prep v0.6.0

Reviewed-on: #14

.gitignore

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

.idea/runConfigurations/Check.xml

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

.idea/runConfigurations/Test.xml

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

CHANGELOG.md

@@ -8,6 +8,162 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.6.0] 2023-07-06
+
+## Added
+
+- Added new `util` module which contains the following (new) helper modules:
+  - `UnsignedEnum` trait as an abstraction for unsigned byte fields with variable lengths. It is
+    not tied to the ECSS PFC value like the `EcssEnumeration` trait. The method to retrieve
+    the size of the unsigned enumeration in bytes is now called `size`.
+  - `GenericUnsignedByteField<TYPE>` and helper typedefs `UnsignedU8`, `UnsignedU16`, `UnsignedU32`
+    and `UnsignedU64` as helper types implementing `UnsignedEnum`
+  - `UnsignedByteField` as a type-erased helper.
+- Initial CFDP support: Added PDU packet implementation.
+- Added `SerializablePusPacket` as a generic abstraction for PUS packets which are
+  writable.
+- Added new `PusTmZeroCopyWriter` class which allows to set fields on a raw TM packet,
+  which might be more efficient that modification and re-writing a packet with the
+  `PusTm` object.
+
+## Changed
+ 
+- The `EcssEnumeration` now requires the `UnsignedEnum` trait and only adds the `pfc` method to it.
+- Renamed `byte_width` usages to `size` (part of new `UnsignedEnum` trait)
+- Moved `ecss::CRC_CCITT_FALSE` CRC constant to the root module. This CRC type is not just used by
+  the PUS standard, but by the CCSDS Telecommand standard and the CFDP standard as well.
+
+# [v0.5.4] 2023-02-12
+
+## Added
+
+- `Clone` trait requirement for `time::cds::ProvidesDaysLen` trait.
+- Added `Copy` and `Clone` derives for `DaysLen16Bits` and `DaysLen24Bits`.
+
+# [v0.5.3] 2023-02-05
+
+## Added
+
+- `num_enum` dependency to avoid boilerplate code for primtive to enum conversions, for example
+  for the PUS subservices.
+- `ecss.event` module containing a `Subservice` enum.
+- `ecss.verification` module containing a `Subservice` enum.
+- `ecss.scheduling` module containing a `Subservice` enum and some other helper enumerations.
+- `ecss.hk` module containing a `Subservice` enum.
+
+## Changed
+
+- Added missing Service IDs to `ecss.PusServiceId` and marked in `#[non_exhaustive]`.
+
+## Fixed
+
+- `time.UnixTimestamp`: All constructors and `From` conversions now use the `new` constructor,
+  which should cause a correct conversion of 0 subsecond milliseconds to a `None` value.
+
+# [v0.5.2] 2023-01-26
+
+## Added
+
+- Added `.gitignore`.
+
+## Fixed
+
+- Correct implementation of Trait `PartialEq` for `PusTc` and `PusTm`. The previous auto-derivation
+  were incorrect because they also compared fields unrelated to the raw byte representation.
+
+## Changed
+
+- Renamed `PusTc` `raw` method to `raw_bytes` and add better docs to avoid confusion.
+  Deprecate `raw` to avoid breaking change.
+- Added `raw_bytes` method to `PusTm`.
+
+# [v0.5.1] 2023-01-22
+
+## Added
+
+- `time::cds::TimeProvider`
+  - Add `Ord` and `PartialOrd`, use custom `PartialEq` impl to account for precision correctly.
+  - Add `precision_as_ns` function which converts microsecond and picosecond precision values
+    into nanoseconds.
+  - Add conversion trait to convert `cds::TimeProvider<DaysLen16Bits>` into
+    `cds::TimeProvider<DaysLen24Bits>` and vice-versa.
+- `time::UnixTimestamp`
+  - Add `Ord` and `PartialOrd` implementations.
+  - Add `Add<Duration>` and `AddAssign<Duration>` implementations.
+
+## Fixed
+
+- `time::cds::TimeProvider`: Fixed a bug where subsecond milliseconds were not accounted for
+  when the provider has no submillisecond precision.
+
+# [v0.5.0] 2023-01-20
+
+The timestamp of `PusTm` is now optional. See Added and Changed section for details.
+
+## Added
+
+- `PusTmSecondaryHeader`: New `new_simple_no_timestamp` API to create secondary header without
+  timestamp.
+- `PusTm`: Add `new_simple_no_timestamp` method to create TM without timestamp
+- New `UnixTimestamp` abstraction which contains the unix seconds as an `i64`
+  and an optional subsecond millisecond counter (`u16`)
+- `MS_PER_DAY` constant.
+- CUC: Added `from_date_time` and `from_unix_stamp` constructors for time provider.
+- CUC: Add `Add<Duration>` and `AddAssign<Duration>` impl for time provider.
+
+### CDS time module
+
+- Implement `Add<Duration>` and `AddAssign<Duration>` for time providers, which allows
+  easily adding offsets to the providers.
+- Implement `TryFrom<DateTime<Utc>>` for time providers.
+- `get_dyn_time_provider_from_bytes`: Requires `alloc` support and returns
+  the correct `TimeProvider` instance wrapped as a boxed trait object
+  `Box<DynCdsTimeProvider>` by checking the length of days field.
+- Added constructor function to create the time provider
+  from `chrono::DateTime<Utc>` and a generic UNIX timestamp (`i64` seconds
+  and subsecond milliseconds).
+- `MAX_DAYS_24_BITS` which contains maximum value which can be supplied
+  to the days field of a CDS time provider with 24 bits days field width.
+- New `CdsTimestamp` trait which encapsulates common fields for all CDS time providers.
+- `from_unix_secs_with_u24_days` and `from_unix_secs_with_u16_days` which create
+   the time provider from a `UnixTimestamp` reference.
+- `from_dt_with_u16_days`, `from_dt_with_u24_days` and their `..._us_precision` and
+   `..._ps_precision` variants which allow to create time providers from
+   a `chrono::DateTime<Utc>`.
+- Add `from_bytes_with_u24_days` and `from_bytes_with_u16_days` associated methods
+
+## Changed
+
+
+- (breaking) `unix_epoch_to_ccsds_epoch`: Expect and return `i64` instead of `u64` now.
+- (breaking) `ccsds_epoch_to_unix_epoch`: Expect and return `i64` instead of `u64` now.
+- (breaking) `PusTmSecondaryHeader`: Timestamp is optional now, which translates to a
+  timestamp of size 0.
+- (breaking): `PusTm`: Renamed `time_stamp` method to `timestamp`, also returns
+  `Optional<&'src_data [u8]>` now.
+- (breaking): `PusTmSecondaryHeader`: Renamed `time_stamp` field to `timestamp` for consistency.
+- (breaking): Renamed `from_now_with_u24_days_and_us_prec` to `from_now_with_u24_days_us_precision`.
+  Also did the same for the `u16` variant.
+- (breaking): Renamed `from_now_with_u24_days_and_ps_prec` to `from_now_with_u24_days_ps_precision`.
+  Also did the same for the `u16` variant.
+- `CcsdsTimeProvider` trait (breaking):
+  - Add new `unix_stamp` method returning the new `UnixTimeStamp` struct.
+  - Add new  `subsecond_millis` method returning counter `Option<u16>`.
+  - Default impl for `unix_stamp` which re-uses `subsecond_millis` and
+    existing `unix_seconds` method.
+- `TimestampError` (breaking): Add `DateBeforeCcsdsEpoch` error type
+  because new CDS API allow supplying invalid date times before CCSDS epoch.
+  Make `TimestampError` with `#[non_exhaustive]` attribute to prevent
+  future breakages if new error variants are added.
+
+# [v0.4.2] 14.01.2023
+
+## Fixed
+
+- CDS timestamp: Fixed another small logic error for stamp creation from the current
+  time with picosecond precision.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/8
+
 # [v0.4.1] 14.01.2023
 
