Merge pull request 'add length check for CCSDS reader' (#213) from add-len-check-ccsds-reader into main

Reviewed-on: #213

.github/workflows/ci.yml

@@ -39,12 +39,13 @@ jobs:
       matrix:
         target:
           - armv7-unknown-linux-gnueabihf
+          - thumbv6m-none-eabi
           - thumbv7em-none-eabihf
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable
         with:
-          targets: "armv7-unknown-linux-gnueabihf, thumbv7em-none-eabihf"
+          targets: "armv7-unknown-linux-gnueabihf, thumbv7em-none-eabihf, thumbv6m-none-eabi"
       - run: cargo check --release --target=${{matrix.target}} --no-default-features
 
   fmt:
@@ -63,7 +64,7 @@ jobs:
     steps:
       - 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
+      - run: RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options" cargo +nightly doc --all-features --no-deps
 
   clippy:
     name: Clippy

.gitignore

@@ -1,6 +1,5 @@
 # Rust
 /target
-/Cargo.lock
 
 # CLion
 /.idea/*

CHANGELOG.md

@@ -8,6 +8,58 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.18.0] ?
+
+## Changed
+
+- Added distinction between `CcsdsPacketReader::user_data` and `CcsdsPacketReader::packet_data`.
+- Added distinction between `CcsdsPacketCreatorWithReservedData::user_data` and
+  `CcsdsPacketCreatorWithReservedData::packet_data`, including mutable variants as well.
+- `SequenceCounter::MAX_BIT_WIDTH` is now a regular trait method `SequenceCounter::max_bit_width`
+  to allow dyn compatibility and easier usage in trait objects.
+- Improved type level support in USLP module by using VC ID type `u6` and MAP ID type `u4`.
+
+## Added
+
+- `checksum` getter for `CcsdsPacketReader`.
+- Added `SequenceCounterOnFile` which persists the sequence counter by writing it to a file.
+- Added `SequenceCounter::set` method which allows manually setting an initial value.
+- Added `CcsdsPacketReader::raw_data` full data getter.
+- `UslpFrameCreator` constructor
+- Additional reader methods on `UslpFrameReader`
+
+## Removed
+
+- `SequenceCounter::increment_mut` and `SequenceCounter::get_and_increment_mut`
+
+# [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
@@ -650,7 +702,8 @@ The timestamp of `PusTm` is now optional. See Added and Changed section for deta
 Initial release with CCSDS Space Packet Primary Header implementation and basic PUS TC and TM
 implementations.
 
-[unreleased]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.16.1...HEAD
+[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

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+ "windows-link",
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+
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+name = "zerocopy"
+version = "0.8.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0894878a5fa3edfd6da3f88c4805f4c8558e2b996227a3d864f47fe11e38282c"
+dependencies = [
+ "zerocopy-derive",
+]
+
+[[package]]
+name = "zerocopy-derive"
+version = "0.8.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "88d2b8d9c68ad2b9e4340d7832716a4d21a22a1154777ad56ea55c51a9cf3831"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "spacepackets"
-version = "0.16.1"
+version = "0.17.0"
 edition = "2021"
 rust-version = "1.83"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]
@@ -14,16 +14,16 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 
 [dependencies]
 crc = "3"
-delegate = ">=0.8, <=0.13"
+delegate = "0.13"
 paste = "1"
 zerocopy = { version = "0.8", features = ["derive"] }
 thiserror = { version = "2", default-features = false }
-num_enum = { version = ">0.5, <=0.7", default-features = false }
+num_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 = "1"
+portable-atomic = { version = "1", optional = true }
-bitbybit = "1.4"
+bitbybit = "2"
 
 time = { version = "0.3", default-features = false, optional = true }
 chrono = { version = "0.4", default-features = false, optional = true }
@@ -32,6 +32,7 @@ defmt = { version = "1", default-features = false, optional = true }
 [features]
 default = ["std"]
 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"]
@@ -40,6 +41,7 @@ timelib = ["dep:time"]
 [dev-dependencies]
 postcard = { version = "1", features = ["alloc"] }
 chrono = "0.4"
+tempfile = "3"
 
 [package.metadata.docs.rs]
 all-features = true

README.md

@@ -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
 

justfile

@@ -1,9 +1,12 @@
-all: check build embedded test clippy fmt docs coverage
+all: check build clippy embedded test check-fmt docs coverage
 
 clippy:
   cargo clippy -- -D warnings
 
 fmt:
+  cargo fmt --all
+
+check-fmt:
   cargo fmt --all -- --check
 
 check:
@@ -11,6 +14,7 @@ check:
 
 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
@@ -20,12 +24,10 @@ build:
   cargo build --all-features
 
 docs:
-  export RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options"
+  RUSTDOCFLAGS="--cfg docsrs -Z unstable-options --generate-link-to-definition" cargo +nightly doc --all-features --no-deps
-  cargo +nightly doc --all-features
 
 docs-html:
-  export RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options"
+  RUSTDOCFLAGS="--cfg docsrs -Z unstable-options --generate-link-to-definition" cargo +nightly doc --all-features --open
-  cargo +nightly doc --all-features --open
 
 coverage:
   cargo llvm-cov nextest

src/cfdp/lv.rs

@@ -8,6 +8,7 @@ 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.
@@ -63,8 +64,10 @@ 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<'_>, TlvLvDataTooLargeError> {
         if data.len() > u8::MAX as usize {
@@ -118,6 +121,7 @@ impl<'data> Lv<'data> {
         self.data.len() == 0
     }
 
+    /// Raw value part of the LV.
     #[inline]
     pub fn value(&self) -> &[u8] {
         self.data
@@ -179,7 +183,7 @@ impl<'data> Lv<'data> {
 }
 
 #[cfg(test)]
-pub mod tests {
+mod tests {
     use alloc::string::ToString;
 
     use super::*;

src/cfdp/mod.rs

@@ -13,43 +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;
 
+/// 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,
 }
 
+/// 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,
 }
 
+/// 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,
 }
 
+/// 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,
 }
 
@@ -78,7 +90,9 @@ impl From<CrcFlag> for bool {
 #[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum SegmentMetadataFlag {
+    /// Segment metadata not present.
     NotPresent = 0,
+    /// Segment metadata present.
     Present = 1,
 }
 
@@ -89,22 +103,30 @@ pub enum SegmentMetadataFlag {
 #[bitbybit::bitenum(u1, exhaustive = true)]
 #[repr(u8)]
 pub enum SegmentationControl {
+    /// No record boundary preservation.
     NoRecordBoundaryPreservation = 0,
+    /// With record boundary preservation.
     WithRecordBoundaryPreservation = 1,
 }
 
+/// 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,
 }
 
+/// CFDP condition codes.
 #[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -113,15 +135,25 @@ pub enum FaultHandlerCode {
 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,
+    /// 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,
@@ -129,6 +161,7 @@ pub enum ConditionCode {
     CancelRequestReceived = 0b1111,
 }
 
+/// Large file flag.
 #[derive(Debug, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -151,6 +184,7 @@ 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,
@@ -161,28 +195,28 @@ 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 {
+/// Raw null checksum.
-    fn default() -> Self {
-        Self::NullChecksum
-    }
-}
-
 pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
 
+/// 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))]
@@ -199,16 +233,21 @@ pub struct InvalidTlvTypeFieldError {
     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 {
+    /// 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

src/cfdp/pdu/ack.rs

@@ -1,3 +1,4 @@
+//! # Acknowledgement (ACK) PDU packet implementation.
 use crate::{
     cfdp::{ConditionCode, CrcFlag, Direction, TransactionStatus},
     ByteConversionError,
@@ -10,6 +11,7 @@ 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);
@@ -28,15 +30,16 @@ 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, InvalidAckedDirectiveCodeError> {
-        if directive_code_of_acked_pdu == FileDirectiveType::EofPdu {
+        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(InvalidAckedDirectiveCodeError(directive_code_of_acked_pdu));
@@ -52,6 +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,
@@ -60,13 +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,
@@ -75,28 +84,32 @@ 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
@@ -110,6 +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)?;
@@ -117,13 +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;
@@ -134,8 +148,8 @@ impl AckPdu {
                     expected: None,
                 }
             })?;
-        if acked_directive_type != FileDirectiveType::EofPdu
+        if acked_directive_type != FileDirectiveType::Eof
-            && acked_directive_type != FileDirectiveType::FinishedPdu
+            && acked_directive_type != FileDirectiveType::Finished
         {
             return Err(PduError::InvalidDirectiveType {
                 found: acked_directive_type as u8,
@@ -167,11 +181,11 @@ impl 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;
@@ -185,6 +199,7 @@ impl AckPdu {
         Ok(current_idx)
     }
 
+    /// Length of the written PDU in bytes.
     pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
@@ -198,7 +213,7 @@ impl CfdpPdu for AckPdu {
 
     #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::AckPdu)
+        Some(FileDirectiveType::Ack)
     }
 }
 
@@ -230,10 +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!(
+        assert_eq!(ack_pdu.file_directive_type(), Some(FileDirectiveType::Ack));
-            ack_pdu.file_directive_type(),
-            Some(FileDirectiveType::AckPdu)
-        );
         assert_eq!(ack_pdu.transmission_mode(), TransmissionMode::Acknowledged);
         assert_eq!(ack_pdu.direction(), expected_dir);
         assert_eq!(ack_pdu.source_id(), TEST_SRC_ID.into());
@@ -247,14 +259,14 @@ mod tests {
         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);
     }
@@ -273,8 +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[7], FileDirectiveType::Ack as u8);
-        assert_eq!((buf[8] >> 4) & 0b1111, FileDirectiveType::FinishedPdu 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);
@@ -292,7 +304,7 @@ mod tests {
         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,
         )
@@ -320,12 +332,12 @@ mod tests {
         assert_eq!(
             AckPdu::new(
                 pdu_header,
-                FileDirectiveType::MetadataPdu,
+                FileDirectiveType::Metadata,
                 ConditionCode::NoError,
                 TransactionStatus::Active,
             )
             .unwrap_err(),
-            InvalidAckedDirectiveCodeError(FileDirectiveType::MetadataPdu)
+            InvalidAckedDirectiveCodeError(FileDirectiveType::Metadata)
         );
     }
 
@@ -372,7 +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);
     }

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,
@@ -25,6 +26,7 @@ pub struct EofPdu {
 }
 
 impl EofPdu {
+    /// Constructor.
     pub fn new(
         mut pdu_header: PduHeader,
         condition_code: ConditionCode,
@@ -45,6 +47,7 @@ impl EofPdu {
         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,
@@ -55,21 +58,25 @@ impl EofPdu {
         )
     }
 
+    /// 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
@@ -90,6 +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)?;
@@ -102,13 +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;
@@ -145,7 +153,7 @@ impl 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;
@@ -165,6 +173,7 @@ impl EofPdu {
         Ok(current_idx)
     }
 
+    /// Length of the written PDU in bytes.
     pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
@@ -178,7 +187,7 @@ impl CfdpPdu for EofPdu {
 
     #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::EofPdu)
+        Some(FileDirectiveType::Eof)
     }
 }
 
@@ -221,10 +230,7 @@ mod tests {
         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!(
+        assert_eq!(eof_pdu.file_directive_type(), Some(FileDirectiveType::Eof));
-            eof_pdu.file_directive_type(),
-            Some(FileDirectiveType::EofPdu)
-        );
         assert_eq!(eof_pdu.transmission_mode(), TransmissionMode::Acknowledged);
         assert_eq!(eof_pdu.direction(), Direction::TowardsReceiver);
         assert_eq!(eof_pdu.source_id(), TEST_SRC_ID.into());
@@ -253,7 +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,

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,
@@ -10,18 +11,24 @@ use serde::{Deserialize, Serialize};
 
 use super::{CfdpPdu, FileDirectiveType, WritablePduPacket};
 
+/// 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> {
@@ -30,6 +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]>,
@@ -45,16 +53,19 @@ 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
     }
 
+    /// Length of the written segment metadata structure.
     #[inline]
     pub fn len_written(&self) -> usize {
         // Map empty metadata to 0 and slice to its length.
@@ -124,8 +135,8 @@ impl FdPduBase<'_> {
         if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
             len += 4;
         }
-        if self.segment_metadata.is_some() {
+        if let Some(segment_metadata) = self.segment_metadata {
-            len += self.segment_metadata.as_ref().unwrap().len_written()
+            len += segment_metadata.len_written()
         }
         len += file_data_len as usize;
         if self.crc_flag() == CrcFlag::WithCrc {
@@ -136,12 +147,8 @@ impl FdPduBase<'_> {
 
     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() {
+        if let Some(segment_metadata) = self.segment_metadata {
-            current_idx += self
+            current_idx += segment_metadata.write_to_bytes(&mut buf[current_idx..])?;
-                .segment_metadata
-                .as_ref()
-                .unwrap()
-                .write_to_bytes(&mut buf[current_idx..])?;
         }
         current_idx += write_fss_field(
             self.pdu_header.common_pdu_conf().file_flag,
@@ -169,24 +176,27 @@ pub struct FileDataPdu<'seg_meta, 'file_data> {
 }
 
 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_generic(pdu_header, Some(segment_metadata), offset, file_data)
+        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_generic(pdu_header, None, offset, file_data)
+        Self::new(pdu_header, None, offset, file_data)
     }
 
-    pub fn new_generic(
+    /// Generic constructor for a file data PDU.
+    pub fn new(
         mut pdu_header: PduHeader,
         segment_metadata: Option<SegmentMetadata<'seg_meta>>,
         offset: u64,
@@ -213,26 +223,31 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
             .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)?;
@@ -281,6 +296,7 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
         Ok(current_idx)
     }
 
+    /// Length of the written PDU.
     pub fn len_written(&self) -> usize {
         self.common.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
@@ -323,20 +339,23 @@ pub struct FileDataPduCreatorWithReservedDatafield<'seg_meta> {
 }
 
 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_generic(pdu_header, Some(segment_metadata), offset, file_data_len)
+        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_generic(pdu_header, None, offset, file_data_len)
+        Self::new(pdu_header, None, offset, file_data_len)
     }
 
-    pub fn new_generic(
+    /// Generic constructor.
+    pub fn new(
         mut pdu_header: PduHeader,
         segment_metadata: Option<SegmentMetadata<'seg_meta>>,
         offset: u64,
@@ -362,6 +381,7 @@ impl<'seg_meta> FileDataPduCreatorWithReservedDatafield<'seg_meta> {
         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()
     }
@@ -423,6 +443,7 @@ pub struct FileDataPduCreatorWithUnwrittenData<'buf> {
 }
 
 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]

src/cfdp/pdu/finished.rs

@@ -1,3 +1,4 @@
+//! # Finished PDU packet implementation.
 use crate::cfdp::pdu::{
     add_pdu_crc, generic_length_checks_pdu_deserialization, FileDirectiveType, PduError, PduHeader,
 };
@@ -13,23 +14,31 @@ use serde::{Deserialize, Serialize};
 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,
 }
 
@@ -65,6 +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,
@@ -82,6 +92,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         )
     }
 
+    /// Generic constructor.
     pub fn new(
         mut pdu_header: PduHeader,
         condition_code: ConditionCode,
@@ -109,32 +120,37 @@ 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
@@ -166,7 +182,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         }
 
         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)
@@ -184,6 +200,7 @@ impl<'fs_responses> FinishedPduCreator<'fs_responses> {
         Ok(current_idx)
     }
 
+    /// Length of the written PDU in bytes.
     pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
@@ -197,7 +214,7 @@ impl CfdpPdu for FinishedPduCreator<'_> {
 
     #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::FinishedPdu)
+        Some(FileDirectiveType::Finished)
     }
 }
 
@@ -242,6 +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))]
@@ -269,13 +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;
@@ -297,11 +315,13 @@ 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 {
@@ -310,26 +330,31 @@ 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
@@ -399,7 +424,7 @@ impl CfdpPdu for FinishedPduReader<'_> {
 
     #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::FinishedPdu)
+        Some(FileDirectiveType::Finished)
     }
 }
 
@@ -468,7 +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(),
@@ -500,7 +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,
@@ -626,7 +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()

src/cfdp/pdu/metadata.rs

@@ -1,3 +1,4 @@
+//! # Metadata PDU packet implementation.
 #[cfg(feature = "alloc")]
 use super::tlv::TlvOwned;
 use crate::cfdp::lv::Lv;
@@ -16,16 +17,21 @@ 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,
@@ -35,6 +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],
@@ -46,6 +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],
@@ -54,6 +62,7 @@ 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();
@@ -77,6 +86,7 @@ pub struct MetadataPduCreator<'src_name, 'dest_name, 'opts> {
 }
 
 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,
@@ -92,6 +102,7 @@ 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,
@@ -108,6 +119,7 @@ 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,
@@ -128,26 +140,31 @@ 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
     }
 
+    /// PDU header.
     #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
     }
 
+    /// Raw options.
     #[inline]
     pub fn options(&self) -> &'opts [u8] {
         self.options
@@ -191,7 +208,7 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         }
 
         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);
@@ -215,6 +232,7 @@ impl<'src_name, 'dest_name, 'opts> MetadataPduCreator<'src_name, 'dest_name, 'op
         Ok(current_idx)
     }
 
+    /// Length of the written PDU in bytes.
     pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
@@ -228,7 +246,7 @@ impl CfdpPdu for MetadataPduCreator<'_, '_, '_> {
 
     #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::MetadataPdu)
+        Some(FileDirectiveType::Metadata)
     }
 }
 
@@ -291,10 +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)?;
@@ -308,13 +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;
@@ -350,26 +370,31 @@ 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
     }
 
+    /// Source file name as a [Lv].
     #[inline]
     pub fn src_file_name(&self) -> Lv<'_> {
         self.src_file_name
     }
 
+    /// Destination file name as a [Lv].
     #[inline]
     pub fn dest_file_name(&self) -> Lv<'_> {
         self.dest_file_name
@@ -383,12 +408,12 @@ impl CfdpPdu for MetadataPduReader<'_> {
     }
 
     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;
@@ -471,7 +496,7 @@ pub mod tests {
         );
         assert_eq!(
             metadata_pdu.file_directive_type(),
-            Some(FileDirectiveType::MetadataPdu)
+            Some(FileDirectiveType::Metadata)
         );
         assert_eq!(
             metadata_pdu.transmission_mode(),
@@ -502,7 +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);
@@ -807,10 +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, found 255, expected Some(MetadataPdu)"
+                "invalid directive type, found 255, expected Some(Metadata)"
             );
         } else {
             panic!("Expected InvalidDirectiveType error, got {:?}", error);
@@ -827,16 +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!(found, FileDirectiveType::Eof);
-            assert_eq!(expected, FileDirectiveType::MetadataPdu);
+            assert_eq!(expected, FileDirectiveType::Metadata);
             assert_eq!(
                 error.to_string(),
-                "wrong directive type, found EofPdu, expected MetadataPdu"
+                "wrong directive type, found Eof, expected Metadata"
             );
         } else {
             panic!("Expected InvalidDirectiveType error, got {:?}", error);

src/cfdp/pdu/mod.rs

@@ -15,24 +15,34 @@ 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,
+    /// EOF.
-    FinishedPdu = 0x05,
+    Eof = 0x04,
-    AckPdu = 0x06,
+    /// Finished.
-    MetadataPdu = 0x07,
+    Finished = 0x05,
-    NakPdu = 0x08,
+    /// ACK.
-    PromptPdu = 0x09,
+    Ack = 0x06,
-    KeepAlivePdu = 0x0c,
+    /// Metadata.
+    Metadata = 0x07,
+    /// NAK.
+    Nak = 0x08,
+    /// Prompt.
+    Prompt = 0x09,
+    /// Keep Alive.
+    KeepAlive = 0x0c,
 }
 
