Merge pull request 'release-checklist: missing bullet point' (#29) from release-checklist-note into main

Reviewed-on: #29

.github/workflows/ci.yml

@@ -20,6 +20,21 @@ jobs:
           command: check
           args: --release
 
+  msrv:
+    name: Check with MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: 1.61.0
+          override: true
+          profile: minimal
+      - uses: actions-rs/cargo@v1
+        with:
+          command: check
+          args: --release
+
   cross-check:
     name: Check Cross
     runs-on: ubuntu-latest
@@ -58,6 +73,21 @@ jobs:
           command: fmt
           args: --all -- --check
 
+  check-doc:
+    name: Check Documentation Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+          profile: minimal
+      - uses: actions-rs/cargo@v1
+        with:
+          command: doc
+          args: --all-features
+
   clippy:
     name: Clippy
     runs-on: ubuntu-latest

.gitignore

@@ -0,0 +1,7 @@
+# Rust
+/target
+/Cargo.lock
+
+# CLion
+/.idea/*
+!/.idea/runConfigurations

.idea/runConfigurations/Check.xml

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

.idea/runConfigurations/Test.xml

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

CHANGELOG.md

@@ -8,6 +8,279 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.7.0-beta.1] 2023-08-28
+
+- Bump `zerocopy` dependency to v0.7.0
+
+## Changed
+
+- The `Tlv` and `Lv` API return `&[u8]` instead of `Option<&[u8]>`.
+- `ByteConversionError` error variants `ToSliceTooSmall` and `FromSliceTooSmall` are struct
+  variants now. `SizeMissmatch` was removed appropriately.
+- `UnsignedByteFieldError` error variants `ValueTooLargeForWidth` and `InvalidWidth` are struct
+  variants now.
+- `TimestampError` error variant `InvalidTimeCode` is struct variant now.
+
+## Added
+
+- Added `raw_data` API for `Tlv` and `Lv` to retrieve the whole `Lv`/`Tlv` slice if the object
+  was created from a raw bytestream.
+- Added `MsgToUserTlv` helper class which wraps a regular `Tlv` and adds some useful functionality.
+- `UnsignedByteField` and `GenericUnsignedByteField` `new` methods are `const` now.
+- `PduError` variants which contained a tuple variant with multiple fields were converted to a
+  struct variant.
+
+# Added
+
+- Added `pdu_datafield_len` getter function for `PduHeader`
+
+## Removed
+
+- `SizeMissmatch` because it is not required for the `ByteConversionError` error enumeration
+  anymore.
+
+# [v0.7.0-beta.0] 2023-08-16
+
+- Moved MSRV from v1.60 to v1.61.
+
+## Changed
+
+- `PusPacket` trait: `user_data` now returns `&[u8]` instead of `Option<&[u8]>`. Empty user data
+  can simply be an empty slice.
+- Moved ECSS TC components from `tc` to `ecss.tc`.
+- Moved ECSS TM components from `tm` to `ecss.tm`.
+- Converted `PusTc` class to more specialized `PusTcCreator` and `PusTcReader`
+  classes. The old `PusTc` class is deprecated now.
+- Converted `PusTm` class to more specialized `PusTmCreator` and `PusTmReader`
+  classes. The old `PusTm` class is deprecated now.
+- Implement `Display` and `Error` for `StdTimestampError` properly.
+- Remove some redundant `Error` suffixes for enum error variants.
+- `CommonPduConfig`: `new_with_defaults` replaced by `new_with_byte_fields`.
+
+## Added
+
+- `source_data` and `app_data` API provided for PUS TM and PUS TC reader classes. These simply
+  call `user_data` but are also in line with the PUS packet standard names for those fields.
+- Added new marker trait `IsPusTelemetry` implemented by `PusTmCreator` and `PusTmReader`.
+- Added new marker trait `IsPusTelecommand` implemented by `PusTcCreator` and `PusTcReader`.
+- `metadata_param` getter method for the `MetadataPdu` object.
+- `Default` impl for CFDP `ChecksumType`
+- `Default` impl for CFDP `CommonPduConfig`
+
+## Fixed
+
+- All `MetadataGenericParam` fields are now public.
+- New setter method `set_source_and_dest_id` for `CommonPduConfig`.
+
+# [v0.6.0] 2023-07-06
+
+## Added
+
+- Added new `util` module which contains the following (new) helper modules:
+  - `UnsignedEnum` trait as an abstraction for unsigned byte fields with variable lengths. It is
+    not tied to the ECSS PFC value like the `EcssEnumeration` trait. The method to retrieve
+    the size of the unsigned enumeration in bytes is now called `size`.
+  - `GenericUnsignedByteField<TYPE>` and helper typedefs `UnsignedU8`, `UnsignedU16`, `UnsignedU32`
+    and `UnsignedU64` as helper types implementing `UnsignedEnum`
+  - `UnsignedByteField` as a type-erased helper.
+- Initial CFDP support: Added PDU packet implementation.
+- Added `SerializablePusPacket` as a generic abstraction for PUS packets which are
+  writable.
+- Added new `PusTmZeroCopyWriter` class which allows to set fields on a raw TM packet,
+  which might be more efficient that modification and re-writing a packet with the
+  `PusTm` object.
+
+## Changed
+ 
+- The `EcssEnumeration` now requires the `UnsignedEnum` trait and only adds the `pfc` method to it.
+- Renamed `byte_width` usages to `size` (part of new `UnsignedEnum` trait)
+- Moved `ecss::CRC_CCITT_FALSE` CRC constant to the root module. This CRC type is not just used by
+  the PUS standard, but by the CCSDS Telecommand standard and the CFDP standard as well.
+
+# [v0.5.4] 2023-02-12
+
+## Added
+
+- `Clone` trait requirement for `time::cds::ProvidesDaysLen` trait.
+- Added `Copy` and `Clone` derives for `DaysLen16Bits` and `DaysLen24Bits`.
+
+# [v0.5.3] 2023-02-05
+
+## Added
+
+- `num_enum` dependency to avoid boilerplate code for primtive to enum conversions, for example
+  for the PUS subservices.
+- `ecss.event` module containing a `Subservice` enum.
+- `ecss.verification` module containing a `Subservice` enum.
+- `ecss.scheduling` module containing a `Subservice` enum and some other helper enumerations.
+- `ecss.hk` module containing a `Subservice` enum.
+
+## Changed
+
+- Added missing Service IDs to `ecss.PusServiceId` and marked in `#[non_exhaustive]`.
+
+## Fixed
+
+- `time.UnixTimestamp`: All constructors and `From` conversions now use the `new` constructor,
+  which should cause a correct conversion of 0 subsecond milliseconds to a `None` value.
+
+# [v0.5.2] 2023-01-26
+
+## Added
+
+- Added `.gitignore`.
+
+## Fixed
+
+- Correct implementation of Trait `PartialEq` for `PusTc` and `PusTm`. The previous auto-derivation
+  were incorrect because they also compared fields unrelated to the raw byte representation.
+
+## Changed
+
+- Renamed `PusTc` `raw` method to `raw_bytes` and add better docs to avoid confusion.
+  Deprecate `raw` to avoid breaking change.
+- Added `raw_bytes` method to `PusTm`.
+
+# [v0.5.1] 2023-01-22
+
+## Added
+
+- `time::cds::TimeProvider`
+  - Add `Ord` and `PartialOrd`, use custom `PartialEq` impl to account for precision correctly.
+  - Add `precision_as_ns` function which converts microsecond and picosecond precision values
+    into nanoseconds.
+  - Add conversion trait to convert `cds::TimeProvider<DaysLen16Bits>` into
+    `cds::TimeProvider<DaysLen24Bits>` and vice-versa.
+- `time::UnixTimestamp`
+  - Add `Ord` and `PartialOrd` implementations.
+  - Add `Add<Duration>` and `AddAssign<Duration>` implementations.
+
+## Fixed
+
+- `time::cds::TimeProvider`: Fixed a bug where subsecond milliseconds were not accounted for
+  when the provider has no submillisecond precision.
+
+# [v0.5.0] 2023-01-20
+
+The timestamp of `PusTm` is now optional. See Added and Changed section for details.
+
+## Added
+
+- `PusTmSecondaryHeader`: New `new_simple_no_timestamp` API to create secondary header without
+  timestamp.
+- `PusTm`: Add `new_simple_no_timestamp` method to create TM without timestamp
+- New `UnixTimestamp` abstraction which contains the unix seconds as an `i64`
+  and an optional subsecond millisecond counter (`u16`)
+- `MS_PER_DAY` constant.
+- CUC: Added `from_date_time` and `from_unix_stamp` constructors for time provider.
+- CUC: Add `Add<Duration>` and `AddAssign<Duration>` impl for time provider.
+
+### CDS time module
+
+- Implement `Add<Duration>` and `AddAssign<Duration>` for time providers, which allows
+  easily adding offsets to the providers.
+- Implement `TryFrom<DateTime<Utc>>` for time providers.
+- `get_dyn_time_provider_from_bytes`: Requires `alloc` support and returns
+  the correct `TimeProvider` instance wrapped as a boxed trait object
+  `Box<DynCdsTimeProvider>` by checking the length of days field.
+- Added constructor function to create the time provider
+  from `chrono::DateTime<Utc>` and a generic UNIX timestamp (`i64` seconds
+  and subsecond milliseconds).
+- `MAX_DAYS_24_BITS` which contains maximum value which can be supplied
+  to the days field of a CDS time provider with 24 bits days field width.
+- New `CdsTimestamp` trait which encapsulates common fields for all CDS time providers.
+- `from_unix_secs_with_u24_days` and `from_unix_secs_with_u16_days` which create
+   the time provider from a `UnixTimestamp` reference.
+- `from_dt_with_u16_days`, `from_dt_with_u24_days` and their `..._us_precision` and
+   `..._ps_precision` variants which allow to create time providers from
+   a `chrono::DateTime<Utc>`.
+- Add `from_bytes_with_u24_days` and `from_bytes_with_u16_days` associated methods
+
+## Changed
+
+
+- (breaking) `unix_epoch_to_ccsds_epoch`: Expect and return `i64` instead of `u64` now.
+- (breaking) `ccsds_epoch_to_unix_epoch`: Expect and return `i64` instead of `u64` now.
+- (breaking) `PusTmSecondaryHeader`: Timestamp is optional now, which translates to a
+  timestamp of size 0.
+- (breaking): `PusTm`: Renamed `time_stamp` method to `timestamp`, also returns
+  `Optional<&'src_data [u8]>` now.
+- (breaking): `PusTmSecondaryHeader`: Renamed `time_stamp` field to `timestamp` for consistency.
+- (breaking): Renamed `from_now_with_u24_days_and_us_prec` to `from_now_with_u24_days_us_precision`.
+  Also did the same for the `u16` variant.
+- (breaking): Renamed `from_now_with_u24_days_and_ps_prec` to `from_now_with_u24_days_ps_precision`.
+  Also did the same for the `u16` variant.
+- `CcsdsTimeProvider` trait (breaking):
+  - Add new `unix_stamp` method returning the new `UnixTimeStamp` struct.
+  - Add new  `subsecond_millis` method returning counter `Option<u16>`.
+  - Default impl for `unix_stamp` which re-uses `subsecond_millis` and
+    existing `unix_seconds` method.
+- `TimestampError` (breaking): Add `DateBeforeCcsdsEpoch` error type
+  because new CDS API allow supplying invalid date times before CCSDS epoch.
+  Make `TimestampError` with `#[non_exhaustive]` attribute to prevent
+  future breakages if new error variants are added.
+
+# [v0.4.2] 14.01.2023
+
+## Fixed
+
+- CDS timestamp: Fixed another small logic error for stamp creation from the current
+  time with picosecond precision.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/8
+
+# [v0.4.1] 14.01.2023
+
+## Fixed
+
+- CDS timestamp: The conversion function from the current time were buggy
+  when specifying picoseconds precision, which could lead to overflow
+  multiplications and/or incorrect precision fields.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/7
+
+# [v0.4.0] 10.01.2023
+
+## Fixed
+
+- Remove `Default` derive on CDS time provider. This can lead to uninitialized preamble fields.
+
+## Changed
+
+- `serde` support is now optional and behind the `serde` feature.
+- `PusTcSecondaryHeaderT` trait renamed to `GenericPusTcSecondaryHeader`.
+- `PusTmSecondaryHeaderT` trait renamed to `GenericPusTmSecondaryHeader`.
+- `SpHeader`: Former `tc` and `tm` methods now named `tc_unseg` and `tm_unseg`.
+  Former `new` method now called `new_from_single_fields`.
+- `SpHeader`: Renamed `from_bytes` to `from_be_bytes`.
+  The function now returns the remaining slice as well.
+- All CDS specific functionality was moved into the `cds` submodule of the `time`
+  module. `CdsShortTimeProvider` was renamed to `TimeProvider`.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/3
+
+## Added
+
+- `SpHeader` getter function `sp_header` added for `PusTc`
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/6
+- Added PFC enumerations: `ecss::UnsignedPfc` and `ecss::RealPfc`.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/5
+- Added `std::error::Error` implementation for all error enumerations if the `std` feature
+  is enabled.
+- CUC timestamp implementation as specified in CCSDS 301.0-B-4 section 3.2.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/4/files
+- ACII timestamps as specified in CCSDS 301.0-B-4 section 3.5.
+- Added MSRV in `Cargo.toml` with the `rust-version` field set to Rust 1.60.
+- `serde` `Serialize` and `Deserialize` added to all types.
+- Added `const` constructors for `PacketId`, `PacketSeqCtrl` and
+  `SpHeader`.
+- Added `PartialEq` and `Eq` `derive`s to `TimeProvider`.
+- `SpHeader`: Added serialization function into raw format `write_to_be_bytes`.
+- Added 24-bit day field support for CDS short. The bit width is configured at type level
+  via a generic parameter type passed to the `cds::TimeProvider`
+- Added submillisecond precision support for `cds::TimeProvider`
+
+# [v0.3.1] 03.12.2022
+
+- Small fix for faulty docs.rs build
+
 # [v0.3.0] 01.12.2022
 
 ## Added

Cargo.toml

@@ -1,7 +1,8 @@
 [package]
 name = "spacepackets"
-version = "0.3.0"
+version = "0.7.0-beta.1"
 edition = "2021"
+rust-version = "1.61"
 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"
@@ -12,12 +13,24 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-zerocopy = "0.6"
-crc = "3.0"
-delegate = "0.8"
+crc = "3"
+delegate = ">=0.8, <0.11"
+
+[dependencies.zerocopy]
+version = "0.7"
+features = ["derive"]
+
+[dependencies.thiserror]
+version = "1"
+optional = true
+
+[dependencies.num_enum]
+version = ">0.5, <=0.7"
+default-features = false
 
 [dependencies.serde]
-version = "1.0"
+version = "1"
+optional = true
 default-features = false
 features = ["derive"]
 
@@ -30,12 +43,13 @@ version = "0.2"
 default-features = false
 
 [dev-dependencies.postcard]
-version = "1.0"
+version = "1"
 
 [features]
 default = ["std"]
-std = ["chrono/std", "chrono/clock", "alloc"]
-alloc = ["postcard/alloc"]
+std = ["chrono/std", "chrono/clock", "alloc", "thiserror"]
+serde = ["dep:serde", "chrono/serde"]
+alloc = ["postcard/alloc", "chrono/alloc"]
 
 [package.metadata.docs.rs]
 all-features = true

NOTICE

@@ -1,3 +1,3 @@
 Generic implementations for various CCSDS and ECSS packet standards.
 
-This software contains code developed at the University of Stuttgart.
+This software contains code developed at the University of Stuttgart's Institute of Space Systems.

README.md

@@ -13,27 +13,36 @@ Currently, this includes the following components:
 
 - Space Packet implementation according to
   [CCSDS Blue Book 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf)
+- CCSDS File Delivery Protocol (CFDP) packet implementations according to
+  [CCSDS Blue Book 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf)
 - PUS Telecommand and PUS Telemetry implementation according to the
   [ECSS-E-ST-70-41C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
-- CDS Short Time Code implementation according to
-  [CCSDS CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
- 
+- CUC (CCSDS Unsegmented Time Code) implementation according to
+  [CCSDS 301.0-B-4 3.2](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
+- CDS (CCSDS Day Segmented Time Code) implementation according to
+  [CCSDS 301.0-B-4 3.3](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
+- Some helper types to support ASCII timecodes as specified in
+  [CCSDS 301.0-B-4 3.5](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
+
 # Features
 
 `spacepackets` supports various runtime environments and is also suitable for `no_std` environments.
 
-It offers support for [`serde`](https://serde.rs/). The Space Packet, PUS TM and TC
-implementations derive the `serde` `Serialize` and `Deserialize` trait. This allows serializing and
+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:
+## Default features
 
  - [`std`](https://doc.rust-lang.org/std/): Enables functionality relying on the standard library.
  - [`alloc`](https://doc.rust-lang.org/alloc/): Enables features which operate on containers
    like [`alloc::vec::Vec`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html).
    Enabled by the `std` feature.
 
+## Optional Features
+
+ - [`serde`](https://serde.rs/): Adds `serde` support for most types by adding `Serialize` and `Deserialize` `derive`s
+
 # Examples
 
 You can check the [documentation](https://docs.rs/spacepackets) of individual modules for various

automation/Dockerfile

@@ -10,6 +10,6 @@ ARG DEBIAN_FRONTEND=noninteractive
 # set CROSS_CONTAINER_IN_CONTAINER to inform `cross` that it is executed from within a container
 ENV CROSS_CONTAINER_IN_CONTAINER=true
 
-# TODO: installing cross is problematic, permission issues
-RUN rustup target add thumbv7em-none-eabihf armv7-unknown-linux-gnueabihf && \
+RUN rustup install nightly && \
+    rustup target add thumbv7em-none-eabihf armv7-unknown-linux-gnueabihf && \
     rustup component add rustfmt clippy

automation/Jenkinsfile

@@ -13,19 +13,29 @@ pipeline {
                 sh 'cargo clippy'
             }
         }
+        stage('Docs') {
+            steps {
+                sh 'cargo +nightly doc --all-features'
+            }
+        }
         stage('Rustfmt') {
             steps {
-                sh 'cargo fmt'
+                sh 'cargo fmt --all --check'
             }
         }
         stage('Test') {
             steps {
-                sh 'cargo test'
+                sh 'cargo test --all-features'
             }
         }
-        stage('Check') {
+        stage('Check with all features') {
             steps {
-                sh 'cargo check'
+                sh 'cargo check --all-features'
+            }
+        }
+        stage('Check with no features') {
+            steps {
+                sh 'cargo check --no-default-features'
             }
         }
         stage('Check Cross Embedded Bare Metal') {

release-checklist.md

@@ -0,0 +1,22 @@
+Checklist for new releases
+=======
+
+# Pre-Release
+
+1. Make sure any new modules are documented sufficiently enough and check docs with
+   `cargo doc --all-features --open`.
+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`.
+5. Run `cargo fmt` and `cargo clippy`. Check `cargo msrv` against MSRV in `Cargo.toml`.
+6. Wait for CI/CD results for EGit and Github. These also check cross-compilation for bare-metal
+   targets.
+
+# Release
+
+1. `cargo publish`
+
+# Post-Release
+
+1. Create a new release on `EGit` based on the release branch.

src/cfdp/lv.rs

@@ -0,0 +1,329 @@
+//! Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
+use crate::cfdp::TlvLvError;
+use crate::ByteConversionError;
+use core::str::Utf8Error;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::string::String;
+
+pub const MIN_LV_LEN: usize = 1;
+
+/// Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
+///
+/// Please note that this class is zero-copy and does not generate a copy of the value data for
+/// both the regular [Self::new] constructor and the [Self::from_bytes] constructor.
+///
+/// # Lifetimes
+///  * `data`: If the LV is generated from a raw bytestream, this will be the lifetime of
+///    the raw bytestream. If the LV is generated from a raw slice or a similar data reference,
+///    this will be the lifetime of that data reference.
+#[derive(Debug, Copy, Clone, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct Lv<'data> {
+    data: &'data [u8],
+    // If the LV was generated from a raw bytestream, this will contain the start of the
+    // full LV.
+    pub(crate) raw_data: Option<&'data [u8]>,
+}
+
+impl PartialEq for Lv<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.data == other.data
+    }
+}
+
+pub(crate) fn generic_len_check_data_serialization(
+    buf: &[u8],
+    data_len: usize,
+    min_overhead: usize,
+) -> Result<(), ByteConversionError> {
+    if buf.len() < data_len + min_overhead {
+        return Err(ByteConversionError::ToSliceTooSmall {
+            found: buf.len(),
+            expected: data_len + min_overhead,
+        });
+    }
+    Ok(())
+}
+
+pub(crate) fn generic_len_check_deserialization(
+    buf: &[u8],
+    min_overhead: usize,
+) -> Result<(), ByteConversionError> {
+    if buf.len() < min_overhead {
+        return Err(ByteConversionError::FromSliceTooSmall {
+            found: buf.len(),
+            expected: min_overhead,
+        });
+    }
+    Ok(())
+}
+
+impl<'data> Lv<'data> {
+    pub fn new(data: &[u8]) -> Result<Lv, TlvLvError> {
+        if data.len() > u8::MAX as usize {
+            return Err(TlvLvError::DataTooLarge(data.len()));
+        }
+        Ok(Lv {
+            data,
+            raw_data: None,
+        })
+    }
+
+    /// Creates a LV with an empty value field.
+    pub fn new_empty() -> Lv<'data> {
+        Lv {
+            data: &[],
+            raw_data: None,
+        }
+    }
+
+    /// Helper function to build a string LV. This is especially useful for the file or directory
+    /// path LVs
+    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvError> {
+        Self::new(str_slice.as_bytes())
+    }
+
+    /// Helper function to build a string LV. This is especially useful for the file or directory
+    /// path LVs
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvError> {
+        Self::new(string.as_bytes())
+    }
+
+    /// Returns the length of the value part, not including the length byte.
+    pub fn len_value(&self) -> usize {
+        self.data.len()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    pub fn len_full(&self) -> usize {
+        self.len_value() + 1
+    }
+
+    /// Checks whether the value field is empty.
+    pub fn is_empty(&self) -> bool {
+        self.data.len() == 0
+    }
+
+    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.
+    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.
+    pub fn value_as_str(&self) -> Option<Result<&'data str, Utf8Error>> {
+        if self.is_empty() {
+            return None;
+        }
+        Some(core::str::from_utf8(self.data))
+    }
+
+    /// Writes the LV to a raw buffer. Please note that the first byte will contain the length
+    /// of the value, but the values may not exceed a length of [u8::MAX].
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        generic_len_check_data_serialization(buf, self.len_value(), MIN_LV_LEN)?;
+        Ok(self.write_to_be_bytes_no_len_check(buf))
+    }
+
+    /// Reads a LV  from a raw buffer.
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Lv<'data>, ByteConversionError> {
+        generic_len_check_deserialization(buf, MIN_LV_LEN)?;
+        Self::from_be_bytes_no_len_check(buf)
+    }
+
+    pub(crate) fn write_to_be_bytes_no_len_check(&self, buf: &mut [u8]) -> usize {
+        if self.is_empty() {
+            buf[0] = 0;
+            return MIN_LV_LEN;
+        }
+        // Length check in constructor ensures the length always has a valid value.
+        buf[0] = self.data.len() as u8;
+        buf[MIN_LV_LEN..self.data.len() + MIN_LV_LEN].copy_from_slice(self.data);
+        MIN_LV_LEN + self.data.len()
+    }
+
+    pub(crate) fn from_be_bytes_no_len_check(
+        buf: &'data [u8],
+    ) -> Result<Lv<'data>, ByteConversionError> {
+        let value_len = buf[0] as usize;
+        generic_len_check_deserialization(buf, value_len + MIN_LV_LEN)?;
+        Ok(Self {
+            data: &buf[MIN_LV_LEN..MIN_LV_LEN + value_len],
+            raw_data: Some(buf),
+        })
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::TlvLvError;
+    use crate::ByteConversionError;
+    use std::string::String;
+
+    #[test]
+    fn test_basic() {
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv_res = Lv::new(&lv_data);
+        assert!(lv_res.is_ok());
+        let lv = lv_res.unwrap();
+        assert!(lv.value().len() > 0);
+        let val = lv.value();
+        assert_eq!(val[0], 1);
+        assert_eq!(val[1], 2);
+        assert_eq!(val[2], 3);
+        assert_eq!(val[3], 4);
+        assert!(!lv.is_empty());
+        assert_eq!(lv.len_full(), 5);
+        assert_eq!(lv.len_value(), 4);
+    }
+
+    #[test]
+    fn test_empty() {
+        let lv_empty = Lv::new_empty();
+        assert_eq!(lv_empty.len_value(), 0);
+        assert_eq!(lv_empty.len_full(), 1);
+        assert!(lv_empty.is_empty());
+        let mut buf: [u8; 4] = [0xff; 4];
+        let res = lv_empty.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 1);
+        assert_eq!(buf[0], 0);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv_res = Lv::new(&lv_data);
+        assert!(lv_res.is_ok());
+        let lv = lv_res.unwrap();
+        let mut buf: [u8; 16] = [0; 16];
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 5);
+        assert_eq!(buf[0], 4);
+        assert_eq!(buf[1], 1);
+        assert_eq!(buf[2], 2);
+        assert_eq!(buf[3], 3);
+        assert_eq!(buf[4], 4);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let mut buf: [u8; 16] = [0; 16];
+        buf[0] = 4;
+        buf[1] = 1;
+        buf[2] = 2;
+        buf[3] = 3;
+        buf[4] = 4;
+        let lv = Lv::from_bytes(&buf);
+        assert!(lv.is_ok());
+        let lv = lv.unwrap();
+        assert!(!lv.is_empty());
+        assert_eq!(lv.len_value(), 4);
+        assert_eq!(lv.len_full(), 5);
+        assert!(lv.raw_data().is_some());
+        assert_eq!(lv.raw_data().unwrap(), buf);
+        let val = lv.value();
+        assert_eq!(val[0], 1);
+        assert_eq!(val[1], 2);
+        assert_eq!(val[2], 3);
+        assert_eq!(val[3], 4);
+    }
+
+    #[test]
+    fn test_deserialization_empty() {
+        let buf: [u8; 2] = [0; 2];
+        let lv_empty = Lv::from_bytes(&buf);
+        assert!(lv_empty.is_ok());
+        let lv_empty = lv_empty.unwrap();
+        assert!(lv_empty.is_empty());
+    }
+
+    #[test]
+    fn test_data_too_large() {
+        let data_big: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
+        let lv = Lv::new(&data_big);
+        assert!(lv.is_err());
+        let error = lv.unwrap_err();
+        if let TlvLvError::DataTooLarge(size) = error {
+            assert_eq!(size, u8::MAX as usize + 1);
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+
+    #[test]
+    fn test_serialization_buf_too_small() {
+        let mut buf: [u8; 3] = [0; 3];
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv = Lv::new(&lv_data).unwrap();
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let ByteConversionError::ToSliceTooSmall { found, expected } = error {
+            assert_eq!(expected, 5);
+            assert_eq!(found, 3);
+        } else {
+            panic!("invalid error {}", error);
+        }
+    }
+
+    #[test]
+    fn test_deserialization_buf_too_small() {
+        let mut buf: [u8; 3] = [0; 3];
+        buf[0] = 4;
+        let res = Lv::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let ByteConversionError::FromSliceTooSmall { found, expected } = error {
+            assert_eq!(found, 3);
+            assert_eq!(expected, 5);
+        } else {
+            panic!("invalid error {}", error);
+        }
+    }
+
+    fn verify_test_str_lv(lv: Lv) {
+        let mut buf: [u8; 16] = [0; 16];
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let res = res.unwrap();
+        assert_eq!(res, 8 + 1);
+        assert_eq!(buf[0], 8);
+        assert_eq!(buf[1], b't');
+        assert_eq!(buf[2], b'e');
+        assert_eq!(buf[3], b's');
+        assert_eq!(buf[4], b't');
+        assert_eq!(buf[5], b'.');
+        assert_eq!(buf[6], b'b');
+        assert_eq!(buf[7], b'i');
+        assert_eq!(buf[8], b'n');
+    }
+    #[test]
+    fn test_str_helper() {
+        let test_str = "test.bin";
+        let str_lv = Lv::new_from_str(test_str);
+        assert!(str_lv.is_ok());
+        verify_test_str_lv(str_lv.unwrap());
+    }
+
+    #[test]
+    fn test_string_helper() {
+        let string = String::from("test.bin");
+        let str_lv = Lv::new_from_string(&string);
+        assert!(str_lv.is_ok());
+        verify_test_str_lv(str_lv.unwrap());
+    }
+}

src/cfdp/mod.rs

@@ -0,0 +1,209 @@
+//! Low-level CCSDS File Delivery Protocol (CFDP) support according to [CCSDS 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf).
+use crate::ByteConversionError;
+use core::fmt::{Display, Formatter};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub mod lv;
+pub mod pdu;
+pub mod tlv;
+
+/// This is the name of the standard this module is based on.
+pub const CFDP_VERSION_2_NAME: &str = "CCSDS 727.0-B-5";
+/// Currently, only this version is supported.
+pub const CFDP_VERSION_2: u8 = 0b001;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum PduType {
+    FileDirective = 0,
+    FileData = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum Direction {
+    TowardsReceiver = 0,
+    TowardsSender = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum TransmissionMode {
+    Acknowledged = 0,
+    Unacknowledged = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum CrcFlag {
+    NoCrc = 0,
+    WithCrc = 1,
+}
+
+/// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum SegmentMetadataFlag {
+    NotPresent = 0,
+    Present = 1,
+}
+
+/// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum SegmentationControl {
+    NoRecordBoundaryPreservation = 0,
+    WithRecordBoundaryPreservation = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FaultHandlerCode {
+    NoticeOfCancellation = 0b0001,
+    NoticeOfSuspension = 0b0010,
+    IgnoreError = 0b0011,
+    AbandonTransaction = 0b0100,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum LenInBytes {
+    ZeroOrNone = 0,
+    OneByte = 1,
+    TwoBytes = 2,
+    ThreeBytes = 4,
+    FourBytes = 8,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum ConditionCode {
+    /// This is not an error condition for which a faulty handler override can be specified
+    NoError = 0b0000,
+    PositiveAckLimitReached = 0b0001,
+    KeepAliveLimitReached = 0b0010,
+    InvalidTransmissionMode = 0b0011,
+    FilestoreRejection = 0b0100,
+    FileChecksumFailure = 0b0101,
+    FileSizeError = 0b0110,
+    NakLimitReached = 0b0111,
+    InactivityDetected = 0b1000,
+    CheckLimitReached = 0b1001,
+    UnsupportedChecksumType = 0b1011,
+    /// Not an actual fault condition for which fault handler overrides can be specified
+    SuspendRequestReceived = 0b1110,
+    /// Not an actual fault condition for which fault handler overrides can be specified
+    CancelRequestReceived = 0b1111,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum LargeFileFlag {
+    /// 32 bit maximum file size and FSS size
+    Normal = 0,
+    /// 64 bit maximum file size and FSS size
+    Large = 1,
+}
+
+/// Checksum types according to the
+/// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum ChecksumType {
+    /// Modular legacy checksum
+    Modular = 0,
+    Crc32Proximity1 = 1,
+    Crc32C = 2,
+    /// Polynomial: 0x4C11DB7. Preferred checksum for now.
+    Crc32 = 3,
+    NullChecksum = 15,
+}
+
+impl Default for ChecksumType {
+    fn default() -> Self {
+        Self::NullChecksum
+    }
+}
+
+pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum TlvLvError {
+    DataTooLarge(usize),
+    ByteConversionError(ByteConversionError),
+    /// First value: Found value. Second value: Expected value if there is one.
+    InvalidTlvTypeField((u8, Option<u8>)),
+    /// Logically invalid value length detected. The value length may not exceed 255 bytes.
+    /// Depending on the concrete TLV type, the value length may also be logically invalid.
+    InvalidValueLength(usize),
+    /// Only applies to filestore requests and responses. Second name was missing where one is
+    /// expected.
+    SecondNameMissing,
+    /// Invalid action code for filestore requests or responses.
+    InvalidFilestoreActionCode(u8),
+}
+
+impl From<ByteConversionError> for TlvLvError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(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::ByteConversionError(e) => {
+                write!(f, "{}", e)
+            }
+            TlvLvError::InvalidTlvTypeField((found, expected)) => {
+                write!(
+                    f,
+                    "invalid TLV type field, found {found}, possibly expected {expected:?}"
+                )
+            }
+            TlvLvError::InvalidValueLength(len) => {
+                write!(f, "invalid value length {len} detected")
+            }
+            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::ByteConversionError(e) => Some(e),
+            _ => None,
+        }
+    }
+}

