Merge pull request 'prepare v0.16.0' (#165) from prep-v0.16.0 into main

Reviewed-on: #165

.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/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - uses: dtolnay/rust-toolchain@stable
-        with:
+      - run: cargo check --release
-          profile: minimal
-          toolchain: stable
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --release
 
-  msrv:
+  test:
-    name: Check with MSRV
+    name: Run Tests
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - uses: dtolnay/rust-toolchain@stable
-        with:
+      - name: Install nextest
-          toolchain: 1.61.0
+        uses: taiki-e/install-action@nextest
-          override: true
+      - run: cargo nextest run --all-features
-          profile: minimal
+      - run: cargo test --doc
-      - uses: actions-rs/cargo@v1
+
-        with:
+  msrv:
-          command: check
+    name: Check MSRV
-          args: --release
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@1.83
+      - 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/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
+          targets: "armv7-unknown-linux-gnueabihf, thumbv7em-none-eabihf"
-          toolchain: stable
+      - run: cargo check --release --target=${{matrix.target}} --no-default-features
-          target: ${{ matrix.target }}
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          use-cross: true
-          command: check
-          args: --release --target=${{ matrix.target }} --no-default-features
 
   fmt:
-    name: Rustfmt
+    name: Check formatting
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - uses: dtolnay/rust-toolchain@stable
-        with:
+      - run: cargo fmt --all -- --check
-          profile: minimal
-          toolchain: stable
-          override: true
-      - run: rustup component add rustfmt
-      - uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: --all -- --check
 
-  check-doc:
+  docs:
     name: Check Documentation Build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - uses: dtolnay/rust-toolchain@nightly
-        with:
+      - run: RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features
-          toolchain: nightly
-          override: true
-          profile: minimal
-      - uses: actions-rs/cargo@v1
-        with:
-          command: doc
-          args: --all-features
 
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
-      - uses: actions-rs/toolchain@v1
+      - uses: dtolnay/rust-toolchain@stable
-        with:
+      - run: cargo clippy -- -D warnings
-          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

CHANGELOG.md

@@ -8,6 +8,236 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.16.0] 2025-09-24
+
+- Bump Rust MSRV to v1.83
+
+## Changed
+
+- `PusTcCreator` has its own `service`, `subservice` and `apid` methods and does not require trait
+  imports anymore.
+- CFDP NAK PDU `SegmentRequestIter` is not generic over the file size anymore. Instead, the
+  iterator returns pairs of `u64` for both large and normal file size.
+- `PusVersion::VersionNotSupported` contains raw version number instead of `PusVersion` enum now
+  to make it more flexible.
+- `pus_version` API now returns a `Result<PusVersion, u8>` instead of a `PusVersion` to allow
+  modelling invalid version numbers properly.
+- Renamed `CcsdsPacket::total_len` to `CcsdsPacket::packet_len`
+- Renamed `SequenceCountProvider` to `SequenceCounter`
+- Renamed `SeqCountProviderSimple` to `SequenceCounterSimple`
+- Renamed `CcsdsSimpleSeqCountProvider` to `SequenceCounterCcsdsSimple`
+- Renamed `SeqCountProviderSync` to `SequenceCounterSync`
+- Renamed `PusPacket::opt_crc16` to `PusPacket::checksum`
+- Renamed `PacketSequenceCtrl` to `PacketSequenceControl`
+- ECSS checksum generation is now optional as specified in the standard. Added `has_checksum`
+  parameters for ECSS TM/TC creators and readers to reflect this.
+- APID is represented by `arbitrary-int::u11` while the sequence count is represented by
+  `arbitrary-int::u14`. A lot of corresponding checks were removed because the type now ensure
+  value validity.
+- ACK field changed from `u8` to `AckFlags` structure.
+- PUS version raw representation is `u4` now.
+- SC time reference status representation is `u4` now.
+- Renamed `ptype` to `packet_type`
+- Renamed `PduHeader::new_no_file_data` to `PduHeader::new_for_file_directive`
+- Renamd `FinishedPduCreator::new_generic` to `new` and `new_default` to `new_no_error`
+
+## Removed
+
+- `PusVersion::Invalid`, which will be modelled with `Result<PusVersion, u8>` now.
+
+## Added
+
+- `cfdp::pdu::ack::InvalidAckedDirectiveCodeError` which is returned by the `AckPdu` constructor.
+- `cfdp::pdu::nak::NakPduCreatorWithReservedSegReqsBuf` constructor which exposes the segment
+  request buffer mutably to avoid the need for a separate segment request buffer.
+- `SpHeader::packet_len` direct method.
+- `AckFlags` which is implemented with `bitbybit::bitfield`
+- `ApidOutOfRangeError` and `SequenceCountOutOfRangeError`
+- Added PUS A legacy support for telecommands inside the `ecss.tc_pus_a` module
+- Added `SequenceCounter::increment_mut` and `SequenceCounter::get_and_increment_mut`
+- Implemented `SequenceCounter` for `Atomic` unsigned types and references of them
+- `PusPacket::has_checksum` and `WritablePusPacket::has_checksum`
+- PUS TC builder API, either via `PusTcBuilder::new`, or `PusTcCreator::builder`
+
+# [v0.15.0] 2025-07-18
+
+## Added
+
+- `PusTcCreatorWithReservedAppData` and `PusTmCreatorWithReservedSourceData` constructor variants
+  which allow writing source/app data into the serialization buffer directly without
+  requiring an extra buffer.
+
+# [v0.14.0] 2025-05-10
+
+## Changed
+
+- Moved CRC constants/implementations to dedicated `crc` module.
+- `crc::CRC_CCITT_FALSE_NO_TABLE` and `crc::CRC_CCITT_FALSE_BIG_TABLE` variants.
+- Renamed `PusPacket::crc16` to `PusPacket::opt_crc16`.
+
+## Added
+
+- `WritablePusPacket::write_to_bytes_crc_no_table` and `WritablePusPacket::write_to_bytes_no_crc`
+  variants.
+- `PusTmReader::new_crc_no_table` and `PusTcReader::new_crc_no_table` variants.
+- `crc16` methods for PUS TM and PUS TC reader.
+- PUS TM and PUS TC reader now return the reader instance directly instead of a tuple of the reader
+  and the read size. The instance `total_len` method can be used to retrieve the read lenght.
+
+# [v0.13.1] 2025-03-21
+
+- Bugfix due to operator precendence for `PusTcSecondaryHeader::pus_version`,
+  `PusTcSecondaryHeaderWithoutTimestamp::pus_version`, `CdsTime::from_bytes_with_u16_days` and
+  `CdsTime::from_bytes_with_u24_days`
+
+# [v0.13.0] 2024-11-08
+
+- Bumped MSRV to 1.81.0
+- Bump `zerocopy` to v0.8.0
+- Bump `thiserror` to v2.0.0
+
+## Changed
+
+- Migrated all Error implementations to thiserror, improved some naming and error handling in
+  general
+
+# [v0.12.0] 2024-09-10
+
+- Bumped MSRV to 1.70.0
+
+## Added
+
+- Added new `cfdp::tlv::TlvOwned` type which erases the lifetime and is clonable.
+- Dedicated `cfdp::tlv::TlvLvDataTooLarge` error struct for APIs where this is the only possible
+  API error.
+- Added File Data PDU API which expects the expected file data size and then exposes the unwritten
+  file data field as a mutable slice. This allows to read data from the virtual file system
+  API to the file data buffer without an intermediate buffer.
+- Generic `EofPdu::new` constructor.
+- Added generic sequence counter module.
+- Added `MsgToUserTlv::to_tlv` converter which reduced the type and converts
+  it to a generic `Tlv`.
+- Implemented `From<MsgToUserTlv> for Tlv` converter trait.
+- Added CFDP maximum file segment length calculator method `calculate_max_file_seg_len_for_max_packet_len_and_pdu_header`
+
+## Added and Changed
+
+- Added new `ReadableTlv` to avoid some boilerplate code and have a common abstraction implemented
+  for both `Tlv` and `TlvOwned` to read the raw TLV data field and its length.
+- Replaced `cfdp::tlv::TlvLvError` by `cfdp::tlv::TlvLvDataTooLarge` where applicable.
+
+## Fixed
+
+- Fixed an error in the EOF writer which wrote the fault location to the wrong buffer position.
+- cfdp `ConditionCode::CheckLimitReached` previous had the wrong numerical value of `0b1001` (9)
+  and now has the correct value of `0b1010` (10).
+
+## Changed
+
+- Minor documentation build updates.
+- Increased delegate version range to v0.13
+
+# [v0.11.2] 2024-05-19
+
+- Bumped MSRV to 1.68.2
+
+## 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
@@ -413,3 +643,11 @@ The timestamp of `PusTm` is now optional. See Added and Changed section for deta
 
 Initial release with CCSDS Space Packet Primary Header implementation and basic PUS TC and TM
 implementations.
+
+[unreleased]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.16.0...HEAD
+[v0.16.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.15.0...v0.16.0
+[v0.15.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.14.0...v0.15.0
+[v0.14.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.13.1...v0.14.0
+[v0.13.1]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.13.0...v0.13.1
+[v0.13.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.12.0...v0.13.0
+[v0.12.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.11.2...v0.12.0

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "spacepackets"
-version = "0.11.0-rc.0"
+version = "0.16.0"
 edition = "2021"
-rust-version = "1.61"
+rust-version = "1.83"
 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"
@@ -14,43 +14,33 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 
 [dependencies]
 crc = "3"
-delegate = ">=0.8, <0.11"
+delegate = ">=0.8, <=0.13"
+paste = "1"
+zerocopy = { version = "0.8", features = ["derive"] }
+thiserror = { version = "2", default-features = false }
+num_enum = { version = ">0.5, <=0.7", default-features = false }
+num-traits = { version = "0.2", default-features = false }
+serde = { version = "1", optional = true, default-features = false, features = ["derive"] }
+arbitrary-int = { version = "2" }
+portable-atomic = "1"
+bitbybit = "1.4"
 
-[dependencies.zerocopy]
+time = { version = "0.3", default-features = false, optional = true }
-version = "0.7"
+chrono = { version = "0.4", default-features = false, optional = true }
-features = ["derive"]
+defmt = { version = "1", default-features = false, optional = true }
-
-[dependencies.thiserror]
-version = "1"
-optional = true
-
-[dependencies.num_enum]
-version = ">0.5, <=0.7"
-default-features = false
-
-[dependencies.serde]
-version = "1"
-optional = true
-default-features = false
-features = ["derive"]
-
-[dependencies.chrono]
-version = "0.4"
-default-features = false
-
-[dependencies.num-traits]
-version = "0.2"
-default-features = false
-
-[dev-dependencies.postcard]
-version = "1"
 
 [features]
 default = ["std"]
-std = ["chrono/std", "chrono/clock", "alloc", "thiserror"]
+std = ["alloc", "chrono/std", "chrono/clock", "thiserror/std"]
-serde = ["dep:serde", "chrono/serde"]
+defmt = ["dep:defmt", "arbitrary-int/defmt"]
-alloc = ["postcard/alloc", "chrono/alloc"]
+serde = ["dep:serde", "chrono?/serde", "arbitrary-int/serde"]
+alloc = ["chrono?/alloc", "defmt?/alloc", "serde?/alloc"]
+timelib = ["dep:time"]
+
+[dev-dependencies]
+postcard = { version = "1", features = ["alloc"] }
+chrono = "0.4"
 
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "doc_cfg", "--generate-link-to-definition"]
+rustdoc-args = ["--generate-link-to-definition"]

FUNDING.yml

@@ -0,0 +1 @@
+github: robamu

README.md

@@ -1,7 +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)
+[![matrix chat](https://img.shields.io/matrix/sat-rs%3Amatrix.org)](https://matrix.to/#/#sat-rs:matrix.org)
 
 ECSS and CCSDS Spacepackets
 ======
@@ -29,10 +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.
@@ -43,6 +39,10 @@ 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
 
@@ -51,13 +51,21 @@ usage examples.
 
 # Coverage
 
-Coverage was generated using [`grcov`](https://github.com/mozilla/grcov). If you have not done so
+Coverage can be generated using [`llvm-cov`](https://github.com/taiki-e/cargo-llvm-cov). If you have not done so
-already, install the `llvm-tools-preview`:
+already, install the tool:
 
 ```sh
-rustup component add llvm-tools-preview
+cargo +stable install cargo-llvm-cov --locked
-cargo install grcov --locked
 ```
 
-After that, you can simply run `coverage.py` to test the project with coverage. You can optionally
+After this, you can run `cargo llvm-cov nextest` to run all the tests and display coverage.
-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

@@ -15,7 +15,10 @@ RUN rustup install nightly && \
     rustup target add thumbv7em-none-eabihf armv7-unknown-linux-gnueabihf && \
     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

automation/Jenkinsfile

@@ -21,7 +21,9 @@ pipeline {
     }
     stage('Docs') {
         steps {
-          sh 'cargo +nightly doc --all-features'
+          sh """
+            RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features
+          """
         }
     }
     stage('Rustfmt') {
@@ -31,7 +33,8 @@ pipeline {
     }
     stage('Test') {
       steps {
-        sh 'cargo test --all-features'
+        sh 'cargo nextest r --all-features'
+        sh 'cargo test --doc'
       }
     }
     stage('Check with all features') {

coverage.py

@@ -1,54 +0,0 @@
-#!/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()

justfile

@@ -0,0 +1,31 @@
+all: check build test clippy fmt docs coverage
+
+clippy:
+  cargo clippy -- -D warnings
+
+fmt:
+  cargo fmt --all -- --check
+
+check:
+  cargo check --all-features
+
+test:
+  cargo nextest r --all-features
+  cargo test --doc
+
+build:
+  cargo build --all-features
+
+docs:
+  export RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options"
+  cargo +nightly doc --all-features
+
+docs-html:
+  export RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options"
+  cargo +nightly doc --all-features --open
+
+coverage:
+  cargo llvm-cov nextest
+
+coverage-html:
+  cargo llvm-cov nextest --html --open

release-checklist.md

@@ -4,11 +4,14 @@ Checklist for new releases
 # Pre-Release
 
 1. Make sure any new modules are documented sufficiently enough and check docs with
-   `cargo +nightly doc --all-features --config 'rustdocflags=["--cfg", "doc_cfg"]' --open`.
+   `RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features --open`
+   or `cargo +nightly doc --all-features --config 'build.rustdocflags=["--cfg", "docsrs" --generate-link-to-definition"]' --open`
+   (was problematic on more recent nightly versions).
 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.

src/cfdp/lv.rs

@@ -1,5 +1,4 @@
 //! 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")]
@@ -7,6 +6,8 @@ use serde::{Deserialize, Serialize};
 #[cfg(feature = "std")]
 use std::string::String;
 
+use super::TlvLvDataTooLargeError;
+
 pub const MIN_LV_LEN: usize = 1;
 
 /// Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
@@ -20,6 +21,7 @@ pub const MIN_LV_LEN: usize = 1;
 ///    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
@@ -61,9 +63,12 @@ pub(crate) fn generic_len_check_deserialization(
 }
 
 impl<'data> Lv<'data> {
-    pub fn new(data: &[u8]) -> Result<Lv, TlvLvError> {
+    pub const MIN_LEN: usize = MIN_LV_LEN;
+
+    #[inline]
+    pub fn new(data: &[u8]) -> Result<Lv<'_>, TlvLvDataTooLargeError> {
         if data.len() > u8::MAX as usize {
-            return Err(TlvLvError::DataTooLarge(data.len()));
+            return Err(TlvLvDataTooLargeError(data.len()));
         }
         Ok(Lv {
             data,
@@ -72,6 +77,7 @@ impl<'data> Lv<'data> {
     }
 
     /// Creates a LV with an empty value field.
+    #[inline]
     pub fn new_empty() -> Lv<'data> {
         Lv {
             data: &[],
@@ -81,45 +87,52 @@ impl<'data> Lv<'data> {
 
     /// Helper function to build a string LV. This is especially useful for the file or directory
     /// path LVs
-    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvError> {
+    #[inline]
+    pub fn new_from_str(str_slice: &str) -> Result<Lv<'_>, TlvLvDataTooLargeError> {
         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")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    #[inline]
-    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvError> {
+    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvDataTooLargeError> {
         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;
@@ -135,6 +148,7 @@ impl<'data> Lv<'data> {
     }
 
     /// 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)
@@ -151,6 +165,7 @@ impl<'data> Lv<'data> {
         MIN_LV_LEN + self.data.len()
     }
 
+    #[inline]
     pub(crate) fn from_be_bytes_no_len_check(
         buf: &'data [u8],
     ) -> Result<Lv<'data>, ByteConversionError> {
@@ -165,10 +180,10 @@ impl<'data> Lv<'data> {
 
 #[cfg(test)]
 pub mod tests {
-    use super::*;
     use alloc::string::ToString;
 
-    use crate::cfdp::TlvLvError;
+    use super::*;
+
     use crate::ByteConversionError;
     use std::string::String;
 
@@ -259,15 +274,11 @@ pub mod tests {
         let lv = Lv::new(&data_big);
         assert!(lv.is_err());
         let error = lv.unwrap_err();
-        if let TlvLvError::DataTooLarge(size) = error {
+        assert_eq!(error.0, u8::MAX as usize + 1);
-            assert_eq!(size, u8::MAX as usize + 1);
+        assert_eq!(
-            assert_eq!(
+            error.to_string(),
-                error.to_string(),
+            "data with size 256 larger than allowed 255 bytes"
-                "data with size 256 larger than allowed 255 bytes"
+        );
-            );
-        } else {
-            panic!("invalid exception {:?}", error)
-        }
     }
 
     #[test]

src/cfdp/mod.rs

@@ -1,11 +1,8 @@
 //! 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;
@@ -16,32 +13,40 @@ 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)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum PduType {
     FileDirective = 0,
     FileData = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum Direction {
     TowardsReceiver = 0,
     TowardsSender = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum TransmissionMode {
     Acknowledged = 0,
     Unacknowledged = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum CrcFlag {
     NoCrc = 0,
@@ -67,8 +72,10 @@ impl From<CrcFlag> for bool {
 }
 
 /// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum SegmentMetadataFlag {
     NotPresent = 0,
@@ -76,16 +83,20 @@ pub enum SegmentMetadataFlag {
 }
 
 /// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum SegmentationControl {
     NoRecordBoundaryPreservation = 0,
     WithRecordBoundaryPreservation = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u3, exhaustive = false)]
 #[repr(u8)]
 pub enum FaultHandlerCode {
     NoticeOfCancellation = 0b0001,
@@ -94,8 +105,10 @@ pub enum FaultHandlerCode {
     AbandonTransaction = 0b0100,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u4, exhaustive = false)]
 #[repr(u8)]
 pub enum ConditionCode {
     /// This is not an error condition for which a faulty handler override can be specified
@@ -108,7 +121,7 @@ pub enum ConditionCode {
     FileSizeError = 0b0110,
     NakLimitReached = 0b0111,
     InactivityDetected = 0b1000,
-    CheckLimitReached = 0b1001,
+    CheckLimitReached = 0b1010,
     UnsupportedChecksumType = 0b1011,
     /// Not an actual fault condition for which fault handler overrides can be specified
     SuspendRequestReceived = 0b1110,
@@ -116,8 +129,10 @@ pub enum ConditionCode {
     CancelRequestReceived = 0b1111,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum LargeFileFlag {
     /// 32 bit maximum file size and FSS size
@@ -127,8 +142,10 @@ pub enum LargeFileFlag {
 }
 
 /// 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)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u2, exhaustive = true)]
 #[repr(u8)]
 pub enum TransactionStatus {
     /// Transaction is not currently active and the CFDP implementation does not retain a
@@ -146,6 +163,7 @@ pub enum TransactionStatus {
 /// [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
@@ -165,75 +183,43 @@ impl Default for ChecksumType {
 
 pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[error("data with size {0} larger than allowed {max} bytes", max = u8::MAX)]
+pub struct TlvLvDataTooLargeError(pub usize);
+
+/// First value: Found value. Second value: Expected value if there is one.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[error("invalid TLV type field, found {found}, expected {expected:?}")]
+pub struct InvalidTlvTypeFieldError {
+    found: u8,
+    expected: Option<u8>,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum TlvLvError {
-    DataTooLarge(usize),
+    #[error("{0}")]
-    ByteConversion(ByteConversionError),
+    DataTooLarge(#[from] TlvLvDataTooLargeError),
-    /// First value: Found value. Second value: Expected value if there is one.
+    #[error("byte conversion error: {0}")]
-    InvalidTlvTypeField {
+    ByteConversion(#[from] ByteConversionError),
-        found: u8,
+    #[error("{0}")]
-        expected: Option<u8>,
+    InvalidTlvTypeField(#[from] InvalidTlvTypeFieldError),
-    },
+    #[error("invalid value length {0}")]
-    /// 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.
+    #[error("second name missing for filestore request or response")]
     SecondNameMissing,
     /// Invalid action code for filestore requests or responses.
+    #[error("invalid action code {0}")]
     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::*;

src/cfdp/pdu/ack.rs

@@ -10,11 +10,16 @@ use super::{
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, thiserror::Error)]
+#[error("invalid directive code of acknowledged PDU")]
+pub struct InvalidAckedDirectiveCodeError(pub FileDirectiveType);
+
 /// 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,
@@ -28,16 +33,13 @@ impl AckPdu {
         directive_code_of_acked_pdu: FileDirectiveType,
         condition_code: ConditionCode,
         transaction_status: TransactionStatus,
-    ) -> Result<Self, PduError> {
+    ) -> Result<Self, InvalidAckedDirectiveCodeError> {
         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 {
+            return Err(InvalidAckedDirectiveCodeError(directive_code_of_acked_pdu));
-                found: directive_code_of_acked_pdu as u8,
-                expected: None,
-            });
         }
         // Force correct direction flag.
         let mut ack_pdu = Self {
@@ -80,22 +82,27 @@ impl AckPdu {
         .unwrap()
     }
 
+    #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
     }
 
+    #[inline]
     pub fn directive_code_of_acked_pdu(&self) -> FileDirectiveType {
         self.directive_code_of_acked_pdu
     }
 
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    #[inline]
     pub fn transaction_status(&self) -> TransactionStatus {
         self.transaction_status
     }
 
+    #[inline]
     fn calc_pdu_datafield_len(&self) -> usize {
         if self.crc_flag() == CrcFlag::WithCrc {
             return 5;
@@ -139,27 +146,18 @@ impl AckPdu {
         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(
+        // Unwrap okay, validity of acked directive code was checked.
+        Ok(Self::new(
             pdu_header,
             acked_directive_type,
             condition_code,
             transaction_status,
         )
-    }
+        .unwrap())
-}
-
-impl CfdpPdu for AckPdu {
-    fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
     }
 