 ## Fixed
@@ -15,6 +171,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - CDS timestamp: The conversion function from the current time were buggy
   when specifying picoseconds precision, which could lead to overflow
   multiplications and/or incorrect precision fields.
+  PR: https://egit.irs.uni-stuttgart.de/rust/spacepackets/pulls/7
 
 # [v0.4.0] 10.01.2023
 

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "spacepackets"
-version = "0.4.1"
+version = "0.6.0"
 edition = "2021"
 rust-version = "1.60"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]
@@ -15,7 +15,11 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 [dependencies]
 zerocopy = "0.6"
 crc = "3"
-delegate = "0.8"
+delegate = ">=0.8, <0.11"
+
+[dependencies.num_enum]
+version = "0.6"
+default-features = false
 
 [dependencies.serde]
 version = "1"
@@ -32,7 +36,7 @@ version = "0.2"
 default-features = false
 
 [dev-dependencies.postcard]
-version = "1.0"
+version = "1"
 
 [features]
 default = ["std"]

NOTICE

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

README.md

@@ -13,13 +13,15 @@ Currently, this includes the following components:
 
 - Space Packet implementation according to
   [CCSDS Blue Book 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf)
+- CCSDS File Delivery Protocol (CFDP) packet implementations according to
+  [CCSDS Blue Book 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf)
 - PUS Telecommand and PUS Telemetry implementation according to the
   [ECSS-E-ST-70-41C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
 - CUC (CCSDS Unsegmented Time Code) implementation according to
   [CCSDS 301.0-B-4 3.2](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 - CDS (CCSDS Day Segmented Time Code) implementation according to
   [CCSDS 301.0-B-4 3.3](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
-- Some helper types to support ASCII timecodes ad specified in
+- Some helper types to support ASCII timecodes as specified in
   [CCSDS 301.0-B-4 3.5](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 
 # Features

release-checklist.md

@@ -0,0 +1,18 @@
+Checklist for new releases
+=======
+
+# Pre-Release
+
+1. Make sure any new modules are documented sufficiently enough and check docs with
+   `cargo doc --all-features --open`.
+2. Bump version specifier in `Cargo.toml`.
+3. Update `CHANGELOG.md`: Convert `unreleased` section into version section with date and add new
+   `unreleased` section.
+4. Run `cargo test --all-features`.
+5. Run `cargo fmt` and `cargo clippy`. Check `cargo msrv` against MSRV in `Cargo.toml`.
+6. Wait for CI/CD results for EGit and Github. These also check cross-compilation for bare-metal
+   targets.
+
+# Post-Release
+
+1. Create a new release on `EGit` based on the release branch.