+/// 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 {
+    /// Byte conversion error.
     #[error("byte conversion error: {0}")]
     ByteConversion(#[from] ByteConversionError),
     /// Found version ID invalid, not equal to [super::CFDP_VERSION_2].
@@ -44,27 +54,35 @@ pub enum PduError {
     /// 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 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>,
     },
+    /// 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.
@@ -74,6 +92,7 @@ pub enum PduError {
     /// [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.
@@ -96,9 +115,15 @@ impl From<InvalidAckedDirectiveCodeError> for PduError {
     }
 }
 
+/// 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
@@ -112,48 +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>;
 }
 
@@ -169,15 +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>,
@@ -210,6 +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>,
@@ -227,6 +269,7 @@ impl CommonPduConfig {
         )
     }
 
+    /// Source ID (file sender).
     #[inline]
     pub fn source_id(&self) -> UnsignedByteField {
         self.source_entity_id
@@ -255,6 +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,
@@ -267,6 +311,7 @@ impl CommonPduConfig {
         Ok(())
     }
 
+    /// Destination ID (file receiver).
     #[inline]
     pub fn dest_id(&self) -> UnsignedByteField {
         self.dest_entity_id
@@ -305,6 +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.
@@ -322,8 +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,
@@ -340,6 +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(
@@ -351,6 +400,7 @@ impl PduHeader {
         )
     }
 
+    /// Constructor for a file directive PDU.
     #[inline]
     pub fn new_for_file_directive(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
         Self::new_generic(
@@ -362,6 +412,7 @@ 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(
@@ -373,6 +424,7 @@ impl PduHeader {
         )
     }
 
+    /// Generic constructor.
     #[inline]
     pub fn new_generic(
         pdu_type: PduType,
@@ -399,6 +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()
@@ -411,6 +464,7 @@ impl PduHeader {
         self.header_len() + self.pdu_datafield_len as usize
     }
 
+    /// 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.
@@ -578,21 +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

src/cfdp/pdu/nak.rs

@@ -1,3 +1,4 @@
+//! # NAK PDU packet implementation.
 use crate::{
     cfdp::{CrcFlag, Direction, LargeFileFlag},
     ByteConversionError,
@@ -8,6 +9,7 @@ use super::{
     PduHeader, WritablePduPacket,
 };
 
+/// Invalid start or end of scope value.
 #[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
 #[error("invalid start or end of scope value for NAK PDU")]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -52,6 +54,7 @@ fn write_start_and_end_of_scope(
     current_index
 }
 
+/// Buffer is too small to even hold a PDU header.
 #[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
 #[error("packet buffer too small for PDU header")]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -94,11 +97,14 @@ pub fn calculate_max_segment_requests(
 #[derive(Debug, PartialEq, Eq, Clone)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum SegmentRequests<'a> {
+    /// Segment requests for normal file sizes bounded by [u32::MAX].
     U32Pairs(&'a [(u32, u32)]),
+    /// Segment requests for large file sizes bounded by [u64::MAX].
     U64Pairs(&'a [(u64, u64)]),
 }
 
 impl SegmentRequests<'_> {
+    /// Wrapped segment requests are empty.
     #[inline]
     pub fn is_empty(&self) -> bool {
         match self {
@@ -152,6 +158,7 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
         )
     }
 
+    /// Constructor for large file sizes.
     pub fn new_large_file_size(
         pdu_header: PduHeader,
         start_of_scope: u64,
@@ -206,21 +213,25 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
         Ok(nak_pdu)
     }
 
+    /// Start of scope of the NAK PDU.
     #[inline]
     pub fn start_of_scope(&self) -> u64 {
         self.start_of_scope
     }
 
+    /// End of scope of the NAK PDU.
     #[inline]
     pub fn end_of_scope(&self) -> u64 {
         self.end_of_scope
     }
 
+    /// Semgent requests.
     #[inline]
     pub fn segment_requests(&self) -> Option<&SegmentRequests<'_>> {
         self.segment_requests.as_ref()
     }
 
+    /// Number of segment requests.
     #[inline]
     pub fn num_segment_reqs(&self) -> usize {
         match &self.segment_requests {
@@ -232,6 +243,7 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
         }
     }
 
+    /// PDU header.
     #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
@@ -252,7 +264,7 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
             .into());
         }
         let mut current_index = self.pdu_header.write_to_bytes(buf)?;
-        buf[current_index] = FileDirectiveType::NakPdu as u8;
+        buf[current_index] = FileDirectiveType::Nak as u8;
         current_index += 1;
 
         current_index = write_start_and_end_of_scope(
@@ -309,7 +321,7 @@ impl CfdpPdu for NakPduCreator<'_> {
 
     #[inline]
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::NakPdu)
+        Some(FileDirectiveType::Nak)
     }
 }
 
@@ -337,6 +349,8 @@ pub struct NakPduCreatorWithReservedSeqReqsBuf<'buf> {
 }
 
 impl<'buf> NakPduCreatorWithReservedSeqReqsBuf<'buf> {
+    /// Calculartes the maximum amount of segment requests which fit into a packet with the
+    /// provided parameters.
     pub fn calculate_max_segment_requests(
         max_packet_size: usize,
         pdu_header: &PduHeader,
@@ -344,6 +358,7 @@ impl<'buf> NakPduCreatorWithReservedSeqReqsBuf<'buf> {
         calculate_max_segment_requests(max_packet_size, pdu_header)
     }
 
+    /// Constructor.
     pub fn new(
         buf: &'buf mut [u8],
         mut pdu_header: PduHeader,
@@ -371,11 +386,13 @@ impl<'buf> NakPduCreatorWithReservedSeqReqsBuf<'buf> {
 }
 
 impl NakPduCreatorWithReservedSeqReqsBuf<'_> {
+    /// PDU header.
     #[inline]
     pub fn pdu_header(&self) -> &PduHeader {
         &self.pdu_header
     }
 
+    /// Number of segment requests.
     #[inline]
     pub fn num_segment_reqs(&self) -> usize {
         self.num_segment_reqs
@@ -407,6 +424,7 @@ impl NakPduCreatorWithReservedSeqReqsBuf<'_> {
         Ok(())
     }
 
+    /// Length when written to a buffer.
     pub fn len_written(&self) -> usize {
         self.pdu_header.header_len() + self.calc_pdu_datafield_len()
     }
@@ -427,6 +445,7 @@ impl NakPduCreatorWithReservedSeqReqsBuf<'_> {
         &self.buf[segment_req_buf_offset..segment_req_buf_offset + len]
     }
 
+    /// Iterator over all segment requests.
     #[inline]
     pub fn segment_request_iter(&self) -> SegmentRequestIter<'_> {
         SegmentRequestIter::new(
@@ -447,7 +466,7 @@ impl NakPduCreatorWithReservedSeqReqsBuf<'_> {
     ) -> Result<usize, InvalidStartOrEndOfScopeError> {
         self.set_start_and_end_of_scope(start_of_scope, end_of_scope)?;
         let mut current_idx = self.pdu_header.write_to_bytes(self.buf).unwrap();
-        self.buf[current_idx] = FileDirectiveType::NakPdu as u8;
+        self.buf[current_idx] = FileDirectiveType::Nak as u8;
         current_idx += 1;
 
         if self.pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
@@ -613,15 +632,17 @@ impl CfdpPdu for NakPduReader<'_> {
     }
 
     fn file_directive_type(&self) -> Option<FileDirectiveType> {
-        Some(FileDirectiveType::NakPdu)
+        Some(FileDirectiveType::Nak)
     }
 }
 
 impl<'seg_reqs> NakPduReader<'seg_reqs> {
+    /// Constructor from a raw bytestream.
     pub fn new(buf: &'seg_reqs [u8]) -> Result<NakPduReader<'seg_reqs>, PduError> {
         Self::from_bytes(buf)
     }
 
+    /// Constructor from a raw bytestream.
     pub fn from_bytes(buf: &'seg_reqs [u8]) -> Result<NakPduReader<'seg_reqs>, PduError> {
         let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
         let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
@@ -631,13 +652,13 @@ impl<'seg_reqs> NakPduReader<'seg_reqs> {
         let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
             PduError::InvalidDirectiveType {
                 found: buf[current_idx],
-                expected: Some(FileDirectiveType::NakPdu),
+                expected: Some(FileDirectiveType::Nak),
             }
         })?;
-        if directive_type != FileDirectiveType::NakPdu {
+        if directive_type != FileDirectiveType::Nak {
             return Err(PduError::WrongDirectiveType {
                 found: directive_type,
-                expected: FileDirectiveType::AckPdu,
+                expected: FileDirectiveType::Ack,
             });
         }
         current_idx += 1;
@@ -682,14 +703,17 @@ impl<'seg_reqs> NakPduReader<'seg_reqs> {
         })
     }
 
+    /// Start of scope.
     pub fn start_of_scope(&self) -> u64 {
         self.start_of_scope
     }
 
+    /// End of scope.
     pub fn end_of_scope(&self) -> u64 {
         self.end_of_scope
     }
 
+    /// Number of segment requests.
     pub fn num_segment_reqs(&self) -> usize {
         if self.seg_reqs_raw.is_empty() {
             return 0;
@@ -747,10 +771,7 @@ mod tests {
         assert_eq!(nak_pdu.crc_flag(), CrcFlag::NoCrc);
         assert_eq!(nak_pdu.file_flag(), LargeFileFlag::Normal);
         assert_eq!(nak_pdu.pdu_type(), PduType::FileDirective);
-        assert_eq!(
+        assert_eq!(nak_pdu.file_directive_type(), Some(FileDirectiveType::Nak),);
-            nak_pdu.file_directive_type(),
-            Some(FileDirectiveType::NakPdu),
-        );
         assert_eq!(nak_pdu.transmission_mode(), TransmissionMode::Acknowledged);
         assert_eq!(nak_pdu.direction(), Direction::TowardsSender);
         assert_eq!(nak_pdu.source_id(), TEST_SRC_ID.into());
@@ -794,7 +815,7 @@ mod tests {
         verify_raw_header(nak_pdu.pdu_header(), &buf);
         let mut current_idx = nak_pdu.pdu_header().header_len();
         assert_eq!(current_idx + 9, nak_pdu.len_written());
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
@@ -821,7 +842,7 @@ mod tests {
         verify_raw_header(nak_pdu.pdu_header(), &buf);
         let mut current_idx = nak_pdu.pdu_header().header_len();
         assert_eq!(current_idx + 9 + 16, nak_pdu.len_written());
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
@@ -1034,7 +1055,7 @@ mod tests {
         verify_raw_header(&pdu_header, &buf);
         let mut current_idx = pdu_header.header_len();
         assert_eq!(current_idx + 9, len_written);
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
@@ -1060,7 +1081,7 @@ mod tests {
         verify_raw_header(&pdu_header, &buf);
         let mut current_idx = pdu_header.header_len();
         assert_eq!(current_idx + 1 + 8 + 2, len_written);
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
@@ -1087,7 +1108,7 @@ mod tests {
         verify_raw_header(&pdu_header, &buf);
         let mut current_idx = pdu_header.header_len();
         assert_eq!(current_idx + 1 + 16, len_written);
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u64::from_be_bytes(buf[current_idx..current_idx + 8].try_into().unwrap());
@@ -1131,7 +1152,7 @@ mod tests {
         verify_raw_header(&pdu_header, &buf);
         let mut current_idx = pdu_header.header_len();
         assert_eq!(current_idx + 1 + 16, len_written);
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u64::from_be_bytes(buf[current_idx..current_idx + 8].try_into().unwrap());
@@ -1171,7 +1192,7 @@ mod tests {
         verify_raw_header(&pdu_header, &buf);
         let mut current_idx = pdu_header.header_len();
         assert_eq!(current_idx + 1 + 8 + num_segments * 8, len_written);
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
@@ -1227,7 +1248,7 @@ mod tests {
         verify_raw_header(&pdu_header, &buf);
         let mut current_idx = pdu_header.header_len();
         assert_eq!(current_idx + 1 + 16 + num_segments * 16, len_written);
-        assert_eq!(buf[current_idx], FileDirectiveType::NakPdu as u8);
+        assert_eq!(buf[current_idx], FileDirectiveType::Nak as u8);
         current_idx += 1;
         let start_of_scope =
             u64::from_be_bytes(buf[current_idx..current_idx + 8].try_into().unwrap());

src/cfdp/tlv/mod.rs

@@ -19,9 +19,12 @@ 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
@@ -45,7 +48,9 @@ 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.
@@ -68,9 +73,15 @@ pub trait ReadableTlv {
     }
 }
 
+/// 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()];
@@ -79,34 +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
@@ -115,9 +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,
 }
 
@@ -158,8 +189,10 @@ pub struct Tlv<'data> {
 }
 
 impl<'data> Tlv<'data> {
+    /// 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),
@@ -167,6 +200,7 @@ impl<'data> Tlv<'data> {
         })
     }
 
+    /// Constructor for a TLV with a custom type field.
     pub fn new_with_custom_type(
         tlv_type: u8,
         data: &[u8],
@@ -208,6 +242,7 @@ impl<'data> Tlv<'data> {
         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 {
@@ -251,6 +286,7 @@ impl GenericTlv for Tlv<'_> {
     }
 }
 
+/// Component of the TLV module which require [alloc] support.
 #[cfg(feature = "alloc")]
 pub mod alloc_mod {
     use super::*;
@@ -266,6 +302,7 @@ pub mod alloc_mod {
     }
 
     impl TlvOwned {
+        /// Generic constructor.
         pub fn new(tlv_type: TlvType, data: &[u8]) -> Self {
             Self {
                 tlv_type_field: TlvTypeField::Standard(tlv_type),
@@ -273,6 +310,7 @@ pub mod alloc_mod {
             }
         }
 
+        /// 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),
@@ -288,6 +326,7 @@ pub mod alloc_mod {
             }
         }
 
+        /// 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();
@@ -301,6 +340,7 @@ pub mod alloc_mod {
             self.data.len() + 2
         }
 
+        /// Convert to [Tlv]
         pub fn as_tlv(&self) -> Tlv<'_> {
             Tlv {
                 tlv_type_field: self.tlv_type_field,
@@ -349,6 +389,7 @@ pub mod alloc_mod {
     }
 }
 
+/// Entity ID TLV.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -357,6 +398,7 @@ pub struct EntityIdTlv {
 }
 
 impl EntityIdTlv {
+    /// Constructor.
     #[inline]
     pub fn new(entity_id: UnsignedByteField) -> Self {
         Self { entity_id }
@@ -372,21 +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)?;
@@ -478,6 +524,7 @@ impl TryFrom<Tlv<'_>> 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
@@ -511,6 +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> {
@@ -519,14 +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>,
@@ -566,18 +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)
     }
@@ -611,31 +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> {
@@ -720,6 +781,7 @@ impl GenericTlv for FilestoreRequestTlv<'_, '_> {
     }
 }
 
+/// Filestore response TLV.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -751,6 +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,
@@ -779,6 +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
@@ -789,36 +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> {

src/cfdp/tlv/msg_to_user.rs

@@ -8,8 +8,10 @@ use crate::{
 };
 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>,
 }
 
@@ -23,7 +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;
@@ -37,14 +41,16 @@ impl<'data> MsgToUserTlv<'data> {
         }
     }
 
+    /// Is this a standard TLV?
     #[inline]
     pub fn is_standard_tlv(&self) -> bool {
         true
     }
 
+    /// TLV type field.
     #[inline]
-    pub fn tlv_type(&self) -> Option<TlvType> {
+    pub fn tlv_type(&self) -> TlvType {
-        Some(TlvType::MsgToUser)
+        TlvType::MsgToUser
     }
 
     /// Check whether this message is a reserved CFDP message like a Proxy Operation Message.
@@ -85,11 +91,13 @@ impl<'data> MsgToUserTlv<'data> {
         Ok(msg_to_user)
     }
 
+    /// 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()
@@ -102,6 +110,7 @@ impl<'data> MsgToUserTlv<'data> {
 
     delegate!(
         to self.tlv {
+            /// Write the TLV to a byte buffer.
             pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
         }
     );
@@ -142,7 +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)

src/crc.rs

@@ -1,3 +1,7 @@
+//! # 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> =

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();
+        let subservice: MessageSubtypeId = 2.try_into().unwrap();
-        assert_eq!(subservice, Subservice::TmLowSeverityReport);
+        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();
+        let hk_report: MessageSubtypeId =
-        assert_eq!(hk_report, Subservice::TmHkPacket);
+            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;
+        let hk_report_raw = MessageSubtypeId::TmHkPacket;
-        assert_ne!(hk_report_raw, Subservice::TcGenerateOneShotHk);
+        assert_ne!(hk_report_raw, MessageSubtypeId::TcGenerateOneShotHk);
-        assert_eq!(hk_report_raw, Subservice::TmHkPacket);
+        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

@@ -25,53 +25,55 @@ 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,
 }
 
@@ -83,8 +85,11 @@ pub enum PusServiceId {
 #[repr(u8)]
 #[non_exhaustive]
 pub enum PusVersion {
+    /// ESA PUS
     EsaPus = 0,
+    /// PUS A
     PusA = 1,
+    /// PUS C
     PusC = 2,
 }
 
@@ -107,20 +112,33 @@ impl TryFrom<u4> for PusVersion {
 #[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].
@@ -129,15 +147,25 @@ pub type Ptc = PacketTypeCodes;
 #[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,
 }
 
@@ -157,12 +185,15 @@ pub enum PfcReal {
     DoubleMilStd = 4,
 }
 
+/// 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 {
+    /// 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
@@ -172,15 +203,54 @@ pub enum PusError {
     ByteConversion(#[from] ByteConversionError),
 }
 
+/// 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,
+        }
+    }
+}
+
 /// 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 {
+    /// PUS version.
     fn pus_version(&self) -> Result<PusVersion, u4>;
-    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];
+
     /// 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()
@@ -226,6 +296,7 @@ pub(crate) fn user_data_from_raw(
     }
 }
 
+/// 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,
@@ -235,6 +306,8 @@ pub fn verify_crc16_ccitt_false_from_raw_to_pus_error(
         .ok_or(PusError::ChecksumFailure(crc16))
 }
 
+/// 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,
@@ -267,10 +340,15 @@ pub fn verify_crc16_ccitt_false_from_raw_no_table(raw_data: &[u8]) -> bool {
 macro_rules! sp_header_impls {
     () => {
         delegate!(to self.sp_header {
+            /// Set the CCSDS APID.
             #[inline]
             pub fn set_apid(&mut self, apid: u11);
+
+            /// Set the CCSDS sequence count.
             #[inline]
             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);
         });
@@ -289,27 +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>> {
+pub struct GenericEcssEnumWrapper<TYPE: Copy + Into<u64>>(GenericUnsignedByteField<TYPE>);
-    field: 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 {
+    /// Value.
-        self.field.value_typed()
+    pub const fn value(&self) -> TYPE {
+        self.0.value()
     }
 
