Merge pull request 'clippy' (#190) from clippy into main

Reviewed-on: #190

.github/workflows/ci.yml

@@ -1,113 +1,77 @@
-on: [push]
-
 name: ci
+on: [push, pull_request]
 
 jobs:
   check:
-    name: Check
+    name: Check build
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          profile: minimal
-          toolchain: stable
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --release
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo check --release
 
-  msrv:
-    name: Check with MSRV
+  test:
+    name: Run Tests
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: 1.65.0
-          override: true
-          profile: minimal
-      - uses: actions-rs/cargo@v1
-        with:
-          command: check
-          args: --release
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - name: Install nextest
+        uses: taiki-e/install-action@nextest
+      - run: cargo nextest run --all-features
+      - run: cargo test --doc
+
+  msrv:
+    name: Check MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@1.83
+      - run: cargo check --release
 
   cross-check:
-    name: Check Cross
+    name: Check Cross-Compilation
     runs-on: ubuntu-latest
     strategy:
       matrix:
         target:
           - armv7-unknown-linux-gnueabihf
+          - thumbv6m-none-eabi
           - thumbv7em-none-eabihf
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
-          toolchain: stable
-          target: ${{ matrix.target }}
-          override: true
-      - uses: actions-rs/cargo@v1
-        with:
-          use-cross: true
-          command: check
-          args: --release --target=${{ matrix.target }} --no-default-features
+          targets: "armv7-unknown-linux-gnueabihf, thumbv7em-none-eabihf, thumbv6m-none-eabi"
+      - run: cargo check --release --target=${{matrix.target}} --no-default-features
 
   fmt:
-    name: Rustfmt
+    name: Check formatting
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
-          toolchain: stable
-          override: true
-      - run: rustup component add rustfmt
-      - uses: actions-rs/cargo@v1
-        with:
-          command: fmt
-          args: --all -- --check
+          components: rustfmt
+      - run: cargo fmt --all -- --check
 
-  check-doc:
+  docs:
     name: Check Documentation Build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
-        with:
-          toolchain: nightly
-          override: true
-          profile: minimal
-      - uses: actions-rs/cargo@v1
-        with:
-          command: doc
-          args: --all-features
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@nightly
+      - run: RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features
 
   clippy:
     name: Clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
         with:
-          profile: minimal
-          toolchain: stable
-      - run: rustup component add clippy
-      - uses: actions-rs/cargo@v1
-        with:
-          command: clippy
-          args: -- -D warnings
-
-  ci:
-      if: ${{ success() }}
-      # all new jobs must be added to this list
-      needs: [check, fmt, clippy]
-      runs-on: ubuntu-latest
-      steps:
-        - name: CI succeeded
-          run: exit 0
+          components: clippy
+      - run: cargo clippy -- -D warnings

CHANGELOG.md

@@ -8,6 +8,189 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.17.0] 2025-11-06
+
+## Changed
+
+- `CdsCommon` renamed to `CdsBase`
+- cfdp: Removed `FileDirectiveType` variant `*Pdu` suffix
+- ecss: Renamed `Subservice` to `MessageSubtypeId`
+- Simplified CDS short timestamp, contains one less field which reduced serialization length.
+- Renamed `UnsignedEnum::value` to `UnsignedEnum::value_raw`, `value` is reserved for the `const`
+  value getter.
+- Renamed `CcsdsPrimaryHeader::from_composite_fields` to
+  `CcsdsPrimaryHeader::new_from_composite_fields`
+- Renamed `PusPacket::service` to `PusPacket::service_type_id` and `PusPacket::subservice` to
+  `PusPacket::message_subtype_id`. Also added `PusPacket::message_type_id`. Performed the same
+  change for the ECSS PUS C secondary header traits.
+
+## Added
+
+- Added `CcsdsPacketCreator`, `CcsdsPacketReader`, `CcsdsPacketCreatorWithReservedData` and
+  `CcsdsPacketCreatorOwned` which simplify the process of creating full CCSDS space packets.
+- Added new optional `portable-atomic` because portable atomics might not work on every
+  architecture in addition to requiring atomic CAS support enabled inside for the crate.
+
+## Fixed
+
+- All `core::sync::Atomic?` usages are feature gated properly to allow compilation on systems
+  without atomic CAS.
+
+# [v0.16.1] 2025-09-26
+
+## Fixed
+
+`SpHeader::packet_len` is public now.
+
+# [v0.16.0] 2025-09-24
+
+- Bump Rust MSRV to v1.83
+
+## Changed
+
+- `PusTcCreator` has its own `service`, `subservice` and `apid` methods and does not require trait
+  imports anymore.
+- CFDP NAK PDU `SegmentRequestIter` is not generic over the file size anymore. Instead, the
+  iterator returns pairs of `u64` for both large and normal file size.
+- `PusVersion::VersionNotSupported` contains raw version number instead of `PusVersion` enum now
+  to make it more flexible.
+- `pus_version` API now returns a `Result<PusVersion, u8>` instead of a `PusVersion` to allow
+  modelling invalid version numbers properly.
+- Renamed `CcsdsPacket::total_len` to `CcsdsPacket::packet_len`
+- Renamed `SequenceCountProvider` to `SequenceCounter`
+- Renamed `SeqCountProviderSimple` to `SequenceCounterSimple`
+- Renamed `CcsdsSimpleSeqCountProvider` to `SequenceCounterCcsdsSimple`
+- Renamed `SeqCountProviderSync` to `SequenceCounterSync`
+- Renamed `PusPacket::opt_crc16` to `PusPacket::checksum`
+- Renamed `PacketSequenceCtrl` to `PacketSequenceControl`
+- ECSS checksum generation is now optional as specified in the standard. Added `has_checksum`
+  parameters for ECSS TM/TC creators and readers to reflect this.
+- APID is represented by `arbitrary-int::u11` while the sequence count is represented by
+  `arbitrary-int::u14`. A lot of corresponding checks were removed because the type now ensure
+  value validity.
+- ACK field changed from `u8` to `AckFlags` structure.
+- PUS version raw representation is `u4` now.
+- SC time reference status representation is `u4` now.
+- Renamed `ptype` to `packet_type`
+- Renamed `PduHeader::new_no_file_data` to `PduHeader::new_for_file_directive`
+- Renamd `FinishedPduCreator::new_generic` to `new` and `new_default` to `new_no_error`
+
+## Removed
+
+- `PusVersion::Invalid`, which will be modelled with `Result<PusVersion, u8>` now.
+
+## Added
+
+- `cfdp::pdu::ack::InvalidAckedDirectiveCodeError` which is returned by the `AckPdu` constructor.
+- `cfdp::pdu::nak::NakPduCreatorWithReservedSegReqsBuf` constructor which exposes the segment
+  request buffer mutably to avoid the need for a separate segment request buffer.
+- `SpHeader::packet_len` direct method.
+- `AckFlags` which is implemented with `bitbybit::bitfield`
+- `ApidOutOfRangeError` and `SequenceCountOutOfRangeError`
+- Added PUS A legacy support for telecommands inside the `ecss.tc_pus_a` module
+- Added `SequenceCounter::increment_mut` and `SequenceCounter::get_and_increment_mut`
+- Implemented `SequenceCounter` for `Atomic` unsigned types and references of them
+- `PusPacket::has_checksum` and `WritablePusPacket::has_checksum`
+- PUS TC builder API, either via `PusTcBuilder::new`, or `PusTcCreator::builder`
+
+# [v0.15.0] 2025-07-18
+
+## Added
+
+- `PusTcCreatorWithReservedAppData` and `PusTmCreatorWithReservedSourceData` constructor variants
+  which allow writing source/app data into the serialization buffer directly without
+  requiring an extra buffer.
+
+# [v0.14.0] 2025-05-10
+
+## Changed
+
+- Moved CRC constants/implementations to dedicated `crc` module.
+- `crc::CRC_CCITT_FALSE_NO_TABLE` and `crc::CRC_CCITT_FALSE_BIG_TABLE` variants.
+- Renamed `PusPacket::crc16` to `PusPacket::opt_crc16`.
+
+## Added
+
+- `WritablePusPacket::write_to_bytes_crc_no_table` and `WritablePusPacket::write_to_bytes_no_crc`
+  variants.
+- `PusTmReader::new_crc_no_table` and `PusTcReader::new_crc_no_table` variants.
+- `crc16` methods for PUS TM and PUS TC reader.
+- PUS TM and PUS TC reader now return the reader instance directly instead of a tuple of the reader
+  and the read size. The instance `total_len` method can be used to retrieve the read lenght.
+
+# [v0.13.1] 2025-03-21
+
+- Bugfix due to operator precendence for `PusTcSecondaryHeader::pus_version`,
+  `PusTcSecondaryHeaderWithoutTimestamp::pus_version`, `CdsTime::from_bytes_with_u16_days` and
+  `CdsTime::from_bytes_with_u24_days`
+
+# [v0.13.0] 2024-11-08
+
+- Bumped MSRV to 1.81.0
+- Bump `zerocopy` to v0.8.0
+- Bump `thiserror` to v2.0.0
+
+## Changed
+
+- Migrated all Error implementations to thiserror, improved some naming and error handling in
+  general
+
+# [v0.12.0] 2024-09-10
+
+- Bumped MSRV to 1.70.0
+
+## Added
+
+- Added new `cfdp::tlv::TlvOwned` type which erases the lifetime and is clonable.
+- Dedicated `cfdp::tlv::TlvLvDataTooLarge` error struct for APIs where this is the only possible
+  API error.
+- Added File Data PDU API which expects the expected file data size and then exposes the unwritten
+  file data field as a mutable slice. This allows to read data from the virtual file system
+  API to the file data buffer without an intermediate buffer.
+- Generic `EofPdu::new` constructor.
+- Added generic sequence counter module.
+- Added `MsgToUserTlv::to_tlv` converter which reduced the type and converts
+  it to a generic `Tlv`.
+- Implemented `From<MsgToUserTlv> for Tlv` converter trait.
+- Added CFDP maximum file segment length calculator method `calculate_max_file_seg_len_for_max_packet_len_and_pdu_header`
+
+## Added and Changed
+
+- Added new `ReadableTlv` to avoid some boilerplate code and have a common abstraction implemented
+  for both `Tlv` and `TlvOwned` to read the raw TLV data field and its length.
+- Replaced `cfdp::tlv::TlvLvError` by `cfdp::tlv::TlvLvDataTooLarge` where applicable.
+
+## Fixed
+
+- Fixed an error in the EOF writer which wrote the fault location to the wrong buffer position.
+- cfdp `ConditionCode::CheckLimitReached` previous had the wrong numerical value of `0b1001` (9)
+  and now has the correct value of `0b1010` (10).
+
+## Changed
+
+- Minor documentation build updates.
+- Increased delegate version range to v0.13
+
+# [v0.11.2] 2024-05-19
+
+- Bumped MSRV to 1.68.2
+
+## Fixed
+
+- Removed `defmt::Format` impl for `MetadataPduCreator` which seems to be problematic.
+
+# [v0.11.1] 2024-04-22
+
+## Fixed
+
+- The default data length for for `SpHeader` constructors where the data field length is not
+  specified is now 0.
+- The `SpHeader::new_from_fields` is public now.
+
+## Added
+
+- `SpHeader::to_vec` method.
+
 # [v0.11.0] 2024-04-16
 
 ## Changed
@@ -494,3 +677,13 @@ The timestamp of `PusTm` is now optional. See Added and Changed section for deta
 
 Initial release with CCSDS Space Packet Primary Header implementation and basic PUS TC and TM
 implementations.
+
+[unreleased]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.17.0...HEAD
+[v0.17.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.16.1...v0.17.0
+[v0.16.1]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.16.0...v0.16.1
+[v0.16.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.15.0...v0.16.0
+[v0.15.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.14.0...v0.15.0
+[v0.14.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.13.1...v0.14.0
+[v0.13.1]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.13.0...v0.13.1
+[v0.13.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.12.0...v0.13.0
+[v0.12.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.11.2...v0.12.0

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "spacepackets"
-version = "0.11.0"
+version = "0.17.0"
 edition = "2021"
-rust-version = "1.65"
+rust-version = "1.83"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]
 description = "Generic implementations for various CCSDS and ECSS packet standards"
 homepage = "https://egit.irs.uni-stuttgart.de/rust/spacepackets"
@@ -14,57 +14,34 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 
 [dependencies]
 crc = "3"
-delegate = ">=0.8, <0.11"
+delegate = "0.13"
+paste = "1"
+zerocopy = { version = "0.8", features = ["derive"] }
+thiserror = { version = "2", default-features = false }
+num_enum = { version = "0.7", default-features = false }
+num-traits = { version = "0.2", default-features = false }
+serde = { version = "1", optional = true, default-features = false, features = ["derive"] }
+arbitrary-int = { version = "2" }
+portable-atomic = { version = "1", optional = true }
+bitbybit = "1.4"
 
-[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"
-optional = true
-default-features = false
-features = ["derive"]
-
-[dependencies.time]
-version = "0.3"
-default-features = false
-optional = true
-
-[dependencies.chrono]
-version = "0.4"
-default-features = false
-optional = true
-
-[dependencies.num-traits]
-version = "0.2"
-default-features = false
-
-[dependencies.defmt]
-version = "0.3"
-optional = true
-
-[dev-dependencies]
-postcard = "1"
-chrono = "0.4"
+time = { version = "0.3", default-features = false, optional = true }
+chrono = { version = "0.4", default-features = false, optional = true }
+defmt = { version = "1", default-features = false, optional = true }
 
 [features]
 default = ["std"]
-std = ["chrono/std", "chrono/clock", "alloc", "thiserror"]
-serde = ["dep:serde", "chrono/serde"]
-alloc = ["postcard/alloc", "chrono/alloc"]
-chrono = ["dep:chrono"]
+std = ["alloc", "chrono/std", "chrono/clock", "thiserror/std"]
+portable-atomic = ["dep:portable-atomic", "portable-atomic/require-cas"]
+defmt = ["dep:defmt", "arbitrary-int/defmt"]
+serde = ["dep:serde", "chrono?/serde", "arbitrary-int/serde"]
+alloc = ["chrono?/alloc", "defmt?/alloc", "serde?/alloc"]
 timelib = ["dep:time"]
-defmt = ["dep:defmt"]
+
+[dev-dependencies]
+postcard = { version = "1", features = ["alloc"] }
+chrono = "0.4"
 
 [package.metadata.docs.rs]
 all-features = true
-rustdoc-args = ["--cfg", "docs_rs", "--generate-link-to-definition"]
+rustdoc-args = ["--generate-link-to-definition"]

FUNDING.yml

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

README.md

@@ -1,7 +1,7 @@
 [![Crates.io](https://img.shields.io/crates/v/spacepackets)](https://crates.io/crates/spacepackets)
 [![docs.rs](https://img.shields.io/docsrs/spacepackets)](https://docs.rs/spacepackets)
 [![ci](https://github.com/us-irs/spacepackets-rs/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/us-irs/spacepackets-rs/actions/workflows/ci.yml)
-[![coverage](https://shields.io/endpoint?url=https://absatsw.irs.uni-stuttgart.de/projects/spacepackets/coverage-rs/latest/coverage.json)](https://absatsw.irs.uni-stuttgart.de/projects/spacepackets/coverage-rs/latest/index.html)
+[![matrix chat](https://img.shields.io/matrix/sat-rs%3Amatrix.org)](https://matrix.to/#/#sat-rs:matrix.org)
 
 ECSS and CCSDS Spacepackets
 ======
@@ -43,6 +43,9 @@ Currently, this includes the following components:
  - [`timelib`](https://crates.io/crates/time): Add basic support for the `time` time library.
  - [`defmt`](https://defmt.ferrous-systems.com/): Add support for the `defmt` by adding the
    [`defmt::Format`](https://defmt.ferrous-systems.com/format) derive on many types.
+ - [`portable-atomic`](https://github.com/taiki-e/portable-atomic): Basic support for `portable-atomic`
+   crate in addition to the support for core atomic types. This support requires atomic CAS support
+   enabled in the portable atomic crate.
 
 # Examples
 
@@ -51,13 +54,21 @@ usage examples.
 
 # Coverage
 
-Coverage was generated using [`grcov`](https://github.com/mozilla/grcov). If you have not done so
-already, install the `llvm-tools-preview`:
+Coverage can be generated using [`llvm-cov`](https://github.com/taiki-e/cargo-llvm-cov). If you have not done so
+already, install the tool:
 
 ```sh
-rustup component add llvm-tools-preview
-cargo install grcov --locked
+cargo +stable install cargo-llvm-cov --locked
 ```
 
-After that, you can simply run `coverage.py` to test the project with coverage. You can optionally
-supply the `--open` flag to open the coverage report in your webbrowser.
+After this, you can run `cargo llvm-cov nextest` to run all the tests and display coverage.
+
+# Miri
+
+You can run the [`miri`](https://github.com/rust-lang/miri) tool on this library to check for
+undefined behaviour (UB). This library does not use use any `unsafe` code blocks, but `miri` could
+still catch UB from used libraries.
+
+```sh
+cargo +nightly miri nextest run --all-features
+```

automation/Jenkinsfile

@@ -21,7 +21,9 @@ pipeline {
     }
     stage('Docs') {
         steps {
-          sh 'cargo +nightly doc --all-features'
+          sh """
+            RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features
+          """
         }
     }
     stage('Rustfmt') {

coverage.py

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

justfile

@@ -0,0 +1,36 @@
+all: check build embedded test clippy check-fmt docs coverage
+
+clippy:
+  cargo clippy -- -D warnings
+
+fmt:
+  cargo fmt --all
+
+check-fmt:
+  cargo fmt --all -- --check
+
+check:
+  cargo check --all-features
+
+embedded:
+  cargo build --target thumbv7em-none-eabihf --no-default-features
+  cargo build --target thumbv6m-none-eabi --no-default-features
+
+test:
+  cargo nextest r --all-features
+  cargo test --doc
+
+build:
+  cargo build --all-features
+
+docs:
+  RUSTDOCFLAGS="--cfg docsrs -Z unstable-options --generate-link-to-definition" cargo +nightly doc --all-features
+
+docs-html:
+  RUSTDOCFLAGS="--cfg docsrs -Z unstable-options --generate-link-to-definition" cargo +nightly doc --all-features --open
+
+coverage:
+  cargo llvm-cov nextest
+
+coverage-html:
+  cargo llvm-cov nextest --html --open

release-checklist.md

@@ -4,7 +4,9 @@ Checklist for new releases
 # Pre-Release
 
 1. Make sure any new modules are documented sufficiently enough and check docs with
-   `cargo +nightly doc --all-features --config 'build.rustdocflags=["--cfg", "docs_rs"]' --open`.
+   `RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features --open`
+   or `cargo +nightly doc --all-features --config 'build.rustdocflags=["--cfg", "docsrs" --generate-link-to-definition"]' --open`
+   (was problematic on more recent nightly versions).
 2. Bump version specifier in `Cargo.toml`.
 3. Update `CHANGELOG.md`: Convert `unreleased` section into version section with date and add new
    `unreleased` section.

src/cfdp/lv.rs

@@ -1,5 +1,4 @@
 //! Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
-use crate::cfdp::TlvLvError;
 use crate::ByteConversionError;
 use core::str::Utf8Error;
 #[cfg(feature = "serde")]
@@ -7,6 +6,9 @@ use serde::{Deserialize, Serialize};
 #[cfg(feature = "std")]
 use std::string::String;
 
+use super::TlvLvDataTooLargeError;
+
+/// Minmum length of a CFDP length-value structure in bytes.
 pub const MIN_LV_LEN: usize = 1;
 
 /// Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
@@ -62,10 +64,14 @@ pub(crate) fn generic_len_check_deserialization(
 }
 
 impl<'data> Lv<'data> {
+    /// Minimum length of a LV structure in bytes.
+    pub const MIN_LEN: usize = MIN_LV_LEN;
+
+    /// Generic constructor.
     #[inline]
-    pub fn new(data: &[u8]) -> Result<Lv, TlvLvError> {
+    pub fn new(data: &[u8]) -> Result<Lv<'_>, TlvLvDataTooLargeError> {
         if data.len() > u8::MAX as usize {
-            return Err(TlvLvError::DataTooLarge(data.len()));
+            return Err(TlvLvDataTooLargeError(data.len()));
         }
         Ok(Lv {
             data,
@@ -85,7 +91,7 @@ impl<'data> Lv<'data> {
     /// Helper function to build a string LV. This is especially useful for the file or directory
     /// path LVs
     #[inline]
-    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvError> {
+    pub fn new_from_str(str_slice: &str) -> Result<Lv<'_>, TlvLvDataTooLargeError> {
         Self::new(str_slice.as_bytes())
     }
 
@@ -93,7 +99,7 @@ impl<'data> Lv<'data> {
     /// path LVs
     #[cfg(feature = "std")]
     #[inline]
-    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvError> {
+    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvDataTooLargeError> {
         Self::new(string.as_bytes())
     }
 
@@ -115,6 +121,7 @@ impl<'data> Lv<'data> {
         self.data.len() == 0
     }
 
+    /// Raw value part of the LV.
     #[inline]
     pub fn value(&self) -> &[u8] {
         self.data
@@ -176,11 +183,11 @@ impl<'data> Lv<'data> {
 }
 
 #[cfg(test)]
-pub mod tests {
-    use super::*;
+mod tests {
     use alloc::string::ToString;
 
-    use crate::cfdp::TlvLvError;
+    use super::*;
+
     use crate::ByteConversionError;
     use std::string::String;
 
@@ -271,15 +278,11 @@ pub mod tests {
         let lv = Lv::new(&data_big);
         assert!(lv.is_err());
         let error = lv.unwrap_err();
-        if let TlvLvError::DataTooLarge(size) = error {
-            assert_eq!(size, u8::MAX as usize + 1);
-            assert_eq!(
-                error.to_string(),
-                "data with size 256 larger than allowed 255 bytes"
-            );
-        } else {
-            panic!("invalid exception {:?}", error)
-        }
+        assert_eq!(error.0, u8::MAX as usize + 1);
+        assert_eq!(
+            error.to_string(),
+            "data with size 256 larger than allowed 255 bytes"
+        );
     }
 
     #[test]

src/cfdp/mod.rs

@@ -1,11 +1,8 @@
 //! Low-level CCSDS File Delivery Protocol (CFDP) support according to [CCSDS 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf).
 use crate::ByteConversionError;
-use core::fmt::{Display, Formatter};
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-#[cfg(feature = "std")]
-use std::error::Error;
 
 pub mod lv;
 pub mod pdu;
@@ -16,39 +13,55 @@ 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)]
+/// PDU type.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum PduType {
+    /// File directive PDU.
     FileDirective = 0,
+    /// File data PDU.
     FileData = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// PDU direction.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum Direction {
+    /// Going towards the file receiver.
     TowardsReceiver = 0,
+    /// Going towards the file sender.
     TowardsSender = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// PDU transmission mode.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum TransmissionMode {
+    /// Acknowledged (class 1) transfer.
     Acknowledged = 0,
+    /// Unacknowledged (class 2) transfer.
     Unacknowledged = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// CRC flag.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum CrcFlag {
+    /// No CRC for the packet.
     NoCrc = 0,
+    /// Packet has CRC.
     WithCrc = 1,
 }
 
@@ -71,52 +84,76 @@ impl From<CrcFlag> for bool {
 }
 
 /// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum SegmentMetadataFlag {
+    /// Segment metadata not present.
     NotPresent = 0,
+    /// Segment metadata present.
     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)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum SegmentationControl {
+    /// No record boundary preservation.
     NoRecordBoundaryPreservation = 0,
+    /// With record boundary preservation.
     WithRecordBoundaryPreservation = 1,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// Fault handler codes according to the CFDP standard.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u3, exhaustive = false)]
 #[repr(u8)]
 pub enum FaultHandlerCode {
+    /// Notice of cancellation fault handler code.
     NoticeOfCancellation = 0b0001,
+    /// Notice of suspension fault handler code.
     NoticeOfSuspension = 0b0010,
+    /// Ignore error fault handler code.
     IgnoreError = 0b0011,
+    /// Abandon transaction fault handler code.
     AbandonTransaction = 0b0100,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// CFDP condition codes.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u4, exhaustive = false)]
 #[repr(u8)]
 pub enum ConditionCode {
     /// This is not an error condition for which a faulty handler override can be specified
     NoError = 0b0000,
+    /// Positive acknowledgement limit reached.
     PositiveAckLimitReached = 0b0001,
+    /// Keep-alive limit reached.
     KeepAliveLimitReached = 0b0010,
+    /// Invalid transmission mode.
     InvalidTransmissionMode = 0b0011,
+    /// Filestore rejection.
     FilestoreRejection = 0b0100,
+    /// File checksum error.
     FileChecksumFailure = 0b0101,
+    /// File size error.
     FileSizeError = 0b0110,
+    /// NAK limit reached.
     NakLimitReached = 0b0111,
+    /// Inactivity detected.
     InactivityDetected = 0b1000,
-    CheckLimitReached = 0b1001,
+    /// Check limit reached.
+    CheckLimitReached = 0b1010,
+    /// Unsupported checksum type.
     UnsupportedChecksumType = 0b1011,
     /// Not an actual fault condition for which fault handler overrides can be specified
     SuspendRequestReceived = 0b1110,
@@ -124,9 +161,11 @@ pub enum ConditionCode {
     CancelRequestReceived = 0b1111,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// Large file flag.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum LargeFileFlag {
     /// 32 bit maximum file size and FSS size
@@ -136,14 +175,16 @@ pub enum LargeFileFlag {
 }
 
 /// Transaction status for the ACK PDU field according to chapter 5.2.4 of the CFDP standard.
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u2, exhaustive = true)]
 #[repr(u8)]
 pub enum TransactionStatus {
     /// Transaction is not currently active and the CFDP implementation does not retain a
     /// transaction history.
     Undefined = 0b00,
+    /// Transaction is currently active.
     Active = 0b01,
     /// Transaction was active in the past and was terminated.
     Terminated = 0b10,
@@ -154,98 +195,70 @@ pub enum TransactionStatus {
 
 /// Checksum types according to the
 /// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/)
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum ChecksumType {
     /// Modular legacy checksum
     Modular = 0,
+    /// CRC32 Proximity-1.
     Crc32Proximity1 = 1,
+    /// CRC32C.
     Crc32C = 2,
-    /// Polynomial: 0x4C11DB7. Preferred checksum for now.
+    /// CRC32. Polynomial: 0x4C11DB7. Preferred checksum for now.
     Crc32 = 3,
+    /// Null checksum (no checksum).
+    #[default]
     NullChecksum = 15,
 }
 
-impl Default for ChecksumType {
-    fn default() -> Self {
-        Self::NullChecksum
-    }
-}
-
+/// Raw null checksum.
 pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+/// TLV or LV data larger than allowed [u8::MAX].
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[error("data with size {0} larger than allowed {max} bytes", max = u8::MAX)]
+pub struct TlvLvDataTooLargeError(pub usize);
+
+/// First value: Found value. Second value: Expected value if there is one.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[error("invalid TLV type field, found {found}, expected {expected:?}")]
+pub struct InvalidTlvTypeFieldError {
+    found: u8,
+    expected: Option<u8>,
+}
+
+/// Generic TLV/LV error.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum TlvLvError {
-    DataTooLarge(usize),
-    ByteConversion(ByteConversionError),
-    /// First value: Found value. Second value: Expected value if there is one.
-    InvalidTlvTypeField {
-        found: u8,
-        expected: Option<u8>,
-    },
-    /// Logically invalid value length detected. The value length may not exceed 255 bytes.
-    /// Depending on the concrete TLV type, the value length may also be logically invalid.
+    /// Data too large error.
+    #[error("{0}")]
+    DataTooLarge(#[from] TlvLvDataTooLargeError),
+    /// Byte conversion error.
+    #[error("byte conversion error: {0}")]
+    ByteConversion(#[from] ByteConversionError),
+    /// Invalid TLV type field error.
+    #[error("{0}")]
+    InvalidTlvTypeField(#[from] InvalidTlvTypeFieldError),
+    /// Invalid value length.
+    #[error("invalid value length {0}")]
     InvalidValueLength(usize),
     /// Only applies to filestore requests and responses. Second name was missing where one is
     /// expected.
+    #[error("second name missing for filestore request or response")]
     SecondNameMissing,
     /// Invalid action code for filestore requests or responses.
+    #[error("invalid action code {0}")]
     InvalidFilestoreActionCode(u8),
 }
 