-    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+    /// Write [Self] to the provided buffer and returns the written size.
-        Some(FileDirectiveType::AckPdu)
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
-    }
-}
-
-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 {
@@ -187,11 +185,33 @@ impl WritablePduPacket for AckPdu {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for AckPdu {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    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> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::cfdp::{
@@ -224,7 +244,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new(
             pdu_header,
             FileDirectiveType::FinishedPdu,
@@ -244,7 +264,7 @@ mod tests {
         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 pdu_header = PduHeader::new_for_file_directive(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);
@@ -266,15 +286,53 @@ mod tests {
         generic_serialization_test(ConditionCode::NoError, TransactionStatus::Active);
     }
 
+    #[test]
+    fn test_serialization_too_small() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
+        let ack_pdu = AckPdu::new(
+            pdu_header,
+            FileDirectiveType::FinishedPdu,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        )
+        .expect("creating ACK PDU failed");
+        if let Err(PduError::ByteConversion(ByteConversionError::ToSliceTooSmall {
+            found,
+            expected,
+        })) = ack_pdu.write_to_bytes(&mut [0; 5])
+        {
+            assert_eq!(found, 5);
+            assert_eq!(expected, ack_pdu.len_written());
+        } else {
+            panic!("serialization should have failed");
+        }
+    }
+
     #[test]
     fn test_serialization_fs_error() {
         generic_serialization_test(ConditionCode::FileSizeError, TransactionStatus::Terminated);
     }
+    #[test]
+    fn test_invalid_directive_code_of_acked_pdu() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
+        assert_eq!(
+            AckPdu::new(
+                pdu_header,
+                FileDirectiveType::MetadataPdu,
+                ConditionCode::NoError,
+                TransactionStatus::Active,
+            )
+            .unwrap_err(),
+            InvalidAckedDirectiveCodeError(FileDirectiveType::MetadataPdu)
+        );
+    }
 
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_finished_pdu(
             pdu_header,
             ConditionCode::NoError,
@@ -289,7 +347,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_finished_pdu(
             pdu_header,
             ConditionCode::NoError,
@@ -306,7 +364,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_eof_pdu(
             pdu_header,
             ConditionCode::NoError,
@@ -323,7 +381,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_eof_pdu(
             pdu_header,
             ConditionCode::NoError,

src/cfdp/pdu/eof.rs

@@ -15,6 +15,7 @@ use super::{CfdpPdu, WritablePduPacket};
 /// 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,
@@ -24,32 +25,52 @@ pub struct EofPdu {
 }
 
 impl EofPdu {
-    pub fn new_no_error(mut pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+    pub fn new(
+        mut pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        file_checksum: u32,
+        file_size: u64,
+        fault_location: Option<EntityIdTlv>,
+    ) -> Self {
         // Force correct direction flag.
         pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
         let mut eof_pdu = Self {
             pdu_header,
-            condition_code: ConditionCode::NoError,
+            condition_code,
             file_checksum,
             file_size,
-            fault_location: None,
+            fault_location,
         };
         eof_pdu.pdu_header.pdu_datafield_len = eof_pdu.calc_pdu_datafield_len() as u16;
         eof_pdu
     }
 
+    pub fn new_no_error(pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+        Self::new(
+            pdu_header,
+            ConditionCode::NoError,
+            file_checksum,
+            file_size,
+            None,
+        )
+    }
+
+    #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
     }
 
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    #[inline]
     pub fn file_checksum(&self) -> u32 {
         self.file_checksum
     }
 
+    #[inline]
     pub fn file_size(&self) -> u64 {
         self.file_size
     }
@@ -112,20 +133,9 @@ impl EofPdu {
             fault_location,
         })
     }
-}
 
-impl CfdpPdu for EofPdu {
+    /// Write [Self] to the provided buffer and returns the written size.
-    fn pdu_header(&self) -> &PduHeader {
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
-        &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 {
@@ -147,7 +157,7 @@ impl WritablePduPacket for EofPdu {
             &mut buf[current_idx..],
         )?;
         if let Some(fault_location) = self.fault_location {
-            current_idx += fault_location.write_to_bytes(buf)?;
+            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);
@@ -155,11 +165,33 @@ impl WritablePduPacket for EofPdu {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for EofPdu {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    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> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -170,13 +202,23 @@ mod tests {
     use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag, PduType, TransmissionMode};
     #[cfg(feature = "serde")]
     use crate::tests::generic_serde_test;
+    use crate::util::{UnsignedByteFieldU16, UnsignedEnum};
 
-    fn verify_state(&eof_pdu: &EofPdu, file_flag: LargeFileFlag) {
+    fn verify_state_no_error_no_crc(eof_pdu: &EofPdu, file_flag: LargeFileFlag) {
+        verify_state(eof_pdu, CrcFlag::NoCrc, file_flag, ConditionCode::NoError);
+    }
+
+    fn verify_state(
+        eof_pdu: &EofPdu,
+        crc_flag: CrcFlag,
+        file_flag: LargeFileFlag,
+        cond_code: ConditionCode,
+    ) {
         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.condition_code(), cond_code);
 
-        assert_eq!(eof_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(eof_pdu.crc_flag(), crc_flag);
         assert_eq!(eof_pdu.file_flag(), file_flag);
         assert_eq!(eof_pdu.pdu_type(), PduType::FileDirective);
         assert_eq!(
@@ -193,16 +235,16 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(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);
+        verify_state_no_error_no_crc(&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 pdu_header = PduHeader::new_for_file_directive(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);
@@ -234,7 +276,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(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();
@@ -249,7 +291,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(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();
@@ -260,7 +302,7 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(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();
@@ -270,7 +312,7 @@ mod tests {
         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 {
+        if let PduError::Checksum(e) = error {
             assert_eq!(e, crc);
         } else {
             panic!("expected crc error");
@@ -280,9 +322,9 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
-        verify_state(&eof_pdu, LargeFileFlag::Large);
+        verify_state_no_error_no_crc(&eof_pdu, LargeFileFlag::Large);
         assert_eq!(eof_pdu.len_written(), pdu_header.header_len() + 2 + 8 + 4);
     }
 
@@ -290,8 +332,52 @@ mod tests {
     #[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 pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         generic_serde_test(eof_pdu);
     }
+
+    fn generic_test_with_fault_location_and_error(crc: CrcFlag) {
+        let pdu_conf = common_pdu_conf(crc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
+        let eof_pdu = EofPdu::new(
+            pdu_header,
+            ConditionCode::FileChecksumFailure,
+            0x01020304,
+            12,
+            Some(EntityIdTlv::new(UnsignedByteFieldU16::new(5).into())),
+        );
+        let mut expected_len = pdu_header.header_len() + 2 + 4 + 4 + 4;
+        if crc == CrcFlag::WithCrc {
+            expected_len += 2;
+        }
+        // Entity ID TLV increaes length by 4.
+        assert_eq!(eof_pdu.len_written(), expected_len);
+        verify_state(
+            &eof_pdu,
+            crc,
+            LargeFileFlag::Normal,
+            ConditionCode::FileChecksumFailure,
+        );
+        let eof_vec = eof_pdu.to_vec().unwrap();
+        let eof_read_back = EofPdu::from_bytes(&eof_vec);
+        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);
+        assert!(eof_read_back.fault_location.is_some());
+        assert_eq!(eof_read_back.fault_location.unwrap().entity_id().value(), 5);
+        assert_eq!(eof_read_back.fault_location.unwrap().entity_id().size(), 2);
+    }
+
+    #[test]
+    fn test_with_fault_location_and_error() {
+        generic_test_with_fault_location_and_error(CrcFlag::NoCrc);
+    }
+
+    #[test]
+    fn test_with_fault_location_and_error_and_crc() {
+        generic_test_with_fault_location_and_error(CrcFlag::WithCrc);
+    }
 }

src/cfdp/pdu/file_data.rs

@@ -10,8 +10,10 @@ use serde::{Deserialize, Serialize};
 
 use super::{CfdpPdu, FileDirectiveType, WritablePduPacket};
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u2, exhaustive = true)]
 #[repr(u8)]
 pub enum RecordContinuationState {
     NoStartNoEnd = 0b00,
@@ -43,24 +45,27 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
         })
     }
 
+    #[inline]
     pub fn record_continuation_state(&self) -> RecordContinuationState {
         self.record_continuation_state
     }
 
+    #[inline]
     pub fn metadata(&self) -> Option<&'seg_meta [u8]> {
         self.metadata
     }
 
-    pub fn written_len(&self) -> usize {
+    #[inline]
+    pub fn len_written(&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() {
+        if buf.len() < self.len_written() {
             return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
-                expected: self.written_len(),
+                expected: self.len_written(),
             });
         }
         buf[0] = ((self.record_continuation_state as u8) << 6)
@@ -68,7 +73,7 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
         if let Some(metadata) = self.metadata {
             buf[1..1 + metadata.len()].copy_from_slice(metadata)
         }
-        Ok(self.written_len())
+        Ok(self.len_written())
     }
 
     pub(crate) fn from_bytes(buf: &'seg_meta [u8]) -> Result<Self, ByteConversionError> {
@@ -92,16 +97,74 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
     }
 }
 
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+struct FdPduBase<'seg_meta> {
+    pdu_header: PduHeader,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+    offset: u64,
+}
+
+impl CfdpPdu for FdPduBase<'_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
+    }
+}
+
+impl FdPduBase<'_> {
+    fn calc_pdu_datafield_len(&self, file_data_len: u64) -> 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().len_written()
+        }
+        len += file_data_len as usize;
+        if self.crc_flag() == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+
+    fn write_common_fields_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        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..],
+        )?;
+        Ok(current_idx)
+    }
+
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+}
+
 /// 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>>,
+    common: FdPduBase<'seg_meta>,
-    offset: u64,
     file_data: &'file_data [u8],
 }
 
@@ -134,42 +197,42 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
             pdu_header.seg_metadata_flag = SegmentMetadataFlag::Present;
         }
         let mut pdu = Self {
-            pdu_header,
+            common: FdPduBase {
-            segment_metadata,
+                pdu_header,
-            offset,
+                segment_metadata,
+                offset,
+            },
             file_data,
         };
-        pdu.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu.common.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>();
+        self.common
-        if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
+            .calc_pdu_datafield_len(self.file_data.len() as u64)
-            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
     }
 
+    #[inline]
+    pub fn segment_metadata(&self) -> Option<&SegmentMetadata<'_>> {
+        self.common.segment_metadata.as_ref()
+    }
+
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        self.common.pdu_header()
+    }
+
+    #[inline]
     pub fn offset(&self) -> u64 {
-        self.offset
+        self.common.offset
     }
 
+    #[inline]
     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)?;
@@ -178,7 +241,7 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
         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();
+            current_idx += segment_metadata.as_ref().unwrap().len_written();
         }
         let (fss, offset) = read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
         current_idx += fss;
@@ -190,25 +253,17 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
             .into());
         }
         Ok(Self {
-            pdu_header,
+            common: FdPduBase {
-            segment_metadata,
+                pdu_header,
-            offset,
+                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> {
+    /// Write [Self] to the provided buffer and returns the written size.
-        None
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
-    }
-}
-
-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(),
@@ -216,19 +271,8 @@ impl WritablePduPacket for FileDataPdu<'_, '_> {
             }
             .into());
         }
-        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+
-        if self.segment_metadata.is_some() {
+        let mut current_idx = self.common.write_common_fields_to_bytes(buf)?;
-            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 {
@@ -237,10 +281,188 @@ impl WritablePduPacket for FileDataPdu<'_, '_> {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    pub fn len_written(&self) -> usize {
-        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+        self.common.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
+impl CfdpPdu for FileDataPdu<'_, '_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        &self.common.pdu_header
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
+    }
+}
+
+impl WritablePduPacket for FileDataPdu<'_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
+/// File Data PDU creator abstraction.
+///
+/// This special creator object allows to read into the file data buffer directly. This avoids
+/// the need of an additional buffer to create a file data PDU. This structure therefore
+/// does not implement the regular [WritablePduPacket] trait.
+///
+/// For more information, refer to CFDP chapter 5.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FileDataPduCreatorWithReservedDatafield<'seg_meta> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    common: FdPduBase<'seg_meta>,
+    file_data_len: u64,
+}
+
+impl<'seg_meta> FileDataPduCreatorWithReservedDatafield<'seg_meta> {
+    pub fn new_with_seg_metadata(
+        pdu_header: PduHeader,
+        segment_metadata: SegmentMetadata<'seg_meta>,
+        offset: u64,
+        file_data_len: u64,
+    ) -> Self {
+        Self::new_generic(pdu_header, Some(segment_metadata), offset, file_data_len)
+    }
+
+    pub fn new_no_seg_metadata(pdu_header: PduHeader, offset: u64, file_data_len: u64) -> Self {
+        Self::new_generic(pdu_header, None, offset, file_data_len)
+    }
+
+    pub fn new_generic(
+        mut pdu_header: PduHeader,
+        segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+        offset: u64,
+        file_data_len: u64,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileData;
+        if segment_metadata.is_some() {
+            pdu_header.seg_metadata_flag = SegmentMetadataFlag::Present;
+        }
+        let mut pdu = Self {
+            common: FdPduBase {
+                pdu_header,
+                segment_metadata,
+                offset,
+            },
+            file_data_len,
+        };
+        pdu.common.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        self.common.calc_pdu_datafield_len(self.file_data_len)
+    }
+
+    pub fn len_written(&self) -> usize {
+        self.common.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    /// This function performs a partial write by writing all data except the file data
+    /// and the CRC.
+    ///
+    /// It returns a [FileDataPduCreatorWithUnwrittenData] which provides a mutable slice to
+    /// the reserved file data field. The user can read file data into this field directly and
+    /// then finish the PDU creation using the [FileDataPduCreatorWithUnwrittenData::finish] call.
+    pub fn write_to_bytes_partially<'buf>(
+        &self,
+        buf: &'buf mut [u8],
+    ) -> Result<FileDataPduCreatorWithUnwrittenData<'buf>, PduError> {
+        if buf.len() < self.len_written() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_written(),
+            }
+            .into());
+        }
+        let mut current_idx = self.common.write_common_fields_to_bytes(buf)?;
+        let file_data_offset = current_idx as u64;
+        current_idx += self.file_data_len as usize;
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx += 2;
+        }
+        Ok(FileDataPduCreatorWithUnwrittenData {
+            write_buf: &mut buf[0..current_idx],
+            file_data_offset,
+            file_data_len: self.file_data_len,
+            needs_crc: self.crc_flag() == CrcFlag::WithCrc,
+        })
+    }
+}
+
+impl CfdpPdu for FileDataPduCreatorWithReservedDatafield<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.common.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
+    }
+}
+
+/// This structure is created with [FileDataPduCreatorWithReservedDatafield::write_to_bytes_partially]
+/// and provides an API to read file data from the virtual filesystem into the file data PDU buffer
+/// directly.
+///
+/// This structure provides a mutable slice to the reserved file data field. The user can read
+/// file data into this field directly and then finish the PDU creation using the
+/// [FileDataPduCreatorWithUnwrittenData::finish] call.
+pub struct FileDataPduCreatorWithUnwrittenData<'buf> {
+    write_buf: &'buf mut [u8],
+    file_data_offset: u64,
+    file_data_len: u64,
+    needs_crc: bool,
+}
+
+impl FileDataPduCreatorWithUnwrittenData<'_> {
+    pub fn file_data_field_mut(&mut self) -> &mut [u8] {
+        &mut self.write_buf[self.file_data_offset as usize
+            ..self.file_data_offset as usize + self.file_data_len as usize]
+    }
+
+    /// This functio needs to be called to add a CRC to the file data PDU where applicable.
+    ///
+    /// It returns the full written size of the PDU.
+    pub fn finish(self) -> usize {
+        if self.needs_crc {
+            add_pdu_crc(
+                self.write_buf,
+                self.file_data_offset as usize + self.file_data_len as usize,
+            );
+        }
+        self.write_buf.len()
+    }
+}
+
+/// This function can be used to calculate the maximum allowed file segment size for
+/// a given maximum packet length and the segment metadata if there is any.
+pub fn calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(
+    pdu_header: &PduHeader,
+    max_packet_len: usize,
+    segment_metadata: Option<&SegmentMetadata>,
+) -> usize {
+    let mut subtract = pdu_header.header_len();
+    if let Some(segment_metadata) = segment_metadata {
+        subtract += 1 + segment_metadata.metadata().unwrap().len();
+    }
+    if pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
+        subtract += 8;
+    } else {
+        subtract += 4;
+    }
+    if pdu_header.common_pdu_conf().crc_flag == CrcFlag::WithCrc {
+        subtract += 2;
+    }
+    max_packet_len.saturating_sub(subtract)
+}
 
 #[cfg(test)]
 mod tests {
@@ -263,7 +485,7 @@ mod tests {
         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
+            fd_pdu.pdu_header().header_len() + core::mem::size_of::<u32>() + 4
         );
 
         assert_eq!(fd_pdu.crc_flag(), CrcFlag::NoCrc);
@@ -290,11 +512,11 @@ mod tests {
         let written = res.unwrap();
         assert_eq!(
             written,
-            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+            fd_pdu.pdu_header().header_len() + core::mem::size_of::<u32>() + 4
         );
-        let mut current_idx = fd_pdu.pdu_header.header_len();
+        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]
+            buf[fd_pdu.pdu_header().header_len()..fd_pdu.pdu_header().header_len() + 4]
                 .try_into()
                 .unwrap(),
         );
@@ -353,7 +575,7 @@ mod tests {
         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 {
+        if let PduError::Checksum(e) = error {
             assert_eq!(e, crc);
         } else {
             panic!("expected crc error");
@@ -380,7 +602,7 @@ mod tests {
         assert_eq!(*fd_pdu.segment_metadata().unwrap(), segment_meta);
         assert_eq!(
             fd_pdu.len_written(),
-            fd_pdu.pdu_header.header_len()
+            fd_pdu.pdu_header().header_len()
                 + 1
                 + seg_metadata.len()
                 + core::mem::size_of::<u32>()
@@ -390,7 +612,7 @@ mod tests {
         fd_pdu
             .write_to_bytes(&mut buf)
             .expect("writing FD PDU failed");
-        let mut current_idx = fd_pdu.pdu_header.header_len();
+        let mut current_idx = fd_pdu.pdu_header().header_len();
         assert_eq!(
             RecordContinuationState::try_from((buf[current_idx] >> 6) & 0b11).unwrap(),
             RecordContinuationState::StartAndEnd
@@ -482,4 +704,142 @@ mod tests {
         let output_converted_back: FileDataPdu = from_bytes(&output).unwrap();
         assert_eq!(output_converted_back, fd_pdu);
     }
+
+    #[test]
+    fn test_fd_pdu_creator_with_reserved_field_no_crc() {
+        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 test_str = "hello world!";
+        let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
+            pdu_header,
+            10,
+            test_str.len() as u64,
+        );
+        let mut write_buf: [u8; 64] = [0; 64];
+        let mut pdu_unwritten = fd_pdu
+            .write_to_bytes_partially(&mut write_buf)
+            .expect("partial write failed");
+        pdu_unwritten
+            .file_data_field_mut()
+            .copy_from_slice(test_str.as_bytes());
+        pdu_unwritten.finish();
+
+        let pdu_reader = FileDataPdu::from_bytes(&write_buf).expect("reading file data PDU failed");
+        assert_eq!(
+            core::str::from_utf8(pdu_reader.file_data()).expect("reading utf8 string failed"),
+            "hello world!"
+        );
+    }
+
+    #[test]
+    fn test_fd_pdu_creator_with_reserved_field_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 test_str = "hello world!";
+        let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
+            pdu_header,
+            10,
+            test_str.len() as u64,
+        );
+        let mut write_buf: [u8; 64] = [0; 64];
+        let mut pdu_unwritten = fd_pdu
+            .write_to_bytes_partially(&mut write_buf)
+            .expect("partial write failed");
+        pdu_unwritten
+            .file_data_field_mut()
+            .copy_from_slice(test_str.as_bytes());
+        pdu_unwritten.finish();
+
+        let pdu_reader = FileDataPdu::from_bytes(&write_buf).expect("reading file data PDU failed");
+        assert_eq!(
+            core::str::from_utf8(pdu_reader.file_data()).expect("reading utf8 string failed"),
+            "hello world!"
+        );
+    }
+
+    #[test]
+    fn test_fd_pdu_creator_with_reserved_field_with_crc_without_finish_fails() {
+        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 test_str = "hello world!";
+        let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
+            pdu_header,
+            10,
+            test_str.len() as u64,
+        );
+        let mut write_buf: [u8; 64] = [0; 64];
+        let mut pdu_unwritten = fd_pdu
+            .write_to_bytes_partially(&mut write_buf)
+            .expect("partial write failed");
+        pdu_unwritten
+            .file_data_field_mut()
+            .copy_from_slice(test_str.as_bytes());
+
+        let pdu_reader_error = FileDataPdu::from_bytes(&write_buf);
+        assert!(pdu_reader_error.is_err());
+        let error = pdu_reader_error.unwrap_err();
+        match error {
+            PduError::Checksum(_) => (),
+            _ => {
+                panic!("unexpected PDU error {}", error)
+            }
+        }
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_0() {
+        let pdu_header = PduHeader::new_for_file_data_default(CommonPduConfig::default(), 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
+            53
+        );
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_1() {
+        let common_conf = CommonPduConfig {
+            crc_flag: CrcFlag::WithCrc,
+            ..Default::default()
+        };
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
+            51
+        );
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_2() {
+        let common_conf = CommonPduConfig {
+            file_flag: LargeFileFlag::Large,
+            ..Default::default()
+        };
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
+            49
+        );
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_saturating_sub() {
+        let common_conf = CommonPduConfig {
+            file_flag: LargeFileFlag::Large,
+            ..Default::default()
+        };
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 15, None),
+            0
+        );
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 14, None),
+            0
+        );
+    }
 }

src/cfdp/pdu/finished.rs

@@ -4,16 +4,18 @@ use crate::cfdp::pdu::{
 use crate::cfdp::tlv::{
     EntityIdTlv, FilestoreResponseTlv, GenericTlv, Tlv, TlvType, TlvTypeField, WritableTlv,
 };
-use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType, TlvLvError};
+use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType};
 use crate::ByteConversionError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
-use super::{CfdpPdu, WritablePduPacket};
+use super::tlv::ReadableTlv;
+use super::{CfdpPdu, InvalidTlvTypeFieldError, 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,
@@ -22,6 +24,7 @@ pub enum DeliveryCode {
 
 #[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,
@@ -34,6 +37,7 @@ pub enum FileStatus {
 ///
 /// 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,
@@ -46,12 +50,12 @@ pub struct FinishedPduCreator<'fs_responses> {
 
 impl<'fs_responses> FinishedPduCreator<'fs_responses> {
     /// Default finished PDU: No error (no fault location field) and no filestore responses.
-    pub fn new_default(
+    pub fn new_no_error(
         pdu_header: PduHeader,
         delivery_code: DeliveryCode,
         file_status: FileStatus,
     ) -> Self {
-        Self::new_generic(
+        Self::new(
             pdu_header,
             ConditionCode::NoError,
             delivery_code,
@@ -68,7 +72,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         file_status: FileStatus,
         fault_location: EntityIdTlv,
     ) -> Self {
-        Self::new_generic(
+        Self::new(
             pdu_header,
             condition_code,
             delivery_code,
@@ -78,7 +82,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         )
     }
 