-    pub fn new(val: TYPE) -> Self {
+    /// Generic constructor.
-        Self {
+    pub const fn new(val: TYPE) -> Self {
-            field: GenericUnsignedByteField::new(val),
+        Self(GenericUnsignedByteField::new(val))
-        }
     }
 }
 
@@ -319,11 +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 {
+    fn value_raw(&self) -> u64 {
-        self.field.value()
+        self.0.value().into()
     }
 }
 
@@ -347,11 +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()
                 }
             }
         )*
@@ -412,6 +492,7 @@ pub trait WritablePusPacket {
         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
@@ -423,6 +504,7 @@ 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))]
@@ -465,7 +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();
@@ -484,7 +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();
@@ -521,7 +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();
@@ -559,7 +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);

src/ecss/scheduling.rs

@@ -3,46 +3,74 @@ 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,
 }
 
@@ -51,7 +79,9 @@ pub enum Subservice {
 #[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,
 }
 
@@ -71,9 +101,13 @@ impl From<bool> for SchedStatus {
 #[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,
 }
 
@@ -99,20 +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();
+        let subservice: MessageSubtypeId = 22u8.try_into().unwrap();
-        assert_eq!(subservice, Subservice::TcCreateScheduleGroup);
+        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/tc.rs

@@ -5,18 +5,18 @@
 //!
 //! ```rust
 //! use spacepackets::SpHeader;
-//! use spacepackets::ecss::tc::{PusTcCreator, PusTcReader, PusTcSecondaryHeader, CreatorConfig};
+//! use spacepackets::ecss::tc::{MessageTypeId, PusTcCreator, PusTcReader, PusTcSecondaryHeader, CreatorConfig};
 //! use arbitrary_int::u11;
 //!
 //! // Create a ping telecommand with no user application data
 //! let pus_tc = PusTcCreator::new_no_app_data(
 //!     SpHeader::new_from_apid(u11::new(0x02)),
-//!     PusTcSecondaryHeader::new_simple(17, 1),
+//!     PusTcSecondaryHeader::new_simple(MessageTypeId::new(17, 1)),
 //!     CreatorConfig::default()
 //! );
 //! println!("{:?}", pus_tc);
-//! assert_eq!(pus_tc.service(), 17);
+//! assert_eq!(pus_tc.service_type_id(), 17);
-//! assert_eq!(pus_tc.subservice(), 1);
+//! assert_eq!(pus_tc.message_subtype_id(), 1);
 //! assert_eq!(pus_tc.apid().value(), 0x02);
 //!
 //! // Serialize TC into a raw buffer
@@ -29,25 +29,25 @@
 //!
 //! // Deserialize from the raw byte representation
 //! let pus_tc_deserialized = PusTcReader::new(&test_buf).expect("Deserialization failed");
-//! assert_eq!(pus_tc.service(), 17);
+//! assert_eq!(pus_tc.service_type_id(), 17);
-//! assert_eq!(pus_tc.subservice(), 1);
+//! assert_eq!(pus_tc.message_subtype_id(), 1);
 //! assert_eq!(pus_tc.apid().value(), 0x02);
 //!
 //! // Alternative builder API
 //! let pus_tc_by_builder = PusTcCreator::builder()
-//!     .with_service(17)
+//!     .with_service_type_id(17)
-//!     .with_subservice(1)
+//!     .with_message_subtype_id(1)
 //!     .with_apid(u11::new(0x02))
 //!     .build();
 //! assert_eq!(pus_tc_by_builder, pus_tc);
 //! ```
 use crate::crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE};
-pub use crate::ecss::CreatorConfig;
 use crate::ecss::{
     crc_from_raw_data, sp_header_impls, user_data_from_raw,
     verify_crc16_ccitt_false_from_raw_to_pus_error, PusError, PusPacket, PusVersion,
     WritablePusPacket,
 };
+pub use crate::ecss::{CreatorConfig, MessageTypeId};
 use crate::{ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, CCSDS_HEADER_LEN};
 use crate::{PacketId, PacketSequenceControl, SpHeader};
 use arbitrary_int::{u11, u14, u3, u4};
@@ -57,10 +57,6 @@ use delegate::delegate;
 use serde::{Deserialize, Serialize};
 use zerocopy::{FromBytes, IntoBytes};
 
-// Is necessary for some reason, possibly bug.
-#[cfg(feature = "defmt")]
-use arbitrary_int::traits::Integer;
-
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 
@@ -68,26 +64,33 @@ use super::verify_crc16_ccitt_false_from_raw_to_pus_error_no_table;
 
 /// PUS C secondary header length is fixed
 pub const PUC_TC_SECONDARY_HEADER_LEN: usize = size_of::<zc::PusTcSecondaryHeader>();
+/// Minimum PUS C secondary header length without application data.
 pub const PUS_TC_MIN_LEN_WITHOUT_APP_DATA: usize = CCSDS_HEADER_LEN + PUC_TC_SECONDARY_HEADER_LEN;
 const PUS_VERSION: PusVersion = PusVersion::PusC;
 
 /// Marker trait for PUS telecommand structures.
 pub trait IsPusTelecommand {}
 
+/// Acknowledgement flags for PUS telecommands.
 #[bitbybit::bitfield(u4, default = 0b0000, debug, defmt_bitfields(feature = "defmt"))]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[derive(PartialEq, Eq)]
 pub struct AckFlags {
+    /// Acceptance must be acknowledged.
     #[bit(3, rw)]
     acceptance: bool,
+    /// Start must be acknowledged.
     #[bit(2, rw)]
     start: bool,
+    /// Progress must be acknowledged.
     #[bit(1, rw)]
     progress: bool,
+    /// Completion must be acknowledged.
     #[bit(0, rw)]
     completion: bool,
 }
 
+/// Constant to acknowledge all TC handling phases.
 pub const ACK_ALL: AckFlags = AckFlags::builder()
     .with_acceptance(true)
     .with_start(true)
@@ -96,30 +99,49 @@ pub const ACK_ALL: AckFlags = AckFlags::builder()
     .build();
 
 impl AckFlags {
+    /// Constant to acknowledge all TC handling phases.
     pub const ALL: Self = ACK_ALL;
 }
 
+/// Generic trait for PUS TC secondary header access.
 pub trait GenericPusTcSecondaryHeader {
+    /// PUS version.
     fn pus_version(&self) -> Result<PusVersion, u4>;
+    /// Acknowledgement flags.
     fn ack_flags(&self) -> AckFlags;
-    fn service(&self) -> u8;
+    /// Message type ID.
-    fn subservice(&self) -> u8;
+    fn message_type_id(&self) -> MessageTypeId;
+    /// Source ID.
     fn source_id(&self) -> u16;
+
+    /// 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
+    }
 }
 
+/// [zerocopy] support.
 pub mod zc {
     use crate::ecss::tc::{AckFlags, GenericPusTcSecondaryHeader};
-    use crate::ecss::{PusError, PusVersion};
+    use crate::ecss::{MessageTypeId, PusError, PusVersion};
     use arbitrary_int::traits::Integer;
     use arbitrary_int::u4;
     use zerocopy::{FromBytes, Immutable, IntoBytes, NetworkEndian, Unaligned, U16};
 
+    /// PUS TC secondary header.
     #[derive(FromBytes, IntoBytes, Immutable, Unaligned)]
     #[repr(C)]
     pub struct PusTcSecondaryHeader {
         version_ack: u8,
-        service: u8,
+        service_type_id: u8,
-        subservice: u8,
+        message_subtype_id: u8,
         source_id: U16<NetworkEndian>,
     }
 
@@ -131,8 +153,8 @@ pub mod zc {
             }
             Ok(PusTcSecondaryHeader {
                 version_ack: ((value.version as u8) << 4) | value.ack_flags.raw_value().as_u8(),
-                service: value.service,
+                service_type_id: value.service_type_id(),
-                subservice: value.subservice,
+                message_subtype_id: value.message_subtype_id(),
                 source_id: U16::from(value.source_id),
             })
         }
@@ -150,13 +172,22 @@ pub mod zc {
         }
 
         #[inline]
-        fn service(&self) -> u8 {
+        /// Message type ID.
-            self.service
+        fn message_type_id(&self) -> MessageTypeId {
+            MessageTypeId {
+                type_id: self.service_type_id,
+                subtype_id: self.message_subtype_id,
+            }
         }
 
         #[inline]
-        fn subservice(&self) -> u8 {
+        fn service_type_id(&self) -> u8 {
-            self.subservice
+            self.service_type_id
+        }
+
+        #[inline]
+        fn message_subtype_id(&self) -> u8 {
+            self.message_subtype_id
         }
 
         #[inline]
@@ -166,14 +197,18 @@ pub mod zc {
     }
 }
 
+/// PUS C secondary header for telecommands.
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTcSecondaryHeader {
-    pub service: u8,
+    /// Message type ID.
-    pub subservice: u8,
+    pub message_type_id: MessageTypeId,
+    /// Source ID.
     pub source_id: u16,
+    /// Acknowledgement flags.
     pub ack_flags: AckFlags,
+    /// PUS version.
     pub version: PusVersion,
 }
 
@@ -189,13 +224,8 @@ impl GenericPusTcSecondaryHeader for PusTcSecondaryHeader {
     }
 
     #[inline]
-    fn service(&self) -> u8 {
+    fn message_type_id(&self) -> MessageTypeId {
-        self.service
+        self.message_type_id
-    }
-
-    #[inline]
-    fn subservice(&self) -> u8 {
-        self.subservice
     }
 
     #[inline]
@@ -209,8 +239,7 @@ impl TryFrom<zc::PusTcSecondaryHeader> for PusTcSecondaryHeader {
 
     fn try_from(value: zc::PusTcSecondaryHeader) -> Result<Self, Self::Error> {
         Ok(PusTcSecondaryHeader {
-            service: value.service(),
+            message_type_id: value.message_type_id(),
-            subservice: value.subservice(),
             source_id: value.source_id(),
             ack_flags: value.ack_flags(),
             version: PUS_VERSION,
@@ -219,24 +248,25 @@ impl TryFrom<zc::PusTcSecondaryHeader> for PusTcSecondaryHeader {
 }
 
 impl PusTcSecondaryHeader {
+    /// Header length constant.
     pub const HEADER_LEN: usize = PUC_TC_SECONDARY_HEADER_LEN;
 
+    /// Simple constructor which only requires the [MessageTypeId].
     #[inline]
-    pub fn new_simple(service: u8, subservice: u8) -> Self {
+    pub fn new_simple(message_type_id: MessageTypeId) -> Self {
         PusTcSecondaryHeader {
-            service,
+            message_type_id,
-            subservice,
             ack_flags: ACK_ALL,
             source_id: 0,
             version: PusVersion::PusC,
         }
     }
 
+    /// General constructor.
     #[inline]
-    pub fn new(service: u8, subservice: u8, ack_flags: AckFlags, source_id: u16) -> Self {
+    pub fn new(message_type_id: MessageTypeId, ack_flags: AckFlags, source_id: u16) -> Self {
         PusTcSecondaryHeader {
-            service,
+            message_type_id,
-            subservice,
             ack_flags,
             source_id,
             version: PusVersion::PusC,
@@ -257,6 +287,7 @@ impl PusTcSecondaryHeader {
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTcCreator<'app_data> {
     sp_header: SpHeader,
+    /// Secondary header.
     pub sec_header: PusTcSecondaryHeader,
     app_data: &'app_data [u8],
     has_checksum: bool,
@@ -299,19 +330,19 @@ impl<'app_data> PusTcCreator<'app_data> {
     #[inline]
     pub fn new_simple(
         sph: SpHeader,
-        service: u8,
+        message_type_id: MessageTypeId,
-        subservice: u8,
         app_data: &'app_data [u8],
         packet_config: CreatorConfig,
     ) -> Self {
         Self::new(
             sph,
-            PusTcSecondaryHeader::new(service, subservice, ACK_ALL, 0),
+            PusTcSecondaryHeader::new(message_type_id, ACK_ALL, 0),
             app_data,
             packet_config,
         )
     }
 
+    /// Constructor for a PUS TC packet without application data.
     #[inline]
     pub fn new_no_app_data(
         sp_header: SpHeader,
@@ -321,40 +352,48 @@ impl<'app_data> PusTcCreator<'app_data> {
         Self::new(sp_header, sec_header, &[], packet_config)
     }
 
+    /// Get a builder whih allows building [Self] step-by-step.
     pub fn builder<'a>() -> PusTcBuilder<'a> {
         PusTcBuilder::default()
     }
 
+    /// Space packet header.
     #[inline]
     pub fn sp_header(&self) -> &SpHeader {
         &self.sp_header
     }
 
+    /// Mutable access to the space packet header.
     #[inline]
     pub fn sp_header_mut(&mut self) -> &mut SpHeader {
         &mut self.sp_header
     }
 
+    /// Service type ID.
     #[inline]
-    pub fn service(&self) -> u8 {
+    pub fn service_type_id(&self) -> u8 {
-        self.sec_header.service
+        self.sec_header.service_type_id()
     }
 
+    /// Message subtype ID.
     #[inline]
-    pub fn subservice(&self) -> u8 {
+    pub fn message_subtype_id(&self) -> u8 {
-        self.sec_header.subservice
+        self.sec_header.message_subtype_id()
     }
 
+    /// Application Process ID (APID).
     #[inline]
     pub fn apid(&self) -> u11 {
         self.sp_header.packet_id.apid
     }
 
+    /// Set acknowledgement flags.
     #[inline]
     pub fn set_ack_flags(&mut self, ack_flags: AckFlags) {
         self.sec_header.ack_flags = ack_flags;
     }
 
+    /// Set the source ID.
     #[inline]
     pub fn set_source_id(&mut self, source_id: u16) {
         self.sec_header.source_id = source_id;
@@ -396,11 +435,13 @@ impl<'app_data> PusTcCreator<'app_data> {
         digest.finalize()
     }
 
+    /// Current packet has a checksum.
     #[inline]
     pub fn has_checksum(&self) -> bool {
         self.has_checksum
     }
 
+    /// Append the raw PUS byte representation to a provided vector.
     #[cfg(feature = "alloc")]
     pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> usize {
         let sph_zc = crate::zc::SpHeader::from(self.sp_header);
@@ -513,9 +554,11 @@ impl PusPacket for PusTcCreator<'_> {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
         #[inline]
-        fn subservice(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+        #[inline]
+        fn message_subtype_id(&self) -> u8;
     });
 
     #[inline]
@@ -541,9 +584,11 @@ impl GenericPusTcSecondaryHeader for PusTcCreator<'_> {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
         #[inline]
-        fn subservice(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+        #[inline]
+        fn message_subtype_id(&self) -> u8;
         #[inline]
         fn source_id(&self) -> u16;
         #[inline]
@@ -638,6 +683,7 @@ impl<'buf> PusTcCreatorWithReservedAppData<'buf> {
         })
     }
 
+    /// Length of the full packet written into a buffer.
     #[inline]
     pub const fn len_written(&self) -> usize {
         self.full_len
@@ -665,6 +711,7 @@ impl<'buf> PusTcCreatorWithReservedAppData<'buf> {
         &self.buf[self.app_data_offset..end_index]
     }
 
+    /// Length of the application data.
     #[inline]
     pub fn app_data_len(&self) -> usize {
         let mut len = self.full_len - self.app_data_offset;
@@ -727,6 +774,7 @@ pub struct PusTcBuilder<'a> {
 }
 
 impl PusTcBuilder<'_> {
+    /// Constructor.
     pub fn new() -> Self {
         Self {
             sp_header: SpHeader::new(
@@ -734,12 +782,13 @@ impl PusTcBuilder<'_> {
                 PacketSequenceControl::new(SequenceFlags::Unsegmented, u14::new(0)),
                 0,
             ),
-            sec_header: PusTcSecondaryHeader::new(0, 0, ACK_ALL, 0),
+            sec_header: PusTcSecondaryHeader::new(MessageTypeId::new(0, 0), ACK_ALL, 0),
             app_data: &[],
             has_checksum: true,
         }
     }
 
+    /// Set the packet ID.
     #[inline]
     pub fn with_packet_id(mut self, mut packet_id: PacketId) -> Self {
         packet_id.packet_type = PacketType::Tc;
@@ -747,48 +796,63 @@ impl PusTcBuilder<'_> {
         self
     }
 
+    /// Set the packet sequence control.
     #[inline]
     pub fn with_packet_sequence_control(mut self, psc: PacketSequenceControl) -> Self {
         self.sp_header.psc = psc;
         self
     }
 
+    /// Set the sequence count.
     #[inline]
     pub fn with_sequence_count(mut self, seq_count: u14) -> Self {
         self.sp_header.psc.seq_count = seq_count;
         self
     }
 
+    /// Set the message type ID.
     #[inline]
-    pub fn with_service(mut self, service: u8) -> Self {
+    pub fn with_message_type_id(mut self, message_type: MessageTypeId) -> Self {
-        self.sec_header.service = service;
+        self.sec_header.message_type_id = message_type;
         self
     }
 
+    /// Set the service type ID.
     #[inline]
-    pub fn with_subservice(mut self, service: u8) -> Self {
+    pub fn with_service_type_id(mut self, service: u8) -> Self {
-        self.sec_header.subservice = service;
+        self.sec_header.message_type_id.type_id = service;
         self
     }
 
+    /// Set the message subtype ID.
+    #[inline]
+    pub fn with_message_subtype_id(mut self, subtype_id: u8) -> Self {
+        self.sec_header.message_type_id.subtype_id = subtype_id;
+        self
+    }
+
+    /// Set the source ID.
     #[inline]
     pub fn with_source_id(mut self, source_id: u16) -> Self {
         self.sec_header.source_id = source_id;
         self
     }
 
+    /// Set the acknowledgmenet flags.
     #[inline]
     pub fn with_ack_flags(mut self, ack_flags: AckFlags) -> Self {
         self.sec_header.ack_flags = ack_flags;
         self
     }
 
+    /// Set the Application Process ID (APID).
     #[inline]
     pub fn with_apid(mut self, apid: u11) -> Self {
         self.sp_header.packet_id.set_apid(apid);
         self
     }
 
+    /// Enable or disable the checksum.
     #[inline]
     pub fn with_checksum(mut self, has_checksum: bool) -> Self {
         self.has_checksum = has_checksum;
@@ -803,6 +867,7 @@ impl Default for PusTcBuilder<'_> {
 }
 
 impl<'a> PusTcBuilder<'a> {
+    /// Constructor.
     pub fn build(self) -> PusTcCreator<'a> {
         PusTcCreator::new(
             self.sp_header,
@@ -815,6 +880,7 @@ impl<'a> PusTcBuilder<'a> {
         )
     }
 
+    /// Application data slice.
     #[inline]
     pub fn with_app_data(mut self, app_data: &'a [u8]) -> Self {
         self.app_data = app_data;
@@ -923,26 +989,31 @@ impl<'raw_data> PusTcReader<'raw_data> {
         })
     }
 
+    /// Application data slice.
     #[inline]
     pub fn app_data(&self) -> &[u8] {
         self.user_data()
     }
 
+    /// Full raw data slice.
     #[inline]
     pub fn raw_data(&self) -> &[u8] {
         self.raw_data
     }
 
+    /// Length of the packed data.
     #[inline]
     pub fn len_packed(&self) -> usize {
         self.sp_header.packet_len()
     }
 