src/cfdp/lv.rs

@@ -0,0 +1,308 @@
+//! Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
+use crate::cfdp::TlvLvError;
+use crate::{ByteConversionError, SizeMissmatch};
+use core::str::Utf8Error;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::string::String;
+
+pub const MIN_LV_LEN: usize = 1;
+
+/// Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
+///
+/// # Lifetimes
+///  * `data`: If the LV is generated from a raw bytestream, this will be the lifetime of
+///    the raw bytestream. If the LV is generated from a raw slice or a similar data reference,
+///    this will be the lifetime of that data reference.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct Lv<'data> {
+    data: Option<&'data [u8]>,
+}
+
+pub(crate) fn generic_len_check_data_serialization(
+    buf: &[u8],
+    data_len: usize,
+    min_overhead: usize,
+) -> Result<(), ByteConversionError> {
+    if buf.len() < data_len + min_overhead {
+        return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            found: buf.len(),
+            expected: data_len + min_overhead,
+        }));
+    }
+    Ok(())
+}
+
+pub(crate) fn generic_len_check_deserialization(
+    buf: &[u8],
+    min_overhead: usize,
+) -> Result<(), ByteConversionError> {
+    if buf.len() < min_overhead {
+        return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            found: buf.len(),
+            expected: min_overhead,
+        }));
+    }
+    Ok(())
+}
+
+impl<'data> Lv<'data> {
+    pub fn new(data: &[u8]) -> Result<Lv, TlvLvError> {
+        if data.len() > u8::MAX as usize {
+            return Err(TlvLvError::DataTooLarge(data.len()));
+        }
+        Ok(Lv { data: Some(data) })
+    }
+
+    /// Creates a LV with an empty value field.
+    pub fn new_empty() -> Lv<'data> {
+        Lv { data: None }
+    }
+
+    /// Helper function to build a string LV. This is especially useful for the file or directory
+    /// path LVs
+    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvError> {
+        Self::new(str_slice.as_bytes())
+    }
+
+    /// Helper function to build a string LV. This is especially useful for the file or directory
+    /// path LVs
+    #[cfg(feature = "std")]
+    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvError> {
+        Self::new(string.as_bytes())
+    }
+
+    /// Returns the length of the value part, not including the length byte.
+    pub fn len_value(&self) -> usize {
+        if self.data.is_none() {
+            return 0;
+        }
+        self.data.unwrap().len()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    pub fn len_full(&self) -> usize {
+        self.len_value() + 1
+    }
+
+    /// Checks whether the value field is empty.
+    pub fn is_empty(&self) -> bool {
+        self.data.is_none()
+    }
+
+    pub fn value(&self) -> Option<&[u8]> {
+        self.data
+    }
+
+    /// Convenience function to extract the value as a [str]. This is useful if the LV is
+    /// known to contain a [str], for example being a file name.
+    pub fn value_as_str(&self) -> Option<Result<&'data str, Utf8Error>> {
+        self.data?;
+        Some(core::str::from_utf8(self.data.unwrap()))
+    }
+
+    /// Writes the LV to a raw buffer. Please note that the first byte will contain the length
+    /// of the value, but the values may not exceed a length of [u8::MAX].
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        generic_len_check_data_serialization(buf, self.len_value(), MIN_LV_LEN)?;
+        Ok(self.write_to_be_bytes_no_len_check(buf))
+    }
+
+    /// Reads a LV  from a raw buffer.
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Lv<'data>, ByteConversionError> {
+        generic_len_check_deserialization(buf, MIN_LV_LEN)?;
+        Self::from_be_bytes_no_len_check(buf)
+    }
+
+    pub(crate) fn write_to_be_bytes_no_len_check(&self, buf: &mut [u8]) -> usize {
+        if self.data.is_none() {
+            buf[0] = 0;
+            return MIN_LV_LEN;
+        }
+        let data = self.data.unwrap();
+        // Length check in constructor ensures the length always has a valid value.
+        buf[0] = data.len() as u8;
+        buf[MIN_LV_LEN..data.len() + MIN_LV_LEN].copy_from_slice(data);
+        MIN_LV_LEN + data.len()
+    }
+
+    pub(crate) fn from_be_bytes_no_len_check(
+        buf: &'data [u8],
+    ) -> Result<Lv<'data>, ByteConversionError> {
+        let value_len = buf[0] as usize;
+        generic_len_check_deserialization(buf, value_len + MIN_LV_LEN)?;
+        let mut data = None;
+        if value_len > 0 {
+            data = Some(&buf[MIN_LV_LEN..MIN_LV_LEN + value_len])
+        }
+        Ok(Self { data })
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::TlvLvError;
