+    pub fn new_subsec_millis_checked(unix_seconds: i64, subsec_millis: u16) -> Option<Self> {
+        if subsec_millis >= 1000 {
+            return None;
+        }
+        Self::new_checked(unix_seconds, subsec_millis as u32 * 1_000_000)
+    }
+
+    /// This function will panic if the subsecond value is larger than the fraction of a second.
+    /// Use [Self::new_checked] if you want to handle this case without a panic.
+    pub const fn new(unix_seconds: i64, subsecond_nanos: u32) -> Self {
+        if subsecond_nanos >= NANOS_PER_SECOND {
+            panic!("invalid subsecond nanos value");
         }
-        let subsecond_millis = if subsec_millis == 0 {
-            None
-        } else {
-            Some(subsec_millis)
-        };
         Self {
-            unix_seconds,
-            subsecond_millis,
+            secs: unix_seconds,
+            subsec_nanos: subsecond_nanos,
         }
     }
 
-    pub fn new_only_seconds(unix_seconds: i64) -> Self {
+    /// This function will panic if the subsecond value is larger than the fraction of a second.
+    /// Use [Self::new_subsec_millis_checked] if you want to handle this case without a panic.
+    pub const fn new_subsec_millis(unix_seconds: i64, subsecond_millis: u16) -> Self {
+        if subsecond_millis >= 1000 {
+            panic!("invalid subsecond millisecond value");
+        }
         Self {
-            unix_seconds,
-            subsecond_millis: None,
+            secs: unix_seconds,
+            subsec_nanos: subsecond_millis as u32 * 1_000_000,
         }
     }
 
-    pub fn subsecond_millis(&self) -> Option<u16> {
-        self.subsecond_millis
-    }
-
-    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
-    pub fn from_now() -> Result<Self, SystemTimeError> {
-        let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
-        let epoch = now.as_secs();
-        Ok(Self::const_new(epoch as i64, now.subsec_millis() as u16))
+    pub fn new_only_secs(unix_seconds: i64) -> Self {
+        Self {
+            secs: unix_seconds,
+            subsec_nanos: 0,
+        }
     }
 
     #[inline]
-    pub fn unix_seconds_f64(&self) -> f64 {
-        let mut secs = self.unix_seconds as f64;
-        if let Some(subsec_millis) = self.subsecond_millis {
-            secs += subsec_millis as f64 / 1000.0;
-        }
-        secs
+    pub fn subsec_millis(&self) -> u16 {
+        (self.subsec_nanos / 1_000_000) as u16
     }
 
-    pub fn as_date_time(&self) -> LocalResult<DateTime<Utc>> {
-        Utc.timestamp_opt(
-            self.unix_seconds,
-            self.subsecond_millis.unwrap_or(0) as u32 * 10_u32.pow(6),
-        )
+    pub fn subsec_nanos(&self) -> u32 {
+        self.subsec_nanos
+    }
+
+    #[cfg(feature = "std")]
+    pub fn now() -> Result<Self, SystemTimeError> {
+        let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
+        let epoch = now.as_secs();
+        Ok(Self::new(epoch as i64, now.subsec_nanos()))
+    }
+
+    #[inline]
+    pub fn unix_secs_f64(&self) -> f64 {
+        self.secs as f64 + (self.subsec_nanos as f64 / 1_000_000_000.0)
+    }
+
+    pub fn as_secs(&self) -> i64 {
+        self.secs
+    }
+
+    #[cfg(feature = "chrono")]
+    pub fn chrono_date_time(&self) -> chrono::LocalResult<chrono::DateTime<chrono::Utc>> {
+        Utc.timestamp_opt(self.secs, self.subsec_nanos)
+    }
+
+    #[cfg(feature = "timelib")]
+    pub fn timelib_date_time(&self) -> Result<time::OffsetDateTime, time::error::ComponentRange> {
+        Ok(time::OffsetDateTime::from_unix_timestamp(self.as_secs())?
+            + time::Duration::nanoseconds(self.subsec_nanos().into()))
+    }
+
+    // Calculate the difference in milliseconds between two UnixTimestamps
+    pub fn diff_in_millis(&self, other: &UnixTime) -> Option<i64> {
+        let seconds_difference = self.secs.checked_sub(other.secs)?;
+        // Convert seconds difference to milliseconds
+        let milliseconds_difference = seconds_difference.checked_mul(1000)?;
+
+        // Calculate the difference in subsecond milliseconds directly
+        let subsecond_difference_nanos = self.subsec_nanos as i64 - other.subsec_nanos as i64;
+
+        // Combine the differences
+        Some(milliseconds_difference + (subsecond_difference_nanos / 1_000_000))
     }
 }
 
-impl From<DateTime<Utc>> for UnixTimestamp {
-    fn from(value: DateTime<Utc>) -> Self {
-        Self::const_new(value.timestamp(), value.timestamp_subsec_millis() as u16)
+#[cfg(feature = "chrono")]
+impl From<chrono::DateTime<chrono::Utc>> for UnixTime {
+    fn from(value: chrono::DateTime<chrono::Utc>) -> Self {
+        Self::new(value.timestamp(), value.timestamp_subsec_nanos())
     }
 }
 
-impl PartialOrd for UnixTimestamp {
+#[cfg(feature = "timelib")]
+impl From<time::OffsetDateTime> for UnixTime {
+    fn from(value: time::OffsetDateTime) -> Self {
+        Self::new(value.unix_timestamp(), value.nanosecond())
+    }
+}
+
+impl PartialOrd for UnixTime {
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for UnixTime {
+    fn cmp(&self, other: &Self) -> Ordering {
         if self == other {
-            return Some(Ordering::Equal);
+            return Ordering::Equal;
         }
-        match self.unix_seconds.cmp(&other.unix_seconds) {
-            Ordering::Less => return Some(Ordering::Less),
-            Ordering::Greater => return Some(Ordering::Greater),
+        match self.secs.cmp(&other.secs) {
+            Ordering::Less => return Ordering::Less,
+            Ordering::Greater => return Ordering::Greater,
             _ => (),
         }
 
-        match self
-            .subsecond_millis()
-            .unwrap_or(0)
-            .cmp(&other.subsecond_millis().unwrap_or(0))
-        {
+        match self.subsec_millis().cmp(&other.subsec_millis()) {
             Ordering::Less => {
-                return if self.unix_seconds < 0 {
-                    Some(Ordering::Greater)
+                return if self.secs < 0 {
+                    Ordering::Greater
                 } else {
-                    Some(Ordering::Less)
+                    Ordering::Less
                 }
             }
             Ordering::Greater => {
-                return if self.unix_seconds < 0 {
-                    Some(Ordering::Less)
+                return if self.secs < 0 {
+                    Ordering::Less
                 } else {
-                    Some(Ordering::Greater)
+                    Ordering::Greater
                 }
             }
             Ordering::Equal => (),
         }
-        Some(Ordering::Equal)
+        Ordering::Equal
     }
 }
 
-impl Ord for UnixTimestamp {
-    fn cmp(&self, other: &Self) -> Ordering {
-        PartialOrd::partial_cmp(self, other).unwrap()
+/// Difference between two UNIX timestamps. The [Duration] type can not contain negative durations,
+/// so the sign information is supplied separately.
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub struct StampDiff {
+    pub positive_duration: bool,
+    pub duration_absolute: Duration,
+}
+
+impl Sub for UnixTime {
+    type Output = Option<StampDiff>;
+
+    fn sub(self, rhs: Self) -> Self::Output {
+        let difference = self.diff_in_millis(&rhs)?;
+        Some(if difference < 0 {
+            StampDiff {
+                positive_duration: false,
+                duration_absolute: Duration::from_millis(-difference as u64),
+            }
+        } else {
+            StampDiff {
+                positive_duration: true,
+                duration_absolute: Duration::from_millis(difference as u64),
+            }
+        })
     }
 }
 