+    /// Space packet header.
     #[inline]
     pub fn sp_header(&self) -> &SpHeader {
         &self.sp_header
     }
 
+    /// CRC16 checksum if present.
     #[inline]
     pub fn crc16(&self) -> Option<u16> {
         self.crc16
@@ -974,9 +1045,11 @@ impl PusPacket for PusTcReader<'_> {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
         #[inline]
-        fn subservice(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+        #[inline]
+        fn message_subtype_id(&self) -> u8;
     });
 
     fn has_checksum(&self) -> bool {
@@ -999,9 +1072,11 @@ impl GenericPusTcSecondaryHeader for PusTcReader<'_> {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
         #[inline]
-        fn subservice(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+        #[inline]
+        fn message_subtype_id(&self) -> u8;
         #[inline]
         fn source_id(&self) -> u16;
         #[inline]
@@ -1042,13 +1117,13 @@ mod tests {
 
     fn base_ping_tc_full_ctor() -> PusTcCreator<'static> {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
-        let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
+        let tc_header = PusTcSecondaryHeader::new_simple(MessageTypeId::new(17, 1));
         PusTcCreator::new_no_app_data(sph, tc_header, CreatorConfig::default())
     }
 
     fn base_ping_tc_full_ctor_no_checksum() -> PusTcCreator<'static> {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
-        let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
+        let tc_header = PusTcSecondaryHeader::new_simple(MessageTypeId::new(17, 1));
         PusTcCreator::new_no_app_data(
             sph,
             tc_header,
@@ -1061,21 +1136,26 @@ mod tests {
 
     fn base_ping_tc_simple_ctor() -> PusTcCreator<'static> {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
-        PusTcCreator::new_simple(sph, 17, 1, &[], CreatorConfig::default())
+        PusTcCreator::new_simple(
+            sph,
+            MessageTypeId::new(17, 1),
+            &[],
+            CreatorConfig::default(),
+        )
     }
 
     fn base_ping_tc_with_builder(alt_api: bool) -> PusTcCreator<'static> {
         if alt_api {
             return PusTcCreator::builder()
-                .with_service(17)
+                .with_service_type_id(17)
-                .with_subservice(1)
+                .with_message_subtype_id(1)
                 .with_apid(u11::new(0x02))
                 .with_sequence_count(u14::new(0x34))
                 .build();
         }
         PusTcBuilder::new()
-            .with_service(17)
+            .with_service_type_id(17)
-            .with_subservice(1)
+            .with_message_subtype_id(1)
             .with_apid(u11::new(0x02))
             .with_sequence_count(u14::new(0x34))
             .build()
@@ -1085,8 +1165,7 @@ mod tests {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
         PusTcCreator::new_simple(
             sph,
-            17,
+            MessageTypeId::new(17, 1),
-            1,
             &[],
             CreatorConfig {
                 set_ccsds_len: true,
@@ -1102,8 +1181,7 @@ mod tests {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
         PusTcCreator::new_simple(
             sph,
-            17,
+            MessageTypeId::new(17, 1),
-            1,
             app_data,
             CreatorConfig {
                 set_ccsds_len: true,
@@ -1234,7 +1312,7 @@ mod tests {
     #[test]
     fn test_deserialization_alt_ctor() {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
-        let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
+        let tc_header = PusTcSecondaryHeader::new_simple(MessageTypeId::new(17, 1));
         let mut test_buf: [u8; 32] = [0; 32];
         let mut pus_tc =
             PusTcCreatorWithReservedAppData::new(&mut test_buf, sph, tc_header, 0, true).unwrap();
@@ -1289,8 +1367,7 @@ mod tests {
         let sph = SpHeader::new_for_unseg_tc(u11::new(0x02), u14::new(0x34), 0);
         let mut tc = PusTcCreator::new_simple(
             sph,
-            17,
+            MessageTypeId::new(17, 1),
-            1,
             &[],
             CreatorConfig {
                 set_ccsds_len: false,
@@ -1517,10 +1594,10 @@ mod tests {
     }
 
     fn verify_test_tc_generic(tc: &(impl PusPacket + GenericPusTcSecondaryHeader)) {
-        assert_eq!(PusPacket::service(tc), 17);
+        assert_eq!(PusPacket::service_type_id(tc), 17);
-        assert_eq!(GenericPusTcSecondaryHeader::service(tc), 17);
+        assert_eq!(GenericPusTcSecondaryHeader::service_type_id(tc), 17);
-        assert_eq!(PusPacket::subservice(tc), 1);
+        assert_eq!(PusPacket::message_subtype_id(tc), 1);
-        assert_eq!(GenericPusTcSecondaryHeader::subservice(tc), 1);
+        assert_eq!(GenericPusTcSecondaryHeader::message_subtype_id(tc), 1);
         assert!(tc.sec_header_flag());
         assert_eq!(PusPacket::pus_version(tc).unwrap(), PusC);
         assert_eq!(tc.seq_count().value(), 0x34);
@@ -1650,8 +1727,8 @@ mod tests {
                 SequenceFlags::Unsegmented,
                 u14::new(0x34),
             ))
-            .with_service(17)
+            .with_service_type_id(17)
-            .with_subservice(1)
+            .with_message_subtype_id(1)
             .with_ack_flags(AckFlags::new_with_raw_value(u4::new(0b1010)))
             .with_source_id(0x2f2f)
             .with_checksum(false)
@@ -1660,7 +1737,7 @@ mod tests {
         assert_eq!(tc.sequence_flags(), SequenceFlags::Unsegmented);
         assert_eq!(tc.apid().value(), 0x02);
         assert_eq!(tc.packet_type(), PacketType::Tc);
-        assert_eq!(tc.service(), 17);
+        assert_eq!(tc.service_type_id(), 17);
-        assert_eq!(tc.subservice(), 1);
+        assert_eq!(tc.message_subtype_id(), 1);
     }
 }

src/ecss/tc_pus_a.rs

@@ -15,8 +15,8 @@
 //!     true
 //! );
 //! println!("{:?}", pus_tc);
-//! assert_eq!(pus_tc.service(), 17);
+//! assert_eq!(pus_tc.service_type_id(), 17);
-//! assert_eq!(pus_tc.subservice(), 1);
+//! assert_eq!(pus_tc.message_subtype_id(), 1);
 //! assert_eq!(pus_tc.apid().value(), 0x02);
 //!
 //! // Serialize TC into a raw buffer
@@ -29,15 +29,15 @@
 //!
 //! // Deserialize from the raw byte representation. No source ID, 0 spare bytes.
 //! let pus_tc_deserialized = PusTcReader::new(&test_buf, None, 0).expect("Deserialization failed");
-//! assert_eq!(pus_tc.service(), 17);
+//! assert_eq!(pus_tc.service_type_id(), 17);
-//! assert_eq!(pus_tc.subservice(), 1);
+//! assert_eq!(pus_tc.message_subtype_id(), 1);
 //! assert_eq!(pus_tc.apid().value(), 0x02);
 //! ```
 use crate::crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE};
 use crate::ecss::tc::{AckFlags, ACK_ALL};
 use crate::ecss::{
     crc_from_raw_data, sp_header_impls, user_data_from_raw,
-    verify_crc16_ccitt_false_from_raw_to_pus_error, PusError, PusPacket, PusVersion,
+    verify_crc16_ccitt_false_from_raw_to_pus_error, MessageTypeId, PusError, PusPacket, PusVersion,
     WritablePusPacket,
 };
 use crate::util::{UnsignedByteField, UnsignedEnum};
@@ -74,33 +74,49 @@ enum AckOpts {
 
 /// Assuming 8 bytes of source ID and 7 bytes of spare.
 pub const MAX_SEC_HEADER_LEN: usize = 18;
+/// Maximum allowed number of space bytes.
 pub const MAX_SPARE_BYTES: usize = 7;
 
+/// Invalid number of spare bytes which must be between 0 and 7.
 #[derive(Debug, Eq, PartialEq, Copy, Clone, thiserror::Error)]
 #[error("invalid number of spare bytes, must be between 0 and 7")]
 pub struct InvalidNumberOfSpareBytesError;
 
+/// PUS version error.
 #[derive(Debug, Eq, PartialEq, Copy, Clone, thiserror::Error)]
 #[error("invalid version, expected PUS A (1), got {0}")]
 pub struct VersionError(pub u8);
 
+/// Trait for accessing PUS Telecommand secondary header fields.
 pub trait GenericPusTcSecondaryHeader {
+    /// PUS version number.
     fn pus_version(&self) -> Result<PusVersion, u4>;
+    /// Acknowledgment flags.
     fn ack_flags(&self) -> AckFlags;
+    /// Service type identifier.
     fn service(&self) -> u8;
+    /// Subservice type identifier.
     fn subservice(&self) -> u8;
+    /// Source ID.
     fn source_id(&self) -> Option<UnsignedByteField>;
+    /// Number of spare bytes.
     fn spare_bytes(&self) -> usize;
 }
 
+/// PUS TC secondary header.
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTcSecondaryHeader {
+    /// Service type identifier.
     pub service: u8,
+    /// Subservice type identifier.
     pub subservice: u8,
+    /// Source ID.
     pub source_id: Option<UnsignedByteField>,
+    /// Acknowledgment flags.
     pub ack: AckFlags,
+    /// PUS version.
     pub version: PusVersion,
     spare_bytes: usize,
 }
@@ -138,6 +154,8 @@ impl GenericPusTcSecondaryHeader for PusTcSecondaryHeader {
 }
 
 impl PusTcSecondaryHeader {
+    /// Constructor which allows modifying the service and subservice and sets
+    /// default values for the other fields.
     #[inline]
     pub fn new_simple(service: u8, subservice: u8) -> Self {
         PusTcSecondaryHeader {
@@ -150,6 +168,7 @@ impl PusTcSecondaryHeader {
         }
     }
 
+    /// Generic constructor.
     #[inline]
     pub fn new(
         service: u8,
@@ -176,6 +195,7 @@ impl PusTcSecondaryHeader {
         self.spare_bytes = spare_bytes;
     }
 
+    /// Length of the written secondary header in bytes.
     pub fn written_len(&self) -> usize {
         let mut len = 3 + self.spare_bytes;
         if let Some(source_id) = self.source_id {
@@ -184,6 +204,7 @@ impl PusTcSecondaryHeader {
         len
     }
 
+    /// Converts the secondary header into a vector of bytes.
     #[cfg(feature = "alloc")]
     pub fn to_vec(&self) -> Result<Vec<u8>, ByteConversionError> {
         let mut buf = alloc::vec![0; self.written_len()];
@@ -191,6 +212,7 @@ impl PusTcSecondaryHeader {
         Ok(buf)
     }
 
+    /// Write the secondary header to a provided buffer.
     pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.written_len() {
             return Err(ByteConversionError::ToSliceTooSmall {
@@ -216,6 +238,7 @@ impl PusTcSecondaryHeader {
         Ok(current_idx)
     }
 
+    /// Read the secondary header from a raw byte slice.
     pub fn from_bytes(
         data: &[u8],
         source_id_size: Option<usize>,
@@ -268,6 +291,7 @@ impl PusTcSecondaryHeader {
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTcCreator<'app_data> {
     sp_header: SpHeader,
+    /// Secondary header.
     pub sec_header: PusTcSecondaryHeader,
     app_data: &'app_data [u8],
 }
@@ -323,6 +347,7 @@ impl<'app_data> PusTcCreator<'app_data> {
         )
     }
 
+    /// Constructor without application data.
     #[inline]
     pub fn new_no_app_data(
         sp_header: SpHeader,
@@ -332,26 +357,31 @@ impl<'app_data> PusTcCreator<'app_data> {
         Self::new(sp_header, sec_header, &[], set_ccsds_len)
     }
 
+    /// Space packet header.
     #[inline]
     pub fn sp_header(&self) -> &SpHeader {
         &self.sp_header
     }
 
+    /// Mutable access to the space packet header.
     #[inline]
     pub fn sp_header_mut(&mut self) -> &mut SpHeader {
         &mut self.sp_header
     }
 
+    /// Set the acknowledgment flags.
     #[inline]
     pub fn set_ack_field(&mut self, ack: AckFlags) {
         self.sec_header.ack = ack;
     }
 
+    /// Set the source ID.
     #[inline]
     pub fn set_source_id(&mut self, source_id: Option<UnsignedByteField>) {
         self.sec_header.source_id = source_id;
     }
 
+    /// Application data slice.
     #[inline]
     pub fn app_data(&'app_data self) -> &'app_data [u8] {
         self.user_data()
@@ -397,6 +427,7 @@ impl<'app_data> PusTcCreator<'app_data> {
         digest.finalize()
     }
 
+    /// Append the raw PUS byte representation to a provided vector.
     #[cfg(feature = "alloc")]
     pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> usize {
         let sph_zc = crate::zc::SpHeader::from(self.sp_header);
@@ -499,11 +530,23 @@ impl PusPacket for PusTcCreator<'_> {
     delegate!(to self.sec_header {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
-        #[inline]
-        fn service(&self) -> u8;
-        #[inline]
-        fn subservice(&self) -> u8;
     });
+    #[inline]
+    fn message_type_id(&self) -> MessageTypeId {
+        MessageTypeId {
+            type_id: self.service_type_id(),
+            subtype_id: self.message_subtype_id(),
+        }
+    }
+    #[inline]
+    fn service_type_id(&self) -> u8 {
+        self.sec_header.service
+    }
+
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.sec_header.subservice
+    }
 
     #[inline]
     fn user_data(&self) -> &[u8] {
@@ -604,6 +647,7 @@ impl<'buf> PusTcCreatorWithReservedAppData<'buf> {
         })
     }
 
+    /// Length of the written TC packet.
     #[inline]
     pub const fn len_written(&self) -> usize {
         self.full_len
@@ -621,6 +665,7 @@ impl<'buf> PusTcCreatorWithReservedAppData<'buf> {
         &self.buf[self.app_data_offset..self.full_len - 2]
     }
 
+    /// Application data length.
     #[inline]
     pub fn app_data_len(&self) -> usize {
         self.full_len - 2 - self.app_data_offset
@@ -745,26 +790,31 @@ impl<'raw_data> PusTcReader<'raw_data> {
         })
     }
 
+    /// Application data slice.
     #[inline]
     pub fn app_data(&self) -> &[u8] {
         self.user_data()
     }
 
+    /// Full raw data slice.
     #[inline]
     pub fn raw_data(&self) -> &[u8] {
         self.raw_data
     }
 
+    /// Length of the packed PUS TC packet in bytes.
     #[inline]
     pub fn len_packed(&self) -> usize {
         self.sp_header.packet_len()
     }
 
+    /// Space packet header.
     #[inline]
     pub fn sp_header(&self) -> &SpHeader {
         &self.sp_header
     }
 
+    /// CRC16 checksum value.
     #[inline]
     pub fn crc16(&self) -> u16 {
         self.crc16
@@ -793,14 +843,28 @@ impl CcsdsPacket for PusTcReader<'_> {
 
 impl PusPacket for PusTcReader<'_> {
     delegate!(to self.sec_header {
-        #[inline]
-        fn service(&self) -> u8;
-        #[inline]
-        fn subservice(&self) -> u8;
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
     });
 
+    #[inline]
+    fn message_type_id(&self) -> MessageTypeId {
+        MessageTypeId {
+            type_id: self.service_type_id(),
+            subtype_id: self.message_subtype_id(),
+        }
+    }
+
+    #[inline]
+    fn service_type_id(&self) -> u8 {
+        self.sec_header.service
+    }
+
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.sec_header.subservice
+    }
+
     #[inline]
     fn has_checksum(&self) -> bool {
         true
@@ -1229,9 +1293,9 @@ mod tests {
     }
 
     fn verify_test_tc_generic(tc: &(impl PusPacket + GenericPusTcSecondaryHeader)) {
-        assert_eq!(PusPacket::service(tc), 17);
+        assert_eq!(PusPacket::service_type_id(tc), 17);
         assert_eq!(GenericPusTcSecondaryHeader::service(tc), 17);
-        assert_eq!(PusPacket::subservice(tc), 1);
+        assert_eq!(PusPacket::message_subtype_id(tc), 1);
         assert_eq!(GenericPusTcSecondaryHeader::subservice(tc), 1);
         assert!(tc.sec_header_flag());
         assert_eq!(PusPacket::pus_version(tc).unwrap(), PusVersion::PusA);

src/ecss/tm.rs

@@ -6,7 +6,7 @@
 //! ```rust
 //! use spacepackets::time::cds::CdsTime;
 //! use spacepackets::SpHeader;
-//! use spacepackets::ecss::tm::{PusTmCreator, PusTmReader, PusTmSecondaryHeader, CreatorConfig};
+//! use spacepackets::ecss::tm::{MessageTypeId, PusTmCreator, PusTmReader, PusTmSecondaryHeader, CreatorConfig};
 //! use arbitrary_int::u11;
 //!
 //! let mut time_buf: [u8; 7] = [0; 7];
@@ -17,12 +17,12 @@
 //! // Create a ping telemetry with no user source data
 //! let ping_tm = PusTmCreator::new_no_source_data(
 //!     SpHeader::new_from_apid(u11::new(0x02)),
-//!     PusTmSecondaryHeader::new_simple(17, 2, &time_buf),
+//!     PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), &time_buf),
 //!     CreatorConfig::default()
 //! );
 //! println!("{:?}", ping_tm);
-//! assert_eq!(ping_tm.service(), 17);
+//! assert_eq!(ping_tm.service_type_id(), 17);
-//! assert_eq!(ping_tm.subservice(), 2);
+//! assert_eq!(ping_tm.message_subtype_id(), 2);
 //! assert_eq!(ping_tm.apid().value(), 0x02);
 //!
 //! // Serialize TM into a raw buffer
@@ -36,27 +36,27 @@
 //! // Deserialize from the raw byte representation
 //! let ping_tm_reader = PusTmReader::new(&test_buf, 7).expect("Deserialization failed");
 //! assert_eq!(written_size, ping_tm_reader.packet_len());
-//! assert_eq!(ping_tm_reader.service(), 17);
+//! assert_eq!(ping_tm_reader.service_type_id(), 17);
-//! assert_eq!(ping_tm_reader.subservice(), 2);
+//! assert_eq!(ping_tm_reader.message_subtype_id(), 2);
 //! assert_eq!(ping_tm_reader.apid().value(), 0x02);
 //! assert_eq!(ping_tm_reader.timestamp(), &time_buf);
 //!
 //! // Alternative builder API
 //! let pus_tm_by_builder = PusTmCreator::builder()
-//!     .with_service(17)
+//!     .with_service_type_id(17)
-//!     .with_subservice(2)
+//!     .with_message_subtype_id(2)
 //!     .with_apid(u11::new(0x02))
 //!     .with_timestamp(&time_buf)
 //!     .build();
 //! assert_eq!(pus_tm_by_builder, ping_tm);
 //! ```
 use crate::crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE};
-pub use crate::ecss::CreatorConfig;
 use crate::ecss::{
     calc_pus_crc16, crc_from_raw_data, sp_header_impls, user_data_from_raw,
     verify_crc16_ccitt_false_from_raw_to_pus_error, PusError, PusPacket, PusVersion,
     WritablePusPacket,
 };
+pub use crate::ecss::{CreatorConfig, MessageTypeId};
 use crate::{
     ByteConversionError, CcsdsPacket, PacketId, PacketSequenceControl, PacketType, SequenceFlags,
     SpHeader, CCSDS_HEADER_LEN, MAX_APID,
@@ -78,40 +78,63 @@ use self::zc::PusTmSecHeaderWithoutTimestamp;
 
 use super::verify_crc16_ccitt_false_from_raw_to_pus_error_no_table;
 