src/cfdp/pdu/eof.rs

@@ -0,0 +1,209 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::EntityIdTlv;
+use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
+use crate::ByteConversionError;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+/// Finished PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.2.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct EofPdu {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    file_checksum: u32,
+    file_size: u64,
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl EofPdu {
+    pub fn new_no_error(pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+        let mut eof_pdu = Self {
+            pdu_header,
+            condition_code: ConditionCode::NoError,
+            file_checksum,
+            file_size,
+            fault_location: None,
+        };
+        eof_pdu.pdu_header.pdu_datafield_len = eof_pdu.calc_pdu_datafield_len() as u16;
+        eof_pdu
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn file_checksum(&self) -> u32 {
+        self.file_checksum
+    }
+
+    pub fn file_size(&self) -> u64 {
+        self.file_size
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        // One directive type octet, 4 bits condition code, 4 spare bits.
+        let mut len = 2 + core::mem::size_of::<u32>() + 4;
+        if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
+            len += 4;
+        }
+        if let Some(fault_location) = self.fault_location {
+            len += fault_location.len_full();
+        }
+        len
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.written_len();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = (self.condition_code as u8) << 4;
+        current_idx += 1;
+        buf[current_idx..current_idx + 4].copy_from_slice(&self.file_checksum.to_be_bytes());
+        current_idx += 4;
+        current_idx += write_fss_field(
+            self.pdu_header.pdu_conf.file_flag,
+            self.file_size,
+            &mut buf[current_idx..],
+        )?;
+        if let Some(fault_location) = self.fault_location {
+            current_idx += fault_location.write_to_be_bytes(buf)?;
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<EofPdu, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let is_large_file = pdu_header.pdu_conf.file_flag == LargeFileFlag::Large;
+        let mut min_expected_len = 2 + 4 + 4;
+        if is_large_file {
+            min_expected_len += 4;
+        }
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::EofPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::EofPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::EofPdu,
+            });
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        current_idx += 1;
+        let file_checksum =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        current_idx += 4;
+        let (fss_field_len, file_size) =
+            read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
+        current_idx += fss_field_len;
+        let mut fault_location = None;
+        if condition_code != ConditionCode::NoError && current_idx < full_len_without_crc {
+            fault_location = Some(EntityIdTlv::from_bytes(&buf[current_idx..])?);
+        }
+        Ok(Self {
+            pdu_header,
+            condition_code,
+            file_checksum,
+            file_size,
+            fault_location,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::eof::EofPdu;
+    use crate::cfdp::pdu::tests::{common_pdu_conf, verify_raw_header};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
+
+    #[test]
+    fn test_basic() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        assert_eq!(eof_pdu.written_len(), pdu_header.header_len() + 2 + 4 + 4);
+        assert_eq!(eof_pdu.file_checksum(), 0x01020304);
+        assert_eq!(eof_pdu.file_size(), 12);
+        assert_eq!(eof_pdu.condition_code(), ConditionCode::NoError);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = eof_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, eof_pdu.written_len());
+        verify_raw_header(eof_pdu.pdu_header(), &buf);
+        let mut current_idx = eof_pdu.pdu_header().header_len();
+        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        current_idx += 1;
+        assert_eq!(
+            (buf[current_idx] >> 4) & 0b1111,
+            ConditionCode::NoError as u8
+        );
+        current_idx += 1;
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            0x01020304
+        );
+        current_idx += 4;
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            12
+        );
+        current_idx += 4;
+        assert_eq!(current_idx, written);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        eof_pdu.write_to_bytes(&mut buf).unwrap();
+        let eof_read_back = EofPdu::from_bytes(&buf);
+        if !eof_read_back.is_ok() {
+            let e = eof_read_back.unwrap_err();
+            panic!("deserialization failed with: {e}")
+        }
+        let eof_read_back = eof_read_back.unwrap();
+        assert_eq!(eof_read_back, eof_pdu);
+    }
+}

src/cfdp/pdu/file_data.rs

@@ -0,0 +1,397 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    PduError, PduHeader,
+};
+use crate::cfdp::{CrcFlag, LargeFileFlag, PduType, SegmentMetadataFlag};
+use crate::ByteConversionError;
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum RecordContinuationState {
+    NoStartNoEnd = 0b00,
+    StartWithoutEnd = 0b01,
+    EndWithoutStart = 0b10,
+    StartAndEnd = 0b11,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct SegmentMetadata<'seg_meta> {
+    record_continuation_state: RecordContinuationState,
+    metadata: Option<&'seg_meta [u8]>,
+}
+
+impl<'seg_meta> SegmentMetadata<'seg_meta> {
+    pub fn new(
+        record_continuation_state: RecordContinuationState,
+        metadata: Option<&'seg_meta [u8]>,
+    ) -> Option<Self> {
+        if let Some(metadata) = metadata {
+            if metadata.len() > 2_usize.pow(6) - 1 {
+                return None;
+            }
+        }
+        Some(Self {
+            record_continuation_state,
+            metadata,
+        })
+    }
+
+    pub fn written_len(&self) -> usize {
+        // Map empty metadata to 0 and slice to its length.
+        1 + self.metadata.map_or(0, |meta| meta.len())
+    }
+
+    pub(crate) fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.written_len() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.written_len(),
+            });
+        }
+        buf[0] = ((self.record_continuation_state as u8) << 6)
+            | self.metadata.map_or(0, |meta| meta.len() as u8);
+        if let Some(metadata) = self.metadata {
+            buf[1..1 + metadata.len()].copy_from_slice(metadata)
+        }
+        Ok(self.written_len())
+    }
+
+    pub(crate) fn from_bytes(buf: &'seg_meta [u8]) -> Result<Self, ByteConversionError> {
+        if buf.is_empty() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 2,
+            });
+        }
+        let mut metadata = None;
+        let seg_metadata_len = (buf[0] & 0b111111) as usize;
+        if seg_metadata_len > 0 {
+            metadata = Some(&buf[1..1 + seg_metadata_len]);
+        }
+        Ok(Self {
+            // Can't fail, only 2 bits
+            record_continuation_state: RecordContinuationState::try_from((buf[0] >> 6) & 0b11)
+                .unwrap(),
+            metadata,
+        })
+    }
+}
+
+/// File Data PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FileDataPdu<'seg_meta, 'file_data> {
+    pdu_header: PduHeader,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+    offset: u64,
+    file_data: &'file_data [u8],
+}
+
+impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
+    pub fn new_with_seg_metadata(
+        pdu_header: PduHeader,
+        segment_metadata: SegmentMetadata<'seg_meta>,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        Self::new_generic(pdu_header, Some(segment_metadata), offset, file_data)
+    }
+
+    pub fn new_no_seg_metadata(
+        pdu_header: PduHeader,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        Self::new_generic(pdu_header, None, offset, file_data)
+    }
+
+    pub fn new_generic(
+        mut pdu_header: PduHeader,
+        segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileData;
+        if segment_metadata.is_some() {
+            pdu_header.seg_metadata_flag = SegmentMetadataFlag::Present;
+        }
+        let mut pdu = Self {
+            pdu_header,
+            segment_metadata,
+            offset,
+            file_data,
+        };
+        pdu.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        let mut len = core::mem::size_of::<u32>();
+        if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
+            len += 4;
+        }
+        if self.segment_metadata.is_some() {
+            len += self.segment_metadata.as_ref().unwrap().written_len()
+        }
+        len += self.file_data.len();
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    pub fn offset(&self) -> u64 {
+        self.offset
+    }
+
+    pub fn file_data(&self) -> &'file_data [u8] {
+        self.file_data
+    }
+
+    pub fn segment_metadata(&self) -> Option<&SegmentMetadata> {
+        self.segment_metadata.as_ref()
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        if buf.len() < self.written_len() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.written_len(),
+            }
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        if self.segment_metadata.is_some() {
+            current_idx += self
+                .segment_metadata
+                .as_ref()
+                .unwrap()
+                .write_to_bytes(&mut buf[current_idx..])?;
+        }
+        current_idx += write_fss_field(
+            self.pdu_header.common_pdu_conf().file_flag,
+            self.offset,
+            &mut buf[current_idx..],
+        )?;
+        buf[current_idx..current_idx + self.file_data.len()].copy_from_slice(self.file_data);
+        current_idx += self.file_data.len();
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes<'longest: 'seg_meta + 'file_data>(
+        buf: &'longest [u8],
+    ) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let min_expected_len = current_idx + core::mem::size_of::<u32>();
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let mut segment_metadata = None;
+        if pdu_header.seg_metadata_flag == SegmentMetadataFlag::Present {
+            segment_metadata = Some(SegmentMetadata::from_bytes(&buf[current_idx..])?);
+            current_idx += segment_metadata.as_ref().unwrap().written_len();
+        }
+        let (fss, offset) = read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
+        current_idx += fss;
+        if current_idx > full_len_without_crc {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: current_idx,
+                expected: full_len_without_crc,
+            }
+            .into());
+        }
+        Ok(Self {
+            pdu_header,
+            segment_metadata,
+            offset,
+            file_data: &buf[current_idx..full_len_without_crc],
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::file_data::{FileDataPdu, RecordContinuationState, SegmentMetadata};
+    use crate::cfdp::pdu::{CommonPduConfig, PduHeader};
+    use crate::cfdp::{SegmentMetadataFlag, SegmentationControl};
+    use crate::util::UbfU8;
+
+    #[test]
+    fn test_basic() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_num = UbfU8::new(3);
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        assert_eq!(fd_pdu.file_data(), file_data);
+        assert_eq!(fd_pdu.offset(), 10);
+        assert!(fd_pdu.segment_metadata().is_none());
+        assert_eq!(
+            fd_pdu.written_len(),
+            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+        );
+    }
+
+    #[test]
+    fn test_serialization() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_num = UbfU8::new(3);
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let mut buf: [u8; 32] = [0; 32];
+        let res = fd_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(
+            written,
+            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+        );
+        let mut current_idx = fd_pdu.pdu_header.header_len();
+        let file_size = u32::from_be_bytes(
+            buf[fd_pdu.pdu_header.header_len()..fd_pdu.pdu_header.header_len() + 4]
+                .try_into()
+                .unwrap(),
+        );
+        current_idx += 4;
+        assert_eq!(file_size, 10);
+        assert_eq!(buf[current_idx], 1);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 2);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 3);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 4);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_num = UbfU8::new(3);
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
+        let mut buf: [u8; 32] = [0; 32];
+        fd_pdu.write_to_bytes(&mut buf).unwrap();
+        let fd_pdu_read_back = FileDataPdu::from_bytes(&buf);
+        assert!(fd_pdu_read_back.is_ok());
+        let fd_pdu_read_back = fd_pdu_read_back.unwrap();
+        assert_eq!(fd_pdu_read_back, fd_pdu);
+    }
+
+    #[test]
+    fn test_with_seg_metadata_serialization() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_num = UbfU8::new(3);
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
+        let pdu_header = PduHeader::new_for_file_data(
+            common_conf,
+            0,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let seg_metadata: [u8; 4] = [4, 3, 2, 1];
+        let segment_meta =
+            SegmentMetadata::new(RecordContinuationState::StartAndEnd, Some(&seg_metadata))
+                .unwrap();
+        let fd_pdu = FileDataPdu::new_with_seg_metadata(pdu_header, segment_meta, 10, &file_data);
+        assert!(fd_pdu.segment_metadata().is_some());
+        assert_eq!(*fd_pdu.segment_metadata().unwrap(), segment_meta);
+        assert_eq!(
+            fd_pdu.written_len(),
+            fd_pdu.pdu_header.header_len()
+                + 1
+                + seg_metadata.len()
+                + core::mem::size_of::<u32>()
+                + 4
+        );
+        let mut buf: [u8; 32] = [0; 32];
+        fd_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing FD PDU failed");
+        let mut current_idx = fd_pdu.pdu_header.header_len();
+        assert_eq!(
+            RecordContinuationState::try_from((buf[current_idx] >> 6) & 0b11).unwrap(),
+            RecordContinuationState::StartAndEnd
+        );
+        assert_eq!((buf[current_idx] & 0b111111) as usize, seg_metadata.len());
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 4);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 3);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 2);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 1);
+        current_idx += 1;
+        // Still verify that the rest is written correctly.
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            10
+        );
+        current_idx += 4;
+        assert_eq!(buf[current_idx], 1);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 2);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 3);
+        current_idx += 1;
+        assert_eq!(buf[current_idx], 4);
+        current_idx += 1;
+        assert_eq!(current_idx, fd_pdu.written_len());
+    }
+
+    #[test]
+    fn test_with_seg_metadata_deserialization() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_num = UbfU8::new(3);
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
+        let pdu_header = PduHeader::new_for_file_data(
+            common_conf,
+            0,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let file_data: [u8; 4] = [1, 2, 3, 4];
+        let seg_metadata: [u8; 4] = [4, 3, 2, 1];
+        let segment_meta =
+            SegmentMetadata::new(RecordContinuationState::StartAndEnd, Some(&seg_metadata))
+                .unwrap();
+        let fd_pdu = FileDataPdu::new_with_seg_metadata(pdu_header, segment_meta, 10, &file_data);
+        let mut buf: [u8; 32] = [0; 32];
+        fd_pdu
+            .write_to_bytes(&mut buf)
+            .expect("writing FD PDU failed");
+        let fd_pdu_read_back = FileDataPdu::from_bytes(&buf);
+        assert!(fd_pdu_read_back.is_ok());
+        let fd_pdu_read_back = fd_pdu_read_back.unwrap();
+        assert_eq!(fd_pdu_read_back, fd_pdu);
+    }
+}

src/cfdp/pdu/finished.rs

@@ -0,0 +1,339 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::{EntityIdTlv, Tlv, TlvType, TlvTypeField};
+use crate::cfdp::{ConditionCode, CrcFlag, PduType, TlvLvError};
+use crate::ByteConversionError;
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum DeliveryCode {
+    Complete = 0,
+    Incomplete = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FileStatus {
+    DiscardDeliberately = 0b00,
+    DiscardedFsRejection = 0b01,
+    Retained = 0b10,
+    Unreported = 0b11,
+}
+
+/// Finished PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FinishedPdu<'fs_responses> {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    delivery_code: DeliveryCode,
+    file_status: FileStatus,
+    fs_responses: Option<&'fs_responses [u8]>,
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl<'fs_responses> FinishedPdu<'fs_responses> {
+    /// Default finished PDU: No error (no fault location field) and no filestore responses.
+    pub fn new_default(
+        pdu_header: PduHeader,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+    ) -> Self {
+        Self::new_generic(
+            pdu_header,
+            ConditionCode::NoError,
+            delivery_code,
+            file_status,
+            None,
+            None,
+        )
+    }
+
+    pub fn new_with_error(
+        pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+        fault_location: EntityIdTlv,
+    ) -> Self {
+        Self::new_generic(
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            None,
+            Some(fault_location),
+        )
+    }
+
+    pub fn new_generic(
+        mut pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+        fs_responses: Option<&'fs_responses [u8]>,
+        fault_location: Option<EntityIdTlv>,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileDirective;
+        let mut finished_pdu = Self {
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            fs_responses,
+            fault_location,
+        };
+        finished_pdu.pdu_header.pdu_datafield_len = finished_pdu.calc_pdu_datafield_len() as u16;
+        finished_pdu
+    }
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn delivery_code(&self) -> DeliveryCode {
+        self.delivery_code
+    }
+
+    pub fn file_status(&self) -> FileStatus {
+        self.file_status
+    }
+
+    pub fn filestore_responses(&self) -> Option<&'fs_responses [u8]> {
+        self.fs_responses
+    }
+
+    pub fn fault_location(&self) -> Option<EntityIdTlv> {
+        self.fault_location
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        let mut base_len = 2;
+        if let Some(fs_responses) = self.fs_responses {
+            base_len += fs_responses.len();
+        }
+        if let Some(fault_location) = self.fault_location {
+            base_len += fault_location.len_full();
+        }
+        base_len
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.written_len();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::FinishedPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = ((self.condition_code as u8) << 4)
+            | ((self.delivery_code as u8) << 2)
+            | self.file_status as u8;
+        current_idx += 1;
+        if let Some(fs_responses) = self.fs_responses {
+            buf[current_idx..current_idx + fs_responses.len()].copy_from_slice(fs_responses);
+            current_idx += fs_responses.len();
+        }
+        if let Some(fault_location) = self.fault_location {
+            current_idx += fault_location.write_to_be_bytes(&mut buf[current_idx..])?;
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    /// Generates [Self] from a raw bytestream.
+    pub fn from_bytes(buf: &'fs_responses [u8]) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let min_expected_len = current_idx + 2;
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::FinishedPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::FinishedPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::FinishedPdu,
+            });
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        // Unwrap is okay here for both of the following operations which can not fail.
+        let delivery_code = DeliveryCode::try_from((buf[current_idx] >> 2) & 0b1).unwrap();
+        let file_status = FileStatus::try_from(buf[current_idx] & 0b11).unwrap();
+        current_idx += 1;
+        let (fs_responses, fault_location) =
+            Self::parse_tlv_fields(current_idx, full_len_without_crc, buf)?;
+        Ok(Self {
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            fs_responses,
+            fault_location,
+        })
+    }
+
+    fn parse_tlv_fields(
+        mut current_idx: usize,
+        full_len_without_crc: usize,
+        buf: &'fs_responses [u8],
+    ) -> Result<(Option<&'fs_responses [u8]>, Option<EntityIdTlv>), PduError> {
+        let mut fs_responses = None;
+        let mut fault_location = None;
+        let start_of_fs_responses = current_idx;
+        // There are leftover filestore response(s) and/or a fault location field.
+        while current_idx < full_len_without_crc {
+            let next_tlv = Tlv::from_bytes(&buf[current_idx..])?;
+            match next_tlv.tlv_type_field() {
+                TlvTypeField::Standard(tlv_type) => {
+                    if tlv_type == TlvType::FilestoreResponse {
+                        current_idx += next_tlv.len_full();
+                        if current_idx == full_len_without_crc {
+                            fs_responses = Some(&buf[start_of_fs_responses..current_idx]);
+                        }
+                    } else if tlv_type == TlvType::EntityId {
+                        // At least one FS response is included.
+                        if current_idx > full_len_without_crc {
+                            fs_responses = Some(&buf[start_of_fs_responses..current_idx]);
+                        }
+                        fault_location = Some(EntityIdTlv::from_bytes(&buf[current_idx..])?);
+                        current_idx += fault_location.as_ref().unwrap().len_full();
+                        // This is considered a configuration error: The entity ID has to be the
+                        // last TLV, everything else would break the whole handling of the packet
+                        // TLVs.
+                        if current_idx != full_len_without_crc {
+                            return Err(PduError::FormatError);
+                        }
+                    } else {
+                        return Err(TlvLvError::InvalidTlvTypeField((tlv_type as u8, None)).into());
+                    }
+                }
+                TlvTypeField::Custom(raw) => {
+                    return Err(TlvLvError::InvalidTlvTypeField((raw, None)).into());
+                }
+            }
+        }
+        Ok((fs_responses, fault_location))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::finished::{DeliveryCode, FileStatus, FinishedPdu};
+    use crate::cfdp::pdu::tests::{common_pdu_conf, verify_raw_header};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
+
+    fn generic_finished_pdu(
+        crc_flag: CrcFlag,
+        fss: LargeFileFlag,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+    ) -> FinishedPdu<'static> {
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        FinishedPdu::new_default(pdu_header, delivery_code, file_status)
+    }
+
+    #[test]
+    fn test_basic() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        assert_eq!(finished_pdu.condition_code(), ConditionCode::NoError);
+        assert_eq!(finished_pdu.delivery_code(), DeliveryCode::Complete);
+        assert_eq!(finished_pdu.file_status(), FileStatus::Retained);
+        assert_eq!(finished_pdu.filestore_responses(), None);
+        assert_eq!(finished_pdu.fault_location(), None);
+        assert_eq!(finished_pdu.pdu_header().pdu_datafield_len, 2);
+    }
+
+    fn generic_serialization_test_no_error(delivery_code: DeliveryCode, file_status: FileStatus) {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            delivery_code,
+            file_status,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let written = finished_pdu.write_to_bytes(&mut buf);
+        assert!(written.is_ok());
+        let written = written.unwrap();
+        assert_eq!(written, finished_pdu.written_len());
+        assert_eq!(written, finished_pdu.pdu_header().header_len() + 2);
+        verify_raw_header(finished_pdu.pdu_header(), &buf);
+        let mut current_idx = finished_pdu.pdu_header().header_len();
+        assert_eq!(buf[current_idx], FileDirectiveType::FinishedPdu as u8);
+        current_idx += 1;
+        assert_eq!(
+            (buf[current_idx] >> 4) & 0b1111,
+            ConditionCode::NoError as u8
+        );
+        assert_eq!((buf[current_idx] >> 2) & 0b1, delivery_code as u8);
+        assert_eq!(buf[current_idx] & 0b11, file_status as u8);
+        assert_eq!(current_idx + 1, written);
+    }
+
+    #[test]
+    fn test_serialization_simple() {
+        generic_serialization_test_no_error(DeliveryCode::Complete, FileStatus::Retained);
+    }
+
+    #[test]
+    fn test_serialization_simple_2() {
+        generic_serialization_test_no_error(
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+        );
+    }
+
+    #[test]
+    fn test_serialization_simple_3() {
+        generic_serialization_test_no_error(DeliveryCode::Incomplete, FileStatus::Unreported);
+    }
+
+    #[test]
+    fn test_deserialization_simple() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        finished_pdu.write_to_bytes(&mut buf).unwrap();
+        let read_back = FinishedPdu::from_bytes(&buf);
+        assert!(read_back.is_ok());
+        let read_back = read_back.unwrap();
+        assert_eq!(finished_pdu, read_back);
+    }
+}

src/cfdp/pdu/metadata.rs

@@ -0,0 +1,534 @@
+use crate::cfdp::lv::Lv;
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::Tlv;
+use crate::cfdp::{ChecksumType, CrcFlag, LargeFileFlag, PduType};
+use crate::ByteConversionError;
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct MetadataGenericParams {
+    pub closure_requested: bool,
+    pub checksum_type: ChecksumType,
+    pub file_size: u64,
+}
+
+impl MetadataGenericParams {
+    pub fn new(closure_requested: bool, checksum_type: ChecksumType, file_size: u64) -> Self {
+        Self {
+            closure_requested,
+            checksum_type,
+            file_size,
+        }
+    }
+}
+
+pub fn build_metadata_opts_from_slice(
+    buf: &mut [u8],
+    tlvs: &[Tlv],
+) -> Result<usize, ByteConversionError> {
+    let mut written = 0;
+    for tlv in tlvs {
+        written += tlv.write_to_bytes(&mut buf[written..])?;
+    }
+    Ok(written)
+}
+
+#[cfg(feature = "alloc")]
+pub fn build_metadata_opts_from_vec(
+    buf: &mut [u8],
+    tlvs: &Vec<Tlv>,
+) -> Result<usize, ByteConversionError> {
+    build_metadata_opts_from_slice(buf, tlvs.as_slice())
+}
+
+/// Helper structure to loop through all options of a metadata PDU. It should be noted that
+/// iterators in Rust are not fallible, but the TLV creation can fail, for example if the raw TLV
+/// data is invalid for some reason. In that case, the iterator will yield [None] because there
+/// is no way to recover from this.
+///
+/// The user can accumulate the length of all TLVs yielded by the iterator and compare it against
+/// the full length of the options to check whether the iterator was able to parse all TLVs
+/// successfully.
+pub struct OptionsIter<'opts> {
+    opt_buf: &'opts [u8],
+    current_idx: usize,
+}
+
+impl<'opts> Iterator for OptionsIter<'opts> {
+    type Item = Tlv<'opts>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_idx == self.opt_buf.len() {
+            return None;
+        }
+        let tlv = Tlv::from_bytes(&self.opt_buf[self.current_idx..]);
+        // There are not really fallible iterators so we can't continue here..
+        if tlv.is_err() {
+            return None;
+        }
+        let tlv = tlv.unwrap();
+        self.current_idx += tlv.len_full();
+        Some(tlv)
+    }
+}
+
+/// Metadata PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.5.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct MetadataPdu<'src_name, 'dest_name, 'opts> {
+    pdu_header: PduHeader,
+    metadata_params: MetadataGenericParams,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    src_file_name: Lv<'src_name>,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    dest_file_name: Lv<'dest_name>,
+    options: Option<&'opts [u8]>,
+}
+
+impl<'src_name, 'dest_name, 'opts> MetadataPdu<'src_name, 'dest_name, 'opts> {
+    pub fn new_no_opts(
+        pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+    ) -> Self {
+        Self::new(
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            None,
+        )
+    }
+
+    pub fn new_with_opts(
+        pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+        options: &'opts [u8],
+    ) -> Self {
+        Self::new(
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            Some(options),
+        )
+    }
+
+    pub fn new(
+        mut pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+        options: Option<&'opts [u8]>,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileDirective;
+        let mut pdu = Self {
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options,
+        };
+        pdu.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    pub fn metadata_params(&self) -> &MetadataGenericParams {
+        &self.metadata_params
+    }
+
+    pub fn src_file_name(&self) -> Lv<'src_name> {
+        self.src_file_name
+    }
+
+    pub fn dest_file_name(&self) -> Lv<'dest_name> {
+        self.dest_file_name
+    }
+
+    pub fn options(&self) -> Option<&'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) -> Option<OptionsIter<'opts>> {
+        self.options?;
+        Some(OptionsIter {
+            opt_buf: self.options.unwrap(),
+            current_idx: 0,
+        })
+    }
+
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        // One directve type octet and one byte of the directive parameter field.
+        let mut len = 2;
+        if self.pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
+            len += 8;
+        } else {
+            len += 4;
+        }
+        len += self.src_file_name.len_full();
+        len += self.dest_file_name.len_full();
+        if let Some(opts) = self.options {
+            len += opts.len();
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.written_len();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: expected_len,
+            }
+            .into());
+        }
+
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::MetadataPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = ((self.metadata_params.closure_requested as u8) << 7)
+            | (self.metadata_params.checksum_type as u8);
+        current_idx += 1;
+        current_idx += write_fss_field(
+            self.pdu_header.common_pdu_conf().file_flag,
+            self.metadata_params.file_size,
+            &mut buf[current_idx..],
+        )?;
+        current_idx += self
+            .src_file_name
+            .write_to_be_bytes(&mut buf[current_idx..])?;
+        current_idx += self
+            .dest_file_name
+            .write_to_be_bytes(&mut buf[current_idx..])?;
+        if let Some(opts) = self.options {
+            buf[current_idx..current_idx + opts.len()].copy_from_slice(opts);
+            current_idx += opts.len();
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes<'longest: 'src_name + 'dest_name + 'opts>(
+        buf: &'longest [u8],
+    ) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let is_large_file = pdu_header.pdu_conf.file_flag == LargeFileFlag::Large;
+        // Minimal length: 1 byte + FSS (4 byte) + 2 empty LV (1 byte)
+        let mut min_expected_len = current_idx + 7;
+        if is_large_file {
+            min_expected_len += 4;
+        }
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::MetadataPdu),
+            }
+        })?;
+        if directive_type != FileDirectiveType::MetadataPdu {
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::MetadataPdu,
+            });
+        }
+        current_idx += 1;
+        let (fss_len, file_size) =
+            read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx + 1..]);
+        let metadata_params = MetadataGenericParams {
+            closure_requested: ((buf[current_idx] >> 6) & 0b1) != 0,
+            checksum_type: ChecksumType::try_from(buf[current_idx] & 0b1111)
+                .map_err(|_| PduError::InvalidChecksumType(buf[current_idx] & 0b1111))?,
+            file_size,
+        };
+        current_idx += 1 + fss_len;
+        let src_file_name = Lv::from_bytes(&buf[current_idx..])?;
+        current_idx += src_file_name.len_full();
+        let dest_file_name = Lv::from_bytes(&buf[current_idx..])?;
+        current_idx += dest_file_name.len_full();
+        // All left-over bytes are options.
+        let mut options = None;
+        if current_idx < full_len_without_crc {
+            options = Some(&buf[current_idx..full_len_without_crc]);
+        }
+        Ok(Self {
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options,
+        })
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::pdu::metadata::{
+        build_metadata_opts_from_slice, build_metadata_opts_from_vec, MetadataGenericParams,
+        MetadataPdu,
+    };
+    use crate::cfdp::pdu::tests::{common_pdu_conf, verify_raw_header};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::tlv::{Tlv, TlvType};
+    use crate::cfdp::{
+        ChecksumType, CrcFlag, LargeFileFlag, PduType, SegmentMetadataFlag, SegmentationControl,
+    };
+    use std::vec;
+
+    const SRC_FILENAME: &'static str = "hello-world.txt";
+    const DEST_FILENAME: &'static str = "hello-world2.txt";
+
+    fn generic_metadata_pdu<'opts>(
+        crc_flag: CrcFlag,
+        fss: LargeFileFlag,
+        opts: Option<&'opts [u8]>,
+    ) -> (
+        Lv<'static>,
+        Lv<'static>,
+        MetadataPdu<'static, 'static, 'opts>,
+    ) {
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        let metadata_params = MetadataGenericParams::new(false, ChecksumType::Crc32, 0x1010);
+        let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
+        let dest_filename =
+            Lv::new_from_str(DEST_FILENAME).expect("Generating destination LV failed");
+        (
+            src_filename,
+            dest_filename,
+            MetadataPdu::new(
+                pdu_header,
+                metadata_params,
+                src_filename,
+                dest_filename,
+                opts,
+            ),
+        )
+    }
+
+    #[test]
+    fn test_basic() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Normal, None);
+        assert_eq!(
+            metadata_pdu.written_len(),
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        assert_eq!(metadata_pdu.src_file_name(), src_filename);
+        assert_eq!(metadata_pdu.dest_file_name(), dest_filename);
+        assert_eq!(metadata_pdu.options(), None);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Normal, None);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        verify_raw_header(metadata_pdu.pdu_header(), &buf);
+        assert_eq!(buf[7], FileDirectiveType::MetadataPdu as u8);
+        assert_eq!(buf[8] >> 6, false as u8);
+        assert_eq!(buf[8] & 0b1111, ChecksumType::Crc32 as u8);
+        assert_eq!(u32::from_be_bytes(buf[9..13].try_into().unwrap()), 0x1010);
+        let mut current_idx = 13;
+        let src_name_from_raw =
+            Lv::from_bytes(&buf[current_idx..]).expect("Creating source name LV failed");
+        assert_eq!(src_name_from_raw, src_filename);
+        current_idx += src_name_from_raw.len_full();
+        let dest_name_from_raw =
+            Lv::from_bytes(&buf[current_idx..]).expect("Creating dest name LV failed");
+        assert_eq!(dest_name_from_raw, dest_filename);
+        current_idx += dest_name_from_raw.len_full();
+        // No options, so no additional data here.
+        assert_eq!(current_idx, written);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let (_, _, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Normal, None);
+        let mut buf: [u8; 64] = [0; 64];
+        metadata_pdu.write_to_bytes(&mut buf).unwrap();
+        let pdu_read_back = MetadataPdu::from_bytes(&buf);
+        assert!(pdu_read_back.is_ok());
+        let pdu_read_back = pdu_read_back.unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+    }
+
+    #[test]
+    fn test_with_crc_flag() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::WithCrc, LargeFileFlag::Normal, None);
+        let mut buf: [u8; 64] = [0; 64];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + core::mem::size_of::<u32>()
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + 2
+        );
+        let pdu_read_back = MetadataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+    }
+
+    #[test]
+    fn test_with_large_file_flag() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Large, None);
+        let mut buf: [u8; 64] = [0; 64];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + core::mem::size_of::<u64>()
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        let pdu_read_back = MetadataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+    }
+
+    #[test]
+    fn test_opts_builders() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_slice = [tlv1, tlv2];
+        let mut buf: [u8; 32] = [0; 32];
+        let opts = build_metadata_opts_from_slice(&mut buf, &tlv_slice);
+        assert!(opts.is_ok());
+        let opts_len = opts.unwrap();
+        assert_eq!(opts_len, tlv1.len_full() + tlv2.len_full());
+        let tlv1_conv_back = Tlv::from_bytes(&buf).unwrap();
+        assert_eq!(tlv1_conv_back, tlv1);
+        let tlv2_conv_back = Tlv::from_bytes(&buf[tlv1_conv_back.len_full()..]).unwrap();
+        assert_eq!(tlv2_conv_back, tlv2);
+    }
+
+    #[test]
+    fn test_opts_builders_from_vec() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_vec = vec![tlv1, tlv2];
+        let mut buf: [u8; 32] = [0; 32];
+        let opts = build_metadata_opts_from_vec(&mut buf, &tlv_vec);
+        assert!(opts.is_ok());
+        let opts_len = opts.unwrap();
+        assert_eq!(opts_len, tlv1.len_full() + tlv2.len_full());
+        let tlv1_conv_back = Tlv::from_bytes(&buf).unwrap();
+        assert_eq!(tlv1_conv_back, tlv1);
+        let tlv2_conv_back = Tlv::from_bytes(&buf[tlv1_conv_back.len_full()..]).unwrap();
+        assert_eq!(tlv2_conv_back, tlv2);
+    }
+
+    #[test]
+    fn test_with_opts() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_vec = vec![tlv1, tlv2];
+        let mut opts_buf: [u8; 32] = [0; 32];
+        let opts_len = build_metadata_opts_from_vec(&mut opts_buf, &tlv_vec).unwrap();
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            Some(&opts_buf[..opts_len]),
+        );
+        let mut buf: [u8; 128] = [0; 128];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + opts_len
+        );
+        let pdu_read_back = MetadataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+        let opts_iter = pdu_read_back.options_iter();
+        assert!(opts_iter.is_some());
+        let opts_iter = opts_iter.unwrap();
+        let mut accumulated_len = 0;
+        for (idx, opt) in opts_iter.enumerate() {
+            assert_eq!(tlv_vec[idx], opt);
+            accumulated_len += opt.len_full();
+        }
+        assert_eq!(accumulated_len, pdu_read_back.options().unwrap().len());
+    }
+
+    #[test]
+    fn test_corrects_pdu_header() {
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        );
+        let metadata_params = MetadataGenericParams::new(false, ChecksumType::Crc32, 10);
+        let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
+        let dest_filename =
+            Lv::new_from_str(DEST_FILENAME).expect("Generating destination LV failed");
+        let metadata_pdu =
+            MetadataPdu::new_no_opts(pdu_header, metadata_params, src_filename, dest_filename);
+        assert_eq!(metadata_pdu.pdu_header().pdu_type(), PduType::FileDirective);
+    }
+}