-fn get_new_stamp_after_addition(
-    current_stamp: &UnixTimestamp,
-    duration: Duration,
-) -> UnixTimestamp {
-    let mut new_subsec_millis =
-        current_stamp.subsecond_millis().unwrap_or(0) + duration.subsec_millis() as u16;
-    let mut new_unix_seconds = current_stamp.unix_seconds;
+fn get_new_stamp_after_addition(current_stamp: &UnixTime, duration: Duration) -> UnixTime {
+    let mut new_subsec_nanos = current_stamp.subsec_nanos() + duration.subsec_nanos();
+    let mut new_unix_seconds = current_stamp.secs;
     let mut increment_seconds = |value: u32| {
         if new_unix_seconds < 0 {
             new_unix_seconds = new_unix_seconds
@@ -371,8 +486,8 @@ fn get_new_stamp_after_addition(
                 .expect("new unix seconds would exceed i64::MAX");
         }
     };
-    if new_subsec_millis >= 1000 {
-        new_subsec_millis -= 1000;
+    if new_subsec_nanos >= 1_000_000_000 {
+        new_subsec_nanos -= 1_000_000_000;
         increment_seconds(1);
     }
     increment_seconds(
@@ -381,7 +496,7 @@ fn get_new_stamp_after_addition(
             .try_into()
             .expect("duration seconds exceeds u32::MAX"),
     );
-    UnixTimestamp::const_new(new_unix_seconds, new_subsec_millis)
+    UnixTime::new(new_unix_seconds, new_subsec_nanos)
 }
 
 /// Please note that this operation will panic on the following conditions:
@@ -389,7 +504,7 @@ fn get_new_stamp_after_addition(
 /// - Unix seconds after subtraction for stamps before the unix epoch exceeds [i64::MIN].
 /// - Unix seconds after addition  exceeds [i64::MAX].
 /// - Seconds from duration to add exceeds [u32::MAX].
-impl AddAssign<Duration> for UnixTimestamp {
+impl AddAssign<Duration> for UnixTime {
     fn add_assign(&mut self, duration: Duration) {
         *self = get_new_stamp_after_addition(self, duration);
     }
@@ -400,7 +515,7 @@ impl AddAssign<Duration> for UnixTimestamp {
 /// - Unix seconds after subtraction for stamps before the unix epoch exceeds [i64::MIN].
 /// - Unix seconds after addition  exceeds [i64::MAX].
 /// - Unix seconds exceeds [u32::MAX].
-impl Add<Duration> for UnixTimestamp {
+impl Add<Duration> for UnixTime {
     type Output = Self;
 
     fn add(self, duration: Duration) -> Self::Output {
@@ -408,8 +523,8 @@ impl Add<Duration> for UnixTimestamp {
     }
 }
 
-impl Add<Duration> for &UnixTimestamp {
-    type Output = UnixTimestamp;
+impl Add<Duration> for &UnixTime {
+    type Output = UnixTime;
 
     fn add(self, duration: Duration) -> Self::Output {
         get_new_stamp_after_addition(self, duration)
@@ -418,7 +533,16 @@ impl Add<Duration> for &UnixTimestamp {
 
 #[cfg(all(test, feature = "std"))]
 mod tests {
-    use super::*;
+    use alloc::string::ToString;
+    use chrono::{Datelike, Timelike};
+    use std::{format, println};
+
+    use super::{cuc::CucError, *};
+
+    #[allow(dead_code)]
+    const UNIX_STAMP_CONST: UnixTime = UnixTime::new(5, 999_999_999);
+    #[allow(dead_code)]
+    const UNIX_STAMP_CONST_2: UnixTime = UnixTime::new_subsec_millis(5, 999);
 
     #[test]
     fn test_days_conversion() {
@@ -427,12 +551,22 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_get_current_time() {
         let sec_floats = seconds_since_epoch();
         assert!(sec_floats > 0.0);
     }
 
     #[test]
+    fn test_ms_of_day() {
+        let ms = ms_of_day(0.0);
+        assert_eq!(ms, 0);
+        let ms = ms_of_day(5.0);
+        assert_eq!(ms, 5000);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_ccsds_epoch() {
         let now = SystemTime::now()
             .duration_since(SystemTime::UNIX_EPOCH)
@@ -447,29 +581,29 @@ mod tests {
 
     #[test]
     fn basic_unix_stamp_test() {
-        let stamp = UnixTimestamp::new_only_seconds(-200);
-        assert_eq!(stamp.unix_seconds, -200);
-        assert!(stamp.subsecond_millis().is_none());
-        let stamp = UnixTimestamp::new_only_seconds(250);
-        assert_eq!(stamp.unix_seconds, 250);
-        assert!(stamp.subsecond_millis().is_none());
+        let stamp = UnixTime::new_only_secs(-200);
+        assert_eq!(stamp.secs, -200);
+        assert_eq!(stamp.subsec_millis(), 0);
+        let stamp = UnixTime::new_only_secs(250);
+        assert_eq!(stamp.secs, 250);
+        assert_eq!(stamp.subsec_millis(), 0);
     }
 
     #[test]
     fn basic_float_unix_stamp_test() {
-        let stamp = UnixTimestamp::new(500, 600).unwrap();
-        assert!(stamp.subsecond_millis.is_some());
-        assert_eq!(stamp.unix_seconds, 500);
-        let subsec_millis = stamp.subsecond_millis().unwrap();
+        let stamp = UnixTime::new_subsec_millis_checked(500, 600).unwrap();
+        assert_eq!(stamp.secs, 500);
+        let subsec_millis = stamp.subsec_millis();
         assert_eq!(subsec_millis, 600);
-        assert!((500.6 - stamp.unix_seconds_f64()).abs() < 0.0001);
+        println!("{:?}", (500.6 - stamp.unix_secs_f64()).to_string());
+        assert!((500.6 - stamp.unix_secs_f64()).abs() < 0.0001);
     }
 
     #[test]
     fn test_ord_larger() {
-        let stamp0 = UnixTimestamp::new_only_seconds(5);
-        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        let stamp0 = UnixTime::new_only_secs(5);
+        let stamp1 = UnixTime::new_subsec_millis_checked(5, 500).unwrap();
+        let stamp2 = UnixTime::new_only_secs(6);
         assert!(stamp1 > stamp0);
         assert!(stamp2 > stamp0);
         assert!(stamp2 > stamp1);
@@ -477,9 +611,9 @@ mod tests {
 
     #[test]
     fn test_ord_smaller() {
-        let stamp0 = UnixTimestamp::new_only_seconds(5);
-        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        let stamp0 = UnixTime::new_only_secs(5);
+        let stamp1 = UnixTime::new_subsec_millis_checked(5, 500).unwrap();
+        let stamp2 = UnixTime::new_only_secs(6);
         assert!(stamp0 < stamp1);
         assert!(stamp0 < stamp2);
         assert!(stamp1 < stamp2);
@@ -487,9 +621,9 @@ mod tests {
 
     #[test]
     fn test_ord_larger_neg_numbers() {
-        let stamp0 = UnixTimestamp::new_only_seconds(-5);
-        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        let stamp0 = UnixTime::new_only_secs(-5);
+        let stamp1 = UnixTime::new_subsec_millis_checked(-5, 500).unwrap();
+        let stamp2 = UnixTime::new_only_secs(-6);
         assert!(stamp0 > stamp1);
         assert!(stamp0 > stamp2);
         assert!(stamp1 > stamp2);
@@ -499,9 +633,9 @@ mod tests {
 
     #[test]
     fn test_ord_smaller_neg_numbers() {
-        let stamp0 = UnixTimestamp::new_only_seconds(-5);
-        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        let stamp0 = UnixTime::new_only_secs(-5);
+        let stamp1 = UnixTime::new_subsec_millis_checked(-5, 500).unwrap();
+        let stamp2 = UnixTime::new_only_secs(-6);
         assert!(stamp2 < stamp1);
         assert!(stamp2 < stamp0);
         assert!(stamp1 < stamp0);
@@ -509,10 +643,11 @@ mod tests {
         assert!(stamp2 <= stamp1);
     }
 