+/// Marker trait for PUS telemetry packets.
 pub trait IsPusTelemetry {}
 
 /// Length without timestamp
 pub const PUS_TM_MIN_SEC_HEADER_LEN: usize = 7;
+/// Minimum length of a PUS telemetry packet without source data and timestamp
 pub const PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA: usize = CCSDS_HEADER_LEN + PUS_TM_MIN_SEC_HEADER_LEN;
 
+/// Generic properties of a PUS TM secondary header.
 pub trait GenericPusTmSecondaryHeader {
+    /// PUS version.
     fn pus_version(&self) -> Result<PusVersion, u4>;
+    /// Spacecraft time reference status.
     fn sc_time_ref_status(&self) -> u4;
-    fn service(&self) -> u8;
+    /// Message type ID.
-    fn subservice(&self) -> u8;
+    fn message_type_id(&self) -> MessageTypeId;
-    fn msg_counter(&self) -> u16;
+    /// Message counter for the message type.
+    fn msg_type_counter(&self) -> u16;
+
+    /// Destination ID.
     fn dest_id(&self) -> u16;
+
+    /// 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
+    }
 }
 
+/// [zerocopy] support module.
 pub mod zc {
     use super::GenericPusTmSecondaryHeader;
-    use crate::ecss::{PusError, PusVersion};
+    use crate::ecss::{MessageTypeId, PusError, PusVersion};
     use arbitrary_int::{traits::Integer as _, u4};
     use zerocopy::{FromBytes, Immutable, IntoBytes, NetworkEndian, Unaligned, U16};
 
+    /// PUS TM secondary header without a timestamp.
     #[derive(FromBytes, IntoBytes, Immutable, Unaligned)]
     #[repr(C)]
     pub struct PusTmSecHeaderWithoutTimestamp {
         pus_version_and_sc_time_ref_status: u8,
-        service: u8,
+        service_type_id: u8,
-        subservice: u8,
+        message_subtype_id: u8,
         msg_counter: U16<NetworkEndian>,
         dest_id: U16<NetworkEndian>,
     }
 
-    pub struct PusTmSecHeader<'slice> {
+    /// PUS TM secondary header with timestamp.
+    pub struct PusTmSecHeader<'time> {
         pub(crate) zc_header: PusTmSecHeaderWithoutTimestamp,
-        pub(crate) timestamp: &'slice [u8],
+        pub(crate) timestamp: &'time [u8],
     }
 
     impl TryFrom<crate::ecss::tm::PusTmSecondaryHeader<'_>> for PusTmSecHeaderWithoutTimestamp {
@@ -125,8 +148,8 @@ pub mod zc {
             Ok(PusTmSecHeaderWithoutTimestamp {
                 pus_version_and_sc_time_ref_status: ((header.pus_version as u8) << 4)
                     | header.sc_time_ref_status.as_u8(),
-                service: header.service,
+                service_type_id: header.service_type_id(),
-                subservice: header.subservice,
+                message_subtype_id: header.message_subtype_id(),
                 msg_counter: U16::from(header.msg_counter),
                 dest_id: U16::from(header.dest_id),
             })
@@ -146,18 +169,27 @@ pub mod zc {
             u4::new(self.pus_version_and_sc_time_ref_status & 0b1111)
         }
 
+        /// Message type ID.
         #[inline]
-        fn service(&self) -> u8 {
+        fn message_type_id(&self) -> MessageTypeId {
-            self.service
+            MessageTypeId {
+                type_id: self.service_type_id,
+                subtype_id: self.message_subtype_id,
+            }
         }
 
         #[inline]
-        fn subservice(&self) -> u8 {
+        fn service_type_id(&self) -> u8 {
-            self.subservice
+            self.service_type_id
         }
 
         #[inline]
-        fn msg_counter(&self) -> u16 {
+        fn message_subtype_id(&self) -> u8 {
+            self.message_subtype_id
+        }
+
+        #[inline]
+        fn msg_type_counter(&self) -> u16 {
             self.msg_counter.get()
         }
 
@@ -168,35 +200,42 @@ pub mod zc {
     }
 }
 
+/// PUS TM secondary header.
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTmSecondaryHeader<'stamp> {
     pus_version: PusVersion,
+    /// Spacecraft time reference status.
     pub sc_time_ref_status: u4,
-    pub service: u8,
+    /// Message type ID.
-    pub subservice: u8,
+    pub message_type_id: MessageTypeId,
+    /// Message counter for the message service type ID.
     pub msg_counter: u16,
+    /// Destination ID.
     pub dest_id: u16,
+    /// Raw timestamp slice.
     pub timestamp: &'stamp [u8],
 }
 
 impl<'stamp> PusTmSecondaryHeader<'stamp> {
+    /// Constructor where only the message type ID and timestamp are specified. The other fields
+    /// are set to default values.
     #[inline]
-    pub fn new_simple(service: u8, subservice: u8, timestamp: &'stamp [u8]) -> Self {
+    pub fn new_simple(message_type_id: MessageTypeId, timestamp: &'stamp [u8]) -> Self {
-        Self::new(service, subservice, 0, 0, timestamp)
+        Self::new(message_type_id, 0, 0, timestamp)
     }
 
     /// Like [Self::new_simple] but without a timestamp.
     #[inline]
-    pub fn new_simple_no_timestamp(service: u8, subservice: u8) -> Self {
+    pub fn new_simple_no_timestamp(message_type_id: MessageTypeId) -> Self {
-        Self::new(service, subservice, 0, 0, &[])
+        Self::new(message_type_id, 0, 0, &[])
     }
 
+    /// Generic constructor.
     #[inline]
     pub fn new(
-        service: u8,
+        message_type_id: MessageTypeId,
-        subservice: u8,
         msg_counter: u16,
         dest_id: u16,
         timestamp: &'stamp [u8],
@@ -204,8 +243,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         PusTmSecondaryHeader {
             pus_version: PusVersion::PusC,
             sc_time_ref_status: u4::new(0),
-            service,
+            message_type_id,
-            subservice,
             msg_counter,
             dest_id,
             timestamp,
@@ -225,17 +263,12 @@ impl GenericPusTmSecondaryHeader for PusTmSecondaryHeader<'_> {
     }
 
     #[inline]
-    fn service(&self) -> u8 {
+    fn message_type_id(&self) -> MessageTypeId {
-        self.service
+        self.message_type_id
     }
 
     #[inline]
-    fn subservice(&self) -> u8 {
+    fn msg_type_counter(&self) -> u16 {
-        self.subservice
-    }
-
-    #[inline]
-    fn msg_counter(&self) -> u16 {
         self.msg_counter
     }
 
@@ -257,9 +290,8 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
         Ok(PusTmSecondaryHeader {
             pus_version: version.unwrap(),
             sc_time_ref_status: sec_header.zc_header.sc_time_ref_status(),
-            service: sec_header.zc_header.service(),
+            message_type_id: sec_header.zc_header.message_type_id(),
-            subservice: sec_header.zc_header.subservice(),
+            msg_counter: sec_header.zc_header.msg_type_counter(),
-            msg_counter: sec_header.zc_header.msg_counter(),
             dest_id: sec_header.zc_header.dest_id(),
             timestamp: sec_header.timestamp,
         })
@@ -283,7 +315,9 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTmCreator<'time, 'src_data> {
+    /// Space packet header.
     pub sp_header: SpHeader,
+    /// Secondary header.
     #[cfg_attr(feature = "serde", serde(borrow))]
     pub sec_header: PusTmSecondaryHeader<'time>,
     source_data: &'src_data [u8],
@@ -326,11 +360,12 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
         pus_tm
     }
 
+    /// Simple constructor which builds the [PusTmSecondaryHeader] internally from the
+    /// provided arguments.
     #[inline]
     pub fn new_simple(
         sp_header: SpHeader,
-        service: u8,
+        message_type_id: MessageTypeId,
-        subservice: u8,
         time_provider: &impl TimeWriter,
         stamp_buf: &'time mut [u8],
         source_data: &'src_data [u8],
@@ -338,10 +373,11 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
     ) -> Result<Self, TimestampError> {
         let stamp_size = time_provider.write_to_bytes(stamp_buf)?;
         let sec_header =
-            PusTmSecondaryHeader::new_simple(service, subservice, &stamp_buf[0..stamp_size]);
+            PusTmSecondaryHeader::new_simple(message_type_id, &stamp_buf[0..stamp_size]);
         Ok(Self::new(sp_header, sec_header, source_data, packet_config))
     }
 
+    /// Constructor for PUS TM packets without source data.
     #[inline]
     pub fn new_no_source_data(
         sp_header: SpHeader,
@@ -351,50 +387,60 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
         Self::new(sp_header, sec_header, &[], packet_config)
     }
 
+    /// Builder API.
     pub fn builder() -> PusTmBuilder<'time, 'src_data> {
         PusTmBuilder::new()
     }
 
+    /// Does the packet have a checksum?
     #[inline]
     pub fn has_checksum(&self) -> bool {
         self.has_checksum
     }
 
+    /// Raw timestamp slice.
     #[inline]
     pub fn timestamp(&self) -> &[u8] {
         self.sec_header.timestamp
     }
 
+    /// Raw source data slice.
     #[inline]
     pub fn source_data(&self) -> &[u8] {
         self.source_data
     }
 
+    /// Servcie type ID.
     #[inline]
-    pub fn service(&self) -> u8 {
+    pub fn service_type_id(&self) -> u8 {
-        self.sec_header.service
+        self.sec_header.service_type_id()
     }
 
+    /// Message subtype ID.
     #[inline]
-    pub fn subservice(&self) -> u8 {
+    pub fn message_subtype_id(&self) -> u8 {
-        self.sec_header.subservice
+        self.sec_header.message_subtype_id()
     }
 
+    /// Application Process Identifier (APID).
     #[inline]
     pub fn apid(&self) -> u11 {
         self.sp_header.packet_id.apid
     }
 
+    /// Set the destination ID.
     #[inline]
     pub fn set_dest_id(&mut self, dest_id: u16) {
         self.sec_header.dest_id = dest_id;
     }
 
+    /// Set the message counter for the service type ID.
     #[inline]
     pub fn set_msg_counter(&mut self, msg_counter: u16) {
         self.sec_header.msg_counter = msg_counter
     }
 
+    /// Set the spacecraft time reference status.
     #[inline]
     pub fn set_sc_time_ref_status(&mut self, sc_time_ref_status: u4) {
         self.sec_header.sc_time_ref_status = sc_time_ref_status;
@@ -567,9 +613,7 @@ impl PusPacket for PusTmCreator<'_, '_> {
 
     delegate!(to self.sec_header {
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
-        #[inline]
-        fn subservice(&self) -> u8;
     });
 
     #[inline]
@@ -590,14 +634,21 @@ impl GenericPusTmSecondaryHeader for PusTmCreator<'_, '_> {
     delegate!(to self.sec_header {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
+        /// Message type ID.
+        fn message_type_id(&self) -> MessageTypeId;
+
+        /// Service type ID.
         #[inline]
-        fn service(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+
+        /// Message subtype ID.
         #[inline]
-        fn subservice(&self) -> u8;
+        fn message_subtype_id(&self) -> u8;
+
         #[inline]
         fn dest_id(&self) -> u16;
         #[inline]
-        fn msg_counter(&self) -> u16;
+        fn msg_type_counter(&self) -> u16;
         #[inline]
         fn sc_time_ref_status(&self) -> u4;
     });
@@ -605,6 +656,7 @@ impl GenericPusTmSecondaryHeader for PusTmCreator<'_, '_> {
 
 impl IsPusTelemetry for PusTmCreator<'_, '_> {}
 
+/// PUS TM bulder API.
 #[derive(Debug)]
 pub struct PusTmBuilder<'time, 'src_data> {
     sp_header: SpHeader,
@@ -620,6 +672,7 @@ impl Default for PusTmBuilder<'_, '_> {
 }
 
 impl PusTmBuilder<'_, '_> {
+    /// Constructor.
     pub fn new() -> Self {
         Self {
             sp_header: SpHeader::new(
@@ -627,18 +680,28 @@ impl PusTmBuilder<'_, '_> {
                 PacketSequenceControl::new(SequenceFlags::Unsegmented, u14::new(0)),
                 0,
             ),
-            sec_header: PusTmSecondaryHeader::new(0, 0, 0, 0, &[]),
+            sec_header: PusTmSecondaryHeader::new(
+                MessageTypeId {
+                    type_id: 0,
+                    subtype_id: 0,
+                },
+                0,
+                0,
+                &[],
+            ),
             source_data: &[],
             has_checksum: true,
         }
     }
 
+    /// Set the application process identifier (APID).
     #[inline]
     pub fn with_apid(mut self, apid: u11) -> Self {
         self.sp_header.packet_id.set_apid(apid);
         self
     }
 
+    /// Set the packet ID.
     #[inline]
     pub fn with_packet_id(mut self, mut packet_id: PacketId) -> Self {
         packet_id.packet_type = PacketType::Tc;
@@ -646,48 +709,63 @@ impl PusTmBuilder<'_, '_> {
         self
     }
 
+    /// Set the packet sequence control.
     #[inline]
     pub fn with_packet_sequence_control(mut self, psc: PacketSequenceControl) -> Self {
         self.sp_header.psc = psc;
         self
     }
 
+    /// Set the sequence count.
     #[inline]
     pub fn with_sequence_count(mut self, seq_count: u14) -> Self {
         self.sp_header.psc.seq_count = seq_count;
         self
     }
 
+    /// Set the message type ID.
     #[inline]
-    pub fn with_service(mut self, service: u8) -> Self {
+    pub fn with_message_type_id(mut self, message_type_id: MessageTypeId) -> Self {
-        self.sec_header.service = service;
+        self.sec_header.message_type_id = message_type_id;
         self
     }
 
+    /// Set the service type ID.
     #[inline]
-    pub fn with_subservice(mut self, service: u8) -> Self {
+    pub fn with_service_type_id(mut self, type_id: u8) -> Self {
-        self.sec_header.subservice = service;
+        self.sec_header.message_type_id.type_id = type_id;
         self
     }
 
+    /// Set the message subtype ID.
+    #[inline]
+    pub fn with_message_subtype_id(mut self, subtype_id: u8) -> Self {
+        self.sec_header.message_type_id.subtype_id = subtype_id;
+        self
+    }
+
+    /// Set the destination ID.
     #[inline]
     pub fn with_dest_id(mut self, dest_id: u16) -> Self {
         self.sec_header.dest_id = dest_id;
         self
     }
 
+    /// Set the message counter for the service type ID.
     #[inline]
     pub fn with_msg_counter(mut self, msg_counter: u16) -> Self {
         self.sec_header.msg_counter = msg_counter;
         self
     }
 
+    /// Set the spacecraft time reference status.
     #[inline]
     pub fn with_sc_time_ref_status(mut self, sc_time_ref_status: u4) -> Self {
         self.sec_header.sc_time_ref_status = sc_time_ref_status;
         self
     }
 
+    /// Enable or disable checksum generation.
     #[inline]
     pub fn with_checksum(mut self, has_checksum: bool) -> Self {
         self.has_checksum = has_checksum;
@@ -696,6 +774,7 @@ impl PusTmBuilder<'_, '_> {
 }
 
 impl<'src_data> PusTmBuilder<'_, 'src_data> {
+    /// Set the source data.
     #[inline]
     pub fn with_source_data(mut self, source_data: &'src_data [u8]) -> Self {
         self.source_data = source_data;
@@ -704,6 +783,7 @@ impl<'src_data> PusTmBuilder<'_, 'src_data> {
 }
 
 impl<'time> PusTmBuilder<'time, '_> {
+    /// Set the timestamp.
     #[inline]
     pub fn with_timestamp(mut self, timestamp: &'time [u8]) -> Self {
         self.sec_header.timestamp = timestamp;
@@ -712,6 +792,7 @@ impl<'time> PusTmBuilder<'time, '_> {
 }
 
 impl<'time, 'src_data> PusTmBuilder<'time, 'src_data> {
+    /// Constructor.
     pub fn build(self) -> PusTmCreator<'time, 'src_data> {
         PusTmCreator::new(
             self.sp_header,
@@ -812,6 +893,7 @@ impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
         })
     }
 
+    /// Length of the full packet written to the buffer.
     #[inline]
     pub const fn len_written(&self) -> usize {
         self.full_len
@@ -837,6 +919,7 @@ impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
         }
     }
 
+    /// Length of the source data.
     #[inline]
     pub fn source_data_len(&self) -> usize {
         let mut len = self.full_len - self.source_data_offset;
@@ -886,11 +969,16 @@ impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
     }
 }
 
+/// Configuration options for the [PusTmReader].
+///
+/// This includes managed parameters which can not be deduced from the raw byte slice itself.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct ReaderConfig {
+    /// Expected timestamp length.
     pub timestamp_len: usize,
+    /// Does the packet have a checksum?
     pub has_checksum: bool,
 }
 
@@ -910,7 +998,9 @@ pub struct ReaderConfig {
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTmReader<'raw_data> {
+    /// Space packet header.
     pub sp_header: SpHeader,
+    /// PUS TM secondary header.
     pub sec_header: PusTmSecondaryHeader<'raw_data>,
     #[cfg_attr(feature = "serde", serde(skip))]
     raw_data: &'raw_data [u8],
@@ -968,6 +1058,7 @@ impl<'raw_data> PusTmReader<'raw_data> {
         )
     }
 
+    /// Constructor which does not perform checksum verification.
     pub fn new_no_checksum_verification(
         slice: &'raw_data [u8],
         reader_config: ReaderConfig,
@@ -1017,7 +1108,7 @@ impl<'raw_data> PusTmReader<'raw_data> {
         }
         Ok(Self {
             sp_header,
-            sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper).unwrap(),
+            sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper)?,
             raw_data,
             source_data: user_data_from_raw(
                 current_idx,
@@ -1029,41 +1120,49 @@ impl<'raw_data> PusTmReader<'raw_data> {
         })
     }
 
+    /// Length of the full packed PUS TM packet.
     #[inline]
     pub fn len_packed(&self) -> usize {
         self.sp_header.packet_len()
     }
 
+    /// Source data slice.
     #[inline]
     pub fn source_data(&self) -> &[u8] {
         self.user_data()
     }
 
+    /// Service type ID.
     #[inline]
-    pub fn service(&self) -> u8 {
+    pub fn service_type_id(&self) -> u8 {
-        self.sec_header.service
+        self.sec_header.service_type_id()
     }
 
+    /// Message subtype ID.
     #[inline]
-    pub fn subservice(&self) -> u8 {
+    pub fn message_subtype_id(&self) -> u8 {
-        self.sec_header.subservice
+        self.sec_header.message_subtype_id()
     }
 
+    /// Full packet length.
     #[inline]
     pub fn packet_len(&self) -> usize {
         self.sp_header.packet_len()
     }
 
+    /// Application Process Identifier (APID).
     #[inline]
     pub fn apid(&self) -> u11 {
         self.sp_header.packet_id.apid
     }
 