-impl From<ByteConversionError> for TlvLvError {
-    fn from(value: ByteConversionError) -> Self {
-        Self::ByteConversion(value)
-    }
-}
-
-impl Display for TlvLvError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            TlvLvError::DataTooLarge(data_len) => {
-                write!(
-                    f,
-                    "data with size {} larger than allowed {} bytes",
-                    data_len,
-                    u8::MAX
-                )
-            }
-            TlvLvError::ByteConversion(e) => {
-                write!(f, "tlv or lv byte conversion: {}", e)
-            }
-            TlvLvError::InvalidTlvTypeField { found, expected } => {
-                write!(
-                    f,
-                    "invalid TLV type field, found {found}, expected {expected:?}"
-                )
-            }
-            TlvLvError::InvalidValueLength(len) => {
-                write!(f, "invalid value length {len}")
-            }
-            TlvLvError::SecondNameMissing => {
-                write!(f, "second name missing for filestore request or response")
-            }
-            TlvLvError::InvalidFilestoreActionCode(raw) => {
-                write!(f, "invalid filestore action code with raw value {raw}")
-            }
-        }
-    }
-}
-
-#[cfg(feature = "std")]
-impl Error for TlvLvError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        match self {
-            TlvLvError::ByteConversion(e) => Some(e),
-            _ => None,
-        }
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

src/cfdp/pdu/ack.rs

@@ -1,3 +1,4 @@
+//! # Acknowledgement (ACK) PDU packet implementation.
 use crate::{
     cfdp::{ConditionCode, CrcFlag, Direction, TransactionStatus},
     ByteConversionError,
@@ -10,6 +11,11 @@ use super::{
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// Invalid [FileDirectiveType] of the acknowledged PDU error.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, thiserror::Error)]
+#[error("invalid directive code of acknowledged PDU")]
+pub struct InvalidAckedDirectiveCodeError(pub FileDirectiveType);
+
 /// ACK PDU abstraction.
 ///
 /// For more information, refer to CFDP chapter 5.2.4.
@@ -24,21 +30,19 @@ pub struct AckPdu {
 }
 
 impl AckPdu {
+    /// Constructor.
     pub fn new(
         mut pdu_header: PduHeader,
         directive_code_of_acked_pdu: FileDirectiveType,
         condition_code: ConditionCode,
         transaction_status: TransactionStatus,
-    ) -> Result<Self, PduError> {
-        if directive_code_of_acked_pdu == FileDirectiveType::EofPdu {
+    ) -> Result<Self, InvalidAckedDirectiveCodeError> {
+        if directive_code_of_acked_pdu == FileDirectiveType::Eof {
             pdu_header.pdu_conf.direction = Direction::TowardsSender;
-        } else if directive_code_of_acked_pdu == FileDirectiveType::FinishedPdu {
+        } else if directive_code_of_acked_pdu == FileDirectiveType::Finished {
             pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
         } else {
-            return Err(PduError::InvalidDirectiveType {
-                found: directive_code_of_acked_pdu as u8,
-                expected: None,
-            });
+            return Err(InvalidAckedDirectiveCodeError(directive_code_of_acked_pdu));
         }
         // Force correct direction flag.
         let mut ack_pdu = Self {
@@ -51,6 +55,9 @@ impl AckPdu {
         Ok(ack_pdu)
     }
 
+    /// Constructor for an ACK PDU acknowledging an EOF PDU.
+    ///
+    /// Relevant for the file receiver.
     pub fn new_for_eof_pdu(
         pdu_header: PduHeader,
         condition_code: ConditionCode,
@@ -59,13 +66,16 @@ impl AckPdu {
         // Unwrap okay here, [new] can only fail on invalid directive codes.
         Self::new(
             pdu_header,
-            FileDirectiveType::EofPdu,
+            FileDirectiveType::Eof,
             condition_code,
             transaction_status,
         )
         .unwrap()
     }
 
+    /// Constructor for an ACK PDU acknowledging a Finished PDU.
+    ///
+    /// Relevant for the file sender.
     pub fn new_for_finished_pdu(
         pdu_header: PduHeader,
         condition_code: ConditionCode,
@@ -74,29 +84,38 @@ impl AckPdu {
         // Unwrap okay here, [new] can only fail on invalid directive codes.
         Self::new(
             pdu_header,
-            FileDirectiveType::FinishedPdu,
+            FileDirectiveType::Finished,
             condition_code,
             transaction_status,
         )
         .unwrap()
     }
 
+    /// PDU header.
+    #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
     }
 
+    /// Directive code of the acknowledged PDU.
+    #[inline]
     pub fn directive_code_of_acked_pdu(&self) -> FileDirectiveType {
         self.directive_code_of_acked_pdu
     }
 
+    /// Condition code.
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    /// Transaction status.
+    #[inline]
     pub fn transaction_status(&self) -> TransactionStatus {
         self.transaction_status
     }
 
+    #[inline]
     fn calc_pdu_datafield_len(&self) -> usize {
         if self.crc_flag() == CrcFlag::WithCrc {
             return 5;
@@ -104,6 +123,7 @@ impl AckPdu {
         3
     }
 
+    /// Construct [Self] from the provided byte slice.
     pub fn from_bytes(buf: &[u8]) -> Result<AckPdu, PduError> {
         let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
         let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
@@ -111,13 +131,13 @@ impl AckPdu {
         let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
             PduError::InvalidDirectiveType {
                 found: buf[current_idx],
-                expected: Some(FileDirectiveType::AckPdu),
+                expected: Some(FileDirectiveType::Ack),
             }
         })?;
-        if directive_type != FileDirectiveType::AckPdu {
+        if directive_type != FileDirectiveType::Ack {
             return Err(PduError::WrongDirectiveType {
                 found: directive_type,
-                expected: FileDirectiveType::AckPdu,
+                expected: FileDirectiveType::Ack,
             });
         }
         current_idx += 1;
@@ -128,8 +148,8 @@ impl AckPdu {
                     expected: None,
                 }
             })?;
-        if acked_directive_type != FileDirectiveType::EofPdu
-            && acked_directive_type != FileDirectiveType::FinishedPdu
+        if acked_directive_type != FileDirectiveType::Eof
+            && acked_directive_type != FileDirectiveType::Finished
         {
             return Err(PduError::InvalidDirectiveType {
                 found: acked_directive_type as u8,
@@ -140,27 +160,18 @@ impl AckPdu {
         let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
             .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
         let transaction_status = TransactionStatus::try_from(buf[current_idx] & 0b11).unwrap();
-        Self::new(
+        // Unwrap okay, validity of acked directive code was checked.
+        Ok(Self::new(
             pdu_header,
             acked_directive_type,
             condition_code,
             transaction_status,
         )
-    }
-}
-
-impl CfdpPdu for AckPdu {
-    fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
+        .unwrap())
     }
 
-    fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::AckPdu)
-    }
-}
-
-impl WritablePduPacket for AckPdu {
-    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+    /// Write [Self] to the provided buffer and returns the written size.
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
         let expected_len = self.len_written();
         if buf.len() < expected_len {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -170,11 +181,11 @@ impl WritablePduPacket for AckPdu {
             .into());
         }
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
-        buf[current_idx] = FileDirectiveType::AckPdu as u8;
+        buf[current_idx] = FileDirectiveType::Ack as u8;
         current_idx += 1;
 
         buf[current_idx] = (self.directive_code_of_acked_pdu as u8) << 4;
-        if self.directive_code_of_acked_pdu == FileDirectiveType::FinishedPdu {
+        if self.directive_code_of_acked_pdu == FileDirectiveType::Finished {
             // This is the directive subtype code. It needs to be set to 0b0001 if the ACK PDU
             // acknowledges a Finished PDU, and to 0b0000 otherwise.
             buf[current_idx] |= 0b0001;
@@ -188,11 +199,34 @@ impl WritablePduPacket for AckPdu {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    /// Length of the written PDU in bytes.
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for AckPdu {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::Ack)
+    }
+}
+
+impl WritablePduPacket for AckPdu {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::cfdp::{
@@ -211,10 +245,7 @@ mod tests {
         assert_eq!(ack_pdu.crc_flag(), expected_crc_flag);
         assert_eq!(ack_pdu.file_flag(), LargeFileFlag::Normal);
         assert_eq!(ack_pdu.pdu_type(), PduType::FileDirective);
-        assert_eq!(
-            ack_pdu.file_directive_type(),
-            Some(FileDirectiveType::AckPdu)
-        );
+        assert_eq!(ack_pdu.file_directive_type(), Some(FileDirectiveType::Ack));
         assert_eq!(ack_pdu.transmission_mode(), TransmissionMode::Acknowledged);
         assert_eq!(ack_pdu.direction(), expected_dir);
         assert_eq!(ack_pdu.source_id(), TEST_SRC_ID.into());
@@ -225,17 +256,17 @@ mod tests {
     #[test]
     fn test_basic() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new(
             pdu_header,
-            FileDirectiveType::FinishedPdu,
+            FileDirectiveType::Finished,
             ConditionCode::NoError,
             TransactionStatus::Active,
         )
         .expect("creating ACK PDU failed");
         assert_eq!(
             ack_pdu.directive_code_of_acked_pdu(),
-            FileDirectiveType::FinishedPdu
+            FileDirectiveType::Finished
         );
         verify_state(&ack_pdu, CrcFlag::NoCrc, Direction::TowardsReceiver);
     }
@@ -245,7 +276,7 @@ mod tests {
         transaction_status: TransactionStatus,
     ) {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_finished_pdu(pdu_header, condition_code, transaction_status);
         let mut buf: [u8; 64] = [0; 64];
         let res = ack_pdu.write_to_bytes(&mut buf);
@@ -254,8 +285,8 @@ mod tests {
         assert_eq!(written, ack_pdu.len_written());
         verify_raw_header(ack_pdu.pdu_header(), &buf);
 
-        assert_eq!(buf[7], FileDirectiveType::AckPdu as u8);
-        assert_eq!((buf[8] >> 4) & 0b1111, FileDirectiveType::FinishedPdu as u8);
+        assert_eq!(buf[7], FileDirectiveType::Ack as u8);
+        assert_eq!((buf[8] >> 4) & 0b1111, FileDirectiveType::Finished as u8);
         assert_eq!(buf[8] & 0b1111, 0b0001);
         assert_eq!(buf[9] >> 4 & 0b1111, condition_code as u8);
         assert_eq!(buf[9] & 0b11, transaction_status as u8);
@@ -267,15 +298,53 @@ mod tests {
         generic_serialization_test(ConditionCode::NoError, TransactionStatus::Active);
     }
 
+    #[test]
+    fn test_serialization_too_small() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
+        let ack_pdu = AckPdu::new(
+            pdu_header,
+            FileDirectiveType::Finished,
+            ConditionCode::NoError,
+            TransactionStatus::Active,
+        )
+        .expect("creating ACK PDU failed");
+        if let Err(PduError::ByteConversion(ByteConversionError::ToSliceTooSmall {
+            found,
+            expected,
+        })) = ack_pdu.write_to_bytes(&mut [0; 5])
+        {
+            assert_eq!(found, 5);
+            assert_eq!(expected, ack_pdu.len_written());
+        } else {
+            panic!("serialization should have failed");
+        }
+    }
+
     #[test]
     fn test_serialization_fs_error() {
         generic_serialization_test(ConditionCode::FileSizeError, TransactionStatus::Terminated);
     }
+    #[test]
+    fn test_invalid_directive_code_of_acked_pdu() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
+        assert_eq!(
+            AckPdu::new(
+                pdu_header,
+                FileDirectiveType::Metadata,
+                ConditionCode::NoError,
+                TransactionStatus::Active,
+            )
+            .unwrap_err(),
+            InvalidAckedDirectiveCodeError(FileDirectiveType::Metadata)
+        );
+    }
 
     #[test]
     fn test_deserialization() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_finished_pdu(
             pdu_header,
             ConditionCode::NoError,
@@ -290,7 +359,7 @@ mod tests {
     #[test]
     fn test_with_crc() {
         let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_finished_pdu(
             pdu_header,
             ConditionCode::NoError,
@@ -307,7 +376,7 @@ mod tests {
     #[test]
     fn test_for_eof_pdu() {
         let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_eof_pdu(
             pdu_header,
             ConditionCode::NoError,
@@ -315,7 +384,7 @@ mod tests {
         );
         assert_eq!(
             ack_pdu.directive_code_of_acked_pdu(),
-            FileDirectiveType::EofPdu
+            FileDirectiveType::Eof
         );
         verify_state(&ack_pdu, CrcFlag::WithCrc, Direction::TowardsSender);
     }
@@ -324,7 +393,7 @@ mod tests {
     #[cfg(feature = "serde")]
     fn test_ack_pdu_serialization() {
         let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let ack_pdu = AckPdu::new_for_eof_pdu(
             pdu_header,
             ConditionCode::NoError,

src/cfdp/pdu/eof.rs

@@ -1,3 +1,4 @@
+//! # End-of-File (EOF) PDU packet implementation.
 use crate::cfdp::pdu::{
     add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
     FileDirectiveType, PduError, PduHeader,
@@ -25,32 +26,58 @@ pub struct EofPdu {
 }
 
 impl EofPdu {
-    pub fn new_no_error(mut pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+    /// Constructor.
+    pub fn new(
+        mut pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        file_checksum: u32,
+        file_size: u64,
+        fault_location: Option<EntityIdTlv>,
+    ) -> Self {
         // Force correct direction flag.
         pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
         let mut eof_pdu = Self {
             pdu_header,
-            condition_code: ConditionCode::NoError,
+            condition_code,
             file_checksum,
             file_size,
-            fault_location: None,
+            fault_location,
         };
         eof_pdu.pdu_header.pdu_datafield_len = eof_pdu.calc_pdu_datafield_len() as u16;
         eof_pdu
     }
 
+    /// Constructor for no error EOF PDUs.
+    pub fn new_no_error(pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+        Self::new(
+            pdu_header,
+            ConditionCode::NoError,
+            file_checksum,
+            file_size,
+            None,
+        )
+    }
+
+    /// PDU header.
+    #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
     }
 
+    /// Condition code.
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    /// File checksum.
+    #[inline]
     pub fn file_checksum(&self) -> u32 {
         self.file_checksum
     }
 
+    /// File size.
+    #[inline]
     pub fn file_size(&self) -> u64 {
         self.file_size
     }
@@ -70,6 +97,7 @@ impl EofPdu {
         len
     }
 
+    /// Construct [Self] from the provided byte slice.
     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)?;
@@ -82,13 +110,13 @@ impl EofPdu {
         let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
             PduError::InvalidDirectiveType {
                 found: buf[current_idx],
-                expected: Some(FileDirectiveType::EofPdu),
+                expected: Some(FileDirectiveType::Eof),
             }
         })?;
-        if directive_type != FileDirectiveType::EofPdu {
+        if directive_type != FileDirectiveType::Eof {
             return Err(PduError::WrongDirectiveType {
                 found: directive_type,
-                expected: FileDirectiveType::EofPdu,
+                expected: FileDirectiveType::Eof,
             });
         }
         current_idx += 1;
@@ -113,20 +141,9 @@ impl EofPdu {
             fault_location,
         })
     }
-}
 
-impl CfdpPdu for EofPdu {
-    fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
-    }
-
-    fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::EofPdu)
-    }
-}
-
-impl WritablePduPacket for EofPdu {
-    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+    /// Write [Self] to the provided buffer and returns the written size.
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
         let expected_len = self.len_written();
         if buf.len() < expected_len {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -136,7 +153,7 @@ impl WritablePduPacket for EofPdu {
             .into());
         }
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
-        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        buf[current_idx] = FileDirectiveType::Eof as u8;
         current_idx += 1;
         buf[current_idx] = (self.condition_code as u8) << 4;
         current_idx += 1;
@@ -148,7 +165,7 @@ impl WritablePduPacket for EofPdu {
             &mut buf[current_idx..],
         )?;
         if let Some(fault_location) = self.fault_location {
-            current_idx += fault_location.write_to_bytes(buf)?;
+            current_idx += fault_location.write_to_bytes(&mut buf[current_idx..])?;
         }
         if self.crc_flag() == CrcFlag::WithCrc {
             current_idx = add_pdu_crc(buf, current_idx);
@@ -156,11 +173,34 @@ impl WritablePduPacket for EofPdu {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    /// Length of the written PDU in bytes.
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for EofPdu {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::Eof)
+    }
+}
+
+impl WritablePduPacket for EofPdu {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -171,19 +211,26 @@ mod tests {
     use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag, PduType, TransmissionMode};
     #[cfg(feature = "serde")]
     use crate::tests::generic_serde_test;
+    use crate::util::{UnsignedByteFieldU16, UnsignedEnum};
 
-    fn verify_state(&eof_pdu: &EofPdu, file_flag: LargeFileFlag) {
+    fn verify_state_no_error_no_crc(eof_pdu: &EofPdu, file_flag: LargeFileFlag) {
+        verify_state(eof_pdu, CrcFlag::NoCrc, file_flag, ConditionCode::NoError);
+    }
+
+    fn verify_state(
+        eof_pdu: &EofPdu,
+        crc_flag: CrcFlag,
+        file_flag: LargeFileFlag,
+        cond_code: ConditionCode,
+    ) {
         assert_eq!(eof_pdu.file_checksum(), 0x01020304);
         assert_eq!(eof_pdu.file_size(), 12);
-        assert_eq!(eof_pdu.condition_code(), ConditionCode::NoError);
+        assert_eq!(eof_pdu.condition_code(), cond_code);
 
-        assert_eq!(eof_pdu.crc_flag(), CrcFlag::NoCrc);
+        assert_eq!(eof_pdu.crc_flag(), crc_flag);
         assert_eq!(eof_pdu.file_flag(), file_flag);
         assert_eq!(eof_pdu.pdu_type(), PduType::FileDirective);
-        assert_eq!(
-            eof_pdu.file_directive_type(),
-            Some(FileDirectiveType::EofPdu)
-        );
+        assert_eq!(eof_pdu.file_directive_type(), Some(FileDirectiveType::Eof));
         assert_eq!(eof_pdu.transmission_mode(), TransmissionMode::Acknowledged);
         assert_eq!(eof_pdu.direction(), Direction::TowardsReceiver);
         assert_eq!(eof_pdu.source_id(), TEST_SRC_ID.into());
@@ -194,16 +241,16 @@ mod tests {
     #[test]
     fn test_basic() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         assert_eq!(eof_pdu.len_written(), pdu_header.header_len() + 2 + 4 + 4);
-        verify_state(&eof_pdu, LargeFileFlag::Normal);
+        verify_state_no_error_no_crc(&eof_pdu, LargeFileFlag::Normal);
     }
 
     #[test]
     fn test_serialization() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         let mut buf: [u8; 64] = [0; 64];
         let res = eof_pdu.write_to_bytes(&mut buf);
@@ -212,7 +259,7 @@ mod tests {
         assert_eq!(written, eof_pdu.len_written());
         verify_raw_header(eof_pdu.pdu_header(), &buf);
         let mut current_idx = eof_pdu.pdu_header().header_len();
-        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        buf[current_idx] = FileDirectiveType::Eof as u8;
         current_idx += 1;
         assert_eq!(
             (buf[current_idx] >> 4) & 0b1111,
@@ -235,7 +282,7 @@ mod tests {
     #[test]
     fn test_deserialization() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         let mut buf: [u8; 64] = [0; 64];
         eof_pdu.write_to_bytes(&mut buf).unwrap();
@@ -250,7 +297,7 @@ mod tests {
     #[test]
     fn test_write_to_vec() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         let mut buf: [u8; 64] = [0; 64];
         let written = eof_pdu.write_to_bytes(&mut buf).unwrap();
@@ -261,7 +308,7 @@ mod tests {
     #[test]
     fn test_with_crc() {
         let pdu_conf = common_pdu_conf(CrcFlag::WithCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         let mut buf: [u8; 64] = [0; 64];
         let written = eof_pdu.write_to_bytes(&mut buf).unwrap();
@@ -271,7 +318,7 @@ mod tests {
         buf[written - 1] -= 1;
         let crc: u16 = ((buf[written - 2] as u16) << 8) as u16 | buf[written - 1] as u16;
         let error = EofPdu::from_bytes(&buf).unwrap_err();
-        if let PduError::ChecksumError(e) = error {
+        if let PduError::Checksum(e) = error {
             assert_eq!(e, crc);
         } else {
             panic!("expected crc error");
@@ -281,9 +328,9 @@ mod tests {
     #[test]
     fn test_with_large_file_flag() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Large);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
-        verify_state(&eof_pdu, LargeFileFlag::Large);
+        verify_state_no_error_no_crc(&eof_pdu, LargeFileFlag::Large);
         assert_eq!(eof_pdu.len_written(), pdu_header.header_len() + 2 + 8 + 4);
     }
 
@@ -291,8 +338,52 @@ mod tests {
     #[cfg(feature = "serde")]
     fn test_eof_serde() {
         let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
-        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
         let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
         generic_serde_test(eof_pdu);
     }
+
+    fn generic_test_with_fault_location_and_error(crc: CrcFlag) {
+        let pdu_conf = common_pdu_conf(crc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_for_file_directive(pdu_conf, 0);
+        let eof_pdu = EofPdu::new(
+            pdu_header,
+            ConditionCode::FileChecksumFailure,
+            0x01020304,
+            12,
+            Some(EntityIdTlv::new(UnsignedByteFieldU16::new(5).into())),
+        );
+        let mut expected_len = pdu_header.header_len() + 2 + 4 + 4 + 4;
+        if crc == CrcFlag::WithCrc {
+            expected_len += 2;
+        }
+        // Entity ID TLV increaes length by 4.
+        assert_eq!(eof_pdu.len_written(), expected_len);
+        verify_state(
+            &eof_pdu,
+            crc,
+            LargeFileFlag::Normal,
+            ConditionCode::FileChecksumFailure,
+        );
+        let eof_vec = eof_pdu.to_vec().unwrap();
+        let eof_read_back = EofPdu::from_bytes(&eof_vec);
+        if let Err(e) = eof_read_back {
+            panic!("deserialization failed with: {e}")
+        }
+        let eof_read_back = eof_read_back.unwrap();
+        assert_eq!(eof_read_back, eof_pdu);
+        assert!(eof_read_back.fault_location.is_some());
+        assert_eq!(eof_read_back.fault_location.unwrap().entity_id().value(), 5);
+        assert_eq!(eof_read_back.fault_location.unwrap().entity_id().size(), 2);
+    }
+
+    #[test]
+    fn test_with_fault_location_and_error() {
+        generic_test_with_fault_location_and_error(CrcFlag::NoCrc);
+    }
+
+    #[test]
+    fn test_with_fault_location_and_error_and_crc() {
+        generic_test_with_fault_location_and_error(CrcFlag::WithCrc);
+    }
 }

src/cfdp/pdu/file_data.rs

@@ -1,3 +1,4 @@
+//! # File Data PDU packet implementation
 use crate::cfdp::pdu::{
     add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
     PduError, PduHeader,
@@ -10,16 +11,24 @@ use serde::{Deserialize, Serialize};
 
 use super::{CfdpPdu, FileDirectiveType, WritablePduPacket};
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+/// Record continuation state for segment metadata.
+#[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u2, exhaustive = true)]
 #[repr(u8)]
 pub enum RecordContinuationState {
+    /// No start and no end.
     NoStartNoEnd = 0b00,
+    /// Start without end.
     StartWithoutEnd = 0b01,
+    /// End without start.
     EndWithoutStart = 0b10,
+    /// Start and end.
     StartAndEnd = 0b11,
 }
 
+/// Segment metadata structure.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct SegmentMetadata<'seg_meta> {
@@ -28,6 +37,7 @@ pub struct SegmentMetadata<'seg_meta> {
 }
 
 impl<'seg_meta> SegmentMetadata<'seg_meta> {
+    /// Constructor.
     pub fn new(
         record_continuation_state: RecordContinuationState,
         metadata: Option<&'seg_meta [u8]>,
@@ -43,24 +53,30 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
         })
     }
 
+    /// Record continuation state.
+    #[inline]
     pub fn record_continuation_state(&self) -> RecordContinuationState {
         self.record_continuation_state
     }
 
+    /// Raw metadata slice.
+    #[inline]
     pub fn metadata(&self) -> Option<&'seg_meta [u8]> {
         self.metadata
     }
 
-    pub fn written_len(&self) -> usize {
+    /// Length of the written segment metadata structure.
+    #[inline]
+    pub fn len_written(&self) -> usize {
         // Map empty metadata to 0 and slice to its length.
         1 + self.metadata.map_or(0, |meta| meta.len())
     }
 
     pub(crate) fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
-        if buf.len() < self.written_len() {
+        if buf.len() < self.len_written() {
             return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
-                expected: self.written_len(),
+                expected: self.len_written(),
             });
         }
         buf[0] = ((self.record_continuation_state as u8) << 6)
@@ -68,7 +84,7 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
         if let Some(metadata) = self.metadata {
             buf[1..1 + metadata.len()].copy_from_slice(metadata)
         }
-        Ok(self.written_len())
+        Ok(self.len_written())
     }
 
     pub(crate) fn from_bytes(buf: &'seg_meta [u8]) -> Result<Self, ByteConversionError> {
@@ -92,130 +108,44 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
     }
 }
 
-/// 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> {
+struct FdPduBase<'seg_meta> {
     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)
+impl CfdpPdu for FdPduBase<'_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
     }
 
-    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)
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
     }
+}
 
-    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 {
+impl FdPduBase<'_> {
+    fn calc_pdu_datafield_len(&self, file_data_len: u64) -> usize {
         let mut len = core::mem::size_of::<u32>();
         if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
             len += 4;
         }
         if self.segment_metadata.is_some() {
-            len += self.segment_metadata.as_ref().unwrap().written_len()
+            len += self.segment_metadata.as_ref().unwrap().len_written()
         }
-        len += self.file_data.len();
+        len += file_data_len as usize;
         if self.crc_flag() == CrcFlag::WithCrc {
             len += 2;
         }
         len
     }
 