+    #[allow(clippy::nonminimal_bool)]
     #[test]
     fn test_eq() {
-        let stamp0 = UnixTimestamp::new(5, 0).unwrap();
-        let stamp1 = UnixTimestamp::new_only_seconds(5);
+        let stamp0 = UnixTime::new(5, 0);
+        let stamp1 = UnixTime::new_only_secs(5);
         assert_eq!(stamp0, stamp1);
         assert!(stamp0 <= stamp1);
         assert!(stamp0 >= stamp1);
@@ -522,32 +657,115 @@ mod tests {
 
     #[test]
     fn test_addition() {
-        let mut stamp0 = UnixTimestamp::new_only_seconds(1);
+        let mut stamp0 = UnixTime::new_only_secs(1);
         stamp0 += Duration::from_secs(5);
-        assert_eq!(stamp0.unix_seconds, 6);
-        assert!(stamp0.subsecond_millis().is_none());
+        assert_eq!(stamp0.as_secs(), 6);
+        assert_eq!(stamp0.subsec_millis(), 0);
         let stamp1 = stamp0 + Duration::from_millis(500);
-        assert_eq!(stamp1.unix_seconds, 6);
-        assert!(stamp1.subsecond_millis().is_some());
-        assert_eq!(stamp1.subsecond_millis().unwrap(), 500);
+        assert_eq!(stamp1.secs, 6);
+        assert_eq!(stamp1.subsec_millis(), 500);
     }
 
     #[test]
     fn test_addition_on_ref() {
-        let stamp0 = &UnixTimestamp::new(20, 500).unwrap();
+        let stamp0 = &UnixTime::new_subsec_millis_checked(20, 500).unwrap();
         let stamp1 = stamp0 + Duration::from_millis(2500);
-        assert_eq!(stamp1.unix_seconds, 23);
-        assert!(stamp1.subsecond_millis().is_none());
+        assert_eq!(stamp1.secs, 23);
+        assert_eq!(stamp1.subsec_millis(), 0);
+    }
+
+    #[test]
+    fn test_as_dt() {
+        let stamp = UnixTime::new_only_secs(0);
+        let dt = stamp.chrono_date_time().unwrap();
+        assert_eq!(dt.year(), 1970);
+        assert_eq!(dt.month(), 1);
+        assert_eq!(dt.day(), 1);
+        assert_eq!(dt.hour(), 0);
+        assert_eq!(dt.minute(), 0);
+        assert_eq!(dt.second(), 0);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_from_now() {
+        let stamp_now = UnixTime::now().unwrap();
+        let dt_now = stamp_now.chrono_date_time().unwrap();
+        assert!(dt_now.year() >= 2020);
+    }
+
+    #[test]
+    fn test_stamp_diff_positive_0() {
+        let stamp_later = UnixTime::new(2, 0);
+        let StampDiff {
+            positive_duration,
+            duration_absolute,
+        } = (stamp_later - UnixTime::new(1, 0)).expect("stamp diff error");
+        assert!(positive_duration);
+        assert_eq!(duration_absolute, Duration::from_secs(1));
+    }
+
+    #[test]
+    fn test_stamp_diff_positive_1() {
+        let stamp_later = UnixTime::new(3, 800 * 1_000_000);
+        let stamp_earlier = UnixTime::new_subsec_millis_checked(1, 900).unwrap();
+        let StampDiff {
+            positive_duration,
+            duration_absolute,
+        } = (stamp_later - stamp_earlier).expect("stamp diff error");
+        assert!(positive_duration);
+        assert_eq!(duration_absolute, Duration::from_millis(1900));
+    }
+
+    #[test]
+    fn test_stamp_diff_negative() {
+        let stamp_later = UnixTime::new_subsec_millis_checked(3, 800).unwrap();
+        let stamp_earlier = UnixTime::new_subsec_millis_checked(1, 900).unwrap();
+        let StampDiff {
+            positive_duration,
+            duration_absolute,
+        } = (stamp_earlier - stamp_later).expect("stamp diff error");
+        assert!(!positive_duration);
+        assert_eq!(duration_absolute, Duration::from_millis(1900));
     }
 
     #[test]
     fn test_addition_spillover() {
-        let mut stamp0 = UnixTimestamp::new(1, 900).unwrap();
+        let mut stamp0 = UnixTime::new_subsec_millis_checked(1, 900).unwrap();
         stamp0 += Duration::from_millis(100);
-        assert_eq!(stamp0.unix_seconds, 2);
-        assert!(stamp0.subsecond_millis().is_none());
+        assert_eq!(stamp0.secs, 2);
+        assert_eq!(stamp0.subsec_millis(), 0);
         stamp0 += Duration::from_millis(1100);
-        assert_eq!(stamp0.unix_seconds, 3);
-        assert_eq!(stamp0.subsecond_millis().unwrap(), 100);
+        assert_eq!(stamp0.secs, 3);
+        assert_eq!(stamp0.subsec_millis(), 100);
+    }
+
+    #[test]
+    fn test_cuc_error_printout() {
+        let cuc_error = CucError::InvalidCounterWidth(12);
+        let stamp_error = TimestampError::from(cuc_error);
+        assert_eq!(stamp_error.to_string(), format!("cuc error: {cuc_error}"));
+    }
+
+    #[test]
+    #[cfg(feature = "timelib")]
+    fn test_unix_stamp_as_timelib_datetime() {
+        let stamp_epoch = UnixTime::EPOCH;
+        let timelib_dt = stamp_epoch.timelib_date_time().unwrap();
+        assert_eq!(timelib_dt.year(), 1970);
+        assert_eq!(timelib_dt.month(), time::Month::January);
+        assert_eq!(timelib_dt.day(), 1);
+        assert_eq!(timelib_dt.hour(), 0);
+        assert_eq!(timelib_dt.minute(), 0);
+        assert_eq!(timelib_dt.second(), 0);
+    }
+
+    #[test]
+    #[cfg(feature = "timelib")]
+    fn test_unix_stamp_from_timelib_datetime() {
+        let timelib_dt = time::OffsetDateTime::UNIX_EPOCH;
+        let unix_time = UnixTime::from(timelib_dt);
+        let timelib_converted_back = unix_time.timelib_date_time().unwrap();
+        assert_eq!(timelib_dt, timelib_converted_back);
     }
 }