src/cfdp/pdu/mod.rs

@@ -0,0 +1,995 @@
+//! CFDP Packet Data Unit (PDU) support.
+use crate::cfdp::*;
+use crate::util::{UnsignedByteField, UnsignedByteFieldU8, UnsignedEnum};
+use crate::ByteConversionError;
+use crate::CRC_CCITT_FALSE;
+use core::fmt::{Display, Formatter};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub mod eof;
+pub mod file_data;
+pub mod finished;
+pub mod metadata;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FileDirectiveType {
+    EofPdu = 0x04,
+    FinishedPdu = 0x05,
+    AckPdu = 0x06,
+    MetadataPdu = 0x07,
+    NakPdu = 0x08,
+    PromptPdu = 0x09,
+    KeepAlivePdu = 0x0c,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum PduError {
+    ByteConversionError(ByteConversionError),
+    /// Found version ID invalid, not equal to [CFDP_VERSION_2].
+    CfdpVersionMissmatch(u8),
+    /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    InvalidEntityLen(u8),
+    /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    InvalidTransactionSeqNumLen(u8),
+    SourceDestIdLenMissmatch {
+        src_id_len: usize,
+        dest_id_len: usize,
+    },
+    WrongDirectiveType {
+        found: FileDirectiveType,
+        expected: FileDirectiveType,
+    },
+    /// The directive type field contained a value not in the range of permitted values.
+    InvalidDirectiveType {
+        found: u8,
+        expected: Option<FileDirectiveType>,
+    },
+    /// Invalid condition code. Contains the raw detected value.
+    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/).
+    InvalidChecksumType(u8),
+    FileSizeTooLarge(u64),
+    /// If the CRC flag for a PDU is enabled and the checksum check fails. Contains raw 16-bit CRC.
+    ChecksumError(u16),
+    /// Generic error for invalid PDU formats.
+    FormatError,
+    /// Error handling a TLV field.
+    TlvLvError(TlvLvError),
+}
+
+impl Display for PduError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            PduError::InvalidEntityLen(raw_id) => {
+                write!(
+                    f,
+                    "Invalid PDU entity ID length {raw_id}, only [1, 2, 4, 8] are allowed"
+                )
+            }
+            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::ByteConversionError(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::ByteConversionError(e) => Some(e),
+            PduError::TlvLvError(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl From<ByteConversionError> for PduError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl From<TlvLvError> for PduError {
+    fn from(e: TlvLvError) -> Self {
+        Self::TlvLvError(e)
+    }
+}
+
+/// Common configuration fields for a PDU.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct CommonPduConfig {
+    source_entity_id: UnsignedByteField,
+    dest_entity_id: UnsignedByteField,
+    pub transaction_seq_num: UnsignedByteField,
+    pub trans_mode: TransmissionMode,
+    pub file_flag: LargeFileFlag,
+    pub crc_flag: CrcFlag,
+    pub direction: Direction,
+}
+
+// TODO: Builder pattern might be applicable here..
+impl CommonPduConfig {
+    pub fn new(
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+        transaction_seq_num: impl Into<UnsignedByteField>,
+        trans_mode: TransmissionMode,
+        file_flag: LargeFileFlag,
+        crc_flag: CrcFlag,
+        direction: Direction,
+    ) -> Result<Self, PduError> {
+        let (source_id, dest_id) = Self::source_dest_id_check(source_id, dest_id)?;
+        let transaction_seq_num = transaction_seq_num.into();
+        if transaction_seq_num.size() != 1
+            && transaction_seq_num.size() != 2
+            && transaction_seq_num.size() != 4
+            && transaction_seq_num.size() != 8
+        {
+            return Err(PduError::InvalidTransactionSeqNumLen(
+                transaction_seq_num.size() as u8,
+            ));
+        }
+        Ok(Self {
+            source_entity_id: source_id,
+            dest_entity_id: dest_id,
+            transaction_seq_num,
+            trans_mode,
+            file_flag,
+            crc_flag,
+            direction,
+        })
+    }
+
+    pub fn new_with_byte_fields(
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+        transaction_seq_num: impl Into<UnsignedByteField>,
+    ) -> Result<Self, PduError> {
+        Self::new(
+            source_id,
+            dest_id,
+            transaction_seq_num,
+            TransmissionMode::Acknowledged,
+            LargeFileFlag::Normal,
+            CrcFlag::NoCrc,
+            Direction::TowardsReceiver,
+        )
+    }
+
+    pub fn source_id(&self) -> UnsignedByteField {
+        self.source_entity_id
+    }
+
+    fn source_dest_id_check(
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+    ) -> Result<(UnsignedByteField, UnsignedByteField), PduError> {
+        let source_id = source_id.into();
+        let dest_id = dest_id.into();
+        if source_id.size() != dest_id.size() {
+            return Err(PduError::SourceDestIdLenMissmatch {
+                src_id_len: source_id.size(),
+                dest_id_len: dest_id.size(),
+            });
+        }
+        if source_id.size() != 1
+            && source_id.size() != 2
+            && source_id.size() != 4
+            && source_id.size() != 8
+        {
+            return Err(PduError::InvalidEntityLen(source_id.size() as u8));
+        }
+        Ok((source_id, dest_id))
+    }
+
+    pub fn set_source_and_dest_id(
+        &mut self,
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+    ) -> Result<(), PduError> {
+        let (source_id, dest_id) = Self::source_dest_id_check(source_id, dest_id)?;
+        self.source_entity_id = source_id;
+        self.dest_entity_id = dest_id;
+        Ok(())
+    }
+
+    pub fn dest_id(&self) -> UnsignedByteField {
+        self.dest_entity_id
+    }
+}
+
+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
+    fn default() -> Self {
+        // The new function can not fail for these input parameters.
+        Self::new(
+            UnsignedByteFieldU8::new(0),
+            UnsignedByteFieldU8::new(0),
+            UnsignedByteFieldU8::new(0),
+            TransmissionMode::Acknowledged,
+            LargeFileFlag::Normal,
+            CrcFlag::NoCrc,
+            Direction::TowardsReceiver,
+        )
+        .unwrap()
+    }
+}
+
+pub const FIXED_HEADER_LEN: usize = 4;
+
+/// Abstraction for the PDU header common to all CFDP PDUs.
+///
+/// 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))]
+pub struct PduHeader {
+    pdu_type: PduType,
+    pdu_conf: CommonPduConfig,
+    seg_metadata_flag: SegmentMetadataFlag,
+    seg_ctrl: SegmentationControl,
+    pdu_datafield_len: u16,
+}
+
+impl PduHeader {
+    pub fn new_for_file_data(
+        pdu_conf: CommonPduConfig,
+        pdu_datafield_len: u16,
+        seg_metadata_flag: SegmentMetadataFlag,
+        seg_ctrl: SegmentationControl,
+    ) -> Self {
+        Self::new_generic(
+            PduType::FileData,
+            pdu_conf,
+            pdu_datafield_len,
+            seg_metadata_flag,
+            seg_ctrl,
+        )
+    }
+
+    pub fn new_for_file_data_default(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
+        Self::new_generic(
+            PduType::FileData,
+            pdu_conf,
+            pdu_datafield_len,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        )
+    }
+    pub fn new_no_file_data(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
+        Self::new_generic(
+            PduType::FileDirective,
+            pdu_conf,
+            pdu_datafield_len,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        )
+    }
+
+    pub fn new_generic(
+        pdu_type: PduType,
+        pdu_conf: CommonPduConfig,
+        pdu_datafield_len: u16,
+        seg_metadata_flag: SegmentMetadataFlag,
+        seg_ctrl: SegmentationControl,
+    ) -> Self {
+        Self {
+            pdu_type,
+            pdu_conf,
+            seg_metadata_flag,
+            seg_ctrl,
+            pdu_datafield_len,
+        }
+    }
+
+    /// Returns only the length of the PDU header when written to a raw buffer.
+    pub fn header_len(&self) -> usize {
+        FIXED_HEADER_LEN
+            + self.pdu_conf.source_entity_id.size()
+            + self.pdu_conf.transaction_seq_num.size()
+            + self.pdu_conf.dest_entity_id.size()
+    }
+
+    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.
+    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> {
+        // Internal note: There is currently no way to pass a PDU configuration like this, but
+        // this check is still kept for defensive programming.
+        if self.pdu_conf.source_entity_id.size() != self.pdu_conf.dest_entity_id.size() {
+            return Err(PduError::SourceDestIdLenMissmatch {
+                src_id_len: self.pdu_conf.source_entity_id.size(),
+                dest_id_len: self.pdu_conf.dest_entity_id.size(),
+            });
+        }
+        if buf.len()
+            < FIXED_HEADER_LEN
+                + self.pdu_conf.source_entity_id.size()
+                + self.pdu_conf.transaction_seq_num.size()
+        {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: FIXED_HEADER_LEN,
+            }
+            .into());
+        }
+        let mut current_idx = 0;
+        buf[current_idx] = (CFDP_VERSION_2 << 5)
+            | ((self.pdu_type as u8) << 4)
+            | ((self.pdu_conf.direction as u8) << 3)
+            | ((self.pdu_conf.trans_mode as u8) << 2)
+            | ((self.pdu_conf.crc_flag as u8) << 1)
+            | (self.pdu_conf.file_flag as u8);
+        current_idx += 1;
+        buf[current_idx..current_idx + 2].copy_from_slice(&self.pdu_datafield_len.to_be_bytes());
+        current_idx += 2;
+        buf[current_idx] = ((self.seg_ctrl as u8) << 7)
+            | (((self.pdu_conf.source_entity_id.size() - 1) as u8) << 4)
+            | ((self.seg_metadata_flag as u8) << 3)
+            | ((self.pdu_conf.transaction_seq_num.size() - 1) as u8);
+        current_idx += 1;
+        self.pdu_conf.source_entity_id.write_to_be_bytes(
+            &mut buf[current_idx..current_idx + self.pdu_conf.source_entity_id.size()],
+        )?;
+        current_idx += self.pdu_conf.source_entity_id.size();
+        self.pdu_conf.transaction_seq_num.write_to_be_bytes(
+            &mut buf[current_idx..current_idx + self.pdu_conf.transaction_seq_num.size()],
+        )?;
+        current_idx += self.pdu_conf.transaction_seq_num.size();
+        self.pdu_conf.dest_entity_id.write_to_be_bytes(
+            &mut buf[current_idx..current_idx + self.pdu_conf.dest_entity_id.size()],
+        )?;
+        current_idx += self.pdu_conf.dest_entity_id.size();
+        Ok(current_idx)
+    }
+
+    /// This function first verifies that the buffer can hold the full length of the PDU parsed from
+    /// the header. Then, it verifies the checksum as specified in the standard if the CRC flag
+    /// of the PDU header is set.
+    ///
+    /// This function will return the PDU length excluding the 2 CRC bytes on success. If the CRC
+    /// flag is not set, it will simply return the PDU length.
+    pub fn verify_length_and_checksum(&self, buf: &[u8]) -> Result<usize, PduError> {
+        if buf.len() < self.pdu_len() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: self.pdu_len(),
+            }
+            .into());
+        }
+        if self.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            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(
+                    buf[self.pdu_len() - 2..self.pdu_len()].try_into().unwrap(),
+                )));
+            }
+            return Ok(self.pdu_len() - 2);
+        }
+        Ok(self.pdu_len())
+    }
+
+    /// Please note that this function will not verify that the passed buffer can hold the full
+    /// PDU length. This allows recovering the header portion even if the data field length is
+    /// invalid. This function will also not do the CRC procedure specified in chapter 4.1.1
+    /// and 4.1.2 because performing the CRC procedure requires the buffer to be large enough
+    /// to hold the full PDU.
+    ///
+    /// Both functions can however be performed with the [Self::verify_length_and_checksum]
+    /// function.
+    pub fn from_bytes(buf: &[u8]) -> Result<(Self, usize), PduError> {
+        if buf.len() < FIXED_HEADER_LEN {
+            return Err(PduError::ByteConversionError(
+                ByteConversionError::FromSliceTooSmall {
+                    found: buf.len(),
+                    expected: FIXED_HEADER_LEN,
+                },
+            ));
+        }
+        let cfdp_version_raw = (buf[0] >> 5) & 0b111;
+        if cfdp_version_raw != CFDP_VERSION_2 {
+            return Err(PduError::CfdpVersionMissmatch(cfdp_version_raw));
+        }
+        // unwrap for single bit fields: This operation will always succeed.
+        let pdu_type = PduType::try_from((buf[0] >> 4) & 0b1).unwrap();
+        let direction = Direction::try_from((buf[0] >> 3) & 0b1).unwrap();
+        let trans_mode = TransmissionMode::try_from((buf[0] >> 2) & 0b1).unwrap();
+        let crc_flag = CrcFlag::try_from((buf[0] >> 1) & 0b1).unwrap();
+        let file_flag = LargeFileFlag::try_from(buf[0] & 0b1).unwrap();
+        let pdu_datafield_len = u16::from_be_bytes(buf[1..3].try_into().unwrap());
+        let seg_ctrl = SegmentationControl::try_from((buf[3] >> 7) & 0b1).unwrap();
+        let expected_len_entity_ids = (((buf[3] >> 4) & 0b111) + 1) as usize;
+        if (expected_len_entity_ids != 1)
+            && (expected_len_entity_ids != 2)
+            && (expected_len_entity_ids != 4)
+            && (expected_len_entity_ids != 8)
+        {
+            return Err(PduError::InvalidEntityLen(expected_len_entity_ids as u8));
+        }
+        let seg_metadata_flag = SegmentMetadataFlag::try_from((buf[3] >> 3) & 0b1).unwrap();
+        let expected_len_seq_num = ((buf[3] & 0b111) + 1) as usize;
+        if (expected_len_seq_num != 1)
+            && (expected_len_seq_num != 2)
+            && (expected_len_seq_num != 4)
+            && (expected_len_seq_num != 8)
+        {
+            return Err(PduError::InvalidTransactionSeqNumLen(
+                expected_len_seq_num as u8,
+            ));
+        }
+        if buf.len() < (4 + 2 * expected_len_entity_ids + expected_len_seq_num) {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 4 + 2 * expected_len_entity_ids + expected_len_seq_num,
+            }
+            .into());
+        }
+        let mut current_idx = 4;
+        // It is okay to unwrap here because we checked the validity of the expected length and of
+        // the remaining buffer length.
+        let source_id =
+            UnsignedByteField::new_from_be_bytes(expected_len_entity_ids, &buf[current_idx..])
+                .unwrap();
+        current_idx += expected_len_entity_ids;
+        let transaction_seq_num =
+            UnsignedByteField::new_from_be_bytes(expected_len_seq_num, &buf[current_idx..])
+                .unwrap();
+        current_idx += expected_len_seq_num;
+        let dest_id =
+            UnsignedByteField::new_from_be_bytes(expected_len_entity_ids, &buf[current_idx..])
+                .unwrap();
+        current_idx += expected_len_entity_ids;
+        let common_pdu_conf = CommonPduConfig::new(
+            source_id,
+            dest_id,
+            transaction_seq_num,
+            trans_mode,
+            file_flag,
+            crc_flag,
+            direction,
+        )
+        .unwrap();
+        Ok((
+            PduHeader {
+                pdu_type,
+                pdu_conf: common_pdu_conf,
+                seg_metadata_flag,
+                seg_ctrl,
+                pdu_datafield_len,
+            },
+            current_idx,
+        ))
+    }
+    pub fn pdu_type(&self) -> PduType {
+        self.pdu_type
+    }
+
+    pub fn common_pdu_conf(&self) -> &CommonPduConfig {
+        &self.pdu_conf
+    }
+
+    pub fn seg_metadata_flag(&self) -> SegmentMetadataFlag {
+        self.seg_metadata_flag
+    }
+    pub fn seg_ctrl(&self) -> SegmentationControl {
+        self.seg_ctrl
+    }
+}
+
+pub(crate) fn write_fss_field(
+    file_flag: LargeFileFlag,
+    file_size: u64,
+    buf: &mut [u8],
+) -> Result<usize, PduError> {
+    Ok(if file_flag == LargeFileFlag::Large {
+        buf[..core::mem::size_of::<u64>()].copy_from_slice(&file_size.to_be_bytes());
+        core::mem::size_of::<u64>()
+    } else {
+        if file_size > u32::MAX as u64 {
+            return Err(PduError::FileSizeTooLarge(file_size));
+        }
+        buf[..core::mem::size_of::<u32>()].copy_from_slice(&(file_size as u32).to_be_bytes());
+        core::mem::size_of::<u32>()
+    })
+}
+
+pub(crate) fn read_fss_field(file_flag: LargeFileFlag, buf: &[u8]) -> (usize, u64) {
+    if file_flag == LargeFileFlag::Large {
+        (
+            core::mem::size_of::<u64>(),
+            u64::from_be_bytes(buf[..core::mem::size_of::<u64>()].try_into().unwrap()),
+        )
+    } else {
+        (
+            core::mem::size_of::<u32>(),
+            u32::from_be_bytes(buf[..core::mem::size_of::<u32>()].try_into().unwrap()).into(),
+        )
+    }
+}
+
+// This is a generic length check applicable to most PDU deserializations. It first checks whether
+// a given buffer can hold an expected minimum size, and then it checks whether the PDU datafield
+// length is larger than that expected minimum size.
+pub(crate) fn generic_length_checks_pdu_deserialization(
+    buf: &[u8],
+    min_expected_len: usize,
+    full_len_without_crc: usize,
+) -> Result<(), ByteConversionError> {
+    // Buffer too short to hold additional expected minimum datasize.
+    if buf.len() < min_expected_len {
+        return Err(ByteConversionError::FromSliceTooSmall {
+            found: buf.len(),
+            expected: min_expected_len,
+        });
+    }
+    // This can happen if the PDU datafield length value is invalid.
+    if full_len_without_crc < min_expected_len {
+        return Err(ByteConversionError::FromSliceTooSmall {
+            found: full_len_without_crc,
+            expected: min_expected_len,
+        });
+    }
+    Ok(())
+}
+
+pub(crate) fn add_pdu_crc(buf: &mut [u8], mut current_idx: usize) -> usize {
+    let mut digest = CRC_CCITT_FALSE.digest();
+    digest.update(&buf[..current_idx]);
+    buf[current_idx..current_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+    current_idx += 2;
+    current_idx
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::{CommonPduConfig, PduError, PduHeader, FIXED_HEADER_LEN};
+    use crate::cfdp::{
+        CrcFlag, Direction, LargeFileFlag, PduType, SegmentMetadataFlag, SegmentationControl,
+        TransmissionMode, CFDP_VERSION_2,
+    };
+    use crate::util::{
+        UbfU8, UnsignedByteField, UnsignedByteFieldU16, UnsignedByteFieldU8, UnsignedEnum,
+    };
+    use crate::ByteConversionError;
+    use std::format;
+
+    pub(crate) fn common_pdu_conf(crc_flag: CrcFlag, fss: LargeFileFlag) -> CommonPduConfig {
+        let src_id = UbfU8::new(5);
+        let dest_id = UbfU8::new(10);
+        let transaction_seq_num = UbfU8::new(20);
+        let mut pdu_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num)
+                .expect("Generating common PDU config");
+        pdu_conf.crc_flag = crc_flag;
+        pdu_conf.file_flag = fss;
+        pdu_conf
+    }
+
+    pub(crate) fn verify_raw_header(pdu_conf: &PduHeader, buf: &[u8]) {
+        assert_eq!((buf[0] >> 5) & 0b111, CFDP_VERSION_2);
+        // File directive
+        assert_eq!((buf[0] >> 4) & 1, pdu_conf.pdu_type as u8);
+        // Towards receiver
+        assert_eq!((buf[0] >> 3) & 1, pdu_conf.pdu_conf.direction as u8);
+        // Acknowledged
+        assert_eq!((buf[0] >> 2) & 1, pdu_conf.pdu_conf.trans_mode as u8);
+        // No CRC
+        assert_eq!((buf[0] >> 1) & 1, pdu_conf.pdu_conf.crc_flag as u8);
+        // Regular file size
+        assert_eq!(buf[0] & 1, pdu_conf.pdu_conf.file_flag as u8);
+        let pdu_datafield_len = u16::from_be_bytes(buf[1..3].try_into().unwrap());
+        assert_eq!(pdu_datafield_len, pdu_conf.pdu_datafield_len);
+        // No record boundary preservation
+        assert_eq!((buf[3] >> 7) & 1, pdu_conf.seg_ctrl as u8);
+        // Entity ID length raw value is actual number of octets - 1 => 0
+        let entity_id_len = pdu_conf.pdu_conf.source_entity_id.size();
+        assert_eq!((buf[3] >> 4) & 0b111, entity_id_len as u8 - 1);
+        // No segment metadata
+        assert_eq!((buf[3] >> 3) & 0b1, pdu_conf.seg_metadata_flag as u8);
+        // Transaction Sequence ID length raw value is actual number of octets - 1 => 0
+        let seq_num_len = pdu_conf.pdu_conf.transaction_seq_num.size();
+        assert_eq!(buf[3] & 0b111, seq_num_len as u8 - 1);
+        let mut current_idx = 4;
+        let mut byte_field_check = |field_len: usize, ubf: &UnsignedByteField| {
+            match field_len {
+                1 => assert_eq!(buf[current_idx], ubf.value() as u8),
+                2 => assert_eq!(
+                    u16::from_be_bytes(
+                        buf[current_idx..current_idx + field_len]
+                            .try_into()
+                            .unwrap()
+                    ),
+                    ubf.value() as u16
+                ),
+                4 => assert_eq!(
+                    u32::from_be_bytes(
+                        buf[current_idx..current_idx + field_len]
+                            .try_into()
+                            .unwrap()
+                    ),
+                    ubf.value() as u32
+                ),
+                8 => assert_eq!(
+                    u64::from_be_bytes(
+                        buf[current_idx..current_idx + field_len]
+                            .try_into()
+                            .unwrap()
+                    ),
+                    ubf.value() as u64
+                ),
+                _ => panic!("invalid entity ID length"),
+            }
+            current_idx += field_len
+        };
+        byte_field_check(entity_id_len, &pdu_conf.pdu_conf.source_entity_id);
+        byte_field_check(seq_num_len, &pdu_conf.pdu_conf.transaction_seq_num);
+        byte_field_check(entity_id_len, &pdu_conf.pdu_conf.dest_entity_id);
+    }
+
+    #[test]
+    fn test_basic_state() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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);
+        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);
+        // These should be 0 and ignored for non-filedata PDUs
+        assert_eq!(
+            pdu_header.seg_metadata_flag(),
+            SegmentMetadataFlag::NotPresent
+        );
+        assert_eq!(
+            pdu_header.seg_ctrl(),
+            SegmentationControl::NoRecordBoundaryPreservation
+        );
+        assert_eq!(pdu_header.pdu_datafield_len, 5);
+        assert_eq!(pdu_header.header_len(), 7);
+    }
+
+    #[test]
+    fn test_basic_state_default() {
+        let default_conf = CommonPduConfig::default();
+        assert_eq!(default_conf.source_id(), UnsignedByteFieldU8::new(0).into());
+        assert_eq!(default_conf.dest_id(), UnsignedByteFieldU8::new(0).into());
+        assert_eq!(
+            default_conf.transaction_seq_num,
+            UnsignedByteFieldU8::new(0).into()
+        );
+        assert_eq!(default_conf.trans_mode, TransmissionMode::Acknowledged);
+        assert_eq!(default_conf.direction, Direction::TowardsReceiver);
+        assert_eq!(default_conf.crc_flag, CrcFlag::NoCrc);
+        assert_eq!(default_conf.file_flag, LargeFileFlag::Normal);
+    }
+
+    #[test]
+    fn test_pdu_header_setter() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let mut common_pdu_cfg =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
+                .expect("common config creation failed");
+        let other_src_id = UnsignedByteFieldU16::new(5);
+        let other_dest_id = UnsignedByteFieldU16::new(6);
+        let set_result = common_pdu_cfg.set_source_and_dest_id(other_src_id, other_dest_id);
+        assert!(set_result.is_ok());
+        assert_eq!(common_pdu_cfg.source_id(), other_src_id.into());
+        assert_eq!(common_pdu_cfg.dest_id(), other_dest_id.into());
+    }
+
+    #[test]
+    fn test_serialization_1() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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 mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        // 4 byte fixed header plus three bytes src, dest ID and transaction ID
+        assert_eq!(res.unwrap(), 7);
+        verify_raw_header(&pdu_header, &buf);
+    }
+
+    #[test]
+    fn test_deserialization_1() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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 mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let deser_res = PduHeader::from_bytes(&buf);
+        assert!(deser_res.is_ok());
+        let (header_read_back, read_size) = deser_res.unwrap();
+        assert_eq!(read_size, 7);
+        assert_eq!(header_read_back, pdu_header);
+    }
+
+    #[test]
+    fn test_serialization_2() {
+        let src_id = UnsignedByteFieldU16::new(0x0001);
+        let dest_id = UnsignedByteFieldU16::new(0x0203);
+        let transaction_id = UnsignedByteFieldU16::new(0x0405);
+        let mut common_pdu_cfg =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
+                .expect("common config creation failed");
+        common_pdu_cfg.crc_flag = CrcFlag::WithCrc;
+        common_pdu_cfg.direction = Direction::TowardsSender;
+        common_pdu_cfg.trans_mode = TransmissionMode::Unacknowledged;
+        common_pdu_cfg.file_flag = LargeFileFlag::Large;
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_cfg,
+            5,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        assert_eq!(pdu_header.header_len(), 10);
+        let mut buf: [u8; 16] = [0; 16];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok(), "{}", format!("Result {res:?} not okay"));
+        // 4 byte fixed header, 6 bytes additional fields
+        assert_eq!(res.unwrap(), 10);
+        verify_raw_header(&pdu_header, &buf);
+    }
+
+    #[test]
+    fn test_deserialization_2() {
+        let src_id = UnsignedByteFieldU16::new(0x0001);
+        let dest_id = UnsignedByteFieldU16::new(0x0203);
+        let transaction_id = UnsignedByteFieldU16::new(0x0405);
+        let mut common_pdu_cfg =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
+                .expect("common config creation failed");
+        common_pdu_cfg.crc_flag = CrcFlag::WithCrc;
+        common_pdu_cfg.direction = Direction::TowardsSender;
+        common_pdu_cfg.trans_mode = TransmissionMode::Unacknowledged;
+        common_pdu_cfg.file_flag = LargeFileFlag::Large;
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_cfg,
+            5,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let mut buf: [u8; 16] = [0; 16];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let deser_res = PduHeader::from_bytes(&buf);
+        assert!(deser_res.is_ok());
+        let (header_read_back, read_size) = deser_res.unwrap();
+        assert_eq!(read_size, 10);
+        assert_eq!(header_read_back, pdu_header);
+    }
+
+    #[test]
+    fn test_invalid_raw_version() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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 mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        buf[0] &= !0b1110_0000;
+        buf[0] |= (CFDP_VERSION_2 + 1) << 5;
+        let res = PduHeader::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let PduError::CfdpVersionMissmatch(raw_version) = error {
+            assert_eq!(raw_version, CFDP_VERSION_2 + 1);
+        } else {
+            panic!("invalid exception: {}", error);
+        }
+    }
+
+    #[test]
+    fn test_buf_too_small_1() {
+        let buf: [u8; 3] = [0; 3];
+        let res = PduHeader::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall {
+            found,
+            expected,
+        }) = error
+        {
+            assert_eq!(found, 3);
+            assert_eq!(expected, FIXED_HEADER_LEN);
+        } else {
+            panic!("invalid exception: {}", error);
+        }
+    }
+
+    #[test]
+    fn test_buf_too_small_2() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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 mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let header = PduHeader::from_bytes(&buf[0..6]);
+        assert!(header.is_err());
+        let error = header.unwrap_err();
+        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall {
+            found,
+            expected,
+        }) = error
+        {
+            assert_eq!(found, 6);
+            assert_eq!(expected, 7);
+        }
+    }
+
+    #[test]
+    fn test_invalid_seq_len() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_id = UbfU8::new(3);
+        let invalid_byte_field = UnsignedByteField::new(3, 5);
+        let pdu_conf_res =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, invalid_byte_field);
+        assert!(pdu_conf_res.is_err());
+        let error = pdu_conf_res.unwrap_err();
+        if let PduError::InvalidTransactionSeqNumLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("Invalid exception: {}", error)
+        }
+        let pdu_conf_res = CommonPduConfig::new_with_byte_fields(
+            invalid_byte_field,
+            invalid_byte_field,
+            transaction_seq_id,
+        );
+        assert!(pdu_conf_res.is_err());
+        let error = pdu_conf_res.unwrap_err();
+        if let PduError::InvalidEntityLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("Invalid exception: {}", error)
+        }
+    }
+    #[test]
+    fn test_missmatch_src_dest_id() {
+        let src_id = UnsignedByteField::new(1, 5);
+        let dest_id = UnsignedByteField::new(2, 5);
+        let transaction_seq_id = UbfU8::new(3);
+        let pdu_conf_res =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_id);
+        assert!(pdu_conf_res.is_err());
+        let error = pdu_conf_res.unwrap_err();
+        if let PduError::SourceDestIdLenMissmatch {
+            src_id_len,
+            dest_id_len,
+        } = error
+        {
+            assert_eq!(src_id_len, 1);
+            assert_eq!(dest_id_len, 2);
+        }
+    }
+
+    #[test]
+    fn test_invalid_raw_src_id_len() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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 mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        buf[3] &= !0b0111_0000;
+        // Equivalent to the length of three
+        buf[3] |= 0b10 << 4;
+        let header_res = PduHeader::from_bytes(&buf);
+        assert!(header_res.is_err());
+        let error = header_res.unwrap_err();
+        if let PduError::InvalidEntityLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+
+    #[test]
+    fn test_invalid_transaction_seq_id_len() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        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 mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        buf[3] &= !0b0000_0111;
+        // Equivalent to the length of three
+        buf[3] |= 0b10;
+        let header_res = PduHeader::from_bytes(&buf);
+        assert!(header_res.is_err());
+        let error = header_res.unwrap_err();
+        if let PduError::InvalidTransactionSeqNumLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+}