+    use crate::ByteConversionError;
+    use std::string::String;
+
+    #[test]
+    fn test_basic() {
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv_res = Lv::new(&lv_data);
+        assert!(lv_res.is_ok());
+        let lv = lv_res.unwrap();
+        assert!(lv.value().is_some());
+        let val = lv.value().unwrap();
+        assert_eq!(val[0], 1);
+        assert_eq!(val[1], 2);
+        assert_eq!(val[2], 3);
+        assert_eq!(val[3], 4);
+        assert!(!lv.is_empty());
+        assert_eq!(lv.len_full(), 5);
+        assert_eq!(lv.len_value(), 4);
+    }
+
+    #[test]
+    fn test_empty() {
+        let lv_empty = Lv::new_empty();
+        assert_eq!(lv_empty.len_value(), 0);
+        assert_eq!(lv_empty.len_full(), 1);
+        assert!(lv_empty.is_empty());
+        assert_eq!(lv_empty.value(), None);
+        let mut buf: [u8; 4] = [0xff; 4];
+        let res = lv_empty.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 1);
+        assert_eq!(buf[0], 0);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv_res = Lv::new(&lv_data);
+        assert!(lv_res.is_ok());
+        let lv = lv_res.unwrap();
+        let mut buf: [u8; 16] = [0; 16];
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 5);
+        assert_eq!(buf[0], 4);
+        assert_eq!(buf[1], 1);
+        assert_eq!(buf[2], 2);
+        assert_eq!(buf[3], 3);
+        assert_eq!(buf[4], 4);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let mut buf: [u8; 16] = [0; 16];
+        buf[0] = 4;
+        buf[1] = 1;
+        buf[2] = 2;
+        buf[3] = 3;
+        buf[4] = 4;
+        let lv = Lv::from_bytes(&buf);
+        assert!(lv.is_ok());
+        let lv = lv.unwrap();
+        assert!(!lv.is_empty());
+        assert!(lv.value().is_some());
+        assert_eq!(lv.len_value(), 4);
+        assert_eq!(lv.len_full(), 5);
+        let val = lv.value().unwrap();
+        assert_eq!(val[0], 1);
+        assert_eq!(val[1], 2);
+        assert_eq!(val[2], 3);
+        assert_eq!(val[3], 4);
+    }
+
+    #[test]
+    fn test_deserialization_empty() {
+        let buf: [u8; 2] = [0; 2];
+        let lv_empty = Lv::from_bytes(&buf);
+        assert!(lv_empty.is_ok());
+        let lv_empty = lv_empty.unwrap();
+        assert!(lv_empty.is_empty());
+        assert!(lv_empty.value().is_none());
+    }
+
+    #[test]
+    fn test_data_too_large() {
+        let data_big: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
+        let lv = Lv::new(&data_big);
+        assert!(lv.is_err());
+        let error = lv.unwrap_err();
+        if let TlvLvError::DataTooLarge(size) = error {
+            assert_eq!(size, u8::MAX as usize + 1);
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+
+    #[test]
+    fn test_serialization_buf_too_small() {
+        let mut buf: [u8; 3] = [0; 3];
+        let lv_data: [u8; 4] = [1, 2, 3, 4];
+        let lv = Lv::new(&lv_data).unwrap();
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let ByteConversionError::ToSliceTooSmall(missmatch) = error {
+            assert_eq!(missmatch.expected, 5);
+            assert_eq!(missmatch.found, 3);
+        } else {
+            panic!("invalid error {}", error);
+        }
+    }
+
+    #[test]
+    fn test_deserialization_buf_too_small() {
+        let mut buf: [u8; 3] = [0; 3];
+        buf[0] = 4;
+        let res = Lv::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let ByteConversionError::FromSliceTooSmall(missmatch) = error {
+            assert_eq!(missmatch.found, 3);
+            assert_eq!(missmatch.expected, 5);
+        } else {
+            panic!("invalid error {}", error);
+        }
+    }
+
+    fn verify_test_str_lv(lv: Lv) {
+        let mut buf: [u8; 16] = [0; 16];
+        let res = lv.write_to_be_bytes(&mut buf);
+        assert!(res.is_ok());
+        let res = res.unwrap();
+        assert_eq!(res, 8 + 1);
+        assert_eq!(buf[0], 8);
+        assert_eq!(buf[1], 't' as u8);
+        assert_eq!(buf[2], 'e' as u8);
+        assert_eq!(buf[3], 's' as u8);
+        assert_eq!(buf[4], 't' as u8);
+        assert_eq!(buf[5], '.' as u8);
+        assert_eq!(buf[6], 'b' as u8);
+        assert_eq!(buf[7], 'i' as u8);
+        assert_eq!(buf[8], 'n' as u8);
+    }
+    #[test]
+    fn test_str_helper() {
+        let test_str = "test.bin";
+        let str_lv = Lv::new_from_str(test_str);
+        assert!(str_lv.is_ok());
+        verify_test_str_lv(str_lv.unwrap());
+    }
+
+    #[test]
+    fn test_string_helper() {
+        let string = String::from("test.bin");
+        let str_lv = Lv::new_from_string(&string);
+        assert!(str_lv.is_ok());
+        verify_test_str_lv(str_lv.unwrap());
+    }
+}