src/tm.rs

@@ -1,715 +0,0 @@
-//! This module contains all components required to create a ECSS PUS C telemetry packets according
-//! to [ECSS-E-ST-70-41C](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
-use crate::ecss::{
-    ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
-    verify_crc16_from_raw, CrcType, PusError, PusPacket, PusVersion, CRC_CCITT_FALSE,
-};
-use crate::{
-    ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SizeMissmatch, SpHeader,
-    CCSDS_HEADER_LEN,
-};
-use core::mem::size_of;
-#[cfg(feature = "serde")]
-use serde::{Deserialize, Serialize};
-use zerocopy::AsBytes;
-
-#[cfg(feature = "alloc")]
-use alloc::vec::Vec;
-use delegate::delegate;
-
-/// Length without timestamp
-pub const PUC_TM_MIN_SEC_HEADER_LEN: usize = 7;
-pub const PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA: usize =
-    CCSDS_HEADER_LEN + PUC_TM_MIN_SEC_HEADER_LEN + size_of::<CrcType>();
-
-pub trait GenericPusTmSecondaryHeader {
-    fn pus_version(&self) -> PusVersion;
-    fn sc_time_ref_status(&self) -> u8;
-    fn service(&self) -> u8;
-    fn subservice(&self) -> u8;
-    fn msg_counter(&self) -> u16;
-    fn dest_id(&self) -> u16;
-}
-
-pub mod zc {
-    use super::GenericPusTmSecondaryHeader;
-    use crate::ecss::{PusError, PusVersion};
-    use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
-
-    #[derive(FromBytes, AsBytes, Unaligned)]
-    #[repr(C)]
-    pub struct PusTmSecHeaderWithoutTimestamp {
-        pus_version_and_sc_time_ref_status: u8,
-        service: u8,
-        subservice: u8,
-        msg_counter: U16<NetworkEndian>,
-        dest_id: U16<NetworkEndian>,
-    }
-
-    pub struct PusTmSecHeader<'slice> {
-        pub(crate) zc_header: PusTmSecHeaderWithoutTimestamp,
-        pub(crate) timestamp: Option<&'slice [u8]>,
-    }
-
-    impl TryFrom<crate::tm::PusTmSecondaryHeader<'_>> for PusTmSecHeaderWithoutTimestamp {
-        type Error = PusError;
-        fn try_from(header: crate::tm::PusTmSecondaryHeader) -> Result<Self, Self::Error> {
-            if header.pus_version != PusVersion::PusC {
-                return Err(PusError::VersionNotSupported(header.pus_version));
-            }
-            Ok(PusTmSecHeaderWithoutTimestamp {
-                pus_version_and_sc_time_ref_status: ((header.pus_version as u8) << 4)
-                    | header.sc_time_ref_status,
-                service: header.service,
-                subservice: header.subservice,
-                msg_counter: U16::from(header.msg_counter),
-                dest_id: U16::from(header.dest_id),
-            })
-        }
-    }
-
-    impl PusTmSecHeaderWithoutTimestamp {
-        pub fn write_to_bytes(&self, slice: &mut [u8]) -> Option<()> {
-            self.write_to(slice)
-        }
-
-        pub fn from_bytes(slice: &[u8]) -> Option<Self> {
-            Self::read_from(slice)
-        }
-    }
-
-    impl GenericPusTmSecondaryHeader for PusTmSecHeaderWithoutTimestamp {
-        fn pus_version(&self) -> PusVersion {
-            PusVersion::try_from(self.pus_version_and_sc_time_ref_status >> 4 & 0b1111)
-                .unwrap_or(PusVersion::Invalid)
-        }
-
-        fn sc_time_ref_status(&self) -> u8 {
-            self.pus_version_and_sc_time_ref_status & 0b1111
-        }
-
-        fn service(&self) -> u8 {
-            self.service
-        }
-
-        fn subservice(&self) -> u8 {
-            self.subservice
-        }
-
-        fn msg_counter(&self) -> u16 {
-            self.msg_counter.get()
-        }
-
-        fn dest_id(&self) -> u16 {
-            self.dest_id.get()
-        }
-    }
-}
-
-#[derive(PartialEq, Eq, Copy, Clone, Debug)]
-#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct PusTmSecondaryHeader<'stamp> {
-    pus_version: PusVersion,
-    pub sc_time_ref_status: u8,
-    pub service: u8,
-    pub subservice: u8,
-    pub msg_counter: u16,
-    pub dest_id: u16,
-    pub timestamp: Option<&'stamp [u8]>,
-}
-
-impl<'stamp> PusTmSecondaryHeader<'stamp> {
-    pub fn new_simple(service: u8, subservice: u8, timestamp: &'stamp [u8]) -> Self {
-        Self::new(service, subservice, 0, 0, Some(timestamp))
-    }
-
-    /// Like [Self::new_simple] but without a timestamp.
-    pub fn new_simple_no_timestamp(service: u8, subservice: u8) -> Self {
-        Self::new(service, subservice, 0, 0, None)
-    }
-
-    pub fn new(
-        service: u8,
-        subservice: u8,
-        msg_counter: u16,
-        dest_id: u16,
-        timestamp: Option<&'stamp [u8]>,
-    ) -> Self {
-        PusTmSecondaryHeader {
-            pus_version: PusVersion::PusC,
-            sc_time_ref_status: 0,
-            service,
-            subservice,
-            msg_counter,
-            dest_id,
-            timestamp,
-        }
-    }
-}
-
-impl GenericPusTmSecondaryHeader for PusTmSecondaryHeader<'_> {
-    fn pus_version(&self) -> PusVersion {
-        self.pus_version
-    }
-
-    fn sc_time_ref_status(&self) -> u8 {
-        self.sc_time_ref_status
-    }
-
-    fn service(&self) -> u8 {
-        self.service
-    }
-
-    fn subservice(&self) -> u8 {
-        self.subservice
-    }
-
-    fn msg_counter(&self) -> u16 {
-        self.msg_counter
-    }
-
-    fn dest_id(&self) -> u16 {
-        self.dest_id
-    }
-}
-
-impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice> {
-    type Error = ();
-
-    fn try_from(sec_header: zc::PusTmSecHeader<'slice>) -> Result<Self, Self::Error> {
-        Ok(PusTmSecondaryHeader {
-            pus_version: sec_header.zc_header.pus_version(),
-            sc_time_ref_status: sec_header.zc_header.sc_time_ref_status(),
-            service: sec_header.zc_header.service(),
-            subservice: sec_header.zc_header.subservice(),
-            msg_counter: sec_header.zc_header.msg_counter(),
-            dest_id: sec_header.zc_header.dest_id(),
-            timestamp: sec_header.timestamp,
-        })
-    }
-}
-
-/// This class models the PUS C telemetry packet. It is the primary data structure to generate the
-/// raw byte representation of PUS telemetry or to deserialize from one from raw bytes.
-///
-/// This class also derives the [serde::Serialize] and [serde::Deserialize] trait if the [serde]
-/// feature is used which allows to send around TM packets in a raw byte format using a serde
-/// provider like [postcard](https://docs.rs/postcard/latest/postcard/).
-///
-/// There is no spare bytes support yet.
-///
-/// # Lifetimes
-///
-/// * `'raw_data` - If the TM is not constructed from a raw slice, this will be the life time of
-///    a buffer where the user provided time stamp and source data will be serialized into. If it
-///    is, this is the lifetime of the raw byte slice it is constructed from.
-#[derive(Eq, Debug, Copy, Clone)]
-#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct PusTm<'raw_data> {
-    pub sp_header: SpHeader,
-    pub sec_header: PusTmSecondaryHeader<'raw_data>,
-    /// If this is set to false, a manual call to [PusTm::calc_own_crc16] or
-    /// [PusTm::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
-    pub calc_crc_on_serialization: bool,
-    #[cfg_attr(feature = "serde", serde(skip))]
-    raw_data: Option<&'raw_data [u8]>,
-    source_data: Option<&'raw_data [u8]>,
-    crc16: Option<u16>,
-}
-
-impl<'raw_data> PusTm<'raw_data> {
-    /// Generates a new struct instance.
-    ///
-    /// # Arguments
-    ///
-    /// * `sp_header` - Space packet header information. The correct packet type will be set
-    ///     automatically
-    /// * `sec_header` - Information contained in the secondary header, including the service
-    ///     and subservice type
-    /// * `app_data` - Custom application data
-    /// * `set_ccsds_len` - Can be used to automatically update the CCSDS space packet data length
-    ///     field. If this is not set to true, [PusTm::update_ccsds_data_len] can be called to set
-    ///     the correct value to this field manually
-    pub fn new(
-        sp_header: &mut SpHeader,
-        sec_header: PusTmSecondaryHeader<'raw_data>,
-        source_data: Option<&'raw_data [u8]>,
-        set_ccsds_len: bool,