-    pub fn offset(&self) -> u64 {
-        self.offset
-    }
-
-    pub fn file_data(&self) -> &'file_data [u8] {
-        self.file_data
-    }
-
-    pub fn segment_metadata(&self) -> Option<&SegmentMetadata> {
-        self.segment_metadata.as_ref()
-    }
-
-    pub fn from_bytes<'buf: 'seg_meta + 'file_data>(buf: &'buf [u8]) -> Result<Self, PduError> {
-        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
-        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
-        let min_expected_len = current_idx + core::mem::size_of::<u32>();
-        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
-        let mut segment_metadata = None;
-        if pdu_header.seg_metadata_flag == SegmentMetadataFlag::Present {
-            segment_metadata = Some(SegmentMetadata::from_bytes(&buf[current_idx..])?);
-            current_idx += segment_metadata.as_ref().unwrap().written_len();
-        }
-        let (fss, offset) = read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
-        current_idx += fss;
-        if current_idx > full_len_without_crc {
-            return Err(ByteConversionError::FromSliceTooSmall {
-                found: current_idx,
-                expected: full_len_without_crc,
-            }
-            .into());
-        }
-        Ok(Self {
-            pdu_header,
-            segment_metadata,
-            offset,
-            file_data: &buf[current_idx..full_len_without_crc],
-        })
-    }
-}
-impl CfdpPdu for FileDataPdu<'_, '_> {
-    fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
-    }
-
-    fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        None
-    }
-}
-
-impl WritablePduPacket for FileDataPdu<'_, '_> {
-    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
-        if buf.len() < self.len_written() {
-            return Err(ByteConversionError::ToSliceTooSmall {
-                found: buf.len(),
-                expected: self.len_written(),
-            }
-            .into());
-        }
+    fn write_common_fields_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
         if self.segment_metadata.is_some() {
             current_idx += self
@@ -229,6 +159,139 @@ impl WritablePduPacket for FileDataPdu<'_, '_> {
             self.offset,
             &mut buf[current_idx..],
         )?;
+        Ok(current_idx)
+    }
+
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+}
+
+/// File Data PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FileDataPdu<'seg_meta, 'file_data> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    common: FdPduBase<'seg_meta>,
+    file_data: &'file_data [u8],
+}
+
+impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
+    /// Constructor for a file data PDU including segment metadata.
+    pub fn new_with_seg_metadata(
+        pdu_header: PduHeader,
+        segment_metadata: SegmentMetadata<'seg_meta>,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        Self::new(pdu_header, Some(segment_metadata), offset, file_data)
+    }
+
+    /// Constructor for a file data PDU without segment metadata.
+    pub fn new_no_seg_metadata(
+        pdu_header: PduHeader,
+        offset: u64,
+        file_data: &'file_data [u8],
+    ) -> Self {
+        Self::new(pdu_header, None, offset, file_data)
+    }
+
+    /// Generic constructor for a file data PDU.
+    pub fn new(
+        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 {
+            common: FdPduBase {
+                pdu_header,
+                segment_metadata,
+                offset,
+            },
+            file_data,
+        };
+        pdu.common.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        self.common
+            .calc_pdu_datafield_len(self.file_data.len() as u64)
+    }
+
+    /// Optional segment metadata.
+    #[inline]
+    pub fn segment_metadata(&self) -> Option<&SegmentMetadata<'_>> {
+        self.common.segment_metadata.as_ref()
+    }
+
+    /// PDU header.
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        self.common.pdu_header()
+    }
+
+    /// File data offset.
+    #[inline]
+    pub fn offset(&self) -> u64 {
+        self.common.offset
+    }
+
+    /// File data.
+    #[inline]
+    pub fn file_data(&self) -> &'file_data [u8] {
+        self.file_data
+    }
+
+    /// Read [Self] from the provided buffer.
+    pub fn from_bytes<'buf: 'seg_meta + 'file_data>(buf: &'buf [u8]) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let min_expected_len = current_idx + core::mem::size_of::<u32>();
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let mut segment_metadata = None;
+        if pdu_header.seg_metadata_flag == SegmentMetadataFlag::Present {
+            segment_metadata = Some(SegmentMetadata::from_bytes(&buf[current_idx..])?);
+            current_idx += segment_metadata.as_ref().unwrap().len_written();
+        }
+        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 {
+            common: FdPduBase {
+                pdu_header,
+                segment_metadata,
+                offset,
+            },
+            file_data: &buf[current_idx..full_len_without_crc],
+        })
+    }
+
+    /// Write [Self] to the provided buffer and returns the written size.
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        if buf.len() < self.len_written() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_written(),
+            }
+            .into());
+        }
+
+        let mut current_idx = self.common.write_common_fields_to_bytes(buf)?;
         buf[current_idx..current_idx + self.file_data.len()].copy_from_slice(self.file_data);
         current_idx += self.file_data.len();
         if self.crc_flag() == CrcFlag::WithCrc {
@@ -237,10 +300,194 @@ impl WritablePduPacket for FileDataPdu<'_, '_> {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
-        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    /// Length of the written PDU.
+    pub fn len_written(&self) -> usize {
+        self.common.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
+impl CfdpPdu for FileDataPdu<'_, '_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        &self.common.pdu_header
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
+    }
+}
+
+impl WritablePduPacket for FileDataPdu<'_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
+/// File Data PDU creator abstraction.
+///
+/// This special creator object allows to read into the file data buffer directly. This avoids
+/// the need of an additional buffer to create a file data PDU. This structure therefore
+/// does not implement the regular [WritablePduPacket] trait.
+///
+/// For more information, refer to CFDP chapter 5.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FileDataPduCreatorWithReservedDatafield<'seg_meta> {
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    common: FdPduBase<'seg_meta>,
+    file_data_len: u64,
+}
+
+impl<'seg_meta> FileDataPduCreatorWithReservedDatafield<'seg_meta> {
+    /// Constructor for a file data PDU including segment metadata.
+    pub fn new_with_seg_metadata(
+        pdu_header: PduHeader,
+        segment_metadata: SegmentMetadata<'seg_meta>,
+        offset: u64,
+        file_data_len: u64,
+    ) -> Self {
+        Self::new(pdu_header, Some(segment_metadata), offset, file_data_len)
+    }
+
+    /// Constructor for a file data PDU without segment metadata.
+    pub fn new_no_seg_metadata(pdu_header: PduHeader, offset: u64, file_data_len: u64) -> Self {
+        Self::new(pdu_header, None, offset, file_data_len)
+    }
+
+    /// Generic constructor.
+    pub fn new(
+        mut pdu_header: PduHeader,
+        segment_metadata: Option<SegmentMetadata<'seg_meta>>,
+        offset: u64,
+        file_data_len: u64,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileData;
+        if segment_metadata.is_some() {
+            pdu_header.seg_metadata_flag = SegmentMetadataFlag::Present;
+        }
+        let mut pdu = Self {
+            common: FdPduBase {
+                pdu_header,
+                segment_metadata,
+                offset,
+            },
+            file_data_len,
+        };
+        pdu.common.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        self.common.calc_pdu_datafield_len(self.file_data_len)
+    }
+
+    /// Length of the written PDU.
+    pub fn len_written(&self) -> usize {
+        self.common.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    /// This function performs a partial write by writing all data except the file data
+    /// and the CRC.
+    ///
+    /// It returns a [FileDataPduCreatorWithUnwrittenData] which provides a mutable slice to
+    /// the reserved file data field. The user can read file data into this field directly and
+    /// then finish the PDU creation using the [FileDataPduCreatorWithUnwrittenData::finish] call.
+    pub fn write_to_bytes_partially<'buf>(
+        &self,
+        buf: &'buf mut [u8],
+    ) -> Result<FileDataPduCreatorWithUnwrittenData<'buf>, PduError> {
+        if buf.len() < self.len_written() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_written(),
+            }
+            .into());
+        }
+        let mut current_idx = self.common.write_common_fields_to_bytes(buf)?;
+        let file_data_offset = current_idx as u64;
+        current_idx += self.file_data_len as usize;
+        if self.crc_flag() == CrcFlag::WithCrc {
+            current_idx += 2;
+        }
+        Ok(FileDataPduCreatorWithUnwrittenData {
+            write_buf: &mut buf[0..current_idx],
+            file_data_offset,
+            file_data_len: self.file_data_len,
+            needs_crc: self.crc_flag() == CrcFlag::WithCrc,
+        })
+    }
+}
+
+impl CfdpPdu for FileDataPduCreatorWithReservedDatafield<'_> {
+    fn pdu_header(&self) -> &PduHeader {
+        &self.common.pdu_header
+    }
+
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        None
+    }
+}
+
+/// This structure is created with [FileDataPduCreatorWithReservedDatafield::write_to_bytes_partially]
+/// and provides an API to read file data from the virtual filesystem into the file data PDU buffer
+/// directly.
+///
+/// This structure provides a mutable slice to the reserved file data field. The user can read
+/// file data into this field directly and then finish the PDU creation using the
+/// [FileDataPduCreatorWithUnwrittenData::finish] call.
+pub struct FileDataPduCreatorWithUnwrittenData<'buf> {
+    write_buf: &'buf mut [u8],
+    file_data_offset: u64,
+    file_data_len: u64,
+    needs_crc: bool,
+}
+
+impl FileDataPduCreatorWithUnwrittenData<'_> {
+    /// Mutable access to the file data field.
+    pub fn file_data_field_mut(&mut self) -> &mut [u8] {
+        &mut self.write_buf[self.file_data_offset as usize
+            ..self.file_data_offset as usize + self.file_data_len as usize]
+    }
+
+    /// This functio needs to be called to add a CRC to the file data PDU where applicable.
+    ///
+    /// It returns the full written size of the PDU.
+    pub fn finish(self) -> usize {
+        if self.needs_crc {
+            add_pdu_crc(
+                self.write_buf,
+                self.file_data_offset as usize + self.file_data_len as usize,
+            );
+        }
+        self.write_buf.len()
+    }
+}
+
+/// This function can be used to calculate the maximum allowed file segment size for
+/// a given maximum packet length and the segment metadata if there is any.
+pub fn calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(
+    pdu_header: &PduHeader,
+    max_packet_len: usize,
+    segment_metadata: Option<&SegmentMetadata>,
+) -> usize {
+    let mut subtract = pdu_header.header_len();
+    if let Some(segment_metadata) = segment_metadata {
+        subtract += 1 + segment_metadata.metadata().unwrap().len();
+    }
+    if pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
+        subtract += 8;
+    } else {
+        subtract += 4;
+    }
+    if pdu_header.common_pdu_conf().crc_flag == CrcFlag::WithCrc {
+        subtract += 2;
+    }
+    max_packet_len.saturating_sub(subtract)
+}
 
 #[cfg(test)]
 mod tests {
@@ -263,7 +510,7 @@ mod tests {
         assert!(fd_pdu.segment_metadata().is_none());
         assert_eq!(
             fd_pdu.len_written(),
-            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+            fd_pdu.pdu_header().header_len() + core::mem::size_of::<u32>() + 4
         );
 
         assert_eq!(fd_pdu.crc_flag(), CrcFlag::NoCrc);
@@ -290,11 +537,11 @@ mod tests {
         let written = res.unwrap();
         assert_eq!(
             written,
-            fd_pdu.pdu_header.header_len() + core::mem::size_of::<u32>() + 4
+            fd_pdu.pdu_header().header_len() + core::mem::size_of::<u32>() + 4
         );
-        let mut current_idx = fd_pdu.pdu_header.header_len();
+        let mut current_idx = fd_pdu.pdu_header().header_len();
         let file_size = u32::from_be_bytes(
-            buf[fd_pdu.pdu_header.header_len()..fd_pdu.pdu_header.header_len() + 4]
+            buf[fd_pdu.pdu_header().header_len()..fd_pdu.pdu_header().header_len() + 4]
                 .try_into()
                 .unwrap(),
         );
@@ -353,7 +600,7 @@ mod tests {
         buf[written - 1] -= 1;
         let crc: u16 = ((buf[written - 2] as u16) << 8) | buf[written - 1] as u16;
         let error = FileDataPdu::from_bytes(&buf).unwrap_err();
-        if let PduError::ChecksumError(e) = error {
+        if let PduError::Checksum(e) = error {
             assert_eq!(e, crc);
         } else {
             panic!("expected crc error");
@@ -380,7 +627,7 @@ mod tests {
         assert_eq!(*fd_pdu.segment_metadata().unwrap(), segment_meta);
         assert_eq!(
             fd_pdu.len_written(),
-            fd_pdu.pdu_header.header_len()
+            fd_pdu.pdu_header().header_len()
                 + 1
                 + seg_metadata.len()
                 + core::mem::size_of::<u32>()
@@ -390,7 +637,7 @@ mod tests {
         fd_pdu
             .write_to_bytes(&mut buf)
             .expect("writing FD PDU failed");
-        let mut current_idx = fd_pdu.pdu_header.header_len();
+        let mut current_idx = fd_pdu.pdu_header().header_len();
         assert_eq!(
             RecordContinuationState::try_from((buf[current_idx] >> 6) & 0b11).unwrap(),
             RecordContinuationState::StartAndEnd
@@ -482,4 +729,142 @@ mod tests {
         let output_converted_back: FileDataPdu = from_bytes(&output).unwrap();
         assert_eq!(output_converted_back, fd_pdu);
     }
+
+    #[test]
+    fn test_fd_pdu_creator_with_reserved_field_no_crc() {
+        let common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let test_str = "hello world!";
+        let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
+            pdu_header,
+            10,
+            test_str.len() as u64,
+        );
+        let mut write_buf: [u8; 64] = [0; 64];
+        let mut pdu_unwritten = fd_pdu
+            .write_to_bytes_partially(&mut write_buf)
+            .expect("partial write failed");
+        pdu_unwritten
+            .file_data_field_mut()
+            .copy_from_slice(test_str.as_bytes());
+        pdu_unwritten.finish();
+
+        let pdu_reader = FileDataPdu::from_bytes(&write_buf).expect("reading file data PDU failed");
+        assert_eq!(
+            core::str::from_utf8(pdu_reader.file_data()).expect("reading utf8 string failed"),
+            "hello world!"
+        );
+    }
+
+    #[test]
+    fn test_fd_pdu_creator_with_reserved_field_with_crc() {
+        let mut common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        common_conf.crc_flag = true.into();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let test_str = "hello world!";
+        let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
+            pdu_header,
+            10,
+            test_str.len() as u64,
+        );
+        let mut write_buf: [u8; 64] = [0; 64];
+        let mut pdu_unwritten = fd_pdu
+            .write_to_bytes_partially(&mut write_buf)
+            .expect("partial write failed");
+        pdu_unwritten
+            .file_data_field_mut()
+            .copy_from_slice(test_str.as_bytes());
+        pdu_unwritten.finish();
+
+        let pdu_reader = FileDataPdu::from_bytes(&write_buf).expect("reading file data PDU failed");
+        assert_eq!(
+            core::str::from_utf8(pdu_reader.file_data()).expect("reading utf8 string failed"),
+            "hello world!"
+        );
+    }
+
+    #[test]
+    fn test_fd_pdu_creator_with_reserved_field_with_crc_without_finish_fails() {
+        let mut common_conf =
+            CommonPduConfig::new_with_byte_fields(TEST_SRC_ID, TEST_DEST_ID, TEST_SEQ_NUM).unwrap();
+        common_conf.crc_flag = true.into();
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        let test_str = "hello world!";
+        let fd_pdu = FileDataPduCreatorWithReservedDatafield::new_no_seg_metadata(
+            pdu_header,
+            10,
+            test_str.len() as u64,
+        );
+        let mut write_buf: [u8; 64] = [0; 64];
+        let mut pdu_unwritten = fd_pdu
+            .write_to_bytes_partially(&mut write_buf)
+            .expect("partial write failed");
+        pdu_unwritten
+            .file_data_field_mut()
+            .copy_from_slice(test_str.as_bytes());
+
+        let pdu_reader_error = FileDataPdu::from_bytes(&write_buf);
+        assert!(pdu_reader_error.is_err());
+        let error = pdu_reader_error.unwrap_err();
+        match error {
+            PduError::Checksum(_) => (),
+            _ => {
+                panic!("unexpected PDU error {}", error)
+            }
+        }
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_0() {
+        let pdu_header = PduHeader::new_for_file_data_default(CommonPduConfig::default(), 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
+            53
+        );
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_1() {
+        let common_conf = CommonPduConfig {
+            crc_flag: CrcFlag::WithCrc,
+            ..Default::default()
+        };
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
+            51
+        );
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_2() {
+        let common_conf = CommonPduConfig {
+            file_flag: LargeFileFlag::Large,
+            ..Default::default()
+        };
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 64, None),
+            49
+        );
+    }
+
+    #[test]
+    fn test_max_file_seg_calculator_saturating_sub() {
+        let common_conf = CommonPduConfig {
+            file_flag: LargeFileFlag::Large,
+            ..Default::default()
+        };
+        let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 15, None),
+            0
+        );
+        assert_eq!(
+            calculate_max_file_seg_len_for_max_packet_len_and_pdu_header(&pdu_header, 14, None),
+            0
+        );
+    }
 }

src/cfdp/pdu/finished.rs

@@ -1,34 +1,44 @@
+//! # Finished PDU packet implementation.
 use crate::cfdp::pdu::{
     add_pdu_crc, generic_length_checks_pdu_deserialization, FileDirectiveType, PduError, PduHeader,
 };
 use crate::cfdp::tlv::{
     EntityIdTlv, FilestoreResponseTlv, GenericTlv, Tlv, TlvType, TlvTypeField, WritableTlv,
 };
-use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType, TlvLvError};
+use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType};
 use crate::ByteConversionError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
-use super::{CfdpPdu, WritablePduPacket};
+use super::tlv::ReadableTlv;
+use super::{CfdpPdu, InvalidTlvTypeFieldError, WritablePduPacket};
 
+/// Delivery code enumeration.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum DeliveryCode {
+    /// Completed delivery.
     Complete = 0,
+    /// Incomplete delivery.
     Incomplete = 1,
 }
 
+/// File status enumeration.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum FileStatus {
+    /// File was discarded deliberately.
     DiscardDeliberately = 0b00,
+    /// File was rejected by the filestore.
     DiscardedFsRejection = 0b01,
+    /// File was retained (but not necesarilly complete).
     Retained = 0b10,
+    /// Unreported file status.
     Unreported = 0b11,
 }
 
@@ -49,12 +59,12 @@ pub struct FinishedPduCreator<'fs_responses> {
 
 impl<'fs_responses> FinishedPduCreator<'fs_responses> {
     /// Default finished PDU: No error (no fault location field) and no filestore responses.
-    pub fn new_default(
+    pub fn new_no_error(
         pdu_header: PduHeader,
         delivery_code: DeliveryCode,
         file_status: FileStatus,
     ) -> Self {
-        Self::new_generic(
+        Self::new(
             pdu_header,
             ConditionCode::NoError,
             delivery_code,
@@ -64,6 +74,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         )
     }
 
+    /// Constructor where the fault location is provided.
     pub fn new_with_error(
         pdu_header: PduHeader,
         condition_code: ConditionCode,
@@ -71,7 +82,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         file_status: FileStatus,
         fault_location: EntityIdTlv,
     ) -> Self {
-        Self::new_generic(
+        Self::new(
             pdu_header,
             condition_code,
             delivery_code,
@@ -81,7 +92,8 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         )
     }
 
-    pub fn new_generic(
+    /// Generic constructor.
+    pub fn new(
         mut pdu_header: PduHeader,
         condition_code: ConditionCode,
         delivery_code: DeliveryCode,
@@ -108,23 +120,38 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         finished_pdu
     }
 
+    /// PDU header.
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    /// Condition code.
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    /// Delivery code.
+    #[inline]
     pub fn delivery_code(&self) -> DeliveryCode {
         self.delivery_code
     }
 
+    /// File status.
+    #[inline]
     pub fn file_status(&self) -> FileStatus {
         self.file_status
     }
 
-    // If there are no filestore responses, an empty slice will be returned.
+    /// Filestore responses as a slice.
+    #[inline]
     pub fn filestore_responses(&self) -> &[FilestoreResponseTlv<'_, '_, '_>] {
         self.fs_responses
     }
 
+    /// Optional fault location [EntityIdTlv].
+    #[inline]
     pub fn fault_location(&self) -> Option<EntityIdTlv> {
         self.fault_location
     }
@@ -142,20 +169,9 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         }
         datafield_len
     }
-}
 
-impl CfdpPdu for FinishedPduCreator<'_> {
-    fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
-    }
-
-    fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::FinishedPdu)
-    }
-}
-
-impl WritablePduPacket for FinishedPduCreator<'_> {
-    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+    /// Write [Self] to the provided buffer and returns the written size.
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
         let expected_len = self.len_written();
         if buf.len() < expected_len {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -166,7 +182,7 @@ impl WritablePduPacket for FinishedPduCreator<'_> {
         }
 
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
-        buf[current_idx] = FileDirectiveType::FinishedPdu as u8;
+        buf[current_idx] = FileDirectiveType::Finished as u8;
         current_idx += 1;
         buf[current_idx] = ((self.condition_code as u8) << 4)
             | ((self.delivery_code as u8) << 2)
@@ -184,11 +200,34 @@ impl WritablePduPacket for FinishedPduCreator<'_> {
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    /// Length of the written PDU in bytes.
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for FinishedPduCreator<'_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::Finished)
+    }
+}
+
+impl WritablePduPacket for FinishedPduCreator<'_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 /// Helper structure to loop through all filestore responses of a read Finished PDU. It should be
 /// noted that iterators in Rust are not fallible, but the TLV creation can fail, for example if
 /// the raw TLV data is invalid for some reason. In that case, the iterator will yield [None]
@@ -220,6 +259,7 @@ impl<'buf> Iterator for FilestoreResponseIterator<'buf> {
     }
 }
 
+/// Fnished PDU reader structure.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -247,13 +287,13 @@ impl<'buf> FinishedPduReader<'buf> {
         let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
             PduError::InvalidDirectiveType {
                 found: buf[current_idx],
-                expected: Some(FileDirectiveType::FinishedPdu),
+                expected: Some(FileDirectiveType::Finished),
             }
         })?;
-        if directive_type != FileDirectiveType::FinishedPdu {
+        if directive_type != FileDirectiveType::Finished {
             return Err(PduError::WrongDirectiveType {
                 found: directive_type,
-                expected: FileDirectiveType::FinishedPdu,
+                expected: FileDirectiveType::Finished,
             });
         }
         current_idx += 1;
@@ -275,10 +315,14 @@ impl<'buf> FinishedPduReader<'buf> {
         })
     }
 
+    /// Raw filestore responses.
+    #[inline]
     pub fn fs_responses_raw(&self) -> &[u8] {
         self.fs_responses_raw
     }
 
+    /// Iterator over the filestore responses.
+    #[inline]
     pub fn fs_responses_iter(&self) -> FilestoreResponseIterator<'_> {
         FilestoreResponseIterator {
             responses_buf: self.fs_responses_raw,
@@ -286,22 +330,36 @@ impl<'buf> FinishedPduReader<'buf> {
         }
     }
 
+    /// Condition code.
+    #[inline]
     pub fn condition_code(&self) -> ConditionCode {
         self.condition_code
     }
 
+    /// Delivery code.
+    #[inline]
     pub fn delivery_code(&self) -> DeliveryCode {
         self.delivery_code
     }
 
+    /// File status.
+    #[inline]
     pub fn file_status(&self) -> FileStatus {
         self.file_status
     }
 
+    /// Optional fault location [EntityIdTlv].
+    #[inline]
     pub fn fault_location(&self) -> Option<EntityIdTlv> {
         self.fault_location
     }
 
+    /// PDU header.
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
     fn parse_tlv_fields(
         mut current_idx: usize,
         full_len_without_crc: usize,
@@ -331,22 +389,26 @@ impl<'buf> FinishedPduReader<'buf> {
                         // last TLV, everything else would break the whole handling of the packet
                         // TLVs.
                         if current_idx != full_len_without_crc {
-                            return Err(PduError::FormatError);
+                            return Err(PduError::Format);
                         }
                     } else {
-                        return Err(TlvLvError::InvalidTlvTypeField {
-                            found: tlv_type.into(),
-                            expected: Some(TlvType::FilestoreResponse.into()),
-                        }
-                        .into());
+                        return Err(PduError::TlvLv(
+                            InvalidTlvTypeFieldError {
+                                found: tlv_type.into(),
+                                expected: Some(TlvType::FilestoreResponse.into()),
+                            }
+                            .into(),
+                        ));
                     }
                 }
                 TlvTypeField::Custom(raw) => {
-                    return Err(TlvLvError::InvalidTlvTypeField {
-                        found: raw,
-                        expected: None,
-                    }
-                    .into());
+                    return Err(PduError::TlvLv(
+                        InvalidTlvTypeFieldError {
+                            found: raw,
+                            expected: None,
+                        }
+                        .into(),
+                    ));
                 }
             }
         }
@@ -355,12 +417,14 @@ impl<'buf> FinishedPduReader<'buf> {
 }
 
 impl CfdpPdu for FinishedPduReader<'_> {
+    #[inline]
     fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
+        self.pdu_header()
     }
 
+    #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::FinishedPdu)
+        Some(FileDirectiveType::Finished)
     }
 }
 
@@ -401,8 +465,8 @@ mod tests {
         delivery_code: DeliveryCode,
         file_status: FileStatus,
     ) -> FinishedPduCreator<'static> {
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
-        FinishedPduCreator::new_default(pdu_header, delivery_code, file_status)
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_conf(crc_flag, fss), 0);
+        FinishedPduCreator::new_no_error(pdu_header, delivery_code, file_status)
     }
 
     #[test]
@@ -429,7 +493,7 @@ mod tests {
         assert_eq!(finished_pdu.pdu_type(), PduType::FileDirective);
         assert_eq!(
             finished_pdu.file_directive_type(),
-            Some(FileDirectiveType::FinishedPdu)
+            Some(FileDirectiveType::Finished)
         );
         assert_eq!(
             finished_pdu.transmission_mode(),
@@ -461,7 +525,7 @@ mod tests {
         );
         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);
+        assert_eq!(buf[current_idx], FileDirectiveType::Finished as u8);
         current_idx += 1;
         assert_eq!(
             (buf[current_idx] >> 4) & 0b1111,
@@ -563,7 +627,7 @@ mod tests {
         buf[written - 1] -= 1;
         let crc: u16 = ((buf[written - 2] as u16) << 8) as u16 | buf[written - 1] as u16;
         let error = FinishedPduReader::new(&buf).unwrap_err();
-        if let PduError::ChecksumError(e) = error {
+        if let PduError::Checksum(e) = error {
             assert_eq!(e, crc);
         } else {
             panic!("expected crc error");
@@ -572,8 +636,10 @@ mod tests {
 
     #[test]
     fn test_with_fault_location() {
-        let pdu_header =
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+        let pdu_header = PduHeader::new_for_file_directive(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+        );
         let finished_pdu = FinishedPduCreator::new_with_error(
             pdu_header,
             ConditionCode::NakLimitReached,
@@ -585,7 +651,7 @@ mod tests {
         assert_eq!(finished_pdu_vec.len(), 12);
         assert_eq!(finished_pdu_vec[9], TlvType::EntityId.into());
         assert_eq!(finished_pdu_vec[10], 1);
-        assert_eq!(finished_pdu_vec[11], TEST_DEST_ID.value_typed());
+        assert_eq!(finished_pdu_vec[11], TEST_DEST_ID.value());
         assert_eq!(
             finished_pdu.fault_location().unwrap().entity_id(),
             &TEST_DEST_ID.into()
@@ -594,8 +660,10 @@ mod tests {
 
     #[test]
     fn test_deserialization_with_fault_location() {
-        let pdu_header =
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
+        let pdu_header = PduHeader::new_for_file_directive(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+        );
         let entity_id_tlv = EntityIdTlv::new(TEST_DEST_ID.into());
         let finished_pdu = FinishedPduCreator::new_with_error(
             pdu_header,
@@ -630,9 +698,11 @@ mod tests {
         .unwrap();
         let fs_responses = &[fs_response_0, fs_response_1];
 
-        let pdu_header =
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
-        let finished_pdu = FinishedPduCreator::new_generic(
+        let pdu_header = PduHeader::new_for_file_directive(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+        );
+        let finished_pdu = FinishedPduCreator::new(
             pdu_header,
             ConditionCode::NakLimitReached,
             DeliveryCode::Incomplete,
@@ -665,9 +735,11 @@ mod tests {
         .unwrap();
         let fs_responses = &[fs_response_0, fs_response_1];
 
-        let pdu_header =
-            PduHeader::new_no_file_data(common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal), 0);
-        let finished_pdu = FinishedPduCreator::new_generic(
+        let pdu_header = PduHeader::new_for_file_directive(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+        );
+        let finished_pdu = FinishedPduCreator::new(
             pdu_header,
             ConditionCode::NakLimitReached,
             DeliveryCode::Incomplete,

src/cfdp/pdu/metadata.rs

@@ -1,3 +1,6 @@
+//! # Metadata PDU packet implementation.
+#[cfg(feature = "alloc")]
+use super::tlv::TlvOwned;
 use crate::cfdp::lv::Lv;
 use crate::cfdp::pdu::{
     add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
@@ -11,18 +14,24 @@ use alloc::vec::Vec;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+use super::tlv::ReadableTlv;
 use super::{CfdpPdu, WritablePduPacket};
 
+/// Generic metadata parameters.
 #[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct MetadataGenericParams {
+    /// Closure requested flag.
     pub closure_requested: bool,
+    /// Checksum type.
     pub checksum_type: ChecksumType,
+    /// File size.
     pub file_size: u64,
 }
 
 impl MetadataGenericParams {
+    /// Constructor.
     pub fn new(closure_requested: bool, checksum_type: ChecksumType, file_size: u64) -> Self {
         Self {
             closure_requested,
@@ -32,6 +41,7 @@ impl MetadataGenericParams {
     }
 }
 
+/// Build the metadata options from a slice of [Tlv]s
 pub fn build_metadata_opts_from_slice(
     buf: &mut [u8],
     tlvs: &[Tlv],
@@ -43,6 +53,7 @@ pub fn build_metadata_opts_from_slice(
     Ok(written)
 }
 
+/// Build the metadata options from a vector of [Tlv]s
 #[cfg(feature = "alloc")]
 pub fn build_metadata_opts_from_vec(
     buf: &mut [u8],
@@ -51,21 +62,31 @@ pub fn build_metadata_opts_from_vec(
     build_metadata_opts_from_slice(buf, tlvs.as_slice())
 }
 