src/cfdp/mod.rs

@@ -0,0 +1,203 @@
+//! Low-level CCSDS File Delivery Protocol (CFDP) support according to [CCSDS 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf).
+use crate::ByteConversionError;
+use core::fmt::{Display, Formatter};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub mod lv;
+pub mod pdu;
+pub mod tlv;
+
+/// This is the name of the standard this module is based on.
+pub const CFDP_VERSION_2_NAME: &str = "CCSDS 727.0-B-5";
+/// Currently, only this version is supported.
+pub const CFDP_VERSION_2: u8 = 0b001;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum PduType {
+    FileDirective = 0,
+    FileData = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum Direction {
+    TowardsReceiver = 0,
+    TowardsSender = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum TransmissionMode {
+    Acknowledged = 0,
+    Unacknowledged = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum CrcFlag {
+    NoCrc = 0,
+    WithCrc = 1,
+}
+
+/// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum SegmentMetadataFlag {
+    NotPresent = 0,
+    Present = 1,
+}
+
+/// Always 0 and ignored for File Directive PDUs (CCSDS 727.0-B-5 P.75)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum SegmentationControl {
+    NoRecordBoundaryPreservation = 0,
+    WithRecordBoundaryPreservation = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FaultHandlerCode {
+    NoticeOfCancellation = 0b0001,
+    NoticeOfSuspension = 0b0010,
+    IgnoreError = 0b0011,
+    AbandonTransaction = 0b0100,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum LenInBytes {
+    ZeroOrNone = 0,
+    OneByte = 1,
+    TwoBytes = 2,
+    ThreeBytes = 4,
+    FourBytes = 8,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum ConditionCode {
+    /// This is not an error condition for which a faulty handler override can be specified
+    NoError = 0b0000,
+    PositiveAckLimitReached = 0b0001,
+    KeepAliveLimitReached = 0b0010,
+    InvalidTransmissionMode = 0b0011,
+    FilestoreRejection = 0b0100,
+    FileChecksumFailure = 0b0101,
+    FileSizeError = 0b0110,
+    NakLimitReached = 0b0111,
+    InactivityDetected = 0b1000,
+    CheckLimitReached = 0b1001,
+    UnsupportedChecksumType = 0b1011,
+    /// Not an actual fault condition for which fault handler overrides can be specified
+    SuspendRequestReceived = 0b1110,
+    /// Not an actual fault condition for which fault handler overrides can be specified
+    CancelRequestReceived = 0b1111,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum LargeFileFlag {
+    /// 32 bit maximum file size and FSS size
+    Normal = 0,
+    /// 64 bit maximum file size and FSS size
+    Large = 1,
+}
+
+/// Checksum types according to the
+/// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/)
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum ChecksumType {
+    /// Modular legacy checksum
+    Modular = 0,
+    Crc32Proximity1 = 1,
+    Crc32C = 2,
+    /// Polynomial: 0x4C11DB7. Preferred checksum for now.
+    Crc32 = 3,
+    NullChecksum = 15,
+}
+
+pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum TlvLvError {
+    DataTooLarge(usize),
+    ByteConversionError(ByteConversionError),
+    /// First value: Found value. Second value: Expected value if there is one.
+    InvalidTlvTypeField((u8, Option<u8>)),
+    /// Logically invalid value length detected. The value length may not exceed 255 bytes.
+    /// Depending on the concrete TLV type, the value length may also be logically invalid.
+    InvalidValueLength(usize),
+    /// Only applies to filestore requests and responses. Second name was missing where one is
+    /// expected.
+    SecondNameMissing,
+    /// Invalid action code for filestore requests or responses.
+    InvalidFilestoreActionCode(u8),
+}
+
+impl From<ByteConversionError> for TlvLvError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl Display for TlvLvError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            TlvLvError::DataTooLarge(data_len) => {
+                write!(
+                    f,
+                    "data with size {} larger than allowed {} bytes",
+                    data_len,
+                    u8::MAX
+                )
+            }
+            TlvLvError::ByteConversionError(e) => {
+                write!(f, "{}", e)
+            }
+            TlvLvError::InvalidTlvTypeField((found, expected)) => {
+                write!(
+                    f,
+                    "invalid TLV type field, found {found}, possibly expected {expected:?}"
+                )
+            }
+            TlvLvError::InvalidValueLength(len) => {
+                write!(f, "invalid value length {len} detected")
+            }
+            TlvLvError::SecondNameMissing => {
+                write!(f, "second name missing for filestore request or response")
+            }
+            TlvLvError::InvalidFilestoreActionCode(raw) => {
+                write!(f, "invalid filestore action code with raw value {raw}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for TlvLvError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            TlvLvError::ByteConversionError(e) => Some(e),
+            _ => None,
+        }
+    }
+}