-    ) -> Self {
-        sp_header.set_packet_type(PacketType::Tm);
-        sp_header.set_sec_header_flag();
-        let mut pus_tm = PusTm {
-            sp_header: *sp_header,
-            raw_data: None,
-            source_data,
-            sec_header,
-            calc_crc_on_serialization: true,
-            crc16: None,
-        };
-        if set_ccsds_len {
-            pus_tm.update_ccsds_data_len();
-        }
-        pus_tm
-    }
-
-    pub fn len_packed(&self) -> usize {
-        let mut length = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA;
-        if let Some(timestamp) = self.sec_header.timestamp {
-            length += timestamp.len();
-        }
-        if let Some(src_data) = self.source_data {
-            length += src_data.len();
-        }
-        length
-    }
-
-    pub fn timestamp(&self) -> Option<&'raw_data [u8]> {
-        self.sec_header.timestamp
-    }
-
-    pub fn source_data(&self) -> Option<&'raw_data [u8]> {
-        self.source_data
-    }
-
-    pub fn set_dest_id(&mut self, dest_id: u16) {
-        self.sec_header.dest_id = dest_id;
-    }
-
-    pub fn set_msg_counter(&mut self, msg_counter: u16) {
-        self.sec_header.msg_counter = msg_counter
-    }
-
-    pub fn set_sc_time_ref_status(&mut self, sc_time_ref_status: u8) {
-        self.sec_header.sc_time_ref_status = sc_time_ref_status & 0b1111;
-    }
-
-    sp_header_impls!();
-
-    /// This is called automatically if the `set_ccsds_len` argument in the [PusTm::new] call was
-    /// used.
-    /// If this was not done or the time stamp or source data is set or changed after construction,
-    /// this function needs to be called to ensure that the data length field of the CCSDS header
-    /// is set correctly
-    pub fn update_ccsds_data_len(&mut self) {
-        self.sp_header.data_len =
-            self.len_packed() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
-    }
-
-    /// This function should be called before the TM packet is serialized if
-    /// [PusTm.calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
-    pub fn calc_own_crc16(&mut self) {
-        let mut digest = CRC_CCITT_FALSE.digest();
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        digest.update(sph_zc.as_bytes());
-        let pus_tc_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        digest.update(pus_tc_header.as_bytes());
-        if let Some(stamp) = self.sec_header.timestamp {
-            digest.update(stamp);
-        }
-        if let Some(src_data) = self.source_data {
-            digest.update(src_data);
-        }
-        self.crc16 = Some(digest.finalize())
-    }
-
-    /// This helper function calls both [PusTm.update_ccsds_data_len] and [PusTm.calc_own_crc16]
-    pub fn update_packet_fields(&mut self) {
-        self.update_ccsds_data_len();
-        self.calc_own_crc16();
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = 0;
-        let total_size = self.len_packed();
-        if total_size > slice.len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: slice.len(),
-                expected: total_size,
-            })
-            .into());
-        }
-        self.sp_header
-            .write_to_be_bytes(&mut slice[0..CCSDS_HEADER_LEN])?;
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header_len = size_of::<zc::PusTmSecHeaderWithoutTimestamp>();
-        let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        sec_header
-            .write_to_bytes(&mut slice[curr_idx..curr_idx + sec_header_len])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-        curr_idx += sec_header_len;
-        if let Some(timestamp) = self.sec_header.timestamp {
-            let timestamp_len = timestamp.len();
-            slice[curr_idx..curr_idx + timestamp_len].copy_from_slice(timestamp);
-            curr_idx += timestamp_len;
-        }
-        if let Some(src_data) = self.source_data {
-            slice[curr_idx..curr_idx + src_data.len()].copy_from_slice(src_data);
-            curr_idx += src_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            0,
-            curr_idx,
-            slice,
-        )?;
-        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
-    /// Append the raw PUS byte representation to a provided [alloc::vec::Vec]
-    #[cfg(feature = "alloc")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-    pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PusError> {
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        let mut appended_len = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA;
-        if let Some(timestamp) = self.sec_header.timestamp {
-            appended_len += timestamp.len();
-        }
-        if let Some(src_data) = self.source_data {
-            appended_len += src_data.len();
-        };
-        let start_idx = vec.len();
-        let mut ser_len = 0;
-        vec.extend_from_slice(sph_zc.as_bytes());
-        ser_len += sph_zc.as_bytes().len();
-        // The PUS version is hardcoded to PUS C
-        let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        vec.extend_from_slice(sec_header.as_bytes());
-        ser_len += sec_header.as_bytes().len();
-        if let Some(timestamp) = self.sec_header.timestamp {
-            ser_len += timestamp.len();
-            vec.extend_from_slice(timestamp);
-        }
-        if let Some(src_data) = self.source_data {
-            vec.extend_from_slice(src_data);
-            ser_len += src_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            start_idx,
-            ser_len,
-            &vec[start_idx..start_idx + ser_len],
-        )?;
-        vec.extend_from_slice(crc16.to_be_bytes().as_slice());
-        Ok(appended_len)
-    }
-
-    /// Create a [PusTm] instance from a raw slice. On success, it returns a tuple containing
-    /// the instance and the found byte length of the packet. The timestamp length needs to be
-    /// known beforehand.
-    pub fn from_bytes(
-        slice: &'raw_data [u8],
-        timestamp_len: usize,
-    ) -> Result<(Self, usize), PusError> {
-        let raw_data_len = slice.len();
-        if raw_data_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
-            return Err(PusError::RawDataTooShort(raw_data_len));
-        }
-        let mut current_idx = 0;
-        let (sp_header, _) = SpHeader::from_be_bytes(&slice[0..CCSDS_HEADER_LEN])?;
-        current_idx += 6;
-        let total_len = sp_header.total_len();
-        if raw_data_len < total_len || total_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
-            return Err(PusError::RawDataTooShort(raw_data_len));
-        }
-        let sec_header_zc = zc::PusTmSecHeaderWithoutTimestamp::from_bytes(
-            &slice[current_idx..current_idx + PUC_TM_MIN_SEC_HEADER_LEN],
-        )
-        .ok_or(ByteConversionError::ZeroCopyFromError)?;
-        current_idx += PUC_TM_MIN_SEC_HEADER_LEN;
-        let mut timestamp = None;
-        if timestamp_len > 0 {
-            timestamp = Some(&slice[current_idx..current_idx + timestamp_len]);
-        }
-        let zc_sec_header_wrapper = zc::PusTmSecHeader {
-            zc_header: sec_header_zc,
-            timestamp,
-        };
-        current_idx += timestamp_len;
-        let raw_data = &slice[0..total_len];
-        let pus_tm = PusTm {
-            sp_header,
-            sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper).unwrap(),
-            raw_data: Some(&slice[0..total_len]),
-            source_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
-            calc_crc_on_serialization: false,
-            crc16: Some(crc_from_raw_data(raw_data)?),
-        };
-        verify_crc16_from_raw(raw_data, pus_tm.crc16.expect("CRC16 invalid"))?;
-        Ok((pus_tm, total_len))
-    }
-
-    /// If [Self] was constructed [Self::from_bytes], this function will return the slice it was
-    /// constructed from. Otherwise, [None] will be returned.
-    pub fn raw_bytes(&self) -> Option<&'raw_data [u8]> {
-        self.raw_data
-    }
-}
-
-impl PartialEq for PusTm<'_> {
-    fn eq(&self, other: &Self) -> bool {