+/// Build the metadata options from a slice of [TlvOwned]s
+#[cfg(feature = "alloc")]
+pub fn build_metadata_opts_from_owned_slice(tlvs: &[TlvOwned]) -> Vec<u8> {
+    let mut sum_vec = Vec::new();
+    for tlv in tlvs {
+        sum_vec.extend(tlv.to_vec());
+    }
+    sum_vec
+}
+
 /// Metadata PDU creator abstraction.
 ///
 /// This abstraction exposes a specialized API for creating metadata PDUs as specified in
 /// CFDP chapter 5.2.5.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct MetadataPduCreator<'src_name, 'dest_name, 'opts> {
     pdu_header: PduHeader,
     metadata_params: MetadataGenericParams,
     src_file_name: Lv<'src_name>,
     dest_file_name: Lv<'dest_name>,
-    options: &'opts [Tlv<'opts>],
+    options: &'opts [u8],
 }
 
 impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'opts> {
+    /// Constructor for a metadata PDU without options.
     pub fn new_no_opts(
         pdu_header: PduHeader,
         metadata_params: MetadataGenericParams,
@@ -81,12 +102,13 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         )
     }
 
+    /// Constructor for a metadata PDU with options.
     pub fn new_with_opts(
         pdu_header: PduHeader,
         metadata_params: MetadataGenericParams,
         src_file_name: Lv<'src_name>,
         dest_file_name: Lv<'dest_name>,
-        options: &'opts [Tlv<'opts>],
+        options: &'opts [u8],
     ) -> Self {
         Self::new(
             pdu_header,
@@ -97,12 +119,13 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         )
     }
 
+    /// Generic constructor for a metadata PDU.
     pub fn new(
         mut pdu_header: PduHeader,
         metadata_params: MetadataGenericParams,
         src_file_name: Lv<'src_name>,
         dest_file_name: Lv<'dest_name>,
-        options: &'opts [Tlv<'opts>],
+        options: &'opts [u8],
     ) -> Self {
         pdu_header.pdu_type = PduType::FileDirective;
         pdu_header.pdu_conf.direction = Direction::TowardsReceiver;
@@ -117,22 +140,45 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         pdu
     }
 
+    /// Metadata generic parameters.
+    #[inline]
     pub fn metadata_params(&self) -> &MetadataGenericParams {
         &self.metadata_params
     }
 
+    /// Source file name as a [Lv].
+    #[inline]
     pub fn src_file_name(&self) -> Lv<'src_name> {
         self.src_file_name
     }
 
+    /// Destination file name as a [Lv].
+    #[inline]
     pub fn dest_file_name(&self) -> Lv<'dest_name> {
         self.dest_file_name
     }
 
-    pub fn options(&self) -> &'opts [Tlv<'opts>] {
+    /// PDU header.
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    /// Raw options.
+    #[inline]
+    pub fn options(&self) -> &'opts [u8] {
         self.options
     }
 
+    /// Yield an iterator which can be used to loop through all options. Returns [None] if the
+    /// options field is empty.
+    pub fn options_iter(&self) -> OptionsIter<'_> {
+        OptionsIter {
+            opt_buf: self.options,
+            current_idx: 0,
+        }
+    }
+
     fn calc_pdu_datafield_len(&self) -> usize {
         // One directve type octet and one byte of the directive parameter field.
         let mut len = 2;
@@ -143,28 +189,15 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         }
         len += self.src_file_name.len_full();
         len += self.dest_file_name.len_full();
-        for tlv in self.options() {
-            len += tlv.len_full()
-        }
+        len += self.options().len();
         if self.crc_flag() == CrcFlag::WithCrc {
             len += 2;
         }
         len
     }
-}
 
-impl CfdpPdu for MetadataPduCreator<'_, '_, '_> {
-    fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
-    }
-
-    fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::MetadataPdu)
-    }
-}
-
-impl WritablePduPacket for MetadataPduCreator<'_, '_, '_> {
-    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+    /// Write [Self] to the provided buffer and returns the written size.
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
         let expected_len = self.len_written();
         if buf.len() < expected_len {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -175,7 +208,7 @@ impl WritablePduPacket for MetadataPduCreator<'_, '_, '_> {
         }
 
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
-        buf[current_idx] = FileDirectiveType::MetadataPdu as u8;
+        buf[current_idx] = FileDirectiveType::Metadata as u8;
         current_idx += 1;
         buf[current_idx] = ((self.metadata_params.closure_requested as u8) << 6)
             | (self.metadata_params.checksum_type as u8);
@@ -191,21 +224,42 @@ impl WritablePduPacket for MetadataPduCreator<'_, '_, '_> {
         current_idx += self
             .dest_file_name
             .write_to_be_bytes(&mut buf[current_idx..])?;
-        for opt in self.options() {
-            opt.write_to_bytes(&mut buf[current_idx..current_idx + opt.len_full()])?;
-            current_idx += opt.len_full();
-        }
+        buf[current_idx..current_idx + self.options.len()].copy_from_slice(self.options);
+        current_idx += self.options.len();
         if self.crc_flag() == CrcFlag::WithCrc {
             current_idx = add_pdu_crc(buf, current_idx);
         }
         Ok(current_idx)
     }
 
-    fn len_written(&self) -> usize {
+    /// Length of the written PDU in bytes.
+    pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
 }
 
+impl CfdpPdu for MetadataPduCreator<'_, '_, '_> {
+    #[inline]
+    fn pdu_header(&self) -> &PduHeader {
+        self.pdu_header()
+    }
+
+    #[inline]
+    fn file_directive_type(&self) -> Option<FileDirectiveType> {
+        Some(FileDirectiveType::Metadata)
+    }
+}
+
+impl WritablePduPacket for MetadataPduCreator<'_, '_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        self.write_to_bytes(buf)
+    }
+
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 /// Helper structure to loop through all options of a metadata PDU. It should be noted that
 /// iterators in Rust are not fallible, but the TLV creation can fail, for example if the raw TLV
 /// data is invalid for some reason. In that case, the iterator will yield [None] because there
@@ -255,10 +309,12 @@ pub struct MetadataPduReader<'buf> {
 }
 
 impl<'raw> MetadataPduReader<'raw> {
+    /// Constructor from raw bytes.
     pub fn new(buf: &'raw [u8]) -> Result<Self, PduError> {
         Self::from_bytes(buf)
     }
 
+    /// Constructor from raw bytes.
     pub fn from_bytes(buf: &'raw [u8]) -> Result<Self, PduError> {
         let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
         let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
@@ -272,13 +328,13 @@ impl<'raw> MetadataPduReader<'raw> {
         let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
             PduError::InvalidDirectiveType {
                 found: buf[current_idx],
-                expected: Some(FileDirectiveType::MetadataPdu),
+                expected: Some(FileDirectiveType::Metadata),
             }
         })?;
-        if directive_type != FileDirectiveType::MetadataPdu {
+        if directive_type != FileDirectiveType::Metadata {
             return Err(PduError::WrongDirectiveType {
                 found: directive_type,
-                expected: FileDirectiveType::MetadataPdu,
+                expected: FileDirectiveType::Metadata,
             });
         }
         current_idx += 1;
@@ -314,35 +370,50 @@ impl<'raw> MetadataPduReader<'raw> {
         })
     }
 
+    /// PDU header.
+    #[inline]
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    /// Raw options.
+    #[inline]
     pub fn options(&self) -> &'raw [u8] {
         self.options
     }
 
+    /// Generic metadata parameters.
+    #[inline]
     pub fn metadata_params(&self) -> &MetadataGenericParams {
         &self.metadata_params
     }
 
-    pub fn src_file_name(&self) -> Lv {
+    /// Source file name as a [Lv].
+    #[inline]
+    pub fn src_file_name(&self) -> Lv<'_> {
         self.src_file_name
     }
 
-    pub fn dest_file_name(&self) -> Lv {
+    /// Destination file name as a [Lv].
+    #[inline]
+    pub fn dest_file_name(&self) -> Lv<'_> {
         self.dest_file_name
     }
 }
 
 impl CfdpPdu for MetadataPduReader<'_> {
+    #[inline]
     fn pdu_header(&self) -> &PduHeader {
-        &self.pdu_header
+        self.pdu_header()
     }
 
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::MetadataPdu)
+        Some(FileDirectiveType::Metadata)
     }
 }
 
 #[cfg(test)]
-pub mod tests {
+mod tests {
     use alloc::string::ToString;
 
     use crate::cfdp::lv::Lv;
@@ -355,7 +426,7 @@ pub mod tests {
     };
     use crate::cfdp::pdu::{CfdpPdu, PduError, WritablePduPacket};
     use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
-    use crate::cfdp::tlv::{Tlv, TlvType};
+    use crate::cfdp::tlv::{ReadableTlv, Tlv, TlvOwned, TlvType, WritableTlv};
     use crate::cfdp::{
         ChecksumType, CrcFlag, Direction, LargeFileFlag, PduType, SegmentMetadataFlag,
         SegmentationControl, TransmissionMode,
@@ -365,18 +436,18 @@ pub mod tests {
     const SRC_FILENAME: &str = "hello-world.txt";
     const DEST_FILENAME: &str = "hello-world2.txt";
 
-    fn generic_metadata_pdu<'opts>(
+    fn generic_metadata_pdu(
         crc_flag: CrcFlag,
         checksum_type: ChecksumType,
         closure_requested: bool,
         fss: LargeFileFlag,
-        opts: &'opts [Tlv],
+        opts: &[u8],
     ) -> (
         Lv<'static>,
         Lv<'static>,
-        MetadataPduCreator<'static, 'static, 'opts>,
+        MetadataPduCreator<'static, 'static, '_>,
     ) {
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_conf(crc_flag, fss), 0);
         let metadata_params = MetadataGenericParams::new(closure_requested, checksum_type, 0x1010);
         let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
         let dest_filename =
@@ -425,7 +496,7 @@ pub mod tests {
         );
         assert_eq!(
             metadata_pdu.file_directive_type(),
-            Some(FileDirectiveType::MetadataPdu)
+            Some(FileDirectiveType::Metadata)
         );
         assert_eq!(
             metadata_pdu.transmission_mode(),
@@ -456,7 +527,7 @@ pub mod tests {
                 + expected_src_filename.len_full()
                 + expected_dest_filename.len_full()
         );
-        assert_eq!(buf[7], FileDirectiveType::MetadataPdu as u8);
+        assert_eq!(buf[7], FileDirectiveType::Metadata as u8);
         assert_eq!(buf[8] >> 6, closure_requested as u8);
         assert_eq!(buf[8] & 0b1111, checksum_type as u8);
         assert_eq!(u32::from_be_bytes(buf[9..13].try_into().unwrap()), 0x1010);
@@ -544,9 +615,9 @@ pub mod tests {
         assert_eq!(written.metadata_params(), read.metadata_params());
         assert_eq!(written.src_file_name(), read.src_file_name());
         assert_eq!(written.dest_file_name(), read.dest_file_name());
-        let opts = written.options();
-        for (tlv_written, tlv_read) in opts.iter().zip(read.options_iter().unwrap()) {
-            assert_eq!(tlv_written, &tlv_read);
+        let opts = written.options_iter();
+        for (tlv_written, tlv_read) in opts.zip(read.options_iter().unwrap()) {
+            assert_eq!(&tlv_written, &tlv_read);
         }
     }
 
@@ -661,14 +732,14 @@ pub mod tests {
         let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
         let msg_to_user: [u8; 4] = [1, 2, 3, 4];
         let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
-        let tlv_vec = vec![tlv1, tlv2];
-        let opts_len = tlv1.len_full() + tlv2.len_full();
+        let mut tlv_buf: [u8; 64] = [0; 64];
+        let opts_len = build_metadata_opts_from_slice(&mut tlv_buf, &[tlv1, tlv2]).unwrap();
         let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
             CrcFlag::NoCrc,
             ChecksumType::Crc32,
             false,
             LargeFileFlag::Normal,
-            &tlv_vec,
+            &tlv_buf[0..opts_len],
         );
         let mut buf: [u8; 128] = [0; 128];
         let write_res = metadata_pdu.write_to_bytes(&mut buf);
@@ -691,7 +762,55 @@ pub mod tests {
         let opts_iter = opts_iter.unwrap();
         let mut accumulated_len = 0;
         for (idx, opt) in opts_iter.enumerate() {
-            assert_eq!(tlv_vec[idx], opt);
+            if idx == 0 {
+                assert_eq!(tlv1, opt);
+            } else if idx == 1 {
+                assert_eq!(tlv2, opt);
+            }
+            accumulated_len += opt.len_full();
+        }
+        assert_eq!(accumulated_len, pdu_read_back.options().len());
+    }
+    #[test]
+    fn test_with_owned_opts() {
+        let tlv1 = TlvOwned::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = TlvOwned::new(TlvType::MsgToUser, &msg_to_user);
+        let mut all_tlvs = tlv1.to_vec();
+        all_tlvs.extend(tlv2.to_vec());
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            ChecksumType::Crc32,
+            false,
+            LargeFileFlag::Normal,
+            &all_tlvs,
+        );
+        let mut buf: [u8; 128] = [0; 128];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + all_tlvs.len()
+        );
+        let pdu_read_back = MetadataPduReader::from_bytes(&buf).unwrap();
+        compare_read_pdu_to_written_pdu(&metadata_pdu, &pdu_read_back);
+        let opts_iter = pdu_read_back.options_iter();
+        assert!(opts_iter.is_some());
+        let opts_iter = opts_iter.unwrap();
+        let mut accumulated_len = 0;
+        for (idx, opt) in opts_iter.enumerate() {
+            if idx == 0 {
+                assert_eq!(tlv1, opt);
+            } else if idx == 1 {
+                assert_eq!(tlv2, opt);
+            }
             accumulated_len += opt.len_full();
         }
         assert_eq!(accumulated_len, pdu_read_back.options().len());
@@ -713,10 +832,10 @@ pub mod tests {
         let error = metadata_error.unwrap_err();
         if let PduError::InvalidDirectiveType { found, expected } = error {
             assert_eq!(found, 0xff);
-            assert_eq!(expected, Some(FileDirectiveType::MetadataPdu));
+            assert_eq!(expected, Some(FileDirectiveType::Metadata));
             assert_eq!(
                 error.to_string(),
-                "invalid directive type value 255, expected Some(MetadataPdu)"
+                "invalid directive type, found 255, expected Some(Metadata)"
             );
         } else {
             panic!("Expected InvalidDirectiveType error, got {:?}", error);
@@ -733,16 +852,16 @@ pub mod tests {
             &[],
         );
         let mut metadata_vec = metadata_pdu.to_vec().unwrap();
-        metadata_vec[7] = FileDirectiveType::EofPdu as u8;
+        metadata_vec[7] = FileDirectiveType::Eof as u8;
         let metadata_error = MetadataPduReader::from_bytes(&metadata_vec);
         assert!(metadata_error.is_err());
         let error = metadata_error.unwrap_err();
         if let PduError::WrongDirectiveType { found, expected } = error {
-            assert_eq!(found, FileDirectiveType::EofPdu);
-            assert_eq!(expected, FileDirectiveType::MetadataPdu);
+            assert_eq!(found, FileDirectiveType::Eof);
+            assert_eq!(expected, FileDirectiveType::Metadata);
             assert_eq!(
                 error.to_string(),
-                "found directive type EofPdu, expected MetadataPdu"
+                "wrong directive type, found Eof, expected Metadata"
             );
         } else {
             panic!("Expected InvalidDirectiveType error, got {:?}", error);

src/cfdp/pdu/mod.rs

@@ -1,13 +1,12 @@
 //! CFDP Packet Data Unit (PDU) support.
+use crate::cfdp::pdu::ack::InvalidAckedDirectiveCodeError;
+use crate::cfdp::pdu::nak::InvalidStartOrEndOfScopeError;
 use crate::cfdp::*;
+use crate::crc::CRC_CCITT_FALSE;
 use crate::util::{UnsignedByteField, UnsignedByteFieldU8, UnsignedEnum};
 use crate::ByteConversionError;
-use crate::CRC_CCITT_FALSE;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
-use core::fmt::{Display, Formatter};
-#[cfg(feature = "std")]
-use std::error::Error;
 
 pub mod ack;
 pub mod eof;
@@ -16,156 +15,115 @@ pub mod finished;
 pub mod metadata;
 pub mod nak;
 
+/// File directive type.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum FileDirectiveType {
-    EofPdu = 0x04,
-    FinishedPdu = 0x05,
-    AckPdu = 0x06,
-    MetadataPdu = 0x07,
-    NakPdu = 0x08,
-    PromptPdu = 0x09,
-    KeepAlivePdu = 0x0c,
+    /// EOF.
+    Eof = 0x04,
+    /// Finished.
+    Finished = 0x05,
+    /// ACK.
+    Ack = 0x06,
+    /// Metadata.
+    Metadata = 0x07,
+    /// NAK.
+    Nak = 0x08,
+    /// Prompt.
+    Prompt = 0x09,
+    /// Keep Alive.
+    KeepAlive = 0x0c,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+/// PDU error.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PduError {
-    ByteConversion(ByteConversionError),
-    /// Found version ID invalid, not equal to [CFDP_VERSION_2].
+    /// Byte conversion error.
+    #[error("byte conversion error: {0}")]
+    ByteConversion(#[from] ByteConversionError),
+    /// Found version ID invalid, not equal to [super::CFDP_VERSION_2].
+    #[error("CFDP version missmatch, found {0}, expected {ver}", ver = super::CFDP_VERSION_2)]
     CfdpVersionMissmatch(u8),
     /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    #[error("invalid PDU entity ID length {0}, only [1, 2, 4, 8] are allowed")]
     InvalidEntityLen(u8),
     /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    #[error("invalid transaction ID length {0}")]
     InvalidTransactionSeqNumLen(u8),
+    /// Source and destination entity ID lengths do not match.
+    #[error(
+        "missmatch of PDU source ID length {src_id_len} and destination ID length {dest_id_len}"
+    )]
     SourceDestIdLenMissmatch {
+        /// Source ID length.
         src_id_len: usize,
+        /// Destination ID length.
         dest_id_len: usize,
     },
     /// Wrong directive type, for example when parsing the directive field for a file directive
     /// PDU.
+    #[error("wrong directive type, found {found:?}, expected {expected:?}")]
     WrongDirectiveType {
+        /// Found directive type.
         found: FileDirectiveType,
+        /// Expected directive type.
         expected: FileDirectiveType,
     },
     /// The directive type field contained a value not in the range of permitted values. This can
-    /// also happen if an invalid value is passed to the ACK PDU constructor.
+    /// also happen if an invalid value is passed to the ACK PDU reader.
+    #[error("invalid directive type, found {found:?}, expected {expected:?}")]
     InvalidDirectiveType {
+        /// Found raw directive type.
         found: u8,
+        /// Expected raw directive type if applicable.
         expected: Option<FileDirectiveType>,
     },
-    InvalidStartOrEndOfScopeValue,
+    /// Invalid start or end of scope for a NAK PDU.
+    #[error("nak pdu: {0}")]
+    InvalidStartOrEndOfScope(#[from] InvalidStartOrEndOfScopeError),
     /// Invalid condition code. Contains the raw detected value.
+    #[error("invalid condition code {0}")]
     InvalidConditionCode(u8),
     /// Invalid checksum type which is not part of the checksums listed in the
     /// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/).
+    #[error("invalid checksum type {0}")]
     InvalidChecksumType(u8),
+    /// File size is too large.
+    #[error("file size {0} too large")]
     FileSizeTooLarge(u64),
     /// If the CRC flag for a PDU is enabled and the checksum check fails. Contains raw 16-bit CRC.
-    ChecksumError(u16),
+    #[error("checksum error for checksum {0}")]
+    Checksum(u16),
     /// Generic error for invalid PDU formats.
-    FormatError,
+    #[error("generic PDU format error")]
+    Format,
     /// Error handling a TLV field.
-    TlvLvError(TlvLvError),
+    #[error("PDU error: {0}")]
+    TlvLv(#[from] TlvLvError),
 }
 
-impl Display for PduError {
-    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::InvalidStartOrEndOfScopeValue => {
-                write!(f, "invalid start or end of scope for NAK PDU")
-            }
-            PduError::InvalidTransactionSeqNumLen(raw_id) => {
-                write!(
-                    f,
-                    "invalid PDUtransaction seq num length {raw_id}, only [1, 2, 4, 8] are allowed"
-                )
-            }
-            PduError::CfdpVersionMissmatch(raw) => {
-                write!(
-                    f,
-                    "cfdp version missmatch, found {raw}, expected {CFDP_VERSION_2}"
-                )
-            }
-            PduError::SourceDestIdLenMissmatch {
-                src_id_len,
-                dest_id_len,
-            } => {
-                write!(
-                    f,
-                    "missmatch of PDU source length {src_id_len} and destination length {dest_id_len}"
-                )
-            }
-            PduError::ByteConversion(e) => {
-                write!(f, "{}", e)
-            }
-            PduError::FileSizeTooLarge(value) => {
-                write!(f, "file size value {value} exceeds allowed 32 bit width")
-            }
-            PduError::WrongDirectiveType { found, expected } => {
-                write!(f, "found directive type {found:?}, expected {expected:?}")
-            }
-            PduError::InvalidConditionCode(raw_code) => {
-                write!(f, "found invalid condition code with raw value {raw_code}")
-            }
-            PduError::InvalidDirectiveType { found, expected } => {
-                write!(
-                    f,
-                    "invalid directive type value {found}, expected {expected:?}"
-                )
-            }
-            PduError::InvalidChecksumType(checksum_type) => {
-                write!(f, "invalid checksum type {checksum_type}")
-            }
-            PduError::ChecksumError(checksum) => {
-                write!(f, "checksum error for CRC {checksum:#04x}")
-            }
-            PduError::TlvLvError(error) => {
-                write!(f, "pdu tlv error: {error}")
-            }
-            PduError::FormatError => {
-                write!(f, "generic PDU format error")
-            }
+impl From<InvalidAckedDirectiveCodeError> for PduError {
+    fn from(value: InvalidAckedDirectiveCodeError) -> Self {
+        Self::InvalidDirectiveType {
+            found: value.0 as u8,
+            expected: None,
         }
     }
 }
 
-#[cfg(feature = "std")]
-impl Error for PduError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        match self {
-            PduError::ByteConversion(e) => Some(e),
-            PduError::TlvLvError(e) => Some(e),
-            _ => None,
-        }
-    }
-}
-
-impl From<ByteConversionError> for PduError {
-    #[inline]
-    fn from(value: ByteConversionError) -> Self {
-        Self::ByteConversion(value)
-    }
-}
-
-impl From<TlvLvError> for PduError {
-    #[inline]
-    fn from(e: TlvLvError) -> Self {
-        Self::TlvLvError(e)
-    }
-}
-
+/// Generic trait for a PDU which can be written to bytes.
 pub trait WritablePduPacket {
+    /// Length when written to bytes.
     fn len_written(&self) -> usize;
+
+    /// Write the PDU to a raw buffer, returning the written length.
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError>;
+
+    /// Convert the PDU to an owned vector of bytes.
     #[cfg(feature = "alloc")]
     fn to_vec(&self) -> Result<Vec<u8>, PduError> {
         // This is the correct way to do this. See
@@ -179,48 +137,58 @@ pub trait WritablePduPacket {
 
 /// Abstraction trait for fields and properties common for all PDUs.
 pub trait CfdpPdu {
+    /// PDU header.
     fn pdu_header(&self) -> &PduHeader;
 
+    /// Source ID (file sender).
     #[inline]
     fn source_id(&self) -> UnsignedByteField {
         self.pdu_header().common_pdu_conf().source_entity_id
     }
 
+    /// Destination ID (file sender).
     #[inline]
     fn dest_id(&self) -> UnsignedByteField {
         self.pdu_header().common_pdu_conf().dest_entity_id
     }
 
+    /// Transaction sequence number.
     #[inline]
     fn transaction_seq_num(&self) -> UnsignedByteField {
         self.pdu_header().common_pdu_conf().transaction_seq_num
     }
 
+    /// Transmission mode.
     #[inline]
     fn transmission_mode(&self) -> TransmissionMode {
         self.pdu_header().common_pdu_conf().trans_mode
     }
 
+    /// Direction.
     #[inline]
     fn direction(&self) -> Direction {
         self.pdu_header().common_pdu_conf().direction
     }
 
+    /// CRC flag.
     #[inline]
     fn crc_flag(&self) -> CrcFlag {
         self.pdu_header().common_pdu_conf().crc_flag
     }
 
+    /// File flag.
     #[inline]
     fn file_flag(&self) -> LargeFileFlag {
         self.pdu_header().common_pdu_conf().file_flag
     }
 
+    /// PDU type.
     #[inline]
     fn pdu_type(&self) -> PduType {
         self.pdu_header().pdu_type()
     }
 
+    /// File directive type when applicable.
     fn file_directive_type(&self) -> Option<FileDirectiveType>;
 }
 
@@ -236,15 +204,21 @@ pub trait CfdpPdu {
 pub struct CommonPduConfig {
     source_entity_id: UnsignedByteField,
     dest_entity_id: UnsignedByteField,
+    /// Transaction sequence number.
     pub transaction_seq_num: UnsignedByteField,
+    /// Transmission mode.
     pub trans_mode: TransmissionMode,
+    /// File flag.
     pub file_flag: LargeFileFlag,
+    /// CRC flag.
     pub crc_flag: CrcFlag,
+    /// Direction.
     pub direction: Direction,
 }
 
 // TODO: Builder pattern might be applicable here..
 impl CommonPduConfig {
+    /// Generic constructor.
     #[inline]
     pub fn new(
         source_id: impl Into<UnsignedByteField>,
@@ -277,6 +251,7 @@ impl CommonPduConfig {
         })
     }
 
+    /// Constructor for custom byte field with default field values for the other fields.
     #[inline]
     pub fn new_with_byte_fields(
         source_id: impl Into<UnsignedByteField>,
@@ -294,6 +269,7 @@ impl CommonPduConfig {
         )
     }
 
+    /// Source ID (file sender).
     #[inline]
     pub fn source_id(&self) -> UnsignedByteField {
         self.source_entity_id
@@ -322,6 +298,7 @@ impl CommonPduConfig {
         Ok((source_id, dest_id))
     }
 
+    /// Set the source and destination ID field.
     #[inline]
     pub fn set_source_and_dest_id(
         &mut self,
@@ -334,6 +311,7 @@ impl CommonPduConfig {
         Ok(())
     }
 
+    /// Destination ID (file receiver).
     #[inline]
     pub fn dest_id(&self) -> UnsignedByteField {
         self.dest_entity_id
@@ -372,6 +350,7 @@ impl PartialEq for CommonPduConfig {
     }
 }
 
+/// Fixed header length of the PDU header.
 pub const FIXED_HEADER_LEN: usize = 4;
 
 /// Abstraction for the PDU header common to all CFDP PDUs.
@@ -389,6 +368,10 @@ pub struct PduHeader {
 }
 
 impl PduHeader {
+    /// Fixed length of the PDU header when written to a raw buffer.
+    pub const FIXED_LEN: usize = FIXED_HEADER_LEN;
+
+    /// Constructor for a File Data PDU header.
     #[inline]
     pub fn new_for_file_data(
         pdu_conf: CommonPduConfig,
@@ -405,6 +388,7 @@ impl PduHeader {
         )
     }
 
+    /// Constructor for a file data PDU.
     #[inline]
     pub fn new_for_file_data_default(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
         Self::new_generic(
@@ -415,8 +399,10 @@ impl PduHeader {
             SegmentationControl::NoRecordBoundaryPreservation,
         )
     }
+
+    /// Constructor for a file directive PDU.
     #[inline]
-    pub fn new_no_file_data(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
+    pub fn new_for_file_directive(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
         Self::new_generic(
             PduType::FileDirective,
             pdu_conf,
@@ -426,6 +412,19 @@ impl PduHeader {
         )
     }
 