src/cfdp/tlv/mod.rs

@@ -0,0 +1,798 @@
+//! Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
+use crate::cfdp::lv::{
+    generic_len_check_data_serialization, generic_len_check_deserialization, Lv, MIN_LV_LEN,
+};
+use crate::cfdp::TlvLvError;
+use crate::util::{UnsignedByteField, UnsignedByteFieldError, UnsignedEnum};
+use crate::ByteConversionError;
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+pub mod msg_to_user;
+
+pub const MIN_TLV_LEN: usize = 2;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum TlvType {
+    FilestoreRequest = 0x00,
+    FilestoreResponse = 0x01,
+    MsgToUser = 0x02,
+    FaultHandler = 0x04,
+    FlowLabel = 0x05,
+    EntityId = 0x06,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum TlvTypeField {
+    Standard(TlvType),
+    Custom(u8),
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FilestoreActionCode {
+    CreateFile = 0b0000,
+    DeleteFile = 0b0001,
+    RenameFile = 0b0010,
+    /// This operation appends one file to another. The first specified name will form the first
+    /// part of the new file and the name of the new file. This function can be used to get
+    /// similar functionality to the UNIX cat utility (albeit for only two files).
+    AppendFile = 0b0011,
+    /// This operation replaces the content of the first specified file with the content of
+    /// the secondly specified file.
+    ReplaceFile = 0b0100,
+    CreateDirectory = 0b0101,
+    RemoveDirectory = 0b0110,
+    DenyFile = 0b0111,
+    DenyDirectory = 0b1000,
+}
+
+impl From<u8> for TlvTypeField {
+    fn from(value: u8) -> Self {
+        match TlvType::try_from(value) {
+            Ok(tlv_type) => TlvTypeField::Standard(tlv_type),
+            Err(_) => TlvTypeField::Custom(value),
+        }
+    }
+}
+
+impl From<TlvTypeField> for u8 {
+    fn from(value: TlvTypeField) -> Self {
+        match value {
+            TlvTypeField::Standard(std) => std as u8,
+            TlvTypeField::Custom(custom) => custom,
+        }
+    }
+}
+
+/// Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
+///
+/// Please note that this class is zero-copy and does not generate a copy of the value data for
+/// both the regular [Self::new] constructor and the [Self::from_bytes] constructor.
+///
+/// # Lifetimes
+///  * `data`: If the TLV is generated from a raw bytestream, this will be the lifetime of
+///    the raw bytestream. If the TLV is generated from a raw slice or a similar data reference,
+///    this will be the lifetime of that data reference.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct Tlv<'data> {
+    tlv_type_field: TlvTypeField,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    lv: Lv<'data>,
+}
+
+impl<'data> Tlv<'data> {
+    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvError> {
+        Ok(Tlv {
+            tlv_type_field: TlvTypeField::Standard(tlv_type),
+            lv: Lv::new(data)?,
+        })
+    }
+
+    /// Creates a TLV with an empty value field.
+    pub fn new_empty(tlv_type: TlvType) -> Tlv<'data> {
+        Tlv {
+            tlv_type_field: TlvTypeField::Standard(tlv_type),
+            lv: Lv::new_empty(),
+        }
+    }
+
+    /// Checks whether the type field contains one of the standard types specified in the CFDP
+    /// standard and is part of the [TlvType] enum.
+    pub fn is_standard_tlv(&self) -> bool {
+        if let TlvTypeField::Standard(_) = self.tlv_type_field {
+            return true;
+        }
+        false
+    }
+
+    /// Returns the standard TLV type if the TLV field is not a custom field
+    pub fn tlv_type(&self) -> Option<TlvType> {
+        if let TlvTypeField::Standard(tlv_type) = self.tlv_type_field {
+            Some(tlv_type)
+        } else {
+            None
+        }
+    }
+
+    pub fn tlv_type_field(&self) -> TlvTypeField {
+        self.tlv_type_field
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        generic_len_check_data_serialization(buf, self.value().len(), MIN_TLV_LEN)?;
+        buf[0] = self.tlv_type_field.into();
+        self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
+        Ok(self.len_full())
+    }
+
+    pub fn value(&self) -> &[u8] {
+        self.lv.value()
+    }
+
+    /// 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.lv.len_value()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    pub fn len_full(&self) -> usize {
+        self.lv.len_full() + 1
+    }
+
+    /// Checks whether the value field is empty.
+    pub fn is_empty(&self) -> bool {
+        self.lv.is_empty()
+    }
+
+    /// 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> {
+        generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
+        let mut tlv = Self {
+            tlv_type_field: TlvTypeField::from(buf[0]),
+            lv: Lv::from_bytes(&buf[MIN_LV_LEN..])?,
+        };
+        // We re-use this field so we do not need an additional struct field to store the raw start
+        // of the TLV.
+        tlv.lv.raw_data = Some(buf);
+        Ok(tlv)
+    }
+
+    /// If the TLV was generated from a raw bytestream using [Self::from_bytes], the raw start
+    /// of the TLV can be retrieved with this method.
+    pub fn raw_data(&self) -> Option<&[u8]> {
+        self.lv.raw_data()
+    }
+}
+
+pub(crate) fn verify_tlv_type(raw_type: u8, expected_tlv_type: TlvType) -> Result<(), TlvLvError> {
+    let tlv_type = TlvType::try_from(raw_type)
+        .map_err(|_| TlvLvError::InvalidTlvTypeField((raw_type, Some(expected_tlv_type as u8))))?;
+    if tlv_type != expected_tlv_type {
+        return Err(TlvLvError::InvalidTlvTypeField((
+            tlv_type as u8,
+            Some(expected_tlv_type as u8),
+        )));
+    }
+    Ok(())
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct EntityIdTlv {
+    entity_id: UnsignedByteField,
+}
+
+impl EntityIdTlv {
+    pub fn new(entity_id: UnsignedByteField) -> Self {
+        Self { entity_id }
+    }
+
+    fn len_check(buf: &[u8]) -> Result<(), ByteConversionError> {
+        if buf.len() < 2 {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: 2,
+            });
+        }
+        Ok(())
+    }
+
+    pub fn len_value(&self) -> usize {
+        self.entity_id.size()
+    }
+
+    pub fn len_full(&self) -> usize {
+        2 + self.entity_id.size()
+    }
+
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        Self::len_check(buf)?;
+        buf[0] = TlvType::EntityId as u8;
+        buf[1] = self.entity_id.size() as u8;
+        self.entity_id.write_to_be_bytes(&mut buf[2..])
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<Self, TlvLvError> {
+        Self::len_check(buf)?;
+        verify_tlv_type(buf[0], TlvType::EntityId)?;
+        let len = buf[1];
+        if len != 1 && len != 2 && len != 4 && len != 8 {
+            return Err(TlvLvError::InvalidValueLength(len as usize));
+        }
+        // Okay to unwrap here. The checks before make sure that the deserialization never fails
+        let entity_id = UnsignedByteField::new_from_be_bytes(len as usize, &buf[2..]).unwrap();
+        Ok(Self { entity_id })
+    }
+
+    /// Convert to a generic [Tlv], which also erases the programmatic type information.
+    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 {
+            TlvLvError::ByteConversionError(e) => e,
+            // All other errors are impossible.
+            _ => panic!("unexpected TLV error"),
+        })
+    }
+}
+
+impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
+    type Error = TlvLvError;
+
+    fn try_from(value: Tlv) -> Result<Self, Self::Error> {
+        match value.tlv_type_field {
+            TlvTypeField::Standard(tlv_type) => {
+                if tlv_type != TlvType::EntityId {
+                    return Err(TlvLvError::InvalidTlvTypeField((
+                        tlv_type as u8,
+                        Some(TlvType::EntityId as u8),
+                    )));
+                }
+            }
+            TlvTypeField::Custom(val) => {
+                return Err(TlvLvError::InvalidTlvTypeField((
+                    val,
+                    Some(TlvType::EntityId as u8),
+                )));
+            }
+        }
+        let len_value = value.value().len();
+        if len_value != 1 && len_value != 2 && len_value != 4 && len_value != 8 {
+            return Err(TlvLvError::InvalidValueLength(len_value));
+        }
+        Ok(Self::new(
+            UnsignedByteField::new_from_be_bytes(len_value, value.value()).map_err(
+                |e| match e {
+                    UnsignedByteFieldError::ByteConversionError(e) => e,
+                    // This can not happen, we checked for the length validity, and the data is always smaller than
+                    // 255 bytes.
+                    _ => panic!("unexpected error"),
+                },
+            )?,
+        ))
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FilestoreRequestTlv<'first_name, 'second_name> {
+    action_code: FilestoreActionCode,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    first_name: Lv<'first_name>,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    second_name: Option<Lv<'second_name>>,
+}
+
+impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
+    pub fn new_create_file(first_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::CreateFile, first_name, None)
+    }
+
+    pub fn new_delete_file(first_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::DeleteFile, first_name, None)
+    }
+
+    pub fn new_rename_file(
+        source_name: Lv<'first_name>,
+        target_name: Lv<'second_name>,
+    ) -> Result<Self, TlvLvError> {
+        Self::new(
+            FilestoreActionCode::RenameFile,
+            source_name,
+            Some(target_name),
+        )
+    }
+
+    /// This operation appends one file to another. The first specified name will form the first
+    /// part of the new file and the name of the new file. This function can be used to get
+    /// similar functionality to the UNIX cat utility (albeit for only two files).
+    pub fn new_append_file(
+        first_file: Lv<'first_name>,
+        second_file: Lv<'second_name>,
+    ) -> Result<Self, TlvLvError> {
+        Self::new(
+            FilestoreActionCode::AppendFile,
+            first_file,
+            Some(second_file),
+        )
+    }
+
+    /// This operation replaces the content of the first specified file with the content of
+    /// the secondly specified file. This function can be used to get similar functionality to
+    /// the UNIX copy (cp) utility if the target file already exists.
+    pub fn new_replace_file(
+        replaced_file: Lv<'first_name>,
+        new_file: Lv<'second_name>,
+    ) -> Result<Self, TlvLvError> {
+        Self::new(
+            FilestoreActionCode::ReplaceFile,
+            replaced_file,
+            Some(new_file),
+        )
+    }
+
+    pub fn new_create_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::CreateDirectory, dir_name, None)
+    }
+
+    pub fn new_remove_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::RemoveDirectory, dir_name, None)
+    }
+
+    pub fn new_deny_file(file_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::DenyFile, file_name, None)
+    }
+
+    pub fn new_deny_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::DenyDirectory, dir_name, None)
+    }
+
+    /// This function will return [None] if the respective action code requires two names but
+    /// only one is passed. It will also returns [None] if the cumulative length of the first
+    /// name and the second name exceeds 255 bytes.
+    ///
+    /// This is the case for the rename, append and replace filestore request.
+    pub fn new(
+        action_code: FilestoreActionCode,
+        first_name: Lv<'first_name>,
+        second_name: Option<Lv<'second_name>>,
+    ) -> Result<Self, TlvLvError> {
+        let mut base_value_len = first_name.len_full();
+        if Self::has_second_filename(action_code) {
+            if second_name.is_none() {
+                return Err(TlvLvError::SecondNameMissing);
+            }
+            base_value_len += second_name.as_ref().unwrap().len_full();
+        }
+        if base_value_len > u8::MAX as usize {
+            return Err(TlvLvError::InvalidValueLength(base_value_len));
+        }
+        Ok(Self {
+            action_code,
+            first_name,
+            second_name,
+        })
+    }
+
+    pub fn has_second_filename(action_code: FilestoreActionCode) -> bool {
+        if action_code == FilestoreActionCode::RenameFile
+            || action_code == FilestoreActionCode::AppendFile
+            || action_code == FilestoreActionCode::ReplaceFile
+        {
+            return true;
+        }
+        false
+    }
+
+    pub fn action_code(&self) -> FilestoreActionCode {
+        self.action_code
+    }
+
+    pub fn first_name(&self) -> Lv<'first_name> {
+        self.first_name
+    }
+
+    pub fn second_name(&self) -> Option<Lv<'second_name>> {
+        self.second_name
+    }
+
+    pub fn len_value(&self) -> usize {
+        let mut len = 1 + self.first_name.len_full();
+        if let Some(second_name) = self.second_name {
+            len += second_name.len_full();
+        }
+        len
+    }
+
+    pub fn len_full(&self) -> usize {
+        2 + self.len_value()
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.len_full() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_full(),
+            });
+        }
+        buf[0] = TlvType::FilestoreRequest as u8;
+        buf[1] = self.len_value() as u8;
+        buf[2] = (self.action_code as u8) << 4;
+        let mut current_idx = 3;
+        // Length checks were already performed.
+        self.first_name.write_to_be_bytes_no_len_check(
+            &mut buf[current_idx..current_idx + self.first_name.len_full()],
+        );
+        current_idx += self.first_name.len_full();
+        if let Some(second_name) = self.second_name {
+            second_name.write_to_be_bytes_no_len_check(
+                &mut buf[current_idx..current_idx + second_name.len_full()],
+            );
+            current_idx += second_name.len_full();
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes<'longest: 'first_name + 'second_name>(
+        buf: &'longest [u8],
+    ) -> Result<Self, TlvLvError> {
+        if buf.len() < 2 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 2,
+            }
+            .into());
+        }
+        verify_tlv_type(buf[0], TlvType::FilestoreRequest)?;
+        let len = buf[1] as usize;
+        let mut current_idx = 2;
+        let action_code = FilestoreActionCode::try_from((buf[2] >> 4) & 0b1111)
+            .map_err(|_| TlvLvError::InvalidFilestoreActionCode((buf[2] >> 4) & 0b1111))?;
+        current_idx += 1;
+        let first_name = Lv::from_bytes(&buf[current_idx..])?;
+        let mut second_name = None;
+
+        current_idx += first_name.len_full();
+        if Self::has_second_filename(action_code) {
+            if current_idx >= 2 + len {
+                return Err(TlvLvError::SecondNameMissing);
+            }
+            second_name = Some(Lv::from_bytes(&buf[current_idx..])?);
+        }
+        Ok(Self {
+            action_code,
+            first_name,
+            second_name,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::tlv::{FilestoreActionCode, FilestoreRequestTlv, Tlv, TlvType, TlvTypeField};
+    use crate::cfdp::TlvLvError;
+    use crate::util::{UbfU8, UnsignedEnum};
+
+    const TLV_TEST_STR_0: &str = "hello.txt";
+    const TLV_TEST_STR_1: &str = "hello2.txt";
+
+    #[test]
+    fn test_basic() {
+        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();
+        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_serialization() {
+        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 mut ser_buf: [u8; 4] = [0; 4];
+        assert!(tlv_res.write_to_bytes(&mut ser_buf).is_ok());
+        assert_eq!(ser_buf[0], TlvType::EntityId as u8);
+        assert_eq!(ser_buf[1], 1);
+        assert_eq!(ser_buf[2], 5);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf[2..]).is_ok());
+        buf[0] = TlvType::EntityId as u8;
+        buf[1] = 1;
+        let tlv_from_raw = Tlv::from_bytes(&buf);
+        assert!(tlv_from_raw.is_ok());
+        let tlv_from_raw = tlv_from_raw.unwrap();
+        assert!(tlv_from_raw.raw_data().is_some());
+        assert_eq!(tlv_from_raw.raw_data().unwrap(), buf);
+        assert_eq!(
+            tlv_from_raw.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::EntityId)
+        );
+        assert_eq!(tlv_from_raw.value().len(), 1);
+        assert_eq!(tlv_from_raw.len_full(), 3);
+        assert_eq!(tlv_from_raw.value()[0], 5);
+    }
+
+    #[test]
+    fn test_empty() {
+        let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
+        assert_eq!(tlv_empty.value().len(), 0);
+        assert!(tlv_empty.is_empty());
+        assert_eq!(tlv_empty.len_full(), 2);
+        assert!(tlv_empty.value().is_empty());
+        assert_eq!(
+            tlv_empty.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+    }
+
+    #[test]
+    fn test_empty_serialization() {
+        let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(tlv_empty.write_to_bytes(&mut buf).is_ok());
+        assert_eq!(buf[0], TlvType::MsgToUser as u8);
+        assert_eq!(buf[1], 0);
+    }
+
+    #[test]
+    fn test_empty_deserialization() {
+        let mut buf: [u8; 4] = [0; 4];
+        buf[0] = TlvType::MsgToUser as u8;
+        buf[1] = 0;
+        let tlv_empty = Tlv::from_bytes(&buf);
+        assert!(tlv_empty.is_ok());
+        let tlv_empty = tlv_empty.unwrap();
+        assert!(tlv_empty.is_empty());
+        assert_eq!(tlv_empty.value().len(), 0);
+        assert_eq!(
+            tlv_empty.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+        assert_eq!(tlv_empty.len_full(), 2);
+        assert!(tlv_empty.value().is_empty());
+    }
+
+    #[test]
+    fn test_buf_too_large() {
+        let buf_too_large: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
+        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 {
+            assert_eq!(size, u8::MAX as usize + 1);
+        } else {
+            panic!("unexpected error {:?}", error);
+        }
+    }
+
+    #[test]
+    fn test_deserialization_custom_tlv_type() {
+        let mut buf: [u8; 4] = [0; 4];
+        buf[0] = 3;
+        buf[1] = 1;
+        buf[2] = 5;
+        let tlv = Tlv::from_bytes(&buf);
+        assert!(tlv.is_ok());
+        let tlv = tlv.unwrap();
+        assert_eq!(tlv.tlv_type_field(), TlvTypeField::Custom(3));
+        assert_eq!(tlv.value().len(), 1);
+        assert_eq!(tlv.len_full(), 3);
+    }
+
+    fn generic_fs_request_test_one_file(
+        action_code: FilestoreActionCode,
+    ) -> FilestoreRequestTlv<'static, 'static> {
+        assert!(!FilestoreRequestTlv::has_second_filename(action_code));
+        let first_name = Lv::new_from_str(TLV_TEST_STR_0).unwrap();
+        let fs_request = match action_code {
+            FilestoreActionCode::CreateFile => FilestoreRequestTlv::new_create_file(first_name),
+            FilestoreActionCode::DeleteFile => FilestoreRequestTlv::new_delete_file(first_name),
+            FilestoreActionCode::CreateDirectory => {
+                FilestoreRequestTlv::new_create_directory(first_name)
+            }
+            FilestoreActionCode::RemoveDirectory => {
+                FilestoreRequestTlv::new_remove_directory(first_name)
+            }
+            FilestoreActionCode::DenyFile => FilestoreRequestTlv::new_deny_file(first_name),
+            FilestoreActionCode::DenyDirectory => {
+                FilestoreRequestTlv::new_deny_directory(first_name)
+            }
+            _ => panic!("invalid action code"),
+        };
+        assert!(fs_request.is_ok());
+        let fs_request = fs_request.unwrap();
+        assert_eq!(fs_request.len_value(), 1 + first_name.len_full());
+        assert_eq!(fs_request.len_full(), fs_request.len_value() + 2);
+        assert_eq!(fs_request.action_code(), action_code);
+        assert_eq!(fs_request.first_name(), first_name);
+        assert_eq!(fs_request.second_name(), None);
+        fs_request
+    }
+
+    fn generic_fs_request_test_two_files(
+        action_code: FilestoreActionCode,
+    ) -> FilestoreRequestTlv<'static, 'static> {
+        assert!(FilestoreRequestTlv::has_second_filename(action_code));
+        let first_name = Lv::new_from_str(TLV_TEST_STR_0).unwrap();
+        let second_name = Lv::new_from_str(TLV_TEST_STR_1).unwrap();
+        let fs_request = match action_code {
+            FilestoreActionCode::ReplaceFile => {
+                FilestoreRequestTlv::new_replace_file(first_name, second_name)
+            }
+            FilestoreActionCode::AppendFile => {
+                FilestoreRequestTlv::new_append_file(first_name, second_name)
+            }
+            FilestoreActionCode::RenameFile => {
+                FilestoreRequestTlv::new_rename_file(first_name, second_name)
+            }
+            _ => panic!("invalid action code"),
+        };
+        assert!(fs_request.is_ok());
+        let fs_request = fs_request.unwrap();
+        assert_eq!(
+            fs_request.len_value(),
+            1 + first_name.len_full() + second_name.len_full()
+        );
+        assert_eq!(fs_request.len_full(), fs_request.len_value() + 2);
+        assert_eq!(fs_request.action_code(), action_code);
+        assert_eq!(fs_request.first_name(), first_name);
+        assert!(fs_request.second_name().is_some());
+        assert_eq!(fs_request.second_name().unwrap(), second_name);
+        fs_request
+    }
+
+    #[test]
+    fn test_fs_request_basic_create_file() {
+        generic_fs_request_test_one_file(FilestoreActionCode::CreateFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_delete() {
+        generic_fs_request_test_one_file(FilestoreActionCode::DeleteFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_create_dir() {
+        generic_fs_request_test_one_file(FilestoreActionCode::CreateDirectory);
+    }
+
+    #[test]
+    fn test_fs_request_basic_remove_dir() {
+        generic_fs_request_test_one_file(FilestoreActionCode::RemoveDirectory);
+    }
+
+    #[test]
+    fn test_fs_request_basic_deny_file() {
+        generic_fs_request_test_one_file(FilestoreActionCode::DenyFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_deny_dir() {
+        generic_fs_request_test_one_file(FilestoreActionCode::DenyDirectory);
+    }
+
+    #[test]
+    fn test_fs_request_basic_append_file() {
+        generic_fs_request_test_two_files(FilestoreActionCode::AppendFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_rename_file() {
+        generic_fs_request_test_two_files(FilestoreActionCode::RenameFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_replace_file() {
+        generic_fs_request_test_two_files(FilestoreActionCode::ReplaceFile);
+    }
+
+    fn check_fs_request_first_part(
+        buf: &[u8],
+        action_code: FilestoreActionCode,
+        expected_val_len: u8,
+    ) -> usize {
+        assert_eq!(buf[0], TlvType::FilestoreRequest as u8);
+        assert_eq!(buf[1], expected_val_len);
+        assert_eq!((buf[2] >> 4) & 0b1111, action_code as u8);
+        let lv = Lv::from_bytes(&buf[3..]);
+        assert!(lv.is_ok());
+        let lv = lv.unwrap();
+        assert_eq!(lv.value_as_str().unwrap().unwrap(), TLV_TEST_STR_0);
+        3 + lv.len_full()
+    }
+
+    #[test]
+    fn test_fs_request_serialization_one_file() {
+        let req = generic_fs_request_test_one_file(FilestoreActionCode::CreateFile);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = req.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 3 + 1 + TLV_TEST_STR_0.len());
+        assert_eq!(written, req.len_full());
+        check_fs_request_first_part(
+            &buf,
+            FilestoreActionCode::CreateFile,
+            1 + 1 + TLV_TEST_STR_0.len() as u8,
+        );
+    }
+
+    #[test]
+    fn test_fs_request_deserialization_one_file() {
+        let req = generic_fs_request_test_one_file(FilestoreActionCode::CreateFile);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = req.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let req_conv_back = FilestoreRequestTlv::from_bytes(&buf);
+        assert!(req_conv_back.is_ok());
+        let req_conv_back = req_conv_back.unwrap();
+        assert_eq!(req_conv_back, req);
+    }
+
+    #[test]
+    fn test_fs_request_serialization_two_files() {
+        let req = generic_fs_request_test_two_files(FilestoreActionCode::RenameFile);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = req.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, req.len_full());
+        assert_eq!(
+            written,
+            3 + 1 + TLV_TEST_STR_0.len() + 1 + TLV_TEST_STR_1.len()
+        );
+        let current_idx = check_fs_request_first_part(
+            &buf,
+            FilestoreActionCode::RenameFile,
+            1 + 1 + TLV_TEST_STR_0.len() as u8 + 1 + TLV_TEST_STR_1.len() as u8,
+        );
+        let second_lv = Lv::from_bytes(&buf[current_idx..]);
+        assert!(second_lv.is_ok());
+        let second_lv = second_lv.unwrap();
+        assert_eq!(second_lv.value_as_str().unwrap().unwrap(), TLV_TEST_STR_1);
+        assert_eq!(current_idx + second_lv.len_full(), req.len_full());
+    }
+
+    #[test]
+    fn test_fs_request_deserialization_two_files() {
+        let req = generic_fs_request_test_two_files(FilestoreActionCode::RenameFile);
+        let mut buf: [u8; 64] = [0; 64];
+        req.write_to_bytes(&mut buf).unwrap();
+        let req_conv_back = FilestoreRequestTlv::from_bytes(&buf);
+        assert!(req_conv_back.is_ok());
+        let req_conv_back = req_conv_back.unwrap();
+        assert_eq!(req_conv_back, req);
+    }
+}

src/cfdp/tlv/msg_to_user.rs

@@ -0,0 +1,110 @@
+//! Abstractions for the Message to User CFDP TLV subtype.
+use super::{Tlv, TlvLvError, TlvType, TlvTypeField};
+use crate::ByteConversionError;
+use delegate::delegate;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct MsgToUserTlv<'data> {
+    pub tlv: Tlv<'data>,
+}
+
+impl<'data> MsgToUserTlv<'data> {
+    /// Create a new message to user TLV where the type field is set correctly.
+    pub fn new(value: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvError> {
+        Ok(Self {
+            tlv: Tlv::new(TlvType::MsgToUser, value)?,
+        })
+    }
+
+    delegate! {
+        to self.tlv {
+            pub fn tlv_type_field(&self) -> TlvTypeField;
+            pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+            pub fn value(&self) -> &[u8];
+            /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
+            /// [Self::value]
+            pub fn len_value(&self) -> usize;
+            /// Returns the full raw length, including the length byte.
+            pub fn len_full(&self) -> usize;
+            /// Checks whether the value field is empty.
+            pub fn is_empty(&self) -> bool;
+            /// If the TLV was generated from a raw bytestream using [Self::from_bytes], the raw start
+            /// of the TLV can be retrieved with this method.
+            pub fn raw_data(&self) -> Option<&[u8]>;
+        }
+    }
+
+    pub fn is_standard_tlv(&self) -> bool {
+        true
+    }
+
+    pub fn tlv_type(&self) -> Option<TlvType> {
+        Some(TlvType::MsgToUser)
+    }
+
+    /// Check whether this message is a reserved CFDP message like a Proxy Operation Message.
+    pub fn is_reserved_cfdp_msg(&self) -> bool {
+        if self.value().len() < 4 {
+            return false;
+        }
+        let value = self.value();
+        if value[0] == b'c' && value[1] == b'f' && value[2] == b'd' && value[3] == b'p' {
+            return true;
+        }
+        false
+    }
+
+    /// This is a thin wrapper around [Tlv::from_bytes] with the additional type check.
+    pub fn from_bytes(buf: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvError> {
+        let msg_to_user = Self {
+            tlv: Tlv::from_bytes(buf)?,
+        };
+        match msg_to_user.tlv_type_field() {
+            TlvTypeField::Standard(tlv_type) => {
+                if tlv_type != TlvType::MsgToUser {
+                    return Err(TlvLvError::InvalidTlvTypeField((
+                        tlv_type as u8,
+                        Some(TlvType::MsgToUser as u8),
+                    )));
+                }
+            }
+            TlvTypeField::Custom(raw) => {
+                return Err(TlvLvError::InvalidTlvTypeField((
+                    raw,
+                    Some(TlvType::MsgToUser as u8),
+                )));
+            }
+        }
+        Ok(msg_to_user)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    #[test]
+    fn test_basic() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value);
+        assert!(msg_to_user.is_ok());
+        let msg_to_user = msg_to_user.unwrap();
+        assert!(msg_to_user.is_standard_tlv());
+        assert_eq!(msg_to_user.tlv_type().unwrap(), TlvType::MsgToUser);
+        assert_eq!(msg_to_user.value(), custom_value);
+        assert_eq!(msg_to_user.value().len(), 4);
+        assert_eq!(msg_to_user.len_value(), 4);
+        assert_eq!(msg_to_user.len_full(), 6);
+        assert!(!msg_to_user.is_empty());
+        assert!(msg_to_user.raw_data().is_none());
+        assert!(!msg_to_user.is_reserved_cfdp_msg());
+    }
+
+    #[test]
+    fn test_reserved_msg() {
+        let reserved_str = "cfdp";
+        let msg_to_user = MsgToUserTlv::new(reserved_str.as_bytes());
+        assert!(msg_to_user.is_ok());
+        let msg_to_user = msg_to_user.unwrap();
+        assert!(msg_to_user.is_reserved_cfdp_msg());
+    }
+}

src/ecss/event.rs

@@ -0,0 +1,43 @@
+//! PUS Service 5 Events
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum Subservice {
+    TmInfoReport = 1,
+    TmLowSeverityReport = 2,
+    TmMediumSeverityReport = 3,
+    TmHighSeverityReport = 4,
+    TcEnableEventGeneration = 5,
+    TcDisableEventGeneration = 6,
+    TcReportDisabledList = 7,
+    TmDisabledEventsReport = 8,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_conv_into_u8() {
+        let subservice: u8 = Subservice::TmLowSeverityReport.into();
+        assert_eq!(subservice, 2);
+    }
+
+    #[test]
+    fn test_conv_from_u8() {
+        let subservice: Subservice = 2.try_into().unwrap();
+        assert_eq!(subservice, Subservice::TmLowSeverityReport);
+    }
+
+    #[test]
+    fn test_conv_fails() {
+        let conversion = Subservice::try_from(9);
+        assert!(conversion.is_err());
+        let err = conversion.unwrap_err();
+        assert_eq!(err.number, 9);
+    }
+}

src/ecss/hk.rs

@@ -0,0 +1,31 @@
+//! PUS Service 3 Housekeeping
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum Subservice {
+    // Regular HK
+    TcCreateHkReportStructure = 1,
+    TcDeleteHkReportStructures = 3,
+    TcEnableHkGeneration = 5,
+    TcDisableHkGeneration = 6,
+    TcReportHkReportStructures = 9,
+    TmHkPacket = 25,
+    TcGenerateOneShotHk = 27,
+    TcModifyHkCollectionInterval = 31,
+
+    // Diagnostics HK
+    TcCreateDiagReportStructure = 2,
+    TcDeleteDiagReportStructures = 4,
+    TcEnableDiagGeneration = 7,
+    TcDisableDiagGeneration = 8,
+    TmHkStructuresReport = 10,
+    TcReportDiagReportStructures = 11,
+    TmDiagStructuresReport = 12,
+    TmDiagPacket = 26,
+    TcGenerateOneShotDiag = 28,
+    TcModifyDiagCollectionInterval = 32,
+}

src/ecss/mod.rs

@@ -1,19 +1,77 @@
 //! 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/)
-use crate::{ByteConversionError, CcsdsPacket, SizeMissmatch};
-use core::fmt::Debug;
+//!
+//! You can find the PUS telecommand definitions in the [tc] module and ithe PUS telemetry definitions
+//! inside the [tm] module.
+use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
+use core::fmt::{Debug, Display, Formatter};
 use core::mem::size_of;
-use crc::{Crc, CRC_16_IBM_3740};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub mod event;
+pub mod hk;
+pub mod scheduling;
+pub mod tc;
+pub mod tm;
+pub mod verification;
 
 pub type CrcType = u16;
-
-/// CRC algorithm used by the PUS standard.
-pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
 pub const CCSDS_HEADER_LEN: usize = size_of::<crate::zc::SpHeader>();
 
+#[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+#[non_exhaustive]
+pub enum PusServiceId {
+    /// Service 1
+    Verification = 1,
+    /// Service 2
+    DeviceAccess = 2,
+    /// Service 3
+    Housekeeping = 3,
+    /// Service 4
+    ParameterStatistics = 4,
+    /// Service 5
+    Event = 5,
+    /// Service 6
+    MemoryManagement = 6,
+    /// Service 8
+    Action = 8,
+    /// Service 9
+    TimeManagement = 9,
+    /// Service 11
+    Scheduling = 11,
+    /// Service 12
+    OnBoardMonitoring = 12,
+    /// Service 13
+    LargePacketTransfer = 13,
+    /// Service 14
+    RealTimeForwardingControl = 14,
+    /// Service 15
+    StorageAndRetrival = 15,
+    /// Service 17
+    Test = 17,
+    /// Service 18
+    OpsAndProcedures = 18,
+    /// Service 19
+    EventAction = 19,
+    /// Service 20
+    Parameter = 20,
+    /// Service 21
+    RequestSequencing = 21,
+    /// Service 22
+    PositionBasedScheduling = 22,
+    /// Service 23
+    FileManagement = 23,
+}
+
 /// All PUS versions. Only PUS C is supported by this library.
-#[derive(PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Debug)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PusVersion {
     EsaPus = 0,
     PusA = 1,
@@ -34,7 +92,9 @@ impl TryFrom<u8> for PusVersion {
     }
 }
 
+/// ECSS Packet Type Codes (PTC)s.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PacketTypeCodes {
     Boolean = 1,
     Enumerated = 2,
@@ -50,7 +110,40 @@ pub enum PacketTypeCodes {
     Packet = 12,
 }
 
+pub type Ptc = PacketTypeCodes;
+
+/// ECSS Packet Field Codes (PFC)s for the unsigned [Ptc].
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum UnsignedPfc {
+    OneByte = 4,
+    TwelveBits = 8,
+    TwoBytes = 12,
+    ThreeBytes = 13,
+    FourBytes = 14,
+    SixBytes = 15,
+    EightBytes = 16,
+    OneBit = 17,
+    TwoBits = 18,
+    ThreeBits = 19,
+}
+
+/// ECSS Packet Field Codes (PFC)s for the real (floating point) [Ptc].
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum RealPfc {
+    /// 4 octets simple precision format (IEEE)
+    Float = 1,
+    /// 8 octets simple precision format (IEEE)
+    Double = 2,
+    /// 4 octets simple precision format (MIL-STD)
+    FloatMilStd = 3,
+    /// 8 octets simple precision format (MIL-STD)
+    DoubleMilStd = 4,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PusError {
     VersionNotSupported(PusVersion),
     IncorrectCrc(u16),
@@ -58,23 +151,62 @@ pub enum PusError {
     NoRawData,
     /// CRC16 needs to be calculated first
     CrcCalculationMissing,
-    ByteConversionError(ByteConversionError),
+    ByteConversion(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::IncorrectCrc(crc) => {
+                write!(f, "crc16 {crc:#04x} is incorrect")
+            }
+            PusError::RawDataTooShort(size) => {
+                write!(
+                    f,
+                    "deserialization error, provided raw data with size {size} too short"
+                )
+            }
+            PusError::NoRawData => {
+                write!(f, "no raw data provided")
+            }
+            PusError::CrcCalculationMissing => {
+                write!(f, "crc16 was not calculated")
+            }
+            PusError::ByteConversion(e) => {
+                write!(f, "low level byte conversion 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::ByteConversionError(e)
+        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) -> PusVersion;
     fn service(&self) -> u8;
     fn subservice(&self) -> u8;
-
-    fn user_data(&self) -> Option<&[u8]>;
+    fn user_data(&self) -> &[u8];
     fn crc16(&self) -> Option<u16>;
 }
 
@@ -118,21 +250,29 @@ pub(crate) fn user_data_from_raw(
     total_len: usize,
     raw_data_len: usize,
     slice: &[u8],
-) -> Result<Option<&[u8]>, PusError> {
+) -> Result<&[u8], PusError> {
     match current_idx {
-        _ if current_idx == total_len - 2 => Ok(None),
         _ if current_idx > total_len - 2 => Err(PusError::RawDataTooShort(raw_data_len)),
-        _ => Ok(Some(&slice[current_idx..total_len - 2])),
+        _ => Ok(&slice[current_idx..total_len - 2]),
     }
 }
 