-        self.sp_header == other.sp_header
-            && self.sec_header == other.sec_header
-            && self.source_data == other.source_data
-    }
-}
-
-//noinspection RsTraitImplementation
-impl CcsdsPacket for PusTm<'_> {
-    ccsds_impl!();
-}
-
-//noinspection RsTraitImplementation
-impl PusPacket for PusTm<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-    });
-
-    fn user_data(&self) -> Option<&[u8]> {
-        self.source_data
-    }
-
-    fn crc16(&self) -> Option<u16> {
-        self.crc16
-    }
-}
-
-//noinspection RsTraitImplementation
-impl GenericPusTmSecondaryHeader for PusTm<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-        fn dest_id(&self) -> u16;
-        fn msg_counter(&self) -> u16;
-        fn sc_time_ref_status(&self) -> u8;
-    });
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::ecss::PusVersion::PusC;
-    use crate::SpHeader;
-
-    fn base_ping_reply_full_ctor(timestamp: &[u8]) -> PusTm {
-        let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, &timestamp);
-        PusTm::new(&mut sph, tm_header, None, true)
-    }
-
-    fn base_hk_reply<'a>(timestamp: &'a [u8], src_data: &'a [u8]) -> PusTm<'a> {
-        let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, &timestamp);
-        PusTm::new(&mut sph, tc_header, Some(src_data), true)
-    }
-
-    fn dummy_timestamp() -> &'static [u8] {
-        return &[0, 1, 2, 3, 4, 5, 6];
-    }
-
-    #[test]
-    fn test_basic() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(&timestamp);
-        verify_ping_reply(&pus_tm, false, 22, dummy_timestamp());
-    }
-
-    #[test]
-    fn test_serialization_no_source_data() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(&timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        verify_raw_ping_reply(&buf);
-    }
-
-    #[test]
-    fn test_serialization_with_source_data() {
-        let src_data = [1, 2, 3];
-        let hk_reply = base_hk_reply(dummy_timestamp(), &src_data);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = hk_reply
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 25);
-        assert_eq!(buf[20], 1);
-        assert_eq!(buf[21], 2);
-        assert_eq!(buf[22], 3);
-    }
-
-    #[test]
-    fn test_setters() {
-        let timestamp = dummy_timestamp();
-        let mut pus_tm = base_ping_reply_full_ctor(&timestamp);
-        pus_tm.set_sc_time_ref_status(0b1010);
-        pus_tm.set_dest_id(0x7fff);
-        pus_tm.set_msg_counter(0x1f1f);
-        assert_eq!(pus_tm.sc_time_ref_status(), 0b1010);
-        assert_eq!(pus_tm.dest_id(), 0x7fff);
-        assert_eq!(pus_tm.msg_counter(), 0x1f1f);
-        assert!(pus_tm.set_apid(0x7ff));
-        assert_eq!(pus_tm.apid(), 0x7ff);
-    }
-
-    #[test]
-    fn test_deserialization_no_source_data() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(&timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        let (tm_deserialized, size) = PusTm::from_bytes(&buf, 7).expect("Deserialization failed");
-        assert_eq!(ser_len, size);
-        verify_ping_reply(&tm_deserialized, false, 22, dummy_timestamp());
-    }
-
-    #[test]
-    fn test_manual_field_update() {
-        let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, dummy_timestamp());
-        let mut tm = PusTm::new(&mut sph, tc_header, None, false);
-        tm.calc_crc_on_serialization = false;
-        assert_eq!(tm.data_len(), 0x00);
-        let mut buf: [u8; 32] = [0; 32];
-        let res = tm.write_to_bytes(&mut buf);
-        assert!(res.is_err());
-        assert!(matches!(res.unwrap_err(), PusError::CrcCalculationMissing));
-        tm.update_ccsds_data_len();
-        assert_eq!(tm.data_len(), 15);
-        tm.calc_own_crc16();
-        let res = tm.write_to_bytes(&mut buf);
-        assert!(res.is_ok());
-        tm.sp_header.data_len = 0;
-        tm.update_packet_fields();
-        assert_eq!(tm.data_len(), 15);
-    }
-
-    #[test]
-    fn test_target_buf_too_small() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(&timestamp);
-        let mut buf: [u8; 16] = [0; 16];
-        let res = pus_tm.write_to_bytes(&mut buf);
-        assert!(res.is_err());
-        let error = res.unwrap_err();
-        assert!(matches!(error, PusError::ByteConversionError { .. }));
-        match error {
-            PusError::ByteConversionError(err) => match err {
-                ByteConversionError::ToSliceTooSmall(size_missmatch) => {
-                    assert_eq!(size_missmatch.expected, 22);
-                    assert_eq!(size_missmatch.found, 16);
-                }
-                _ => panic!("Invalid PUS error {:?}", err),
-            },
-            _ => {
-                panic!("Invalid error {:?}", error);
-            }
-        }
-    }
-
-    #[test]
-    #[cfg(feature = "alloc")]
-    fn test_append_to_vec() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(&timestamp);
-        let mut vec = Vec::new();
-        let res = pus_tm.append_to_vec(&mut vec);
-        assert!(res.is_ok());
-        assert_eq!(res.unwrap(), 22);
-        verify_raw_ping_reply(vec.as_slice());
-    }
-
-    #[test]
-    #[cfg(feature = "alloc")]
-    fn test_append_to_vec_with_src_data() {
-        let src_data = [1, 2, 3];
-        let hk_reply = base_hk_reply(dummy_timestamp(), &src_data);
-        let mut vec = Vec::new();
-        vec.push(4);
-        let res = hk_reply.append_to_vec(&mut vec);
-        assert!(res.is_ok());
-        assert_eq!(res.unwrap(), 25);
-        assert_eq!(vec.len(), 26);
-    }
-
-    fn verify_raw_ping_reply(buf: &[u8]) {
-        // Secondary header is set -> 0b0000_1001 , APID occupies last bit of first byte
-        assert_eq!(buf[0], 0x09);
-        // Rest of APID 0x123
-        assert_eq!(buf[1], 0x23);
-        // Unsegmented is the default, and first byte of 0x234 occupies this byte as well
-        assert_eq!(buf[2], 0xc2);
-        assert_eq!(buf[3], 0x34);
-        assert_eq!(((buf[4] as u16) << 8) | buf[5] as u16, 15);
-        // SC time ref status is 0
-        assert_eq!(buf[6], (PusC as u8) << 4);
-        assert_eq!(buf[7], 17);
-        assert_eq!(buf[8], 2);
-        // MSG counter 0
-        assert_eq!(buf[9], 0x00);
-        assert_eq!(buf[10], 0x00);
-        // Destination ID
-        assert_eq!(buf[11], 0x00);
-        assert_eq!(buf[12], 0x00);
-        // Timestamp
-        assert_eq!(&buf[13..20], dummy_timestamp());
-        let mut digest = CRC_CCITT_FALSE.digest();
-        digest.update(&buf[0..20]);
-        let crc16 = digest.finalize();
-        assert_eq!(((crc16 >> 8) & 0xff) as u8, buf[20]);
-        assert_eq!((crc16 & 0xff) as u8, buf[21]);
-    }
-
-    fn verify_ping_reply(
-        tm: &PusTm,
-        has_user_data: bool,
-        exp_full_len: usize,
-        exp_timestamp: &[u8],
-    ) {
-        assert!(tm.is_tm());
-        assert_eq!(PusPacket::service(tm), 17);
-        assert_eq!(PusPacket::subservice(tm), 2);
-        assert!(tm.sec_header_flag());
-        assert_eq!(tm.len_packed(), exp_full_len);
-        assert_eq!(tm.timestamp().unwrap(), exp_timestamp);
-        if has_user_data {
-            assert!(!tm.user_data().is_none());
-        }
-        assert_eq!(PusPacket::pus_version(tm), PusC);
-        assert_eq!(tm.apid(), 0x123);
-        assert_eq!(tm.seq_count(), 0x234);
-        assert_eq!(tm.data_len(), exp_full_len as u16 - 7);
-        assert_eq!(tm.dest_id(), 0x0000);
-        assert_eq!(tm.msg_counter(), 0x0000);
-        assert_eq!(tm.sc_time_ref_status(), 0b0000);
-    }
-
-    #[test]
-    fn partial_eq_pus_tm() {
-        let timestamp = dummy_timestamp();
-        let pus_tm_1 = base_ping_reply_full_ctor(timestamp);
-        let pus_tm_2 = base_ping_reply_full_ctor(timestamp);
-        assert_eq!(pus_tm_1, pus_tm_2);
-    }
-
-    #[test]
-    fn partial_eq_serialized_vs_derialized() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(timestamp);
-        let mut buf = [0; 32];
-        pus_tm.write_to_bytes(&mut buf).unwrap();
-        assert_eq!(pus_tm, PusTm::from_bytes(&buf, timestamp.len()).unwrap().0);
-    }
-}