+    /// Constructor from a given [CommonPduConfig] and for a file directive PDU.
+    #[inline]
+    pub fn from_pdu_conf_for_file_directive(pdu_conf: CommonPduConfig) -> Self {
+        Self::new_generic(
+            PduType::FileDirective,
+            pdu_conf,
+            0,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        )
+    }
+
+    /// Generic constructor.
     #[inline]
     pub fn new_generic(
         pdu_type: PduType,
@@ -452,6 +451,7 @@ impl PduHeader {
             + self.pdu_conf.dest_entity_id.size()
     }
 
+    /// PDU data field length.
     #[inline]
     pub fn pdu_datafield_len(&self) -> usize {
         self.pdu_datafield_len.into()
@@ -464,15 +464,15 @@ impl PduHeader {
         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(),
-            });
-        }
+    /// Write the header to a raw buffer, returning the written length on success.
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        // The API does not allow passing entity IDs with different sizes, so this should
+        // never happen.
+        assert_eq!(
+            self.pdu_conf.source_entity_id.size(),
+            self.pdu_conf.dest_entity_id.size(),
+            "unexpected missmatch of source and destination entity ID length"
+        );
         if buf.len()
             < FIXED_HEADER_LEN
                 + self.pdu_conf.source_entity_id.size()
@@ -481,8 +481,7 @@ impl PduHeader {
             return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: FIXED_HEADER_LEN,
-            }
-            .into());
+            });
         }
         let mut current_idx = 0;
         buf[current_idx] = (CFDP_VERSION_2 << 5)
@@ -532,7 +531,7 @@ impl PduHeader {
             let mut digest = CRC_CCITT_FALSE.digest();
             digest.update(&buf[..self.pdu_len()]);
             if digest.finalize() != 0 {
-                return Err(PduError::ChecksumError(u16::from_be_bytes(
+                return Err(PduError::Checksum(u16::from_be_bytes(
                     buf[self.pdu_len() - 2..self.pdu_len()].try_into().unwrap(),
                 )));
             }
@@ -633,20 +632,25 @@ impl PduHeader {
         ))
     }
 
+    /// PDU type.
     #[inline]
     pub fn pdu_type(&self) -> PduType {
         self.pdu_type
     }
 
+    /// Common PDU configuration fields.
     #[inline]
     pub fn common_pdu_conf(&self) -> &CommonPduConfig {
         &self.pdu_conf
     }
 
+    /// Segment metadata flag.
+    #[inline]
     pub fn seg_metadata_flag(&self) -> SegmentMetadataFlag {
         self.seg_metadata_flag
     }
 
+    /// Segmentation Control.
     #[inline]
     pub fn seg_ctrl(&self) -> SegmentationControl {
         self.seg_ctrl
@@ -812,7 +816,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         assert_eq!(pdu_header.pdu_type(), PduType::FileDirective);
         let common_conf_ref = pdu_header.common_pdu_conf();
         assert_eq!(*common_conf_ref, common_pdu_cfg);
@@ -878,7 +882,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -895,7 +899,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -968,7 +972,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -981,7 +985,7 @@ mod tests {
             assert_eq!(raw_version, CFDP_VERSION_2 + 1);
             assert_eq!(
                 error.to_string(),
-                "cfdp version missmatch, found 2, expected 1"
+                "CFDP version missmatch, found 2, expected 1"
             );
         } else {
             panic!("invalid exception: {}", error);
@@ -1013,7 +1017,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -1029,7 +1033,7 @@ mod tests {
             assert_eq!(expected, 7);
             assert_eq!(
                 error.to_string(),
-                "source slice with size 6 too small, expected at least 7 bytes"
+                "byte conversion error: source slice with size 6 too small, expected at least 7 bytes"
             );
         }
     }
@@ -1084,7 +1088,7 @@ mod tests {
             assert_eq!(dest_id_len, 2);
             assert_eq!(
                 error.to_string(),
-                "missmatch of PDU source length 1 and destination length 2"
+                "missmatch of PDU source ID length 1 and destination ID length 2"
             );
         }
     }
@@ -1096,7 +1100,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -1120,7 +1124,7 @@ mod tests {
         let transaction_id = UnsignedByteFieldU8::new(3);
         let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
-        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let pdu_header = PduHeader::new_for_file_directive(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
         let res = pdu_header.write_to_bytes(&mut buf);
         assert!(res.is_ok());
@@ -1152,4 +1156,12 @@ mod tests {
         let common_pdu_cfg_1 = common_pdu_cfg_0;
         assert_eq!(common_pdu_cfg_0, common_pdu_cfg_1);
     }
+
+    #[test]
+    fn test_ctor_from_pdu_conf() {
+        assert_eq!(
+            PduHeader::from_pdu_conf_for_file_directive(CommonPduConfig::default()),
+            PduHeader::new_for_file_directive(CommonPduConfig::default(), 0)
+        );
+    }
 }

src/cfdp/tlv/mod.rs

@@ -9,19 +9,27 @@ use crate::ByteConversionError;
 use alloc::vec;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
+#[cfg(feature = "alloc")]
+pub use alloc_mod::*;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+use super::{InvalidTlvTypeFieldError, TlvLvDataTooLargeError};
+
 pub mod msg_to_user;
 
+/// Minimum length of a type-length-value structure, including type and length fields.
 pub const MIN_TLV_LEN: usize = 2;
 
+/// Trait for generic TLV structures.
 pub trait GenericTlv {
+    /// TLV type field.
     fn tlv_type_field(&self) -> TlvTypeField;
 
     /// Checks whether the type field contains one of the standard types specified in the CFDP
     /// standard and is part of the [TlvType] enum.
+    #[inline]
     fn is_standard_tlv(&self) -> bool {
         if let TlvTypeField::Standard(_) = self.tlv_type_field() {
             return true;
@@ -30,6 +38,7 @@ pub trait GenericTlv {
     }
 
     /// Returns the standard TLV type if the TLV field is not a custom field
+    #[inline]
     fn tlv_type(&self) -> Option<TlvType> {
         if let TlvTypeField::Standard(tlv_type) = self.tlv_type_field() {
             Some(tlv_type)
@@ -39,9 +48,40 @@ pub trait GenericTlv {
     }
 }
 
+/// Readable TLV structure trait.
+pub trait ReadableTlv {
+    /// Value field of the TLV.
+    fn value(&self) -> &[u8];
+
+    /// Checks whether the value field is empty.
+    #[inline]
+    fn is_empty(&self) -> bool {
+        self.value().is_empty()
+    }
+
+    /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
+    /// [Self::value]
+    #[inline]
+    fn len_value(&self) -> usize {
+        self.value().len()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    #[inline]
+    fn len_full(&self) -> usize {
+        self.len_value() + 2
+    }
+}
+
+/// Writable TLV structure trait.
 pub trait WritableTlv {
+    /// Write the TLV to bytes.
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+
+    /// Length of the written TLV.
     fn len_written(&self) -> usize;
+
+    /// Convenience method to write the TLV to an owned [alloc::vec::Vec].
     #[cfg(feature = "alloc")]
     fn to_vec(&self) -> Vec<u8> {
         let mut buf = vec![0; self.len_written()];
@@ -50,34 +90,50 @@ pub trait WritableTlv {
     }
 }
 
+/// TLV type.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum TlvType {
+    /// Filestore request.
     FilestoreRequest = 0x00,
+    /// Filestore response.
     FilestoreResponse = 0x01,
+    /// Message to user.
     MsgToUser = 0x02,
+    /// Fault handler.
     FaultHandler = 0x04,
+    /// Flow label.
     FlowLabel = 0x05,
+    /// Entity ID.
     EntityId = 0x06,
 }
 
+/// TLV type field variants.
+///
+/// This allows specifying custom variants as well.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum TlvTypeField {
+    /// Standard TLV types.
     Standard(TlvType),
+    /// Custom TLV type.
     Custom(u8),
 }
 
+/// Filestore action codes as specified in the standard.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum FilestoreActionCode {
+    /// Create file.
     CreateFile = 0b0000,
+    /// Delete file.
     DeleteFile = 0b0001,
+    /// Rename file.
     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
@@ -86,9 +142,13 @@ pub enum FilestoreActionCode {
     /// This operation replaces the content of the first specified file with the content of
     /// the secondly specified file.
     ReplaceFile = 0b0100,
+    /// Create directory.
     CreateDirectory = 0b0101,
+    /// Remove directory.
     RemoveDirectory = 0b0110,
+    /// Deny file.
     DenyFile = 0b0111,
+    /// Deny directory.
     DenyDirectory = 0b1000,
 }
 
@@ -129,14 +189,22 @@ pub struct Tlv<'data> {
 }
 
 impl<'data> Tlv<'data> {
-    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvError> {
+    /// Minimum length of a TLV structure, including type and length fields.
+    pub const MIN_LEN: usize = MIN_TLV_LEN;
+
+    /// Generic constructor for a TLV structure.
+    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv<'_>, TlvLvDataTooLargeError> {
         Ok(Tlv {
             tlv_type_field: TlvTypeField::Standard(tlv_type),
             lv: Lv::new(data)?,
         })
     }
 
-    pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Result<Tlv, TlvLvError> {
+    /// Constructor for a TLV with a custom type field.
+    pub fn new_with_custom_type(
+        tlv_type: u8,
+        data: &[u8],
+    ) -> Result<Tlv<'_>, TlvLvDataTooLargeError> {
         Ok(Tlv {
             tlv_type_field: TlvTypeField::Custom(tlv_type),
             lv: Lv::new(data)?,
@@ -151,31 +219,11 @@ impl<'data> Tlv<'data> {
         }
     }
 
-    pub fn value(&self) -> &[u8] {
-        self.lv.value()
-    }
-
-    /// Checks whether the value field is empty.
-    pub fn is_empty(&self) -> bool {
-        self.value().is_empty()
-    }
-
-    /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
-    /// [Self::value]
-    pub fn len_value(&self) -> usize {
-        self.value().len()
-    }
-
-    /// Returns the full raw length, including the length byte.
-    pub fn len_full(&self) -> usize {
-        self.len_value() + 2
-    }
-
     /// Creates a TLV give a raw bytestream. Please note that is is not necessary to pass the
     /// bytestream with the exact size of the expected TLV. This function will take care
     /// of parsing the length byte, and the length of the parsed TLV can be retrieved using
     /// [Self::len_full].
-    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, ByteConversionError> {
         generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
         let mut tlv = Self {
             tlv_type_field: TlvTypeField::from(buf[0]),
@@ -189,9 +237,32 @@ impl<'data> Tlv<'data> {
 
     /// If the TLV was generated from a raw bytestream using [Self::from_bytes], the raw start
     /// of the TLV can be retrieved with this method.
+    #[inline]
     pub fn raw_data(&self) -> Option<&[u8]> {
         self.lv.raw_data()
     }
+
+    /// Converts to an owned TLV variant, allocating memory for the value field.
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        TlvOwned {
+            tlv_type_field: self.tlv_type_field,
+            data: self.value().to_vec(),
+        }
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl PartialEq<TlvOwned> for Tlv<'_> {
+    fn eq(&self, other: &TlvOwned) -> bool {
+        self.tlv_type_field == other.tlv_type_field && self.value() == other.value()
+    }
+}
+
+impl ReadableTlv for Tlv<'_> {
+    fn value(&self) -> &[u8] {
+        self.lv.value()
+    }
 }
 
 impl WritableTlv for Tlv<'_> {
@@ -201,31 +272,124 @@ impl WritableTlv for Tlv<'_> {
         self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
         Ok(self.len_full())
     }
+
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 }
 
 impl GenericTlv for Tlv<'_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         self.tlv_type_field
     }
 }
 
-pub(crate) fn verify_tlv_type(raw_type: u8, expected_tlv_type: TlvType) -> Result<(), TlvLvError> {
-    let tlv_type = TlvType::try_from(raw_type).map_err(|_| TlvLvError::InvalidTlvTypeField {
-        found: raw_type,
-        expected: Some(expected_tlv_type.into()),
-    })?;
-    if tlv_type != expected_tlv_type {
-        return Err(TlvLvError::InvalidTlvTypeField {
-            found: tlv_type as u8,
-            expected: Some(expected_tlv_type as u8),
-        });
+/// Component of the TLV module which require [alloc] support.
+#[cfg(feature = "alloc")]
+pub mod alloc_mod {
+    use super::*;
+
+    /// Owned variant of [Tlv] which is consequently [Clone]able and does not have a lifetime
+    /// associated to a data slice.
+    #[derive(Debug, Clone, PartialEq, Eq)]
+    #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+    #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+    pub struct TlvOwned {
+        pub(crate) tlv_type_field: TlvTypeField,
+        pub(crate) data: Vec<u8>,
+    }
+
+    impl TlvOwned {
+        /// Generic constructor.
+        pub fn new(tlv_type: TlvType, data: &[u8]) -> Self {
+            Self {
+                tlv_type_field: TlvTypeField::Standard(tlv_type),
+                data: data.to_vec(),
+            }
+        }
+
+        /// Generic constructor with a custom TLV type.
+        pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Self {
+            Self {
+                tlv_type_field: TlvTypeField::Custom(tlv_type),
+                data: data.to_vec(),
+            }
+        }
+
+        /// Creates a TLV with an empty value field.
+        pub fn new_empty(tlv_type: TlvType) -> Self {
+            Self {
+                tlv_type_field: TlvTypeField::Standard(tlv_type),
+                data: Vec::new(),
+            }
+        }
+
+        /// Write to a byte slice.
+        pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+            generic_len_check_data_serialization(buf, self.data.len(), MIN_TLV_LEN)?;
+            buf[0] = self.tlv_type_field.into();
+            buf[1] = self.data.len() as u8;
+            buf[2..2 + self.data.len()].copy_from_slice(&self.data);
+            Ok(self.len_written())
+        }
+
+        #[inline]
+        fn len_written(&self) -> usize {
+            self.data.len() + 2
+        }
+
+        /// Convert to [Tlv]
+        pub fn as_tlv(&self) -> Tlv<'_> {
+            Tlv {
+                tlv_type_field: self.tlv_type_field,
+                // The API should ensure that the data length is never to large, so the unwrap for the
+                // LV creation should never be an issue.
+                lv: Lv::new(&self.data).expect("lv creation failed unexpectedly"),
+            }
+        }
+    }
+
+    impl ReadableTlv for TlvOwned {
+        #[inline]
+        fn value(&self) -> &[u8] {
+            &self.data
+        }
+    }
+
+    impl WritableTlv for TlvOwned {
+        fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+            self.write_to_bytes(buf)
+        }
+
+        #[inline]
+        fn len_written(&self) -> usize {
+            self.len_written()
+        }
+    }
+
+    impl GenericTlv for TlvOwned {
+        #[inline]
+        fn tlv_type_field(&self) -> TlvTypeField {
+            self.tlv_type_field
+        }
+    }
+
+    impl From<Tlv<'_>> for TlvOwned {
+        fn from(value: Tlv<'_>) -> Self {
+            value.to_owned()
+        }
+    }
+
+    impl PartialEq<Tlv<'_>> for TlvOwned {
+        fn eq(&self, other: &Tlv) -> bool {
+            self.tlv_type_field == other.tlv_type_field && self.data == other.value()
+        }
     }
-    Ok(())
 }
 
+/// Entity ID TLV.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -234,6 +398,8 @@ pub struct EntityIdTlv {
 }
 
 impl EntityIdTlv {
+    /// Constructor.
+    #[inline]
     pub fn new(entity_id: UnsignedByteField) -> Self {
         Self { entity_id }
     }
@@ -248,18 +414,25 @@ impl EntityIdTlv {
         Ok(())
     }
 
+    /// Entity ID.
+    #[inline]
     pub fn entity_id(&self) -> &UnsignedByteField {
         &self.entity_id
     }
 
+    /// Length of the value field.
+    #[inline]
     pub fn len_value(&self) -> usize {
         self.entity_id.size()
     }
 
+    /// Full length of the TLV, including type and length fields.
+    #[inline]
     pub fn len_full(&self) -> usize {
         2 + self.entity_id.size()
     }
 
+    /// Create from a raw bytestream.
     pub fn from_bytes(buf: &[u8]) -> Result<Self, TlvLvError> {
         Self::len_check(buf)?;
         verify_tlv_type(buf[0], TlvType::EntityId)?;
@@ -273,19 +446,14 @@ impl EntityIdTlv {
     }
 
     /// Convert to a generic [Tlv], which also erases the programmatic type information.
-    pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv, ByteConversionError> {
+    pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv<'_>, ByteConversionError> {
         Self::len_check(buf)?;
         self.entity_id
             .write_to_be_bytes(&mut buf[2..2 + self.entity_id.size()])?;
-        Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.size()]).map_err(|e| match e {
-            TlvLvError::ByteConversion(e) => e,
-            // All other errors are impossible.
-            _ => panic!("unexpected TLV error"),
-        })
+        // Can't fail.
+        Ok(Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.size()]).unwrap())
     }
-}
 
-impl WritableTlv for EntityIdTlv {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         Self::len_check(buf)?;
         buf[0] = TlvType::EntityId as u8;
@@ -293,35 +461,50 @@ impl WritableTlv for EntityIdTlv {
         Ok(2 + self.entity_id.write_to_be_bytes(&mut buf[2..])?)
     }
 
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 }
 
+impl WritableTlv for EntityIdTlv {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.write_to_bytes(buf)
+    }
+
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 impl GenericTlv for EntityIdTlv {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         TlvTypeField::Standard(TlvType::EntityId)
     }
 }
 
-impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
+impl TryFrom<Tlv<'_>> for EntityIdTlv {
     type Error = TlvLvError;
 
-    fn try_from(value: Tlv) -> Result<Self, Self::Error> {
+    fn try_from(value: Tlv) -> Result<Self, TlvLvError> {
         match value.tlv_type_field {
             TlvTypeField::Standard(tlv_type) => {
                 if tlv_type != TlvType::EntityId {
-                    return Err(TlvLvError::InvalidTlvTypeField {
+                    return Err(InvalidTlvTypeFieldError {
                         found: tlv_type as u8,
                         expected: Some(TlvType::EntityId as u8),
-                    });
+                    }
+                    .into());
                 }
             }
             TlvTypeField::Custom(val) => {
-                return Err(TlvLvError::InvalidTlvTypeField {
+                return Err(InvalidTlvTypeFieldError {
                     found: val,
                     expected: Some(TlvType::EntityId as u8),
-                });
+                }
+                .into());
             }
         }
         let len_value = value.value().len();
@@ -341,6 +524,8 @@ impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
     }
 }
 
+/// Does the [FilestoreActionCode] have a second filename?
+#[inline]
 pub fn fs_request_has_second_filename(action_code: FilestoreActionCode) -> bool {
     if action_code == FilestoreActionCode::RenameFile
         || action_code == FilestoreActionCode::AppendFile
@@ -363,6 +548,7 @@ struct FilestoreTlvBase<'first_name, 'second_name> {
 }
 
 impl FilestoreTlvBase<'_, '_> {
+    #[inline]
     fn base_len_value(&self) -> usize {
         let mut len = 1 + self.first_name.len_full();
         if let Some(second_name) = self.second_name {
@@ -372,6 +558,7 @@ impl FilestoreTlvBase<'_, '_> {
     }
 }
 
+/// Filestore request TLV.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct FilestoreRequestTlv<'first_name, 'second_name> {
@@ -380,14 +567,17 @@ pub struct FilestoreRequestTlv<'first_name, 'second_name> {
 }
 
 impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
+    /// Constructor for file creation.
     pub fn new_create_file(file_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
         Self::new(FilestoreActionCode::CreateFile, file_name, None)
     }
 
+    /// Constructor for file deletion.
     pub fn new_delete_file(file_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
         Self::new(FilestoreActionCode::DeleteFile, file_name, None)
     }
 
+    /// Constructor for file renaming.
     pub fn new_rename_file(
         source_name: Lv<'first_name>,
         target_name: Lv<'second_name>,
@@ -427,18 +617,22 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
         )
     }
 
+    /// Constructor for directory creation.
     pub fn new_create_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
         Self::new(FilestoreActionCode::CreateDirectory, dir_name, None)
     }
 
+    /// Constructor for directory removal.
     pub fn new_remove_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
         Self::new(FilestoreActionCode::RemoveDirectory, dir_name, None)
     }
 
+    /// Constructor for file denial.
     pub fn new_deny_file(file_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
         Self::new(FilestoreActionCode::DenyFile, file_name, None)
     }
 
+    /// Constructor for directory denial.
     pub fn new_deny_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
         Self::new(FilestoreActionCode::DenyDirectory, dir_name, None)
     }
@@ -472,26 +666,37 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
         })
     }
 
+    /// Action code.
+    #[inline]
     pub fn action_code(&self) -> FilestoreActionCode {
         self.base.action_code
     }
 
+    /// First name as [Lv].
+    #[inline]
     pub fn first_name(&self) -> Lv<'first_name> {
         self.base.first_name
     }
 
+    /// First name as optional [Lv].
+    #[inline]
     pub fn second_name(&self) -> Option<Lv<'second_name>> {
         self.base.second_name
     }
 
+    /// Length of the value field.
+    #[inline]
     pub fn len_value(&self) -> usize {
         self.base.base_len_value()
     }
 
+    /// Full TLV length.
+    #[inline]
     pub fn len_full(&self) -> usize {
         2 + self.len_value()
     }
 
+    /// Construct from a raw bytestream.
     pub fn from_bytes<'longest: 'first_name + 'second_name>(
         buf: &'longest [u8],
     ) -> Result<Self, TlvLvError> {
@@ -526,9 +731,7 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
             },
         })
     }
-}
 
-impl WritableTlv for FilestoreRequestTlv<'_, '_> {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.len_full() {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -554,17 +757,31 @@ impl WritableTlv for FilestoreRequestTlv<'_, '_> {
         Ok(current_idx)
     }
 
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 }
 
+impl WritableTlv for FilestoreRequestTlv<'_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.write_to_bytes(buf)
+    }
+
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 impl GenericTlv for FilestoreRequestTlv<'_, '_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         TlvTypeField::Standard(TlvType::FilestoreRequest)
     }
 }
 
+/// Filestore response TLV.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -596,6 +813,8 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
             Lv::new_empty(),
         )
     }
+
+    /// Generic constructor.
     pub fn new(
         action_code: FilestoreActionCode,
         status_code: u8,
@@ -624,6 +843,7 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
         })
     }
 
+    /// Check whether this response has a second filename.
     pub fn has_second_filename(action_code: FilestoreActionCode) -> bool {
         if action_code == FilestoreActionCode::RenameFile
             || action_code == FilestoreActionCode::AppendFile
@@ -634,30 +854,43 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
         false
     }
 
+    /// Action code.
+    #[inline]
     pub fn action_code(&self) -> FilestoreActionCode {
         self.base.action_code
     }
 
+    /// Status code.
+    #[inline]
     pub fn status_code(&self) -> u8 {
         self.status_code
     }
 
+    /// First name as [Lv].
+    #[inline]
     pub fn first_name(&self) -> Lv<'first_name> {
         self.base.first_name
     }
 
+    /// Optional second name as [Lv].
+    #[inline]
     pub fn second_name(&self) -> Option<Lv<'second_name>> {
         self.base.second_name
     }
 
+    /// Length of the value field.
+    #[inline]
     pub fn len_value(&self) -> usize {
         self.base.base_len_value() + self.filestore_message.len_full()
     }
 
+    /// Full length of the TLV.
+    #[inline]
     pub fn len_full(&self) -> usize {
         2 + self.len_value()
     }
 
+    /// Construct from a raw bytestream.
     pub fn from_bytes<'buf: 'first_name + 'second_name + 'fs_msg>(
         buf: &'buf [u8],
     ) -> Result<Self, TlvLvError> {
@@ -711,9 +944,7 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
             filestore_message,
         })
     }
-}
 
-impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
     fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.len_full() {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -746,12 +977,41 @@ impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
     }
 }
 
+impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.write_to_bytes(buf)
+    }
+
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+}
+
 impl GenericTlv for FilestoreResponseTlv<'_, '_, '_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         TlvTypeField::Standard(TlvType::FilestoreResponse)
     }
 }
 
+pub(crate) fn verify_tlv_type(
+    raw_type: u8,
+    expected_tlv_type: TlvType,
+) -> Result<(), InvalidTlvTypeFieldError> {
+    let tlv_type = TlvType::try_from(raw_type).map_err(|_| InvalidTlvTypeFieldError {
+        found: raw_type,
+        expected: Some(expected_tlv_type.into()),
+    })?;
+    if tlv_type != expected_tlv_type {
+        return Err(InvalidTlvTypeFieldError {
+            found: tlv_type as u8,
+            expected: Some(expected_tlv_type as u8),
+        });
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -939,14 +1199,14 @@ mod tests {
         let tlv_res = Tlv::new(TlvType::MsgToUser, &buf_too_large);
         assert!(tlv_res.is_err());
         let error = tlv_res.unwrap_err();
-        if let TlvLvError::DataTooLarge(size) = error {
-            assert_eq!(size, u8::MAX as usize + 1);
-            assert_eq!(
-                error.to_string(),
-                "data with size 256 larger than allowed 255 bytes"
-            );
-        } else {
-            panic!("unexpected error {:?}", error);
+        match error {
+            TlvLvDataTooLargeError(size) => {
+                assert_eq!(size, u8::MAX as usize + 1);
+                assert_eq!(
+                    error.to_string(),
+                    "data with size 256 larger than allowed 255 bytes"
+                );
+            }
         }
     }
 
@@ -1256,7 +1516,8 @@ mod tests {
         let error = EntityIdTlv::try_from(msg_to_user_tlv);
         assert!(error.is_err());
         let error = error.unwrap_err();
-        if let TlvLvError::InvalidTlvTypeField { found, expected } = error {
+        if let TlvLvError::InvalidTlvTypeField(InvalidTlvTypeFieldError { found, expected }) = error
+        {
             assert_eq!(found, TlvType::MsgToUser as u8);
             assert_eq!(expected, Some(TlvType::EntityId as u8));
             assert_eq!(
@@ -1300,4 +1561,71 @@ mod tests {
         assert_eq!(tlv_as_vec[0], 20);
         assert_eq!(tlv_as_vec[1], 0);
     }
+
+    #[test]
+    fn test_tlv_to_owned() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
+        assert!(tlv_res.is_ok());
+        let tlv_res = tlv_res.unwrap();
+        let tlv_owned = tlv_res.to_owned();
+        assert_eq!(tlv_res, tlv_owned);
+        let tlv_owned_from_conversion: TlvOwned = tlv_res.into();
+        assert_eq!(tlv_owned_from_conversion, tlv_owned);
+        assert_eq!(tlv_owned_from_conversion, tlv_res);
+    }
+
+    #[test]
+    fn test_owned_tlv() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = TlvOwned::new(TlvType::EntityId, &buf[0..1]);
+        assert_eq!(
+            tlv_res.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::EntityId)
+        );
+        assert_eq!(tlv_res.len_full(), 3);
+        assert_eq!(tlv_res.value().len(), 1);
+        assert_eq!(tlv_res.len_value(), 1);
+        assert!(!tlv_res.is_empty());
+        assert_eq!(tlv_res.value()[0], 5);
+    }
+
+    #[test]
+    fn test_owned_tlv_empty() {
+        let tlv_res = TlvOwned::new_empty(TlvType::FlowLabel);
+        assert_eq!(
+            tlv_res.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::FlowLabel)
+        );
+        assert_eq!(tlv_res.len_full(), 2);
+        assert_eq!(tlv_res.value().len(), 0);
+        assert_eq!(tlv_res.len_value(), 0);
+        assert!(tlv_res.is_empty());
+    }
+
+    #[test]
+    fn test_owned_tlv_custom_type() {
+        let tlv_res = TlvOwned::new_with_custom_type(32, &[]);
+        assert_eq!(tlv_res.tlv_type_field(), TlvTypeField::Custom(32));
+        assert_eq!(tlv_res.len_full(), 2);
+        assert_eq!(tlv_res.value().len(), 0);
+        assert_eq!(tlv_res.len_value(), 0);
+        assert!(tlv_res.is_empty());
+    }
+
+    #[test]
+    fn test_owned_tlv_conversion_to_bytes() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
+        assert!(tlv_res.is_ok());
+        let tlv_res = tlv_res.unwrap();
+        let tlv_owned_from_conversion: TlvOwned = tlv_res.into();
+        assert_eq!(tlv_res.to_vec(), tlv_owned_from_conversion.to_vec());
+    }
 }

src/cfdp/tlv/msg_to_user.rs

@@ -1,16 +1,23 @@
 //! Abstractions for the Message to User CFDP TLV subtype.
-use super::{GenericTlv, Tlv, TlvLvError, TlvType, TlvTypeField, WritableTlv};
-use crate::ByteConversionError;
+#[cfg(feature = "alloc")]
+use super::TlvOwned;
+use super::{GenericTlv, ReadableTlv, Tlv, TlvLvError, TlvType, TlvTypeField, WritableTlv};
+use crate::{
+    cfdp::{InvalidTlvTypeFieldError, TlvLvDataTooLargeError},
+    ByteConversionError,
+};
 use delegate::delegate;
 