+    /// Raw timestamp slice.
     #[inline]
     pub fn timestamp(&self) -> &[u8] {
         self.sec_header.timestamp
     }
 
+    /// Does the packet have a checksum?
     #[inline]
     pub fn checksum(&self) -> Option<u16> {
         self.checksum
@@ -1102,10 +1201,15 @@ impl PusPacket for PusTmReader<'_> {
     delegate!(to self.sec_header {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
+
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
+
         #[inline]
-        fn subservice(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+
+        #[inline]
+        fn message_subtype_id(&self) -> u8;
     });
 
     #[inline]
@@ -1129,13 +1233,15 @@ impl GenericPusTmSecondaryHeader for PusTmReader<'_> {
         #[inline]
         fn pus_version(&self) -> Result<PusVersion, u4>;
         #[inline]
-        fn service(&self) -> u8;
+        fn message_type_id(&self) -> MessageTypeId;
         #[inline]
-        fn subservice(&self) -> u8;
+        fn service_type_id(&self) -> u8;
+        #[inline]
+        fn message_subtype_id(&self) -> u8;
         #[inline]
         fn dest_id(&self) -> u16;
         #[inline]
-        fn msg_counter(&self) -> u16;
+        fn msg_type_counter(&self) -> u16;
         #[inline]
         fn sc_time_ref_status(&self) -> u4;
     });
@@ -1202,6 +1308,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
         Some(writer)
     }
 
+    /// Set the application process identifier (APID).
     #[inline]
     pub fn set_apid(&mut self, apid: u11) {
         // Clear APID part of the raw packet ID
@@ -1241,6 +1348,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
         .unwrap()
     }
 
+    /// Set the sequence count in the CCSDS packet header.
     #[inline]
     pub fn set_seq_count(&mut self, seq_count: u14) {
         let new_psc = (u16::from_be_bytes(self.raw_tm[2..4].try_into().unwrap()) & 0xC000)
@@ -1257,6 +1365,24 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
             self.raw_tm[slice_len - 2..].copy_from_slice(&crc16.to_be_bytes());
         }
     }
+
+    #[inline]
+    fn service_type_id(&self) -> u8 {
+        self.raw_tm[7]
+    }
+
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.raw_tm[8]
+    }
+
+    #[inline]
+    fn message_type_id(&self) -> MessageTypeId {
+        MessageTypeId {
+            type_id: self.service_type_id(),
+            subtype_id: self.message_subtype_id(),
+        }
+    }
 }
 
 impl CcsdsPacket for PusTmZeroCopyWriter<'_> {
@@ -1287,19 +1413,24 @@ impl PusPacket for PusTmZeroCopyWriter<'_> {
         self.sec_header_without_timestamp().pus_version()
     }
 
-    #[inline]
-    fn service(&self) -> u8 {
-        self.raw_tm[7]
-    }
-
     #[inline]
     fn has_checksum(&self) -> bool {
         self.has_checksum
     }
 
     #[inline]
-    fn subservice(&self) -> u8 {
+    fn service_type_id(&self) -> u8 {
-        self.raw_tm[8]
+        self.service_type_id()
+    }
+
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.message_subtype_id()
+    }
+
+    #[inline]
+    fn message_type_id(&self) -> MessageTypeId {
+        self.message_type_id()
     }
 
     #[inline]
@@ -1334,20 +1465,25 @@ impl GenericPusTmSecondaryHeader for PusTmZeroCopyWriter<'_> {
             #[inline]
             fn sc_time_ref_status(&self) -> u4;
             #[inline]
-            fn msg_counter(&self) -> u16;
+            fn msg_type_counter(&self) -> u16;
             #[inline]
             fn dest_id(&self) -> u16;
         }
     }
 
     #[inline]
-    fn service(&self) -> u8 {
+    fn service_type_id(&self) -> u8 {
-        PusPacket::service(self)
+        self.service_type_id()
     }
 
     #[inline]
-    fn subservice(&self) -> u8 {
+    fn message_subtype_id(&self) -> u8 {
-        PusPacket::subservice(self)
+        self.message_subtype_id()
+    }
+
+    #[inline]
+    fn message_type_id(&self) -> MessageTypeId {
+        self.message_type_id()
     }
 }
 
@@ -1367,7 +1503,7 @@ mod tests {
 
     fn base_ping_reply_full_ctor<'a, 'b>(timestamp: &'a [u8]) -> PusTmCreator<'a, 'b> {
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
+        let tm_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), timestamp);
         PusTmCreator::new_no_source_data(sph, tm_header, CreatorConfig::default())
     }
 
@@ -1379,23 +1515,23 @@ mod tests {
             return PusTmCreator::builder()
                 .with_apid(u11::new(0x123))
                 .with_sequence_count(u14::new(0x234))
-                .with_service(17)
+                .with_service_type_id(17)
-                .with_subservice(2)
+                .with_message_subtype_id(2)
                 .with_timestamp(timestamp)
                 .build();
         }
         PusTmBuilder::new()
             .with_apid(u11::new(0x123))
             .with_sequence_count(u14::new(0x234))
-            .with_service(17)
+            .with_service_type_id(17)
-            .with_subservice(2)
+            .with_message_subtype_id(2)
             .with_timestamp(timestamp)
             .build()
     }
 
     fn base_ping_reply_full_ctor_no_checksum<'a, 'b>(timestamp: &'a [u8]) -> PusTmCreator<'a, 'b> {
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
+        let tm_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), timestamp);
         PusTmCreator::new_no_source_data(
             sph,
             tm_header,
@@ -1407,13 +1543,13 @@ mod tests {
     }
     fn ping_reply_with_data<'a, 'b>(timestamp: &'a [u8]) -> PusTmCreator<'a, 'b> {
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
+        let tm_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), timestamp);
         PusTmCreator::new(sph, tm_header, DUMMY_DATA, CreatorConfig::default())
     }
 
     fn base_hk_reply<'a, 'b>(timestamp: &'a [u8], src_data: &'b [u8]) -> PusTmCreator<'a, 'b> {
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, timestamp);
+        let tc_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(3, 5), timestamp);
         PusTmCreator::new(sph, tc_header, src_data, CreatorConfig::default())
     }
 
@@ -1422,7 +1558,7 @@ mod tests {
         src_data: &'b [u8],
     ) -> PusTmCreator<'a, 'b> {
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, timestamp);
+        let tc_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(3, 5), timestamp);
         PusTmCreator::new(
             sph,
             tc_header,
@@ -1459,8 +1595,7 @@ mod tests {
         let mut stamp_buf: [u8; 8] = [0; 8];
         let pus_tm = PusTmCreator::new_simple(
             sph,
-            17,
+            MessageTypeId::new(17, 2),
-            2,
             &time_provider,
             &mut stamp_buf,
             &[],
@@ -1486,7 +1621,7 @@ mod tests {
     fn test_serialization_no_source_data_alt_ctor() {
         let timestamp = dummy_timestamp();
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
+        let tm_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), timestamp);
         let mut buf: [u8; 32] = [0; 32];
         let mut pus_tm =
             PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tm_header, 0, true).unwrap();
@@ -1502,7 +1637,7 @@ mod tests {
     fn test_serialization_no_source_data_alt_ctor_no_checksum_verification() {
         let timestamp = dummy_timestamp();
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
+        let tm_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), timestamp);
         let mut buf: [u8; 32] = [0; 32];
         let mut pus_tm =
             PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tm_header, 0, true).unwrap();
@@ -1520,7 +1655,7 @@ mod tests {
     fn test_serialization_no_source_data_alt_ctor_no_checksum() {
         let timestamp = dummy_timestamp();
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
+        let tm_header = PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), timestamp);
         let mut buf: [u8; 32] = [0; 32];
         let mut pus_tm =
             PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tm_header, 0, false).unwrap();
@@ -1596,7 +1731,8 @@ mod tests {
         let src_data = &[1, 2, 3];
         let mut buf: [u8; 32] = [0; 32];
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, dummy_timestamp());
+        let tc_header =
+            PusTmSecondaryHeader::new_simple(MessageTypeId::new(3, 5), dummy_timestamp());
         let mut hk_reply_unwritten =
             PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tc_header, 3, true).unwrap();
         assert_eq!(hk_reply_unwritten.source_data_len(), 3);
@@ -1616,7 +1752,8 @@ mod tests {
         let src_data = &[1, 2, 3];
         let mut buf: [u8; 32] = [0; 32];
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, dummy_timestamp());
+        let tc_header =
+            PusTmSecondaryHeader::new_simple(MessageTypeId::new(3, 5), dummy_timestamp());
         let mut hk_reply_unwritten =
             PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tc_header, 3, true).unwrap();
         assert_eq!(hk_reply_unwritten.source_data_len(), 3);
@@ -1640,7 +1777,7 @@ mod tests {
         pus_tm.set_msg_counter(0x1f1f);
         assert_eq!(pus_tm.sc_time_ref_status().value(), 0b1010);
         assert_eq!(pus_tm.dest_id(), 0x7fff);
-        assert_eq!(pus_tm.msg_counter(), 0x1f1f);
+        assert_eq!(pus_tm.msg_type_counter(), 0x1f1f);
         pus_tm.set_apid(u11::new(0x7ff));
         assert_eq!(pus_tm.apid().value(), 0x7ff);
     }
@@ -1772,7 +1909,8 @@ mod tests {
     #[test]
     fn test_manual_field_update() {
         let sph = SpHeader::new_for_unseg_tm(u11::new(0x123), u14::new(0x234), 0);
-        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, dummy_timestamp());
+        let tc_header =
+            PusTmSecondaryHeader::new_simple(MessageTypeId::new(17, 2), dummy_timestamp());
         let mut tm = PusTmCreator::new_no_source_data(
             sph,
             tc_header,
@@ -1928,10 +2066,10 @@ mod tests {
         exp_full_len: usize,
     ) {
         assert!(tm.is_tm());
-        assert_eq!(PusPacket::service(tm), 17);
+        assert_eq!(PusPacket::service_type_id(tm), 17);
-        assert_eq!(GenericPusTmSecondaryHeader::service(tm), 17);
+        assert_eq!(GenericPusTmSecondaryHeader::service_type_id(tm), 17);
-        assert_eq!(PusPacket::subservice(tm), 2);
+        assert_eq!(PusPacket::message_subtype_id(tm), 2);
-        assert_eq!(GenericPusTmSecondaryHeader::subservice(tm), 2);
+        assert_eq!(GenericPusTmSecondaryHeader::message_subtype_id(tm), 2);
         assert!(tm.sec_header_flag());
         if has_user_data {
             assert!(!tm.user_data().is_empty());
@@ -1946,7 +2084,7 @@ mod tests {
         );
         assert_eq!(tm.data_len(), exp_full_len as u16 - 7);
         assert_eq!(tm.dest_id(), 0x0000);
-        assert_eq!(tm.msg_counter(), 0x0000);
+        assert_eq!(tm.msg_type_counter(), 0x0000);
         assert_eq!(tm.sc_time_ref_status().value(), 0b0000);
     }
 
@@ -1984,7 +2122,7 @@ mod tests {
         // This performs all necessary checks, including the CRC check.
         let tm_read_back = PusTmReader::new(&buf, 7).expect("Re-creating PUS TM failed");
         assert_eq!(tm_read_back.packet_len(), tm_size);
-        assert_eq!(tm_read_back.msg_counter(), 100);
+        assert_eq!(tm_read_back.msg_type_counter(), 100);
         assert_eq!(tm_read_back.dest_id(), 55);
         assert_eq!(tm_read_back.seq_count(), MAX_SEQ_COUNT);
         assert_eq!(tm_read_back.apid(), MAX_APID);
@@ -2003,8 +2141,8 @@ mod tests {
         writer.set_msg_count(100);
         writer.set_seq_count(MAX_SEQ_COUNT);
         writer.set_apid(MAX_APID);
-        assert_eq!(PusPacket::service(&writer), 17);
+        assert_eq!(PusPacket::service_type_id(&writer), 17);
-        assert_eq!(PusPacket::subservice(&writer), 2);
+        assert_eq!(PusPacket::message_subtype_id(&writer), 2);
         assert_eq!(writer.apid(), MAX_APID);
         assert_eq!(writer.seq_count(), MAX_SEQ_COUNT);
     }
@@ -2023,12 +2161,15 @@ mod tests {
         writer.set_msg_count(100);
         writer.set_seq_count(MAX_SEQ_COUNT);
         writer.set_apid(MAX_APID);
-        assert_eq!(PusPacket::service(&writer), 17);
+        assert_eq!(PusPacket::service_type_id(&writer), 17);
-        assert_eq!(PusPacket::subservice(&writer), 2);
+        assert_eq!(PusPacket::message_subtype_id(&writer), 2);
         assert_eq!(writer.dest_id(), 55);
-        assert_eq!(writer.msg_counter(), 100);
+        assert_eq!(writer.msg_type_counter(), 100);
         assert_eq!(writer.sec_header_without_timestamp().dest_id(), 55);
-        assert_eq!(writer.sec_header_without_timestamp().msg_counter(), 100);
+        assert_eq!(
+            writer.sec_header_without_timestamp().msg_type_counter(),
+            100
+        );
         assert_eq!(writer.user_data(), DUMMY_DATA);
         // Need to check crc16 before finish, because finish will update the CRC.
         let crc16 = writer.checksum();
@@ -2039,7 +2180,7 @@ mod tests {
 
     #[test]
     fn test_sec_header_without_stamp() {
-        let sec_header = PusTmSecondaryHeader::new_simple_no_timestamp(17, 1);
+        let sec_header = PusTmSecondaryHeader::new_simple_no_timestamp(MessageTypeId::new(17, 1));
         assert_eq!(sec_header.timestamp, &[]);
     }
 
@@ -2105,8 +2246,7 @@ mod tests {
         let mut stamp_buf: [u8; 8] = [0; 8];
         let pus_tm = PusTmCreator::new_simple(
             sph,
-            17,
+            MessageTypeId::new(17, 2),
-            2,
             &time_provider,
             &mut stamp_buf,
             &[],
@@ -2127,8 +2267,7 @@ mod tests {
         let mut stamp_buf: [u8; 8] = [0; 8];
         let pus_tm = PusTmCreator::new_simple(
             sph,
-            17,
+            MessageTypeId::new(17, 2),
-            2,
             &time_provider,
             &mut stamp_buf,
             &[],
@@ -2166,8 +2305,8 @@ mod tests {
                 SequenceFlags::Unsegmented,
                 u14::new(0x34),
             ))
-            .with_service(17)
+            .with_service_type_id(17)
-            .with_subservice(2)
+            .with_message_subtype_id(2)
             .with_dest_id(0x2f2f)
             .with_checksum(false)
             .build();
@@ -2175,7 +2314,7 @@ mod tests {
         assert_eq!(tm.sequence_flags(), SequenceFlags::Unsegmented);
         assert_eq!(tm.apid().value(), 0x02);
         assert_eq!(tm.packet_type(), PacketType::Tm);
-        assert_eq!(tm.service(), 17);
+        assert_eq!(tm.service_type_id(), 17);
-        assert_eq!(tm.subservice(), 2);
+        assert_eq!(tm.message_subtype_id(), 2);
     }
 }

src/ecss/tm_pus_a.rs

@@ -27,8 +27,8 @@
 //!     true
 //! );
 //! println!("{:?}", ping_tm);
-//! assert_eq!(ping_tm.service(), 17);
+//! assert_eq!(ping_tm.service_type_id(), 17);
-//! assert_eq!(ping_tm.subservice(), 2);
+//! assert_eq!(ping_tm.message_subtype_id(), 2);
 //! assert_eq!(ping_tm.apid().value(), 0x02);
 //!
 //! // Serialize TM into a raw buffer
@@ -42,16 +42,17 @@
 //! // Deserialize from the raw byte representation
 //! let ping_tm_reader = PusTmReader::new(&test_buf, &SecondaryHeaderParameters::new_minimal(7)).expect("deserialization failed");
 //! assert_eq!(written_size, ping_tm_reader.packet_len());
-//! assert_eq!(ping_tm_reader.service(), 17);
+//! assert_eq!(ping_tm_reader.service_type_id(), 17);
-//! assert_eq!(ping_tm_reader.subservice(), 2);
+//! assert_eq!(ping_tm_reader.message_subtype_id(), 2);
 //! assert_eq!(ping_tm_reader.apid().value(), 0x02);
 //! assert_eq!(ping_tm_reader.timestamp(), &time_buf);
 //! ```
 use crate::crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE};
+use crate::ecss::tm::IsPusTelemetry;
 use crate::ecss::{
     calc_pus_crc16, crc_from_raw_data, sp_header_impls, user_data_from_raw,
-    verify_crc16_ccitt_false_from_raw_to_pus_error, CrcType, PusError, PusPacket, PusVersion,
+    verify_crc16_ccitt_false_from_raw_to_pus_error, CrcType, MessageTypeId, PusError, PusPacket,
-    WritablePusPacket,
+    PusVersion, WritablePusPacket,
 };
 use crate::util::{UnsignedByteField, UnsignedEnum};
 use crate::{
@@ -73,55 +74,78 @@ use crate::time::{TimeWriter, TimestampError};
 
 use super::verify_crc16_ccitt_false_from_raw_to_pus_error_no_table;
 
-pub trait IsPusTelemetry {}
-
 /// Length without timestamp
 pub const PUS_TM_MIN_SEC_HEADER_LEN: usize = 3;
+/// Minimal length of a PUS TM packet without source data.
 pub const PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA: usize =
     CCSDS_HEADER_LEN + PUS_TM_MIN_SEC_HEADER_LEN + size_of::<CrcType>();
 
+/// Generic properties of a PUS-A PUS TM secondary header.
 pub trait GenericPusTmSecondaryHeader {
+    /// PUS version field.
     fn pus_version(&self) -> PusVersion;
+    /// Service field.
     fn service(&self) -> u8;
+    /// Subservice field.
     fn subservice(&self) -> u8;
+    /// Message counter field for the service ID.
     fn msg_counter(&self) -> Option<u8>;
+    /// Destination ID.
     fn dest_id(&self) -> Option<UnsignedByteField>;
+    /// Number of spare bytes.
     fn spare_bytes(&self) -> usize;
 }
 
+/// Managed parameters for the secondary header which can not be deduced from the packet itself.
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 pub struct SecondaryHeaderParameters {
+    /// Timestamp length in bytes.
     pub timestamp_len: usize,
+    /// Does the packet have a message counter?
     pub has_msg_counter: bool,
-    pub dest_id_len: Option<usize>,
+    /// Present and length of the destination ID.
+    pub opt_dest_id_len: Option<usize>,
+    /// Number of spare bytes.
     pub spare_bytes: usize,
 }
 
 impl SecondaryHeaderParameters {
+    /// Minimal constructor.
     pub const fn new_minimal(timestamp_len: usize) -> Self {
         Self {
             timestamp_len,
             has_msg_counter: false,
-            dest_id_len: None,
+            opt_dest_id_len: None,
             spare_bytes: 0,
         }
     }
 }
 