-pub(crate) fn verify_crc16_from_raw(raw_data: &[u8], crc16: u16) -> Result<(), PusError> {
+pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
+    raw_data: &[u8],
+    crc16: u16,
+) -> Result<(), PusError> {
+    verify_crc16_ccitt_false_from_raw(raw_data)
+        .then(|| ())
+        .ok_or(PusError::IncorrectCrc(crc16))
+}
+
+pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
     let mut digest = CRC_CCITT_FALSE.digest();
     digest.update(raw_data);
     if digest.finalize() == 0 {
-        return Ok(());
+        return true;
     }
-    Err(PusError::IncorrectCrc(crc16))
+    false
 }
 
 macro_rules! ccsds_impl {
@@ -156,6 +296,7 @@ macro_rules! sp_header_impls {
     }
 }
 
+use crate::util::{GenericUnsignedByteField, ToBeBytes, UnsignedEnum};
 pub(crate) use ccsds_impl;
 pub(crate) use sp_header_impls;
 
@@ -163,57 +304,17 @@ pub(crate) use sp_header_impls;
 /// and an unsigned value. The trait makes no assumptions about the actual type of the unsigned
 /// value and only requires implementors to implement a function which writes the enumeration into
 /// a raw byte format.
-pub trait EcssEnumeration {
+pub trait EcssEnumeration: UnsignedEnum {
     /// Packet Format Code, which denotes the number of bits of the enumeration
     fn pfc(&self) -> u8;
-    fn byte_width(&self) -> usize {
-        (self.pfc() / 8) as usize
-    }
-    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError>;
 }
 
 pub trait EcssEnumerationExt: EcssEnumeration + Debug + Copy + Clone + PartialEq + Eq {}
 
-pub trait ToBeBytes {
-    type ByteArray: AsRef<[u8]>;
-    fn to_be_bytes(&self) -> Self::ByteArray;
-}
-
-impl ToBeBytes for u8 {
-    type ByteArray = [u8; 1];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u8::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u16 {
-    type ByteArray = [u8; 2];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u16::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u32 {
-    type ByteArray = [u8; 4];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u32::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u64 {
-    type ByteArray = [u8; 8];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u64::to_be_bytes(*self)
-    }
-}
-
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct GenericEcssEnumWrapper<TYPE> {
-    val: TYPE,
+    field: GenericUnsignedByteField<TYPE>,
 }
 
 impl<TYPE> GenericEcssEnumWrapper<TYPE> {
@@ -222,7 +323,19 @@ impl<TYPE> GenericEcssEnumWrapper<TYPE> {
     }
 
     pub fn new(val: TYPE) -> Self {
-        Self { val }
+        Self {
+            field: GenericUnsignedByteField::new(val),
+        }
+    }
+}
+
+impl<TYPE: ToBeBytes> UnsignedEnum for GenericEcssEnumWrapper<TYPE> {
+    fn size(&self) -> usize {
+        (self.pfc() / 8) as usize
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.field.write_to_be_bytes(buf)
     }
 }
 
@@ -230,17 +343,6 @@ impl<TYPE: ToBeBytes> EcssEnumeration for GenericEcssEnumWrapper<TYPE> {
     fn pfc(&self) -> u8 {
         size_of::<TYPE>() as u8 * 8_u8
     }
-
-    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError> {
-        if buf.len() < self.byte_width() as usize {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: buf.len(),
-                expected: self.byte_width() as usize,
-            }));
-        }
-        buf[0..self.byte_width() as usize].copy_from_slice(self.val.to_be_bytes().as_ref());
-        Ok(())
-    }
 }
 
 impl<TYPE: Debug + Copy + Clone + PartialEq + Eq + ToBeBytes> EcssEnumerationExt
@@ -253,9 +355,17 @@ pub type EcssEnumU16 = GenericEcssEnumWrapper<u16>;
 pub type EcssEnumU32 = GenericEcssEnumWrapper<u32>;
 pub type EcssEnumU64 = GenericEcssEnumWrapper<u64>;
 
+/// Generic trait for PUS packet abstractions which can written to a raw slice as their raw
+/// byte representation. This is especially useful for generic abstractions which depend only
+/// on the serialization of those packets.
+pub trait SerializablePusPacket {
+    fn len_packed(&self) -> usize;
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+}
+
 #[cfg(test)]
 mod tests {
-    use crate::ecss::{EcssEnumU16, EcssEnumU32, EcssEnumU8, EcssEnumeration};
+    use crate::ecss::{EcssEnumU16, EcssEnumU32, EcssEnumU8, UnsignedEnum};
     use crate::ByteConversionError;
 
     #[test]
@@ -287,9 +397,9 @@ mod tests {
         assert!(res.is_err());
         let error = res.unwrap_err();
         match error {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.expected, 2);
-                assert_eq!(missmatch.found, 1);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(expected, 2);
+                assert_eq!(found, 1);
             }
             _ => {
                 panic!("Unexpected error {:?}", error);
@@ -318,9 +428,9 @@ mod tests {
         assert!(res.is_err());
         let error = res.unwrap_err();
         match error {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.expected, 4);
-                assert_eq!(missmatch.found, 3);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(expected, 4);
+                assert_eq!(found, 3);
             }
             _ => {
                 panic!("Unexpected error {:?}", error);

src/ecss/scheduling.rs

@@ -0,0 +1,105 @@
+//! PUS Service 11 Scheduling
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum Subservice {
+    // Core subservices
+    TcEnableScheduling = 1,
+    TcDisableScheduling = 2,
+    TcResetScheduling = 3,
+    TcInsertActivity = 4,
+    TcDeleteActivityByRequestId = 5,
+    TcDeleteActivitiesByFilter = 6,
+
+    // Time shift subservices
+    TcTimeShiftActivityWithRequestId = 7,
+    TcTimeShiftActivitiesByFilter = 8,
+    TcTimeShiftAll = 15,
+
+    // Reporting subservices
+    TcDetailReportByRequestId = 9,
+    TmDetailReport = 10,
+    TcDetailReportByFilter = 11,
+    TcSummaryReportByRequestId = 12,
+    TmSummaryReport = 13,
+    TcSummaryReportByFilter = 14,
+    TcDetailReportAll = 16,
+    TcSummaryReportAll = 17,
+
+    // Subschedule subservices
+    TcReportSubscheduleStatus = 18,
+    TmReportSubscheduleStatus = 19,
+    TcEnableSubschedule = 20,
+    TcDisableSubschedule = 21,
+
+    // Group subservices
+    TcCreateScheduleGroup = 22,
+    TcDeleteScheduleGroup = 23,
+    TcEnableScheduleGroup = 24,
+    TcDisableScheduleGroup = 25,
+    TcReportAllGroupsStatus = 26,
+    TmReportAllGroupsStatus = 27,
+}
+
+/// 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 = "serde", derive(Serialize, Deserialize))]
+pub enum SchedStatus {
+    Disabled = 0,
+    Enabled = 1,
+}
+
+impl From<bool> for SchedStatus {
+    fn from(value: bool) -> Self {
+        if value {
+            SchedStatus::Enabled
+        } else {
+            SchedStatus::Disabled
+        }
+    }
+}
+
+/// Time window types as specified in  ECSS-E-ST-70-41C 8.11.3
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum TimeWindowType {
+    SelectAll = 0,
+    TimeTagToTimeTag = 1,
+    FromTimeTag = 2,
+    ToTimeTag = 3,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_bool_conv_0() {
+        let enabled = true;
+        let status: SchedStatus = enabled.into();
+        assert_eq!(status, SchedStatus::Enabled)
+    }
+
+    #[test]
+    fn test_bool_conv_1() {
+        let enabled = false;
+        let status: SchedStatus = enabled.into();
+        assert_eq!(status, SchedStatus::Disabled)
+    }
+
+    #[test]
+    fn test_conv_into_u8() {
+        let subservice: u8 = Subservice::TcCreateScheduleGroup.into();
+        assert_eq!(subservice, 22);
+    }
+
+    #[test]
+    fn test_conv_from_u8() {
+        let subservice: Subservice = 22u8.try_into().unwrap();
+        assert_eq!(subservice, Subservice::TcCreateScheduleGroup);
+    }
+}

src/ecss/verification.rs

@@ -0,0 +1,35 @@
+//! PUS Service 1 Verification
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum Subservice {
+    TmAcceptanceSuccess = 1,
+    TmAcceptanceFailure = 2,
+    TmStartSuccess = 3,
+    TmStartFailure = 4,
+    TmStepSuccess = 5,
+    TmStepFailure = 6,
+    TmCompletionSuccess = 7,
+    TmCompletionFailure = 8,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_conv_into_u8() {
+        let subservice: u8 = Subservice::TmCompletionSuccess.into();
+        assert_eq!(subservice, 7);
+    }
+
+    #[test]
+    fn test_conv_from_u8() {
+        let subservice: Subservice = 7.try_into().unwrap();
+        assert_eq!(subservice, Subservice::TmCompletionSuccess);
+    }
+}

src/lib.rs

@@ -7,77 +7,138 @@
 //!
 //!  - Space Packet implementation according to
 //!    [CCSDS Blue Book 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf)
+//!  - CCSDS File Delivery Protocol (CFDP) packet implementations according to
+//!    [CCSDS Blue Book 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf)
 //!  - PUS Telecommand and PUS Telemetry implementation according to the
 //!    [ECSS-E-ST-70-41C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
-//!  - CDS Short Time Code implementation according to
-//!    [CCSDS CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
+//!  - CUC (CCSDS Unsegmented Time Code) implementation according to
+//!    [CCSDS 301.0-B-4 3.2](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
+//!  - CDS (CCSDS Day Segmented Time Code) implementation according to
+//!    [CCSDS 301.0-B-4 3.3](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
+//!  - Some helper types to support ASCII timecodes as specified in
+//!    [CCSDS 301.0-B-4 3.5](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 //!
 //! ## Features
 //!
 //! `spacepackets` supports various runtime environments and is also suitable for `no_std` environments.
 //!
-//! It also offers support for [`serde`](https://serde.rs/). The Space Packet, PUS TM and TC
-//! implementations derive the `serde` `Serialize` and `Deserialize` trait. This allows serializing and
+//! 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:
+//! ### Default features
 //!
 //!  - [`std`](https://doc.rust-lang.org/std/): Enables functionality relying on the standard library.
 //!  - [`alloc`](https://doc.rust-lang.org/alloc/): Enables features which operate on containers
 //!     like [`alloc::vec::Vec`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html).
 //!     Enabled by the `std` feature.
 //!
+//! ### Optional features
+//!
+//!  - [`serde`](https://serde.rs/): Adds `serde` support for most types by adding `Serialize` and
+//!    `Deserialize` `derive`s
+//!
 //! ## Module
 //!
 //! This module contains helpers and data structures to generate Space Packets according to the
 //! [CCSDS 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf). This includes the
-//! [SpHeader] class to generate the Space Packet Header component common to all space packets
+//! [SpHeader] class to generate the Space Packet Header component common to all space packets.
 //!
 //! ## Example
 //!
 //! ```rust
 //! use spacepackets::SpHeader;
-//! let sp_header = SpHeader::tc(0x42, 12, 0).expect("Error creating SP header");
+//! let sp_header = SpHeader::tc_unseg(0x42, 12, 1).expect("Error creating CCSDS TC header");
 //! println!("{:?}", sp_header);
+//! let mut ccsds_buf: [u8; 32] = [0; 32];
+//! sp_header.write_to_be_bytes(&mut ccsds_buf).expect("Writing CCSDS TC header failed");
+//! println!("{:x?}", &ccsds_buf[0..6]);
 //! ```
 #![no_std]
+#![cfg_attr(doc_cfg, feature(doc_cfg))]
 #[cfg(feature = "alloc")]
 extern crate alloc;
 #[cfg(any(feature = "std", test))]
 extern crate std;
 
 use crate::ecss::CCSDS_HEADER_LEN;
+use core::fmt::{Debug, Display, Formatter};
+use crc::{Crc, CRC_16_IBM_3740};
 use delegate::delegate;
 
+#[cfg(feature = "std")]
+use std::error::Error;
+
+#[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+pub mod cfdp;
 pub mod ecss;
-pub mod tc;
 pub mod time;
-pub mod tm;
+pub mod util;
+
+mod private {
+    pub trait Sealed {}
+}
+
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard.
+pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
 
 pub const MAX_APID: u16 = 2u16.pow(11) - 1;
 pub const MAX_SEQ_COUNT: u16 = 2u16.pow(14) - 1;
 
+/// Generic error type when converting to and from raw byte slices.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub struct SizeMissmatch {
-    pub found: usize,
-    pub expected: usize,
-}
-
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum ByteConversionError {
     /// The passed slice is too small. Returns the passed slice length and expected minimum size
-    ToSliceTooSmall(SizeMissmatch),
+    ToSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
     /// The provider buffer is too small. Returns the passed slice length and expected minimum size
-    FromSliceTooSmall(SizeMissmatch),
+    FromSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
     /// The [zerocopy] library failed to write to bytes
     ZeroCopyToError,
     ZeroCopyFromError,
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+impl Display for ByteConversionError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                write!(
+                    f,
+                    "target slice with size {} is too small, expected size of at least {}",
+                    found, expected
+                )
+            }
+            ByteConversionError::FromSliceTooSmall { found, expected } => {
+                write!(
+                    f,
+                    "source slice with size {} too small, expected at least {} bytes",
+                    found, expected
+                )
+            }
+            ByteConversionError::ZeroCopyToError => {
+                write!(f, "zerocopy serialization error")
+            }
+            ByteConversionError::ZeroCopyFromError => {
+                write!(f, "zerocopy deserialization error")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for ByteConversionError {}
+
+/// CCSDS packet type enumeration.
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum PacketType {
     Tm = 0,
     Tc = 1,
@@ -99,7 +160,8 @@ pub fn packet_type_in_raw_packet_id(packet_id: u16) -> PacketType {
     PacketType::try_from((packet_id >> 12) as u8 & 0b1).unwrap()
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum SequenceFlags {
     ContinuationSegment = 0b00,
     FirstSegment = 0b01,
@@ -123,21 +185,59 @@ impl TryFrom<u8> for SequenceFlags {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+/// Abstraction for the CCSDS Packet ID, which forms the last thirteen bits
+/// of the first two bytes in the CCSDS primary header.
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PacketId {
     pub ptype: PacketType,
     pub sec_header_flag: bool,
     apid: u16,
 }
 
-impl PacketId {
-    pub fn new(ptype: PacketType, sec_header_flag: bool, apid: u16) -> Option<PacketId> {
-        let mut pid = PacketId {
-            ptype,
-            sec_header_flag,
+impl Default for PacketId {
+    fn default() -> Self {
+        PacketId {
+            ptype: PacketType::Tm,
+            sec_header_flag: false,
             apid: 0,
-        };
-        pid.set_apid(apid).then_some(pid)
+        }
+    }
+}
+
+impl PacketId {
+    pub const fn const_tc(sec_header: bool, apid: u16) -> Self {
+        Self::const_new(PacketType::Tc, sec_header, apid)
+    }
+
+    pub const fn const_tm(sec_header: bool, apid: u16) -> Self {
+        Self::const_new(PacketType::Tm, sec_header, apid)
+    }
+
+    pub fn tc(sec_header: bool, apid: u16) -> Option<Self> {
+        Self::new(PacketType::Tc, sec_header, apid)
+    }
+
+    pub fn tm(sec_header: bool, apid: u16) -> Option<Self> {
+        Self::new(PacketType::Tm, sec_header, apid)
+    }
+
+    pub const fn const_new(ptype: PacketType, sec_header: bool, apid: u16) -> Self {
+        if apid > MAX_APID {
+            panic!("APID too large");
+        }
+        PacketId {
+            ptype,
+            sec_header_flag: sec_header,
+            apid,
+        }
+    }
+
+    pub fn new(ptype: PacketType, sec_header_flag: bool, apid: u16) -> Option<PacketId> {
+        if apid > MAX_APID {
+            return None;
+        }
+        Some(PacketId::const_new(ptype, sec_header_flag, apid))
     }
 
     /// Set a new Application Process ID (APID). If the passed number is invalid, the APID will
@@ -170,27 +270,41 @@ impl From<u16> for PacketId {
     }
 }
 
-#[derive(Serialize, Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+/// Abstraction for the CCSDS Packet Sequence Control (PSC) field which is the
+/// third and the fourth byte in the CCSDS primary header.
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct PacketSequenceCtrl {
     pub seq_flags: SequenceFlags,
     seq_count: u16,
 }
 
 impl PacketSequenceCtrl {
-    /// Returns [None] if the passed sequence count exceeds [MAX_SEQ_COUNT]
-    pub fn new(seq_flags: SequenceFlags, seq_count: u16) -> Option<PacketSequenceCtrl> {
-        let mut psc = PacketSequenceCtrl {
+    /// const variant of [PacketSequenceCtrl::new], but panics if the sequence count exceeds
+    /// [MAX_SEQ_COUNT].
+    const fn const_new(seq_flags: SequenceFlags, seq_count: u16) -> PacketSequenceCtrl {
+        if seq_count > MAX_SEQ_COUNT {
+            panic!("Sequence count too large");
+        }
+        PacketSequenceCtrl {
             seq_flags,
-            seq_count: 0,
-        };
-        psc.set_seq_count(seq_count).then_some(psc)
+            seq_count,
+        }
+    }
+
+    /// Returns [None] if the passed sequence count exceeds [MAX_SEQ_COUNT].
+    pub fn new(seq_flags: SequenceFlags, seq_count: u16) -> Option<PacketSequenceCtrl> {
+        if seq_count > MAX_SEQ_COUNT {
+            return None;
+        }
+        Some(PacketSequenceCtrl::const_new(seq_flags, seq_count))
     }
     pub fn raw(&self) -> u16 {
         ((self.seq_flags as u16) << 14) | self.seq_count
     }
 
     /// Set a new sequence count. If the passed number is invalid, the sequence count will not be
-    /// set and false will be returned. The maximum allowed value for the 14-bit field is 16383
+    /// set and false will be returned. The maximum allowed value for the 14-bit field is 16383.
     pub fn set_seq_count(&mut self, ssc: u16) -> bool {
         if ssc > MAX_SEQ_COUNT {
             return false;
@@ -231,7 +345,7 @@ macro_rules! sph_from_other {
 const SSC_MASK: u16 = 0x3FFF;
 const VERSION_MASK: u16 = 0xE000;
 
-/// Generic trait to access fields of a CCSDS space packet header according to CCSDS 133.0-B-2
+/// Generic trait to access fields of a CCSDS space packet header according to CCSDS 133.0-B-2.
 pub trait CcsdsPacket {
     fn ccsds_version(&self) -> u8;
     fn packet_id(&self) -> PacketId;
@@ -245,7 +359,7 @@ pub trait CcsdsPacket {
     }
 
     /// Retrieve 13 bit Packet Identification field. Can usually be retrieved with a bitwise AND
-    /// of the first 2 bytes with 0x1FFF
+    /// of the first 2 bytes with 0x1FFF.
     #[inline]
     fn packet_id_raw(&self) -> u16 {
         self.packet_id().raw()
@@ -256,8 +370,8 @@ pub trait CcsdsPacket {
         self.psc().raw()
     }
 
+    /// Retrieve Packet Type (TM: 0, TC: 1).
     #[inline]
-    /// Retrieve Packet Type (TM: 0, TC: 1)
     fn ptype(&self) -> PacketType {
         // This call should never fail because only 0 and 1 can be passed to the try_from call
         self.packet_id().ptype
@@ -274,13 +388,13 @@ pub trait CcsdsPacket {
     }
 
     /// Retrieve the secondary header flag. Returns true if a secondary header is present
-    /// and false if it is not
+    /// and false if it is not.
     #[inline]
     fn sec_header_flag(&self) -> bool {
         self.packet_id().sec_header_flag
     }
 
-    /// Retrieve Application Process ID
+    /// Retrieve Application Process ID.
     #[inline]
     fn apid(&self) -> u16 {
         self.packet_id().apid
@@ -308,16 +422,18 @@ pub trait CcsdsPrimaryHeader {
     ) -> Self;
 }
 
-/// Space Packet Primary Header according to CCSDS 133.0-B-2
+/// Space Packet Primary Header according to CCSDS 133.0-B-2.
 ///
 /// # Arguments
 ///
-/// * `version` - CCSDS version field, occupies the first 3 bits of the raw header
+/// * `version` - CCSDS version field, occupies the first 3 bits of the raw header. Will generally
+///    be set to 0b000 in all constructors provided by this crate.
 /// * `packet_id` - Packet Identifier, which can also be used as a start marker. Occupies the last
 ///    13 bits of the first two bytes of the raw header
 /// * `psc` - Packet Sequence Control, occupies the third and fourth byte of the raw header
 /// * `data_len` - Data length field occupies the fifth and the sixth byte of the raw header
-#[derive(serde::Serialize, serde::Deserialize, Debug, PartialEq, Eq, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct SpHeader {
     pub version: u8,
     pub packet_id: PacketId,
@@ -326,63 +442,104 @@ pub struct SpHeader {
 }
 
 impl Default for SpHeader {
+    /// The default function sets the sequence flag field to [SequenceFlags::Unsegmented]. The data
+    /// length field is set to 1, which denotes an empty space packets.
     fn default() -> Self {
         SpHeader {
             version: 0,
-            packet_id: PacketId {
-                ptype: PacketType::Tm,
-                apid: 0,
-                sec_header_flag: false,
-            },
+            packet_id: PacketId::default(),
             psc: PacketSequenceCtrl {
                 seq_flags: SequenceFlags::Unsegmented,
                 seq_count: 0,
             },
-            data_len: 0,
+            data_len: 1,
         }
     }
 }
+
 impl SpHeader {
-    /// Create a new Space Packet Header instance which can be used to create generic
-    /// Space Packets. This will return [None] if the APID or sequence count argument
-    /// exceed [MAX_APID] or [MAX_SEQ_COUNT] respectively.
-    pub fn new(
+    pub const fn new(packet_id: PacketId, psc: PacketSequenceCtrl, data_len: u16) -> Self {
+        Self {
+            version: 0,
+            packet_id,
+            psc,
+            data_len,
+        }
+    }
+
+    /// const variant of the [SpHeader::new_fron_single_fields] function. Panics if the passed
+    /// APID exceeds [MAX_APID] or the passed packet sequence count exceeds [MAX_SEQ_COUNT].
+    const fn const_new_from_single_fields(
         ptype: PacketType,
         sec_header: bool,
         apid: u16,
+        seq_flags: SequenceFlags,
+        seq_count: u16,
+        data_len: u16,
+    ) -> Self {
+        if seq_count > MAX_SEQ_COUNT {
+            panic!("Sequence count is too large");
+        }
+        if apid > MAX_APID {
+            panic!("APID is too large");
+        }
+        Self {
+            psc: PacketSequenceCtrl::const_new(seq_flags, seq_count),
+            packet_id: PacketId::const_new(ptype, sec_header, apid),
+            data_len,
+            version: 0,
+        }
+    }
+
+    /// Create a new Space Packet Header instance which can be used to create generic
+    /// Space Packets. This will return [None] if the APID or sequence count argument
+    /// exceed [MAX_APID] or [MAX_SEQ_COUNT] respectively. The version field is set to 0b000.
+    pub fn new_from_single_fields(
+        ptype: PacketType,
+        sec_header: bool,
+        apid: u16,
+        seq_flags: SequenceFlags,
         seq_count: u16,
         data_len: u16,
     ) -> Option<Self> {
         if seq_count > MAX_SEQ_COUNT || apid > MAX_APID {
             return None;
         }
-        let mut header = SpHeader::default();
-        header.packet_id.sec_header_flag = sec_header;
-        header.packet_id.apid = apid;
-        header.packet_id.ptype = ptype;
-        header.psc.seq_count = seq_count;
-        header.data_len = data_len;
-        Some(header)
+        Some(SpHeader::const_new_from_single_fields(
+            ptype, sec_header, apid, seq_flags, seq_count, data_len,
+        ))
     }
 
-    /// Helper function for telemetry space packet headers. The packet type  field will be
-    /// set accordingly.
-    pub fn tm(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::new(PacketType::Tm, false, apid, seq_count, data_len)
+    /// Helper function for telemetry space packet headers. The packet type field will be
+    /// set accordingly. The secondary header flag field is set to false.
+    pub fn tm(apid: u16, seq_flags: SequenceFlags, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::new_from_single_fields(PacketType::Tm, false, apid, seq_flags, seq_count, data_len)
     }
 
-    /// Helper function for telecommand space packet headers. The packet type  field will be
-    /// set accordingly.
-    pub fn tc(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
-        Self::new(PacketType::Tc, false, apid, seq_count, data_len)
+    /// Helper function for telemetry space packet headers. The packet type field will be
+    /// set accordingly. The secondary header flag field is set to false.
+    pub fn tc(apid: u16, seq_flags: SequenceFlags, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::new_from_single_fields(PacketType::Tc, false, apid, seq_flags, seq_count, data_len)
+    }
+
+    /// Variant of [SpHeader::tm] which sets the sequence flag field to [SequenceFlags::Unsegmented]
+    pub fn tm_unseg(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::tm(apid, SequenceFlags::Unsegmented, seq_count, data_len)
+    }
+
+    /// Variant of [SpHeader::tc] which sets the sequence flag field to [SequenceFlags::Unsegmented]
+    pub fn tc_unseg(apid: u16, seq_count: u16, data_len: u16) -> Option<Self> {
+        Self::tc(apid, SequenceFlags::Unsegmented, seq_count, data_len)
     }
 
     //noinspection RsTraitImplementation
     delegate!(to self.packet_id {
+        /// Returns [false] and fails if the APID exceeds [MAX_APID]
         pub fn set_apid(&mut self, apid: u16) -> bool;
     });
 
     delegate!(to self.psc {
+        /// Returns [false] and fails if the sequence count exceeds [MAX_SEQ_COUNT]
         pub fn set_seq_count(&mut self, seq_count: u16) -> bool;
     });
 
@@ -402,16 +559,38 @@ impl SpHeader {
         self.packet_id.ptype = packet_type;
     }
 
-    pub fn from_raw_slice(buf: &[u8]) -> Result<Self, ByteConversionError> {
-        if buf.len() < CCSDS_HEADER_LEN + 1 {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+    /// Create a struct from a raw slice where the fields have network endianness (big).
+    /// This function also returns the remaining part of the passed slice starting past the read
+    /// CCSDS header.
+    pub fn from_be_bytes(buf: &[u8]) -> Result<(Self, &[u8]), ByteConversionError> {
+        if buf.len() < CCSDS_HEADER_LEN {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
-                expected: CCSDS_HEADER_LEN + 1,
-            }));
+                expected: CCSDS_HEADER_LEN,
+            });
         }
         let zc_header = zc::SpHeader::from_bytes(&buf[0..CCSDS_HEADER_LEN])
             .ok_or(ByteConversionError::ZeroCopyFromError)?;
-        Ok(Self::from(zc_header))
+        Ok((Self::from(zc_header), &buf[CCSDS_HEADER_LEN..]))
+    }
+
+    /// Write the header to a raw buffer using big endian format. This function returns the
+    /// remaining part of the passed slice starting past the written CCSDS header.
+    pub fn write_to_be_bytes<'a>(
+        &self,
+        buf: &'a mut [u8],
+    ) -> Result<&'a mut [u8], ByteConversionError> {
+        if buf.len() < CCSDS_HEADER_LEN {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: CCSDS_HEADER_LEN,
+            });
+        }
+        let zc_header: zc::SpHeader = zc::SpHeader::from(*self);
+        zc_header
+            .to_bytes(&mut buf[0..CCSDS_HEADER_LEN])
+            .ok_or(ByteConversionError::ZeroCopyToError)?;
+        Ok(&mut buf[CCSDS_HEADER_LEN..])
     }
 }
 
@@ -462,9 +641,9 @@ sph_from_other!(SpHeader, crate::zc::SpHeader);
 pub mod zc {
     use crate::{CcsdsPacket, CcsdsPrimaryHeader, PacketId, PacketSequenceCtrl, VERSION_MASK};
     use zerocopy::byteorder::NetworkEndian;
-    use zerocopy::{AsBytes, FromBytes, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, Unaligned, U16};
 
-    #[derive(FromBytes, AsBytes, Unaligned, Debug)]
+    #[derive(FromBytes, FromZeroes, AsBytes, Unaligned, Debug)]
     #[repr(C)]
     pub struct SpHeader {
         version_packet_id: U16<NetworkEndian>,
@@ -540,23 +719,75 @@ pub mod zc {
     sph_from_other!(SpHeader, crate::SpHeader);
 }
 
-#[cfg(test)]
+#[cfg(all(test, feature = "std"))]
 mod tests {
-    #[cfg(feature = "std")]
+    #[cfg(feature = "serde")]
     use crate::CcsdsPrimaryHeader;
-    use crate::SpHeader;
     use crate::{
         packet_type_in_raw_packet_id, zc, CcsdsPacket, PacketId, PacketSequenceCtrl, PacketType,
-        SequenceFlags,
     };
+    use crate::{SequenceFlags, SpHeader};
     use alloc::vec;
-    #[cfg(not(feature = "std"))]
-    use num::pow;
-    #[cfg(feature = "std")]
     use num_traits::pow;
-    use postcard::from_bytes;
-    #[cfg(feature = "alloc")]
-    use postcard::to_allocvec;
+    #[cfg(feature = "serde")]
+    use postcard::{from_bytes, to_allocvec};
+
+    const CONST_SP: SpHeader = SpHeader::new(
+        PacketId::const_tc(true, 0x36),
+        PacketSequenceCtrl::const_new(SequenceFlags::ContinuationSegment, 0x88),
+        0x90,
+    );
+
+    const PACKET_ID_TM: PacketId = PacketId::const_tm(true, 0x22);
+
+    #[test]
+    fn verify_const_packet_id() {
+        assert_eq!(PACKET_ID_TM.apid(), 0x22);
+        assert_eq!(PACKET_ID_TM.sec_header_flag, true);
+        assert_eq!(PACKET_ID_TM.ptype, PacketType::Tm);
+        let const_tc_id = PacketId::const_tc(true, 0x23);
+        assert_eq!(const_tc_id.ptype, PacketType::Tc);
+    }
+
+    #[test]
+    fn test_default_packet_id() {
+        let id_default = PacketId::default();
+        assert_eq!(id_default.ptype, PacketType::Tm);
+        assert_eq!(id_default.apid, 0x000);
+        assert_eq!(id_default.sec_header_flag, false);
+    }
+
+    #[test]
+    fn test_packet_id_ctors() {
+        let packet_id = PacketId::new(PacketType::Tc, true, 0x1ff);
+        assert!(packet_id.is_some());
+        let packet_id = packet_id.unwrap();
+        assert_eq!(packet_id.apid(), 0x1ff);
+        assert_eq!(packet_id.ptype, PacketType::Tc);
+        assert_eq!(packet_id.sec_header_flag, true);
+        let packet_id_tc = PacketId::tc(true, 0x1ff);
+        assert!(packet_id_tc.is_some());
+        let packet_id_tc = packet_id_tc.unwrap();
+        assert_eq!(packet_id_tc, packet_id);
+        let packet_id_tm = PacketId::tm(true, 0x2ff);
+        assert!(packet_id_tm.is_some());
+        let packet_id_tm = packet_id_tm.unwrap();
+        assert_eq!(packet_id_tm.sec_header_flag, true);
+        assert_eq!(packet_id_tm.ptype, PacketType::Tm);
+        assert_eq!(packet_id_tm.apid, 0x2ff);
+    }
+
+    #[test]
+    fn verify_const_sp_header() {
+        assert_eq!(CONST_SP.sec_header_flag(), true);
+        assert_eq!(CONST_SP.apid(), 0x36);
+        assert_eq!(
+            CONST_SP.sequence_flags(),
+            SequenceFlags::ContinuationSegment
+        );
+        assert_eq!(CONST_SP.seq_count(), 0x88);
+        assert_eq!(CONST_SP.data_len, 0x90);
+    }
 
     #[test]
     fn test_seq_flag_helpers() {
@@ -639,9 +870,9 @@ mod tests {
     }
 
     #[test]
-    #[cfg(feature = "std")]
+    #[cfg(feature = "serde")]
     fn test_serde_sph() {
-        let sp_header = SpHeader::tc(0x42, 12, 0).expect("Error creating SP header");
+        let sp_header = SpHeader::tc_unseg(0x42, 12, 0).expect("Error creating SP header");
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert!(sp_header.is_tc());
         assert!(!sp_header.sec_header_flag());
@@ -663,7 +894,7 @@ mod tests {
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert_eq!(sp_header.data_len, 0);
 
-        let sp_header = SpHeader::tm(0x7, 22, 36).expect("Error creating SP header");
+        let sp_header = SpHeader::tm_unseg(0x7, 22, 36).expect("Error creating SP header");
         assert_eq!(sp_header.ccsds_version(), 0b000);
         assert!(sp_header.is_tm());
         assert!(!sp_header.sec_header_flag());
@@ -694,28 +925,69 @@ mod tests {
     }
 