src/util.rs

@@ -0,0 +1,734 @@
+use crate::ByteConversionError;
+use core::fmt::{Debug, Display, Formatter};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub trait ToBeBytes {
+    type ByteArray: AsRef<[u8]>;
+    /// Length when written to big endian bytes.
+    fn written_len(&self) -> usize;
+    fn to_be_bytes(&self) -> Self::ByteArray;
+}
+
+impl ToBeBytes for () {
+    type ByteArray = [u8; 0];
+
+    #[inline]
+    fn written_len(&self) -> usize {
+        0
+    }
+
+    #[inline]
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        []
+    }
+}
+
+impl ToBeBytes for u8 {
+    type ByteArray = [u8; 1];
+
+    #[inline]
+    fn written_len(&self) -> usize {
+        1
+    }
+
+    #[inline]
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u8::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u16 {
+    type ByteArray = [u8; 2];
+
+    #[inline]
+    fn written_len(&self) -> usize {
+        2
+    }
+
+    #[inline]
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u16::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u32 {
+    type ByteArray = [u8; 4];
+
+    #[inline]
+    fn written_len(&self) -> usize {
+        4
+    }
+
+    #[inline]
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u32::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u64 {
+    type ByteArray = [u8; 8];
+
+    #[inline]
+    fn written_len(&self) -> usize {
+        8
+    }
+
+    #[inline]
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u64::to_be_bytes(*self)
+    }
+}
+
+pub trait UnsignedEnum {
+    /// Size of the unsigned enumeration in bytes.
+    fn size(&self) -> usize;
+    /// Write the unsigned enumeration to a raw buffer. Returns the written size on success.
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+
+    fn value(&self) -> u64;
+
+    #[cfg(feature = "alloc")]
+    fn to_vec(&self) -> alloc::vec::Vec<u8> {
+        let mut buf = alloc::vec![0; self.size()];
+        self.write_to_be_bytes(&mut buf).unwrap();
+        buf
+    }
+}
+
+pub trait UnsignedEnumExt: UnsignedEnum + Debug + Copy + Clone + PartialEq + Eq {}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum UnsignedByteFieldError {
+    /// Value is too large for specified width of byte field.
+    ValueTooLargeForWidth {
+        width: usize,
+        value: u64,
+    },
+    /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
+    /// applicable, for example for conversions.
+    InvalidWidth {
+        found: usize,
+        expected: Option<usize>,
+    },
+    ByteConversionError(ByteConversionError),
+}
+
+impl From<ByteConversionError> for UnsignedByteFieldError {
+    #[inline]
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl Display for UnsignedByteFieldError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::ByteConversionError(e) => {
+                write!(f, "low level byte conversion error: {e}")
+            }
+            Self::InvalidWidth { found, .. } => {
+                write!(f, "invalid width {found}, only 1, 2, 4 and 8 are allowed.")
+            }
+            Self::ValueTooLargeForWidth { width, value } => {
+                write!(f, "value {value} too large for width {width}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for UnsignedByteFieldError {}
+
+/// Type erased variant.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct UnsignedByteField {
+    width: usize,
+    value: u64,
+}
+
+impl UnsignedByteField {
+    #[inline]
+    pub const fn new(width: usize, value: u64) -> Self {
+        Self { width, value }
+    }
+
+    #[inline]
+    pub const fn value_const(&self) -> u64 {
+        self.value
+    }
+
+    #[inline]
+    pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, UnsignedByteFieldError> {
+        if width > buf.len() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                expected: width,
+                found: buf.len(),
+            }
+            .into());
+        }
+        match width {
+            0 => Ok(Self::new(width, 0)),
+            1 => Ok(Self::new(width, buf[0] as u64)),
+            2 => Ok(Self::new(
+                width,
+                u16::from_be_bytes(buf[0..2].try_into().unwrap()) as u64,
+            )),
+            4 => Ok(Self::new(
+                width,
+                u32::from_be_bytes(buf[0..4].try_into().unwrap()) as u64,
+            )),
+            8 => Ok(Self::new(
+                width,
+                u64::from_be_bytes(buf[0..8].try_into().unwrap()),
+            )),
+            _ => Err(UnsignedByteFieldError::InvalidWidth {
+                found: width,
+                expected: None,
+            }),
+        }
+    }
+}
+
+impl UnsignedEnum for UnsignedByteField {
+    #[inline]
+    fn size(&self) -> usize {
+        self.width
+    }
+
+    #[inline]
+    fn value(&self) -> u64 {
+        self.value_const()
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.size() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                expected: self.size(),
+                found: buf.len(),
+            });
+        }
+        match self.size() {
+            0 => Ok(0),
+            1 => {
+                let u8 = UnsignedByteFieldU8::try_from(*self).unwrap();
+                u8.write_to_be_bytes(buf)
+            }
+            2 => {
+                let u16 = UnsignedByteFieldU16::try_from(*self).unwrap();
+                u16.write_to_be_bytes(buf)
+            }
+            4 => {
+                let u32 = UnsignedByteFieldU32::try_from(*self).unwrap();
+                u32.write_to_be_bytes(buf)
+            }
+            8 => {
+                let u64 = UnsignedByteFieldU64::try_from(*self).unwrap();
+                u64.write_to_be_bytes(buf)
+            }
+            _ => {
+                // The API does not allow this.
+                panic!("unexpected written length");
+            }
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct GenericUnsignedByteField<TYPE: Copy + Into<u64>> {
+    value: TYPE,
+}
+
+impl<TYPE: Copy + Into<u64>> GenericUnsignedByteField<TYPE> {
+    pub const fn new(val: TYPE) -> Self {
+        Self { value: val }
+    }
+
+    pub const fn value_typed(&self) -> TYPE {
+        self.value
+    }
+}
+
+impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericUnsignedByteField<TYPE> {
+    #[inline]
+    fn size(&self) -> usize {
+        self.value.written_len()
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.size() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.size(),
+            });
+        }
+        buf[..self.size()].copy_from_slice(self.value.to_be_bytes().as_ref());
+        Ok(self.value.written_len())
+    }
+
+    #[inline]
+    fn value(&self) -> u64 {
+        self.value_typed().into()
+    }
+}
+
+pub type UnsignedByteFieldEmpty = GenericUnsignedByteField<()>;
+pub type UnsignedByteFieldU8 = GenericUnsignedByteField<u8>;
+pub type UnsignedByteFieldU16 = GenericUnsignedByteField<u16>;
+pub type UnsignedByteFieldU32 = GenericUnsignedByteField<u32>;
+pub type UnsignedByteFieldU64 = GenericUnsignedByteField<u64>;
+
+pub type UbfU8 = UnsignedByteFieldU8;
+pub type UbfU16 = UnsignedByteFieldU16;
+pub type UbfU32 = UnsignedByteFieldU32;
+pub type UbfU64 = UnsignedByteFieldU64;
+
+impl From<UnsignedByteFieldU8> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU8) -> Self {
+        Self::new(1, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU8 {
+    type Error = UnsignedByteFieldError;
+
+    #[inline]
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 1 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(1),
+            });
+        }
+        Ok(Self::new(value.value as u8))
+    }
+}
+
+impl From<UnsignedByteFieldU16> for UnsignedByteField {
+    #[inline]
+    fn from(value: UnsignedByteFieldU16) -> Self {
+        Self::new(2, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU16 {
+    type Error = UnsignedByteFieldError;
+
+    #[inline]
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 2 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(2),
+            });
+        }
+        Ok(Self::new(value.value as u16))
+    }
+}
+
+impl From<UnsignedByteFieldU32> for UnsignedByteField {
+    #[inline]
+    fn from(value: UnsignedByteFieldU32) -> Self {
+        Self::new(4, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU32 {
+    type Error = UnsignedByteFieldError;
+
+    #[inline]
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 4 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(4),
+            });
+        }
+        Ok(Self::new(value.value as u32))
+    }
+}
+
+impl From<UnsignedByteFieldU64> for UnsignedByteField {
+    #[inline]
+    fn from(value: UnsignedByteFieldU64) -> Self {
+        Self::new(8, value.value)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU64 {
+    type Error = UnsignedByteFieldError;
+
+    #[inline]