-    pub fn new_generic(
+    pub fn new(
         mut pdu_header: PduHeader,
         condition_code: ConditionCode,
         delivery_code: DeliveryCode,
@@ -105,23 +109,33 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         finished_pdu
     }
 
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    #[inline]
     pub fn delivery_code(&self) -> DeliveryCode {
         self.delivery_code
     }
 
+    #[inline]
     pub fn file_status(&self) -> FileStatus {
         self.file_status
     }
 
     // If there are no filestore responses, an empty slice will be returned.
+    #[inline]
     pub fn filestore_responses(&self) -> &[FilestoreResponseTlv<'_, '_, '_>] {
         self.fs_responses
     }
 
+    #[inline]
     pub fn fault_location(&self) -> Option<EntityIdTlv> {
         self.fault_location
     }
@@ -139,20 +153,9 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         }
         datafield_len
     }
-}
 
-impl CfdpPdu for FinishedPduCreator<'_> {
+    /// Write [Self] to the provided buffer and returns the written size.
-    fn pdu_header(&self) -> &PduHeader {
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
-        &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 {
@@ -181,11 +184,33 @@ impl WritablePduPacket for FinishedPduCreator<'_> {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for FinishedPduCreator<'_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    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> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 /// 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]
@@ -219,6 +244,7 @@ impl<'buf> Iterator for FilestoreResponseIterator<'buf> {
 
 #[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,
@@ -271,10 +297,12 @@ impl<'buf> FinishedPduReader<'buf> {
         })
     }
 
+    #[inline]
     pub fn fs_responses_raw(&self) -> &[u8] {
         self.fs_responses_raw
     }
 
+    #[inline]
     pub fn fs_responses_iter(&self) -> FilestoreResponseIterator<'_> {
         FilestoreResponseIterator {
             responses_buf: self.fs_responses_raw,
@@ -282,22 +310,31 @@ impl<'buf> FinishedPduReader<'buf> {
         }
     }
 
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    #[inline]
     pub fn delivery_code(&self) -> DeliveryCode {
         self.delivery_code
     }
 
+    #[inline]
     pub fn file_status(&self) -> FileStatus {
         self.file_status
     }
 
+    #[inline]
     pub fn fault_location(&self) -> Option<EntityIdTlv> {
         self.fault_location
     }
 
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
     fn parse_tlv_fields(
         mut current_idx: usize,
         full_len_without_crc: usize,
@@ -327,22 +364,26 @@ impl<'buf> FinishedPduReader<'buf> {
                         // last TLV, everything else would break the whole handling of the packet
                         // TLVs.
                         if current_idx != full_len_without_crc {
-                            return Err(PduError::FormatError);
+                            return Err(PduError::Format);
                         }
                     } else {
-                        return Err(TlvLvError::InvalidTlvTypeField {
+                        return Err(PduError::TlvLv(
-                            found: tlv_type.into(),
+                            InvalidTlvTypeFieldError {
-                            expected: Some(TlvType::FilestoreResponse.into()),
+                                found: tlv_type.into(),
-                        }
+                                expected: Some(TlvType::FilestoreResponse.into()),
-                        .into());
+                            }
+                            .into(),
+                        ));
                     }
                 }
                 TlvTypeField::Custom(raw) => {
-                    return Err(TlvLvError::InvalidTlvTypeField {
+                    return Err(PduError::TlvLv(
-                        found: raw,
+                        InvalidTlvTypeFieldError {
-                        expected: None,
+                            found: raw,
-                    }
+                            expected: None,
-                    .into());
+                        }
+                        .into(),
+                    ));
                 }
             }
         }
@@ -351,10 +392,12 @@ impl<'buf> FinishedPduReader<'buf> {
 }
 
 impl CfdpPdu for FinishedPduReader<'_> {
+    #[inline]
     fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
+        self.pdu_header()
     }
 
+    #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
         Some(FileDirectiveType::FinishedPdu)
     }
@@ -397,8 +440,8 @@ mod tests {
         delivery_code: DeliveryCode,
         file_status: FileStatus,
     ) -> FinishedPduCreator<'static> {
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_conf(crc_flag, fss), 0);
-        FinishedPduCreator::new_default(pdu_header, delivery_code, file_status)
+        FinishedPduCreator::new_no_error(pdu_header, delivery_code, file_status)
     }
 
     #[test]
@@ -559,7 +602,7 @@ mod tests {
         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 {
+        if let PduError::Checksum(e) = error {
             assert_eq!(e, crc);
         } else {
             panic!("expected crc error");
@@ -568,8 +611,10 @@ mod tests {
 
     #[test]
     fn test_with_fault_location() {
-        let pdu_header =
+        let pdu_header = PduHeader::new_for_file_directive(
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+        );
         let finished_pdu = FinishedPduCreator::new_with_error(
             pdu_header,
             ConditionCode::NakLimitReached,
@@ -590,8 +635,10 @@ mod tests {
 
     #[test]
     fn test_deserialization_with_fault_location() {
-        let pdu_header =
+        let pdu_header = PduHeader::new_for_file_directive(
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+            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,
@@ -626,9 +673,11 @@ mod tests {
         .unwrap();
         let fs_responses = &[fs_response_0, fs_response_1];
 
-        let pdu_header =
+        let pdu_header = PduHeader::new_for_file_directive(
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
-        let finished_pdu = FinishedPduCreator::new_generic(
+            0,
+        );
+        let finished_pdu = FinishedPduCreator::new(
             pdu_header,
             ConditionCode::NakLimitReached,
             DeliveryCode::Incomplete,
@@ -661,9 +710,11 @@ mod tests {
         .unwrap();
         let fs_responses = &[fs_response_0, fs_response_1];
 
-        let pdu_header =
+        let pdu_header = PduHeader::new_for_file_directive(
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
-        let finished_pdu = FinishedPduCreator::new_generic(
+            0,
+        );
+        let finished_pdu = FinishedPduCreator::new(
             pdu_header,
             ConditionCode::NakLimitReached,
             DeliveryCode::Incomplete,

src/cfdp/pdu/metadata.rs

@@ -1,3 +1,5 @@
+#[cfg(feature = "alloc")]
+use super::tlv::TlvOwned;
 use crate::cfdp::lv::Lv;
 use crate::cfdp::pdu::{
     add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
@@ -11,10 +13,12 @@ use alloc::vec::Vec;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+use super::tlv::ReadableTlv;
 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,
@@ -50,6 +54,15 @@ pub fn build_metadata_opts_from_vec(
     build_metadata_opts_from_slice(buf, tlvs.as_slice())
 }
 
+#[cfg(feature = "alloc")]
+pub fn build_metadata_opts_from_owned_slice(tlvs: &[TlvOwned]) -> Vec<u8> {
+    let mut sum_vec = Vec::new();
+    for tlv in tlvs {
+        sum_vec.extend(tlv.to_vec());
+    }
+    sum_vec
+}
+
 /// Metadata PDU creator abstraction.
 ///
 /// This abstraction exposes a specialized API for creating metadata PDUs as specified in
@@ -60,7 +73,7 @@ pub struct MetadataPduCreator<'src_name, 'dest_name, 'opts> {
     metadata_params: MetadataGenericParams,
     src_file_name: Lv<'src_name>,
     dest_file_name: Lv<'dest_name>,
-    options: &'opts [Tlv<'opts>],
+    options: &'opts [u8],
 }
 
 impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'opts> {
@@ -84,7 +97,7 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         metadata_params: MetadataGenericParams,
         src_file_name: Lv<'src_name>,
         dest_file_name: Lv<'dest_name>,
-        options: &'opts [Tlv<'opts>],
+        options: &'opts [u8],
     ) -> Self {
         Self::new(
             pdu_header,
@@ -100,7 +113,7 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         metadata_params: MetadataGenericParams,
         src_file_name: Lv<'src_name>,
         dest_file_name: Lv<'dest_name>,
-        options: &'opts [Tlv<'opts>],
+        options: &'opts [u8],
     ) -> Self {
         pdu_header.pdu_type = PduType::FileDirective;
         pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
@@ -115,22 +128,40 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         pdu
     }
 
+    #[inline]
     pub fn metadata_params(&self) -> &MetadataGenericParams {
         &self.metadata_params
     }
 
+    #[inline]
     pub fn src_file_name(&self) -> Lv<'src_name> {
         self.src_file_name
     }
 
+    #[inline]
     pub fn dest_file_name(&self) -> Lv<'dest_name> {
         self.dest_file_name
     }
 
-    pub fn options(&self) -> &'opts [Tlv<'opts>] {
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    #[inline]
+    pub fn options(&self) -> &'opts [u8] {
         self.options
     }
 
+    /// 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) -> OptionsIter<'_> {
+        OptionsIter {
+            opt_buf: self.options,
+            current_idx: 0,
+        }
+    }
+
     fn calc_pdu_datafield_len(&self) -> usize {
         // One directve type octet and one byte of the directive parameter field.
         let mut len = 2;
@@ -141,28 +172,15 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         }
         len += self.src_file_name.len_full();
         len += self.dest_file_name.len_full();
-        for tlv in self.options() {
+        len += self.options().len();
-            len += tlv.len_full()
-        }
         if self.crc_flag() == CrcFlag::WithCrc {
             len += 2;
         }
         len
     }
-}
 
-impl CfdpPdu for MetadataPduCreator<'_, '_, '_> {
+    /// Write [Self] to the provided buffer and returns the written size.
-    fn pdu_header(&self) -> &PduHeader {
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
-        &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 {
@@ -189,21 +207,41 @@ impl WritablePduPacket for MetadataPduCreator<'_, '_, '_> {
         current_idx += self
             .dest_file_name
             .write_to_be_bytes(&mut buf[current_idx..])?;
-        for opt in self.options() {
+        buf[current_idx..current_idx + self.options.len()].copy_from_slice(self.options);
-            opt.write_to_bytes(&mut buf[current_idx..current_idx + opt.len_full()])?;
+        current_idx += self.options.len();
-            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 {
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for MetadataPduCreator<'_, '_, '_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    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> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 /// 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
@@ -241,6 +279,7 @@ impl<'opts> Iterator for OptionsIter<'opts> {
 /// 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,
@@ -311,26 +350,36 @@ impl<'raw> MetadataPduReader<'raw> {
         })
     }
 
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    #[inline]
     pub fn options(&self) -> &'raw [u8] {
         self.options
     }
 
+    #[inline]
     pub fn metadata_params(&self) -> &MetadataGenericParams {
         &self.metadata_params
     }
 
-    pub fn src_file_name(&self) -> Lv {
+    #[inline]
+    pub fn src_file_name(&self) -> Lv<'_> {
         self.src_file_name
     }
 
-    pub fn dest_file_name(&self) -> Lv {
+    #[inline]
+    pub fn dest_file_name(&self) -> Lv<'_> {
         self.dest_file_name
     }
 }
 
 impl CfdpPdu for MetadataPduReader<'_> {
+    #[inline]
     fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
+        self.pdu_header()
     }
 
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
@@ -352,7 +401,7 @@ pub mod tests {
     };
     use crate::cfdp::pdu::{CfdpPdu, PduError, WritablePduPacket};
     use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
-    use crate::cfdp::tlv::{Tlv, TlvType};
+    use crate::cfdp::tlv::{ReadableTlv, Tlv, TlvOwned, TlvType, WritableTlv};
     use crate::cfdp::{
         ChecksumType, CrcFlag, Direction, LargeFileFlag, PduType, SegmentMetadataFlag,
         SegmentationControl, TransmissionMode,
@@ -362,18 +411,18 @@ pub mod tests {
     const SRC_FILENAME: &str = "hello-world.txt";
     const DEST_FILENAME: &str = "hello-world2.txt";
 
-    fn generic_metadata_pdu<'opts>(
+    fn generic_metadata_pdu(
         crc_flag: CrcFlag,
         checksum_type: ChecksumType,
         closure_requested: bool,
         fss: LargeFileFlag,
-        opts: &'opts [Tlv],
+        opts: &[u8],
     ) -> (
         Lv<'static>,
         Lv<'static>,
-        MetadataPduCreator<'static, 'static, 'opts>,
+        MetadataPduCreator<'static, 'static, '_>,
     ) {
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        let pdu_header = PduHeader::new_for_file_directive(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 =
@@ -541,9 +590,9 @@ pub mod tests {
         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();
+        let opts = written.options_iter();
-        for (tlv_written, tlv_read) in opts.iter().zip(read.options_iter().unwrap()) {
+        for (tlv_written, tlv_read) in opts.zip(read.options_iter().unwrap()) {
-            assert_eq!(tlv_written, &tlv_read);
+            assert_eq!(&tlv_written, &tlv_read);
         }
     }
 
@@ -658,14 +707,14 @@ pub mod tests {
         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 tlv_buf: [u8; 64] = [0; 64];
-        let opts_len = tlv1.len_full() + tlv2.len_full();
+        let opts_len = build_metadata_opts_from_slice(&mut tlv_buf, &[tlv1, tlv2]).unwrap();
         let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
             CrcFlag::NoCrc,
             ChecksumType::Crc32,
             false,
             LargeFileFlag::Normal,
-            &tlv_vec,
+            &tlv_buf[0..opts_len],
         );
         let mut buf: [u8; 128] = [0; 128];
         let write_res = metadata_pdu.write_to_bytes(&mut buf);
@@ -688,7 +737,55 @@ pub mod tests {
         let opts_iter = opts_iter.unwrap();
         let mut accumulated_len = 0;
         for (idx, opt) in opts_iter.enumerate() {
-            assert_eq!(tlv_vec[idx], opt);
+            if idx == 0 {
+                assert_eq!(tlv1, opt);
+            } else if idx == 1 {
+                assert_eq!(tlv2, opt);
+            }
+            accumulated_len += opt.len_full();
+        }
+        assert_eq!(accumulated_len, pdu_read_back.options().len());
+    }
+    #[test]
+    fn test_with_owned_opts() {
+        let tlv1 = TlvOwned::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = TlvOwned::new(TlvType::MsgToUser, &msg_to_user);
+        let mut all_tlvs = tlv1.to_vec();
+        all_tlvs.extend(tlv2.to_vec());
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Normal,
+            &all_tlvs,
+        );
+        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()
+                + all_tlvs.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() {
+            if idx == 0 {
+                assert_eq!(tlv1, opt);
+            } else if idx == 1 {
+                assert_eq!(tlv2, opt);
+            }
             accumulated_len += opt.len_full();
         }
         assert_eq!(accumulated_len, pdu_read_back.options().len());
@@ -713,7 +810,7 @@ pub mod tests {
             assert_eq!(expected, Some(FileDirectiveType::MetadataPdu));
             assert_eq!(
                 error.to_string(),
-                "invalid directive type value 255, expected Some(MetadataPdu)"
+                "invalid directive type, found 255, expected Some(MetadataPdu)"
             );
         } else {
             panic!("Expected InvalidDirectiveType error, got {:?}", error);
@@ -739,7 +836,7 @@ pub mod tests {
             assert_eq!(expected, FileDirectiveType::MetadataPdu);
             assert_eq!(
                 error.to_string(),
-                "found directive type EofPdu, expected MetadataPdu"
+                "wrong directive type, found EofPdu, expected MetadataPdu"
             );
         } else {
             panic!("Expected InvalidDirectiveType error, got {:?}", error);

src/cfdp/pdu/mod.rs

@@ -1,13 +1,12 @@
 //! CFDP Packet Data Unit (PDU) support.
+use crate::cfdp::pdu::ack::InvalidAckedDirectiveCodeError;
+use crate::cfdp::pdu::nak::InvalidStartOrEndOfScopeError;
 use crate::cfdp::*;
+use crate::crc::CRC_CCITT_FALSE;
 use crate::util::{UnsignedByteField, UnsignedByteFieldU8, UnsignedEnum};
 use crate::ByteConversionError;
-use crate::CRC_CCITT_FALSE;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
-use core::fmt::{Display, Formatter};
-#[cfg(feature = "std")]
-use std::error::Error;
 
 pub mod ack;
 pub mod eof;
@@ -18,6 +17,7 @@ pub mod nak;
 
 #[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 FileDirectiveType {
     EofPdu = 0x04,
@@ -29,137 +29,73 @@ pub enum FileDirectiveType {
     KeepAlivePdu = 0x0c,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PduError {
-    ByteConversion(ByteConversionError),
+    #[error("byte conversion error: {0}")]
-    /// Found version ID invalid, not equal to [CFDP_VERSION_2].
+    ByteConversion(#[from] ByteConversionError),
+    /// Found version ID invalid, not equal to [super::CFDP_VERSION_2].
+    #[error("CFDP version missmatch, found {0}, expected {ver}", ver = super::CFDP_VERSION_2)]
     CfdpVersionMissmatch(u8),
     /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    #[error("invalid PDU entity ID length {0}, only [1, 2, 4, 8] are allowed")]
     InvalidEntityLen(u8),
     /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    #[error("invalid transaction ID length {0}")]
     InvalidTransactionSeqNumLen(u8),
+    #[error(
+        "missmatch of PDU source ID length {src_id_len} and destination ID length {dest_id_len}"
+    )]
     SourceDestIdLenMissmatch {
         src_id_len: usize,
         dest_id_len: usize,
     },
     /// Wrong directive type, for example when parsing the directive field for a file directive
     /// PDU.
+    #[error("wrong directive type, found {found:?}, expected {expected:?}")]
     WrongDirectiveType {
         found: FileDirectiveType,
         expected: FileDirectiveType,
     },
     /// The directive type field contained a value not in the range of permitted values. This can
-    /// also happen if an invalid value is passed to the ACK PDU constructor.
+    /// also happen if an invalid value is passed to the ACK PDU reader.
+    #[error("invalid directive type, found {found:?}, expected {expected:?}")]
     InvalidDirectiveType {
         found: u8,
         expected: Option<FileDirectiveType>,
     },
-    InvalidStartOrEndOfScopeValue,
+    #[error("nak pdu: {0}")]
+    InvalidStartOrEndOfScope(#[from] InvalidStartOrEndOfScopeError),
     /// Invalid condition code. Contains the raw detected value.
+    #[error("invalid condition code {0}")]
     InvalidConditionCode(u8),
     /// Invalid checksum type which is not part of the checksums listed in the
     /// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/).
+    #[error("invalid checksum type {0}")]
     InvalidChecksumType(u8),
+    #[error("file size {0} too large")]
     FileSizeTooLarge(u64),
     /// If the CRC flag for a PDU is enabled and the checksum check fails. Contains raw 16-bit CRC.
-    ChecksumError(u16),
+    #[error("checksum error for checksum {0}")]
+    Checksum(u16),
     /// Generic error for invalid PDU formats.
-    FormatError,
+    #[error("generic PDU format error")]
+    Format,
     /// Error handling a TLV field.
-    TlvLvError(TlvLvError),
+    #[error("PDU error: {0}")]
+    TlvLv(#[from] TlvLvError),
 }
 
-impl Display for PduError {
+impl From<InvalidAckedDirectiveCodeError> for PduError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+    fn from(value: InvalidAckedDirectiveCodeError) -> Self {
-        match self {
+        Self::InvalidDirectiveType {
-            PduError::InvalidEntityLen(raw_id) => {
+            found: value.0 as u8,
-                write!(
+            expected: None,
-                    f,
-                    "invalid PDU entity ID length {raw_id}, only [1, 2, 4, 8] are allowed"
-                )
-            }
-            PduError::InvalidStartOrEndOfScopeValue => {
-                write!(f, "invalid start or end of scope for NAK PDU")
-            }
-            PduError::InvalidTransactionSeqNumLen(raw_id) => {
-                write!(
-                    f,
-                    "invalid PDUtransaction seq num length {raw_id}, only [1, 2, 4, 8] are allowed"
-                )
-            }
-            PduError::CfdpVersionMissmatch(raw) => {
-                write!(
-                    f,
-                    "cfdp version missmatch, found {raw}, expected {CFDP_VERSION_2}"
-                )
-            }
-            PduError::SourceDestIdLenMissmatch {
-                src_id_len,
-                dest_id_len,
-            } => {
-                write!(
-                    f,
-                    "missmatch of PDU source length {src_id_len} and destination length {dest_id_len}"
-                )
-            }
-            PduError::ByteConversion(e) => {
-                write!(f, "{}", e)
-            }
-            PduError::FileSizeTooLarge(value) => {
-                write!(f, "file size value {value} exceeds allowed 32 bit width")
-            }
-            PduError::WrongDirectiveType { found, expected } => {
-                write!(f, "found directive type {found:?}, expected {expected:?}")
-            }
-            PduError::InvalidConditionCode(raw_code) => {
-                write!(f, "found invalid condition code with raw value {raw_code}")
-            }
-            PduError::InvalidDirectiveType { found, expected } => {
-                write!(
-                    f,
-                    "invalid directive type value {found}, expected {expected:?}"
-                )
-            }
-            PduError::InvalidChecksumType(checksum_type) => {
-                write!(f, "invalid checksum type {checksum_type}")
-            }
-            PduError::ChecksumError(checksum) => {
-                write!(f, "checksum error for CRC {checksum:#04x}")
-            }
-            PduError::TlvLvError(error) => {
-                write!(f, "pdu tlv error: {error}")
-            }
-            PduError::FormatError => {
-                write!(f, "generic PDU format error")
-            }
         }
     }
 }
 
-#[cfg(feature = "std")]
-impl Error for PduError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        match self {
-            PduError::ByteConversion(e) => Some(e),
-            PduError::TlvLvError(e) => Some(e),
-            _ => None,
-        }
-    }
-}
-
-impl From<ByteConversionError> for PduError {
-    fn from(value: ByteConversionError) -> Self {
-        Self::ByteConversion(value)
-    }
-}
-
-impl From<TlvLvError> for PduError {
-    fn from(e: TlvLvError) -> Self {
-        Self::TlvLvError(e)
-    }
-}
-
 pub trait WritablePduPacket {
     fn len_written(&self) -> usize;
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError>;
@@ -178,33 +114,42 @@ pub trait WritablePduPacket {
 pub trait CfdpPdu {
     fn pdu_header(&self) -> &PduHeader;
 
+    #[inline]
     fn source_id(&self) -> UnsignedByteField {
         self.pdu_header().common_pdu_conf().source_entity_id
     }
 
+    #[inline]
     fn dest_id(&self) -> UnsignedByteField {
         self.pdu_header().common_pdu_conf().dest_entity_id
     }
 
+    #[inline]
     fn transaction_seq_num(&self) -> UnsignedByteField {
         self.pdu_header().common_pdu_conf().transaction_seq_num
     }
 
+    #[inline]
     fn transmission_mode(&self) -> TransmissionMode {
         self.pdu_header().common_pdu_conf().trans_mode
     }
+
+    #[inline]
     fn direction(&self) -> Direction {
         self.pdu_header().common_pdu_conf().direction
     }
 
+    #[inline]
     fn crc_flag(&self) -> CrcFlag {
         self.pdu_header().common_pdu_conf().crc_flag
     }
 