src/cfdp/pdu/eof.rs

@@ -0,0 +1,206 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::EntityIdTlv;
+use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
+use crate::{ByteConversionError, SizeMissmatch};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+/// Finished PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.2.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct EofPdu {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    file_checksum: u32,
+    file_size: u64,
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl EofPdu {
+    pub fn new_no_error(pdu_header: PduHeader, file_checksum: u32, file_size: u64) -> Self {
+        let mut eof_pdu = Self {
+            pdu_header,
+            condition_code: ConditionCode::NoError,
+            file_checksum,
+            file_size,
+            fault_location: None,
+        };
+        eof_pdu.pdu_header.pdu_datafield_len = eof_pdu.calc_pdu_datafield_len() as u16;
+        eof_pdu
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn file_checksum(&self) -> u32 {
+        self.file_checksum
+    }
+
+    pub fn file_size(&self) -> u64 {
+        self.file_size
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        // One directive type octet, 4 bits condition code, 4 spare bits.
+        let mut len = 2 + core::mem::size_of::<u32>() + 4;
+        if self.pdu_header.pdu_conf.file_flag == LargeFileFlag::Large {
+            len += 4;
+        }
+        if let Some(fault_location) = self.fault_location {
+            len += fault_location.len_full();
+        }
+        len
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.written_len();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: expected_len,
+            })
+            .into());
+        }
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = (self.condition_code as u8) << 4;
+        current_idx += 1;
+        buf[current_idx..current_idx + 4].copy_from_slice(&self.file_checksum.to_be_bytes());
+        current_idx += 4;
+        current_idx += write_fss_field(
+            self.pdu_header.pdu_conf.file_flag,
+            self.file_size,
+            &mut buf[current_idx..],
+        )?;
+        if let Some(fault_location) = self.fault_location {
+            current_idx += fault_location.write_to_be_bytes(buf)?;
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<EofPdu, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let is_large_file = pdu_header.pdu_conf.file_flag == LargeFileFlag::Large;
+        let mut min_expected_len = 2 + 4 + 4;
+        if is_large_file {
+            min_expected_len += 4;
+        }
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType((buf[current_idx], FileDirectiveType::EofPdu))
+        })?;
+        if directive_type != FileDirectiveType::EofPdu {
+            return Err(PduError::WrongDirectiveType((
+                directive_type,
+                FileDirectiveType::EofPdu,
+            )));
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        current_idx += 1;
+        let file_checksum =
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap());
+        current_idx += 4;
+        let (fss_field_len, file_size) =
+            read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx..]);
+        current_idx += fss_field_len;
+        let mut fault_location = None;
+        if condition_code != ConditionCode::NoError && current_idx < full_len_without_crc {
+            fault_location = Some(EntityIdTlv::from_bytes(&buf[current_idx..])?);
+        }
+        Ok(Self {
+            pdu_header,
+            condition_code,
+            file_checksum,
+            file_size,
+            fault_location,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::eof::EofPdu;
+    use crate::cfdp::pdu::tests::{common_pdu_conf, verify_raw_header};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
+
+    #[test]
+    fn test_basic() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        assert_eq!(eof_pdu.written_len(), pdu_header.header_len() + 2 + 4 + 4);
+        assert_eq!(eof_pdu.file_checksum(), 0x01020304);
+        assert_eq!(eof_pdu.file_size(), 12);
+        assert_eq!(eof_pdu.condition_code(), ConditionCode::NoError);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = eof_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, eof_pdu.written_len());
+        verify_raw_header(eof_pdu.pdu_header(), &buf);
+        let mut current_idx = eof_pdu.pdu_header().header_len();
+        buf[current_idx] = FileDirectiveType::EofPdu as u8;
+        current_idx += 1;
+        assert_eq!(
+            (buf[current_idx] >> 4) & 0b1111,
+            ConditionCode::NoError as u8
+        );
+        current_idx += 1;
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            0x01020304
+        );
+        current_idx += 4;
+        assert_eq!(
+            u32::from_be_bytes(buf[current_idx..current_idx + 4].try_into().unwrap()),
+            12
+        );
+        current_idx += 4;
+        assert_eq!(current_idx, written);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let pdu_conf = common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal);
+        let pdu_header = PduHeader::new_no_file_data(pdu_conf, 0);
+        let eof_pdu = EofPdu::new_no_error(pdu_header, 0x01020304, 12);
+        let mut buf: [u8; 64] = [0; 64];
+        eof_pdu.write_to_bytes(&mut buf).unwrap();
+        let eof_read_back = EofPdu::from_bytes(&buf);
+        if !eof_read_back.is_ok() {
+            let e = eof_read_back.unwrap_err();
+            panic!("deserialization failed with: {e}")
+        }
+        let eof_read_back = eof_read_back.unwrap();
+        assert_eq!(eof_read_back, eof_pdu);
+    }
+}