+/// Message To User TLV structure.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub struct MsgToUserTlv<'data> {
+    /// Wrapped generic TLV structure.
     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> {
+    pub fn new(value: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvDataTooLargeError> {
         Ok(Self {
             tlv: Tlv::new(TlvType::MsgToUser, value)?,
         })
@@ -18,7 +25,9 @@ impl<'data> MsgToUserTlv<'data> {
 
     delegate! {
         to self.tlv {
+            /// Value field of the TLV.
             pub fn value(&self) -> &[u8];
+
             /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
             /// [Self::value]
             pub fn len_value(&self) -> usize;
@@ -32,12 +41,16 @@ impl<'data> MsgToUserTlv<'data> {
         }
     }
 
+    /// Is this a standard TLV?
+    #[inline]
     pub fn is_standard_tlv(&self) -> bool {
         true
     }
 
-    pub fn tlv_type(&self) -> Option<TlvType> {
-        Some(TlvType::MsgToUser)
+    /// TLV type field.
+    #[inline]
+    pub fn tlv_type(&self) -> TlvType {
+        TlvType::MsgToUser
     }
 
     /// Check whether this message is a reserved CFDP message like a Proxy Operation Message.
@@ -60,36 +73,68 @@ impl<'data> MsgToUserTlv<'data> {
         match msg_to_user.tlv.tlv_type_field() {
             TlvTypeField::Standard(tlv_type) => {
                 if tlv_type != TlvType::MsgToUser {
-                    return Err(TlvLvError::InvalidTlvTypeField {
+                    return Err(InvalidTlvTypeFieldError {
                         found: tlv_type as u8,
                         expected: Some(TlvType::MsgToUser as u8),
-                    });
+                    }
+                    .into());
                 }
             }
             TlvTypeField::Custom(raw) => {
-                return Err(TlvLvError::InvalidTlvTypeField {
+                return Err(InvalidTlvTypeFieldError {
                     found: raw,
                     expected: Some(TlvType::MsgToUser as u8),
-                });
+                }
+                .into());
             }
         }
         Ok(msg_to_user)
     }
-}
 
-impl WritableTlv for MsgToUserTlv<'_> {
+    /// Convert to a generic [Tlv].
+    #[inline]
+    pub fn to_tlv(&self) -> Tlv<'data> {
+        self.tlv
+    }
+
+    /// Convert to an [TlvOwned].
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        self.tlv.to_owned()
+    }
+
+    #[inline]
     fn len_written(&self) -> usize {
         self.len_full()
     }
 
     delegate!(
         to self.tlv {
-            fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+            /// Write the TLV to a byte buffer.
+            pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
         }
     );
 }
 
+impl<'a> From<MsgToUserTlv<'a>> for Tlv<'a> {
+    fn from(value: MsgToUserTlv<'a>) -> Tlv<'a> {
+        value.to_tlv()
+    }
+}
+
+impl WritableTlv for MsgToUserTlv<'_> {
+    #[inline]
+    fn len_written(&self) -> usize {
+        self.len_written()
+    }
+
+    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.tlv.write_to_bytes(buf)
+    }
+}
+
 impl GenericTlv for MsgToUserTlv<'_> {
+    #[inline]
     fn tlv_type_field(&self) -> TlvTypeField {
         self.tlv.tlv_type_field()
     }
@@ -106,7 +151,7 @@ mod tests {
         assert!(msg_to_user.is_ok());
         let msg_to_user = msg_to_user.unwrap();
         assert!(msg_to_user.is_standard_tlv());
-        assert_eq!(msg_to_user.tlv_type().unwrap(), TlvType::MsgToUser);
+        assert_eq!(msg_to_user.tlv_type(), TlvType::MsgToUser);
         assert_eq!(
             msg_to_user.tlv_type_field(),
             TlvTypeField::Standard(TlvType::MsgToUser)
@@ -139,6 +184,40 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_msg_to_user_type_reduction() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let tlv = msg_to_user.to_tlv();
+        assert_eq!(
+            tlv.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+
+        assert_eq!(tlv.value(), custom_value);
+    }
+
+    #[test]
+    fn test_msg_to_user_to_tlv() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let tlv: Tlv = msg_to_user.into();
+        assert_eq!(msg_to_user.to_tlv(), tlv);
+    }
+
+    #[test]
+    fn test_msg_to_user_owner_converter() {
+        let custom_value: [u8; 4] = [1, 2, 3, 4];
+        let msg_to_user = MsgToUserTlv::new(&custom_value).unwrap();
+        let tlv = msg_to_user.to_owned();
+        assert_eq!(
+            tlv.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+
+        assert_eq!(tlv.value(), custom_value);
+    }
+
     #[test]
     fn test_reserved_msg_deserialization() {
         let custom_value: [u8; 3] = [1, 2, 3];
@@ -154,9 +233,9 @@ mod tests {
     fn test_reserved_msg_deserialization_invalid_type() {
         let trash: [u8; 5] = [TlvType::FlowLabel as u8, 3, 1, 2, 3];
         let error = MsgToUserTlv::from_bytes(&trash).unwrap_err();
-        if let TlvLvError::InvalidTlvTypeField { found, expected } = error {
-            assert_eq!(found, TlvType::FlowLabel as u8);
-            assert_eq!(expected, Some(TlvType::MsgToUser as u8));
+        if let TlvLvError::InvalidTlvTypeField(inner) = error {
+            assert_eq!(inner.found, TlvType::FlowLabel as u8);
+            assert_eq!(inner.expected, Some(TlvType::MsgToUser as u8));
         } else {
             panic!("Wrong error type returned: {:?}", error);
         }

src/crc.rs

@@ -0,0 +1,15 @@
+//! # CRC checksum support.
+//!
+//! Thin wrapper around the [crc] crate.
+
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
+/// a [crc::NoTable] as the CRC implementation.
+pub const CRC_CCITT_FALSE_NO_TABLE: crc::Crc<u16, crc::NoTable> =
+    crc::Crc::<u16, crc::NoTable>::new(&crc::CRC_16_IBM_3740);
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
+/// [crc::Table<1>] as the CRC implementation.
+pub const CRC_CCITT_FALSE: crc::Crc<u16> = crc::Crc::<u16>::new(&crc::CRC_16_IBM_3740);
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
+/// a [crc::Table<16>] large table as the CRC implementation.
+pub const CRC_CCITT_FALSE_BIG_TABLE: crc::Crc<u16, crc::Table<16>> =
+    crc::Crc::<u16, crc::Table<16>>::new(&crc::CRC_16_IBM_3740);

src/ecss/event.rs

@@ -3,17 +3,26 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// Event service subtype ID.
 #[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[repr(u8)]
-pub enum Subservice {
+pub enum MessageSubtypeId {
+    /// Telemetry - Info report.
     TmInfoReport = 1,
+    /// Telemetry - Low severity report.
     TmLowSeverityReport = 2,
+    /// Telemetry - Medium severity report.
     TmMediumSeverityReport = 3,
+    /// Telemetry - High severity report.
     TmHighSeverityReport = 4,
+    /// Telecommand - Enable event generation.
     TcEnableEventGeneration = 5,
+    /// Telecommand - Disable event generation.
     TcDisableEventGeneration = 6,
+    /// Telecommand - Report disabled list.
     TcReportDisabledList = 7,
+    /// Telemetry - Disabled events report.
     TmDisabledEventsReport = 8,
 }
 
@@ -23,19 +32,19 @@ mod tests {
 
     #[test]
     fn test_conv_into_u8() {
-        let subservice: u8 = Subservice::TmLowSeverityReport.into();
+        let subservice: u8 = MessageSubtypeId::TmLowSeverityReport.into();
         assert_eq!(subservice, 2);
     }
 
     #[test]
     fn test_conv_from_u8() {
-        let subservice: Subservice = 2.try_into().unwrap();
-        assert_eq!(subservice, Subservice::TmLowSeverityReport);
+        let subservice: MessageSubtypeId = 2.try_into().unwrap();
+        assert_eq!(subservice, MessageSubtypeId::TmLowSeverityReport);
     }
 
     #[test]
     fn test_conv_fails() {
-        let conversion = Subservice::try_from(9);
+        let conversion = MessageSubtypeId::try_from(9);
         assert!(conversion.is_err());
         let err = conversion.unwrap_err();
         assert_eq!(err.number, 9);

src/ecss/hk.rs

@@ -3,31 +3,49 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// Housekeeping service subtype ID.
 #[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
-pub enum Subservice {
+pub enum MessageSubtypeId {
     // Regular HK
+    /// Telecommand - Create Housekeeping Report Structure.
     TcCreateHkReportStructure = 1,
+    /// Telecommand - Delete HK report structures.
     TcDeleteHkReportStructures = 3,
+    /// Telecommand - Enable HK generation.
     TcEnableHkGeneration = 5,
+    /// Telecommand - Disable HK generation.
     TcDisableHkGeneration = 6,
+    /// Telecommand - Report HK report structures.
     TcReportHkReportStructures = 9,
+    /// Telemetry - HK report.
     TmHkPacket = 25,
+    /// Telecommand - Generate one-shot report.
     TcGenerateOneShotHk = 27,
+    /// Telecommand - Modify collection interval.
     TcModifyHkCollectionInterval = 31,
 
-    // Diagnostics HK
+    /// Telecommand - Create diagnostics report structures.
     TcCreateDiagReportStructure = 2,
+    /// Telecommand - Delete diagnostics report structures.
     TcDeleteDiagReportStructures = 4,
+    /// Telecommand - Enable diagnostics generation.
     TcEnableDiagGeneration = 7,
+    /// Telecommand - Disable diagnostics generation.
     TcDisableDiagGeneration = 8,
+    /// Telemetry - HK structures report.
     TmHkStructuresReport = 10,
+    /// Telecommand - Report diagnostics report structures.
     TcReportDiagReportStructures = 11,
+    /// Telemetry - Diagnostics report structures.
     TmDiagStructuresReport = 12,
+    /// Telemetry - Diagnostics packet.
     TmDiagPacket = 26,
+    /// Telecommand - Generate one-shot diagnostics report.
     TcGenerateOneShotDiag = 28,
+    /// Telecommand - Modify diagnostics interval report.
     TcModifyDiagCollectionInterval = 32,
 }
 
@@ -37,25 +55,26 @@ mod tests {
     #[test]
     fn test_try_from_u8() {
         let hk_report_subservice_raw = 25;
-        let hk_report: Subservice = Subservice::try_from(hk_report_subservice_raw).unwrap();
-        assert_eq!(hk_report, Subservice::TmHkPacket);
+        let hk_report: MessageSubtypeId =
+            MessageSubtypeId::try_from(hk_report_subservice_raw).unwrap();
+        assert_eq!(hk_report, MessageSubtypeId::TmHkPacket);
     }
 
     #[test]
     fn test_into_u8() {
-        let hk_report_raw: u8 = Subservice::TmHkPacket.into();
+        let hk_report_raw: u8 = MessageSubtypeId::TmHkPacket.into();
         assert_eq!(hk_report_raw, 25);
     }
 
     #[test]
     fn test_partial_eq() {
-        let hk_report_raw = Subservice::TmHkPacket;
-        assert_ne!(hk_report_raw, Subservice::TcGenerateOneShotHk);
-        assert_eq!(hk_report_raw, Subservice::TmHkPacket);
+        let hk_report_raw = MessageSubtypeId::TmHkPacket;
+        assert_ne!(hk_report_raw, MessageSubtypeId::TcGenerateOneShotHk);
+        assert_eq!(hk_report_raw, MessageSubtypeId::TmHkPacket);
     }
     #[test]
     fn test_copy_clone() {
-        let hk_report = Subservice::TmHkPacket;
+        let hk_report = MessageSubtypeId::TmHkPacket;
         let hk_report_copy = hk_report;
         assert_eq!(hk_report, hk_report_copy);
     }

src/ecss/mod.rs

@@ -3,94 +3,105 @@
 //!
 //! You can find the PUS telecommand types in the [tc] module and the the PUS telemetry
 //! types inside the [tm] module.
-use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
+use crate::{
+    crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE},
+    ByteConversionError, CcsdsPacket,
+};
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
-use core::fmt::{Debug, Display, Formatter};
+use arbitrary_int::u4;
+use core::fmt::Debug;
 use core::mem::size_of;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-#[cfg(feature = "std")]
-use std::error::Error;
 
 pub mod event;
 pub mod hk;
 pub mod scheduling;
 pub mod tc;
+pub mod tc_pus_a;
 pub mod tm;
+pub mod tm_pus_a;
 pub mod verification;
 
+/// Type alias for the CRC16 type.
 pub type CrcType = u16;
 
+/// Standard PUS service IDs.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 #[non_exhaustive]
 pub enum PusServiceId {
-    /// Service 1
+    /// Service 1 Verification
     Verification = 1,
-    /// Service 2
+    /// Service 2 Device Access
     DeviceAccess = 2,
-    /// Service 3
+    /// Service 3 Housekeeping
     Housekeeping = 3,
-    /// Service 4
+    /// Service 4 Parameter Statistics
     ParameterStatistics = 4,
-    /// Service 5
+    /// Service 5 Event
     Event = 5,
-    /// Service 6
+    /// Service 6 Memory Management
     MemoryManagement = 6,
-    /// Service 8
+    /// Service 8 Action
     Action = 8,
-    /// Service 9
+    /// Service 9 Time Management
     TimeManagement = 9,
-    /// Service 11
+    /// Service 11 Scheduling
     Scheduling = 11,
-    /// Service 12
+    /// Service 12 On-Board Monitoring
     OnBoardMonitoring = 12,
-    /// Service 13
+    /// Service 13 Large Packet Transfer
     LargePacketTransfer = 13,
-    /// Service 14
+    /// Service 14 Real-Time Forwarding Control
     RealTimeForwardingControl = 14,
-    /// Service 15
+    /// Service 15 Storage And Retrival
     StorageAndRetrival = 15,
-    /// Service 17
+    /// Service 17 Test
     Test = 17,
-    /// Service 18
+    /// Service 18 Operations And Procedures
     OpsAndProcedures = 18,
-    /// Service 19
+    /// Service 19 Event Action
     EventAction = 19,
-    /// Service 20
+    /// Service 20 Parameter
     Parameter = 20,
-    /// Service 21
+    /// Service 21 Request Sequencing
     RequestSequencing = 21,
-    /// Service 22
+    /// Service 22 Position Based Scheduling
     PositionBasedScheduling = 22,
-    /// Service 23
+    /// Service 23 File Management
     FileManagement = 23,
 }
 
 /// All PUS versions. Only PUS C is supported by this library.
-#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[derive(PartialEq, Eq, Debug, num_enum::TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[bitbybit::bitenum(u4, exhaustive = false)]
+#[repr(u8)]
 #[non_exhaustive]
 pub enum PusVersion {
+    /// ESA PUS
     EsaPus = 0,
+    /// PUS A
     PusA = 1,
+    /// PUS C
     PusC = 2,
-    Invalid = 0b1111,
 }
 
-impl TryFrom<u8> for PusVersion {
-    type Error = ();
+impl TryFrom<u4> for PusVersion {
+    type Error = u4;
 
-    fn try_from(value: u8) -> Result<Self, Self::Error> {
+    fn try_from(value: u4) -> Result<Self, Self::Error> {
         match value {
-            x if x == PusVersion::EsaPus as u8 => Ok(PusVersion::EsaPus),
-            x if x == PusVersion::PusA as u8 => Ok(PusVersion::PusA),
-            x if x == PusVersion::PusC as u8 => Ok(PusVersion::PusC),
-            _ => Err(()),
+            x if x == PusVersion::EsaPus.raw_value() => Ok(PusVersion::EsaPus),
+            x if x == PusVersion::PusA.raw_value() => Ok(PusVersion::PusA),
+            x if x == PusVersion::PusC.raw_value() => Ok(PusVersion::PusC),
+            _ => Err(value),
         }
     }
 }
@@ -98,44 +109,70 @@ impl TryFrom<u8> for PusVersion {
 /// ECSS Packet Type Codes (PTC)s.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum PacketTypeCodes {
+    /// Boolean.
     Boolean = 1,
+    /// Enumerated.
     Enumerated = 2,
+    /// Unsigned Integer.
     UnsignedInt = 3,
+    /// Signed Integer.
     SignedInt = 4,
+    /// Real (floating point).
     Real = 5,
+    /// Bit string.
     BitString = 6,
+    /// Octet (byte) string.
     OctetString = 7,
+    /// Character string.
     CharString = 8,
+    /// Absolute time.
     AbsoluteTime = 9,
+    /// Relative time.
     RelativeTime = 10,
+    /// Deduced.
     Deduced = 11,
+    /// Packet.
     Packet = 12,
 }
 
+/// Type alias for the ECSS Packet Type Codes (PTC)s.
 pub type Ptc = PacketTypeCodes;
 
 /// ECSS Packet Field Codes (PFC)s for the unsigned [Ptc].
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum PfcUnsigned {
+    /// 1 byte.
     OneByte = 4,
+    /// 12 bits.
     TwelveBits = 8,
+    /// 2 bytes.
     TwoBytes = 12,
+    /// 3 bytes.
     ThreeBytes = 13,
+    /// 4 bytes.
     FourBytes = 14,
+    /// 6 bytes.
     SixBytes = 15,
+    /// 8 bytes.
     EightBytes = 16,
+    /// 1 bit.
     OneBit = 17,
+    /// 2 bits.
     TwoBits = 18,
+    /// 3 bits.
     ThreeBits = 19,
 }
 
 /// ECSS Packet Field Codes (PFC)s for the real (floating point) [Ptc].
 #[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
 pub enum PfcReal {
     /// 4 octets simple precision format (IEEE)
@@ -148,62 +185,76 @@ pub enum PfcReal {
     DoubleMilStd = 4,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+/// Generic PUS error.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PusError {
-    VersionNotSupported(PusVersion),
+    /// PUS version is not supported.
+    #[error("PUS version {0:?} not supported")]
+    VersionNotSupported(u4),
+    /// Checksum failure.
+    #[error("checksum verification for crc16 {0:#06x} failed")]
     ChecksumFailure(u16),
     /// CRC16 needs to be calculated first
-    CrcCalculationMissing,
-    ByteConversion(ByteConversionError),
+    //#[error("crc16 was not calculated")]
+    //CrcCalculationMissing,
+    #[error("pus error: {0}")]
+    ByteConversion(#[from] ByteConversionError),
 }
 
-impl Display for PusError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            PusError::VersionNotSupported(v) => {
-                write!(f, "PUS version {v:?} not supported")
-            }
-            PusError::ChecksumFailure(crc) => {
-                write!(f, "checksum verification for crc16 {crc:#06x} failed")
-            }
-            PusError::CrcCalculationMissing => {
-                write!(f, "crc16 was not calculated")
-            }
-            PusError::ByteConversion(e) => {
-                write!(f, "pus error: {e}")
-            }
+/// Message type ID field.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct MessageTypeId {
+    /// Service type ID.
+    pub type_id: u8,
+    /// Subtype ID.
+    pub subtype_id: u8,
+}
+
+impl MessageTypeId {
+    /// Generic constructor.
+    pub const fn new(type_id: u8, subtype_id: u8) -> Self {
+        Self {
+            type_id,
+            subtype_id,
         }
     }
 }
 
-#[cfg(feature = "std")]
-impl Error for PusError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        if let PusError::ByteConversion(e) = self {
-            return Some(e);
-        }
-        None
-    }
-}
-
-impl From<ByteConversionError> for PusError {
-    fn from(e: ByteConversionError) -> Self {
-        PusError::ByteConversion(e)
-    }
-}
-
 /// Generic trait to describe common attributes for both PUS Telecommands (TC) and PUS Telemetry
 /// (TM) packets. All PUS packets are also a special type of [CcsdsPacket]s.
 pub trait PusPacket: CcsdsPacket {
-    const PUS_VERSION: PusVersion = PusVersion::PusC;
+    /// PUS version.
+    fn pus_version(&self) -> Result<PusVersion, u4>;
 
-    fn pus_version(&self) -> PusVersion;
-    fn service(&self) -> u8;
-    fn subservice(&self) -> u8;
+    /// Message type ID.
+    fn message_type_id(&self) -> MessageTypeId;
+
+    /// Service type ID.
+    #[inline]
+    fn service_type_id(&self) -> u8 {
+        self.message_type_id().type_id
+    }
+
+    /// Message subtype ID.
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.message_type_id().subtype_id
+    }
+
+    /// User data field.
     fn user_data(&self) -> &[u8];
-    fn crc16(&self) -> Option<u16>;
+
+    /// CRC-16-CCITT checksum.
+    fn checksum(&self) -> Option<u16>;
+
+    /// The presence of the CRC-16-CCITT checksum is optional.
+    fn has_checksum(&self) -> bool {
+        self.checksum().is_some()
+    }
 }
 
 pub(crate) fn crc_from_raw_data(raw_data: &[u8]) -> Result<u16, ByteConversionError> {
@@ -230,17 +281,23 @@ pub(crate) fn user_data_from_raw(
     current_idx: usize,
     total_len: usize,
     slice: &[u8],
+    has_checksum: bool,
 ) -> Result<&[u8], ByteConversionError> {
-    match current_idx {
-        _ if current_idx > total_len - 2 => Err(ByteConversionError::FromSliceTooSmall {
-            found: total_len - 2,
-            expected: current_idx,
-        }),
-        _ => Ok(&slice[current_idx..total_len - 2]),
+    if has_checksum {
+        if current_idx > total_len - 2 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: total_len - 2,
+                expected: current_idx,
+            });
+        }
+        Ok(&slice[current_idx..total_len - 2])
+    } else {
+        Ok(&slice[current_idx..total_len])
     }
 }
 
-pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
+/// Verify the CRC16 of a raw packet and return a [PusError] on failure.
+pub fn verify_crc16_ccitt_false_from_raw_to_pus_error(
     raw_data: &[u8],
     crc16: u16,
 ) -> Result<(), PusError> {
@@ -249,7 +306,19 @@ pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
         .ok_or(PusError::ChecksumFailure(crc16))
 }
 
-pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
+/// Verify the CRC16 of a raw packet using a table-less implementation and return a [PusError] on
+/// failure.
+pub fn verify_crc16_ccitt_false_from_raw_to_pus_error_no_table(
+    raw_data: &[u8],
+    crc16: u16,
+) -> Result<(), PusError> {
+    verify_crc16_ccitt_false_from_raw_no_table(raw_data)
+        .then_some(())
+        .ok_or(PusError::ChecksumFailure(crc16))
+}
+
+/// Verify the CRC16 of a raw packet.
+pub fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
     let mut digest = CRC_CCITT_FALSE.digest();
     digest.update(raw_data);
     if digest.finalize() == 0 {
@@ -258,28 +327,28 @@ pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
     false
 }
 
-macro_rules! ccsds_impl {
-    () => {
-        delegate!(to self.sp_header {
-            #[inline]
-            fn ccsds_version(&self) -> u8;
-            #[inline]
-            fn packet_id(&self) -> crate::PacketId;
-            #[inline]
-            fn psc(&self) -> crate::PacketSequenceCtrl;
-            #[inline]
-            fn data_len(&self) -> u16;
-        });
+/// Verify the CRC16 of a raw packet, using the table-less implementation.
+pub fn verify_crc16_ccitt_false_from_raw_no_table(raw_data: &[u8]) -> bool {
+    let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
+    digest.update(raw_data);
+    if digest.finalize() == 0 {
+        return true;
     }
+    false
 }
 
 macro_rules! sp_header_impls {
     () => {
         delegate!(to self.sp_header {
+            /// Set the CCSDS APID.
             #[inline]
-            pub fn set_apid(&mut self, apid: u16) -> bool;
+            pub fn set_apid(&mut self, apid: u11);
+
+            /// Set the CCSDS sequence count.
             #[inline]
-            pub fn set_seq_count(&mut self, seq_count: u16) -> bool;
+            pub fn set_seq_count(&mut self, seq_count: u14);
+
+            /// Set the CCSDS sequence flags.
             #[inline]
             pub fn set_seq_flags(&mut self, seq_flag: SequenceFlags);
         });
@@ -287,7 +356,6 @@ macro_rules! sp_header_impls {
 }
 
 use crate::util::{GenericUnsignedByteField, ToBeBytes, UnsignedEnum};
-pub(crate) use ccsds_impl;
 pub(crate) use sp_header_impls;
 
 /// Generic trait for ECSS enumeration which consist of a PFC field denoting their bit length
@@ -299,27 +367,28 @@ pub trait EcssEnumeration: UnsignedEnum {
     fn pfc(&self) -> u8;
 }
 
+/// Extension trait for [EcssEnumeration] which adds common trait bounds.
 pub trait EcssEnumerationExt: EcssEnumeration + Debug + Copy + Clone + PartialEq + Eq {}
 
+/// ECSS enumerated type wrapper.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct GenericEcssEnumWrapper<TYPE: Copy + Into<u64>> {
-    field: GenericUnsignedByteField<TYPE>,
-}
+pub struct GenericEcssEnumWrapper<TYPE: Copy + Into<u64>>(GenericUnsignedByteField<TYPE>);
 
 impl<TYPE: Copy + Into<u64>> GenericEcssEnumWrapper<TYPE> {
+    /// Returns [PacketTypeCodes::Enumerated].
     pub const fn ptc() -> PacketTypeCodes {
         PacketTypeCodes::Enumerated
     }
 
-    pub const fn value_typed(&self) -> TYPE {
-        self.field.value_typed()
+    /// Value.
+    pub const fn value(&self) -> TYPE {
+        self.0.value()
     }
 
-    pub fn new(val: TYPE) -> Self {
-        Self {
-            field: GenericUnsignedByteField::new(val),
-        }
+    /// Generic constructor.
+    pub const fn new(val: TYPE) -> Self {
+        Self(GenericUnsignedByteField::new(val))
     }
 }
 
@@ -329,11 +398,11 @@ impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericEcssEnumWrapper
     }
 
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
-        self.field.write_to_be_bytes(buf)
+        self.0.write_to_be_bytes(buf)
     }
 
-    fn value(&self) -> u64 {
-        self.field.value()
+    fn value_raw(&self) -> u64 {
+        self.0.value().into()
     }
 }
 
@@ -357,11 +426,12 @@ impl<T: Copy + Into<u64>> From<T> for GenericEcssEnumWrapper<T> {
 macro_rules! generic_ecss_enum_typedefs_and_from_impls {
     ($($ty:ty => $Enum:ident),*) => {
         $(
+            /// Type alias for ECSS enumeration wrapper around `$ty`
             pub type $Enum = GenericEcssEnumWrapper<$ty>;
 
             impl From<$Enum> for $ty {
                 fn from(value: $Enum) -> Self {
-                    value.value_typed()
+                    value.value()
                 }
             }
         )*
@@ -381,8 +451,48 @@ generic_ecss_enum_typedefs_and_from_impls! {
 /// byte representation. This is especially useful for generic abstractions which depend only
 /// on the serialization of those packets.
 pub trait WritablePusPacket {
+    /// The length here also includes the CRC length.
     fn len_written(&self) -> usize;
-    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+
+    /// Checksum generation is enabled for the packet.
+    fn has_checksum(&self) -> bool;
+
+    /// Writes the packet to the given slice without writing the CRC checksum.
+    ///
+    /// The returned size is the written size WITHOUT the CRC checksum.
+    /// If the checksum generation is disabled, this function is identical to the APIs which
+    /// generate a checksum.
+    fn write_to_bytes_no_checksum(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+
+    /// First uses [Self::write_to_bytes_no_checksum] to write the packet to the given slice and
+    /// then uses the [CRC_CCITT_FALSE] to calculate the CRC and write it to the slice if the
+    /// packet is configured to include a checksum.
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
+        let mut curr_idx = self.write_to_bytes_no_checksum(slice)?;
+        if self.has_checksum() {
+            let mut digest = CRC_CCITT_FALSE.digest();
+            digest.update(&slice[0..curr_idx]);
+            slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+            curr_idx += 2;
+        }
+        Ok(curr_idx)
+    }
+
+    /// First uses [Self::write_to_bytes_no_checksum] to write the packet to the given slice and then
+    /// uses the [CRC_CCITT_FALSE_NO_TABLE] to calculate the CRC and write it to the slice if
+    /// the paket is configured to include a checksum.
+    fn write_to_bytes_checksum_no_table(&self, slice: &mut [u8]) -> Result<usize, PusError> {
+        let mut curr_idx = self.write_to_bytes_no_checksum(slice)?;
+        if self.has_checksum() {
+            let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
+            digest.update(&slice[0..curr_idx]);
+            slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+            curr_idx += 2;
+        }
+        Ok(curr_idx)
+    }
+
+    /// Converts the packet into an owned [alloc::vec::Vec].
     #[cfg(feature = "alloc")]
     fn to_vec(&self) -> Result<Vec<u8>, PusError> {
         // This is the correct way to do this. See
@@ -394,6 +504,26 @@ pub trait WritablePusPacket {
     }
 }
 