     #[test]
-    fn test_sp_header_setters() {
-        let mut sp_header = SpHeader::tc(0x42, 12, 0).expect("Error creating SP header");
-        assert_eq!(sp_header.apid(), 0x42);
+    fn test_setters() {
+        let sp_header = SpHeader::tc(0x42, SequenceFlags::Unsegmented, 25, 0);
+        assert!(sp_header.is_some());
+        let mut sp_header = sp_header.unwrap();
         sp_header.set_apid(0x12);
         assert_eq!(sp_header.apid(), 0x12);
-
         sp_header.set_sec_header_flag();
         assert!(sp_header.sec_header_flag());
         sp_header.clear_sec_header_flag();
         assert!(!sp_header.sec_header_flag());
-        sp_header.set_seq_count(0x45);
-        assert_eq!(sp_header.seq_count(), 0x45);
         assert_eq!(sp_header.ptype(), PacketType::Tc);
         sp_header.set_packet_type(PacketType::Tm);
         assert_eq!(sp_header.ptype(), PacketType::Tm);
+        sp_header.set_seq_count(0x45);
+        assert_eq!(sp_header.seq_count(), 0x45);
+    }
+
+    #[test]
+    fn test_tc_ctor() {
+        let sp_header = SpHeader::tc(0x42, SequenceFlags::Unsegmented, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tc, &sp_header);
+    }
+
+    #[test]
+    fn test_tc_ctor_unseg() {
+        let sp_header = SpHeader::tc_unseg(0x42, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tc, &sp_header);
+    }
+
+    #[test]
+    fn test_tm_ctor() {
+        let sp_header = SpHeader::tm(0x42, SequenceFlags::Unsegmented, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tm, &sp_header);
+    }
+
+    #[test]
+    fn test_tm_ctor_unseg() {
+        let sp_header = SpHeader::tm_unseg(0x42, 25, 0);
+        assert!(sp_header.is_some());
+        let sp_header = sp_header.unwrap();
+        verify_sp_fields(PacketType::Tm, &sp_header);
+    }
+
+    fn verify_sp_fields(ptype: PacketType, sp_header: &SpHeader) {
+        assert_eq!(sp_header.ptype(), ptype);
+        assert_eq!(sp_header.sequence_flags(), SequenceFlags::Unsegmented);
+        assert_eq!(sp_header.apid(), 0x42);
+        assert_eq!(sp_header.seq_count(), 25);
+        assert_eq!(sp_header.data_len(), 0);
     }
 
     #[test]
     fn test_zc_sph() {
         use zerocopy::AsBytes;
 
-        let sp_header = SpHeader::tc(0x7FF, pow(2, 14) - 1, 0).expect("Error creating SP header");
+        let sp_header =
+            SpHeader::tc_unseg(0x7FF, pow(2, 14) - 1, 0).expect("Error creating SP header");
         assert_eq!(sp_header.ptype(), PacketType::Tc);
         assert_eq!(sp_header.apid(), 0x7FF);
         assert_eq!(sp_header.data_len(), 0);

src/tc.rs

@@ -1,739 +0,0 @@
-//! This module contains all components required to create a ECSS PUS C telecommand 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/).
-//!
-//! # Examples
-//!
-//! ```rust
-//! use spacepackets::{CcsdsPacket, SpHeader};
-//! use spacepackets::tc::{PusTc, PusTcSecondaryHeader};
-//! use spacepackets::ecss::PusPacket;
-//!
-//! // Create a ping telecommand with no user application data
-//! let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
-//! let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
-//! let pus_tc = PusTc::new(&mut sph, tc_header, None, true);
-//! println!("{:?}", pus_tc);
-//! assert_eq!(pus_tc.service(), 17);
-//! assert_eq!(pus_tc.subservice(), 1);
-//! assert_eq!(pus_tc.apid(), 0x02);
-//!
-//! // Serialize TC into a raw buffer
-//! let mut test_buf: [u8; 32] = [0; 32];
-//! let size = pus_tc
-//!     .write_to_bytes(test_buf.as_mut_slice())
-//!     .expect("Error writing TC to buffer");
-//! assert_eq!(size, 13);
-//! println!("{:?}", &test_buf[0..size]);
-//!
-//! // Deserialize from the raw byte representation
-//! let pus_tc_deserialized = PusTc::from_bytes(&test_buf).expect("Deserialization failed");
-//! assert_eq!(pus_tc.service(), 17);
-//! assert_eq!(pus_tc.subservice(), 1);
-//! assert_eq!(pus_tc.apid(), 0x02);
-//! ```
-use crate::ecss::{
-    ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
-    verify_crc16_from_raw, CrcType, PusError, PusPacket, PusVersion, CRC_CCITT_FALSE,
-};
-use crate::SpHeader;
-use crate::{
-    ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SizeMissmatch, CCSDS_HEADER_LEN,
-};
-use core::mem::size_of;
-use delegate::delegate;
-use serde::{Deserialize, Serialize};
-use zerocopy::AsBytes;
-
-#[cfg(feature = "alloc")]
-use alloc::vec::Vec;
-
-/// PUS C secondary header length is fixed
-pub const PUC_TC_SECONDARY_HEADER_LEN: usize = size_of::<zc::PusTcSecondaryHeader>();
-pub const PUS_TC_MIN_LEN_WITHOUT_APP_DATA: usize =
-    CCSDS_HEADER_LEN + PUC_TC_SECONDARY_HEADER_LEN + size_of::<CrcType>();
-const PUS_VERSION: PusVersion = PusVersion::PusC;
-
-#[derive(Copy, Clone, PartialEq, Debug)]
-enum AckOpts {
-    Acceptance = 0b1000,
-    Start = 0b0100,
-    Progress = 0b0010,
-    Completion = 0b0001,
-}
-
-pub const ACK_ALL: u8 = AckOpts::Acceptance as u8
-    | AckOpts::Start as u8
-    | AckOpts::Progress as u8
-    | AckOpts::Completion as u8;
-
-pub trait PusTcSecondaryHeaderT {
-    fn pus_version(&self) -> PusVersion;
-    fn ack_flags(&self) -> u8;
-    fn service(&self) -> u8;
-    fn subservice(&self) -> u8;
-    fn source_id(&self) -> u16;
-}
-
-pub mod zc {
-    use crate::ecss::{PusError, PusVersion};
-    use crate::tc::PusTcSecondaryHeaderT;
-    use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
-
-    #[derive(FromBytes, AsBytes, Unaligned)]
-    #[repr(C)]
-    pub struct PusTcSecondaryHeader {
-        version_ack: u8,
-        service: u8,
-        subservice: u8,
-        source_id: U16<NetworkEndian>,
-    }
-
-    impl TryFrom<crate::tc::PusTcSecondaryHeader> for PusTcSecondaryHeader {
-        type Error = PusError;
-        fn try_from(value: crate::tc::PusTcSecondaryHeader) -> Result<Self, Self::Error> {
-            if value.version != PusVersion::PusC {
-                return Err(PusError::VersionNotSupported(value.version));
-            }
-            Ok(PusTcSecondaryHeader {
-                version_ack: ((value.version as u8) << 4) | value.ack,
-                service: value.service,
-                subservice: value.subservice,
-                source_id: U16::from(value.source_id),
-            })
-        }
-    }
-
-    impl PusTcSecondaryHeaderT for PusTcSecondaryHeader {
-        fn pus_version(&self) -> PusVersion {
-            PusVersion::try_from(self.version_ack >> 4 & 0b1111).unwrap_or(PusVersion::Invalid)
-        }
-
-        fn ack_flags(&self) -> u8 {
-            self.version_ack & 0b1111
-        }
-
-        fn service(&self) -> u8 {
-            self.service
-        }
-
-        fn subservice(&self) -> u8 {
-            self.subservice
-        }
-
-        fn source_id(&self) -> u16 {
-            self.source_id.get()
-        }
-    }
-
-    impl PusTcSecondaryHeader {
-        pub fn write_to_bytes(&self, slice: &mut [u8]) -> Option<()> {
-            self.write_to(slice)
-        }
-
-        pub fn from_bytes(slice: &[u8]) -> Option<Self> {
-            Self::read_from(slice)
-        }
-    }
-}
-
-#[derive(PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Debug)]
-pub struct PusTcSecondaryHeader {
-    pub service: u8,
-    pub subservice: u8,
-    pub source_id: u16,
-    pub ack: u8,
-    pub version: PusVersion,
-}
-
-impl PusTcSecondaryHeaderT for PusTcSecondaryHeader {
-    fn pus_version(&self) -> PusVersion {
-        self.version
-    }
-
-    fn ack_flags(&self) -> u8 {
-        self.ack
-    }
-
-    fn service(&self) -> u8 {
-        self.service
-    }
-
-    fn subservice(&self) -> u8 {
-        self.subservice
-    }
-
-    fn source_id(&self) -> u16 {
-        self.source_id
-    }
-}
-
-impl TryFrom<zc::PusTcSecondaryHeader> for PusTcSecondaryHeader {
-    type Error = ();
-
-    fn try_from(value: zc::PusTcSecondaryHeader) -> Result<Self, Self::Error> {
-        Ok(PusTcSecondaryHeader {
-            service: value.service(),
-            subservice: value.subservice(),
-            source_id: value.source_id(),
-            ack: value.ack_flags(),
-            version: PUS_VERSION,
-        })
-    }
-}
-
-impl PusTcSecondaryHeader {
-    pub fn new_simple(service: u8, subservice: u8) -> Self {
-        PusTcSecondaryHeader {
-            service,
-            subservice,
-            ack: ACK_ALL,
-            source_id: 0,
-            version: PusVersion::PusC,
-        }
-    }
-
-    pub fn new(service: u8, subservice: u8, ack: u8, source_id: u16) -> Self {
-        PusTcSecondaryHeader {
-            service,
-            subservice,
-            ack: ack & 0b1111,
-            source_id,
-            version: PusVersion::PusC,
-        }
-    }
-}
-
-/// This class models a PUS telecommand. It is the primary data structure to generate the raw byte
-/// representation of a PUS telecommand or to deserialize from one from raw bytes.
-///
-/// This class also derives the [serde::Serialize] and [serde::Deserialize] trait which allows
-/// to send around TC packets in a raw byte format using a serde provider like
-/// [postcard](https://docs.rs/postcard/latest/postcard/).
-///
-/// There is no spare bytes support yet.
-#[derive(PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Debug)]
-pub struct PusTc<'slice> {
-    sp_header: SpHeader,
-    pub sec_header: PusTcSecondaryHeader,
-    /// If this is set to false, a manual call to [PusTc::calc_own_crc16] or
-    /// [PusTc::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
-    pub calc_crc_on_serialization: bool,
-    #[serde(skip)]
-    raw_data: Option<&'slice [u8]>,
-    app_data: Option<&'slice [u8]>,
-    crc16: Option<u16>,
-}
-
-impl<'slice> PusTc<'slice> {
-    /// Generates a new struct instance.
-    ///
-    /// # Arguments
-    ///
-    /// * `sp_header` - Space packet header information. The correct packet type will be set
-    ///     automatically
-    /// * `sec_header` - Information contained in the data field header, including the service
-    ///     and subservice type
-    /// * `app_data` - Custom application data
-    /// * `set_ccsds_len` - Can be used to automatically update the CCSDS space packet data length
-    ///     field. If this is not set to true, [PusTc::update_ccsds_data_len] can be called to set
-    ///     the correct value to this field manually
-    pub fn new(
-        sp_header: &mut SpHeader,
-        sec_header: PusTcSecondaryHeader,
-        app_data: Option<&'slice [u8]>,
-        set_ccsds_len: bool,
-    ) -> Self {
-        sp_header.set_packet_type(PacketType::Tc);
-        sp_header.set_sec_header_flag();
-        let mut pus_tc = PusTc {
-            sp_header: *sp_header,
-            raw_data: None,
-            app_data,
-            sec_header,
-            calc_crc_on_serialization: true,
-            crc16: None,
-        };
-        if set_ccsds_len {
-            pus_tc.update_ccsds_data_len();
-        }
-        pus_tc
-    }
-
-    /// Simplified version of the [PusTc::new] function which allows to only specify service and
-    /// subservice instead of the full PUS TC secondary header
-    pub fn new_simple(
-        sph: &mut SpHeader,
-        service: u8,
-        subservice: u8,
-        app_data: Option<&'slice [u8]>,
-        set_ccsds_len: bool,
-    ) -> Self {
-        Self::new(
-            sph,
-            PusTcSecondaryHeader::new(service, subservice, ACK_ALL, 0),
-            app_data,
-            set_ccsds_len,
-        )
-    }
-
-    pub fn len_packed(&self) -> usize {
-        let mut length = PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
-        if let Some(app_data) = self.app_data {
-            length += app_data.len();
-        }
-        length
-    }
-
-    pub fn set_ack_field(&mut self, ack: u8) -> bool {
-        if ack > 0b1111 {
-            return false;
-        }
-        self.sec_header.ack = ack & 0b1111;
-        true
-    }
-
-    pub fn set_source_id(&mut self, source_id: u16) {
-        self.sec_header.source_id = source_id;
-    }
-
-    sp_header_impls!();
-
-    /// Calculate the CCSDS space packet data length field and sets it
-    /// This is called automatically if the `set_ccsds_len` argument in the [PusTc::new] call was
-    /// used.
-    /// If this was not done or the application data is set or changed after construction,
-    /// this function needs to be called to ensure that the data length field of the CCSDS header
-    /// is set correctly
-    pub fn update_ccsds_data_len(&mut self) {
-        self.sp_header.data_len =
-            self.len_packed() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
-    }
-
-    /// This function should be called before the TC packet is serialized if
-    /// [PusTc::calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
-    pub fn calc_own_crc16(&mut self) {
-        let mut digest = CRC_CCITT_FALSE.digest();
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        digest.update(sph_zc.as_bytes());
-        let pus_tc_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
-        digest.update(pus_tc_header.as_bytes());
-        if let Some(app_data) = self.app_data {
-            digest.update(app_data);
-        }
-        self.crc16 = Some(digest.finalize())
-    }
-
-    /// This helper function calls both [PusTc.update_ccsds_data_len] and [PusTc.calc_own_crc16]
-    pub fn update_packet_fields(&mut self) {
-        self.update_ccsds_data_len();
-        self.calc_own_crc16();
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = 0;
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        let tc_header_len = size_of::<zc::PusTcSecondaryHeader>();
-        let total_size = self.len_packed();
-        if total_size > slice.len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: slice.len(),
-                expected: total_size,
-            })
-            .into());
-        }
-        sph_zc
-            .to_bytes(&mut slice[curr_idx..curr_idx + CCSDS_HEADER_LEN])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
-        sec_header
-            .write_to_bytes(&mut slice[curr_idx..curr_idx + tc_header_len])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-
-        curr_idx += tc_header_len;
-        if let Some(app_data) = self.app_data {
-            slice[curr_idx..curr_idx + app_data.len()].copy_from_slice(app_data);
-            curr_idx += app_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            0,
-            curr_idx,
-            slice,
-        )?;
-        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
-    #[cfg(feature = "alloc")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-    pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PusError> {
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        let mut appended_len = PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
-        if let Some(app_data) = self.app_data {
-            appended_len += app_data.len();
-        };
-        let start_idx = vec.len();
-        let mut ser_len = 0;
-        vec.extend_from_slice(sph_zc.as_bytes());
-        ser_len += sph_zc.as_bytes().len();
-        // The PUS version is hardcoded to PUS C
-        let pus_tc_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
-        vec.extend_from_slice(pus_tc_header.as_bytes());
-        ser_len += pus_tc_header.as_bytes().len();
-        if let Some(app_data) = self.app_data {
-            vec.extend_from_slice(app_data);
-            ser_len += app_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            start_idx,
-            ser_len,
-            &vec[start_idx..ser_len],
-        )?;
-        vec.extend_from_slice(crc16.to_be_bytes().as_slice());
-        Ok(appended_len)
-    }
-
-    /// Create a [PusTc] instance from a raw slice. On success, it returns a tuple containing
-    /// the instance and the found byte length of the packet
-    pub fn from_bytes(slice: &'slice [u8]) -> Result<(Self, usize), PusError> {
-        let raw_data_len = slice.len();
-        if raw_data_len < PUS_TC_MIN_LEN_WITHOUT_APP_DATA {
-            return Err(PusError::RawDataTooShort(raw_data_len));
-        }
-        let mut current_idx = 0;
-        let sph =
-            crate::zc::SpHeader::from_bytes(&slice[current_idx..current_idx + CCSDS_HEADER_LEN])
-                .ok_or(ByteConversionError::ZeroCopyFromError)?;
-        current_idx += CCSDS_HEADER_LEN;
-        let total_len = sph.total_len();
-        if raw_data_len < total_len || total_len < PUS_TC_MIN_LEN_WITHOUT_APP_DATA {
-            return Err(PusError::RawDataTooShort(raw_data_len));
-        }
-        let sec_header = zc::PusTcSecondaryHeader::from_bytes(
-            &slice[current_idx..current_idx + PUC_TC_SECONDARY_HEADER_LEN],
-        )
-        .ok_or(ByteConversionError::ZeroCopyFromError)?;
-        current_idx += PUC_TC_SECONDARY_HEADER_LEN;
-        let raw_data = &slice[0..total_len];
-        let pus_tc = PusTc {
-            sp_header: SpHeader::from(sph),
-            sec_header: PusTcSecondaryHeader::try_from(sec_header).unwrap(),
-            raw_data: Some(raw_data),
-            app_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
-            calc_crc_on_serialization: false,
-            crc16: Some(crc_from_raw_data(raw_data)?),
-        };
-        verify_crc16_from_raw(raw_data, pus_tc.crc16.expect("CRC16 invalid"))?;
-        Ok((pus_tc, total_len))
-    }
-
-    pub fn raw(&self) -> Option<&'slice [u8]> {
-        self.raw_data
-    }
-}
-
-//noinspection RsTraitImplementation
-impl CcsdsPacket for PusTc<'_> {
-    ccsds_impl!();
-}
-
-//noinspection RsTraitImplementation
-impl PusPacket for PusTc<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-    });
-
-    fn user_data(&self) -> Option<&[u8]> {
-        self.app_data
-    }
-
-    fn crc16(&self) -> Option<u16> {
-        self.crc16
-    }
-}
-
-//noinspection RsTraitImplementation
-impl PusTcSecondaryHeaderT for PusTc<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-        fn source_id(&self) -> u16;
-        fn ack_flags(&self) -> u8;
-    });
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::ecss::PusVersion::PusC;
-    use crate::ecss::{PusError, PusPacket};
-    use crate::tc::ACK_ALL;
-    use crate::tc::{PusTc, PusTcSecondaryHeader, PusTcSecondaryHeaderT};
-    use crate::{ByteConversionError, SpHeader};
-    use crate::{CcsdsPacket, SequenceFlags};
-    use alloc::vec::Vec;
-
-    fn base_ping_tc_full_ctor() -> PusTc<'static> {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
-        let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
-        PusTc::new(&mut sph, tc_header, None, true)
-    }
-
-    fn base_ping_tc_simple_ctor() -> PusTc<'static> {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
-        PusTc::new_simple(&mut sph, 17, 1, None, true)
-    }
-
-    fn base_ping_tc_simple_ctor_with_app_data(app_data: &'static [u8]) -> PusTc<'static> {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
-        PusTc::new_simple(&mut sph, 17, 1, Some(app_data), true)
-    }
-
-    #[test]
-    fn test_tc_fields() {
-        let pus_tc = base_ping_tc_full_ctor();
-        assert_eq!(pus_tc.crc16(), None);
-        verify_test_tc(&pus_tc, false, 13);
-    }
-
-    #[test]
-    fn test_serialization() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(size, 13);
-    }
-
-    #[test]
-    fn test_deserialization() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(size, 13);
-        let (tc_from_raw, size) =
-            PusTc::from_bytes(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(size, 13);
-        verify_test_tc(&tc_from_raw, false, 13);
-        assert!(tc_from_raw.user_data().is_none());
-        verify_test_tc_raw(&test_buf);
-        verify_crc_no_app_data(&test_buf);
-    }
-
-    #[test]
-    fn test_update_func() {
-        let mut sph = SpHeader::tc(0x02, 0x34, 0).unwrap();
-        let mut tc = PusTc::new_simple(&mut sph, 17, 1, None, false);
-        tc.calc_crc_on_serialization = false;
-        assert_eq!(tc.data_len(), 0);
-        tc.update_packet_fields();
-        assert_eq!(tc.data_len(), 6);
-    }
-    #[test]
-    fn test_deserialization_with_app_data() {
-        let pus_tc = base_ping_tc_simple_ctor_with_app_data(&[1, 2, 3]);
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(size, 16);
-        let (tc_from_raw, size) =
-            PusTc::from_bytes(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(size, 16);
-        verify_test_tc(&tc_from_raw, true, 16);
-        let user_data = tc_from_raw.user_data().unwrap();
-        assert_eq!(user_data[0], 1);
-        assert_eq!(user_data[1], 2);
-        assert_eq!(user_data[2], 3);
-    }
-
-    #[test]
-    #[cfg(feature = "alloc")]
-    fn test_vec_ser_deser() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_vec = Vec::new();
-        let size = pus_tc
-            .append_to_vec(&mut test_vec)
-            .expect("Error writing TC to vector");
-        assert_eq!(size, 13);
-        verify_test_tc_raw(&test_vec.as_slice());
-        verify_crc_no_app_data(&test_vec.as_slice());
-    }
-
-    #[test]
-    fn test_incorrect_crc() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        test_buf[12] = 0;
-        let res = PusTc::from_bytes(&test_buf);
-        assert!(res.is_err());
-        let err = res.unwrap_err();
-        assert!(matches!(err, PusError::IncorrectCrc { .. }));
-    }
-
-    #[test]
-    fn test_manual_crc_calculation() {
-        let mut pus_tc = base_ping_tc_simple_ctor();
-        pus_tc.calc_crc_on_serialization = false;
-        let mut test_buf: [u8; 32] = [0; 32];
-        pus_tc.calc_own_crc16();
-        pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        verify_test_tc_raw(&test_buf);
-        verify_crc_no_app_data(&test_buf);
-    }
-
-    #[test]
-    fn test_manual_crc_calculation_no_calc_call() {
-        let mut pus_tc = base_ping_tc_simple_ctor();
-        pus_tc.calc_crc_on_serialization = false;
-        let mut test_buf: [u8; 32] = [0; 32];
-        let res = pus_tc.write_to_bytes(test_buf.as_mut_slice());
-        assert!(res.is_err());
-        let err = res.unwrap_err();
-        assert!(matches!(err, PusError::CrcCalculationMissing { .. }));
-    }
-
-    #[test]
-    fn test_with_application_data_vec() {
-        let pus_tc = base_ping_tc_simple_ctor_with_app_data(&[1, 2, 3]);
-        verify_test_tc(&pus_tc, true, 16);
-        let mut test_vec = Vec::new();
-        let size = pus_tc
-            .append_to_vec(&mut test_vec)
-            .expect("Error writing TC to vector");
-        assert_eq!(test_vec[11], 1);
-        assert_eq!(test_vec[12], 2);
-        assert_eq!(test_vec[13], 3);
-        assert_eq!(size, 16);
-    }
-
-    #[test]
-    fn test_write_buf_too_msall() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf = [0; 12];
-        let res = pus_tc.write_to_bytes(test_buf.as_mut_slice());
-        assert!(res.is_err());
-        let err = res.unwrap_err();
-        match err {
-            PusError::ByteConversionError(err) => match err {
-                ByteConversionError::ToSliceTooSmall(missmatch) => {
-                    assert_eq!(missmatch.expected, pus_tc.len_packed());
-                    assert_eq!(missmatch.found, 12);
-                }
-                _ => panic!("Unexpected error"),
-            },
-            _ => panic!("Unexpected error"),
-        }
-    }
-
-    #[test]
-    fn test_with_application_data_buf() {
-        let pus_tc = base_ping_tc_simple_ctor_with_app_data(&[1, 2, 3]);
-        verify_test_tc(&pus_tc, true, 16);
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(test_buf[11], 1);
-        assert_eq!(test_buf[12], 2);
-        assert_eq!(test_buf[13], 3);
-        assert_eq!(size, 16);
-    }
-
-    #[test]
-    fn test_custom_setters() {
-        let mut pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        pus_tc.set_apid(0x7ff);
-        pus_tc.set_seq_count(0x3fff);
-        pus_tc.set_ack_field(0b11);
-        pus_tc.set_source_id(0xffff);
-        pus_tc.set_seq_flags(SequenceFlags::Unsegmented);
-        assert_eq!(pus_tc.source_id(), 0xffff);
-        assert_eq!(pus_tc.seq_count(), 0x3fff);
-        assert_eq!(pus_tc.ack_flags(), 0b11);
-        assert_eq!(pus_tc.apid(), 0x7ff);
-        assert_eq!(pus_tc.sequence_flags(), SequenceFlags::Unsegmented);
-        pus_tc.calc_own_crc16();
-        pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(test_buf[0], 0x1f);
-        assert_eq!(test_buf[1], 0xff);
-        assert_eq!(test_buf[2], 0xff);
-        assert_eq!(test_buf[3], 0xff);
-        assert_eq!(test_buf[6], 0x23);
-        // Source ID 0
-        assert_eq!(test_buf[9], 0xff);
-        assert_eq!(test_buf[10], 0xff);
-    }
-
-    fn verify_test_tc(tc: &PusTc, has_user_data: bool, exp_full_len: usize) {
-        assert_eq!(PusPacket::service(tc), 17);
-        assert_eq!(PusPacket::subservice(tc), 1);
-        assert!(tc.sec_header_flag());
-        assert_eq!(PusPacket::pus_version(tc), PusC);
-        if !has_user_data {
-            assert_eq!(tc.user_data(), None);
-        }
-        assert_eq!(tc.seq_count(), 0x34);
-        assert_eq!(tc.source_id(), 0);
-        assert_eq!(tc.apid(), 0x02);
-        assert_eq!(tc.ack_flags(), ACK_ALL);
-        assert_eq!(tc.len_packed(), exp_full_len);
-        let mut comp_header = SpHeader::tc(0x02, 0x34, exp_full_len as u16 - 7).unwrap();
-        comp_header.set_sec_header_flag();
-        assert_eq!(tc.sp_header, comp_header);
-    }
-
-    fn verify_test_tc_raw(slice: &impl AsRef<[u8]>) {
-        // Reference comparison implementation:
-        // https://github.com/us-irs/py-spacepackets/blob/v0.13.0/tests/ecss/test_pus_tc.py
-        let slice = slice.as_ref();
-        // 0x1801 is the generic
-        assert_eq!(slice[0], 0x18);
-        // APID is 0x01
-        assert_eq!(slice[1], 0x02);
-        // Unsegmented packets
-        assert_eq!(slice[2], 0xc0);
-        // Sequence count 0x34
-        assert_eq!(slice[3], 0x34);
-        assert_eq!(slice[4], 0x00);
-        // Space data length of 6 equals total packet length of 13
-        assert_eq!(slice[5], 0x06);
-        // PUS Version C 0b0010 and ACK flags 0b1111
-        assert_eq!(slice[6], 0x2f);
-        // Service 17
-        assert_eq!(slice[7], 0x11);
-        // Subservice 1
-        assert_eq!(slice[8], 0x01);
-        // Source ID 0
-        assert_eq!(slice[9], 0x00);
-        assert_eq!(slice[10], 0x00);
-    }
-
-    fn verify_crc_no_app_data(slice: &impl AsRef<[u8]>) {
-        // Reference comparison implementation:
-        // https://github.com/us-irs/py-spacepackets/blob/v0.13.0/tests/ecss/test_pus_tc.py
-        let slice = slice.as_ref();
-        assert_eq!(slice[11], 0xee);
-        assert_eq!(slice[12], 0x63);
-    }
-}