src/cfdp/pdu/file_data.rs

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

src/cfdp/pdu/finished.rs

@@ -0,0 +1,336 @@
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::{EntityIdTlv, Tlv, TlvType, TlvTypeField};
+use crate::cfdp::{ConditionCode, CrcFlag, PduType, TlvLvError};
+use crate::{ByteConversionError, SizeMissmatch};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum DeliveryCode {
+    Complete = 0,
+    Incomplete = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FileStatus {
+    DiscardDeliberately = 0b00,
+    DiscardedFsRejection = 0b01,
+    Retained = 0b10,
+    Unreported = 0b11,
+}
+
+/// Finished PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.3.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FinishedPdu<'fs_responses> {
+    pdu_header: PduHeader,
+    condition_code: ConditionCode,
+    delivery_code: DeliveryCode,
+    file_status: FileStatus,
+    fs_responses: Option<&'fs_responses [u8]>,
+    fault_location: Option<EntityIdTlv>,
+}
+
+impl<'fs_responses> FinishedPdu<'fs_responses> {
+    /// Default finished PDU: No error (no fault location field) and no filestore responses.
+    pub fn new_default(
+        pdu_header: PduHeader,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+    ) -> Self {
+        Self::new_generic(
+            pdu_header,
+            ConditionCode::NoError,
+            delivery_code,
+            file_status,
+            None,
+            None,
+        )
+    }
+
+    pub fn new_with_error(
+        pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+        fault_location: EntityIdTlv,
+    ) -> Self {
+        Self::new_generic(
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            None,
+            Some(fault_location),
+        )
+    }
+
+    pub fn new_generic(
+        mut pdu_header: PduHeader,
+        condition_code: ConditionCode,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+        fs_responses: Option<&'fs_responses [u8]>,
+        fault_location: Option<EntityIdTlv>,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileDirective;
+        let mut finished_pdu = Self {
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            fs_responses,
+            fault_location,
+        };
+        finished_pdu.pdu_header.pdu_datafield_len = finished_pdu.calc_pdu_datafield_len() as u16;
+        finished_pdu
+    }
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    pub fn condition_code(&self) -> ConditionCode {
+        self.condition_code
+    }
+
+    pub fn delivery_code(&self) -> DeliveryCode {
+        self.delivery_code
+    }
+
+    pub fn file_status(&self) -> FileStatus {
+        self.file_status
+    }
+
+    pub fn filestore_responses(&self) -> Option<&'fs_responses [u8]> {
+        self.fs_responses
+    }
+
+    pub fn fault_location(&self) -> Option<EntityIdTlv> {
+        self.fault_location
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        let mut base_len = 2;
+        if let Some(fs_responses) = self.fs_responses {
+            base_len += fs_responses.len();
+        }
+        if let Some(fault_location) = self.fault_location {
+            base_len += fault_location.len_full();
+        }
+        base_len
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.written_len();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: expected_len,
+            })
+            .into());
+        }
+
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::FinishedPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = ((self.condition_code as u8) << 4)
+            | ((self.delivery_code as u8) << 2)
+            | self.file_status as u8;
+        current_idx += 1;
+        if let Some(fs_responses) = self.fs_responses {
+            buf[current_idx..current_idx + fs_responses.len()].copy_from_slice(fs_responses);
+            current_idx += fs_responses.len();
+        }
+        if let Some(fault_location) = self.fault_location {
+            current_idx += fault_location.write_to_be_bytes(&mut buf[current_idx..])?;
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    /// Generates [Self] from a raw bytestream.
+    pub fn from_bytes(buf: &'fs_responses [u8]) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let min_expected_len = current_idx + 2;
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType((buf[current_idx], FileDirectiveType::FinishedPdu))
+        })?;
+        if directive_type != FileDirectiveType::FinishedPdu {
+            return Err(PduError::WrongDirectiveType((
+                directive_type,
+                FileDirectiveType::FinishedPdu,
+            )));
+        }
+        current_idx += 1;
+        let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)
+            .map_err(|_| PduError::InvalidConditionCode((buf[current_idx] >> 4) & 0b1111))?;
+        // Unwrap is okay here for both of the following operations which can not fail.
+        let delivery_code = DeliveryCode::try_from((buf[current_idx] >> 2) & 0b1).unwrap();
+        let file_status = FileStatus::try_from(buf[current_idx] & 0b11).unwrap();
+        current_idx += 1;
+        let (fs_responses, fault_location) =
+            Self::parse_tlv_fields(current_idx, full_len_without_crc, buf)?;
+        Ok(Self {
+            pdu_header,
+            condition_code,
+            delivery_code,
+            file_status,
+            fs_responses,
+            fault_location,
+        })
+    }
+
+    fn parse_tlv_fields(
+        mut current_idx: usize,
+        full_len_without_crc: usize,
+        buf: &'fs_responses [u8],
+    ) -> Result<(Option<&'fs_responses [u8]>, Option<EntityIdTlv>), PduError> {
+        let mut fs_responses = None;
+        let mut fault_location = None;
+        let start_of_fs_responses = current_idx;
+        // There are leftover filestore response(s) and/or a fault location field.
+        while current_idx < full_len_without_crc {
+            let next_tlv = Tlv::from_bytes(&buf[current_idx..])?;
+            match next_tlv.tlv_type_field() {
+                TlvTypeField::Standard(tlv_type) => {
+                    if tlv_type == TlvType::FilestoreResponse {
+                        current_idx += next_tlv.len_full();
+                        if current_idx == full_len_without_crc {
+                            fs_responses = Some(&buf[start_of_fs_responses..current_idx]);
+                        }
+                    } else if tlv_type == TlvType::EntityId {
+                        // At least one FS response is included.
+                        if current_idx > full_len_without_crc {
+                            fs_responses = Some(&buf[start_of_fs_responses..current_idx]);
+                        }
+                        fault_location = Some(EntityIdTlv::from_bytes(&buf[current_idx..])?);
+                        current_idx += fault_location.as_ref().unwrap().len_full();
+                        // This is considered a configuration error: The entity ID has to be the
+                        // last TLV, everything else would break the whole handling of the packet
+                        // TLVs.
+                        if current_idx != full_len_without_crc {
+                            return Err(PduError::FormatError);
+                        }
+                    } else {
+                        return Err(TlvLvError::InvalidTlvTypeField((tlv_type as u8, None)).into());
+                    }
+                }
+                TlvTypeField::Custom(raw) => {
+                    return Err(TlvLvError::InvalidTlvTypeField((raw, None)).into());
+                }
+            }
+        }
+        Ok((fs_responses, fault_location))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::finished::{DeliveryCode, FileStatus, FinishedPdu};
+    use crate::cfdp::pdu::tests::{common_pdu_conf, verify_raw_header};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
+
+    fn generic_finished_pdu(
+        crc_flag: CrcFlag,
+        fss: LargeFileFlag,
+        delivery_code: DeliveryCode,
+        file_status: FileStatus,
+    ) -> FinishedPdu<'static> {
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        FinishedPdu::new_default(pdu_header, delivery_code, file_status)
+    }
+
+    #[test]
+    fn test_basic() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        assert_eq!(finished_pdu.condition_code(), ConditionCode::NoError);
+        assert_eq!(finished_pdu.delivery_code(), DeliveryCode::Complete);
+        assert_eq!(finished_pdu.file_status(), FileStatus::Retained);
+        assert_eq!(finished_pdu.filestore_responses(), None);
+        assert_eq!(finished_pdu.fault_location(), None);
+        assert_eq!(finished_pdu.pdu_header().pdu_datafield_len, 2);
+    }
+
+    fn generic_serialization_test_no_error(delivery_code: DeliveryCode, file_status: FileStatus) {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            delivery_code,
+            file_status,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        let written = finished_pdu.write_to_bytes(&mut buf);
+        assert!(written.is_ok());
+        let written = written.unwrap();
+        assert_eq!(written, finished_pdu.written_len());
+        assert_eq!(written, finished_pdu.pdu_header().header_len() + 2);
+        verify_raw_header(finished_pdu.pdu_header(), &buf);
+        let mut current_idx = finished_pdu.pdu_header().header_len();
+        assert_eq!(buf[current_idx], FileDirectiveType::FinishedPdu as u8);
+        current_idx += 1;
+        assert_eq!(
+            (buf[current_idx] >> 4) & 0b1111,
+            ConditionCode::NoError as u8
+        );
+        assert_eq!((buf[current_idx] >> 2) & 0b1, delivery_code as u8);
+        assert_eq!(buf[current_idx] & 0b11, file_status as u8);
+        assert_eq!(current_idx + 1, written);
+    }
+
+    #[test]
+    fn test_serialization_simple() {
+        generic_serialization_test_no_error(DeliveryCode::Complete, FileStatus::Retained);
+    }
+
+    #[test]
+    fn test_serialization_simple_2() {
+        generic_serialization_test_no_error(
+            DeliveryCode::Incomplete,
+            FileStatus::DiscardDeliberately,
+        );
+    }
+
+    #[test]
+    fn test_serialization_simple_3() {
+        generic_serialization_test_no_error(DeliveryCode::Incomplete, FileStatus::Unreported);
+    }
+
+    #[test]
+    fn test_deserialization_simple() {
+        let finished_pdu = generic_finished_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            DeliveryCode::Complete,
+            FileStatus::Retained,
+        );
+        let mut buf: [u8; 64] = [0; 64];
+        finished_pdu.write_to_bytes(&mut buf).unwrap();
+        let read_back = FinishedPdu::from_bytes(&buf);
+        assert!(read_back.is_ok());
+        let read_back = read_back.unwrap();
+        assert_eq!(finished_pdu, read_back);
+    }
+}