+/// PUS packet creator configuration.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct CreatorConfig {
+    /// Set the CCSDS data length field on construction.
+    pub set_ccsds_len: bool,
+    /// CRC-16-CCITT Checksum is present.
+    pub has_checksum: bool,
+}
+
+impl Default for CreatorConfig {
+    fn default() -> Self {
+        Self {
+            set_ccsds_len: true,
+            has_checksum: true,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use alloc::string::ToString;
@@ -417,7 +547,7 @@ mod tests {
             .expect("To byte conversion of u8 failed");
         assert_eq!(buf[1], 1);
         assert_eq!(my_enum.value(), 1);
-        assert_eq!(my_enum.value_typed(), 1);
+        assert_eq!(my_enum.value(), 1);
         let enum_as_u8: u8 = my_enum.into();
         assert_eq!(enum_as_u8, 1);
         let vec = my_enum.to_vec();
@@ -436,7 +566,7 @@ mod tests {
         assert_eq!(buf[1], 0x1f);
         assert_eq!(buf[2], 0x2f);
         assert_eq!(my_enum.value(), 0x1f2f);
-        assert_eq!(my_enum.value_typed(), 0x1f2f);
+        assert_eq!(my_enum.value(), 0x1f2f);
         let enum_as_raw: u16 = my_enum.into();
         assert_eq!(enum_as_raw, 0x1f2f);
         let vec = my_enum.to_vec();
@@ -473,7 +603,7 @@ mod tests {
         assert_eq!(buf[3], 0x3f);
         assert_eq!(buf[4], 0x4f);
         assert_eq!(my_enum.value(), 0x1f2f3f4f);
-        assert_eq!(my_enum.value_typed(), 0x1f2f3f4f);
+        assert_eq!(my_enum.value(), 0x1f2f3f4f);
         let enum_as_raw: u32 = my_enum.into();
         assert_eq!(enum_as_raw, 0x1f2f3f4f);
         let vec = my_enum.to_vec();
@@ -511,7 +641,7 @@ mod tests {
         assert_eq!(buf[6], 0x4f);
         assert_eq!(buf[7], 0x5f);
         assert_eq!(my_enum.value(), 0x1f2f3f4f5f);
-        assert_eq!(my_enum.value_typed(), 0x1f2f3f4f5f);
+        assert_eq!(my_enum.value(), 0x1f2f3f4f5f);
         let enum_as_raw: u64 = my_enum.into();
         assert_eq!(enum_as_raw, 0x1f2f3f4f5f);
         assert_eq!(u64::from_be_bytes(buf), 0x1f2f3f4f5f);
@@ -521,9 +651,10 @@ mod tests {
 
     #[test]
     fn test_pus_error_display() {
-        let unsupport_version = PusError::VersionNotSupported(super::PusVersion::EsaPus);
+        let unsupport_version =
+            PusError::VersionNotSupported(super::PusVersion::EsaPus.raw_value());
         let write_str = unsupport_version.to_string();
-        assert_eq!(write_str, "PUS version EsaPus not supported")
+        assert_eq!(write_str, "PUS version 0 not supported")
     }
 
     #[test]
@@ -557,8 +688,8 @@ mod tests {
     #[test]
     fn test_pus_error_eq_impl() {
         assert_eq!(
-            PusError::VersionNotSupported(PusVersion::EsaPus),
-            PusError::VersionNotSupported(PusVersion::EsaPus)
+            PusError::VersionNotSupported(PusVersion::EsaPus.raw_value()),
+            PusError::VersionNotSupported(PusVersion::EsaPus.raw_value())
         );
     }
 

src/ecss/scheduling.rs

@@ -3,53 +3,85 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// Scheduling service subtype ID.
 #[derive(Debug, PartialEq, Eq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
-pub enum Subservice {
+pub enum MessageSubtypeId {
     // Core subservices
+    /// Telecommand - Enable scheduling.
     TcEnableScheduling = 1,
+    /// Telecommand - Disable scheduling.
     TcDisableScheduling = 2,
+    /// Telecommand - Reset scheduling.
     TcResetScheduling = 3,
+    /// Telecommand - Insert activity.
     TcInsertActivity = 4,
+    /// Telecommand - Delete activity by request ID.
     TcDeleteActivityByRequestId = 5,
+    /// Telecommand - Delete activity by filter.
     TcDeleteActivitiesByFilter = 6,
 
     // Time shift subservices
+    /// Telecommand - Time shift activity by request ID.
     TcTimeShiftActivityWithRequestId = 7,
+    /// Telecommand - Time shift activity by filter.
     TcTimeShiftActivitiesByFilter = 8,
+    /// Telecommand - Time shift all.
     TcTimeShiftAll = 15,
 
     // Reporting subservices
+    /// Telecommand - Detail report by request ID.
     TcDetailReportByRequestId = 9,
+    /// Telemetry - Detail report.
     TmDetailReport = 10,
+    /// Telecommand - Detail report by filter.
     TcDetailReportByFilter = 11,
+    /// Telecommand - Summary report by request ID.
     TcSummaryReportByRequestId = 12,
+    /// Telemetry - Summary report.
     TmSummaryReport = 13,
+    /// Telecommand - Summary report by filter.
     TcSummaryReportByFilter = 14,
+    /// Telecommand - Detail report all.
     TcDetailReportAll = 16,
+    /// Telecommand - Summary report all.
     TcSummaryReportAll = 17,
 
     // Subschedule subservices
+    /// Telecommand - Report subschedule status.
     TcReportSubscheduleStatus = 18,
+    /// Telemetry - Subschedule status report.
     TmReportSubscheduleStatus = 19,
+    /// Telecommand - Enable subschedule.
     TcEnableSubschedule = 20,
+    /// Telecommand - Disable subschedule.
     TcDisableSubschedule = 21,
 
     // Group subservices
+    /// Telecommand - Create schedule group.
     TcCreateScheduleGroup = 22,
+    /// Telecommand - Delete schedule group.
     TcDeleteScheduleGroup = 23,
+    /// Telecommand - Enable schedule group.
     TcEnableScheduleGroup = 24,
+    /// Telecommand - Disable schedule group.
     TcDisableScheduleGroup = 25,
+    /// Telecommand - Report all group status.
     TcReportAllGroupsStatus = 26,
+    /// Telemetry - All group status report.
     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 = "defmt", derive(defmt::Format))]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum SchedStatus {
+    /// Scheduling disabled.
     Disabled = 0,
+    /// Scheduling enabled.
     Enabled = 1,
 }
 
@@ -66,11 +98,16 @@ impl From<bool> for SchedStatus {
 
 /// Time window types as specified in  ECSS-E-ST-70-41C 8.11.3
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum TimeWindowType {
+    /// Select all.
     SelectAll = 0,
+    /// From time tag to time tag.
     TimeTagToTimeTag = 1,
+    /// Starting from a time tag.
     FromTimeTag = 2,
+    /// Until a time tag.
     ToTimeTag = 3,
 }
 
@@ -96,20 +133,20 @@ mod tests {
 
     #[test]
     fn test_conv_into_u8() {
-        let subservice: u8 = Subservice::TcCreateScheduleGroup.into();
+        let subservice: u8 = MessageSubtypeId::TcCreateScheduleGroup.into();
         assert_eq!(subservice, 22);
     }
 
     #[test]
     fn test_conv_from_u8() {
-        let subservice: Subservice = 22u8.try_into().unwrap();
-        assert_eq!(subservice, Subservice::TcCreateScheduleGroup);
+        let subservice: MessageSubtypeId = 22u8.try_into().unwrap();
+        assert_eq!(subservice, MessageSubtypeId::TcCreateScheduleGroup);
     }
 
     #[test]
     #[cfg(feature = "serde")]
     fn test_serde_subservice_id() {
-        generic_serde_test(Subservice::TcEnableScheduling);
+        generic_serde_test(MessageSubtypeId::TcEnableScheduling);
     }
 
     #[test]

src/ecss/verification.rs

@@ -3,17 +3,27 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// Message subtype ID.
 #[derive(Debug, Eq, PartialEq, Copy, Clone, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[repr(u8)]
-pub enum Subservice {
+pub enum MessageSubtypeId {
+    /// Telemetry - Acceptance success.
     TmAcceptanceSuccess = 1,
+    /// Telemetry - Acceptance failure.
     TmAcceptanceFailure = 2,
+    /// Telemetry - Start success.
     TmStartSuccess = 3,
+    /// Telemetry - Start failure.
     TmStartFailure = 4,
+    /// Telemetry - Step success.
     TmStepSuccess = 5,
+    /// Telemetry - Step failure.
     TmStepFailure = 6,
+    /// Telemetry - Completion success.
     TmCompletionSuccess = 7,
+    /// Telemetry - Completion failure.
     TmCompletionFailure = 8,
 }
 
@@ -23,13 +33,13 @@ mod tests {
 
     #[test]
     fn test_conv_into_u8() {
-        let subservice: u8 = Subservice::TmCompletionSuccess.into();
+        let subservice: u8 = MessageSubtypeId::TmCompletionSuccess.into();
         assert_eq!(subservice, 7);
     }
 
     #[test]
     fn test_conv_from_u8() {
-        let subservice: Subservice = 7.try_into().unwrap();
-        assert_eq!(subservice, Subservice::TmCompletionSuccess);
+        let subservice: MessageSubtypeId = 7.try_into().unwrap();
+        assert_eq!(subservice, MessageSubtypeId::TmCompletionSuccess);
     }
 }

src/seq_count.rs

@@ -0,0 +1,473 @@
+//! # Sequence counter module.
+//!
+//! CCSDS and ECSS packet standard oftentimes use sequence counters, for example to allow detecting
+//! packet gaps. This module provides basic abstractions and helper components to implement
+//! sequence counters.
+use crate::MAX_SEQ_COUNT;
+use arbitrary_int::traits::Integer;
+use core::cell::Cell;
+use paste::paste;
+
+/// Core trait for objects which can provide a sequence count.
+///
+/// The core functions are not mutable on purpose to allow easier usage with
+/// static structs when using the interior mutability pattern. This can be achieved by using
+/// [Cell], [core::cell::RefCell] or atomic types.
+pub trait SequenceCounter {
+    /// Raw type of the counter.
+    type Raw: Into<u64>;
+
+    /// Bit width of the counter.
+    const MAX_BIT_WIDTH: usize;
+
+    /// Get the current sequence count value.
+    fn get(&self) -> Self::Raw;
+
+    /// Increment the sequence count by one.
+    fn increment(&self);
+
+    /// Increment the sequence count by one, mutable API.
+    fn increment_mut(&mut self) {
+        self.increment();
+    }
+
+    /// Get the current sequence count value and increment the counter by one.
+    fn get_and_increment(&self) -> Self::Raw {
+        let val = self.get();
+        self.increment();
+        val
+    }
+
+    /// Get the current sequence count value and increment the counter by one, mutable API.
+    fn get_and_increment_mut(&mut self) -> Self::Raw {
+        self.get_and_increment()
+    }
+}
+
+/// Simple sequence counter which wraps at ´T::MAX´.
+#[derive(Clone)]
+pub struct SequenceCounterSimple<T: Copy> {
+    seq_count: Cell<T>,
+    // The maximum value
+    max_val: T,
+}
+
+macro_rules! impl_for_primitives {
+    ($($ty: ident,)+) => {
+        $(
+            paste! {
+                impl SequenceCounterSimple<$ty> {
+                    /// Constructor with a custom maximum value.
+                    pub fn [<new_custom_max_val_ $ty>](max_val: $ty) -> Self {
+                        Self {
+                            seq_count: Cell::new(0),
+                            max_val,
+                        }
+                    }
+
+                    /// Generic constructor.
+                    pub fn [<new_ $ty>]() -> Self {
+                        Self {
+                            seq_count: Cell::new(0),
+                            max_val: $ty::MAX
+                        }
+                    }
+                }
+
+                impl Default for SequenceCounterSimple<$ty> {
+                    fn default() -> Self {
+                        Self::[<new_ $ty>]()
+                    }
+                }
+
+                impl SequenceCounter for SequenceCounterSimple<$ty> {
+                    type Raw = $ty;
+                    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                    fn get(&self) -> Self::Raw {
+                        self.seq_count.get()
+                    }
+
+                    fn increment(&self) {
+                        self.get_and_increment();
+                    }
+
+                    fn get_and_increment(&self) -> Self::Raw {
+                        let curr_count = self.seq_count.get();
+
+                        if curr_count == self.max_val {
+                            self.seq_count.set(0);
+                        } else {
+                            self.seq_count.set(curr_count + 1);
+                        }
+                        curr_count
+                    }
+                }
+            }
+        )+
+    }
+}
+
+impl_for_primitives!(u8, u16, u32, u64,);
+
+/// This is a sequence count provider which wraps around at [MAX_SEQ_COUNT].
+#[derive(Clone)]
+pub struct SequenceCounterCcsdsSimple {
+    provider: SequenceCounterSimple<u16>,
+}
+
+impl Default for SequenceCounterCcsdsSimple {
+    fn default() -> Self {
+        Self {
+            provider: SequenceCounterSimple::new_custom_max_val_u16(MAX_SEQ_COUNT.as_u16()),
+        }
+    }
+}
+
+impl SequenceCounter for SequenceCounterCcsdsSimple {
+    type Raw = u16;
+    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+    delegate::delegate! {
+        to self.provider {
+            fn get(&self) -> u16;
+            fn increment(&self);
+            fn get_and_increment(&self) -> u16;
+        }
+    }
+}
+
+#[cfg(target_has_atomic = "8")]
+impl SequenceCounter for core::sync::atomic::AtomicU8 {
+    type Raw = u8;
+
+    const MAX_BIT_WIDTH: usize = 8;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(target_has_atomic = "16")]
+impl SequenceCounter for core::sync::atomic::AtomicU16 {
+    type Raw = u16;
+
+    const MAX_BIT_WIDTH: usize = 16;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(target_has_atomic = "32")]
+impl SequenceCounter for core::sync::atomic::AtomicU32 {
+    type Raw = u32;
+
+    const MAX_BIT_WIDTH: usize = 32;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(target_has_atomic = "64")]
+impl SequenceCounter for core::sync::atomic::AtomicU64 {
+    type Raw = u64;
+
+    const MAX_BIT_WIDTH: usize = 64;
+
+    fn get(&self) -> Self::Raw {
+        self.load(core::sync::atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(feature = "portable-atomic")]
+impl SequenceCounter for portable_atomic::AtomicU8 {
+    type Raw = u8;
+
+    const MAX_BIT_WIDTH: usize = 8;
+
+    fn get(&self) -> Self::Raw {
+        self.load(portable_atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(feature = "portable-atomic")]
+impl SequenceCounter for portable_atomic::AtomicU16 {
+    type Raw = u16;
+
+    const MAX_BIT_WIDTH: usize = 16;
+
+    fn get(&self) -> Self::Raw {
+        self.load(portable_atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(feature = "portable-atomic")]
+impl SequenceCounter for portable_atomic::AtomicU32 {
+    type Raw = u32;
+
+    const MAX_BIT_WIDTH: usize = 32;
+
+    fn get(&self) -> Self::Raw {
+        self.load(portable_atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+}
+
+#[cfg(feature = "portable-atomic")]
+impl SequenceCounter for portable_atomic::AtomicU64 {
+    type Raw = u64;
+
+    const MAX_BIT_WIDTH: usize = 64;
+
+    fn get(&self) -> Self::Raw {
+        self.load(portable_atomic::Ordering::Relaxed)
+    }
+
+    fn increment(&self) {
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+}
+
+impl<T: SequenceCounter + ?Sized> SequenceCounter for &T {
+    type Raw = T::Raw;
+    const MAX_BIT_WIDTH: usize = T::MAX_BIT_WIDTH;
+
+    fn get(&self) -> Self::Raw {
+        (**self).get()
+    }
+
+    fn increment(&self) {
+        (**self).increment()
+    }
+}
+
+#[cfg(any(
+    target_has_atomic = "8",
+    target_has_atomic = "16",
+    target_has_atomic = "32",
+    target_has_atomic = "64"
+))]
+macro_rules! sync_clonable_seq_counter_impl {
+    ($ty: ident) => {
+        paste::paste! {
+            /// This can be used if a custom wrap value is required when using a thread-safe
+            /// atomic based sequence counter.
+            #[derive(Debug)]
+            pub struct [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                seq_count: core::sync::atomic::[<Atomic $ty:upper>],
+                max_val: $ty,
+            }
+
+            impl [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                /// Generic constructor.
+                pub fn new(max_val: $ty) -> Self {
+                    Self {
+                        seq_count: core::sync::atomic::[<Atomic $ty:upper>]::new(0),
+                        max_val,
+                    }
+                }
+            }
+
+            impl SequenceCounter for [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                type Raw = $ty;
+                const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                fn get(&self) -> $ty {
+                    self.seq_count.load(core::sync::atomic::Ordering::Relaxed)
+                }
+
+                fn increment(&self) {
+                    self.get_and_increment();
+                }
+
+                fn get_and_increment(&self) -> $ty {
+                    self.seq_count.fetch_update(
+                        core::sync::atomic::Ordering::Relaxed,
+                        core::sync::atomic::Ordering::Relaxed,
+                        |cur| {
+                            // compute the next value, wrapping at MAX_VAL
+                            let next = if cur == self.max_val { 0 } else { cur + 1 };
+                            Some(next)
+                        },
+                    ).unwrap()
+                }
+            }
+        }
+    };
+}
+
+#[cfg(target_has_atomic = "8")]
+sync_clonable_seq_counter_impl!(u8);
+#[cfg(target_has_atomic = "16")]
+sync_clonable_seq_counter_impl!(u16);
+#[cfg(target_has_atomic = "32")]
+sync_clonable_seq_counter_impl!(u32);
+#[cfg(target_has_atomic = "64")]
+sync_clonable_seq_counter_impl!(u64);
+
+#[cfg(test)]
+mod tests {
+    use core::sync::atomic::{AtomicU16, AtomicU32, AtomicU64, AtomicU8};
+
+    use crate::seq_count::{
+        SequenceCounter, SequenceCounterCcsdsSimple, SequenceCounterSimple,
+        SequenceCounterSyncCustomWrapU8,
+    };
+    use crate::MAX_SEQ_COUNT;
+
+    #[test]
+    fn test_u8_counter() {
+        let u8_counter = SequenceCounterSimple::<u8>::default();
+        assert_eq!(u8_counter.get(), 0);
+        assert_eq!(u8_counter.get_and_increment(), 0);
+        assert_eq!(u8_counter.get_and_increment(), 1);
+        assert_eq!(u8_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_u8_counter_overflow() {
+        let u8_counter = SequenceCounterSimple::new_u8();
+        for _ in 0..256 {
+            u8_counter.increment();
+        }
+        assert_eq!(u8_counter.get(), 0);
+    }
+
+    #[test]
+    fn test_ccsds_counter() {
+        let ccsds_counter = SequenceCounterCcsdsSimple::default();
+        assert_eq!(ccsds_counter.get(), 0);
+        assert_eq!(ccsds_counter.get_and_increment(), 0);
+        assert_eq!(ccsds_counter.get_and_increment(), 1);
+        assert_eq!(ccsds_counter.get(), 2);
+    }
+
+    #[test]
+    fn test_ccsds_counter_overflow() {
+        let ccsds_counter = SequenceCounterCcsdsSimple::default();
+        for _ in 0..MAX_SEQ_COUNT.value() + 1 {
+            ccsds_counter.increment();
+        }
+        assert_eq!(ccsds_counter.get(), 0);
+    }
+
+    fn common_counter_test(seq_counter: &mut impl SequenceCounter) {
+        assert_eq!(seq_counter.get().into(), 0);
+        assert_eq!(seq_counter.get_and_increment().into(), 0);
+        assert_eq!(seq_counter.get_and_increment().into(), 1);
+        assert_eq!(seq_counter.get().into(), 2);
+        seq_counter.increment_mut();
+        assert_eq!(seq_counter.get().into(), 3);
+        assert_eq!(seq_counter.get_and_increment_mut().into(), 3);
+        assert_eq!(seq_counter.get().into(), 4);
+    }
+
+    #[test]
+    fn test_atomic_counter_u8() {
+        let mut sync_u8_counter = AtomicU8::new(0);
+        common_counter_test(&mut sync_u8_counter);
+    }
+
+    #[test]
+    fn test_atomic_counter_u16() {
+        let mut sync_u16_counter = AtomicU16::new(0);
+        common_counter_test(&mut sync_u16_counter);
+    }
+
+    #[test]
+    fn test_atomic_counter_u32() {
+        let mut sync_u32_counter = AtomicU32::new(0);
+        common_counter_test(&mut sync_u32_counter);
+    }
+
+    #[test]
+    fn test_atomic_counter_u64() {
+        let mut sync_u64_counter = AtomicU64::new(0);
+        common_counter_test(&mut sync_u64_counter);
+    }
+
+    #[test]
+    #[cfg(feature = "portable-atomic")]
+    fn test_portable_atomic_counter_u8() {
+        let mut sync_u8_counter = portable_atomic::AtomicU8::new(0);
+        common_counter_test(&mut sync_u8_counter);
+    }
+
+    #[test]
+    #[cfg(feature = "portable-atomic")]
+    fn test_portable_atomic_counter_u16() {
+        let mut sync_u16_counter = portable_atomic::AtomicU16::new(0);
+        common_counter_test(&mut sync_u16_counter);
+    }
+
+    #[test]
+    #[cfg(feature = "portable-atomic")]
+    fn test_portable_atomic_counter_u32() {
+        let mut sync_u32_counter = portable_atomic::AtomicU32::new(0);
+        common_counter_test(&mut sync_u32_counter);
+    }
+
+    #[test]
+    #[cfg(feature = "portable-atomic")]
+    fn test_portable_atomic_counter_u64() {
+        let mut sync_u64_counter = portable_atomic::AtomicU64::new(0);
+        common_counter_test(&mut sync_u64_counter);
+    }
+
+    fn common_overflow_test_u8(seq_counter: &impl SequenceCounter) {
+        for _ in 0..u8::MAX as u16 + 1 {
+            seq_counter.increment();
+        }
+        assert_eq!(seq_counter.get().into(), 0);
+    }
+
+    #[test]
+    fn test_atomic_u8_counter_overflow() {
+        let sync_u8_counter = AtomicU8::new(0);
+        common_overflow_test_u8(&sync_u8_counter);
+    }
+
+    #[test]
+    #[cfg(feature = "portable-atomic")]
+    fn test_portable_atomic_u8_counter_overflow() {
+        let sync_u8_counter = portable_atomic::AtomicU8::new(0);
+        common_overflow_test_u8(&sync_u8_counter);
+    }
+
+    #[test]
+    fn test_atomic_ref_counters_overflow_custom_max_val() {
+        let sync_u8_counter = SequenceCounterSyncCustomWrapU8::new(128);
+        for _ in 0..129 {
+            sync_u8_counter.increment();
+        }
+        assert_eq!(sync_u8_counter.get(), 0);
+    }
+}

src/time/ascii.rs

@@ -31,6 +31,7 @@ pub const FMT_STR_CODE_B_WITH_SIZE: (&str, usize) = ("%Y-%jT%T%.3f", 21);
 /// Three digits are used for the decimal fraction and a terminator is added at the end.
 pub const FMT_STR_CODE_B_TERMINATED_WITH_SIZE: (&str, usize) = ("%Y-%jT%T%.3fZ", 22);
 
+/// Functions requiring both [chrono] and [alloc] support.
 #[cfg(all(feature = "alloc", feature = "chrono"))]
 pub mod alloc_mod_chrono {
     use super::*;
@@ -71,7 +72,19 @@ mod tests {
     use std::format;
 
     #[test]
-    fn test_ascii_timestamp_a_unterminated() {
+    fn test_ascii_timestamp_a_unterminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
+        let stamp_formatter = generate_time_code_a(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 10);
+        assert_eq!(stamp.len(), FMT_STR_CODE_A_WITH_SIZE.1);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_a_unterminated_now() {
         let date = Utc::now();
         let stamp_formatter = generate_time_code_a(&date);
         let stamp = format!("{}", stamp_formatter);
@@ -82,7 +95,24 @@ mod tests {
     }
 
     #[test]
-    fn test_ascii_timestamp_a_terminated() {
+    fn test_ascii_timestamp_a_terminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
+        let stamp_formatter = generate_time_code_a_terminated(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 10);
+        let z_terminator = stamp.find('Z');
+        assert!(z_terminator.is_some());
+        assert_eq!(
+            z_terminator.unwrap(),
+            FMT_STR_CODE_A_TERMINATED_WITH_SIZE.1 - 1
+        );
+        assert_eq!(stamp.len(), FMT_STR_CODE_A_TERMINATED_WITH_SIZE.1);
+    }
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_a_terminated_now() {
         let date = Utc::now();
         let stamp_formatter = generate_time_code_a_terminated(&date);
         let stamp = format!("{}", stamp_formatter);
@@ -99,7 +129,19 @@ mod tests {
     }
 
     #[test]
-    fn test_ascii_timestamp_b_unterminated() {
+    fn test_ascii_timestamp_b_unterminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
+        let stamp_formatter = generate_time_code_b(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 8);
+        assert_eq!(stamp.len(), FMT_STR_CODE_B_WITH_SIZE.1);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_b_unterminated_now() {
         let date = Utc::now();
         let stamp_formatter = generate_time_code_b(&date);
         let stamp = format!("{}", stamp_formatter);
@@ -110,7 +152,25 @@ mod tests {
     }
 
     #[test]
-    fn test_ascii_timestamp_b_terminated() {
+    fn test_ascii_timestamp_b_terminated_epoch() {
+        let date = chrono::DateTime::UNIX_EPOCH;
+        let stamp_formatter = generate_time_code_b_terminated(&date);
+        let stamp = format!("{}", stamp_formatter);
+        let t_sep = stamp.find('T');
+        assert!(t_sep.is_some());
+        assert_eq!(t_sep.unwrap(), 8);
+        let z_terminator = stamp.find('Z');
+        assert!(z_terminator.is_some());
+        assert_eq!(
+            z_terminator.unwrap(),
+            FMT_STR_CODE_B_TERMINATED_WITH_SIZE.1 - 1
+        );
+        assert_eq!(stamp.len(), FMT_STR_CODE_B_TERMINATED_WITH_SIZE.1);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)]
+    fn test_ascii_timestamp_b_terminated_now() {
         let date = Utc::now();
         let stamp_formatter = generate_time_code_b_terminated(&date);
         let stamp = format!("{}", stamp_formatter);

src/time/cuc.rs

@@ -6,10 +6,9 @@
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
-use core::fmt::{Debug, Display, Formatter};
+use core::fmt::Debug;
 use core::ops::{Add, AddAssign};
 use core::time::Duration;
-use core::u64;
 
 use crate::ByteConversionError;
 
@@ -21,8 +20,6 @@ use super::{
     TimestampError, UnixTime,
 };
 #[cfg(feature = "std")]
-use std::error::Error;
-#[cfg(feature = "std")]
 use std::time::SystemTime;
 