+    #[inline]
     fn file_flag(&self) -> LargeFileFlag {
         self.pdu_header().common_pdu_conf().file_flag
     }
 
+    #[inline]
     fn pdu_type(&self) -> PduType {
         self.pdu_header().pdu_type()
     }
@@ -220,6 +165,7 @@ pub trait CfdpPdu {
 /// same.
 #[derive(Debug, Copy, Clone, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct CommonPduConfig {
     source_entity_id: UnsignedByteField,
     dest_entity_id: UnsignedByteField,
@@ -232,6 +178,7 @@ pub struct CommonPduConfig {
 
 // TODO: Builder pattern might be applicable here..
 impl CommonPduConfig {
+    #[inline]
     pub fn new(
         source_id: impl Into<UnsignedByteField>,
         dest_id: impl Into<UnsignedByteField>,
@@ -263,6 +210,7 @@ impl CommonPduConfig {
         })
     }
 
+    #[inline]
     pub fn new_with_byte_fields(
         source_id: impl Into<UnsignedByteField>,
         dest_id: impl Into<UnsignedByteField>,
@@ -279,10 +227,12 @@ impl CommonPduConfig {
         )
     }
 
+    #[inline]
     pub fn source_id(&self) -> UnsignedByteField {
         self.source_entity_id
     }
 
+    #[inline]
     fn source_dest_id_check(
         source_id: impl Into<UnsignedByteField>,
         dest_id: impl Into<UnsignedByteField>,
@@ -305,6 +255,7 @@ impl CommonPduConfig {
         Ok((source_id, dest_id))
     }
 
+    #[inline]
     pub fn set_source_and_dest_id(
         &mut self,
         source_id: impl Into<UnsignedByteField>,
@@ -316,6 +267,7 @@ impl CommonPduConfig {
         Ok(())
     }
 
+    #[inline]
     pub fn dest_id(&self) -> UnsignedByteField {
         self.dest_entity_id
     }
@@ -324,6 +276,7 @@ impl CommonPduConfig {
 impl Default for CommonPduConfig {
     /// The defaults for the source ID, destination ID and the transaction sequence number is the
     /// [UnsignedByteFieldU8] with an intitial value of 0
+    #[inline]
     fn default() -> Self {
         // The new function can not fail for these input parameters.
         Self::new(
@@ -340,6 +293,7 @@ impl Default for CommonPduConfig {
 }
 
 impl PartialEq for CommonPduConfig {
+    #[inline]
     fn eq(&self, other: &Self) -> bool {
         self.source_entity_id.value() == other.source_entity_id.value()
             && self.dest_entity_id.value() == other.dest_entity_id.value()
@@ -358,6 +312,7 @@ pub const FIXED_HEADER_LEN: usize = 4;
 /// For detailed information, refer to chapter 5.1 of the CFDP standard.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PduHeader {
     pdu_type: PduType,
     pdu_conf: CommonPduConfig,
@@ -367,6 +322,9 @@ pub struct PduHeader {
 }
 
 impl PduHeader {
+    pub const FIXED_LEN: usize = FIXED_HEADER_LEN;
+
+    #[inline]
     pub fn new_for_file_data(
         pdu_conf: CommonPduConfig,
         pdu_datafield_len: u16,
@@ -382,6 +340,7 @@ impl PduHeader {
         )
     }
 
+    #[inline]
     pub fn new_for_file_data_default(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
         Self::new_generic(
             PduType::FileData,
@@ -391,7 +350,9 @@ impl PduHeader {
             SegmentationControl::NoRecordBoundaryPreservation,
         )
     }
-    pub fn new_no_file_data(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
+
+    #[inline]
+    pub fn new_for_file_directive(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
         Self::new_generic(
             PduType::FileDirective,
             pdu_conf,
@@ -401,6 +362,18 @@ impl PduHeader {
         )
     }
 
+    #[inline]
+    pub fn from_pdu_conf_for_file_directive(pdu_conf: CommonPduConfig) -> Self {
+        Self::new_generic(
+            PduType::FileDirective,
+            pdu_conf,
+            0,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        )
+    }
+
+    #[inline]
     pub fn new_generic(
         pdu_type: PduType,
         pdu_conf: CommonPduConfig,
@@ -418,6 +391,7 @@ impl PduHeader {
     }
 
     /// Returns only the length of the PDU header when written to a raw buffer.
+    #[inline]
     pub fn header_len(&self) -> usize {
         FIXED_HEADER_LEN
             + self.pdu_conf.source_entity_id.size()
@@ -425,25 +399,26 @@ impl PduHeader {
             + self.pdu_conf.dest_entity_id.size()
     }
 
+    #[inline]
     pub fn pdu_datafield_len(&self) -> usize {
         self.pdu_datafield_len.into()
     }
 
     /// Returns the full length of the PDU when written to a raw buffer, which is the header length
     /// plus the PDU datafield length.
+    #[inline]
     pub fn pdu_len(&self) -> usize {
         self.header_len() + self.pdu_datafield_len as usize
     }
 
-    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
-        // Internal note: There is currently no way to pass a PDU configuration like this, but
+        // The API does not allow passing entity IDs with different sizes, so this should
-        // this check is still kept for defensive programming.
+        // never happen.
-        if self.pdu_conf.source_entity_id.size() != self.pdu_conf.dest_entity_id.size() {
+        assert_eq!(
-            return Err(PduError::SourceDestIdLenMissmatch {
+            self.pdu_conf.source_entity_id.size(),
-                src_id_len: self.pdu_conf.source_entity_id.size(),
+            self.pdu_conf.dest_entity_id.size(),
-                dest_id_len: self.pdu_conf.dest_entity_id.size(),
+            "unexpected missmatch of source and destination entity ID length"
-            });
+        );
-        }
         if buf.len()
             < FIXED_HEADER_LEN
                 + self.pdu_conf.source_entity_id.size()
@@ -452,8 +427,7 @@ impl PduHeader {
             return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: FIXED_HEADER_LEN,
-            }
+            });
-            .into());
         }
         let mut current_idx = 0;
         buf[current_idx] = (CFDP_VERSION_2 << 5)
@@ -503,7 +477,7 @@ impl PduHeader {
             let mut digest = CRC_CCITT_FALSE.digest();
             digest.update(&buf[..self.pdu_len()]);
             if digest.finalize() != 0 {
-                return Err(PduError::ChecksumError(u16::from_be_bytes(
+                return Err(PduError::Checksum(u16::from_be_bytes(
                     buf[self.pdu_len() - 2..self.pdu_len()].try_into().unwrap(),
                 )));
             }
@@ -603,17 +577,23 @@ impl PduHeader {
             current_idx,
         ))
     }
+
+    #[inline]
     pub fn pdu_type(&self) -> PduType {
         self.pdu_type
     }
 
+    #[inline]
     pub fn common_pdu_conf(&self) -> &CommonPduConfig {
         &self.pdu_conf
     }
 
+    #[inline]
     pub fn seg_metadata_flag(&self) -> SegmentMetadataFlag {
         self.seg_metadata_flag
     }
+
+    #[inline]
     pub fn seg_ctrl(&self) -> SegmentationControl {
         self.seg_ctrl
     }
@@ -778,7 +758,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         assert_eq!(pdu_header.pdu_type(), PduType::FileDirective);
         let common_conf_ref = pdu_header.common_pdu_conf();
         assert_eq!(*common_conf_ref, common_pdu_cfg);
@@ -844,7 +824,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -861,7 +841,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -934,7 +914,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -947,7 +927,7 @@ mod tests {
             assert_eq!(raw_version, CFDP_VERSION_2 + 1);
             assert_eq!(
                 error.to_string(),
-                "cfdp version missmatch, found 2, expected 1"
+                "CFDP version missmatch, found 2, expected 1"
             );
         } else {
             panic!("invalid exception: {}", error);
@@ -979,7 +959,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -995,7 +975,7 @@ mod tests {
             assert_eq!(expected, 7);
             assert_eq!(
                 error.to_string(),
-                "source slice with size 6 too small, expected at least 7 bytes"
+                "byte conversion error: source slice with size 6 too small, expected at least 7 bytes"
             );
         }
     }
@@ -1050,7 +1030,7 @@ mod tests {
             assert_eq!(dest_id_len, 2);
             assert_eq!(
                 error.to_string(),
-                "missmatch of PDU source length 1 and destination length 2"
+                "missmatch of PDU source ID length 1 and destination ID length 2"
             );
         }
     }
@@ -1062,7 +1042,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -1086,7 +1066,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -1118,4 +1098,12 @@ mod tests {
         let common_pdu_cfg_1 = common_pdu_cfg_0;
         assert_eq!(common_pdu_cfg_0, common_pdu_cfg_1);
     }
+
+    #[test]
+    fn test_ctor_from_pdu_conf() {
+        assert_eq!(
+            PduHeader::from_pdu_conf_for_file_directive(CommonPduConfig::default()),
+            PduHeader::new_for_file_directive(CommonPduConfig::default(), 0)
+        );
+    }
 }

src/cfdp/tlv/mod.rs

@@ -9,10 +9,14 @@ use crate::ByteConversionError;
 use alloc::vec;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
+#[cfg(feature = "alloc")]
+pub use alloc_mod::*;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+use super::{InvalidTlvTypeFieldError, TlvLvDataTooLargeError};
+
 pub mod msg_to_user;
 
 pub const MIN_TLV_LEN: usize = 2;
@@ -22,6 +26,7 @@ pub trait GenericTlv {
 
     /// Checks whether the type field contains one of the standard types specified in the CFDP
     /// standard and is part of the [TlvType] enum.
+    #[inline]
     fn is_standard_tlv(&self) -> bool {
         if let TlvTypeField::Standard(_) = self.tlv_type_field() {
             return true;
@@ -30,6 +35,7 @@ pub trait GenericTlv {
     }
 
     /// Returns the standard TLV type if the TLV field is not a custom field
+    #[inline]
     fn tlv_type(&self) -> Option<TlvType> {
         if let TlvTypeField::Standard(tlv_type) = self.tlv_type_field() {
             Some(tlv_type)
@@ -39,6 +45,29 @@ pub trait GenericTlv {
     }
 }
 
+pub trait ReadableTlv {
+    fn value(&self) -> &[u8];
+
+    /// Checks whether the value field is empty.
+    #[inline]
+    fn is_empty(&self) -> bool {
+        self.value().is_empty()
+    }
+
+    /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
+    /// [Self::value]
+    #[inline]
+    fn len_value(&self) -> usize {
+        self.value().len()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    #[inline]
+    fn len_full(&self) -> usize {
+        self.len_value() + 2
+    }
+}
+
 pub trait WritableTlv {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
     fn len_written(&self) -> usize;
@@ -52,6 +81,7 @@ pub trait WritableTlv {
 
 #[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 TlvType {
     FilestoreRequest = 0x00,
@@ -64,6 +94,7 @@ pub enum TlvType {
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum TlvTypeField {
     Standard(TlvType),
     Custom(u8),
@@ -71,6 +102,7 @@ pub enum TlvTypeField {
 
 #[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 FilestoreActionCode {
     CreateFile = 0b0000,
@@ -118,6 +150,7 @@ impl From<TlvTypeField> for u8 {
 ///    this will be the lifetime of that data reference.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct Tlv<'data> {
     tlv_type_field: TlvTypeField,
     #[cfg_attr(feature = "serde", serde(borrow))]
@@ -125,14 +158,19 @@ pub struct Tlv<'data> {
 }
 
 impl<'data> Tlv<'data> {
-    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvError> {
+    pub const MIN_LEN: usize = MIN_TLV_LEN;
+
+    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv<'_>, TlvLvDataTooLargeError> {
         Ok(Tlv {
             tlv_type_field: TlvTypeField::Standard(tlv_type),
             lv: Lv::new(data)?,
         })
     }
 
-    pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Result<Tlv, TlvLvError> {
+    pub fn new_with_custom_type(
+        tlv_type: u8,
+        data: &[u8],
+    ) -> Result<Tlv<'_>, TlvLvDataTooLargeError> {
         Ok(Tlv {
             tlv_type_field: TlvTypeField::Custom(tlv_type),
             lv: Lv::new(data)?,
@@ -147,31 +185,11 @@ impl<'data> Tlv<'data> {
         }
     }
 
-    pub fn value(&self) -> &[u8] {
-        self.lv.value()
-    }
-
-    /// Checks whether the value field is empty.
-    pub fn is_empty(&self) -> bool {
-        self.value().is_empty()
-    }
-
-    /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
-    /// [Self::value]
-    pub fn len_value(&self) -> usize {
-        self.value().len()
-    }
-
-    /// Returns the full raw length, including the length byte.
-    pub fn len_full(&self) -> usize {
-        self.len_value() + 2
-    }
-
     /// Creates a TLV give a raw bytestream. Please note that is is not necessary to pass the
     /// bytestream with the exact size of the expected TLV. This function will take care
     /// of parsing the length byte, and the length of the parsed TLV can be retrieved using
     /// [Self::len_full].
-    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, ByteConversionError> {
         generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
         let mut tlv = Self {
             tlv_type_field: TlvTypeField::from(buf[0]),
@@ -185,9 +203,31 @@ impl<'data> Tlv<'data> {
 
     /// 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.
+    #[inline]
     pub fn raw_data(&self) -> Option<&[u8]> {
         self.lv.raw_data()
     }
+
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        TlvOwned {
+            tlv_type_field: self.tlv_type_field,
+            data: self.value().to_vec(),
+        }
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl PartialEq<TlvOwned> for Tlv<'_> {
+    fn eq(&self, other: &TlvOwned) -> bool {
+        self.tlv_type_field == other.tlv_type_field && self.value() == other.value()
+    }
+}
+
+impl ReadableTlv for Tlv<'_> {
+    fn value(&self) -> &[u8] {
+        self.lv.value()
+    }
 }
 
 impl WritableTlv for Tlv<'_> {
@@ -197,38 +237,127 @@ impl WritableTlv for Tlv<'_> {
         self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
         Ok(self.len_full())
     }
+
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 }
 
 impl GenericTlv for Tlv<'_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         self.tlv_type_field
     }
 }
 
-pub(crate) fn verify_tlv_type(raw_type: u8, expected_tlv_type: TlvType) -> Result<(), TlvLvError> {
+#[cfg(feature = "alloc")]
-    let tlv_type = TlvType::try_from(raw_type).map_err(|_| TlvLvError::InvalidTlvTypeField {
+pub mod alloc_mod {
-        found: raw_type,
+    use super::*;
-        expected: Some(expected_tlv_type.into()),
+
-    })?;
+    /// Owned variant of [Tlv] which is consequently [Clone]able and does not have a lifetime
-    if tlv_type != expected_tlv_type {
+    /// associated to a data slice.
-        return Err(TlvLvError::InvalidTlvTypeField {
+    #[derive(Debug, Clone, PartialEq, Eq)]
-            found: tlv_type as u8,
+    #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
-            expected: Some(expected_tlv_type as u8),
+    #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-        });
+    pub struct TlvOwned {
+        pub(crate) tlv_type_field: TlvTypeField,
+        pub(crate) data: Vec<u8>,
+    }
+
+    impl TlvOwned {
+        pub fn new(tlv_type: TlvType, data: &[u8]) -> Self {
+            Self {
+                tlv_type_field: TlvTypeField::Standard(tlv_type),
+                data: data.to_vec(),
+            }
+        }
+
+        pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Self {
+            Self {
+                tlv_type_field: TlvTypeField::Custom(tlv_type),
+                data: data.to_vec(),
+            }
+        }
+
+        /// Creates a TLV with an empty value field.
+        pub fn new_empty(tlv_type: TlvType) -> Self {
+            Self {
+                tlv_type_field: TlvTypeField::Standard(tlv_type),
+                data: Vec::new(),
+            }
+        }
+
+        pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+            generic_len_check_data_serialization(buf, self.data.len(), MIN_TLV_LEN)?;
+            buf[0] = self.tlv_type_field.into();
+            buf[1] = self.data.len() as u8;
+            buf[2..2 + self.data.len()].copy_from_slice(&self.data);
+            Ok(self.len_written())
+        }
+
+        #[inline]
+        fn len_written(&self) -> usize {
+            self.data.len() + 2
+        }
+
+        pub fn as_tlv(&self) -> Tlv<'_> {
+            Tlv {
+                tlv_type_field: self.tlv_type_field,
+                // The API should ensure that the data length is never to large, so the unwrap for the
+                // LV creation should never be an issue.
+                lv: Lv::new(&self.data).expect("lv creation failed unexpectedly"),
+            }
+        }
+    }
+
+    impl ReadableTlv for TlvOwned {
+        #[inline]
+        fn value(&self) -> &[u8] {
+            &self.data
+        }
+    }
+
+    impl WritableTlv for TlvOwned {
+        fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+            self.write_to_bytes(buf)
+        }
+
+        #[inline]
+        fn len_written(&self) -> usize {
+            self.len_written()
+        }
+    }
+
+    impl GenericTlv for TlvOwned {
+        #[inline]
+        fn tlv_type_field(&self) -> TlvTypeField {
+            self.tlv_type_field
+        }
+    }
+
+    impl From<Tlv<'_>> for TlvOwned {
+        fn from(value: Tlv<'_>) -> Self {
+            value.to_owned()
+        }
+    }
+
+    impl PartialEq<Tlv<'_>> for TlvOwned {
+        fn eq(&self, other: &Tlv) -> bool {
+            self.tlv_type_field == other.tlv_type_field && self.data == other.value()
+        }
     }
-    Ok(())
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct EntityIdTlv {
     entity_id: UnsignedByteField,
 }
 
 impl EntityIdTlv {
+    #[inline]
     pub fn new(entity_id: UnsignedByteField) -> Self {
         Self { entity_id }
     }
@@ -243,14 +372,17 @@ impl EntityIdTlv {
         Ok(())
     }
 
+    #[inline]
     pub fn entity_id(&self) -> &UnsignedByteField {
         &self.entity_id
     }
 
+    #[inline]
     pub fn len_value(&self) -> usize {
         self.entity_id.size()
     }
 
+    #[inline]
     pub fn len_full(&self) -> usize {
         2 + self.entity_id.size()
     }
@@ -268,19 +400,14 @@ impl EntityIdTlv {
     }
 
     /// Convert to a generic [Tlv], which also erases the programmatic type information.
-    pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv, ByteConversionError> {
+    pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv<'_>, ByteConversionError> {
         Self::len_check(buf)?;
         self.entity_id
             .write_to_be_bytes(&mut buf[2..2 + self.entity_id.size()])?;
-        Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.size()]).map_err(|e| match e {
+        // Can't fail.
-            TlvLvError::ByteConversion(e) => e,
+        Ok(Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.size()]).unwrap())
-            // All other errors are impossible.
-            _ => panic!("unexpected TLV error"),
-        })
     }
-}
 
-impl WritableTlv for EntityIdTlv {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         Self::len_check(buf)?;
         buf[0] = TlvType::EntityId as u8;
@@ -288,35 +415,50 @@ impl WritableTlv for EntityIdTlv {
         Ok(2 + self.entity_id.write_to_be_bytes(&mut buf[2..])?)
     }
 
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 }
 
+impl WritableTlv for EntityIdTlv {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.write_to_bytes(buf)
+    }
+
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 impl GenericTlv for EntityIdTlv {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         TlvTypeField::Standard(TlvType::EntityId)
     }
 }
 
-impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
+impl TryFrom<Tlv<'_>> for EntityIdTlv {
     type Error = TlvLvError;
 
-    fn try_from(value: Tlv) -> Result<Self, Self::Error> {
+    fn try_from(value: Tlv) -> Result<Self, TlvLvError> {
         match value.tlv_type_field {
             TlvTypeField::Standard(tlv_type) => {
                 if tlv_type != TlvType::EntityId {
-                    return Err(TlvLvError::InvalidTlvTypeField {
+                    return Err(InvalidTlvTypeFieldError {
                         found: tlv_type as u8,
                         expected: Some(TlvType::EntityId as u8),
-                    });
+                    }
+                    .into());
                 }
             }
             TlvTypeField::Custom(val) => {
-                return Err(TlvLvError::InvalidTlvTypeField {
+                return Err(InvalidTlvTypeFieldError {
                     found: val,
                     expected: Some(TlvType::EntityId as u8),
-                });
+                }
+                .into());
             }
         }
         let len_value = value.value().len();
@@ -336,6 +478,7 @@ impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
     }
 }
 
+#[inline]
 pub fn fs_request_has_second_filename(action_code: FilestoreActionCode) -> bool {
     if action_code == FilestoreActionCode::RenameFile
         || action_code == FilestoreActionCode::AppendFile
@@ -348,6 +491,7 @@ pub fn fs_request_has_second_filename(action_code: FilestoreActionCode) -> bool
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 struct FilestoreTlvBase<'first_name, 'second_name> {
     pub action_code: FilestoreActionCode,
     #[cfg_attr(feature = "serde", serde(borrow))]
@@ -357,6 +501,7 @@ struct FilestoreTlvBase<'first_name, 'second_name> {
 }
 
 impl FilestoreTlvBase<'_, '_> {
+    #[inline]
     fn base_len_value(&self) -> usize {
         let mut len = 1 + self.first_name.len_full();
         if let Some(second_name) = self.second_name {
@@ -466,22 +611,27 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
         })
     }
 
+    #[inline]
     pub fn action_code(&self) -> FilestoreActionCode {
         self.base.action_code
     }
 
+    #[inline]
     pub fn first_name(&self) -> Lv<'first_name> {
         self.base.first_name
     }
 
+    #[inline]
     pub fn second_name(&self) -> Option<Lv<'second_name>> {
         self.base.second_name
     }
 
+    #[inline]
     pub fn len_value(&self) -> usize {
         self.base.base_len_value()
     }
 
+    #[inline]
     pub fn len_full(&self) -> usize {
         2 + self.len_value()
     }
@@ -520,9 +670,7 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
             },
         })
     }
-}
 
-impl WritableTlv for FilestoreRequestTlv<'_, '_> {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.len_full() {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -548,12 +696,25 @@ impl WritableTlv for FilestoreRequestTlv<'_, '_> {
         Ok(current_idx)
     }
 
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 }
 
+impl WritableTlv for FilestoreRequestTlv<'_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.write_to_bytes(buf)
+    }
+
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 impl GenericTlv for FilestoreRequestTlv<'_, '_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         TlvTypeField::Standard(TlvType::FilestoreRequest)
     }
@@ -561,6 +722,7 @@ impl GenericTlv for FilestoreRequestTlv<'_, '_> {
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct FilestoreResponseTlv<'first_name, 'second_name, 'fs_msg> {
     #[cfg_attr(feature = "serde", serde(borrow))]
     base: FilestoreTlvBase<'first_name, 'second_name>,
@@ -627,26 +789,32 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
         false
     }
 
+    #[inline]
     pub fn action_code(&self) -> FilestoreActionCode {
         self.base.action_code
     }
 
+    #[inline]
     pub fn status_code(&self) -> u8 {
         self.status_code
     }
 
+    #[inline]
     pub fn first_name(&self) -> Lv<'first_name> {
         self.base.first_name
     }
 