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 8 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(8),
+            });
+        }
+        Ok(Self::new(value.value))
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::util::{
+        UnsignedByteField, UnsignedByteFieldError, UnsignedByteFieldU16, UnsignedByteFieldU32,
+        UnsignedByteFieldU64, UnsignedByteFieldU8, UnsignedEnum,
+    };
+    use crate::ByteConversionError;
+    use std::format;
+
+    #[test]
+    fn test_simple_u8() {
+        let u8 = UnsignedByteFieldU8::new(5);
+        assert_eq!(u8.size(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u8
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 1);
+        assert_eq!(buf[0], 5);
+        for val in buf.iter().skip(1) {
+            assert_eq!(*val, 0);
+        }
+        assert_eq!(u8.value_typed(), 5);
+        assert_eq!(u8.value(), 5);
+    }
+
+    #[test]
+    fn test_simple_u16() {
+        let u16 = UnsignedByteFieldU16::new(3823);
+        assert_eq!(u16.size(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u16
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 2);
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for val in buf.iter().skip(2) {
+            assert_eq!(*val, 0);
+        }
+        assert_eq!(u16.value_typed(), 3823);
+        assert_eq!(u16.value(), 3823);
+    }
+
+    #[test]
+    fn test_simple_u32() {
+        let u32 = UnsignedByteFieldU32::new(80932);
+        assert_eq!(u32.size(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u32
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 4);
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        (4..8).for_each(|i| {
+            assert_eq!(buf[i], 0);
+        });
+        assert_eq!(u32.value_typed(), 80932);
+        assert_eq!(u32.value(), 80932);
+    }
+
+    #[test]
+    fn test_simple_u64() {
+        let u64 = UnsignedByteFieldU64::new(5999999);
+        assert_eq!(u64.size(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u64
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 8);
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+        assert_eq!(u64.value_typed(), 5999999);
+        assert_eq!(u64.value(), 5999999);
+    }
+
+    #[test]
+    fn conversions_u8() {
+        let u8 = UnsignedByteFieldU8::new(5);
+        let u8_type_erased = UnsignedByteField::from(u8);
+        assert_eq!(u8_type_erased.width, 1);
+        assert_eq!(u8_type_erased.value, 5);
+        let u8_conv_back =
+            UnsignedByteFieldU8::try_from(u8_type_erased).expect("conversion failed for u8");
+        assert_eq!(u8, u8_conv_back);
+        assert_eq!(u8_conv_back.value, 5);
+    }
+
+    #[test]
+    fn conversion_u8_fails() {
+        let field = UnsignedByteField::new(2, 60000);
+        let conv_fails = UnsignedByteFieldU8::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 2);
+                assert_eq!(expected, 1);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u16() {
+        let u16 = UnsignedByteFieldU16::new(64444);
+        let u16_type_erased = UnsignedByteField::from(u16);
+        assert_eq!(u16_type_erased.width, 2);
+        assert_eq!(u16_type_erased.value, 64444);
+        let u16_conv_back =
+            UnsignedByteFieldU16::try_from(u16_type_erased).expect("conversion failed for u16");
+        assert_eq!(u16, u16_conv_back);
+        assert_eq!(u16_conv_back.value, 64444);
+    }
+
+    #[test]
+    fn conversion_u16_fails() {
+        let field = UnsignedByteField::new(4, 75000);
+        let conv_fails = UnsignedByteFieldU16::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 4);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u32() {
+        let u32 = UnsignedByteFieldU32::new(75000);
+        let u32_type_erased = UnsignedByteField::from(u32);
+        assert_eq!(u32_type_erased.width, 4);
+        assert_eq!(u32_type_erased.value, 75000);
+        let u32_conv_back =
+            UnsignedByteFieldU32::try_from(u32_type_erased).expect("conversion failed for u32");
+        assert_eq!(u32, u32_conv_back);
+        assert_eq!(u32_conv_back.value, 75000);
+    }
+
+    #[test]
+    fn conversion_u32_fails() {
+        let field = UnsignedByteField::new(8, 75000);
+        let conv_fails = UnsignedByteFieldU32::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 8);
+                assert_eq!(expected, 4);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u64() {
+        let u64 = UnsignedByteFieldU64::new(5999999);
+        let u64_type_erased = UnsignedByteField::from(u64);
+        assert_eq!(u64_type_erased.width, 8);
+        assert_eq!(u64_type_erased.value, 5999999);
+        let u64_conv_back =
+            UnsignedByteFieldU64::try_from(u64_type_erased).expect("conversion failed for u64");
+        assert_eq!(u64, u64_conv_back);
+        assert_eq!(u64_conv_back.value, 5999999);
+    }
+
+    #[test]
+    fn conversion_u64_fails() {
+        let field = UnsignedByteField::new(4, 60000);
+        let conv_fails = UnsignedByteFieldU64::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 4);
+                assert_eq!(expected, 8);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u8_write() {
+        let u8 = UnsignedByteField::new(1, 5);
+        assert_eq!(u8.size(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        u8.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(buf[0], 5);
+        (1..8).for_each(|i| {
+            assert_eq!(buf[i], 0);
+        });
+    }
+
+    #[test]
+    fn type_erased_u16_write() {
+        let u16 = UnsignedByteField::new(2, 3823);
+        assert_eq!(u16.size(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        u16.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for val in buf.iter().skip(2) {
+            assert_eq!(*val, 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u32_write() {
+        let u32 = UnsignedByteField::new(4, 80932);
+        assert_eq!(u32.size(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        u32.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        (4..8).for_each(|i| {
+            assert_eq!(buf[i], 0);
+        });
+    }
+
+    #[test]
+    fn type_erased_u64_write() {
+        let u64 = UnsignedByteField::new(8, 5999999);
+        assert_eq!(u64.size(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        u64.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn type_erased_u8_construction() {
+        let buf: [u8; 2] = [5, 10];
+        let u8 = UnsignedByteField::new_from_be_bytes(1, &buf).expect("construction failed");
+        assert_eq!(u8.width, 1);
+        assert_eq!(u8.value, 5);
+    }
+
+    #[test]
+    fn type_erased_u16_construction() {
+        let buf: [u8; 2] = [0x10, 0x15];
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf).expect("construction failed");
+        assert_eq!(u16.width, 2);
+        assert_eq!(u16.value, 0x1015);
+    }
+
+    #[test]
+    fn type_erased_u32_construction() {
+        let buf: [u8; 4] = [0x01, 0x02, 0x03, 0x04];
+        let u32 = UnsignedByteField::new_from_be_bytes(4, &buf).expect("construction failed");
+        assert_eq!(u32.width, 4);
+        assert_eq!(u32.value, 0x01020304);
+    }
+
+    #[test]
+    fn type_erased_u64_construction() {
+        let buf: [u8; 8] = [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08];
+        let u64 = UnsignedByteField::new_from_be_bytes(8, &buf).expect("construction failed");
+        assert_eq!(u64.width, 8);
+        assert_eq!(u64.value, 0x0102030405060708);
+    }
+
+    #[test]
+    fn type_u16_target_buf_too_small() {
+        let u16 = UnsignedByteFieldU16::new(500);
+        let mut buf: [u8; 1] = [0; 1];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 1);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("invalid exception")
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u16_target_buf_too_small() {
+        let u16 = UnsignedByteField::new(2, 500);
+        let mut buf: [u8; 1] = [0; 1];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 1);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("invalid exception {}", err)
+            }
+        }
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf);
+        assert!(u16.is_err());
+        let err = u16.unwrap_err();
+        if let UnsignedByteFieldError::ByteConversionError(
+            ByteConversionError::FromSliceTooSmall { found, expected },
+        ) = err
+        {
+            assert_eq!(expected, 2);
+            assert_eq!(found, 1);
+        } else {
+            panic!("unexpected exception {}", err);
+        }
+    }
+
+    #[test]
+    fn type_u32_target_buf_too_small() {
+        let u16 = UnsignedByteFieldU32::new(500);
+        let mut buf: [u8; 3] = [0; 3];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 3);
+                assert_eq!(expected, 4);
+            }
+            _ => {
+                panic!("invalid exception")
+            }
+        }
+    }
+}