src/time.rs

@@ -1,469 +0,0 @@
-//! CCSDS Time Code Formats according to [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
-use crate::{ByteConversionError, SizeMissmatch};
-use chrono::{DateTime, LocalResult, TimeZone, Utc};
-
-#[allow(unused_imports)]
-#[cfg(not(feature = "std"))]
-use num_traits::float::FloatCore;
-
-use crate::time::CcsdsTimeCodes::Cds;
-#[cfg(feature = "std")]
-use std::time::{SystemTime, SystemTimeError};
-
-pub const CDS_SHORT_LEN: usize = 7;
-pub const DAYS_CCSDS_TO_UNIX: i32 = -4383;
-pub const SECONDS_PER_DAY: u32 = 86400;
-
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
-pub enum CcsdsTimeCodes {
-    None = 0,
-    CucCcsdsEpoch = 0b001,
-    CucAgencyEpoch = 0b010,
-    Cds = 0b100,
-    Ccs = 0b101,
-}
-
-const CDS_SHORT_P_FIELD: u8 = (CcsdsTimeCodes::Cds as u8) << 4;
-
-impl TryFrom<u8> for CcsdsTimeCodes {
-    type Error = ();
-
-    fn try_from(value: u8) -> Result<Self, Self::Error> {
-        match value {
-            x if x == CcsdsTimeCodes::None as u8 => Ok(CcsdsTimeCodes::None),
-            x if x == CcsdsTimeCodes::CucCcsdsEpoch as u8 => Ok(CcsdsTimeCodes::CucCcsdsEpoch),
-            x if x == CcsdsTimeCodes::CucAgencyEpoch as u8 => Ok(CcsdsTimeCodes::CucAgencyEpoch),
-            x if x == CcsdsTimeCodes::Cds as u8 => Ok(CcsdsTimeCodes::Cds),
-            x if x == CcsdsTimeCodes::Ccs as u8 => Ok(CcsdsTimeCodes::Ccs),
-            _ => Err(()),
-        }
-    }
-}
-
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
-pub enum TimestampError {
-    /// Contains tuple where first value is the expected time code and the second
-    /// value is the found raw value
-    InvalidTimeCode(CcsdsTimeCodes, u8),
-    OtherPacketError(ByteConversionError),
-}
-
-#[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
-pub fn seconds_since_epoch() -> f64 {
-    SystemTime::now()
-        .duration_since(SystemTime::UNIX_EPOCH)
-        .expect("System time generation failed")
-        .as_secs_f64()
-}
-
-/// Convert UNIX days to CCSDS days
-///
-///  - CCSDS epoch: 1958 January 1
-///  - UNIX Epoch: 1970 January 1
-pub const fn unix_to_ccsds_days(unix_days: i32) -> i32 {
-    unix_days - DAYS_CCSDS_TO_UNIX
-}
-
-/// Convert CCSDS days to UNIX days
-///
-///  - CCSDS epoch: 1958 January 1
-///  - UNIX Epoch: 1970 January 1
-pub const fn ccsds_to_unix_days(ccsds_days: i32) -> i32 {
-    ccsds_days + DAYS_CCSDS_TO_UNIX
-}
-
-pub trait TimeWriter {
-    fn write_to_bytes(&self, bytes: &mut [u8]) -> Result<(), TimestampError>;
-}
-
-pub trait TimeReader {
-    fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError>
-    where
-        Self: Sized;
-}
-
-/// Trait for generic CCSDS time providers
-pub trait CcsdsTimeProvider {
-    fn len_as_bytes(&self) -> usize;
-
-    /// Returns the pfield of the time provider. The pfield can have one or two bytes depending
-    /// on the extension bit (first bit). The time provider should returns a tuple where the first
-    /// 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 unix_seconds(&self) -> i64;
-    fn date_time(&self) -> Option<DateTime<Utc>>;
-}
-
-/// This object is the abstraction for the CCSDS Day Segmented Time Code (CDS).
-///
-/// It has the capability to generate and read timestamps as specified in the CCSDS 301.0-B-4
-/// section 3.3
-///
-/// # Example
-///
-/// ```
-/// use spacepackets::time::{CdsShortTimeProvider, TimeWriter};
-/// use spacepackets::time::CcsdsTimeCodes::Cds;
-/// let timestamp_now = CdsShortTimeProvider::from_now().unwrap();
-/// let mut raw_stamp = [0; 7];
-/// timestamp_now.write_to_bytes(&mut raw_stamp).unwrap();
-/// assert_eq!((raw_stamp[0] >> 4) & 0b111, Cds as u8);
-/// ```
-#[derive(Debug, Copy, Clone, Default)]
-pub struct CdsShortTimeProvider {
-    ccsds_days: u16,
-    ms_of_day: u32,
-    unix_seconds: i64,
-    date_time: Option<DateTime<Utc>>,
-}
-
-impl CdsShortTimeProvider {
-    pub fn new(ccsds_days: u16, ms_of_day: u32) -> Self {
-        let provider = Self {
-            ccsds_days,
-            ms_of_day,
-            unix_seconds: 0,
-            date_time: None,
-        };
-        let unix_days_seconds =
-            ccsds_to_unix_days(ccsds_days as i32) as i64 * SECONDS_PER_DAY as i64;
-        provider.setup(unix_days_seconds as i64, ms_of_day.into())
-    }
-
-    #[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();
-        let secs_of_day = epoch % SECONDS_PER_DAY as u64;
-        let unix_days_seconds = epoch - secs_of_day;
-        let ms_of_day = secs_of_day * 1000 + now.subsec_millis() as u64;
-        let provider = Self {
-            ccsds_days: unix_to_ccsds_days((unix_days_seconds / SECONDS_PER_DAY as u64) as i32)
-                as u16,
-            ms_of_day: ms_of_day as u32,
-            unix_seconds: 0,
-            date_time: None,
-        };
-        Ok(provider.setup(unix_days_seconds as i64, ms_of_day))
-    }
-
-    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
-    pub fn update_from_now(&mut self) -> Result<(), SystemTimeError> {
-        let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
-        let epoch = now.as_secs();
-        let secs_of_day = epoch % SECONDS_PER_DAY as u64;
-        let unix_days_seconds = epoch - secs_of_day;
-        let ms_of_day = secs_of_day * 1000 + now.subsec_millis() as u64;
-        self.setup(unix_days_seconds as i64, ms_of_day);
-        Ok(())
-    }
-
-    fn setup(mut self, unix_days_seconds: i64, ms_of_day: u64) -> Self {
-        self.calc_unix_seconds(unix_days_seconds, ms_of_day);
-        self.calc_date_time((ms_of_day % 1000) as u32);
-        self
-    }
-
-    #[cfg(feature = "std")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
-    pub fn ms_of_day_using_sysclock() -> u32 {
-        Self::ms_of_day(seconds_since_epoch())
-    }
-
-    pub fn ms_of_day(seconds_since_epoch: f64) -> u32 {
-        let fraction_ms = seconds_since_epoch - seconds_since_epoch.floor();
-        let ms_of_day: u32 =
-            (((seconds_since_epoch.floor() as u32 % SECONDS_PER_DAY) * 1000) as f64 + fraction_ms)
-                .floor() as u32;
-        ms_of_day
-    }
-
-    fn calc_unix_seconds(&mut self, unix_days_seconds: i64, ms_of_day: u64) {
-        self.unix_seconds = unix_days_seconds;
-        let seconds_of_day = (ms_of_day / 1000) as i64;
-        if self.unix_seconds < 0 {
-            self.unix_seconds -= seconds_of_day;
-        } else {
-            self.unix_seconds += seconds_of_day;
-        }
-    }
-
-    fn calc_date_time(&mut self, ms_since_last_second: u32) {
-        assert!(ms_since_last_second < 1000, "Invalid MS since last second");
-        let ns_since_last_sec = ms_since_last_second * 1e6 as u32;
-        if let LocalResult::Single(val) = Utc.timestamp_opt(self.unix_seconds, ns_since_last_sec) {
-            self.date_time = Some(val);
-        } else {
-            self.date_time = None;
-        }
-    }
-}
-
-impl CcsdsTimeProvider for CdsShortTimeProvider {
-    fn len_as_bytes(&self) -> usize {
-        CDS_SHORT_LEN
-    }
-
-    fn p_field(&self) -> (usize, [u8; 2]) {
-        (1, [CDS_SHORT_P_FIELD, 0])
-    }
-
-    fn ccdsd_time_code(&self) -> CcsdsTimeCodes {
-        Cds
-    }
-
-    fn unix_seconds(&self) -> i64 {
-        self.unix_seconds
-    }
-
-    fn date_time(&self) -> Option<DateTime<Utc>> {
-        self.date_time
-    }
-}
-
-impl TimeWriter for CdsShortTimeProvider {
-    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<(), TimestampError> {
-        if buf.len() < self.len_as_bytes() {
-            return Err(TimestampError::OtherPacketError(
-                ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                    expected: self.len_as_bytes(),
-                    found: buf.len(),
-                }),
-            ));
-        }
-        buf[0] = CDS_SHORT_P_FIELD;
-        buf[1..3].copy_from_slice(self.ccsds_days.to_be_bytes().as_slice());
-        buf[3..7].copy_from_slice(self.ms_of_day.to_be_bytes().as_slice());
-        Ok(())
-    }
-}
-
-impl TimeReader for CdsShortTimeProvider {
-    fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError> {
-        if buf.len() < CDS_SHORT_LEN {
-            return Err(TimestampError::OtherPacketError(
-                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
-                    expected: CDS_SHORT_LEN,
-                    found: buf.len(),
-                }),
-            ));
-        }
-        let pfield = buf[0];
-        match CcsdsTimeCodes::try_from(pfield >> 4 & 0b111) {
-            Ok(cds_type) => match cds_type {
-                Cds => (),
-                _ => return Err(TimestampError::InvalidTimeCode(Cds, cds_type as u8)),
-            },
-            _ => return Err(TimestampError::InvalidTimeCode(Cds, pfield >> 4 & 0b111)),
-        };
-        let ccsds_days: u16 = u16::from_be_bytes(buf[1..3].try_into().unwrap());
-        let ms_of_day: u32 = u32::from_be_bytes(buf[3..7].try_into().unwrap());
-        Ok(Self::new(ccsds_days, ms_of_day))
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::time::TimestampError::{InvalidTimeCode, OtherPacketError};
-    use crate::ByteConversionError::{FromSliceTooSmall, ToSliceTooSmall};
-    use alloc::format;
-    use chrono::{Datelike, Timelike};
-
-    #[test]
-    fn test_creation() {
-        assert_eq!(unix_to_ccsds_days(DAYS_CCSDS_TO_UNIX), 0);
-        assert_eq!(ccsds_to_unix_days(0), DAYS_CCSDS_TO_UNIX);
-    }
-
-    #[cfg(feature = "std")]
-    #[test]
-    fn test_get_current_time() {
-        let sec_floats = seconds_since_epoch();
-        assert!(sec_floats > 0.0);
-    }
-
-    #[test]
-    fn test_time_stamp_zero_args() {
-        let time_stamper = CdsShortTimeProvider::new(0, 0);
-        assert_eq!(
-            time_stamper.unix_seconds(),
-            (DAYS_CCSDS_TO_UNIX * SECONDS_PER_DAY as i32) as i64
-        );
-        assert_eq!(time_stamper.ccdsd_time_code(), Cds);
-        assert_eq!(time_stamper.p_field(), (1, [(Cds as u8) << 4, 0]));
-        let date_time = time_stamper.date_time().unwrap();
-        assert_eq!(date_time.year(), 1958);
-        assert_eq!(date_time.month(), 1);
-        assert_eq!(date_time.day(), 1);
-        assert_eq!(date_time.hour(), 0);
-        assert_eq!(date_time.minute(), 0);
-        assert_eq!(date_time.second(), 0);
-    }
-
-    #[test]
-    fn test_time_stamp_unix_epoch() {
-        let time_stamper = CdsShortTimeProvider::new((-DAYS_CCSDS_TO_UNIX) as u16, 0);
-        assert_eq!(time_stamper.unix_seconds(), 0);
-        let date_time = time_stamper.date_time().unwrap();
-        assert_eq!(date_time.year(), 1970);
-        assert_eq!(date_time.month(), 1);
-        assert_eq!(date_time.day(), 1);
-        assert_eq!(date_time.hour(), 0);
-        assert_eq!(date_time.minute(), 0);
-        assert_eq!(date_time.second(), 0);
-    }
-
-    #[test]
-    fn test_write() {
-        let mut buf = [0; 16];
-        let time_stamper_0 = CdsShortTimeProvider::new(0, 0);
-        let mut res = time_stamper_0.write_to_bytes(&mut buf);
-        assert!(res.is_ok());
-        assert_eq!(buf[0], (CcsdsTimeCodes::Cds as u8) << 4);
-        assert_eq!(
-            u16::from_be_bytes(buf[1..3].try_into().expect("Byte conversion failed")),
-            0
-        );
-        assert_eq!(
-            u32::from_be_bytes(buf[3..7].try_into().expect("Byte conversion failed")),
-            0
-        );
-        let time_stamper_1 = CdsShortTimeProvider::new(u16::MAX - 1, u32::MAX - 1);
-        res = time_stamper_1.write_to_bytes(&mut buf);
-        assert!(res.is_ok());
-        assert_eq!(buf[0], (CcsdsTimeCodes::Cds as u8) << 4);
-        assert_eq!(
-            u16::from_be_bytes(buf[1..3].try_into().expect("Byte conversion failed")),
-            u16::MAX - 1
-        );
-        assert_eq!(
-            u32::from_be_bytes(buf[3..7].try_into().expect("Byte conversion failed")),
-            u32::MAX - 1
-        );
-    }
-
-    #[test]
-    fn test_faulty_write_buf_too_small() {
-        let mut buf = [0; 7];
-        let time_stamper = CdsShortTimeProvider::new(u16::MAX - 1, u32::MAX - 1);
-        for i in 0..6 {
-            let res = time_stamper.write_to_bytes(&mut buf[0..i]);
-            assert!(res.is_err());
-            match res.unwrap_err() {
-                OtherPacketError(ToSliceTooSmall(missmatch)) => {
-                    assert_eq!(missmatch.found, i);
-                    assert_eq!(missmatch.expected, 7);
-                }
-                _ => panic!(
-                    "{}",
-                    format!("Invalid error {:?} detected", res.unwrap_err())
-                ),
-            }
-        }
-    }
-
-    #[test]
-    fn test_faulty_read_buf_too_small() {
-        let buf = [0; 7];
-        for i in 0..6 {
-            let res = CdsShortTimeProvider::from_bytes(&buf[0..i]);
-            assert!(res.is_err());
-            match res.unwrap_err() {
-                InvalidTimeCode(_, _) => {
-                    panic!("Unexpected error");
-                }
-                OtherPacketError(e) => match e {
-                    FromSliceTooSmall(missmatch) => {
-                        assert_eq!(missmatch.found, i);
-                        assert_eq!(missmatch.expected, 7);
-                    }
-                    _ => panic!("{}", format!("Invalid error {:?} detected", e)),
-                },
-            }
-        }
-    }
-
-    #[test]
-    fn test_faulty_invalid_pfield() {
-        let mut buf = [0; 16];
-        let time_stamper_0 = CdsShortTimeProvider::new(0, 0);
-        let res = time_stamper_0.write_to_bytes(&mut buf);
-        assert!(res.is_ok());
-        buf[0] = 0;
-        let res = CdsShortTimeProvider::from_bytes(&buf);
-        assert!(res.is_err());
-        let err = res.unwrap_err();
-        match err {
-            InvalidTimeCode(code, raw) => {
-                assert_eq!(code, Cds);
-                assert_eq!(raw, 0);
-            }
-            OtherPacketError(_) => {}
-        }
-    }
-
-    #[test]
-    fn test_reading() {
-        let mut buf = [0; 16];
-        let time_stamper = CdsShortTimeProvider::new(u16::MAX - 1, u32::MAX - 1);
-        let res = time_stamper.write_to_bytes(&mut buf);
-        assert!(res.is_ok());
-        assert_eq!(buf[0], (CcsdsTimeCodes::Cds as u8) << 4);
-        assert_eq!(
-            u16::from_be_bytes(buf[1..3].try_into().expect("Byte conversion failed")),
-            u16::MAX - 1
-        );
-        assert_eq!(
-            u32::from_be_bytes(buf[3..7].try_into().expect("Byte conversion failed")),
-            u32::MAX - 1
-        );
-
-        let read_stamp = CdsShortTimeProvider::from_bytes(&buf).expect("Reading timestamp failed");
-        assert_eq!(read_stamp.ccsds_days, u16::MAX - 1);
-        assert_eq!(read_stamp.ms_of_day, u32::MAX - 1);
-    }
-
-    #[cfg(feature = "std")]
-    #[test]
-    fn test_time_now() {
-        let timestamp_now = CdsShortTimeProvider::from_now().unwrap();
-        let compare_stamp = Utc::now();
-        let dt = timestamp_now.date_time().unwrap();
-        if compare_stamp.year() > dt.year() {
-            assert_eq!(compare_stamp.year() - dt.year(), 1);
-        } else {
-            assert_eq!(dt.year(), compare_stamp.year());
-        }
-        generic_dt_property_equality_check(dt.month(), compare_stamp.month(), 1, 12);
-
-        assert_eq!(dt.day(), compare_stamp.day());
-        if compare_stamp.day() < dt.day() {
-            assert!(dt.day() >= 28);
-            assert_eq!(compare_stamp.day(), 1);
-        } else if compare_stamp.day() > dt.day() {
-            assert_eq!(compare_stamp.day() - dt.day(), 1);
-        } else {
-            assert_eq!(compare_stamp.day(), dt.day());
-        }
-        generic_dt_property_equality_check(dt.hour(), compare_stamp.hour(), 0, 23);
-        generic_dt_property_equality_check(dt.minute(), compare_stamp.minute(), 0, 59);
-    }
-
-    #[cfg(feature = "std")]
-    fn generic_dt_property_equality_check(first: u32, second: u32, start: u32, end: u32) {
-        if second < first {
-            assert_eq!(second, start);
-            assert_eq!(first, end);
-        } else if second > first {
-            assert_eq!(second - first, 1);
-        } else {
-            assert_eq!(first, second);
-        }
-    }
-}

src/time/ascii.rs

@@ -0,0 +1,130 @@
+//! Module to generate the ASCII timecodes specified in
+//! [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf) section 3.5 .
+//! See [chrono::DateTime::format] for a usage example of the generated
+//! [chrono::format::DelayedFormat] structs.
+#[cfg(feature = "alloc")]
+use chrono::{
+    format::{DelayedFormat, StrftimeItems},
+    DateTime, Utc,
+};
+
+/// Tuple of format string and formatted size for time code A.
+///
+/// Format: YYYY-MM-DDThh:mm:ss.ddd
+///
+/// Three digits are used for the decimal fraction
+pub const FMT_STR_CODE_A_WITH_SIZE: (&str, usize) = ("%FT%T%.3f", 23);
+/// Tuple of format string and formatted size for time code A.
+///
+///  Format: YYYY-MM-DDThh:mm:ss.dddZ
+///
+/// Three digits are used for the decimal fraction and a terminator is added at the end.
+pub const FMT_STR_CODE_A_TERMINATED_WITH_SIZE: (&str, usize) = ("%FT%T%.3fZ", 24);
+
+/// Tuple of format string and formatted size for time code A.
+///
+/// Format: YYYY-DDDThh:mm:ss.ddd
+///
+/// Three digits are used for the decimal fraction
+pub const FMT_STR_CODE_B_WITH_SIZE: (&str, usize) = ("%Y-%jT%T%.3f", 21);
+/// Tuple of format string and formatted size for time code A.
+///
+/// Format: YYYY-DDDThh:mm:ss.dddZ
+///
+/// Three digits are used for the decimal fraction and a terminator is added at the end.
+pub const FMT_STR_CODE_B_TERMINATED_WITH_SIZE: (&str, usize) = ("%Y-%jT%T%.3fZ", 22);
+
+/// Generates a time code formatter using the [FMT_STR_CODE_A_WITH_SIZE] format.
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+pub fn generate_time_code_a(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
+    date.format(FMT_STR_CODE_A_WITH_SIZE.0)
+}
+
+/// Generates a time code formatter using the [FMT_STR_CODE_A_TERMINATED_WITH_SIZE] format.
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+pub fn generate_time_code_a_terminated(
+    date: &DateTime<Utc>,
+) -> DelayedFormat<StrftimeItems<'static>> {
+    date.format(FMT_STR_CODE_A_TERMINATED_WITH_SIZE.0)
+}
+
+/// Generates a time code formatter using the [FMT_STR_CODE_B_WITH_SIZE] format.
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+pub fn generate_time_code_b(date: &DateTime<Utc>) -> DelayedFormat<StrftimeItems<'static>> {
+    date.format(FMT_STR_CODE_B_WITH_SIZE.0)
+}
+
+/// Generates a time code formatter using the [FMT_STR_CODE_B_TERMINATED_WITH_SIZE] format.
+#[cfg(feature = "alloc")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
+pub fn generate_time_code_b_terminated(
+    date: &DateTime<Utc>,
+) -> DelayedFormat<StrftimeItems<'static>> {
+    date.format(FMT_STR_CODE_B_TERMINATED_WITH_SIZE.0)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::Utc;
+    use std::format;
+
+    #[test]
+    fn test_ascii_timestamp_a_unterminated() {
+        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() {
+        let date = Utc::now();
+        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]
+    fn test_ascii_timestamp_b_unterminated() {
+        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() {
+        let date = Utc::now();
+        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);
+    }
+}

src/time/mod.rs

@@ -0,0 +1,547 @@
+//! 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};
+use core::cmp::Ordering;
+use core::fmt::{Display, Formatter};
+use core::ops::{Add, AddAssign};
+use core::time::Duration;
+use core::u8;
+
+#[allow(unused_imports)]
+#[cfg(not(feature = "std"))]
+use num_traits::float::FloatCore;
+
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+#[cfg(feature = "std")]
+use std::time::{SystemTime, SystemTimeError};
+#[cfg(feature = "std")]
+pub use std_mod::*;
+
+pub mod ascii;
+pub mod cds;
+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;
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum CcsdsTimeCodes {
+    CucCcsdsEpoch = 0b001,
+    CucAgencyEpoch = 0b010,
+    Cds = 0b100,
+    Ccs = 0b101,
+    AgencyDefined = 0b110,
+}
+
+impl TryFrom<u8> for CcsdsTimeCodes {
+    type Error = ();
+
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        match value {
+            x if x == CcsdsTimeCodes::CucCcsdsEpoch as u8 => Ok(CcsdsTimeCodes::CucCcsdsEpoch),
+            x if x == CcsdsTimeCodes::CucAgencyEpoch as u8 => Ok(CcsdsTimeCodes::CucAgencyEpoch),
+            x if x == CcsdsTimeCodes::Cds as u8 => Ok(CcsdsTimeCodes::Cds),
+            x if x == CcsdsTimeCodes::Ccs as u8 => Ok(CcsdsTimeCodes::Ccs),
+            x if x == CcsdsTimeCodes::AgencyDefined as u8 => Ok(CcsdsTimeCodes::AgencyDefined),
+            _ => Err(()),
+        }
+    }
+}
+
+/// 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> {
+    let raw_bits = (pfield >> 4) & 0b111;
+    CcsdsTimeCodes::try_from(raw_bits).map_err(|_| raw_bits)
+}
+
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[non_exhaustive]
+pub enum TimestampError {
+    InvalidTimeCode { expected: CcsdsTimeCodes, found: u8 },
+    ByteConversion(ByteConversionError),
+    Cds(cds::CdsError),
+    Cuc(cuc::CucError),
+    DateBeforeCcsdsEpoch(DateTime<Utc>),
+    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, "byte conversion error {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;
+    use thiserror::Error;
+
+    #[derive(Debug, Clone, Error)]
+    pub enum StdTimestampError {
+        #[error("system time error: {0}")]
+        SystemTime(#[from] SystemTimeError),
+        #[error("timestamp error: {0}")]
+        Timestamp(#[from] TimestampError),
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+pub fn seconds_since_epoch() -> f64 {
+    SystemTime::now()
+        .duration_since(SystemTime::UNIX_EPOCH)
+        .expect("System time generation failed")
+        .as_secs_f64()
+}
+
+/// Convert UNIX days to CCSDS days
+///
+///  - CCSDS epoch: 1958-01-01T00:00:00+00:00
+///  - UNIX Epoch: 1970-01-01T00:00:00+00:00
+pub const fn unix_to_ccsds_days(unix_days: i64) -> i64 {
+    unix_days - DAYS_CCSDS_TO_UNIX as i64
+}
+
+/// Convert CCSDS days to UNIX days
+///
+///  - CCSDS epoch: 1958-01-01T00:00:00+00:00
+///  - UNIX Epoch: 1970-01-01T00:00:00+00:00
+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.
+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)
+}
+
+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())
+}
+
+pub fn ms_of_day(seconds_since_epoch: f64) -> u32 {
+    let fraction_ms = seconds_since_epoch - seconds_since_epoch.floor();
+    let ms_of_day: u32 = (((seconds_since_epoch.floor() as u32 % SECONDS_PER_DAY) * 1000) as f64
+        + fraction_ms)
+        .floor() as u32;
+    ms_of_day
+}
+
+pub trait TimeWriter {
+    /// Generic function to convert write a timestamp into a raw buffer.
+    /// Returns the number of written bytes on success.
+    fn write_to_bytes(&self, bytes: &mut [u8]) -> Result<usize, TimestampError>;
+}
+
+pub trait TimeReader {
+    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
+/// practical because they are a very common and simple exchange format for time information.
+pub trait CcsdsTimeProvider {
+    fn len_as_bytes(&self) -> usize;
+
+    /// Returns the pfield of the time provider. The pfield can have one or two bytes depending
+    /// on the extension bit (first bit). The time provider should returns a tuple where the first
+    /// 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 unix_seconds(&self) -> i64;
+    fn subsecond_millis(&self) -> Option<u16>;
+    fn unix_stamp(&self) -> UnixTimestamp {
+        if self.subsecond_millis().is_none() {
+            return UnixTimestamp::new_only_seconds(self.unix_seconds());
+        }
+        UnixTimestamp::const_new(self.unix_seconds(), self.subsecond_millis().unwrap())
+    }
+
+    fn date_time(&self) -> Option<DateTime<Utc>>;
+}
+
+/// UNIX timestamp: Elapsed seconds since 1970-01-01T00:00:00+00:00.
+///
+/// Also can optionally include subsecond millisecond for greater accuracy. Please note that a
+/// subsecond millisecond value of 0 gets converted to [None].
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct UnixTimestamp {
+    pub unix_seconds: i64,
+    subsecond_millis: Option<u16>,
+}
+
+impl UnixTimestamp {
+    /// Returns none if the subsecond millisecond value is larger than 999. 0 is converted to
+    /// a [None] value.
+    pub fn new(unix_seconds: i64, subsec_millis: u16) -> Option<Self> {
+        if subsec_millis > 999 {
+            return None;
+        }
+        Some(Self::const_new(unix_seconds, subsec_millis))
+    }
+
+    /// Like [Self::new] but const. Panics if the subsecond value is larger than 999.
+    pub const fn const_new(unix_seconds: i64, subsec_millis: u16) -> Self {
+        if subsec_millis > 999 {
+            panic!("subsec milliseconds exceeds 999");
+        }
+        let subsecond_millis = if subsec_millis == 0 {
+            None
+        } else {
+            Some(subsec_millis)
+        };
+        Self {
+            unix_seconds,
+            subsecond_millis,
+        }
+    }
+
+    pub fn new_only_seconds(unix_seconds: i64) -> Self {
+        Self {
+            unix_seconds,
+            subsecond_millis: None,
+        }
+    }
+
+    pub fn subsecond_millis(&self) -> Option<u16> {
+        self.subsecond_millis
+    }
+
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    pub fn from_now() -> Result<Self, SystemTimeError> {
+        let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
+        let epoch = now.as_secs();
+        Ok(Self::const_new(epoch as i64, now.subsec_millis() as u16))
+    }
+
+    #[inline]
+    pub fn unix_seconds_f64(&self) -> f64 {
+        let mut secs = self.unix_seconds as f64;
+        if let Some(subsec_millis) = self.subsecond_millis {
+            secs += subsec_millis as f64 / 1000.0;
+        }
+        secs
+    }
+
+    pub fn as_date_time(&self) -> LocalResult<DateTime<Utc>> {
+        Utc.timestamp_opt(
+            self.unix_seconds,
+            self.subsecond_millis.unwrap_or(0) as u32 * 10_u32.pow(6),
+        )
+    }
+}
+
+impl From<DateTime<Utc>> for UnixTimestamp {
+    fn from(value: DateTime<Utc>) -> Self {
+        Self::const_new(value.timestamp(), value.timestamp_subsec_millis() as u16)
+    }
+}
+
+impl PartialOrd for UnixTimestamp {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self == other {
+            return Some(Ordering::Equal);
+        }
+        match self.unix_seconds.cmp(&other.unix_seconds) {
+            Ordering::Less => return Some(Ordering::Less),
+            Ordering::Greater => return Some(Ordering::Greater),
+            _ => (),
+        }
+
+        match self
+            .subsecond_millis()
+            .unwrap_or(0)
+            .cmp(&other.subsecond_millis().unwrap_or(0))
+        {
+            Ordering::Less => {
+                return if self.unix_seconds < 0 {
+                    Some(Ordering::Greater)
+                } else {
+                    Some(Ordering::Less)
+                }
+            }
+            Ordering::Greater => {
+                return if self.unix_seconds < 0 {
+                    Some(Ordering::Less)
+                } else {
+                    Some(Ordering::Greater)
+                }
+            }
+            Ordering::Equal => (),
+        }
+        Some(Ordering::Equal)
+    }
+}
+
+impl Ord for UnixTimestamp {
+    fn cmp(&self, other: &Self) -> Ordering {
+        PartialOrd::partial_cmp(self, other).unwrap()
+    }
+}
+
+fn get_new_stamp_after_addition(
+    current_stamp: &UnixTimestamp,
+    duration: Duration,
+) -> UnixTimestamp {
+    let mut new_subsec_millis =
+        current_stamp.subsecond_millis().unwrap_or(0) + duration.subsec_millis() as u16;
+    let mut new_unix_seconds = current_stamp.unix_seconds;
+    let mut increment_seconds = |value: u32| {
+        if new_unix_seconds < 0 {
+            new_unix_seconds = new_unix_seconds
+                .checked_sub(value.into())
+                .expect("new unix seconds would exceed i64::MIN");
+        } else {
+            new_unix_seconds = new_unix_seconds
+                .checked_add(value.into())
+                .expect("new unix seconds would exceed i64::MAX");
+        }
+    };
+    if new_subsec_millis >= 1000 {
+        new_subsec_millis -= 1000;
+        increment_seconds(1);
+    }
+    increment_seconds(
+        duration
+            .as_secs()
+            .try_into()
+            .expect("duration seconds exceeds u32::MAX"),
+    );
+    UnixTimestamp::const_new(new_unix_seconds, new_subsec_millis)
+}
+
+/// Please note that this operation will panic on the following conditions:
+///
+/// - 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 {
+    fn add_assign(&mut self, duration: Duration) {
+        *self = get_new_stamp_after_addition(self, duration);
+    }
+}
+
+/// Please note that this operation will panic for the following conditions:
+///
+/// - 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 {
+    type Output = Self;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        get_new_stamp_after_addition(&self, duration)
+    }
+}
+
+impl Add<Duration> for &UnixTimestamp {
+    type Output = UnixTimestamp;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        get_new_stamp_after_addition(self, duration)
+    }
+}
+
+#[cfg(all(test, feature = "std"))]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_days_conversion() {
+        assert_eq!(unix_to_ccsds_days(DAYS_CCSDS_TO_UNIX.into()), 0);
+        assert_eq!(ccsds_to_unix_days(0), DAYS_CCSDS_TO_UNIX.into());
+    }
+
+    #[test]
+    fn test_get_current_time() {
+        let sec_floats = seconds_since_epoch();
+        assert!(sec_floats > 0.0);
+    }
+
+    #[test]
+    fn test_ccsds_epoch() {
+        let now = SystemTime::now()
+            .duration_since(SystemTime::UNIX_EPOCH)
+            .unwrap();
+        let unix_epoch = now.as_secs();
+        let ccsds_epoch = unix_epoch_to_ccsds_epoch(now.as_secs() as i64) as u64;
+        assert!(ccsds_epoch > unix_epoch);
+        assert_eq!((ccsds_epoch - unix_epoch) % SECONDS_PER_DAY as u64, 0);
+        let days_diff = (ccsds_epoch - unix_epoch) / SECONDS_PER_DAY as u64;
+        assert_eq!(days_diff, -DAYS_CCSDS_TO_UNIX as u64);
+    }
+
+    #[test]
+    fn basic_unix_stamp_test() {
+        let stamp = UnixTimestamp::new_only_seconds(-200);
+        assert_eq!(stamp.unix_seconds, -200);
+        assert!(stamp.subsecond_millis().is_none());
+        let stamp = UnixTimestamp::new_only_seconds(250);
+        assert_eq!(stamp.unix_seconds, 250);
+        assert!(stamp.subsecond_millis().is_none());
+    }
+
+    #[test]
+    fn basic_float_unix_stamp_test() {
+        let stamp = UnixTimestamp::new(500, 600).unwrap();
+        assert!(stamp.subsecond_millis.is_some());
+        assert_eq!(stamp.unix_seconds, 500);
+        let subsec_millis = stamp.subsecond_millis().unwrap();
+        assert_eq!(subsec_millis, 600);
+        assert!((500.6 - stamp.unix_seconds_f64()).abs() < 0.0001);
+    }
+
+    #[test]
+    fn test_ord_larger() {
+        let stamp0 = UnixTimestamp::new_only_seconds(5);
+        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        assert!(stamp1 > stamp0);
+        assert!(stamp2 > stamp0);
+        assert!(stamp2 > stamp1);
+    }
+
+    #[test]
+    fn test_ord_smaller() {
+        let stamp0 = UnixTimestamp::new_only_seconds(5);
+        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        assert!(stamp0 < stamp1);
+        assert!(stamp0 < stamp2);
+        assert!(stamp1 < stamp2);
+    }
+
+    #[test]
+    fn test_ord_larger_neg_numbers() {
+        let stamp0 = UnixTimestamp::new_only_seconds(-5);
+        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        assert!(stamp0 > stamp1);
+        assert!(stamp0 > stamp2);
+        assert!(stamp1 > stamp2);
+        assert!(stamp1 >= stamp2);
+        assert!(stamp0 >= stamp1);
+    }
+
+    #[test]
+    fn test_ord_smaller_neg_numbers() {
+        let stamp0 = UnixTimestamp::new_only_seconds(-5);
+        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        assert!(stamp2 < stamp1);
+        assert!(stamp2 < stamp0);
+        assert!(stamp1 < stamp0);
+        assert!(stamp1 <= stamp0);
+        assert!(stamp2 <= stamp1);
+    }
+
+    #[test]
+    fn test_eq() {
+        let stamp0 = UnixTimestamp::new(5, 0).unwrap();
+        let stamp1 = UnixTimestamp::new_only_seconds(5);
+        assert_eq!(stamp0, stamp1);
+        assert!(stamp0 <= stamp1);
+        assert!(stamp0 >= stamp1);
+        assert!(!(stamp0 < stamp1));
+        assert!(!(stamp0 > stamp1));
+    }
+
+    #[test]
+    fn test_addition() {
+        let mut stamp0 = UnixTimestamp::new_only_seconds(1);
+        stamp0 += Duration::from_secs(5);
+        assert_eq!(stamp0.unix_seconds, 6);
+        assert!(stamp0.subsecond_millis().is_none());
+        let stamp1 = stamp0 + Duration::from_millis(500);
+        assert_eq!(stamp1.unix_seconds, 6);
+        assert!(stamp1.subsecond_millis().is_some());
+        assert_eq!(stamp1.subsecond_millis().unwrap(), 500);
+    }
+
+    #[test]
+    fn test_addition_on_ref() {
+        let stamp0 = &UnixTimestamp::new(20, 500).unwrap();
+        let stamp1 = stamp0 + Duration::from_millis(2500);
+        assert_eq!(stamp1.unix_seconds, 23);
+        assert!(stamp1.subsecond_millis().is_none());
+    }
+
+    #[test]
+    fn test_addition_spillover() {
+        let mut stamp0 = UnixTimestamp::new(1, 900).unwrap();
+        stamp0 += Duration::from_millis(100);
+        assert_eq!(stamp0.unix_seconds, 2);
+        assert!(stamp0.subsecond_millis().is_none());
+        stamp0 += Duration::from_millis(1100);
+        assert_eq!(stamp0.unix_seconds, 3);
+        assert_eq!(stamp0.subsecond_millis().unwrap(), 100);
+    }
+}