+    #[inline]
     pub fn second_name(&self) -> Option<Lv<'second_name>> {
         self.base.second_name
     }
 
+    #[inline]
     pub fn len_value(&self) -> usize {
         self.base.base_len_value() + self.filestore_message.len_full()
     }
 
+    #[inline]
     pub fn len_full(&self) -> usize {
         2 + self.len_value()
     }
@@ -704,9 +872,7 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
             filestore_message,
         })
     }
-}
 
-impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.len_full() {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -739,12 +905,41 @@ impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
     }
 }
 
+impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.write_to_bytes(buf)
+    }
+
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 impl GenericTlv for FilestoreResponseTlv<'_, '_, '_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         TlvTypeField::Standard(TlvType::FilestoreResponse)
     }
 }
 
+pub(crate) fn verify_tlv_type(
+    raw_type: u8,
+    expected_tlv_type: TlvType,
+) -> Result<(), InvalidTlvTypeFieldError> {
+    let tlv_type = TlvType::try_from(raw_type).map_err(|_| InvalidTlvTypeFieldError {
+        found: raw_type,
+        expected: Some(expected_tlv_type.into()),
+    })?;
+    if tlv_type != expected_tlv_type {
+        return Err(InvalidTlvTypeFieldError {
+            found: tlv_type as u8,
+            expected: Some(expected_tlv_type as u8),
+        });
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -932,14 +1127,14 @@ mod tests {
         let tlv_res = Tlv::new(TlvType::MsgToUser, &buf_too_large);
         assert!(tlv_res.is_err());
         let error = tlv_res.unwrap_err();
-        if let TlvLvError::DataTooLarge(size) = error {
+        match error {
-            assert_eq!(size, u8::MAX as usize + 1);
+            TlvLvDataTooLargeError(size) => {
-            assert_eq!(
+                assert_eq!(size, u8::MAX as usize + 1);
-                error.to_string(),
+                assert_eq!(
-                "data with size 256 larger than allowed 255 bytes"
+                    error.to_string(),
-            );
+                    "data with size 256 larger than allowed 255 bytes"
-        } else {
+                );
-            panic!("unexpected error {:?}", error);
+            }
         }
     }
 
@@ -1249,7 +1444,8 @@ mod tests {
         let error = EntityIdTlv::try_from(msg_to_user_tlv);
         assert!(error.is_err());
         let error = error.unwrap_err();
-        if let TlvLvError::InvalidTlvTypeField { found, expected } = error {
+        if let TlvLvError::InvalidTlvTypeField(InvalidTlvTypeFieldError { found, expected }) = error
+        {
             assert_eq!(found, TlvType::MsgToUser as u8);
             assert_eq!(expected, Some(TlvType::EntityId as u8));
             assert_eq!(
@@ -1293,4 +1489,71 @@ mod tests {
         assert_eq!(tlv_as_vec[0], 20);
         assert_eq!(tlv_as_vec[1], 0);
     }
+
+    #[test]
+    fn test_tlv_to_owned() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
+        assert!(tlv_res.is_ok());
+        let tlv_res = tlv_res.unwrap();
+        let tlv_owned = tlv_res.to_owned();
+        assert_eq!(tlv_res, tlv_owned);
+        let tlv_owned_from_conversion: TlvOwned = tlv_res.into();
+        assert_eq!(tlv_owned_from_conversion, tlv_owned);
+        assert_eq!(tlv_owned_from_conversion, tlv_res);
+    }
+
+    #[test]
+    fn test_owned_tlv() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = TlvOwned::new(TlvType::EntityId, &buf[0..1]);
+        assert_eq!(
+            tlv_res.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::EntityId)
+        );
+        assert_eq!(tlv_res.len_full(), 3);
+        assert_eq!(tlv_res.value().len(), 1);
+        assert_eq!(tlv_res.len_value(), 1);
+        assert!(!tlv_res.is_empty());
+        assert_eq!(tlv_res.value()[0], 5);
+    }
+
+    #[test]
+    fn test_owned_tlv_empty() {
+        let tlv_res = TlvOwned::new_empty(TlvType::FlowLabel);
+        assert_eq!(
+            tlv_res.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::FlowLabel)
+        );
+        assert_eq!(tlv_res.len_full(), 2);
+        assert_eq!(tlv_res.value().len(), 0);
+        assert_eq!(tlv_res.len_value(), 0);
+        assert!(tlv_res.is_empty());
+    }
+
+    #[test]
+    fn test_owned_tlv_custom_type() {
+        let tlv_res = TlvOwned::new_with_custom_type(32, &[]);
+        assert_eq!(tlv_res.tlv_type_field(), TlvTypeField::Custom(32));
+        assert_eq!(tlv_res.len_full(), 2);
+        assert_eq!(tlv_res.value().len(), 0);
+        assert_eq!(tlv_res.len_value(), 0);
+        assert!(tlv_res.is_empty());
+    }
+
+    #[test]
+    fn test_owned_tlv_conversion_to_bytes() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
+        assert!(tlv_res.is_ok());
+        let tlv_res = tlv_res.unwrap();
+        let tlv_owned_from_conversion: TlvOwned = tlv_res.into();
+        assert_eq!(tlv_res.to_vec(), tlv_owned_from_conversion.to_vec());
+    }
 }

src/cfdp/tlv/msg_to_user.rs

@@ -1,6 +1,11 @@
 //! Abstractions for the Message to User CFDP TLV subtype.
-use super::{GenericTlv, Tlv, TlvLvError, TlvType, TlvTypeField, WritableTlv};
+#[cfg(feature = "alloc")]
-use crate::ByteConversionError;
+use super::TlvOwned;
+use super::{GenericTlv, ReadableTlv, Tlv, TlvLvError, TlvType, TlvTypeField, WritableTlv};
+use crate::{
+    cfdp::{InvalidTlvTypeFieldError, TlvLvDataTooLargeError},
+    ByteConversionError,
+};
 use delegate::delegate;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
@@ -10,7 +15,7 @@ pub struct MsgToUserTlv<'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> {
+    pub fn new(value: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvDataTooLargeError> {
         Ok(Self {
             tlv: Tlv::new(TlvType::MsgToUser, value)?,
         })
@@ -32,10 +37,12 @@ impl<'data> MsgToUserTlv<'data> {
         }
     }
 
+    #[inline]
     pub fn is_standard_tlv(&self) -> bool {
         true
     }
 
+    #[inline]
     pub fn tlv_type(&self) -> Option<TlvType> {
         Some(TlvType::MsgToUser)
     }
@@ -60,36 +67,65 @@ impl<'data> MsgToUserTlv<'data> {
         match msg_to_user.tlv.tlv_type_field() {
             TlvTypeField::Standard(tlv_type) => {
                 if tlv_type != TlvType::MsgToUser {
-                    return Err(TlvLvError::InvalidTlvTypeField {
+                    return Err(InvalidTlvTypeFieldError {
                         found: tlv_type as u8,
                         expected: Some(TlvType::MsgToUser as u8),
-                    });
+                    }
+                    .into());
                 }
             }
             TlvTypeField::Custom(raw) => {
-                return Err(TlvLvError::InvalidTlvTypeField {
+                return Err(InvalidTlvTypeFieldError {
                     found: raw,
                     expected: Some(TlvType::MsgToUser as u8),
-                });
+                }
+                .into());
             }
         }
         Ok(msg_to_user)
     }
-}
 
-impl WritableTlv for MsgToUserTlv<'_> {
+    #[inline]
+    pub fn to_tlv(&self) -> Tlv<'data> {
+        self.tlv
+    }
+
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        self.tlv.to_owned()
+    }
+
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 
     delegate!(
         to self.tlv {
-            fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+            pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
         }
     );
 }
 
+impl<'a> From<MsgToUserTlv<'a>> for Tlv<'a> {
+    fn from(value: MsgToUserTlv<'a>) -> Tlv<'a> {
+        value.to_tlv()
+    }
+}
+
+impl WritableTlv for MsgToUserTlv<'_> {
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.tlv.write_to_bytes(buf)
+    }
+}
+
 impl GenericTlv for MsgToUserTlv<'_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         self.tlv.tlv_type_field()
     }
@@ -139,6 +175,40 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_msg_to_user_type_reduction() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let tlv = msg_to_user.to_tlv();
+        assert_eq!(
+            tlv.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+
+        assert_eq!(tlv.value(), custom_value);
+    }
+
+    #[test]
+    fn test_msg_to_user_to_tlv() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let tlv: Tlv = msg_to_user.into();
+        assert_eq!(msg_to_user.to_tlv(), tlv);
+    }
+
+    #[test]
+    fn test_msg_to_user_owner_converter() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let tlv = msg_to_user.to_owned();
+        assert_eq!(
+            tlv.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+
+        assert_eq!(tlv.value(), custom_value);
+    }
+
     #[test]
     fn test_reserved_msg_deserialization() {
         let custom_value: [u8; 3] = [1, 2, 3];
@@ -154,9 +224,9 @@ mod tests {
     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 {
+        if let TlvLvError::InvalidTlvTypeField(inner) = error {
-            assert_eq!(found, TlvType::FlowLabel as u8);
+            assert_eq!(inner.found, TlvType::FlowLabel as u8);
-            assert_eq!(expected, Some(TlvType::MsgToUser as u8));
+            assert_eq!(inner.expected, Some(TlvType::MsgToUser as u8));
         } else {
             panic!("Wrong error type returned: {:?}", error);
         }

src/crc.rs

@@ -0,0 +1,11 @@
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
+/// a [crc::NoTable] as the CRC implementation.
+pub const CRC_CCITT_FALSE_NO_TABLE: crc::Crc<u16, crc::NoTable> =
+    crc::Crc::<u16, crc::NoTable>::new(&crc::CRC_16_IBM_3740);
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
+/// [crc::Table<1>] as the CRC implementation.
+pub const CRC_CCITT_FALSE: crc::Crc<u16> = crc::Crc::<u16>::new(&crc::CRC_16_IBM_3740);
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
+/// a [crc::Table<16>] large table as the CRC implementation.
+pub const CRC_CCITT_FALSE_BIG_TABLE: crc::Crc<u16, crc::Table<16>> =
+    crc::Crc::<u16, crc::Table<16>>::new(&crc::CRC_16_IBM_3740);

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

src/ecss/mod.rs

@@ -1,31 +1,35 @@
 //! 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 [tc] module and ithe PUS telemetry definitions
+//! You can find the PUS telecommand types in the [tc] module and the the PUS telemetry
-//! inside the [tm] module.
+//! types inside the [tm] module.
-use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
+use crate::{
+    crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE},
+    ByteConversionError, CcsdsPacket,
+};
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
-use core::fmt::{Debug, Display, Formatter};
+use arbitrary_int::u4;
+use core::fmt::Debug;
 use core::mem::size_of;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-#[cfg(feature = "std")]
-use std::error::Error;
 
 pub mod event;
 pub mod hk;
 pub mod scheduling;
 pub mod tc;
+pub mod tc_pus_a;
 pub mod tm;
+pub mod tm_pus_a;
 pub mod verification;
 
 pub type CrcType = u16;
-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))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 #[non_exhaustive]
 pub enum PusServiceId {
@@ -72,25 +76,27 @@ pub enum PusServiceId {
 }
 
 /// All PUS versions. Only PUS C is supported by this library.
-#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[derive(PartialEq, Eq, Debug, num_enum::TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u4, exhaustive = false)]
+#[repr(u8)]
 #[non_exhaustive]
 pub enum PusVersion {
     EsaPus = 0,
     PusA = 1,
     PusC = 2,
-    Invalid = 0b1111,
 }
 
-impl TryFrom<u8> for PusVersion {
+impl TryFrom<u4> for PusVersion {
-    type Error = ();
+    type Error = u4;
 
-    fn try_from(value: u8) -> Result<Self, Self::Error> {
+    fn try_from(value: u4) -> Result<Self, Self::Error> {
         match value {
-            x if x == PusVersion::EsaPus as u8 => Ok(PusVersion::EsaPus),
+            x if x == PusVersion::EsaPus.raw_value() => Ok(PusVersion::EsaPus),
-            x if x == PusVersion::PusA as u8 => Ok(PusVersion::PusA),
+            x if x == PusVersion::PusA.raw_value() => Ok(PusVersion::PusA),
-            x if x == PusVersion::PusC as u8 => Ok(PusVersion::PusC),
+            x if x == PusVersion::PusC.raw_value() => Ok(PusVersion::PusC),
-            _ => Err(()),
+            _ => Err(value),
         }
     }
 }
@@ -98,6 +104,7 @@ impl TryFrom<u8> for PusVersion {
 /// ECSS Packet Type Codes (PTC)s.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum PacketTypeCodes {
     Boolean = 1,
@@ -119,6 +126,7 @@ pub type Ptc = PacketTypeCodes;
 /// ECSS Packet Field Codes (PFC)s for the unsigned [Ptc].
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum PfcUnsigned {
     OneByte = 4,
@@ -136,6 +144,7 @@ pub enum PfcUnsigned {
 /// ECSS Packet Field Codes (PFC)s for the real (floating point) [Ptc].
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum PfcReal {
     /// 4 octets simple precision format (IEEE)
@@ -148,70 +157,42 @@ pub enum PfcReal {
     DoubleMilStd = 4,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PusError {
-    VersionNotSupported(PusVersion),
+    #[error("PUS version {0:?} not supported")]
+    VersionNotSupported(u4),
+    #[error("checksum verification for crc16 {0:#06x} failed")]
     ChecksumFailure(u16),
     /// CRC16 needs to be calculated first
-    CrcCalculationMissing,
+    //#[error("crc16 was not calculated")]
-    ByteConversion(ByteConversionError),
+    //CrcCalculationMissing,
-}
+    #[error("pus error: {0}")]
-
+    ByteConversion(#[from] ByteConversionError),
-impl Display for PusError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            PusError::VersionNotSupported(v) => {
-                write!(f, "PUS version {v:?} not supported")
-            }
-            PusError::ChecksumFailure(crc) => {
-                write!(f, "checksum verification for crc16 {crc:#06x} failed")
-            }
-            PusError::CrcCalculationMissing => {
-                write!(f, "crc16 was not calculated")
-            }
-            PusError::ByteConversion(e) => {
-                write!(f, "pus error: {e}")
-            }
-        }
-    }
-}
-
-#[cfg(feature = "std")]
-impl Error for PusError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        if let PusError::ByteConversion(e) = self {
-            return Some(e);
-        }
-        None
-    }
-}
-
-impl From<ByteConversionError> for PusError {
-    fn from(e: ByteConversionError) -> Self {
-        PusError::ByteConversion(e)
-    }
 }
 
 /// Generic trait to describe common attributes for both PUS Telecommands (TC) and PUS Telemetry
 /// (TM) packets. All PUS packets are also a special type of [CcsdsPacket]s.
 pub trait PusPacket: CcsdsPacket {
-    const PUS_VERSION: PusVersion = PusVersion::PusC;
+    fn pus_version(&self) -> Result<PusVersion, u4>;
-
-    fn pus_version(&self) -> PusVersion;
     fn service(&self) -> u8;
     fn subservice(&self) -> u8;
     fn user_data(&self) -> &[u8];
-    fn crc16(&self) -> Option<u16>;
+    /// CRC-16-CCITT checksum.
+    fn checksum(&self) -> Option<u16>;
+    /// The presence of the CRC-16-CCITT checksum is optional.
+    fn has_checksum(&self) -> bool {
+        self.checksum().is_some()
+    }
 }
 
-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(ByteConversionError::FromSliceTooSmall {
             found: raw_data.len(),
             expected: 2,
-        }
+        });
-        .into());
     }
     Ok(u16::from_be_bytes(
         raw_data[raw_data.len() - 2..raw_data.len()]
@@ -226,49 +207,45 @@ 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,
     slice: &[u8],
-) -> Result<&[u8], PusError> {
+    has_checksum: bool,
-    match current_idx {
+) -> Result<&[u8], ByteConversionError> {
-        _ if current_idx > total_len - 2 => Err(ByteConversionError::FromSliceTooSmall {
+    if has_checksum {
-            found: total_len - 2,
+        if current_idx > total_len - 2 {
-            expected: current_idx,
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: total_len - 2,
+                expected: current_idx,
+            });
         }
-        .into()),
+        Ok(&slice[current_idx..total_len - 2])
-        _ => Ok(&slice[current_idx..total_len - 2]),
+    } else {
+        Ok(&slice[current_idx..total_len])
     }
 }
 
-pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
+pub 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(|| ())
+        .then_some(())
         .ok_or(PusError::ChecksumFailure(crc16))
 }
 
-pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
+pub fn verify_crc16_ccitt_false_from_raw_to_pus_error_no_table(
+    raw_data: &[u8],
+    crc16: u16,
+) -> Result<(), PusError> {
+    verify_crc16_ccitt_false_from_raw_no_table(raw_data)
+        .then_some(())
+        .ok_or(PusError::ChecksumFailure(crc16))
+}
+
+/// Verify the CRC16 of a raw packet.
+pub 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 {
@@ -277,29 +254,30 @@ pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
     false
 }
 
-macro_rules! ccsds_impl {
+/// Verify the CRC16 of a raw packet, using the table-less implementation.
-    () => {
+pub fn verify_crc16_ccitt_false_from_raw_no_table(raw_data: &[u8]) -> bool {
-        delegate!(to self.sp_header {
+    let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
-            fn ccsds_version(&self) -> u8;
+    digest.update(raw_data);
-            fn packet_id(&self) -> crate::PacketId;
+    if digest.finalize() == 0 {
-            fn psc(&self) -> crate::PacketSequenceCtrl;
+        return true;
-            fn data_len(&self) -> u16;
-        });
     }
+    false
 }
 
 macro_rules! sp_header_impls {
     () => {
         delegate!(to self.sp_header {
-            pub fn set_apid(&mut self, apid: u16) -> bool;
+            #[inline]
-            pub fn set_seq_count(&mut self, seq_count: u16) -> bool;
+            pub fn set_apid(&mut self, apid: u11);
+            #[inline]
+            pub fn set_seq_count(&mut self, seq_count: u14);
+            #[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;
 
 /// Generic trait for ECSS enumeration which consist of a PFC field denoting their bit length
@@ -360,14 +338,20 @@ impl<TYPE: Debug + Copy + Clone + PartialEq + Eq + ToBeBytes + Into<u64>> EcssEn
 {
 }
 
+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<$ty> for $Enum {
+            impl From<$Enum> for $ty {
-                fn from(value: $ty) -> Self {
+                fn from(value: $Enum) -> Self {
-                    Self::new(value)
+                    value.value_typed()
                 }
             }
         )*
@@ -387,8 +371,47 @@ generic_ecss_enum_typedefs_and_from_impls! {
 /// byte representation. This is especially useful for generic abstractions which depend only
 /// on the serialization of those packets.
 pub trait WritablePusPacket {
+    /// The length here also includes the CRC length.
     fn len_written(&self) -> usize;
-    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+
+    /// Checksum generation is enabled for the packet.
+    fn has_checksum(&self) -> bool;
+
+    /// Writes the packet to the given slice without writing the CRC checksum.
+    ///
+    /// The returned size is the written size WITHOUT the CRC checksum.
+    /// If the checksum generation is disabled, this function is identical to the APIs which
+    /// generate a checksum.
+    fn write_to_bytes_no_checksum(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+
+    /// First uses [Self::write_to_bytes_no_checksum] to write the packet to the given slice and
+    /// then uses the [CRC_CCITT_FALSE] to calculate the CRC and write it to the slice if the
+    /// packet is configured to include a checksum.
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
+        let mut curr_idx = self.write_to_bytes_no_checksum(slice)?;
+        if self.has_checksum() {
+            let mut digest = CRC_CCITT_FALSE.digest();
+            digest.update(&slice[0..curr_idx]);
+            slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+            curr_idx += 2;
+        }
+        Ok(curr_idx)
+    }
+
+    /// First uses [Self::write_to_bytes_no_checksum] to write the packet to the given slice and then
+    /// uses the [CRC_CCITT_FALSE_NO_TABLE] to calculate the CRC and write it to the slice if
+    /// the paket is configured to include a checksum.
+    fn write_to_bytes_checksum_no_table(&self, slice: &mut [u8]) -> Result<usize, PusError> {
+        let mut curr_idx = self.write_to_bytes_no_checksum(slice)?;
+        if self.has_checksum() {
+            let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
+            digest.update(&slice[0..curr_idx]);
+            slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+            curr_idx += 2;
+        }
+        Ok(curr_idx)
+    }
+
     #[cfg(feature = "alloc")]
     fn to_vec(&self) -> Result<Vec<u8>, PusError> {
         // This is the correct way to do this. See
@@ -400,6 +423,25 @@ pub trait WritablePusPacket {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct CreatorConfig {
+    /// Set the CCSDS data length field on construction.
+    pub set_ccsds_len: bool,
+    /// CRC-16-CCITT Checksum is present.
+    pub has_checksum: bool,
+}
+
+impl Default for CreatorConfig {
+    fn default() -> Self {
+        Self {
+            set_ccsds_len: true,
+            has_checksum: true,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use alloc::string::ToString;
@@ -424,6 +466,8 @@ mod tests {
         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]);
     }
@@ -441,6 +485,8 @@ mod tests {
         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]);
     }
@@ -476,6 +522,8 @@ mod tests {
         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]);
     }
@@ -512,6 +560,8 @@ mod tests {
         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);
@@ -519,9 +569,10 @@ mod tests {
 
     #[test]
     fn test_pus_error_display() {
-        let unsupport_version = PusError::VersionNotSupported(super::PusVersion::EsaPus);
+        let unsupport_version =
+            PusError::VersionNotSupported(super::PusVersion::EsaPus.raw_value());
         let write_str = unsupport_version.to_string();
-        assert_eq!(write_str, "PUS version EsaPus not supported")
+        assert_eq!(write_str, "PUS version 0 not supported")
     }
 
     #[test]
@@ -555,8 +606,8 @@ mod tests {
     #[test]
     fn test_pus_error_eq_impl() {
         assert_eq!(
-            PusError::VersionNotSupported(PusVersion::EsaPus),
+            PusError::VersionNotSupported(PusVersion::EsaPus.raw_value()),
-            PusError::VersionNotSupported(PusVersion::EsaPus)
+            PusError::VersionNotSupported(PusVersion::EsaPus.raw_value())
         );
     }
 

src/ecss/scheduling.rs

@@ -5,6 +5,7 @@ use serde::{Deserialize, Serialize};
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum Subservice {
     // Core subservices
@@ -47,6 +48,7 @@ pub enum Subservice {
 
 /// This status applies to sub-schedules and groups as well as specified in ECSS-E-ST-70-41C 8.11.3
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum SchedStatus {
     Disabled = 0,
@@ -54,6 +56,7 @@ pub enum SchedStatus {
 }
 
 impl From<bool> for SchedStatus {
+    #[inline]
     fn from(value: bool) -> Self {
         if value {
             SchedStatus::Enabled
@@ -65,6 +68,7 @@ impl From<bool> for SchedStatus {
 