+/// PUS TM secondary header.
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTmSecondaryHeader<'stamp> {
     pus_version: PusVersion,
+    /// Service field.
     pub service: u8,
+    /// Subservice field.
     pub subservice: u8,
+    /// Service message counter.
     pub msg_counter: Option<u8>,
+    /// Destination ID field.
     pub dest_id: Option<UnsignedByteField>,
+    /// Timestamp slice.
     pub timestamp: &'stamp [u8],
+    /// Number of spare bytes to add after the timestamp.
     pub spare_bytes: usize,
 }
 
 impl<'stamp> PusTmSecondaryHeader<'stamp> {
+    /// Simple constructor.
+    ///
+    /// Allows setting the service, subservice and timestamp and sets default values for the
+    /// other fields.
     #[inline]
     pub fn new_simple(service: u8, subservice: u8, timestamp: &'stamp [u8]) -> Self {
         Self::new(service, subservice, None, None, timestamp, 0)
@@ -133,6 +157,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         Self::new(service, subservice, None, None, &[], 0)
     }
 
+    /// Generic constructor.
     #[inline]
     pub fn new(
         service: u8,
@@ -153,6 +178,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         }
     }
 
+    /// Construct the secondary header from a raw byte slice.
     pub fn from_bytes(
         buf: &'stamp [u8],
         params: &SecondaryHeaderParameters,
@@ -180,7 +206,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
             current_idx += 1;
         }
         let mut dest_id = None;
-        if let Some(dest_id_len) = params.dest_id_len {
+        if let Some(dest_id_len) = params.opt_dest_id_len {
             dest_id = Some(
                 UnsignedByteField::new_from_be_bytes(
                     dest_id_len,
@@ -201,6 +227,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         })
     }
 
+    /// Write the PUS TM secondary header to a provided buffer.
     pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         let written_len = self.written_len();
         if buf.len() < written_len {
@@ -229,6 +256,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         Ok(written_len)
     }
 
+    /// Convert the PUS TM packet secondary header to a [alloc::vec::Vec].
     #[cfg(feature = "alloc")]
     pub fn to_vec(&self) -> Vec<u8> {
         let mut vec = alloc::vec![0; self.written_len()];
@@ -236,6 +264,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         vec
     }
 
+    /// Length of the secondary header when written to bytes.
     pub fn written_len(&self) -> usize {
         let mut len = PUS_TM_MIN_SEC_HEADER_LEN + self.timestamp.len() + self.spare_bytes;
         if let Some(dest_id) = self.dest_id {
@@ -247,9 +276,10 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         len
     }
 
+    /// Length for the provided packet parameters.
     pub fn len_for_params(params: &SecondaryHeaderParameters) -> usize {
         let mut len = PUS_TM_MIN_SEC_HEADER_LEN + params.timestamp_len + params.spare_bytes;
-        if let Some(dest_id) = params.dest_id_len {
+        if let Some(dest_id) = params.opt_dest_id_len {
             len += dest_id;
         }
         if params.has_msg_counter {
@@ -308,7 +338,9 @@ impl GenericPusTmSecondaryHeader for PusTmSecondaryHeader<'_> {
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTmCreator<'time, 'src_data> {
+    /// Space packet header.
     pub sp_header: SpHeader,
+    /// PUS TM secondary header.
     #[cfg_attr(feature = "serde", serde(borrow))]
     pub sec_header: PusTmSecondaryHeader<'time>,
     source_data: &'src_data [u8],
@@ -351,6 +383,8 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
         pus_tm
     }
 
+    /// Simple constructor which builds the [PusTmSecondaryHeader] internally from the
+    /// provided arguments.
     #[inline]
     pub fn new_simple(
         sp_header: SpHeader,
@@ -367,6 +401,7 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
         Ok(Self::new(sp_header, sec_header, source_data, set_ccsds_len))
     }
 
+    /// Constructor for PUS TM packets without source data.
     #[inline]
     pub fn new_no_source_data(
         sp_header: SpHeader,
@@ -376,21 +411,25 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
         Self::new(sp_header, sec_header, &[], set_ccsds_len)
     }
 
+    /// Raw timestamp slice.
     #[inline]
     pub fn timestamp(&self) -> &[u8] {
         self.sec_header.timestamp
     }
 
+    /// Raw source data slice.
     #[inline]
     pub fn source_data(&self) -> &[u8] {
         self.source_data
     }
 
+    /// Set the destination ID.
     #[inline]
     pub fn set_dest_id(&mut self, dest_id: Option<UnsignedByteField>) {
         self.sec_header.dest_id = dest_id;
     }
 
+    /// Set the message counter for the current service ID.
     #[inline]
     pub fn set_msg_counter(&mut self, msg_counter: Option<u8>) {
         self.sec_header.msg_counter = msg_counter
@@ -559,12 +598,22 @@ impl PusPacket for PusTmCreator<'_, '_> {
         Ok(self.sec_header.pus_version)
     }
 
-    delegate!(to self.sec_header {
+    #[inline]
-        #[inline]
+    fn message_type_id(&self) -> super::MessageTypeId {
-        fn service(&self) -> u8;
+        super::MessageTypeId {
-        #[inline]
+            type_id: self.sec_header.service,
-        fn subservice(&self) -> u8;
+            subtype_id: self.sec_header.subservice,
-    });
+        }
+    }
+
+    #[inline]
+    fn service_type_id(&self) -> u8 {
+        self.sec_header.service
+    }
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.sec_header.subservice
+    }
 
     #[inline]
     fn user_data(&self) -> &[u8] {
@@ -665,6 +714,7 @@ impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
         })
     }
 
+    /// Length of the full packet when written to bytes.
     #[inline]
     pub const fn len_written(&self) -> usize {
         self.full_len
@@ -682,6 +732,7 @@ impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
         &self.buf[self.source_data_offset..self.full_len - 2]
     }
 
+    /// Source data length.
     #[inline]
     pub fn source_data_len(&self) -> usize {
         self.full_len - 2 - self.source_data_offset
@@ -735,7 +786,9 @@ impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct PusTmReader<'raw_data> {
+    /// Space packet header.
     pub sp_header: SpHeader,
+    /// PUS TM secondary header.
     pub sec_header: PusTmSecondaryHeader<'raw_data>,
     #[cfg_attr(feature = "serde", serde(skip))]
     raw_data: &'raw_data [u8],
@@ -769,6 +822,7 @@ impl<'raw_data> PusTmReader<'raw_data> {
         Ok(tc)
     }
 
+    /// New constructor which does not check the CRC16.
     pub fn new_no_crc_check(
         slice: &'raw_data [u8],
         sec_header_params: &SecondaryHeaderParameters,
@@ -812,21 +866,25 @@ impl<'raw_data> PusTmReader<'raw_data> {
         })
     }
 
+    /// Length of the full packet as packed in the raw data.
     #[inline]
     pub fn len_packed(&self) -> usize {
         self.sp_header.packet_len()
     }
 
+    /// Raw source data slice.
     #[inline]
     pub fn source_data(&self) -> &[u8] {
         self.user_data()
     }
 
+    /// Raw timestamp slice.
     #[inline]
     pub fn timestamp(&self) -> &[u8] {
         self.sec_header.timestamp
     }
 
+    /// CRC16 checksum of the packet.
     #[inline]
     pub fn crc16(&self) -> u16 {
         self.crc16
@@ -867,12 +925,23 @@ impl PusPacket for PusTmReader<'_> {
         Ok(self.sec_header.pus_version)
     }
 
-    delegate!(to self.sec_header {
+    #[inline]
-        #[inline]
+    fn message_type_id(&self) -> super::MessageTypeId {
-        fn service(&self) -> u8;
+        MessageTypeId {
-        #[inline]
+            type_id: self.sec_header.service,
-        fn subservice(&self) -> u8;
+            subtype_id: self.sec_header.subservice,
-    });
+        }
+    }
+
+    #[inline]
+    fn service_type_id(&self) -> u8 {
+        self.sec_header.service
+    }
+
+    #[inline]
+    fn message_subtype_id(&self) -> u8 {
+        self.sec_header.subservice
+    }
 
     #[inline]
     fn user_data(&self) -> &[u8] {
@@ -920,16 +989,21 @@ impl PartialEq<PusTmReader<'_>> for PusTmCreator<'_, '_> {
     }
 }
 
+/// Secondary header field not present error.
 #[derive(Debug, thiserror::Error)]
 #[error("this field is not present in the secondary header")]
 pub struct SecondaryHeaderFieldNotPresentError;
 
+/// Destination ID operation error.
 #[derive(Debug, thiserror::Error)]
 pub enum DestIdOperationError {
+    /// Field is not present in the secondary header.
     #[error("this field is not present in the secondary header")]
     FieldNotPresent(#[from] SecondaryHeaderFieldNotPresentError),
+    /// Invalid field length.
     #[error("invalid byte field length")]
     InvalidFieldLen,
+    /// Bzyte conversion error.
     #[error("byte conversion error")]
     ByteConversionError(#[from] ByteConversionError),
 }
@@ -987,15 +1061,16 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
         self.raw_tm[0..2].copy_from_slice(&updated_apid.to_be_bytes());
     }
 
+    /// Destination ID field if present.
     pub fn dest_id(&self) -> Result<Option<UnsignedByteField>, ByteConversionError> {
-        if self.sec_header_params.dest_id_len.is_none() {
+        if self.sec_header_params.opt_dest_id_len.is_none() {
             return Ok(None);
         }
         let mut base_idx = 10;
         if self.sec_header_params.has_msg_counter {
             base_idx += 1;
         }
-        let dest_id_len = self.sec_header_params.dest_id_len.unwrap();
+        let dest_id_len = self.sec_header_params.opt_dest_id_len.unwrap();
         if self.raw_tm.len() < base_idx + dest_id_len {
             return Err(ByteConversionError::FromSliceTooSmall {
                 found: self.raw_tm.len(),
@@ -1011,6 +1086,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
         ))
     }
 
+    /// Message counter if present.
     pub fn msg_counter(&self) -> Option<u8> {
         if !self.sec_header_params.has_msg_counter {
             return None;
@@ -1040,10 +1116,10 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
         &mut self,
         dest_id: UnsignedByteField,
     ) -> Result<(), DestIdOperationError> {
-        if self.sec_header_params.dest_id_len.is_none() {
+        if self.sec_header_params.opt_dest_id_len.is_none() {
             return Err(SecondaryHeaderFieldNotPresentError.into());
         }
-        let dest_id_len = self.sec_header_params.dest_id_len.unwrap();
+        let dest_id_len = self.sec_header_params.opt_dest_id_len.unwrap();
         if dest_id.size() != dest_id_len {
             return Err(DestIdOperationError::InvalidFieldLen);
         }
@@ -1072,6 +1148,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
         crate::zc::SpHeader::read_from_bytes(&self.raw_tm[0..CCSDS_HEADER_LEN]).unwrap()
     }
 
+    /// Set the sequence count.
     #[inline]
     pub fn set_seq_count(&mut self, seq_count: u14) {
         let new_psc = (u16::from_be_bytes(self.raw_tm[2..4].try_into().unwrap()) & 0xC000)
@@ -1117,12 +1194,20 @@ impl PusPacket for PusTmZeroCopyWriter<'_> {
     }
 
     #[inline]
-    fn service(&self) -> u8 {
+    fn message_type_id(&self) -> super::MessageTypeId {
+        MessageTypeId {
+            type_id: self.service_type_id(),
+            subtype_id: self.message_subtype_id(),
+        }
+    }
+
+    #[inline]
+    fn service_type_id(&self) -> u8 {
         self.raw_tm[7]
     }
 
     #[inline]
-    fn subservice(&self) -> u8 {
+    fn message_subtype_id(&self) -> u8 {
         self.raw_tm[8]
     }
 
@@ -1494,7 +1579,7 @@ mod tests {
             &SecondaryHeaderParameters {
                 timestamp_len: 7,
                 has_msg_counter: msg_counter.is_some(),
-                dest_id_len: dest_id.as_ref().map(|id| id.size()),
+                opt_dest_id_len: dest_id.as_ref().map(|id| id.size()),
                 spare_bytes: 0,
             },
         )
@@ -1774,9 +1859,9 @@ mod tests {
         msg_counter: Option<u8>,
     ) {
         assert!(tm.is_tm());
-        assert_eq!(PusPacket::service(tm), 17);
+        assert_eq!(PusPacket::service_type_id(tm), 17);
         assert_eq!(GenericPusTmSecondaryHeader::service(tm), 17);
-        assert_eq!(PusPacket::subservice(tm), 2);
+        assert_eq!(PusPacket::message_subtype_id(tm), 2);
         assert_eq!(GenericPusTmSecondaryHeader::subservice(tm), 2);
         assert!(tm.sec_header_flag());
         if has_user_data {
@@ -1849,7 +1934,7 @@ mod tests {
             &SecondaryHeaderParameters {
                 timestamp_len: dummy_timestamp().len(),
                 has_msg_counter: false,
-                dest_id_len: Some(2),
+                opt_dest_id_len: Some(2),
                 spare_bytes: 0,
             },
         )
@@ -1859,8 +1944,8 @@ mod tests {
         writer
             .set_destination_id(UnsignedByteFieldU16::new(0xf1f1).into())
             .unwrap();
-        assert_eq!(PusPacket::service(&writer), 17);
+        assert_eq!(PusPacket::service_type_id(&writer), 17);
-        assert_eq!(PusPacket::subservice(&writer), 2);
+        assert_eq!(PusPacket::message_subtype_id(&writer), 2);
         assert_eq!(
             writer.dest_id().unwrap().unwrap(),
             UnsignedByteFieldU16::new(0xf1f1).into()
@@ -1881,8 +1966,8 @@ mod tests {
             .expect("Creating zero copy writer failed");
         writer.set_seq_count(MAX_SEQ_COUNT);
         writer.set_apid(MAX_APID);
-        assert_eq!(PusPacket::service(&writer), 17);
+        assert_eq!(PusPacket::service_type_id(&writer), 17);
-        assert_eq!(PusPacket::subservice(&writer), 2);
+        assert_eq!(PusPacket::message_subtype_id(&writer), 2);
         assert!(writer.dest_id().unwrap().is_none());
         assert!(writer.msg_counter().is_none());
         if let Err(err) = writer.set_destination_id(UnsignedByteFieldU16::new(0xf1f1).into()) {

src/ecss/verification.rs

@@ -3,18 +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,
 }
 
@@ -24,13 +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();
+        let subservice: MessageSubtypeId = 7.try_into().unwrap();
-        assert_eq!(subservice, Subservice::TmCompletionSuccess);
+        assert_eq!(subservice, MessageSubtypeId::TmCompletionSuccess);
     }
 }

src/seq_count.rs

@@ -1,3 +1,8 @@
+//! # 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;
@@ -9,28 +14,33 @@ use paste::paste;
 /// 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>;
-    const MAX_BIT_WIDTH: usize;
 
+    /// Bit width of the counter.
+    fn max_bit_width(&self) -> usize;
+
+    /// Get the current sequence count value.
     fn get(&self) -> Self::Raw;
 
+    /// Increment the sequence count by one.
     fn increment(&self);
 
-    fn increment_mut(&mut self) {
+    /// Get the current sequence count value and increment the counter by one.
-        self.increment();
-    }
-
     fn get_and_increment(&self) -> Self::Raw {
         let val = self.get();
         self.increment();
         val
     }
 
-    fn get_and_increment_mut(&mut self) -> Self::Raw {
+    /// Set the sequence counter.
-        self.get_and_increment()
+    ///
-    }
+    /// This should not be required by default but can be used to reset the counter
+    /// or initialize it with a custom value.
+    fn set(&self, value: Self::Raw);
 }
 
+/// Simple sequence counter which wraps at ´T::MAX´.
 #[derive(Clone)]
 pub struct SequenceCounterSimple<T: Copy> {
     seq_count: Cell<T>,
@@ -43,13 +53,16 @@ macro_rules! impl_for_primitives {
         $(
             paste! {
                 impl SequenceCounterSimple<$ty> {
-                    pub fn [<new_custom_max_val_ $ty>](max_val: $ty) -> Self {
+                    /// Constructor with a custom maximum value.
+                    pub const fn [<new_custom_max_val_ $ty>](max_val: $ty) -> Self {
                         Self {
                             seq_count: Cell::new(0),
                             max_val,
                         }
                     }
-                    pub fn [<new_ $ty>]() -> Self {
+
+                    /// Generic constructor.
+                    pub const fn [<new_ $ty>]() -> Self {
                         Self {
                             seq_count: Cell::new(0),
                             max_val: $ty::MAX
@@ -65,16 +78,23 @@ macro_rules! impl_for_primitives {
 
                 impl SequenceCounter for SequenceCounterSimple<$ty> {
                     type Raw = $ty;
-                    const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
 
+                    #[inline]
+                    fn max_bit_width(&self) -> usize {
+                        core::mem::size_of::<Self::Raw>() * 8
+                    }
+
+                    #[inline]
                     fn get(&self) -> Self::Raw {
                         self.seq_count.get()
                     }
 
+                    #[inline]
                     fn increment(&self) {
                         self.get_and_increment();
                     }
 
+                    #[inline]
                     fn get_and_increment(&self) -> Self::Raw {
                         let curr_count = self.seq_count.get();
 
@@ -85,6 +105,11 @@ macro_rules! impl_for_primitives {
                         }
                         curr_count
                     }
+
+                    #[inline]
+                    fn set(&self, value: Self::Raw) {
+                        self.seq_count.set(value);
+                    }
                 }
             }
         )+
@@ -100,6 +125,7 @@ pub struct SequenceCounterCcsdsSimple {
 }
 
 impl Default for SequenceCounterCcsdsSimple {
+    #[inline]
     fn default() -> Self {
         Self {
             provider: SequenceCounterSimple::new_custom_max_val_u16(MAX_SEQ_COUNT.as_u16()),
@@ -109,7 +135,6 @@ impl Default for SequenceCounterCcsdsSimple {
 
 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;
@@ -117,134 +142,252 @@ impl SequenceCounter for SequenceCounterCcsdsSimple {
             fn get_and_increment(&self) -> u16;
         }
     }
+
+    #[inline]
+    fn set(&self, value: u16) {
+        if value > MAX_SEQ_COUNT.as_u16() {
+            return;
+        }
+        self.provider.set(value);
+    }
+
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        Self::MAX_BIT_WIDTH
+    }
 }
 
+impl SequenceCounterCcsdsSimple {
+    /// Maximum bit width for CCSDS packet sequence counter is 14 bits.
+    pub const MAX_BIT_WIDTH: usize = 14;
+
+    /// Create a new sequence counter specifically for the sequence count of CCSDS packets.
+    ///
+    /// It has a [Self::MAX_BIT_WIDTH] of 14.
+    pub const fn new() -> Self {
+        Self {
+            provider: SequenceCounterSimple::new_custom_max_val_u16(MAX_SEQ_COUNT.value()),
+        }
+    }
+}
+
+#[cfg(target_has_atomic = "8")]
 impl SequenceCounter for core::sync::atomic::AtomicU8 {
     type Raw = u8;
 
-    const MAX_BIT_WIDTH: usize = 8;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        8
+    }
 
+    #[inline]
     fn get(&self) -> Self::Raw {
         self.load(core::sync::atomic::Ordering::Relaxed)
     }
 
+    #[inline]
     fn increment(&self) {
         self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
     }
+
+    #[inline]
+    fn set(&self, value: u8) {
+        self.store(value, 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;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        16
+    }
 
+    #[inline]
     fn get(&self) -> Self::Raw {
         self.load(core::sync::atomic::Ordering::Relaxed)
     }
 
+    #[inline]
     fn increment(&self) {
         self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
     }
+
+    #[inline]
+    fn set(&self, value: u16) {
+        self.store(value, 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;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        32
+    }
 