 #[cfg(feature = "chrono")]
@@ -35,6 +32,7 @@ pub const P_FIELD_BASE: u8 = (CcsdsTimeCode::CucCcsdsEpoch as u8) << 4;
 /// Maximum length if the preamble field is not extended.
 pub const MAX_CUC_LEN_SMALL_PREAMBLE: usize = 8;
 
+/// Fractional resolution for the fractional part of the CUC time code.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -73,13 +71,14 @@ pub fn convert_fractional_part_to_ns(fractional_part: FractionalPart) -> u64 {
     10_u64.pow(9) * fractional_part.counter as u64 / div as u64
 }
 
+/// Convert the fractional resolution to the divisor used to calculate the fractional part.
 #[inline(always)]
 pub const fn fractional_res_to_div(res: FractionalResolution) -> u32 {
     // We do not use the full possible range for a given resolution. This is because if we did
     // that, the largest value would be equal to the counter being incremented by one. Thus, the
     // smallest allowed fractions value is 0 while the largest allowed fractions value is the
     // closest fractions value to the next counter increment.
-    2_u32.pow(8 * res as u32) - 1
+    (1u32 << (8 * res as u32)) - 1
 }
 
 /// Calculate the fractional part for a given resolution and subsecond nanoseconds.
@@ -104,63 +103,36 @@ pub fn fractional_part_from_subsec_ns(res: FractionalResolution, ns: u64) -> Fra
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+/// CUC error.
+#[derive(Copy, Clone, PartialEq, Eq, Debug, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum CucError {
+    /// Invalid CUC counter width.
+    #[error("invalid cuc counter byte width {0}")]
     InvalidCounterWidth(u8),
     /// Invalid counter supplied.
+    #[error("invalid cuc counter {counter} for width {width}")]
     InvalidCounter {
+        /// Width.
         width: u8,
+        /// Counter.
         counter: u64,
     },
+    /// Invalid fractions.
+    #[error("invalid cuc fractional part {value} for resolution {resolution:?}")]
     InvalidFractions {
+        /// Resolution.
         resolution: FractionalResolution,
+        /// Value.
         value: u64,
     },
+    /// Error while correcting for leap seconds.
+    #[error("error while correcting for leap seconds")]
     LeapSecondCorrectionError,
-    DateBeforeCcsdsEpoch(DateBeforeCcsdsEpochError),
-}
-
-impl Display for CucError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            CucError::InvalidCounterWidth(w) => {
-                write!(f, "invalid cuc counter byte width {w}")
-            }
-            CucError::InvalidCounter { width, counter } => {
-                write!(f, "invalid cuc counter {counter} for width {width}")
-            }
-            CucError::InvalidFractions { resolution, value } => {
-                write!(
-                    f,
-                    "invalid cuc fractional part {value} for resolution {resolution:?}"
-                )
-            }
-            CucError::LeapSecondCorrectionError => {
-                write!(f, "error while correcting for leap seconds")
-            }
-            CucError::DateBeforeCcsdsEpoch(e) => {
-                write!(f, "date before ccsds epoch: {e}")
-            }
-        }
-    }
-}
-
-#[cfg(feature = "std")]
-impl Error for CucError {
-    fn source(&self) -> Option<&(dyn Error + 'static)> {
-        match self {
-            CucError::DateBeforeCcsdsEpoch(e) => Some(e),
-            _ => None,
-        }
-    }
-}
-
-impl From<DateBeforeCcsdsEpochError> for CucError {
-    fn from(e: DateBeforeCcsdsEpochError) -> Self {
-        Self::DateBeforeCcsdsEpoch(e)
-    }
+    /// Data is before the CCSDS epoch.
+    #[error("date before ccsds epoch: {0}")]
+    DateBeforeCcsdsEpoch(#[from] DateBeforeCcsdsEpochError),
 }
 
 /// Tuple object where the first value is the width of the counter and the second value
@@ -169,14 +141,20 @@ impl From<DateBeforeCcsdsEpochError> for CucError {
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct WidthCounterPair(pub u8, pub u32);
 
+/// Fractional part of the CUC time code.
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct FractionalPart {
+    /// Resolution.
     pub resolution: FractionalResolution,
+    /// Counter.
     pub counter: u32,
 }
 
 impl FractionalPart {
+    /// Generic constructor.
+    ///
+    /// This function will panic if the counter is smaller than the calculated divisor.
     #[inline]
     pub const fn new(resolution: FractionalResolution, counter: u32) -> Self {
         let div = fractional_res_to_div(resolution);
@@ -199,6 +177,7 @@ impl FractionalPart {
         Self::new_with_seconds_resolution()
     }
 
+    /// Check constructor which verifies that the counter is larger than the divisor.
     #[inline]
     pub fn new_checked(resolution: FractionalResolution, counter: u32) -> Option<Self> {
         let div = fractional_res_to_div(resolution);
@@ -211,16 +190,19 @@ impl FractionalPart {
         })
     }
 
+    /// Fractional resolution.
     #[inline]
     pub fn resolution(&self) -> FractionalResolution {
         self.resolution
     }
 
+    /// Counter value.
     #[inline]
     pub fn counter(&self) -> u32 {
         self.counter
     }
 
+    /// Check whether the timestamp does not have a fractional part.
     #[inline]
     pub fn no_fractional_part(&self) -> bool {
         self.resolution == FractionalResolution::Seconds
@@ -287,17 +269,21 @@ pub struct CucTime {
 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct CucTimeWithLeapSecs {
+    /// CUC time.
     pub time: CucTime,
+    /// Leap seconds.
     pub leap_seconds: u32,
 }
 
 impl CucTimeWithLeapSecs {
+    /// Generic constructor.
     #[inline]
     pub fn new(time: CucTime, leap_seconds: u32) -> Self {
         Self { time, leap_seconds }
     }
 }
 
+/// p-field length.
 #[inline]
 pub fn pfield_len(pfield: u8) -> usize {
     if ((pfield >> 7) & 0b1) == 1 {
@@ -423,6 +409,7 @@ impl CucTime {
         Ok(())
     }
 
+    /// Creates a CUC timestamp from a Chrono DateTime object.
     #[cfg(feature = "chrono")]
     pub fn from_chrono_date_time(
         dt: &chrono::DateTime<chrono::Utc>,
@@ -490,21 +477,25 @@ impl CucTime {
         })
     }
 
+    /// CCSDS time code.
     #[inline]
     pub fn ccsds_time_code(&self) -> CcsdsTimeCode {
         CcsdsTimeCode::CucCcsdsEpoch
     }
 
+    /// Width and counter pair.
     #[inline]
     pub fn width_counter_pair(&self) -> WidthCounterPair {
         self.counter
     }
 
+    /// Counter width.
     #[inline]
     pub fn counter_width(&self) -> u8 {
         self.counter.0
     }
 
+    /// Counter value.
     #[inline]
     pub fn counter(&self) -> u32 {
         self.counter.1
@@ -516,11 +507,13 @@ impl CucTime {
         self.fractions
     }
 
+    /// Convert to the leap seconds helper.
     #[inline]
     pub fn to_leap_sec_helper(&self, leap_seconds: u32) -> CucTimeWithLeapSecs {
         CucTimeWithLeapSecs::new(*self, leap_seconds)
     }
 
+    /// Set the fractional part.
     #[inline]
     pub fn set_fractions(&mut self, fractions: FractionalPart) -> Result<(), CucError> {
         Self::verify_fractions_value(fractions)?;
@@ -567,16 +560,19 @@ impl CucTime {
         self.pfield |= self.fractions.resolution() as u8;
     }
 
+    /// Length of the counter from the p-field.
     #[inline]
     pub fn len_cntr_from_pfield(pfield: u8) -> u8 {
         ((pfield >> 2) & 0b11) + 1
     }
 
+    /// Length of the fractional part from the p-field.
     #[inline]
     pub fn len_fractions_from_pfield(pfield: u8) -> u8 {
         pfield & 0b11
     }
 
+    /// UNIX seconds.
     #[inline]
     pub fn unix_secs(&self, leap_seconds: u32) -> i64 {
         ccsds_epoch_to_unix_epoch(self.counter.1 as i64)
@@ -584,6 +580,7 @@ impl CucTime {
             .unwrap()
     }
 
+    /// Subsecond milliseconds part of the CUC time.
     #[inline]
     pub fn subsec_millis(&self) -> u16 {
         (self.subsec_nanos() / 1_000_000) as u16
@@ -606,6 +603,7 @@ impl CucTime {
         )
     }
 
+    /// Packed length from the raw p-field.
     #[inline]
     pub fn len_packed_from_pfield(pfield: u8) -> usize {
         let mut base_len: usize = 1;
@@ -947,6 +945,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_datetime_now() {
         let now = chrono::Utc::now();
         let cuc_now = CucTime::now(FractionalResolution::SixtyNs, LEAP_SECONDS);
@@ -1278,6 +1277,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn set_fract_resolution() {
         let mut stamp = CucTime::new(2000);
         stamp.set_fractional_resolution(FractionalResolution::SixtyNs);

src/time/mod.rs

@@ -3,10 +3,8 @@ use crate::ByteConversionError;
 #[cfg(feature = "chrono")]
 use chrono::{TimeZone, Utc};
 use core::cmp::Ordering;
-use core::fmt::{Display, Formatter};
 use core::ops::{Add, AddAssign, Sub};
 use core::time::Duration;
-use core::u8;
 
 #[allow(unused_imports)]
 #[cfg(not(feature = "std"))]
@@ -15,8 +13,6 @@ 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")]
@@ -26,19 +22,29 @@ pub mod ascii;
 pub mod cds;
 pub mod cuc;
 
+/// Conversion constant for converting CCSDS days to UNIX days.
 pub const DAYS_CCSDS_TO_UNIX: i32 = -4383;
+/// Seconds per day.
 pub const SECONDS_PER_DAY: u32 = 86400;
+/// Milliseconds per day.
 pub const MS_PER_DAY: u32 = SECONDS_PER_DAY * 1000;
+/// Nanoseconds per second.
 pub const NANOS_PER_SECOND: u32 = 1_000_000_000;
 
+/// CCSDS time code identifiers.
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum CcsdsTimeCode {
+    /// CUC with a CCSDS epoch (1958-01-01T00:00:00+00:00).
     CucCcsdsEpoch = 0b001,
+    /// CUC with a custom agency epoch.
     CucAgencyEpoch = 0b010,
+    /// CDS time code.
     Cds = 0b100,
+    /// CCS time code.
     Ccs = 0b101,
+    /// Agency defined time code.
     AgencyDefined = 0b110,
 }
 
@@ -64,96 +70,61 @@ pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCode, u8> {
     CcsdsTimeCode::try_from(raw_bits).map_err(|_| raw_bits)
 }
 
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+/// Date is before the CCSDS epoch.
+#[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[error("date before ccsds epoch: {0:?}")]
 pub struct DateBeforeCcsdsEpochError(UnixTime);
 
-impl Display for DateBeforeCcsdsEpochError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        write!(f, "date before ccsds epoch: {:?}", self.0)
-    }
-}
-
-#[cfg(feature = "std")]
-impl Error for DateBeforeCcsdsEpochError {}
-
-#[derive(Debug, PartialEq, Eq, Copy, Clone)]
+/// Generic timestamp error.
+#[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 #[non_exhaustive]
 pub enum TimestampError {
-    InvalidTimeCode { expected: CcsdsTimeCode, found: u8 },
-    ByteConversion(ByteConversionError),
-    Cds(cds::CdsError),
-    Cuc(cuc::CucError),
+    /// Invalid time code.
+    #[error("invalid time code, expected {expected:?}, found {found}")]
+    InvalidTimeCode {
+        /// Expected time code.
+        expected: CcsdsTimeCode,
+        /// Found raw time code.
+        found: u8,
+    },
+    /// Byte conversion error.
+    #[error("time stamp: byte conversion error: {0}")]
+    ByteConversion(#[from] ByteConversionError),
+    /// CDS timestamp error.
+    #[error("CDS error: {0}")]
+    Cds(#[from] cds::CdsError),
+    /// CUC timestamp error.
+    #[error("CUC error: {0}")]
+    Cuc(#[from] cuc::CucError),
+    /// Custom epoch is not supported.
+    #[error("custom epoch not supported")]
     CustomEpochNotSupported,
 }
 
-impl Display for TimestampError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            TimestampError::InvalidTimeCode { expected, found } => {
-                write!(
-                    f,
-                    "invalid raw time code value {found} for time code {expected:?}"
-                )
-            }
-            TimestampError::Cds(e) => {
-                write!(f, "cds error: {e}")
-            }
-            TimestampError::Cuc(e) => {
-                write!(f, "cuc error: {e}")
-            }
-            TimestampError::ByteConversion(e) => {
-                write!(f, "time stamp: {e}")
-            }
-            TimestampError::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)
-    }
-}
-
+/// [std] module.
 #[cfg(feature = "std")]
 pub mod std_mod {
     use crate::time::TimestampError;
     use std::time::SystemTimeError;
     use thiserror::Error;
 
+    /// [std] timestamp error.
     #[derive(Debug, Clone, Error)]
     pub enum StdTimestampError {
+        /// System time error.
         #[error("system time error: {0:?}")]
         SystemTime(#[from] SystemTimeError),
+        /// Generic timestamp error.
         #[error("timestamp error: {0}")]
         Timestamp(#[from] TimestampError),
     }
 }
 
+/// Seconds since epoch for the current system time.
 #[cfg(feature = "std")]
 pub fn seconds_since_epoch() -> f64 {
     SystemTime::now()
@@ -187,16 +158,19 @@ 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)
 }
 
+/// Convert CCSDS epoch to UNIX epoch.
 #[inline]
 pub const fn ccsds_epoch_to_unix_epoch(ccsds_epoch: i64) -> i64 {
     ccsds_epoch + (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)
 }
 
+/// Milliseconds of day for the current system time.
 #[cfg(feature = "std")]
 pub fn ms_of_day_using_sysclock() -> u32 {
     ms_of_day(seconds_since_epoch())
 }
 
+/// Milliseconds for the given 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
@@ -205,13 +179,16 @@ pub fn ms_of_day(seconds_since_epoch: f64) -> u32 {
     ms_of_day
 }
 
+/// Generic writable timestamp trait.
 pub trait TimeWriter {
+    /// Written length.
     fn len_written(&self) -> usize;
 
     /// Generic function to convert write a timestamp into a raw buffer.
     /// Returns the number of written bytes on success.
     fn write_to_bytes(&self, bytes: &mut [u8]) -> Result<usize, TimestampError>;
 
+    /// Convert to a owned [alloc::vec::Vec].
     #[cfg(feature = "alloc")]
     fn to_vec(&self) -> Result<alloc::vec::Vec<u8>, TimestampError> {
         let mut vec = alloc::vec![0; self.len_written()];
@@ -220,7 +197,9 @@ pub trait TimeWriter {
     }
 }
 
+/// Genmeric readable timestamp trait.
 pub trait TimeReader: Sized {
+    /// Create a timestamp from a raw byte buffer.
     fn from_bytes(buf: &[u8]) -> Result<Self, TimestampError>;
 }
 
@@ -230,6 +209,7 @@ pub trait TimeReader: Sized {
 /// practical because they are a very common and simple exchange format for time information.
 /// Therefore, it was decided to keep them in this trait as well.
 pub trait CcsdsTimeProvider {
+    /// Length when written to bytes.
     fn len_as_bytes(&self) -> usize;
 
     /// Returns the pfield of the time provider. The pfield can have one or two bytes depending
@@ -237,24 +217,37 @@ pub trait CcsdsTimeProvider {
     /// entry denotes the length of the pfield and the second entry is the value of the pfield
     /// in big endian format.
     fn p_field(&self) -> (usize, [u8; 2]);
+
+    /// CCSDS time code field.
     fn ccdsd_time_code(&self) -> CcsdsTimeCode;
 
-    fn unix_secs(&self) -> i64;
-    fn subsec_nanos(&self) -> u32;
+    /// UNIX time as seconds.
+    fn unix_secs(&self) -> i64 {
+        self.unix_time().secs
+    }
 
+    /// Subsecond nanoseconds.
+    fn subsec_nanos(&self) -> u32 {
+        self.unix_time().subsec_nanos
+    }
+
+    /// Subsecond milliseconds.
     fn subsec_millis(&self) -> u16 {
         (self.subsec_nanos() / 1_000_000) as u16
     }
 
+    /// UNIX time.
     fn unix_time(&self) -> UnixTime {
         UnixTime::new(self.unix_secs(), self.subsec_nanos())
     }
 
+    /// [chrono] date time.
     #[cfg(feature = "chrono")]
     fn chrono_date_time(&self) -> chrono::LocalResult<chrono::DateTime<chrono::Utc>> {
         chrono::Utc.timestamp_opt(self.unix_secs(), self.subsec_nanos())
     }
 
+    /// [time] library date] library date time.
     #[cfg(feature = "timelib")]
     fn timelib_date_time(&self) -> Result<time::OffsetDateTime, time::error::ComponentRange> {
         Ok(time::OffsetDateTime::from_unix_timestamp(self.unix_secs())?
@@ -336,6 +329,7 @@ impl UnixTime {
         }
     }
 
+    /// New UNIX time with only seconds, subseconds set to zero.
     pub fn new_only_secs(unix_seconds: i64) -> Self {
         Self {
             secs: unix_seconds,
@@ -343,15 +337,18 @@ impl UnixTime {
         }
     }
 
+    /// Sub-second milliseconds.
     #[inline]
     pub fn subsec_millis(&self) -> u16 {
         (self.subsec_nanos / 1_000_000) as u16
     }
 
+    /// Sub-second nanoseconds.
     pub fn subsec_nanos(&self) -> u32 {
         self.subsec_nanos
     }
 
+    /// Create a UNIX timestamp from the current system time.
     #[cfg(feature = "std")]
     pub fn now() -> Result<Self, SystemTimeError> {
         let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
@@ -359,27 +356,31 @@ impl UnixTime {
         Ok(Self::new(epoch as i64, now.subsec_nanos()))
     }
 
+    /// UNIX timestamp as a floating point number in seconds.
     #[inline]
     pub fn unix_secs_f64(&self) -> f64 {
         self.secs as f64 + (self.subsec_nanos as f64 / 1_000_000_000.0)
     }
 
+    /// UNIX timestamp as seconds, discards the sub-second part.
     pub fn as_secs(&self) -> i64 {
         self.secs
     }
 
+    /// UNIX timestamp as [chrono] date time.
     #[cfg(feature = "chrono")]
     pub fn chrono_date_time(&self) -> chrono::LocalResult<chrono::DateTime<chrono::Utc>> {
         Utc.timestamp_opt(self.secs, self.subsec_nanos)
     }
 
+    /// UNIX timestamp as [time] library date time.
     #[cfg(feature = "timelib")]
     pub fn timelib_date_time(&self) -> Result<time::OffsetDateTime, time::error::ComponentRange> {
         Ok(time::OffsetDateTime::from_unix_timestamp(self.as_secs())?
             + time::Duration::nanoseconds(self.subsec_nanos().into()))
     }
 
-    // Calculate the difference in milliseconds between two UnixTimestamps
+    /// Calculate the difference in milliseconds between two UnixTimestamps
     pub fn diff_in_millis(&self, other: &UnixTime) -> Option<i64> {
         let seconds_difference = self.secs.checked_sub(other.secs)?;
         // Convert seconds difference to milliseconds
@@ -449,7 +450,9 @@ impl Ord for UnixTime {
 /// so the sign information is supplied separately.
 #[derive(Clone, Copy, PartialEq, Eq)]
 pub struct StampDiff {
+    /// Positive duration flag.
     pub positive_duration: bool,
+    /// Absolute duration.
     pub duration_absolute: Duration,
 }
 
@@ -551,6 +554,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_get_current_time() {
         let sec_floats = seconds_since_epoch();
         assert!(sec_floats > 0.0);
@@ -565,6 +569,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_ccsds_epoch() {
         let now = SystemTime::now()
             .duration_since(SystemTime::UNIX_EPOCH)
@@ -685,6 +690,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg_attr(miri, ignore)]
     fn test_from_now() {
         let stamp_now = UnixTime::now().unwrap();
         let dt_now = stamp_now.chrono_date_time().unwrap();
@@ -741,7 +747,7 @@ mod tests {
     fn test_cuc_error_printout() {
         let cuc_error = CucError::InvalidCounterWidth(12);
         let stamp_error = TimestampError::from(cuc_error);
-        assert_eq!(stamp_error.to_string(), format!("cuc error: {cuc_error}"));
+        assert_eq!(stamp_error.to_string(), format!("CUC error: {cuc_error}"));
     }
 
     #[test]

src/util.rs

@@ -1,14 +1,16 @@
+//! # Utility module.
 use crate::ByteConversionError;
-use core::fmt::{Debug, Display, Formatter};
+use core::fmt::Debug;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-#[cfg(feature = "std")]
-use std::error::Error;
 
+/// Helper traits for types which can be converted to a byte array.
 pub trait ToBeBytes {
+    /// Concrete byte array type.
     type ByteArray: AsRef<[u8]>;
     /// Length when written to big endian bytes.
     fn written_len(&self) -> usize;
+    /// Convert to big endian byte array.
     fn to_be_bytes(&self) -> Self::ByteArray;
 }
 
@@ -82,14 +84,17 @@ impl ToBeBytes for u64 {
     }
 }
 
+/// Helper trait for unsigned enumerations.
 pub trait UnsignedEnum {
     /// Size of the unsigned enumeration in bytes.
     fn size(&self) -> usize;
     /// Write the unsigned enumeration to a raw buffer. Returns the written size on success.
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
 
-    fn value(&self) -> u64;
+    /// Type-erased raw value.
+    fn value_raw(&self) -> u64;
 
+    /// Convert to a [alloc::vec::Vec].
     #[cfg(feature = "alloc")]
     fn to_vec(&self) -> alloc::vec::Vec<u8> {
         let mut buf = alloc::vec![0; self.size()];
@@ -98,51 +103,36 @@ pub trait UnsignedEnum {
     }
 }
 
+/// Extension trait for unsigned enumerations.
 pub trait UnsignedEnumExt: UnsignedEnum + Debug + Copy + Clone + PartialEq + Eq {}
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+/// Unsigned byte field errors.
+#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum UnsignedByteFieldError {
     /// Value is too large for specified width of byte field.
+    #[error("value {value} too large for width {width}")]
     ValueTooLargeForWidth {
+        /// Width in bytes.
         width: usize,
+        /// Value.
         value: u64,
     },
     /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
     /// applicable, for example for conversions.
+    #[error("invalid width {found}, expected {expected:?}")]
     InvalidWidth {
+        /// Found width.
         found: usize,
+        /// Expected width.
         expected: Option<usize>,
     },
-    ByteConversionError(ByteConversionError),
+    /// Error during byte conversion.
+    #[error("byte conversion error: {0}")]
+    ByteConversionError(#[from] ByteConversionError),
 }
 
-impl From<ByteConversionError> for UnsignedByteFieldError {
-    #[inline]
-    fn from(value: ByteConversionError) -> Self {
-        Self::ByteConversionError(value)
-    }
-}
-
-impl Display for UnsignedByteFieldError {
-    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
-        match self {
-            Self::ByteConversionError(e) => {
-                write!(f, "low level byte conversion error: {e}")
-            }
-            Self::InvalidWidth { found, .. } => {
-                write!(f, "invalid width {found}, only 1, 2, 4 and 8 are allowed.")
-            }
-            Self::ValueTooLargeForWidth { width, value } => {
-                write!(f, "value {value} too large for width {width}")
-            }
-        }
-    }
-}
-
-#[cfg(feature = "std")]
-impl Error for UnsignedByteFieldError {}
-
 /// Type erased variant.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@@ -153,16 +143,19 @@ pub struct UnsignedByteField {
 }
 
 impl UnsignedByteField {
+    /// Generic constructor.
     #[inline]
     pub const fn new(width: usize, value: u64) -> Self {
         Self { width, value }
     }
 
+    /// Type-erased raw value.
     #[inline]
-    pub const fn value_const(&self) -> u64 {
+    pub const fn value(&self) -> u64 {
         self.value
     }
 
+    /// Construct from raw bytes, assuming big-endian byte order.
     #[inline]
     pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, UnsignedByteFieldError> {
         if width > buf.len() {
@@ -202,8 +195,8 @@ impl UnsignedEnum for UnsignedByteField {
     }
 
     #[inline]
-    fn value(&self) -> u64 {
-        self.value_const()
+    fn value_raw(&self) -> u64 {
+        self.value()
     }
 
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
@@ -239,6 +232,7 @@ impl UnsignedEnum for UnsignedByteField {
     }
 }
 
+/// Generic type erased unsigned byte field.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -247,11 +241,13 @@ pub struct GenericUnsignedByteField<TYPE: Copy + Into<u64>> {
 }
 
 impl<TYPE: Copy + Into<u64>> GenericUnsignedByteField<TYPE> {
+    /// Generic constructor.
     pub const fn new(val: TYPE) -> Self {
         Self { value: val }
     }
 
-    pub const fn value_typed(&self) -> TYPE {
+    /// Raw value.
+    pub const fn value(&self) -> TYPE {
         self.value
     }
 }
@@ -274,20 +270,29 @@ impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericUnsignedByteFie
     }
 
     #[inline]
-    fn value(&self) -> u64 {
-        self.value_typed().into()
+    fn value_raw(&self) -> u64 {
+        self.value().into()
     }
 }
 
+/// Alias for [GenericUnsignedByteField] with [()] generic.
 pub type UnsignedByteFieldEmpty = GenericUnsignedByteField<()>;
+/// Alias for [GenericUnsignedByteField] with [u8] generic.
 pub type UnsignedByteFieldU8 = GenericUnsignedByteField<u8>;
+/// Alias for [GenericUnsignedByteField] with [u16] generic.
 pub type UnsignedByteFieldU16 = GenericUnsignedByteField<u16>;
+/// Alias for [GenericUnsignedByteField] with [u32] generic.
 pub type UnsignedByteFieldU32 = GenericUnsignedByteField<u32>;
+/// Alias for [GenericUnsignedByteField] with [u64] generic.
 pub type UnsignedByteFieldU64 = GenericUnsignedByteField<u64>;
 
+/// Alias for [UnsignedByteFieldU8]
 pub type UbfU8 = UnsignedByteFieldU8;
+/// Alias for [UnsignedByteFieldU16]
 pub type UbfU16 = UnsignedByteFieldU16;
+/// Alias for [UnsignedByteFieldU32]
 pub type UbfU32 = UnsignedByteFieldU32;
+/// Alias for [UnsignedByteFieldU64]
 pub type UbfU64 = UnsignedByteFieldU64;
 
 impl From<UnsignedByteFieldU8> for UnsignedByteField {
@@ -378,7 +383,7 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU64 {
 }
 
 #[cfg(test)]
-pub mod tests {
+mod tests {
     use crate::util::{
         UnsignedByteField, UnsignedByteFieldError, UnsignedByteFieldU16, UnsignedByteFieldU32,
         UnsignedByteFieldU64, UnsignedByteFieldU8, UnsignedEnum,
@@ -399,7 +404,7 @@ pub mod tests {
         for val in buf.iter().skip(1) {
             assert_eq!(*val, 0);
         }
-        assert_eq!(u8.value_typed(), 5);
+        assert_eq!(u8.value_raw(), 5);
         assert_eq!(u8.value(), 5);
     }
 
@@ -417,7 +422,7 @@ pub mod tests {
         for val in buf.iter().skip(2) {
             assert_eq!(*val, 0);
         }
-        assert_eq!(u16.value_typed(), 3823);
+        assert_eq!(u16.value_raw(), 3823);
         assert_eq!(u16.value(), 3823);
     }
 
@@ -435,7 +440,7 @@ pub mod tests {
         (4..8).for_each(|i| {
             assert_eq!(buf[i], 0);
         });
-        assert_eq!(u32.value_typed(), 80932);
+        assert_eq!(u32.value_raw(), 80932);
         assert_eq!(u32.value(), 80932);
     }
 
@@ -450,7 +455,7 @@ pub mod tests {
         assert_eq!(len, 8);
         let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
         assert_eq!(raw_val, 5999999);
-        assert_eq!(u64.value_typed(), 5999999);
+        assert_eq!(u64.value_raw(), 5999999);
         assert_eq!(u64.value(), 5999999);
     }