 /// Time window types as specified in  ECSS-E-ST-70-41C 8.11.3
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum TimeWindowType {
     SelectAll = 0,

src/ecss/verification.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 {
     TmAcceptanceSuccess = 1,

src/seq_count.rs

@@ -0,0 +1,437 @@
+use crate::MAX_SEQ_COUNT;
+use arbitrary_int::traits::Integer;
+use core::cell::Cell;
+use paste::paste;
+
+/// Core trait for objects which can provide a sequence count.
+///
+/// The core functions are not mutable on purpose to allow easier usage with
+/// static structs when using the interior mutability pattern. This can be achieved by using
+/// [Cell], [core::cell::RefCell] or atomic types.
+pub trait SequenceCounter {
+    type Raw: Into<u64>;
+    const MAX_BIT_WIDTH: usize;
+
+    fn get(&self) -> Self::Raw;
+
+    fn increment(&self);
+
+    fn increment_mut(&mut self) {
+        self.increment();
+    }
+
+    fn get_and_increment(&self) -> Self::Raw {
+        let val = self.get();
+        self.increment();
+        val
+    }
+
+    fn get_and_increment_mut(&mut self) -> Self::Raw {
+        self.get_and_increment()
+    }
+}
+
+#[derive(Clone)]
+pub struct SequenceCounterSimple<T: Copy> {
+    seq_count: Cell<T>,
+    // The maximum value
+    max_val: T,
+}
+
+macro_rules! impl_for_primitives {
+    ($($ty: ident,)+) => {
+        $(
+            paste! {
+                impl SequenceCounterSimple<$ty> {
+                    pub fn [<new_custom_max_val_ $ty>](max_val: $ty) -> Self {
+                        Self {
+                            seq_count: Cell::new(0),
+                            max_val,
+                        }
+                    }
+                    pub fn [<new_ $ty>]() -> Self {
+                        Self {
+                            seq_count: Cell::new(0),
+                            max_val: $ty::MAX
+                        }
+                    }
+                }
+
+                impl Default for SequenceCounterSimple<$ty> {
+                    fn default() -> Self {
+                        Self::[<new_ $ty>]()
+                    }
+                }
+
+                impl SequenceCounter for SequenceCounterSimple<$ty> {
+                    type Raw = $ty;
+                    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                    fn get(&self) -> Self::Raw {
+                        self.seq_count.get()
+                    }
+
+                    fn increment(&self) {
+                        self.get_and_increment();
+                    }
+
+                    fn get_and_increment(&self) -> Self::Raw {
+                        let curr_count = self.seq_count.get();
+
+                        if curr_count == self.max_val {
+                            self.seq_count.set(0);
+                        } else {
+                            self.seq_count.set(curr_count + 1);
+                        }
+                        curr_count
+                    }
+                }
+            }
+        )+
+    }
+}
+
+impl_for_primitives!(u8, u16, u32, u64,);
+
+/// This is a sequence count provider which wraps around at [MAX_SEQ_COUNT].
+#[derive(Clone)]
+pub struct SequenceCounterCcsdsSimple {
+    provider: SequenceCounterSimple<u16>,
+}
+
+impl Default for SequenceCounterCcsdsSimple {
+    fn default() -> Self {
+        Self {
+            provider: SequenceCounterSimple::new_custom_max_val_u16(MAX_SEQ_COUNT.as_u16()),
+        }
+    }
+}
+
+impl SequenceCounter for SequenceCounterCcsdsSimple {
+    type Raw = u16;
+    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+    delegate::delegate! {
+        to self.provider {
+            fn get(&self) -> u16;
+            fn increment(&self);
+            fn get_and_increment(&self) -> u16;
+        }
+    }
+}
+
+impl SequenceCounter for core::sync::atomic::AtomicU8 {
+    type Raw = u8;
+
+    const MAX_BIT_WIDTH: usize = 8;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl SequenceCounter for core::sync::atomic::AtomicU16 {
+    type Raw = u16;
+
+    const MAX_BIT_WIDTH: usize = 16;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl SequenceCounter for core::sync::atomic::AtomicU32 {
+    type Raw = u32;
+
+    const MAX_BIT_WIDTH: usize = 32;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(target_has_atomic = "64")]
+impl SequenceCounter for core::sync::atomic::AtomicU64 {
+    type Raw = u64;
+
+    const MAX_BIT_WIDTH: usize = 64;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl SequenceCounter for portable_atomic::AtomicU8 {
+    type Raw = u8;
+
+    const MAX_BIT_WIDTH: usize = 8;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl SequenceCounter for portable_atomic::AtomicU16 {
+    type Raw = u16;
+
+    const MAX_BIT_WIDTH: usize = 16;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl SequenceCounter for portable_atomic::AtomicU32 {
+    type Raw = u32;
+
+    const MAX_BIT_WIDTH: usize = 32;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl SequenceCounter for portable_atomic::AtomicU64 {
+    type Raw = u64;
+
+    const MAX_BIT_WIDTH: usize = 64;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+impl<T: SequenceCounter + ?Sized> SequenceCounter for &T {
+    type Raw = T::Raw;
+    const MAX_BIT_WIDTH: usize = T::MAX_BIT_WIDTH;
+
+    fn get(&self) -> Self::Raw {
+        (**self).get()
+    }
+
+    fn increment(&self) {
+        (**self).increment()
+    }
+}
+
+macro_rules! sync_clonable_seq_counter_impl {
+    ($ty: ident) => {
+        paste::paste! {
+            /// This can be used if a custom wrap value is required when using a thread-safe
+            /// atomic based sequence counter.
+            #[derive(Debug)]
+            pub struct [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                seq_count: core::sync::atomic::[<Atomic $ty:upper>],
+                max_val: $ty,
+            }
+
+            impl [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                pub fn new(max_val: $ty) -> Self {
+                    Self {
+                        seq_count: core::sync::atomic::[<Atomic $ty:upper>]::new(0),
+                        max_val,
+                    }
+                }
+            }
+
+            impl SequenceCounter for [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                type Raw = $ty;
+                const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                fn get(&self) -> $ty {
+                    self.seq_count.load(core::sync::atomic::Ordering::Relaxed)
+                }
+
+                fn increment(&self) {
+                    self.get_and_increment();
+                }
+
+                fn get_and_increment(&self) -> $ty {
+                    self.seq_count.fetch_update(
+                        core::sync::atomic::Ordering::Relaxed,
+                        core::sync::atomic::Ordering::Relaxed,
+                        |cur| {
+                            // compute the next value, wrapping at MAX_VAL
+                            let next = if cur == self.max_val { 0 } else { cur + 1 };
+                            Some(next)
+                        },
+                    ).unwrap()
+                }
+            }
+        }
+    };
+}
+
+#[cfg(target_has_atomic = "8")]
+sync_clonable_seq_counter_impl!(u8);
+#[cfg(target_has_atomic = "16")]
+sync_clonable_seq_counter_impl!(u16);
+#[cfg(target_has_atomic = "32")]
+sync_clonable_seq_counter_impl!(u32);
+#[cfg(target_has_atomic = "64")]
+sync_clonable_seq_counter_impl!(u64);
+
+#[cfg(test)]
+mod tests {
+    use core::sync::atomic::{AtomicU16, AtomicU32, AtomicU64, AtomicU8};
+
+    use crate::seq_count::{
+        SequenceCounter, SequenceCounterCcsdsSimple, SequenceCounterSimple,
+        SequenceCounterSyncCustomWrapU8,
+    };
+    use crate::MAX_SEQ_COUNT;
+
+    #[test]
+    fn test_u8_counter() {
+        let u8_counter = SequenceCounterSimple::<u8>::default();
+        assert_eq!(u8_counter.get(), 0);
+        assert_eq!(u8_counter.get_and_increment(), 0);
+        assert_eq!(u8_counter.get_and_increment(), 1);
+        assert_eq!(u8_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_u8_counter_overflow() {
+        let u8_counter = SequenceCounterSimple::new_u8();
+        for _ in 0..256 {
+            u8_counter.increment();
+        }
+        assert_eq!(u8_counter.get(), 0);
+    }
+
+    #[test]
+    fn test_ccsds_counter() {
+        let ccsds_counter = SequenceCounterCcsdsSimple::default();
+        assert_eq!(ccsds_counter.get(), 0);
+        assert_eq!(ccsds_counter.get_and_increment(), 0);
+        assert_eq!(ccsds_counter.get_and_increment(), 1);
+        assert_eq!(ccsds_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_ccsds_counter_overflow() {
+        let ccsds_counter = SequenceCounterCcsdsSimple::default();
+        for _ in 0..MAX_SEQ_COUNT.value() + 1 {
+            ccsds_counter.increment();
+        }
+        assert_eq!(ccsds_counter.get(), 0);
+    }
+
+    fn common_counter_test(seq_counter: &mut impl SequenceCounter) {
+        assert_eq!(seq_counter.get().into(), 0);
+        assert_eq!(seq_counter.get_and_increment().into(), 0);
+        assert_eq!(seq_counter.get_and_increment().into(), 1);
+        assert_eq!(seq_counter.get().into(), 2);
+        seq_counter.increment_mut();
+        assert_eq!(seq_counter.get().into(), 3);
+        assert_eq!(seq_counter.get_and_increment_mut().into(), 3);
+        assert_eq!(seq_counter.get().into(), 4);
+    }
+
+    #[test]
+    fn test_atomic_counter_u8() {
+        let mut sync_u8_counter = AtomicU8::new(0);
+        common_counter_test(&mut sync_u8_counter);
+    }
+
+    #[test]
+    fn test_atomic_counter_u16() {
+        let mut sync_u16_counter = AtomicU16::new(0);
+        common_counter_test(&mut sync_u16_counter);
+    }
+
+    #[test]
+    fn test_atomic_counter_u32() {
+        let mut sync_u32_counter = AtomicU32::new(0);
+        common_counter_test(&mut sync_u32_counter);
+    }
+
+    #[test]
+    fn test_atomic_counter_u64() {
+        let mut sync_u64_counter = AtomicU64::new(0);
+        common_counter_test(&mut sync_u64_counter);
+    }
+
+    #[test]
+    fn test_portable_atomic_counter_u8() {
+        let mut sync_u8_counter = portable_atomic::AtomicU8::new(0);
+        common_counter_test(&mut sync_u8_counter);
+    }
+
+    #[test]
+    fn test_portable_atomic_counter_u16() {
+        let mut sync_u16_counter = portable_atomic::AtomicU16::new(0);
+        common_counter_test(&mut sync_u16_counter);
+    }
+
+    #[test]
+    fn test_portable_atomic_counter_u32() {
+        let mut sync_u32_counter = portable_atomic::AtomicU32::new(0);
+        common_counter_test(&mut sync_u32_counter);
+    }
+
+    #[test]
+    fn test_portable_atomic_counter_u64() {
+        let mut sync_u64_counter = portable_atomic::AtomicU64::new(0);
+        common_counter_test(&mut sync_u64_counter);
+    }
+
+    fn common_overflow_test_u8(seq_counter: &impl SequenceCounter) {
+        for _ in 0..u8::MAX as u16 + 1 {
+            seq_counter.increment();
+        }
+        assert_eq!(seq_counter.get().into(), 0);
+    }
+
+    #[test]
+    fn test_atomic_u8_counter_overflow() {
+        let sync_u8_counter = AtomicU8::new(0);
+        common_overflow_test_u8(&sync_u8_counter);
+    }
+
+    #[test]
+    fn test_portable_atomic_u8_counter_overflow() {
+        let sync_u8_counter = portable_atomic::AtomicU8::new(0);
+        common_overflow_test_u8(&sync_u8_counter);
+    }
+
+    #[test]
+    fn test_atomic_ref_counters_overflow_custom_max_val() {
+        let sync_u8_counter = SequenceCounterSyncCustomWrapU8::new(128);
+        for _ in 0..129 {
+            sync_u8_counter.increment();
+        }
+        assert_eq!(sync_u8_counter.get(), 0);
+    }
+}

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")]
+#[cfg(all(feature = "alloc", feature = "chrono"))]
-use chrono::{
+pub use alloc_mod_chrono::*;
-    format::{DelayedFormat, StrftimeItems},
-    DateTime, Utc,
-};
 
 /// 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(all(feature = "alloc", feature = "chrono"))]
-#[cfg(feature = "alloc")]
+pub mod alloc_mod_chrono {
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+    use super::*;
-pub fn generate_time_code_a(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
+    use chrono::{
-    date.format(FMT_STR_CODE_A_WITH_SIZE.0)
+        format::{DelayedFormat, StrftimeItems},
-}
+        DateTime, Utc,
+    };
 
-/// Generates a time code formatter using the [FMT_STR_CODE_A_TERMINATED_WITH_SIZE] format.
+    /// Generates a time code formatter using the [FMT_STR_CODE_A_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
+    pub fn generate_time_code_a(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+        date.format(FMT_STR_CODE_A_WITH_SIZE.0)
-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_WITH_SIZE] format.
+    /// Generates a time code formatter using the [FMT_STR_CODE_A_TERMINATED_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
+    pub fn generate_time_code_a_terminated(
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+        date: &DateTime<Utc>,
-pub fn generate_time_code_b(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
+    ) -> DelayedFormat<StrftimeItems<'static>> {
-    date.format(FMT_STR_CODE_B_WITH_SIZE.0)
+        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.
+    /// Generates a time code formatter using the [FMT_STR_CODE_B_WITH_SIZE] format.
-#[cfg(feature = "alloc")]
+    pub fn generate_time_code_b(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
-#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+        date.format(FMT_STR_CODE_B_WITH_SIZE.0)
-pub fn generate_time_code_b_terminated(
+    }
-    date: &DateTime<Utc>,
+
-) -> DelayedFormat<StrftimeItems<'static>> {
+    /// Generates a time code formatter using the [FMT_STR_CODE_B_TERMINATED_WITH_SIZE] format.
-    date.format(FMT_STR_CODE_B_TERMINATED_WITH_SIZE.0)
+    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() {
+    fn test_ascii_timestamp_a_unterminated_epoch() {
-        let date = Utc::now();
+        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() {
+    fn test_ascii_timestamp_b_unterminated_epoch() {
-        let date = Utc::now();
+        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

@@ -1,11 +1,10 @@
 //! CCSDS Time Code Formats according to [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 use crate::ByteConversionError;
-use chrono::{DateTime, LocalResult, TimeZone, Utc};
+#[cfg(feature = "chrono")]
+use chrono::{TimeZone, Utc};
 use core::cmp::Ordering;
-use core::fmt::{Display, Formatter};
 use core::ops::{Add, AddAssign, Sub};
 use core::time::Duration;
-use core::u8;
 
 #[allow(unused_imports)]
 #[cfg(not(feature = "std"))]
@@ -13,8 +12,7 @@ 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")]
@@ -27,10 +25,12 @@ 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,
@@ -38,16 +38,16 @@ 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 == CcsdsTimeCode::CucCcsdsEpoch as u8 => Ok(CcsdsTimeCode::CucCcsdsEpoch),
-            x if x == CcsdsTimeCodes::CucAgencyEpoch as u8 => Ok(CcsdsTimeCodes::CucAgencyEpoch),
+            x if x == CcsdsTimeCode::CucAgencyEpoch as u8 => Ok(CcsdsTimeCode::CucAgencyEpoch),
-            x if x == CcsdsTimeCodes::Cds as u8 => Ok(CcsdsTimeCodes::Cds),
+            x if x == CcsdsTimeCode::Cds as u8 => Ok(CcsdsTimeCode::Cds),
-            x if x == CcsdsTimeCodes::Ccs as u8 => Ok(CcsdsTimeCodes::Ccs),
+            x if x == CcsdsTimeCode::Ccs as u8 => Ok(CcsdsTimeCode::Ccs),
-            x if x == CcsdsTimeCodes::AgencyDefined as u8 => Ok(CcsdsTimeCodes::AgencyDefined),
+            x if x == CcsdsTimeCode::AgencyDefined as u8 => Ok(CcsdsTimeCode::AgencyDefined),
             _ => Err(()),
         }
     }
@@ -55,76 +55,35 @@ 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)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[error("date before ccsds epoch: {0:?}")]
+pub struct DateBeforeCcsdsEpochError(UnixTime);
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[non_exhaustive]
 pub enum TimestampError {
-    InvalidTimeCode { expected: CcsdsTimeCodes, found: u8 },
+    #[error("invalid time code, expected {expected:?}, found {found}")]
-    ByteConversion(ByteConversionError),
+    InvalidTimeCode { expected: CcsdsTimeCode, found: u8 },
-    Cds(cds::CdsError),
+    #[error("time stamp: byte conversion error: {0}")]
-    Cuc(cuc::CucError),
+    ByteConversion(#[from] ByteConversionError),
-    DateBeforeCcsdsEpoch(DateTime<Utc>),
+    #[error("CDS error: {0}")]
+    Cds(#[from] cds::CdsError),
+    #[error("CUC error: {0}")]
+    Cuc(#[from] cuc::CucError),
+    #[error("custom epoch not supported")]
     CustomEpochNotSupported,
 }
 
-impl Display for TimestampError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            TimestampError::InvalidTimeCode { expected, found } => {
-                write!(
-                    f,
-                    "invalid raw time code value {found} for time code {expected:?}"
-                )
-            }
-            TimestampError::Cds(e) => {
-                write!(f, "cds error: {e}")
-            }
-            TimestampError::Cuc(e) => {
-                write!(f, "cuc error: {e}")
-            }
-            TimestampError::ByteConversion(e) => {
-                write!(f, "time stamp: {e}")
-            }
-            TimestampError::DateBeforeCcsdsEpoch(e) => {
-                write!(f, "datetime with date before ccsds epoch: {e}")
-            }
-            TimestampError::CustomEpochNotSupported => {
-                write!(f, "custom epochs are not supported")
-            }
-        }
-    }
-}
-
 #[cfg(feature = "std")]
-impl Error for TimestampError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        match self {
-            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")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 pub mod std_mod {
     use crate::time::TimestampError;
     use std::time::SystemTimeError;
@@ -132,7 +91,7 @@ pub mod std_mod {
 
     #[derive(Debug, Clone, Error)]
     pub enum StdTimestampError {
-        #[error("system time error: {0}")]
+        #[error("system time error: {0:?}")]
         SystemTime(#[from] SystemTimeError),
         #[error("timestamp error: {0}")]
         Timestamp(#[from] TimestampError),
@@ -140,7 +99,6 @@ pub mod std_mod {
 }
 
 #[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
 pub fn seconds_since_epoch() -> f64 {
     SystemTime::now()
         .duration_since(SystemTime::UNIX_EPOCH)
@@ -152,6 +110,7 @@ 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
 }
@@ -160,22 +119,24 @@ 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())
 }
@@ -196,7 +157,6 @@ pub trait TimeWriter {
     fn write_to_bytes(&self, bytes: &mut [u8]) -> Result<usize, TimestampError>;
 
     #[cfg(feature = "alloc")]
-    #[cfg_attr(doc_cfg, doc(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)?;
@@ -204,16 +164,15 @@ pub trait TimeWriter {
     }
 }
 
-pub trait TimeReader {
+pub trait TimeReader: Sized {
-    fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError>
+    fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError>;
-    where
-        Self: Sized;
 }
 
 /// 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;
 
@@ -222,125 +181,203 @@ 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 unix_secs(&self) -> i64;
-    fn subsecond_millis(&self) -> u16;
+    fn subsec_nanos(&self) -> u32;
-    fn unix_stamp(&self) -> UnixTimestamp {
+
-        UnixTimestamp::const_new(self.unix_seconds(), self.subsecond_millis())
+    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.
+/// 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 {
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
-    pub unix_seconds: i64,
+pub struct UnixTime {
-    subsecond_millis: u16,
+    secs: i64,
+    subsec_nanos: u32,
 }
 
-impl UnixTimestamp {
+impl UnixTime {
-    /// Returns [None] if the subsecond millisecond value is larger than 999.
+    /// The UNIX epoch time: 1970-01-01T00:00:00+00:00 UTC.
-    pub fn new(unix_seconds: i64, subsec_millis: u16) -> Option<Self> {
+    pub const EPOCH: Self = Self {
-        if subsec_millis > 999 {
+        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.
+    /// Returns [None] if the subsecond millisecond value is invalid (larger than fraction of a
-    pub const fn const_new(unix_seconds: i64, subsecond_millis: u16) -> Self {
+    /// second)
-        if subsecond_millis > 999 {
+    pub fn new_subsec_millis_checked(unix_seconds: i64, subsec_millis: u16) -> Option<Self> {
-            panic!("subsec milliseconds exceeds 999");
+        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");
         }
         Self {
-            unix_seconds,
+            secs: unix_seconds,
-            subsecond_millis,
+            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,
+            secs: unix_seconds,
-            subsecond_millis: 0,
+            subsec_nanos: subsecond_millis as u32 * 1_000_000,
         }
     }
 
-    pub fn subsecond_millis(&self) -> u16 {
+    pub fn new_only_secs(unix_seconds: i64) -> Self {
-        self.subsecond_millis
+        Self {
-    }
+            secs: unix_seconds,
-
+            subsec_nanos: 0,
-    #[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))
     }
 
     #[inline]
-    pub fn unix_seconds_f64(&self) -> f64 {
+    pub fn subsec_millis(&self) -> u16 {
-        self.unix_seconds as f64 + (self.subsecond_millis as f64 / 1000.0)
+        (self.subsec_nanos / 1_000_000) as u16
     }
 
-    pub fn as_date_time(&self) -> LocalResult<DateTime<Utc>> {
+    pub fn subsec_nanos(&self) -> u32 {
-        Utc.timestamp_opt(
+        self.subsec_nanos
-            self.unix_seconds,
+    }
-            self.subsecond_millis as u32 * 10_u32.pow(6),
+
-        )
+    #[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 difference_in_millis(&self, other: &UnixTimestamp) -> i64 {
+    pub fn diff_in_millis(&self, other: &UnixTime) -> Option<i64> {
-        let seconds_difference = self.unix_seconds - other.unix_seconds;
+        let seconds_difference = self.secs.checked_sub(other.secs)?;
         // Convert seconds difference to milliseconds
-        let milliseconds_difference = seconds_difference * 1000;
+        let milliseconds_difference = seconds_difference.checked_mul(1000)?;
 
         // Calculate the difference in subsecond milliseconds directly
-        let subsecond_difference = self.subsecond_millis as i64 - other.subsecond_millis as i64;
+        let subsecond_difference_nanos = self.subsec_nanos as i64 - other.subsec_nanos as i64;
 
         // Combine the differences
-        milliseconds_difference + subsecond_difference
+        Some(milliseconds_difference + (subsecond_difference_nanos / 1_000_000))
     }
 }
 
-impl From<DateTime<Utc>> for UnixTimestamp {
+#[cfg(feature = "chrono")]
-    fn from(value: DateTime<Utc>) -> Self {
+impl From<chrono::DateTime<chrono::Utc>> for UnixTime {
-        Self::const_new(value.timestamp(), value.timestamp_subsec_millis() as u16)
+    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 UnixTimestamp {
+impl Ord for UnixTime {
     fn cmp(&self, other: &Self) -> Ordering {
         if self == other {
             return Ordering::Equal;
         }
-        match self.unix_seconds.cmp(&other.unix_seconds) {
+        match self.secs.cmp(&other.secs) {
             Ordering::Less => return Ordering::Less,
             Ordering::Greater => return Ordering::Greater,
             _ => (),
         }
 