+    #[inline]
     fn get(&self) -> Self::Raw {
         self.load(core::sync::atomic::Ordering::Relaxed)
     }
 
+    #[inline]
     fn increment(&self) {
         self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
     }
+
+    #[inline]
+    fn set(&self, value: u32) {
+        self.store(value, 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;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        64
+    }
 
+    #[inline]
     fn get(&self) -> Self::Raw {
         self.load(core::sync::atomic::Ordering::Relaxed)
     }
 
+    #[inline]
     fn increment(&self) {
         self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
     }
+
+    #[inline]
+    fn set(&self, value: u64) {
+        self.store(value, core::sync::atomic::Ordering::Relaxed);
+    }
 }
 
+#[cfg(feature = "portable-atomic")]
 impl SequenceCounter for portable_atomic::AtomicU8 {
     type Raw = u8;
 
-    const MAX_BIT_WIDTH: usize = 8;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        8
+    }
 
     fn get(&self) -> Self::Raw {
-        self.load(core::sync::atomic::Ordering::Relaxed)
+        self.load(portable_atomic::Ordering::Relaxed)
     }
 
     fn increment(&self) {
-        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+
+    fn set(&self, value: Self::Raw) {
+        self.store(value, portable_atomic::Ordering::Relaxed);
     }
 }
 
+#[cfg(feature = "portable-atomic")]
 impl SequenceCounter for portable_atomic::AtomicU16 {
     type Raw = u16;
 
-    const MAX_BIT_WIDTH: usize = 16;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        16
+    }
 
     fn get(&self) -> Self::Raw {
-        self.load(core::sync::atomic::Ordering::Relaxed)
+        self.load(portable_atomic::Ordering::Relaxed)
     }
 
     fn increment(&self) {
-        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+
+    fn set(&self, value: Self::Raw) {
+        self.store(value, portable_atomic::Ordering::Relaxed);
     }
 }
 
+#[cfg(feature = "portable-atomic")]
 impl SequenceCounter for portable_atomic::AtomicU32 {
     type Raw = u32;
 
-    const MAX_BIT_WIDTH: usize = 32;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        32
+    }
 
     fn get(&self) -> Self::Raw {
-        self.load(core::sync::atomic::Ordering::Relaxed)
+        self.load(portable_atomic::Ordering::Relaxed)
     }
 
     fn increment(&self) {
-        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+
+    fn set(&self, value: Self::Raw) {
+        self.store(value, portable_atomic::Ordering::Relaxed);
     }
 }
 
+#[cfg(feature = "portable-atomic")]
 impl SequenceCounter for portable_atomic::AtomicU64 {
     type Raw = u64;
 
-    const MAX_BIT_WIDTH: usize = 64;
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        64
+    }
 
     fn get(&self) -> Self::Raw {
-        self.load(core::sync::atomic::Ordering::Relaxed)
+        self.load(portable_atomic::Ordering::Relaxed)
     }
 
     fn increment(&self) {
-        self.fetch_add(1, core::sync::atomic::Ordering::Relaxed);
+        self.fetch_add(1, portable_atomic::Ordering::Relaxed);
+    }
+
+    fn set(&self, value: Self::Raw) {
+        self.store(value, portable_atomic::Ordering::Relaxed);
     }
 }
 
 impl<T: SequenceCounter + ?Sized> SequenceCounter for &T {
     type Raw = T::Raw;
-    const MAX_BIT_WIDTH: usize = T::MAX_BIT_WIDTH;
 
+    #[inline]
+    fn max_bit_width(&self) -> usize {
+        (**self).max_bit_width()
+    }
+
+    #[inline]
     fn get(&self) -> Self::Raw {
         (**self).get()
     }
 
+    #[inline]
     fn increment(&self) {
         (**self).increment()
     }
+
+    fn set(&self, value: Self::Raw) {
+        (**self).set(value);
+    }
 }
 
+#[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! {
@@ -257,6 +400,7 @@ macro_rules! sync_clonable_seq_counter_impl {
             }
 
             impl [<SequenceCounterSyncCustomWrap $ty:upper>] {
+                /// Generic constructor.
                 pub fn new(max_val: $ty) -> Self {
                     Self {
                         seq_count: core::sync::atomic::[<Atomic $ty:upper>]::new(0),
@@ -267,7 +411,10 @@ macro_rules! sync_clonable_seq_counter_impl {
 
             impl SequenceCounter for [<SequenceCounterSyncCustomWrap $ty:upper>] {
                 type Raw = $ty;
-                const MAX_BIT_WIDTH: usize = core::mem::size_of::<Self::Raw>() * 8;
+
+                fn max_bit_width(&self) -> usize {
+                    core::mem::size_of::<Self::Raw>() * 8
+                }
 
                 fn get(&self) -> $ty {
                     self.seq_count.load(core::sync::atomic::Ordering::Relaxed)
@@ -288,6 +435,10 @@ macro_rules! sync_clonable_seq_counter_impl {
                         },
                     ).unwrap()
                 }
+
+                fn set(&self, value: $ty) {
+                    self.seq_count.store(value, core::sync::atomic::Ordering::Relaxed);
+                }
             }
         }
     };
@@ -302,9 +453,187 @@ sync_clonable_seq_counter_impl!(u32);
 #[cfg(target_has_atomic = "64")]
 sync_clonable_seq_counter_impl!(u64);
 
+/// Modules relying on [std] support.
+#[cfg(feature = "std")]
+pub mod std_mod {
+    use super::*;
+
+    use core::str::FromStr;
+    use std::path::{Path, PathBuf};
+    use std::string::ToString as _;
+    use std::{fs, io};
+
+    /// A persistent file-backed sequence counter that can wrap any other [SequenceCounter]
+    /// implementation which is non-persistent.
+    ///
+    /// In the default configuration, the underlying [SequenceCounter] is initialized from the file
+    /// content, and the file content will only be updated on a manual [Self::save] or on drop.
+    #[derive(Debug, PartialEq, Eq)]
+    pub struct SequenceCounterOnFile<
+        Inner: SequenceCounter<Raw = RawTy>,
+        RawTy: core::fmt::Debug
+            + Copy
+            + Clone
+            + Into<u64>
+            + TryFrom<u64>
+            + FromStr
+            + Default
+            + PartialEq
+            + Eq,
+    > {
+        path: PathBuf,
+        inner: Inner,
+        /// Configures whether the counter value is saved to disk when the object is dropped.
+        ///
+        /// If this is set to [true] which is the default, the sequence counter will only be stored
+        /// to disk if the [Self::save] method is used or the object is dropped. Otherwise, the
+        /// counter will be saved to disk on every [Self::increment] or [Self::set].
+        pub save_on_drop: bool,
+    }
+
+    impl<
+            Inner: SequenceCounter<Raw = RawTy>,
+            RawTy: core::fmt::Debug
+                + Copy
+                + Clone
+                + Into<u64>
+                + TryFrom<u64>
+                + FromStr
+                + Default
+                + PartialEq
+                + Eq,
+        > SequenceCounterOnFile<Inner, RawTy>
+    {
+        /// Initialize a new persistent sequence counter using a file at the given path and
+        /// any non persistent inner [SequenceCounter] implementation.
+        pub fn new<P: AsRef<Path>>(path: P, inner: Inner) -> io::Result<Self> {
+            let path = path.as_ref().to_path_buf();
+            let value = Self::load_from_path(&path);
+            inner.set(value);
+            Ok(Self {
+                path,
+                inner,
+                save_on_drop: true,
+            })
+        }
+
+        fn load_from_path(path: &Path) -> RawTy {
+            let bytes = match fs::read(path) {
+                Ok(b) => b,
+                Err(_) => return Default::default(),
+            };
+
+            // Trim optional single trailing newline (Unix/Windows)
+            let trimmed = match bytes.last() {
+                Some(&b'\n') => &bytes[..bytes.len() - 1],
+                _ => &bytes,
+            };
+
+            // Reject non-ASCII
+            if !trimmed.is_ascii() {
+                return Default::default();
+            }
+
+            // Parse
+            std::str::from_utf8(trimmed)
+                .ok()
+                .and_then(|s| s.parse().ok())
+                .unwrap_or_default()
+        }
+
+        /// Persist the current value to disk (best-effort).
+        pub fn save(&self) -> io::Result<()> {
+            let value = self.inner.get();
+            std::fs::write(&self.path, value.into().to_string())
+        }
+    }
+
+    impl<
+            Inner: SequenceCounter<Raw = RawTy>,
+            RawTy: core::fmt::Debug
+                + Copy
+                + Clone
+                + Into<u64>
+                + TryFrom<u64, Error: core::fmt::Debug>
+                + FromStr
+                + Default
+                + PartialEq
+                + Eq,
+        > SequenceCounter for SequenceCounterOnFile<Inner, RawTy>
+    {
+        type Raw = RawTy;
+
+        fn max_bit_width(&self) -> usize {
+            self.inner.max_bit_width()
+        }
+
+        fn get(&self) -> RawTy {
+            self.inner.get()
+        }
+
+        fn increment(&self) {
+            self.inner.increment();
+
+            if !self.save_on_drop {
+                // persist (ignore I/O errors here; caller can call `save` explicitly)
+                let _ = self.save();
+            }
+        }
+
+        fn set(&self, value: RawTy) {
+            self.inner.set(value);
+            if !self.save_on_drop {
+                // persist (ignore I/O errors here; caller can call `save` explicitly)
+                let _ = self.save();
+            }
+        }
+    }
+
+    impl<
+            Inner: SequenceCounter<Raw = RawTy>,
+            RawTy: core::fmt::Debug
+                + Copy
+                + Clone
+                + Into<u64>
+                + TryFrom<u64>
+                + FromStr
+                + Default
+                + PartialEq
+                + Eq,
+        > Drop for SequenceCounterOnFile<Inner, RawTy>
+    {
+        fn drop(&mut self) {
+            if self.save_on_drop {
+                let _ = self.save();
+            }
+        }
+    }
+
+    /// Type alisas for a CCSDS sequence counter stored on file.
+    pub type SequenceCounterCcsdsOnFile = SequenceCounterOnFile<SequenceCounterCcsdsSimple, u16>;
+
+    impl SequenceCounterCcsdsOnFile {
+        /// Open or create the counter file at `path`.
+        pub fn new_ccsds_counter<P: AsRef<Path>>(path: P) -> io::Result<Self> {
+            SequenceCounterOnFile::new(path, SequenceCounterCcsdsSimple::default())
+        }
+    }
+
+    /// Type alisas for a [u16] sequence counter stored on file.
+    pub type SequenceCounterU16OnFile = SequenceCounterOnFile<SequenceCounterSimple<u16>, u16>;
+
+    impl SequenceCounterU16OnFile {
+        /// Open or create the counter file at `path`.
+        pub fn new_u16_counter<P: AsRef<Path>>(path: P) -> io::Result<Self> {
+            SequenceCounterOnFile::new(path, SequenceCounterSimple::<u16>::default())
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use core::sync::atomic::{AtomicU16, AtomicU32, AtomicU64, AtomicU8};
+    use std::boxed::Box;
 
     use crate::seq_count::{
         SequenceCounter, SequenceCounterCcsdsSimple, SequenceCounterSimple,
@@ -316,6 +645,7 @@ mod tests {
     fn test_u8_counter() {
         let u8_counter = SequenceCounterSimple::<u8>::default();
         assert_eq!(u8_counter.get(), 0);
+        assert_eq!(u8_counter.max_bit_width(), 8);
         assert_eq!(u8_counter.get_and_increment(), 0);
         assert_eq!(u8_counter.get_and_increment(), 1);
         assert_eq!(u8_counter.get(), 2);
@@ -353,55 +683,63 @@ mod tests {
         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();
+        seq_counter.increment();
         assert_eq!(seq_counter.get().into(), 3);
-        assert_eq!(seq_counter.get_and_increment_mut().into(), 3);
+        assert_eq!(seq_counter.get_and_increment().into(), 3);
         assert_eq!(seq_counter.get().into(), 4);
     }
 
     #[test]
     fn test_atomic_counter_u8() {
         let mut sync_u8_counter = AtomicU8::new(0);
+        assert_eq!(sync_u8_counter.max_bit_width(), 8);
         common_counter_test(&mut sync_u8_counter);
     }
 
     #[test]
     fn test_atomic_counter_u16() {
         let mut sync_u16_counter = AtomicU16::new(0);
+        assert_eq!(sync_u16_counter.max_bit_width(), 16);
         common_counter_test(&mut sync_u16_counter);
     }
 
     #[test]
     fn test_atomic_counter_u32() {
         let mut sync_u32_counter = AtomicU32::new(0);
+        assert_eq!(sync_u32_counter.max_bit_width(), 32);
         common_counter_test(&mut sync_u32_counter);
     }
 
     #[test]
     fn test_atomic_counter_u64() {
         let mut sync_u64_counter = AtomicU64::new(0);
+        assert_eq!(sync_u64_counter.max_bit_width(), 64);
         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);
@@ -421,6 +759,7 @@ mod tests {
     }
 
     #[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);
@@ -434,4 +773,56 @@ mod tests {
         }
         assert_eq!(sync_u8_counter.get(), 0);
     }
+
+    #[test]
+    fn test_dyn_compatible() {
+        let counter: Box<dyn SequenceCounter<Raw = u16>> =
+            Box::new(SequenceCounterCcsdsSimple::default());
+        assert_eq!(counter.get(), 0);
+        assert_eq!(counter.max_bit_width(), 14);
+        counter.increment();
+        assert_eq!(counter.get(), 1);
+        assert_eq!(counter.get_and_increment(), 1);
+        assert_eq!(counter.get(), 2);
+    }
+
+    #[test]
+    fn test_persistent_counter() {
+        let tempdir = tempfile::tempdir().expect("failed to create temp dir");
+        let path = tempdir.path().join("seq_count.txt");
+        let mut persistent_counter =
+            crate::seq_count::std_mod::SequenceCounterCcsdsOnFile::new_ccsds_counter(&path)
+                .unwrap();
+        assert_eq!(persistent_counter.get(), 0);
+        assert_eq!(persistent_counter.get_and_increment(), 0);
+        drop(persistent_counter);
+        assert!(path.exists());
+
+        persistent_counter =
+            crate::seq_count::std_mod::SequenceCounterCcsdsOnFile::new_ccsds_counter(
+                tempdir.path().join("seq_count.txt"),
+            )
+            .unwrap();
+        assert_eq!(persistent_counter.get(), 1);
+    }
+
+    #[test]
+    fn test_persistent_couter_manual_save() {
+        let tempdir = tempfile::tempdir().expect("failed to create temp dir");
+        let path = tempdir.path().join("seq_count.txt");
+        let mut persistent_counter =
+            crate::seq_count::std_mod::SequenceCounterCcsdsOnFile::new_ccsds_counter(&path)
+                .unwrap();
+        assert_eq!(persistent_counter.get(), 0);
+        assert_eq!(persistent_counter.get_and_increment(), 0);
+        persistent_counter.save().unwrap();
+        assert!(path.exists());
+        std::mem::forget(persistent_counter);
+        persistent_counter =
+            crate::seq_count::std_mod::SequenceCounterCcsdsOnFile::new_ccsds_counter(
+                tempdir.path().join("seq_count.txt"),
+            )
+            .unwrap();
+        assert_eq!(persistent_counter.get(), 1);
+    }
 }

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::*;

src/time/cuc.rs

@@ -32,6 +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))]
@@ -70,13 +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.
@@ -101,22 +103,34 @@ pub fn fractional_part_from_subsec_ns(res: FractionalResolution, ns: u64) -> Fra
     }
 }
 
+/// 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: u8, counter: u64 },
+    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,
+    /// Data is before the CCSDS epoch.
     #[error("date before ccsds epoch: {0}")]
     DateBeforeCcsdsEpoch(#[from] DateBeforeCcsdsEpochError),
 }
@@ -127,14 +141,20 @@ pub enum 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);
@@ -157,6 +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);
@@ -169,16 +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
@@ -245,17 +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 {
@@ -381,6 +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>,
@@ -423,7 +452,7 @@ impl CucTime {
             .ok_or(CucError::LeapSecondCorrectionError)?;
         let fractions =
             fractional_part_from_subsec_ns(res, unix_time.subsec_millis() as u64 * 10_u64.pow(6));
-        Self::new_generic(WidthCounterPair(4, counter as u32), fractions)
+        Self::new_generic(WidthCounterPair(4, counter), fractions)
     }
 
     /// Most generic constructor which allows full configurability for the counter and for the
@@ -448,21 +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
@@ -474,11 +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)?;
@@ -525,16 +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)
@@ -542,6 +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
@@ -564,6 +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;

src/time/mod.rs

@@ -22,19 +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,
 }
 
@@ -60,44 +70,61 @@ pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCode, u8> {
     CcsdsTimeCode::try_from(raw_bits).map_err(|_| raw_bits)
 }
 
+/// 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);
 
+/// 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 {
+    /// Invalid time code.
     #[error("invalid time code, expected {expected:?}, found {found}")]
-    InvalidTimeCode { expected: CcsdsTimeCode, found: u8 },
+    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,
 }
 
+/// [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()
@@ -131,16 +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
@@ -149,13 +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()];
@@ -164,7 +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>;
 }
 
@@ -174,6 +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
@@ -181,24 +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;
+    /// UNIX time as seconds.
-    fn subsec_nanos(&self) -> u32;
+    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())?
@@ -280,6 +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,
@@ -287,15 +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)?;
@@ -303,27 +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
@@ -393,7 +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,
 }
 

src/util.rs

@@ -1,12 +1,16 @@
+//! # Utility module.
 use crate::ByteConversionError;
 use core::fmt::Debug;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+/// 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;
 }
 
@@ -80,14 +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()];
@@ -96,22 +103,32 @@ pub trait UnsignedEnum {
     }
 }
 
+/// Extension trait for unsigned enumerations.
 pub trait UnsignedEnumExt: UnsignedEnum + 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: usize, value: u64 },
+    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>,
     },
+    /// Error during byte conversion.
     #[error("byte conversion error: {0}")]
     ByteConversionError(#[from] ByteConversionError),
 }
@@ -126,16 +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() {
@@ -175,8 +195,8 @@ impl UnsignedEnum for UnsignedByteField {
     }
 
     #[inline]
-    fn value(&self) -> u64 {
+    fn value_raw(&self) -> u64 {
-        self.value_const()
+        self.value()
     }
 
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
@@ -212,6 +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))]
@@ -220,11 +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
     }
 }
@@ -247,20 +270,29 @@ impl<TYPE: Copy + ToBeBytes + Into<u64>> UnsignedEnum for GenericUnsignedByteFie
     }
 
     #[inline]
-    fn value(&self) -> u64 {
+    fn value_raw(&self) -> u64 {
-        self.value_typed().into()
+        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 {
@@ -351,7 +383,7 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU64 {
 }
 
 #[cfg(test)]
-pub mod tests {
+mod tests {
     use crate::util::{
         UnsignedByteField, UnsignedByteFieldError, UnsignedByteFieldU16, UnsignedByteFieldU32,
         UnsignedByteFieldU64, UnsignedByteFieldU8, UnsignedEnum,
@@ -372,7 +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);
     }
 
@@ -390,7 +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);
     }
 
@@ -408,7 +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);
     }
 
@@ -423,7 +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);
     }