src/tm.rs

@@ -1,669 +0,0 @@
-//! This module contains all components required to create a ECSS PUS C telemetry packets according
-//! to [ECSS-E-ST-70-41C](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
-use crate::ecss::{
-    ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
-    verify_crc16_from_raw, CrcType, PusError, PusPacket, PusVersion, CRC_CCITT_FALSE,
-};
-use crate::{
-    ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SizeMissmatch, SpHeader,
-    CCSDS_HEADER_LEN,
-};
-use core::mem::size_of;
-use serde::{Deserialize, Serialize};
-use zerocopy::AsBytes;
-
-#[cfg(feature = "alloc")]
-use alloc::vec::Vec;
-use delegate::delegate;
-
-/// Length without timestamp
-pub const PUC_TM_MIN_SEC_HEADER_LEN: usize = 7;
-pub const PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA: usize =
-    CCSDS_HEADER_LEN + PUC_TM_MIN_SEC_HEADER_LEN + size_of::<CrcType>();
-
-pub trait PusTmSecondaryHeaderT {
-    fn pus_version(&self) -> PusVersion;
-    fn sc_time_ref_status(&self) -> u8;
-    fn service(&self) -> u8;
-    fn subservice(&self) -> u8;
-    fn msg_counter(&self) -> u16;
-    fn dest_id(&self) -> u16;
-}
-
-pub mod zc {
-    use crate::ecss::{PusError, PusVersion};
-    use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
-
-    #[derive(FromBytes, AsBytes, Unaligned)]
-    #[repr(C)]
-    pub struct PusTmSecHeaderWithoutTimestamp {
-        pus_version_and_sc_time_ref_status: u8,
-        service: u8,
-        subservice: u8,
-        msg_counter: U16<NetworkEndian>,
-        dest_id: U16<NetworkEndian>,
-    }
-
-    pub struct PusTmSecHeader<'slice> {
-        pub(crate) zc_header: PusTmSecHeaderWithoutTimestamp,
-        pub(crate) timestamp: &'slice [u8],
-    }
-
-    impl TryFrom<crate::tm::PusTmSecondaryHeader<'_>> for PusTmSecHeaderWithoutTimestamp {
-        type Error = PusError;
-        fn try_from(header: crate::tm::PusTmSecondaryHeader) -> Result<Self, Self::Error> {
-            if header.pus_version != PusVersion::PusC {
-                return Err(PusError::VersionNotSupported(header.pus_version));
-            }
-            Ok(PusTmSecHeaderWithoutTimestamp {
-                pus_version_and_sc_time_ref_status: ((header.pus_version as u8) << 4)
-                    | header.sc_time_ref_status,
-                service: header.service,
-                subservice: header.subservice,
-                msg_counter: U16::from(header.msg_counter),
-                dest_id: U16::from(header.dest_id),
-            })
-        }
-    }
-
-    impl PusTmSecHeaderWithoutTimestamp {
-        pub fn write_to_bytes(&self, slice: &mut [u8]) -> Option<()> {
-            self.write_to(slice)
-        }
-
-        pub fn from_bytes(slice: &[u8]) -> Option<Self> {
-            Self::read_from(slice)
-        }
-    }
-
-    impl super::PusTmSecondaryHeaderT for PusTmSecHeaderWithoutTimestamp {
-        fn pus_version(&self) -> PusVersion {
-            PusVersion::try_from(self.pus_version_and_sc_time_ref_status >> 4 & 0b1111)
-                .unwrap_or(PusVersion::Invalid)
-        }
-
-        fn sc_time_ref_status(&self) -> u8 {
-            self.pus_version_and_sc_time_ref_status & 0b1111
-        }
-
-        fn service(&self) -> u8 {
-            self.service
-        }
-
-        fn subservice(&self) -> u8 {
-            self.subservice
-        }
-
-        fn msg_counter(&self) -> u16 {
-            self.msg_counter.get()
-        }
-
-        fn dest_id(&self) -> u16 {
-            self.dest_id.get()
-        }
-    }
-}
-
-#[derive(PartialEq, Eq, Serialize, Deserialize, Copy, Clone, Debug)]
-pub struct PusTmSecondaryHeader<'slice> {
-    pus_version: PusVersion,
-    pub sc_time_ref_status: u8,
-    pub service: u8,
-    pub subservice: u8,
-    pub msg_counter: u16,
-    pub dest_id: u16,
-    pub time_stamp: &'slice [u8],
-}
-
-impl<'slice> PusTmSecondaryHeader<'slice> {
-    pub fn new_simple(service: u8, subservice: u8, time_stamp: &'slice [u8]) -> Self {
-        PusTmSecondaryHeader {
-            pus_version: PusVersion::PusC,
-            sc_time_ref_status: 0,
-            service,
-            subservice,
-            msg_counter: 0,
-            dest_id: 0,
-            time_stamp,
-        }
-    }
-
-    pub fn new(
-        service: u8,
-        subservice: u8,
-        msg_counter: u16,
-        dest_id: u16,
-        time_stamp: &'slice [u8],
-    ) -> Self {
-        PusTmSecondaryHeader {
-            pus_version: PusVersion::PusC,
-            sc_time_ref_status: 0,
-            service,
-            subservice,
-            msg_counter,
-            dest_id,
-            time_stamp,
-        }
-    }
-}
-
-impl PusTmSecondaryHeaderT for PusTmSecondaryHeader<'_> {
-    fn pus_version(&self) -> PusVersion {
-        self.pus_version
-    }
-
-    fn sc_time_ref_status(&self) -> u8 {
-        self.sc_time_ref_status
-    }
-
-    fn service(&self) -> u8 {
-        self.service
-    }
-
-    fn subservice(&self) -> u8 {
-        self.subservice
-    }
-
-    fn msg_counter(&self) -> u16 {
-        self.msg_counter
-    }
-
-    fn dest_id(&self) -> u16 {
-        self.dest_id
-    }
-}
-
-impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice> {
-    type Error = ();
-
-    fn try_from(sec_header: zc::PusTmSecHeader<'slice>) -> Result<Self, Self::Error> {
-        Ok(PusTmSecondaryHeader {
-            pus_version: sec_header.zc_header.pus_version(),
-            sc_time_ref_status: sec_header.zc_header.sc_time_ref_status(),
-            service: sec_header.zc_header.service(),
-            subservice: sec_header.zc_header.subservice(),
-            msg_counter: sec_header.zc_header.msg_counter(),
-            dest_id: sec_header.zc_header.dest_id(),
-            time_stamp: sec_header.timestamp,
-        })
-    }
-}
-
-/// This class models a PUS telemetry and which can also be used. It is the primary data
-/// structure to generate the raw byte representation of PUS telemetry or to
-/// deserialize from one from raw bytes.
-///
-/// This class also derives the [serde::Serialize] and [serde::Deserialize] trait which allows
-/// to send around TM packets in a raw byte format using a serde provider like
-/// [postcard](https://docs.rs/postcard/latest/postcard/).
-///
-/// There is no spare bytes support yet.
-#[derive(PartialEq, Eq, Serialize, Deserialize, Debug, Copy, Clone)]
-pub struct PusTm<'slice> {
-    pub sp_header: SpHeader,
-    pub sec_header: PusTmSecondaryHeader<'slice>,
-    /// If this is set to false, a manual call to [PusTm::calc_own_crc16] or
-    /// [PusTm::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
-    pub calc_crc_on_serialization: bool,
-    #[serde(skip)]
-    raw_data: Option<&'slice [u8]>,
-    source_data: Option<&'slice [u8]>,
-    crc16: Option<u16>,
-}
-
-impl<'slice> PusTm<'slice> {
-    /// Generates a new struct instance.
-    ///
-    /// # Arguments
-    ///
-    /// * `sp_header` - Space packet header information. The correct packet type will be set
-    ///     automatically
-    /// * `sec_header` - Information contained in the secondary header, including the service
-    ///     and subservice type
-    /// * `app_data` - Custom application data
-    /// * `set_ccsds_len` - Can be used to automatically update the CCSDS space packet data length
-    ///     field. If this is not set to true, [PusTm::update_ccsds_data_len] can be called to set
-    ///     the correct value to this field manually
-    pub fn new(
-        sp_header: &mut SpHeader,
-        sec_header: PusTmSecondaryHeader<'slice>,
-        source_data: Option<&'slice [u8]>,
-        set_ccsds_len: bool,
-    ) -> Self {
-        sp_header.set_packet_type(PacketType::Tm);
-        sp_header.set_sec_header_flag();
-        let mut pus_tm = PusTm {
-            sp_header: *sp_header,
-            raw_data: None,
-            source_data,
-            sec_header,
-            calc_crc_on_serialization: true,
-            crc16: None,
-        };
-        if set_ccsds_len {
-            pus_tm.update_ccsds_data_len();
-        }
-        pus_tm
-    }
-
-    pub fn len_packed(&self) -> usize {
-        let mut length = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA;
-        length += self.sec_header.time_stamp.len();
-        if let Some(src_data) = self.source_data {
-            length += src_data.len();
-        }
-        length
-    }
-
-    pub fn time_stamp(&self) -> &'slice [u8] {
-        self.sec_header.time_stamp
-    }
-
-    pub fn source_data(&self) -> Option<&'slice [u8]> {
-        self.source_data
-    }
-
-    pub fn set_dest_id(&mut self, dest_id: u16) {
-        self.sec_header.dest_id = dest_id;
-    }
-
-    pub fn set_msg_counter(&mut self, msg_counter: u16) {
-        self.sec_header.msg_counter = msg_counter
-    }
-
-    pub fn set_sc_time_ref_status(&mut self, sc_time_ref_status: u8) {
-        self.sec_header.sc_time_ref_status = sc_time_ref_status & 0b1111;
-    }
-
-    sp_header_impls!();
-
-    /// This is called automatically if the `set_ccsds_len` argument in the [PusTm::new] call was
-    /// used.
-    /// If this was not done or the time stamp or source data is set or changed after construction,
-    /// this function needs to be called to ensure that the data length field of the CCSDS header
-    /// is set correctly
-    pub fn update_ccsds_data_len(&mut self) {
-        self.sp_header.data_len =
-            self.len_packed() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
-    }
-
-    /// This function should be called before the TM packet is serialized if
-    /// [PusTm.calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
-    pub fn calc_own_crc16(&mut self) {
-        let mut digest = CRC_CCITT_FALSE.digest();
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        digest.update(sph_zc.as_bytes());
-        let pus_tc_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        digest.update(pus_tc_header.as_bytes());
-        digest.update(self.sec_header.time_stamp);
-        if let Some(src_data) = self.source_data {
-            digest.update(src_data);
-        }
-        self.crc16 = Some(digest.finalize())
-    }
-
-    /// This helper function calls both [PusTm.update_ccsds_data_len] and [PusTm.calc_own_crc16]
-    pub fn update_packet_fields(&mut self) {
-        self.update_ccsds_data_len();
-        self.calc_own_crc16();
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = 0;
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        let total_size = self.len_packed();
-        if total_size > slice.len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: slice.len(),
-                expected: total_size,
-            })
-            .into());
-        }
-        sph_zc
-            .to_bytes(&mut slice[curr_idx..curr_idx + CCSDS_HEADER_LEN])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header_len = size_of::<zc::PusTmSecHeaderWithoutTimestamp>();
-        let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        sec_header
-            .write_to_bytes(&mut slice[curr_idx..curr_idx + sec_header_len])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-        curr_idx += sec_header_len;
-        let timestamp_len = self.sec_header.time_stamp.len();
-        slice[curr_idx..curr_idx + timestamp_len].copy_from_slice(self.sec_header.time_stamp);
-        curr_idx += timestamp_len;
-        if let Some(src_data) = self.source_data {
-            slice[curr_idx..curr_idx + src_data.len()].copy_from_slice(src_data);
-            curr_idx += src_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            0,
-            curr_idx,
-            slice,
-        )?;
-        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
-    /// Append the raw PUS byte representation to a provided [alloc::vec::Vec]
-    #[cfg(feature = "alloc")]
-    #[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
-    pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PusError> {
-        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        let mut appended_len =
-            PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA + self.sec_header.time_stamp.len();
-        if let Some(src_data) = self.source_data {
-            appended_len += src_data.len();
-        };
-        let start_idx = vec.len();
-        let mut ser_len = 0;
-        vec.extend_from_slice(sph_zc.as_bytes());
-        ser_len += sph_zc.as_bytes().len();
-        // The PUS version is hardcoded to PUS C
-        let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        vec.extend_from_slice(sec_header.as_bytes());
-        ser_len += sec_header.as_bytes().len();
-        vec.extend_from_slice(self.sec_header.time_stamp);
-        ser_len += self.sec_header.time_stamp.len();
-        if let Some(src_data) = self.source_data {
-            vec.extend_from_slice(src_data);
-            ser_len += src_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            start_idx,
-            ser_len,
-            &vec[start_idx..start_idx + ser_len],
-        )?;
-        vec.extend_from_slice(crc16.to_be_bytes().as_slice());
-        Ok(appended_len)
-    }
-
-    /// Create a [PusTm] instance from a raw slice. On success, it returns a tuple containing
-    /// the instance and the found byte length of the packet. The timestamp length needs to be
-    /// known beforehand.
-    pub fn from_bytes(
-        slice: &'slice [u8],
-        timestamp_len: usize,
-    ) -> Result<(Self, usize), PusError> {
-        let raw_data_len = slice.len();
-        if raw_data_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
-            return Err(PusError::RawDataTooShort(raw_data_len));
-        }
-        let mut current_idx = 0;
-        let sph =
-            crate::zc::SpHeader::from_bytes(&slice[current_idx..current_idx + CCSDS_HEADER_LEN])
-                .ok_or(ByteConversionError::ZeroCopyFromError)?;
-        current_idx += 6;
-        let total_len = sph.total_len();
-        if raw_data_len < total_len || total_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
-            return Err(PusError::RawDataTooShort(raw_data_len));
-        }
-        let sec_header_zc = zc::PusTmSecHeaderWithoutTimestamp::from_bytes(
-            &slice[current_idx..current_idx + PUC_TM_MIN_SEC_HEADER_LEN],
-        )
-        .ok_or(ByteConversionError::ZeroCopyFromError)?;
-        current_idx += PUC_TM_MIN_SEC_HEADER_LEN;
-        let zc_sec_header_wrapper = zc::PusTmSecHeader {
-            zc_header: sec_header_zc,
-            timestamp: &slice[current_idx..current_idx + timestamp_len],
-        };
-        current_idx += timestamp_len;
-        let raw_data = &slice[0..total_len];
-        let pus_tm = PusTm {
-            sp_header: SpHeader::from(sph),
-            sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper).unwrap(),
-            raw_data: Some(&slice[0..total_len]),
-            source_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
-            calc_crc_on_serialization: false,
-            crc16: Some(crc_from_raw_data(raw_data)?),
-        };
-        verify_crc16_from_raw(raw_data, pus_tm.crc16.expect("CRC16 invalid"))?;
-        Ok((pus_tm, total_len))
-    }
-}
-
-//noinspection RsTraitImplementation
-impl CcsdsPacket for PusTm<'_> {
-    ccsds_impl!();
-}
-
-//noinspection RsTraitImplementation
-impl PusPacket for PusTm<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-    });
-
-    fn user_data(&self) -> Option<&[u8]> {
-        self.source_data
-    }
-
-    fn crc16(&self) -> Option<u16> {
-        self.crc16
-    }
-}
-
-//noinspection RsTraitImplementation
-impl PusTmSecondaryHeaderT for PusTm<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-        fn dest_id(&self) -> u16;
-        fn msg_counter(&self) -> u16;
-        fn sc_time_ref_status(&self) -> u8;
-    });
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::ecss::PusVersion::PusC;
-    use crate::SpHeader;
-
-    fn base_ping_reply_full_ctor(time_stamp: &[u8]) -> PusTm {
-        let mut sph = SpHeader::tm(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, &time_stamp);
-        PusTm::new(&mut sph, tc_header, None, true)
-    }
-
-    fn base_hk_reply<'a>(time_stamp: &'a [u8], src_data: &'a [u8]) -> PusTm<'a> {
-        let mut sph = SpHeader::tm(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, &time_stamp);
-        PusTm::new(&mut sph, tc_header, Some(src_data), true)
-    }
-
-    fn dummy_time_stamp() -> &'static [u8] {
-        return &[0, 1, 2, 3, 4, 5, 6];
-    }
-
-    #[test]
-    fn test_basic() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        verify_ping_reply(&pus_tm, false, 22, dummy_time_stamp());
-    }
-
-    #[test]
-    fn test_serialization_no_source_data() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        verify_raw_ping_reply(&buf);
-    }
-
-    #[test]
-    fn test_serialization_with_source_data() {
-        let src_data = [1, 2, 3];
-        let hk_reply = base_hk_reply(dummy_time_stamp(), &src_data);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = hk_reply
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 25);
-        assert_eq!(buf[20], 1);
-        assert_eq!(buf[21], 2);
-        assert_eq!(buf[22], 3);
-    }
-
-    #[test]
-    fn test_setters() {
-        let time_stamp = dummy_time_stamp();
-        let mut pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        pus_tm.set_sc_time_ref_status(0b1010);
-        pus_tm.set_dest_id(0x7fff);
-        pus_tm.set_msg_counter(0x1f1f);
-        assert_eq!(pus_tm.sc_time_ref_status(), 0b1010);
-        assert_eq!(pus_tm.dest_id(), 0x7fff);
-        assert_eq!(pus_tm.msg_counter(), 0x1f1f);
-        assert!(pus_tm.set_apid(0x7ff));
-        assert_eq!(pus_tm.apid(), 0x7ff);
-    }
-
-    #[test]
-    fn test_deserialization_no_source_data() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        let (tm_deserialized, size) = PusTm::from_bytes(&buf, 7).expect("Deserialization failed");
-        assert_eq!(ser_len, size);
-        verify_ping_reply(&tm_deserialized, false, 22, dummy_time_stamp());
-    }
-
-    #[test]
-    fn test_manual_field_update() {
-        let mut sph = SpHeader::tm(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, dummy_time_stamp());
-        let mut tm = PusTm::new(&mut sph, tc_header, None, false);
-        tm.calc_crc_on_serialization = false;
-        assert_eq!(tm.data_len(), 0x00);
-        let mut buf: [u8; 32] = [0; 32];
-        let res = tm.write_to_bytes(&mut buf);
-        assert!(res.is_err());
-        assert!(matches!(res.unwrap_err(), PusError::CrcCalculationMissing));
-        tm.update_ccsds_data_len();
-        assert_eq!(tm.data_len(), 15);
-        tm.calc_own_crc16();
-        let res = tm.write_to_bytes(&mut buf);
-        assert!(res.is_ok());
-        tm.sp_header.data_len = 0;
-        tm.update_packet_fields();
-        assert_eq!(tm.data_len(), 15);
-    }
-
-    #[test]
-    fn test_target_buf_too_small() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        let mut buf: [u8; 16] = [0; 16];
-        let res = pus_tm.write_to_bytes(&mut buf);
-        assert!(res.is_err());
-        let error = res.unwrap_err();
-        assert!(matches!(error, PusError::ByteConversionError { .. }));
-        match error {
-            PusError::ByteConversionError(err) => match err {
-                ByteConversionError::ToSliceTooSmall(size_missmatch) => {
-                    assert_eq!(size_missmatch.expected, 22);
-                    assert_eq!(size_missmatch.found, 16);
-                }
-                _ => panic!("Invalid PUS error {:?}", err),
-            },
-            _ => {
-                panic!("Invalid error {:?}", error);
-            }
-        }
-    }
-
-    #[test]
-    #[cfg(feature = "alloc")]
-    fn test_append_to_vec() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        let mut vec = Vec::new();
-        let res = pus_tm.append_to_vec(&mut vec);
-        assert!(res.is_ok());
-        assert_eq!(res.unwrap(), 22);
-        verify_raw_ping_reply(vec.as_slice());
-    }
-
-    #[test]
-    #[cfg(feature = "alloc")]
-    fn test_append_to_vec_with_src_data() {
-        let src_data = [1, 2, 3];
-        let hk_reply = base_hk_reply(dummy_time_stamp(), &src_data);
-        let mut vec = Vec::new();
-        vec.push(4);
-        let res = hk_reply.append_to_vec(&mut vec);
-        assert!(res.is_ok());
-        assert_eq!(res.unwrap(), 25);
-        assert_eq!(vec.len(), 26);
-    }
-
-    fn verify_raw_ping_reply(buf: &[u8]) {
-        // Secondary header is set -> 0b0000_1001 , APID occupies last bit of first byte
-        assert_eq!(buf[0], 0x09);
-        // Rest of APID 0x123
-        assert_eq!(buf[1], 0x23);
-        // Unsegmented is the default, and first byte of 0x234 occupies this byte as well
-        assert_eq!(buf[2], 0xc2);
-        assert_eq!(buf[3], 0x34);
-        assert_eq!(((buf[4] as u16) << 8) | buf[5] as u16, 15);
-        // SC time ref status is 0
-        assert_eq!(buf[6], (PusC as u8) << 4);
-        assert_eq!(buf[7], 17);
-        assert_eq!(buf[8], 2);
-        // MSG counter 0
-        assert_eq!(buf[9], 0x00);
-        assert_eq!(buf[10], 0x00);
-        // Destination ID
-        assert_eq!(buf[11], 0x00);
-        assert_eq!(buf[12], 0x00);
-        // Timestamp
-        assert_eq!(&buf[13..20], dummy_time_stamp());
-        let mut digest = CRC_CCITT_FALSE.digest();
-        digest.update(&buf[0..20]);
-        let crc16 = digest.finalize();
-        assert_eq!(((crc16 >> 8) & 0xff) as u8, buf[20]);
-        assert_eq!((crc16 & 0xff) as u8, buf[21]);
-    }
-
-    fn verify_ping_reply(
-        tm: &PusTm,
-        has_user_data: bool,
-        exp_full_len: usize,
-        exp_time_stamp: &[u8],
-    ) {
-        assert!(tm.is_tm());
-        assert_eq!(PusPacket::service(tm), 17);
-        assert_eq!(PusPacket::subservice(tm), 2);
-        assert!(tm.sec_header_flag());
-        assert_eq!(tm.len_packed(), exp_full_len);
-        assert_eq!(tm.time_stamp(), exp_time_stamp);
-        if has_user_data {
-            assert!(!tm.user_data().is_none());
-        }
-        assert_eq!(PusPacket::pus_version(tm), PusC);
-        assert_eq!(tm.apid(), 0x123);
-        assert_eq!(tm.seq_count(), 0x234);
-        assert_eq!(tm.data_len(), exp_full_len as u16 - 7);
-        assert_eq!(tm.dest_id(), 0x0000);
-        assert_eq!(tm.msg_counter(), 0x0000);
-        assert_eq!(tm.sc_time_ref_status(), 0b0000);
-    }
-}

src/util.rs

@@ -0,0 +1,674 @@
+use crate::ByteConversionError;
+use core::fmt::{Debug, Display, Formatter};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub trait ToBeBytes {
+    type ByteArray: AsRef<[u8]>;
+    /// Length when written to big endian bytes.
+    fn written_len(&self) -> usize;
+    fn to_be_bytes(&self) -> Self::ByteArray;
+}
+
+impl ToBeBytes for () {
+    type ByteArray = [u8; 0];
+
+    fn written_len(&self) -> usize {
+        0
+    }
+
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        []
+    }
+}
+
+impl ToBeBytes for u8 {
+    type ByteArray = [u8; 1];
+
+    fn written_len(&self) -> usize {
+        1
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u8::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u16 {
+    type ByteArray = [u8; 2];
+
+    fn written_len(&self) -> usize {
+        2
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u16::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u32 {
+    type ByteArray = [u8; 4];
+
+    fn written_len(&self) -> usize {
+        4
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u32::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u64 {
+    type ByteArray = [u8; 8];
+
+    fn written_len(&self) -> usize {
+        8
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u64::to_be_bytes(*self)
+    }
+}
+
+pub trait UnsignedEnum {
+    /// Size of the unsigned enumeration in bytes.
+    fn size(&self) -> usize;
+    /// Write the unsigned enumeration to a raw buffer. Returns the written size on success.
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+}
+
+pub trait UnsignedEnumExt: UnsignedEnum + Debug + Copy + Clone + PartialEq + Eq {}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum UnsignedByteFieldError {
+    /// Value is too large for specified width of byte field.
+    ValueTooLargeForWidth {
+        width: usize,
+        value: u64,
+    },
+    /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
+    /// applicable, for example for conversions.
+    InvalidWidth {
+        found: usize,
+        expected: Option<usize>,
+    },
+    ByteConversionError(ByteConversionError),
+}
+
+impl From<ByteConversionError> for UnsignedByteFieldError {
+    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))]
+pub struct UnsignedByteField {
+    width: usize,
+    value: u64,
+}
+
+impl UnsignedByteField {
+    pub const fn new(width: usize, value: u64) -> Self {
+        Self { width, value }
+    }
+
+    pub fn value(&self) -> u64 {
+        self.value
+    }
+
+    pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, UnsignedByteFieldError> {
+        if width > buf.len() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                expected: width,
+                found: buf.len(),
+            }
+            .into());
+        }
+        match width {
+            0 => Ok(Self::new(width, 0)),
+            1 => Ok(Self::new(width, buf[0] as u64)),
+            2 => Ok(Self::new(
+                width,
+                u16::from_be_bytes(buf[0..2].try_into().unwrap()) as u64,
+            )),
+            4 => Ok(Self::new(
+                width,
+                u32::from_be_bytes(buf[0..4].try_into().unwrap()) as u64,
+            )),
+            8 => Ok(Self::new(
+                width,
+                u64::from_be_bytes(buf[0..8].try_into().unwrap()),
+            )),
+            _ => Err(UnsignedByteFieldError::InvalidWidth {
+                found: width,
+                expected: None,
+            }),
+        }
+    }
+}
+
+impl UnsignedEnum for UnsignedByteField {
+    fn size(&self) -> usize {
+        self.width
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.size() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                expected: self.size(),
+                found: buf.len(),
+            });
+        }
+        match self.size() {
+            0 => Ok(0),
+            1 => {
+                let u8 = UnsignedByteFieldU8::try_from(*self).unwrap();
+                u8.write_to_be_bytes(buf)
+            }
+            2 => {
+                let u16 = UnsignedByteFieldU16::try_from(*self).unwrap();
+                u16.write_to_be_bytes(buf)
+            }
+            4 => {
+                let u32 = UnsignedByteFieldU32::try_from(*self).unwrap();
+                u32.write_to_be_bytes(buf)
+            }
+            8 => {
+                let u64 = UnsignedByteFieldU64::try_from(*self).unwrap();
+                u64.write_to_be_bytes(buf)
+            }
+            _ => {
+                // The API does not allow this.
+                panic!("unexpected written length");
+            }
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct GenericUnsignedByteField<TYPE> {
+    value: TYPE,
+}
+
+impl<TYPE> GenericUnsignedByteField<TYPE> {
+    pub const fn new(val: TYPE) -> Self {
+        Self { value: val }
+    }
+}
+
+impl<TYPE: ToBeBytes> UnsignedEnum for GenericUnsignedByteField<TYPE> {
+    fn size(&self) -> usize {
+        self.value.written_len()
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.size() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.size(),
+            });
+        }
+        buf[0..self.size()].copy_from_slice(self.value.to_be_bytes().as_ref());
+        Ok(self.value.written_len())
+    }
+}
+
+pub type UnsignedByteFieldEmpty = GenericUnsignedByteField<()>;
+pub type UnsignedByteFieldU8 = GenericUnsignedByteField<u8>;
+pub type UnsignedByteFieldU16 = GenericUnsignedByteField<u16>;
+pub type UnsignedByteFieldU32 = GenericUnsignedByteField<u32>;
+pub type UnsignedByteFieldU64 = GenericUnsignedByteField<u64>;
+
+pub type UbfU8 = UnsignedByteFieldU8;
+pub type UbfU16 = UnsignedByteFieldU16;
+pub type UbfU32 = UnsignedByteFieldU32;
+pub type UbfU64 = UnsignedByteFieldU64;
+
+impl From<UnsignedByteFieldU8> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU8) -> Self {
+        Self::new(1, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU8 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 1 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(1),
+            });
+        }
+        Ok(Self::new(value.value as u8))
+    }
+}
+
+impl From<UnsignedByteFieldU16> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU16) -> Self {
+        Self::new(2, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU16 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 2 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(2),
+            });
+        }
+        Ok(Self::new(value.value as u16))
+    }
+}
+
+impl From<UnsignedByteFieldU32> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU32) -> Self {
+        Self::new(4, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU32 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 4 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(4),
+            });
+        }
+        Ok(Self::new(value.value as u32))
+    }
+}
+
+impl From<UnsignedByteFieldU64> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU64) -> Self {
+        Self::new(8, value.value)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU64 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 8 {
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(8),
+            });
+        }
+        Ok(Self::new(value.value))
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::util::{
+        UnsignedByteField, UnsignedByteFieldError, UnsignedByteFieldU16, UnsignedByteFieldU32,
+        UnsignedByteFieldU64, UnsignedByteFieldU8, UnsignedEnum,
+    };
+    use crate::ByteConversionError;
+    use std::format;
+
+    #[test]
+    fn test_simple_u8() {
+        let u8 = UnsignedByteFieldU8::new(5);
+        assert_eq!(u8.size(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u8
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 1);
+        assert_eq!(buf[0], 5);
+        for i in 1..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u16() {
+        let u16 = UnsignedByteFieldU16::new(3823);
+        assert_eq!(u16.size(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u16
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 2);
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for i in 2..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u32() {
+        let u32 = UnsignedByteFieldU32::new(80932);
+        assert_eq!(u32.size(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u32
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 4);
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        for i in 4..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u64() {
+        let u64 = UnsignedByteFieldU64::new(5999999);
+        assert_eq!(u64.size(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u64
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 8);
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn conversions_u8() {
+        let u8 = UnsignedByteFieldU8::new(5);
+        let u8_type_erased = UnsignedByteField::from(u8);
+        assert_eq!(u8_type_erased.width, 1);
+        assert_eq!(u8_type_erased.value, 5);
+        let u8_conv_back =
+            UnsignedByteFieldU8::try_from(u8_type_erased).expect("conversion failed for u8");
+        assert_eq!(u8, u8_conv_back);
+        assert_eq!(u8_conv_back.value, 5);
+    }
+
+    #[test]
+    fn conversion_u8_fails() {
+        let field = UnsignedByteField::new(2, 60000);
+        let conv_fails = UnsignedByteFieldU8::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 2);
+                assert_eq!(expected, 1);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u16() {
+        let u16 = UnsignedByteFieldU16::new(64444);
+        let u16_type_erased = UnsignedByteField::from(u16);
+        assert_eq!(u16_type_erased.width, 2);
+        assert_eq!(u16_type_erased.value, 64444);
+        let u16_conv_back =
+            UnsignedByteFieldU16::try_from(u16_type_erased).expect("conversion failed for u16");
+        assert_eq!(u16, u16_conv_back);
+        assert_eq!(u16_conv_back.value, 64444);
+    }
+
+    #[test]
+    fn conversion_u16_fails() {
+        let field = UnsignedByteField::new(4, 75000);
+        let conv_fails = UnsignedByteFieldU16::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 4);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u32() {
+        let u32 = UnsignedByteFieldU32::new(75000);
+        let u32_type_erased = UnsignedByteField::from(u32);
+        assert_eq!(u32_type_erased.width, 4);
+        assert_eq!(u32_type_erased.value, 75000);
+        let u32_conv_back =
+            UnsignedByteFieldU32::try_from(u32_type_erased).expect("conversion failed for u32");
+        assert_eq!(u32, u32_conv_back);
+        assert_eq!(u32_conv_back.value, 75000);
+    }
+
+    #[test]
+    fn conversion_u32_fails() {
+        let field = UnsignedByteField::new(8, 75000);
+        let conv_fails = UnsignedByteFieldU32::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 8);
+                assert_eq!(expected, 4);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u64() {
+        let u64 = UnsignedByteFieldU64::new(5999999);
+        let u64_type_erased = UnsignedByteField::from(u64);
+        assert_eq!(u64_type_erased.width, 8);
+        assert_eq!(u64_type_erased.value, 5999999);
+        let u64_conv_back =
+            UnsignedByteFieldU64::try_from(u64_type_erased).expect("conversion failed for u64");
+        assert_eq!(u64, u64_conv_back);
+        assert_eq!(u64_conv_back.value, 5999999);
+    }
+
+    #[test]
+    fn conversion_u64_fails() {
+        let field = UnsignedByteField::new(4, 60000);
+        let conv_fails = UnsignedByteFieldU64::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 4);
+                assert_eq!(expected, 8);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u8_write() {
+        let u8 = UnsignedByteField::new(1, 5);
+        assert_eq!(u8.size(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        u8.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(buf[0], 5);
+        for i in 1..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u16_write() {
+        let u16 = UnsignedByteField::new(2, 3823);
+        assert_eq!(u16.size(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        u16.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for i in 2..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u32_write() {
+        let u32 = UnsignedByteField::new(4, 80932);
+        assert_eq!(u32.size(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        u32.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        for i in 4..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u64_write() {
+        let u64 = UnsignedByteField::new(8, 5999999);
+        assert_eq!(u64.size(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        u64.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn type_erased_u8_construction() {
+        let buf: [u8; 2] = [5, 10];
+        let u8 = UnsignedByteField::new_from_be_bytes(1, &buf).expect("construction failed");
+        assert_eq!(u8.width, 1);
+        assert_eq!(u8.value, 5);
+    }
+
+    #[test]
+    fn type_erased_u16_construction() {
+        let buf: [u8; 2] = [0x10, 0x15];
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf).expect("construction failed");
+        assert_eq!(u16.width, 2);
+        assert_eq!(u16.value, 0x1015);
+    }
+
+    #[test]
+    fn type_erased_u32_construction() {
+        let buf: [u8; 4] = [0x01, 0x02, 0x03, 0x04];
+        let u32 = UnsignedByteField::new_from_be_bytes(4, &buf).expect("construction failed");
+        assert_eq!(u32.width, 4);
+        assert_eq!(u32.value, 0x01020304);
+    }
+
+    #[test]
+    fn type_erased_u64_construction() {
+        let buf: [u8; 8] = [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08];
+        let u64 = UnsignedByteField::new_from_be_bytes(8, &buf).expect("construction failed");
+        assert_eq!(u64.width, 8);
+        assert_eq!(u64.value, 0x0102030405060708);
+    }
+
+    #[test]
+    fn type_u16_target_buf_too_small() {
+        let u16 = UnsignedByteFieldU16::new(500);
+        let mut buf: [u8; 1] = [0; 1];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 1);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("invalid exception")
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u16_target_buf_too_small() {
+        let u16 = UnsignedByteField::new(2, 500);
+        let mut buf: [u8; 1] = [0; 1];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 1);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("invalid exception {}", err)
+            }
+        }
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf);
+        assert!(u16.is_err());
+        let err = u16.unwrap_err();
+        if let UnsignedByteFieldError::ByteConversionError(
+            ByteConversionError::FromSliceTooSmall { found, expected },
+        ) = err
+        {
+            assert_eq!(expected, 2);
+            assert_eq!(found, 1);
+        } else {
+            panic!("unexpected exception {}", err);
+        }
+    }
+
+    #[test]
+    fn type_u32_target_buf_too_small() {
+        let u16 = UnsignedByteFieldU32::new(500);
+        let mut buf: [u8; 3] = [0; 3];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 3);
+                assert_eq!(expected, 4);
+            }
+            _ => {
+                panic!("invalid exception")
+            }
+        }
+    }
+}