-        match self.subsecond_millis().cmp(&other.subsecond_millis()) {
+        match self.subsec_millis().cmp(&other.subsec_millis()) {
             Ordering::Less => {
-                return if self.unix_seconds < 0 {
+                return if self.secs < 0 {
                     Ordering::Greater
                 } else {
                     Ordering::Less
                 }
             }
             Ordering::Greater => {
-                return if self.unix_seconds < 0 {
+                return if self.secs < 0 {
                     Ordering::Less
                 } else {
                     Ordering::Greater
@@ -360,12 +397,12 @@ pub struct StampDiff {
     pub duration_absolute: Duration,
 }
 
-impl Sub for UnixTimestamp {
+impl Sub for UnixTime {
-    type Output = StampDiff;
+    type Output = Option<StampDiff>;
 
     fn sub(self, rhs: Self) -> Self::Output {
-        let difference = self.difference_in_millis(&rhs);
+        let difference = self.diff_in_millis(&rhs)?;
-        if difference < 0 {
+        Some(if difference < 0 {
             StampDiff {
                 positive_duration: false,
                 duration_absolute: Duration::from_millis(-difference as u64),
@@ -375,16 +412,13 @@ impl Sub for UnixTimestamp {
                 positive_duration: true,
                 duration_absolute: Duration::from_millis(difference as u64),
             }
-        }
+        })
     }
 }
 
-fn get_new_stamp_after_addition(
+fn get_new_stamp_after_addition(current_stamp: &UnixTime, duration: Duration) -> UnixTime {
-    current_stamp: &UnixTimestamp,
+    let mut new_subsec_nanos = current_stamp.subsec_nanos() + duration.subsec_nanos();
-    duration: Duration,
+    let mut new_unix_seconds = current_stamp.secs;
-) -> UnixTimestamp {
-    let mut new_subsec_millis = current_stamp.subsecond_millis() + duration.subsec_millis() as u16;
-    let mut new_unix_seconds = current_stamp.unix_seconds;
     let mut increment_seconds = |value: u32| {
         if new_unix_seconds < 0 {
             new_unix_seconds = new_unix_seconds
@@ -396,8 +430,8 @@ fn get_new_stamp_after_addition(
                 .expect("new unix seconds would exceed i64::MAX");
         }
     };
-    if new_subsec_millis >= 1000 {
+    if new_subsec_nanos >= 1_000_000_000 {
-        new_subsec_millis -= 1000;
+        new_subsec_nanos -= 1_000_000_000;
         increment_seconds(1);
     }
     increment_seconds(
@@ -406,7 +440,7 @@ 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:
@@ -414,7 +448,7 @@ 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);
     }
@@ -425,7 +459,7 @@ 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 {
@@ -433,8 +467,8 @@ impl Add<Duration> for UnixTimestamp {
     }
 }
 
-impl Add<Duration> for &UnixTimestamp {
+impl Add<Duration> for &UnixTime {
-    type Output = UnixTimestamp;
+    type Output = UnixTime;
 
     fn add(self, duration: Duration) -> Self::Output {
         get_new_stamp_after_addition(self, duration)
@@ -445,10 +479,15 @@ impl Add<Duration> for &UnixTimestamp {
 mod tests {
     use alloc::string::ToString;
     use chrono::{Datelike, Timelike};
-    use std::format;
+    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() {
         assert_eq!(unix_to_ccsds_days(DAYS_CCSDS_TO_UNIX.into()), 0);
@@ -456,6 +495,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_get_current_time() {
         let sec_floats = seconds_since_epoch();
         assert!(sec_floats > 0.0);
@@ -470,6 +510,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_ccsds_epoch() {
         let now = SystemTime::now()
             .duration_since(SystemTime::UNIX_EPOCH)
@@ -484,28 +525,29 @@ mod tests {
 
     #[test]
     fn basic_unix_stamp_test() {
-        let stamp = UnixTimestamp::new_only_seconds(-200);
+        let stamp = UnixTime::new_only_secs(-200);
-        assert_eq!(stamp.unix_seconds, -200);
+        assert_eq!(stamp.secs, -200);
-        assert_eq!(stamp.subsecond_millis(), 0);
+        assert_eq!(stamp.subsec_millis(), 0);
-        let stamp = UnixTimestamp::new_only_seconds(250);
+        let stamp = UnixTime::new_only_secs(250);
-        assert_eq!(stamp.unix_seconds, 250);
+        assert_eq!(stamp.secs, 250);
-        assert_eq!(stamp.subsecond_millis(), 0);
+        assert_eq!(stamp.subsec_millis(), 0);
     }
 
     #[test]
     fn basic_float_unix_stamp_test() {
-        let stamp = UnixTimestamp::new(500, 600).unwrap();
+        let stamp = UnixTime::new_subsec_millis_checked(500, 600).unwrap();
-        assert_eq!(stamp.unix_seconds, 500);
+        assert_eq!(stamp.secs, 500);
-        let subsec_millis = stamp.subsecond_millis();
+        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 stamp0 = UnixTime::new_only_secs(5);
-        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
+        let stamp1 = UnixTime::new_subsec_millis_checked(5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        let stamp2 = UnixTime::new_only_secs(6);
         assert!(stamp1 > stamp0);
         assert!(stamp2 > stamp0);
         assert!(stamp2 > stamp1);
@@ -513,9 +555,9 @@ mod tests {
 
     #[test]
     fn test_ord_smaller() {
-        let stamp0 = UnixTimestamp::new_only_seconds(5);
+        let stamp0 = UnixTime::new_only_secs(5);
-        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
+        let stamp1 = UnixTime::new_subsec_millis_checked(5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        let stamp2 = UnixTime::new_only_secs(6);
         assert!(stamp0 < stamp1);
         assert!(stamp0 < stamp2);
         assert!(stamp1 < stamp2);
@@ -523,9 +565,9 @@ mod tests {
 
     #[test]
     fn test_ord_larger_neg_numbers() {
-        let stamp0 = UnixTimestamp::new_only_seconds(-5);
+        let stamp0 = UnixTime::new_only_secs(-5);
-        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
+        let stamp1 = UnixTime::new_subsec_millis_checked(-5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        let stamp2 = UnixTime::new_only_secs(-6);
         assert!(stamp0 > stamp1);
         assert!(stamp0 > stamp2);
         assert!(stamp1 > stamp2);
@@ -535,9 +577,9 @@ mod tests {
 
     #[test]
     fn test_ord_smaller_neg_numbers() {
-        let stamp0 = UnixTimestamp::new_only_seconds(-5);
+        let stamp0 = UnixTime::new_only_secs(-5);
-        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
+        let stamp1 = UnixTime::new_subsec_millis_checked(-5, 500).unwrap();
-        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        let stamp2 = UnixTime::new_only_secs(-6);
         assert!(stamp2 < stamp1);
         assert!(stamp2 < stamp0);
         assert!(stamp1 < stamp0);
@@ -548,8 +590,8 @@ mod tests {
     #[allow(clippy::nonminimal_bool)]
     #[test]
     fn test_eq() {
-        let stamp0 = UnixTimestamp::new(5, 0).unwrap();
+        let stamp0 = UnixTime::new(5, 0);
-        let stamp1 = UnixTimestamp::new_only_seconds(5);
+        let stamp1 = UnixTime::new_only_secs(5);
         assert_eq!(stamp0, stamp1);
         assert!(stamp0 <= stamp1);
         assert!(stamp0 >= stamp1);
@@ -559,27 +601,27 @@ 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_eq!(stamp0.as_secs(), 6);
-        assert_eq!(stamp0.subsecond_millis(), 0);
+        assert_eq!(stamp0.subsec_millis(), 0);
         let stamp1 = stamp0 + Duration::from_millis(500);
-        assert_eq!(stamp1.unix_seconds, 6);
+        assert_eq!(stamp1.secs, 6);
-        assert_eq!(stamp1.subsecond_millis(), 500);
+        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_eq!(stamp1.secs, 23);
-        assert_eq!(stamp1.subsecond_millis(), 0);
+        assert_eq!(stamp1.subsec_millis(), 0);
     }
 
     #[test]
     fn test_as_dt() {
-        let stamp = UnixTimestamp::new_only_seconds(0);
+        let stamp = UnixTime::new_only_secs(0);
-        let dt = stamp.as_date_time().unwrap();
+        let dt = stamp.chrono_date_time().unwrap();
         assert_eq!(dt.year(), 1970);
         assert_eq!(dt.month(), 1);
         assert_eq!(dt.day(), 1);
@@ -589,62 +631,85 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_from_now() {
-        let stamp_now = UnixTimestamp::from_now().unwrap();
+        let stamp_now = UnixTime::now().unwrap();
-        let dt_now = stamp_now.as_date_time().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 = UnixTimestamp::new(2, 0).unwrap();
+        let stamp_later = UnixTime::new(2, 0);
         let StampDiff {
             positive_duration,
             duration_absolute,
-        } = stamp_later - UnixTimestamp::new(1, 0).unwrap();
+        } = (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 = UnixTimestamp::new(3, 800).unwrap();
+        let stamp_later = UnixTime::new(3, 800 * 1_000_000);
-        let stamp_earlier = UnixTimestamp::new(1, 900).unwrap();
+        let stamp_earlier = UnixTime::new_subsec_millis_checked(1, 900).unwrap();
         let StampDiff {
             positive_duration,
             duration_absolute,
-        } = stamp_later - stamp_earlier;
+        } = (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 = UnixTimestamp::new(3, 800).unwrap();
+        let stamp_later = UnixTime::new_subsec_millis_checked(3, 800).unwrap();
-        let stamp_earlier = UnixTimestamp::new(1, 900).unwrap();
+        let stamp_earlier = UnixTime::new_subsec_millis_checked(1, 900).unwrap();
         let StampDiff {
             positive_duration,
             duration_absolute,
-        } = stamp_earlier - stamp_later;
+        } = (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_eq!(stamp0.secs, 2);
-        assert_eq!(stamp0.subsecond_millis(), 0);
+        assert_eq!(stamp0.subsec_millis(), 0);
         stamp0 += Duration::from_millis(1100);
-        assert_eq!(stamp0.unix_seconds, 3);
+        assert_eq!(stamp0.secs, 3);
-        assert_eq!(stamp0.subsecond_millis(), 100);
+        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}"));
+        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/uslp/mod.rs

@@ -0,0 +1,948 @@
+/// # Support of the CCSDS Unified Space Data Link Protocol (USLP)
+use crate::{crc::CRC_CCITT_FALSE, ByteConversionError};
+
+/// Only this version is supported by the library
+pub const USLP_VERSION_NUMBER: u8 = 0b1100;
+
+/// Identifies the association of the data contained in the transfer frame.
+#[derive(Debug, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
+#[repr(u8)]
+pub enum SourceOrDestField {
+    /// SCID refers to the source of the transfer frame.
+    Source = 0,
+    /// SCID refers to the destination of the transfer frame.
+    Dest = 1,
+}
+
+#[derive(Debug, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
+#[repr(u8)]
+pub enum BypassSequenceControlFlag {
+    /// Acceptance of this frame on the receiving end is subject to normal frame acceptance
+    /// checks of FARM.
+    SequenceControlledQoS = 0,
+    /// Frame Acceptance Checks of FARM by the receiving end shall be bypassed.
+    ExpeditedQoS = 1,
+}
+
+#[derive(
+    Debug, Copy, Clone, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive,
+)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum ProtocolControlCommandFlag {
+    TfdfContainsUserData = 0,
+    TfdfContainsProtocolInfo = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+pub enum UslpError {
+    #[error("byte conversion error: {0}")]
+    ByteConversion(#[from] ByteConversionError),
+    #[error("header is truncated, which is not supported")]
+    HeaderIsTruncated,
+    #[error("invalid protocol id: {0}")]
+    InvalidProtocolId(u8),
+    #[error("invalid construction rule: {0}")]
+    InvalidConstructionRule(u8),
+    #[error("invalid version number: {0}")]
+    InvalidVersionNumber(u8),
+    #[error("invalid virtual channel ID: {0}")]
+    InvalidVcId(u8),
+    #[error("invalid MAP ID: {0}")]
+    InvalidMapId(u8),
+    #[error("checksum failure")]
+    ChecksumFailure(u16),
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct InvalidValueForLen {
+    value: u64,
+    len: u8,
+}
+
+#[derive(Debug, Copy, Clone, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct PrimaryHeader {
+    pub spacecraft_id: u16,
+    pub source_or_dest_field: SourceOrDestField,
+    pub vc_id: u8,
+    pub map_id: u8,
+    frame_len_field: u16,
+    pub sequence_control_flag: BypassSequenceControlFlag,
+    pub protocol_control_command_flag: ProtocolControlCommandFlag,
+    pub ocf_flag: bool,
+    vc_frame_count_len: u8,
+    vc_frame_count: u64,
+}
+
+impl PrimaryHeader {
+    pub fn new(
+        spacecraft_id: u16,
+        source_or_dest_field: SourceOrDestField,
+        vc_id: u8,
+        map_id: u8,
+        frame_len: u16,
+    ) -> Result<Self, UslpError> {
+        if vc_id > 0b111111 {
+            return Err(UslpError::InvalidVcId(vc_id));
+        }
+        if map_id > 0b1111 {
+            return Err(UslpError::InvalidMapId(map_id));
+        }
+        Ok(Self {
+            spacecraft_id,
+            source_or_dest_field,
+            vc_id,
+            map_id,
+            frame_len_field: frame_len.saturating_sub(1),
+            sequence_control_flag: BypassSequenceControlFlag::SequenceControlledQoS,
+            protocol_control_command_flag: ProtocolControlCommandFlag::TfdfContainsUserData,
+            ocf_flag: false,
+            vc_frame_count_len: 0,
+            vc_frame_count: 0,
+        })
+    }
+
+    pub fn set_vc_frame_count(
+        &mut self,
+        count_len: u8,
+        count: u64,
+    ) -> Result<(), InvalidValueForLen> {
+        if count > 2_u64.pow(count_len as u32 * 8) - 1 {
+            return Err(InvalidValueForLen {
+                value: count,
+                len: count_len,
+            });
+        }
+        self.vc_frame_count_len = count_len;
+        self.vc_frame_count = count;
+        Ok(())
+    }
+
+    #[inline]
+    pub fn vc_frame_count(&self) -> u64 {
+        self.vc_frame_count
+    }
+
+    #[inline]
+    pub fn vc_frame_count_len(&self) -> u8 {
+        self.vc_frame_count_len
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<Self, UslpError> {
+        if buf.len() < 4 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 4,
+            }
+            .into());
+        }
+        // Can only deal with regular frames for now.
+        if (buf[3] & 0b1) == 1 {
+            return Err(UslpError::HeaderIsTruncated);
+        }
+        // We could check this above, but this is a better error for the case where the user
+        // tries to read a truncated frame.
+        if buf.len() < 7 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 7,
+            }
+            .into());
+        }
+        let version_number = (buf[0] >> 4) & 0b1111;
+        if version_number != USLP_VERSION_NUMBER {
+            return Err(UslpError::InvalidVersionNumber(version_number));
+        }
+        let source_or_dest_field = match (buf[2] >> 3) & 1 {
+            0 => SourceOrDestField::Source,
+            1 => SourceOrDestField::Dest,
+            _ => unreachable!(),
+        };
+        let vc_frame_count_len = buf[6] & 0b111;
+        if buf.len() < 7 + vc_frame_count_len as usize {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 7 + vc_frame_count_len as usize,
+            }
+            .into());
+        }
+        let vc_frame_count = match vc_frame_count_len {
+            1 => buf[7] as u64,
+            2 => u16::from_be_bytes(buf[7..9].try_into().unwrap()) as u64,
+            4 => u32::from_be_bytes(buf[7..11].try_into().unwrap()) as u64,
+            len => {
+                let mut vcf_count = 0u64;
+                let mut end = len;
+                for byte in buf[7..7 + len as usize].iter() {
+                    vcf_count |= (*byte as u64) << ((end - 1) * 8);
+                    end -= 1;
+                }
+                vcf_count
+            }
+        };
+        Ok(Self {
+            spacecraft_id: (((buf[0] as u16) & 0b1111) << 12)
+                | ((buf[1] as u16) << 4)
+                | ((buf[2] as u16) >> 4) & 0b1111,
+            source_or_dest_field,
+            vc_id: ((buf[2] & 0b111) << 3) | (buf[3] >> 5) & 0b111,
+            map_id: (buf[3] >> 1) & 0b1111,
+            frame_len_field: ((buf[4] as u16) << 8) | buf[5] as u16,
+            sequence_control_flag: ((buf[6] >> 7) & 0b1).try_into().unwrap(),
+            protocol_control_command_flag: ((buf[6] >> 6) & 0b1).try_into().unwrap(),
+            ocf_flag: ((buf[6] >> 3) & 0b1) != 0,
+            vc_frame_count_len,
+            vc_frame_count,
+        })
+    }
+
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.len_header() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_header(),
+            });
+        }
+        buf[0] = (USLP_VERSION_NUMBER << 4) | ((self.spacecraft_id >> 12) as u8) & 0b1111;
+        buf[1] = (self.spacecraft_id >> 4) as u8;
+        buf[2] = (((self.spacecraft_id & 0b1111) as u8) << 4)
+            | ((self.source_or_dest_field as u8) << 3)
+            | (self.vc_id >> 3) & 0b111;
+        buf[3] = ((self.vc_id & 0b111) << 5) | (self.map_id << 1);
+        buf[4..6].copy_from_slice(&self.frame_len_field.to_be_bytes());
+        buf[6] = ((self.sequence_control_flag as u8) << 7)
+            | ((self.protocol_control_command_flag as u8) << 6)
+            | ((self.ocf_flag as u8) << 3)
+            | self.vc_frame_count_len;
+        let mut packet_idx = 7;
+        for idx in (0..self.vc_frame_count_len).rev() {
+            buf[packet_idx] = ((self.vc_frame_count >> (idx * 8)) & 0xff) as u8;
+            packet_idx += 1;
+        }
+        Ok(self.len_header())
+    }
+
+    #[inline(always)]
+    pub fn set_frame_len(&mut self, frame_len: usize) {
+        // 4.1.2.7.2
+        // The field contains a length count C that equals one fewer than the total octets
+        // in the transfer frame.
+        self.frame_len_field = frame_len.saturating_sub(1) as u16;
+    }
+
+    #[inline(always)]
+    pub fn len_header(&self) -> usize {
+        7 + self.vc_frame_count_len as usize
+    }
+
+    #[inline(always)]
+    pub fn len_frame(&self) -> usize {
+        // 4.1.2.7.2
+        // The field contains a length count C that equals one fewer than the total octets
+        // in the transfer frame.
+        self.frame_len_field as usize + 1
+    }
+}
+
+/// Custom implementation which skips the check whether the VC frame count length field is equal.
+/// Only the actual VC count value is compared.
+impl PartialEq for PrimaryHeader {
+    fn eq(&self, other: &Self) -> bool {
+        self.spacecraft_id == other.spacecraft_id
+            && self.source_or_dest_field == other.source_or_dest_field
+            && self.vc_id == other.vc_id
+            && self.map_id == other.map_id
+            && self.frame_len_field == other.frame_len_field
+            && self.sequence_control_flag == other.sequence_control_flag
+            && self.protocol_control_command_flag == other.protocol_control_command_flag
+            && self.ocf_flag == other.ocf_flag
+            && self.vc_frame_count == other.vc_frame_count
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u5, exhaustive = false)]
+#[repr(u8)]
+#[non_exhaustive]
+pub enum UslpProtocolId {
+    SpacePacketsOrEncapsulation = 0b00000,
+    /// COP-1 control commands within the TFDZ.
+    Cop1ControlCommands = 0b00001,
+    /// COP-P control commands within the TFDZ.
+    CopPControlCommands = 0b00010,
+    /// SDLS control commands within the TFDZ.
+    Sdls = 0b00011,
+    UserDefinedOctetStream = 0b00100,
+    /// Proximity-1 Supervisory Protocol Data Units (SPDUs) within the TFDZ.
+    Spdu = 0b00111,
+    /// Entire fixed-length TFDZ contains idle data.
+    Idle = 0b11111,
+}
+
+#[derive(Debug, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u3, exhaustive = true)]
+#[repr(u8)]
+pub enum ConstructionRule {
+    /// Indicated fixed-length TFDZ whose contents are CCSDS packets concatenated together, which
+    /// span transfer frame boundaries. The First Header Pointer (FHP) is required for packet
+    /// extraction.
+    PacketSpanningMultipleFrames = 0b000,
+    StartOfMapaSduOrVcaSdu = 0b001,
+    ContinuingPortionOfMapaSdu = 0b010,
+    OctetStream = 0b011,
+    StartingSegment = 0b100,
+    ContinuingSegment = 0b101,
+    LastSegment = 0b110,
+    NoSegmentation = 0b111,
+}
+
+impl ConstructionRule {
+    pub const fn applicable_to_fixed_len_tfdz(&self) -> bool {
+        match self {
+            ConstructionRule::PacketSpanningMultipleFrames => true,
+            ConstructionRule::StartOfMapaSduOrVcaSdu => true,
+            ConstructionRule::ContinuingPortionOfMapaSdu => true,
+            ConstructionRule::OctetStream => false,
+            ConstructionRule::StartingSegment => false,
+            ConstructionRule::ContinuingSegment => false,
+            ConstructionRule::LastSegment => false,
+            ConstructionRule::NoSegmentation => false,
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct TransferFrameDataFieldHeader {
+    /// Construction rule for the TFDZ.
+    construction_rule: ConstructionRule,
+    uslp_protocol_id: UslpProtocolId,
+    /// First header or last valid octet pointer. Only present if the constuction rule indicated
+    /// a fixed-length TFDZ.
+    fhp_or_lvo: Option<u16>,
+}
+
+impl TransferFrameDataFieldHeader {
+    #[inline]
+    pub const fn len_header(&self) -> usize {
+        if self.construction_rule.applicable_to_fixed_len_tfdz() {
+            3
+        } else {
+            1
+        }
+    }
+
+    #[inline]
+    pub const fn construction_rule(&self) -> ConstructionRule {
+        self.construction_rule
+    }
+
+    #[inline]
+    pub const fn uslp_protocol_id(&self) -> UslpProtocolId {
+        self.uslp_protocol_id
+    }
+
+    #[inline]
+    pub const fn fhp_or_lvo(&self) -> Option<u16> {
+        self.fhp_or_lvo
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<Self, UslpError> {
+        if buf.is_empty() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: 0,
+                expected: 1,
+            }
+            .into());
+        }
+        let construction_rule = ConstructionRule::try_from((buf[0] >> 5) & 0b111)
+            .map_err(|e| UslpError::InvalidConstructionRule(e.number))?;
+        let mut fhp_or_lvo = None;
+        if construction_rule.applicable_to_fixed_len_tfdz() {
+            if buf.len() < 3 {
+                return Err(ByteConversionError::FromSliceTooSmall {
+                    found: buf.len(),
+                    expected: 3,
+                }
+                .into());
+            }
+            fhp_or_lvo = Some(u16::from_be_bytes(buf[1..3].try_into().unwrap()));
+        }
+        Ok(Self {
+            construction_rule,
+            uslp_protocol_id: UslpProtocolId::try_from(buf[0] & 0b11111)
+                .map_err(|e| UslpError::InvalidProtocolId(e.number))?,
+            fhp_or_lvo,
+        })
+    }
+}
+
+/// Simple USLP transfer frame reader.
+///
+/// Currently, only insert zone lengths of 0 are supported.
+#[derive(Debug)]
+pub struct TransferFrameReader<'buf> {
+    primary_header: PrimaryHeader,
+    data_field_header: TransferFrameDataFieldHeader,
+    data: &'buf [u8],
+    operational_control_field: Option<u32>,
+}
+
+impl<'buf> TransferFrameReader<'buf> {
+    /// This function assumes an insert zone length of 0.
+    pub fn from_bytes(
+        buf: &'buf [u8],
+        has_fecf: bool,
+    ) -> Result<TransferFrameReader<'buf>, UslpError> {
+        let primary_header = PrimaryHeader::from_bytes(buf)?;
+        if primary_header.len_frame() > buf.len() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                expected: primary_header.len_frame(),
+                found: buf.len(),
+            }
+            .into());
+        }
+        let data_field_header =
+            TransferFrameDataFieldHeader::from_bytes(&buf[primary_header.len_header()..])?;
+        let data_idx = primary_header.len_header() + data_field_header.len_header();
+        let frame_len = primary_header.len_frame();
+        let mut operational_control_field = None;
+        let mut data_len = frame_len - data_idx;
+        if has_fecf {
+            data_len -= 2;
+        }
+        if primary_header.ocf_flag {
+            data_len -= 4;
+            operational_control_field = Some(u32::from_be_bytes(
+                buf[data_idx + data_len..data_idx + data_len + 4]
+                    .try_into()
+                    .unwrap(),
+            ));
+        }
+        let data_end = data_idx + data_len;
+        if has_fecf {
+            let mut digest = CRC_CCITT_FALSE.digest();
+            digest.update(&buf[0..frame_len]);
+            if digest.finalize() != 0 {
+                return Err(UslpError::ChecksumFailure(u16::from_be_bytes(
+                    buf[frame_len - 2..frame_len].try_into().unwrap(),
+                )));
+            }
+        }
+        Ok(Self {
+            primary_header,
+            data_field_header,
+            data: buf[data_idx..data_end].try_into().unwrap(),
+            operational_control_field,
+        })
+    }
+
+    #[inline]
+    pub fn len_frame(&self) -> usize {
+        self.primary_header.len_frame()
+    }
+
+    #[inline]
+    pub fn primary_header(&self) -> &PrimaryHeader {
+        &self.primary_header
+    }
+
+    #[inline]
+    pub fn data_field_header(&self) -> &TransferFrameDataFieldHeader {
+        &self.data_field_header
+    }
+
+    #[inline]
+    pub fn data(&self) -> &'buf [u8] {
+        self.data
+    }
+
+    #[inline]
+    pub fn operational_control_field(&self) -> &Option<u32> {
+        &self.operational_control_field
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn common_basic_check(buf: &[u8]) {
+        assert_eq!(buf[0] >> 4, USLP_VERSION_NUMBER);
+        // First four bits SCID.
+        assert_eq!(buf[0] & 0b1111, 0b1010);
+        // Next eight bits SCID.
+        assert_eq!(buf[1], 0b01011100);
+        // Last four bits SCID.
+        assert_eq!(buf[2] >> 4, 0b0011);
+        assert_eq!((buf[2] >> 3) & 0b1, SourceOrDestField::Dest as u8);
+        // First three bits VCID.
+        assert_eq!(buf[2] & 0b111, 0b110);
+        // Last three bits VCID.
+        assert_eq!(buf[3] >> 5, 0b101);
+        // MAP ID
+        assert_eq!((buf[3] >> 1) & 0b1111, 0b1010);
+        // End of primary header flag
+        assert_eq!(buf[3] & 0b1, 0);
+        assert_eq!(u16::from_be_bytes(buf[4..6].try_into().unwrap()), 0x2344);
+    }
+
+    #[test]
+    fn test_basic_0() {
+        let mut buf: [u8; 8] = [0; 8];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        // Virtual channel count 0.
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 7);
+        common_basic_check(&buf);
+        assert_eq!(primary_header.vc_frame_count_len(), 0);
+        assert_eq!(primary_header.vc_frame_count(), 0);
+        // Bypass / Sequence Control Flag.
+        assert_eq!(
+            (buf[6] >> 7) & 0b1,
+            BypassSequenceControlFlag::SequenceControlledQoS as u8
+        );
+        // Protocol Control Command Flag.
+        assert_eq!(
+            (buf[6] >> 6) & 0b1,
+            ProtocolControlCommandFlag::TfdfContainsUserData as u8
+        );
+        // OCF flag.
+        assert_eq!((buf[6] >> 3) & 0b1, false as u8);
+        // VCF count length.
+        assert_eq!(buf[6] & 0b111, 0);
+    }
+
+    #[test]
+    fn test_basic_1() {
+        let mut buf: [u8; 16] = [0; 16];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.sequence_control_flag = BypassSequenceControlFlag::ExpeditedQoS;
+        primary_header.protocol_control_command_flag =
+            ProtocolControlCommandFlag::TfdfContainsProtocolInfo;
+        primary_header.ocf_flag = true;
+        primary_header.set_vc_frame_count(4, 0x12345678).unwrap();
+        // Virtual channel count 4.
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 11);
+        assert_eq!(primary_header.vc_frame_count_len(), 4);
+        assert_eq!(primary_header.vc_frame_count(), 0x12345678);
+        common_basic_check(&buf);
+        // Bypass / Sequence Control Flag.
+        assert_eq!(
+            (buf[6] >> 7) & 0b1,
+            BypassSequenceControlFlag::ExpeditedQoS as u8
+        );
+        // Protocol Control Command Flag.
+        assert_eq!(
+            (buf[6] >> 6) & 0b1,
+            ProtocolControlCommandFlag::TfdfContainsProtocolInfo as u8
+        );
+        // OCF flag.
+        assert_eq!((buf[6] >> 3) & 0b1, true as u8);
+        // VCF count length.
+        assert_eq!(buf[6] & 0b111, 4);
+        assert_eq!(
+            u32::from_be_bytes(buf[7..11].try_into().unwrap()),
+            0x12345678
+        );
+    }
+
+    #[test]
+    fn test_vcf_count_len_two() {
+        let mut buf: [u8; 16] = [0; 16];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.set_vc_frame_count(2, 5).unwrap();
+        assert_eq!(primary_header.vc_frame_count_len(), 2);
+        assert_eq!(primary_header.vc_frame_count(), 5);
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 9);
+        assert_eq!(buf[6] & 0b111, 2);
+        assert_eq!(u16::from_be_bytes(buf[7..9].try_into().unwrap()), 5);
+
+        let primary_header = PrimaryHeader::from_bytes(&buf).unwrap();
+        assert_eq!(primary_header.vc_frame_count_len(), 2);
+        assert_eq!(primary_header.vc_frame_count(), 5);
+    }
+
+    #[test]
+    fn test_vcf_count_len_one() {
+        let mut buf: [u8; 16] = [0; 16];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.set_vc_frame_count(1, 255).unwrap();
+        assert_eq!(primary_header.vc_frame_count_len(), 1);
+        assert_eq!(primary_header.vc_frame_count(), 255);
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 8);
+        assert_eq!(buf[6] & 0b111, 1);
+        assert_eq!(buf[7], 255);
+
+        let primary_header = PrimaryHeader::from_bytes(&buf).unwrap();
+        assert_eq!(primary_header.vc_frame_count_len(), 1);
+        assert_eq!(primary_header.vc_frame_count(), 255);
+    }
+
+    #[test]
+    fn test_reading_0() {
+        let mut buf: [u8; 8] = [0; 8];
+        let primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 7);
+        let parsed_header = PrimaryHeader::from_bytes(&buf).unwrap();
+        assert_eq!(parsed_header, primary_header);
+    }
+
+    #[test]
+    fn test_reading_1() {
+        let mut buf: [u8; 16] = [0; 16];
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.sequence_control_flag = BypassSequenceControlFlag::ExpeditedQoS;
+        primary_header.protocol_control_command_flag =
+            ProtocolControlCommandFlag::TfdfContainsProtocolInfo;
+        primary_header.ocf_flag = true;
+        primary_header.set_vc_frame_count(4, 0x12345678).unwrap();
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 11);
+        let parsed_header = PrimaryHeader::from_bytes(&buf).unwrap();
+        assert_eq!(parsed_header, primary_header);
+    }
+
+    #[test]
+    fn test_invalid_vcid() {
+        let error = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b1101011,
+            0b1010,
+            0x2345,
+        );
+        assert!(error.is_err());
+        let error = error.unwrap_err();
+        matches!(error, UslpError::InvalidVcId(0b1101011));
+    }
+
+    #[test]
+    fn test_invalid_mapid() {
+        let error = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b10101,
+            0x2345,
+        );
+        assert!(error.is_err());
+        let error = error.unwrap_err();
+        matches!(error, UslpError::InvalidMapId(0b10101));
+    }
+
+    #[test]
+    fn test_invalid_vc_count() {
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        matches!(
+            primary_header.set_vc_frame_count(0, 1).unwrap_err(),
+            InvalidValueForLen { value: 1, len: 0 }
+        );
+        matches!(
+            primary_header.set_vc_frame_count(1, 256).unwrap_err(),
+            InvalidValueForLen { value: 256, len: 1 }
+        );
+    }
+
+    #[test]
+    fn test_frame_parser() {
+        let mut buf: [u8; 32] = [0; 32];
+        // Build a variable frame manually.
+        let mut primary_header =
+            PrimaryHeader::new(0x01, SourceOrDestField::Dest, 0b110101, 0b1010, 0).unwrap();
+        let header_len = primary_header.len_header();
+        buf[header_len] = ((ConstructionRule::NoSegmentation as u8) << 5)
+            | (UslpProtocolId::UserDefinedOctetStream as u8) & 0b11111;
+        buf[header_len + 1] = 0x42;
+        // 1 byte TFDH, 1 byte data, 2 bytes CRC.
+        primary_header.set_frame_len(header_len + 4);
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+        // Calculate and write CRC16.
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&buf[0..header_len + 2]);
+        buf[header_len + 2..header_len + 4].copy_from_slice(&digest.finalize().to_be_bytes());
+        // Now parse the frame.
+        let frame = TransferFrameReader::from_bytes(&buf, true).unwrap();
+        assert_eq!(*frame.primary_header(), primary_header);
+        assert_eq!(frame.data().len(), 1);
+        assert_eq!(frame.data()[0], 0x42);
+        assert_eq!(
+            frame.data_field_header().uslp_protocol_id(),
+            UslpProtocolId::UserDefinedOctetStream
+        );
+        assert_eq!(
+            frame.data_field_header().construction_rule(),
+            ConstructionRule::NoSegmentation
+        );
+        assert!(frame.data_field_header().fhp_or_lvo().is_none());
+        assert_eq!(frame.len_frame(), 11);
+        assert!(frame.operational_control_field().is_none());
+    }
+
+    #[test]
+    fn test_frame_parser_invalid_checksum() {
+        let mut buf: [u8; 32] = [0; 32];
+        // Build a variable frame manually.
+        let mut primary_header =
+            PrimaryHeader::new(0x01, SourceOrDestField::Dest, 0b110101, 0b1010, 0).unwrap();
+        let header_len = primary_header.len_header();
+        buf[header_len] = ((ConstructionRule::NoSegmentation as u8) << 5)
+            | (UslpProtocolId::UserDefinedOctetStream as u8) & 0b11111;
+        buf[header_len + 1] = 0x42;
+        // 1 byte TFDH, 1 byte data, 2 bytes CRC.
+        primary_header.set_frame_len(header_len + 4);
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+        // Now parse the frame without having calculated the checksum.
+        match TransferFrameReader::from_bytes(&buf, true) {
+            Ok(_) => panic!("transfer frame read call did not fail"),
+            Err(e) => {
+                assert_eq!(e, UslpError::ChecksumFailure(0));
+            }
+        }
+    }
+
+    #[test]
+    fn test_frame_parser_buf_too_small() {
+        let mut buf: [u8; 32] = [0; 32];
+        // Build a variable frame manually.
+        let mut primary_header =
+            PrimaryHeader::new(0x01, SourceOrDestField::Dest, 0b110101, 0b1010, 0).unwrap();
+        let header_len = primary_header.len_header();
+        buf[header_len] = ((ConstructionRule::NoSegmentation as u8) << 5)
+            | (UslpProtocolId::UserDefinedOctetStream as u8) & 0b11111;
+        buf[header_len + 1] = 0x42;
+        // 1 byte TFDH, 1 byte data, 2 bytes CRC.
+        primary_header.set_frame_len(header_len + 4);
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+        // Now parse the frame.
+        let error = TransferFrameReader::from_bytes(&buf[0..7], true).unwrap_err();
+        assert_eq!(
+            error,
+            ByteConversionError::FromSliceTooSmall {
+                expected: primary_header.len_frame(),
+                found: 7
+            }
+            .into()
+        );
+    }
+
+    #[test]
+    fn test_from_bytes_too_small_0() {
+        let buf: [u8; 3] = [0; 3];
+        assert_eq!(
+            PrimaryHeader::from_bytes(&buf).unwrap_err(),
+            ByteConversionError::FromSliceTooSmall {
+                found: 3,
+                expected: 4
+            }
+            .into()
+        );
+    }
+
+    #[test]
+    fn test_from_bytes_too_small_1() {
+        let buf: [u8; 6] = [0; 6];
+        assert_eq!(
+            PrimaryHeader::from_bytes(&buf).unwrap_err(),
+            ByteConversionError::FromSliceTooSmall {
+                found: 6,
+                expected: 7
+            }
+            .into()
+        );
+    }
+
+    #[test]
+    fn test_from_bytes_truncated_not_supported() {
+        let mut buf: [u8; 7] = [0; 7];
+        let primary_header =
+            PrimaryHeader::new(0x01, SourceOrDestField::Dest, 0b110101, 0b1010, 0).unwrap();
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+        // Set truncated header flag manually.
+        buf[3] |= 0b1;
+        assert_eq!(
+            PrimaryHeader::from_bytes(&buf).unwrap_err(),
+            UslpError::HeaderIsTruncated
+        );
+    }
+
+    #[test]
+    fn test_from_bytes_too_small_2() {
+        let mut buf: [u8; 16] = [0; 16];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.set_vc_frame_count(4, 0x12345678).unwrap();
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+
+        assert_eq!(
+            PrimaryHeader::from_bytes(&buf[0..8]).unwrap_err(),
+            UslpError::ByteConversion(ByteConversionError::FromSliceTooSmall {
+                found: 8,
+                expected: 11
+            })
+        );
+    }
+
+    #[test]
+    fn test_invalid_version_number() {
+        let mut buf: [u8; 7] = [0; 7];
+        let primary_header =
+            PrimaryHeader::new(0x01, SourceOrDestField::Dest, 0b110101, 0b1010, 0).unwrap();
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+        buf[0] &= 0b00001111;
+        assert_eq!(
+            PrimaryHeader::from_bytes(&buf).unwrap_err(),
+            UslpError::InvalidVersionNumber(0)
+        );
+    }
+
+    #[test]
+    fn test_primary_header_buf_too_small() {
+        let primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        if let Err(ByteConversionError::ToSliceTooSmall { found, expected }) =
+            primary_header.write_to_be_bytes(&mut [0; 4])
+        {
+            assert_eq!(found, 4);
+            assert_eq!(expected, 7);
+        } else {
+            panic!("writing primary header did not fail or failed with wrong error");
+        }
+    }
+
+    #[test]
+    fn test_applicability_contr_rules() {
+        assert!(ConstructionRule::PacketSpanningMultipleFrames.applicable_to_fixed_len_tfdz());
+        assert!(ConstructionRule::StartOfMapaSduOrVcaSdu.applicable_to_fixed_len_tfdz());
+        assert!(ConstructionRule::ContinuingPortionOfMapaSdu.applicable_to_fixed_len_tfdz());
+        assert!(!ConstructionRule::OctetStream.applicable_to_fixed_len_tfdz());
+        assert!(!ConstructionRule::StartingSegment.applicable_to_fixed_len_tfdz());
+        assert!(!ConstructionRule::ContinuingSegment.applicable_to_fixed_len_tfdz());
+        assert!(!ConstructionRule::LastSegment.applicable_to_fixed_len_tfdz());
+        assert!(!ConstructionRule::NoSegmentation.applicable_to_fixed_len_tfdz());
+    }
+
+    #[test]
+    fn test_header_len_correctness() {
+        let mut tfdh = TransferFrameDataFieldHeader {
+            construction_rule: ConstructionRule::PacketSpanningMultipleFrames,
+            uslp_protocol_id: UslpProtocolId::UserDefinedOctetStream,
+            fhp_or_lvo: Some(0),
+        };
+        assert_eq!(tfdh.len_header(), 3);
+        tfdh = TransferFrameDataFieldHeader {
+            construction_rule: ConstructionRule::StartOfMapaSduOrVcaSdu,
+            uslp_protocol_id: UslpProtocolId::UserDefinedOctetStream,
+            fhp_or_lvo: Some(0),
+        };
+        assert_eq!(tfdh.len_header(), 3);
+        tfdh = TransferFrameDataFieldHeader {
+            construction_rule: ConstructionRule::ContinuingPortionOfMapaSdu,
+            uslp_protocol_id: UslpProtocolId::UserDefinedOctetStream,
+            fhp_or_lvo: Some(0),
+        };
+        assert_eq!(tfdh.len_header(), 3);
+        tfdh = TransferFrameDataFieldHeader {
+            construction_rule: ConstructionRule::OctetStream,
+            uslp_protocol_id: UslpProtocolId::UserDefinedOctetStream,
+            fhp_or_lvo: None,
+        };
+        assert_eq!(tfdh.len_header(), 1);
+    }
+
+    #[test]
+    fn test_frame_data_field_header_from_bytes_too_small() {
+        let buf: [u8; 0] = [];
+        assert_eq!(
+            TransferFrameDataFieldHeader::from_bytes(&buf).unwrap_err(),
+            ByteConversionError::FromSliceTooSmall {
+                found: 0,
+                expected: 1
+            }
+            .into()
+        );
+    }
+}

src/util.rs

@@ -1,9 +1,7 @@
 use crate::ByteConversionError;
-use core::fmt::{Debug, Display, Formatter};
+use core::fmt::Debug;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-#[cfg(feature = "std")]
-use std::error::Error;
 
 pub trait ToBeBytes {
     type ByteArray: AsRef<[u8]>;
@@ -15,10 +13,12 @@ pub trait ToBeBytes {
 impl ToBeBytes for () {
     type ByteArray = [u8; 0];
 
+    #[inline]
     fn written_len(&self) -> usize {
         0
     }
 
+    #[inline]
     fn to_be_bytes(&self) -> Self::ByteArray {
         []
     }
@@ -27,9 +27,12 @@ impl ToBeBytes for () {
 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)
     }
@@ -38,9 +41,12 @@ impl ToBeBytes for u8 {
 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)
     }
@@ -49,9 +55,12 @@ impl ToBeBytes for u16 {
 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)
     }
@@ -60,9 +69,12 @@ impl ToBeBytes for u32 {
 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)
     }
@@ -77,7 +89,6 @@ pub trait UnsignedEnum {
     fn value(&self) -> u64;
 
     #[cfg(feature = "alloc")]
-    #[cfg_attr(doc_cfg, doc(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();
@@ -87,65 +98,45 @@ pub trait UnsignedEnum {
 
 pub trait UnsignedEnumExt: UnsignedEnum + Debug + Copy + Clone + PartialEq + Eq {}
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum UnsignedByteFieldError {
     /// Value is too large for specified width of byte field.
-    ValueTooLargeForWidth {
+    #[error("value {value} too large for width {width}")]
-        width: usize,
+    ValueTooLargeForWidth { width: usize, value: u64 },
-        value: u64,
-    },
     /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
     /// applicable, for example for conversions.
+    #[error("invalid width {found}, expected {expected:?}")]
     InvalidWidth {
         found: usize,
         expected: Option<usize>,
     },
-    ByteConversionError(ByteConversionError),
+    #[error("byte conversion error: {0}")]
+    ByteConversionError(#[from] ByteConversionError),
 }
 
-impl From<ByteConversionError> for UnsignedByteFieldError {
-    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 {
@@ -178,10 +169,12 @@ impl UnsignedByteField {
 }
 
 impl UnsignedEnum for UnsignedByteField {
+    #[inline]
     fn size(&self) -> usize {
         self.width
     }
 
+    #[inline]
     fn value(&self) -> u64 {
         self.value_const()
     }
@@ -221,6 +214,7 @@ impl UnsignedEnum for UnsignedByteField {
 
 #[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,
 }
@@ -236,6 +230,7 @@ impl<TYPE: Copy + Into<u64>> GenericUnsignedByteField<TYPE> {
 }
 
 impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericUnsignedByteField<TYPE> {
+    #[inline]
     fn size(&self) -> usize {
         self.value.written_len()
     }
@@ -251,6 +246,7 @@ impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericUnsignedByteFie
         Ok(self.value.written_len())
     }
 
+    #[inline]
     fn value(&self) -> u64 {
         self.value_typed().into()
     }
@@ -276,6 +272,7 @@ impl From<UnsignedByteFieldU8> for UnsignedByteField {
 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 {
@@ -288,6 +285,7 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU8 {
 }
 
 impl From<UnsignedByteFieldU16> for UnsignedByteField {
+    #[inline]
     fn from(value: UnsignedByteFieldU16) -> Self {
         Self::new(2, value.value as u64)
     }
@@ -296,6 +294,7 @@ impl From<UnsignedByteFieldU16> for UnsignedByteField {
 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 {
@@ -308,6 +307,7 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU16 {
 }
 
 impl From<UnsignedByteFieldU32> for UnsignedByteField {
+    #[inline]
     fn from(value: UnsignedByteFieldU32) -> Self {
         Self::new(4, value.value as u64)
     }
@@ -316,6 +316,7 @@ impl From<UnsignedByteFieldU32> for UnsignedByteField {
 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 {
@@ -328,6 +329,7 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU32 {
 }
 
 impl From<UnsignedByteFieldU64> for UnsignedByteField {
+    #[inline]
     fn from(value: UnsignedByteFieldU64) -> Self {
         Self::new(8, value.value)
     }
@@ -336,6 +338,7 @@ impl From<UnsignedByteFieldU64> for UnsignedByteField {
 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 {