src/cfdp/pdu/metadata.rs

@@ -0,0 +1,527 @@
+use crate::cfdp::lv::Lv;
+use crate::cfdp::pdu::{
+    add_pdu_crc, generic_length_checks_pdu_deserialization, read_fss_field, write_fss_field,
+    FileDirectiveType, PduError, PduHeader,
+};
+use crate::cfdp::tlv::Tlv;
+use crate::cfdp::{ChecksumType, CrcFlag, LargeFileFlag, PduType};
+use crate::{ByteConversionError, SizeMissmatch};
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct MetadataGenericParams {
+    closure_requested: bool,
+    checksum_type: ChecksumType,
+    file_size: u64,
+}
+
+impl MetadataGenericParams {
+    pub fn new(closure_requested: bool, checksum_type: ChecksumType, file_size: u64) -> Self {
+        Self {
+            closure_requested,
+            checksum_type,
+            file_size,
+        }
+    }
+}
+
+pub fn build_metadata_opts_from_slice(
+    buf: &mut [u8],
+    tlvs: &[Tlv],
+) -> Result<usize, ByteConversionError> {
+    let mut written = 0;
+    for tlv in tlvs {
+        written += tlv.write_to_bytes(&mut buf[written..])?;
+    }
+    Ok(written)
+}
+
+#[cfg(feature = "alloc")]
+pub fn build_metadata_opts_from_vec(
+    buf: &mut [u8],
+    tlvs: &Vec<Tlv>,
+) -> Result<usize, ByteConversionError> {
+    build_metadata_opts_from_slice(buf, tlvs.as_slice())
+}
+
+/// Helper structure to loop through all options of a metadata PDU. It should be noted that
+/// iterators in Rust are not fallible, but the TLV creation can fail, for example if the raw TLV
+/// data is invalid for some reason. In that case, the iterator will yield [None] because there
+/// is no way to recover from this.
+///
+/// The user can accumulate the length of all TLVs yielded by the iterator and compare it against
+/// the full length of the options to check whether the iterator was able to parse all TLVs
+/// successfully.
+pub struct OptionsIter<'opts> {
+    opt_buf: &'opts [u8],
+    current_idx: usize,
+}
+
+impl<'opts> Iterator for OptionsIter<'opts> {
+    type Item = Tlv<'opts>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.current_idx == self.opt_buf.len() {
+            return None;
+        }
+        let tlv = Tlv::from_bytes(&self.opt_buf[self.current_idx..]);
+        // There are not really fallible iterators so we can't continue here..
+        if tlv.is_err() {
+            return None;
+        }
+        let tlv = tlv.unwrap();
+        self.current_idx += tlv.len_full();
+        Some(tlv)
+    }
+}
+
+/// Metadata PDU abstraction.
+///
+/// For more information, refer to CFDP chapter 5.2.5.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct MetadataPdu<'src_name, 'dest_name, 'opts> {
+    pdu_header: PduHeader,
+    metadata_params: MetadataGenericParams,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    src_file_name: Lv<'src_name>,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    dest_file_name: Lv<'dest_name>,
+    options: Option<&'opts [u8]>,
+}
+
+impl<'src_name, 'dest_name, 'opts> MetadataPdu<'src_name, 'dest_name, 'opts> {
+    pub fn new_no_opts(
+        pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+    ) -> Self {
+        Self::new(
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            None,
+        )
+    }
+
+    pub fn new_with_opts(
+        pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+        options: &'opts [u8],
+    ) -> Self {
+        Self::new(
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            Some(options),
+        )
+    }
+
+    pub fn new(
+        mut pdu_header: PduHeader,
+        metadata_params: MetadataGenericParams,
+        src_file_name: Lv<'src_name>,
+        dest_file_name: Lv<'dest_name>,
+        options: Option<&'opts [u8]>,
+    ) -> Self {
+        pdu_header.pdu_type = PduType::FileDirective;
+        let mut pdu = Self {
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options,
+        };
+        pdu.pdu_header.pdu_datafield_len = pdu.calc_pdu_datafield_len() as u16;
+        pdu
+    }
+
+    pub fn src_file_name(&self) -> Lv<'src_name> {
+        self.src_file_name
+    }
+
+    pub fn dest_file_name(&self) -> Lv<'dest_name> {
+        self.dest_file_name
+    }
+
+    pub fn options(&self) -> Option<&'opts [u8]> {
+        self.options
+    }
+
+    /// Yield an iterator which can be used to loop through all options. Returns [None] if the
+    /// options field is empty.
+    pub fn options_iter(&self) -> Option<OptionsIter<'opts>> {
+        self.options?;
+        Some(OptionsIter {
+            opt_buf: self.options.unwrap(),
+            current_idx: 0,
+        })
+    }
+
+    pub fn written_len(&self) -> usize {
+        self.pdu_header.header_len() + self.calc_pdu_datafield_len()
+    }
+
+    fn calc_pdu_datafield_len(&self) -> usize {
+        // One directve type octet and one byte of the directive parameter field.
+        let mut len = 2;
+        if self.pdu_header.common_pdu_conf().file_flag == LargeFileFlag::Large {
+            len += 8;
+        } else {
+            len += 4;
+        }
+        len += self.src_file_name.len_full();
+        len += self.dest_file_name.len_full();
+        if let Some(opts) = self.options {
+            len += opts.len();
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            len += 2;
+        }
+        len
+    }
+
+    pub fn pdu_header(&self) -> &PduHeader {
+        &self.pdu_header
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        let expected_len = self.written_len();
+        if buf.len() < expected_len {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: expected_len,
+            })
+            .into());
+        }
+
+        let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
+        buf[current_idx] = FileDirectiveType::MetadataPdu as u8;
+        current_idx += 1;
+        buf[current_idx] = ((self.metadata_params.closure_requested as u8) << 7)
+            | (self.metadata_params.checksum_type as u8);
+        current_idx += 1;
+        current_idx += write_fss_field(
+            self.pdu_header.common_pdu_conf().file_flag,
+            self.metadata_params.file_size,
+            &mut buf[current_idx..],
+        )?;
+        current_idx += self
+            .src_file_name
+            .write_to_be_bytes(&mut buf[current_idx..])?;
+        current_idx += self
+            .dest_file_name
+            .write_to_be_bytes(&mut buf[current_idx..])?;
+        if let Some(opts) = self.options {
+            buf[current_idx..current_idx + opts.len()].copy_from_slice(opts);
+            current_idx += opts.len();
+        }
+        if self.pdu_header.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            current_idx = add_pdu_crc(buf, current_idx);
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes<'longest: 'src_name + 'dest_name + 'opts>(
+        buf: &'longest [u8],
+    ) -> Result<Self, PduError> {
+        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
+        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
+        let is_large_file = pdu_header.pdu_conf.file_flag == LargeFileFlag::Large;
+        // Minimal length: 1 byte + FSS (4 byte) + 2 empty LV (1 byte)
+        let mut min_expected_len = current_idx + 7;
+        if is_large_file {
+            min_expected_len += 4;
+        }
+        generic_length_checks_pdu_deserialization(buf, min_expected_len, full_len_without_crc)?;
+        let directive_type = FileDirectiveType::try_from(buf[current_idx]).map_err(|_| {
+            PduError::InvalidDirectiveType((buf[current_idx], FileDirectiveType::MetadataPdu))
+        })?;
+        if directive_type != FileDirectiveType::MetadataPdu {
+            return Err(PduError::WrongDirectiveType((
+                directive_type,
+                FileDirectiveType::MetadataPdu,
+            )));
+        }
+        current_idx += 1;
+        let (fss_len, file_size) =
+            read_fss_field(pdu_header.pdu_conf.file_flag, &buf[current_idx + 1..]);
+        let metadata_params = MetadataGenericParams {
+            closure_requested: ((buf[current_idx] >> 6) & 0b1) != 0,
+            checksum_type: ChecksumType::try_from(buf[current_idx] & 0b1111)
+                .map_err(|_| PduError::InvalidChecksumType(buf[current_idx] & 0b1111))?,
+            file_size,
+        };
+        current_idx += 1 + fss_len;
+        let src_file_name = Lv::from_bytes(&buf[current_idx..])?;
+        current_idx += src_file_name.len_full();
+        let dest_file_name = Lv::from_bytes(&buf[current_idx..])?;
+        current_idx += dest_file_name.len_full();
+        // All left-over bytes are options.
+        let mut options = None;
+        if current_idx < full_len_without_crc {
+            options = Some(&buf[current_idx..full_len_without_crc]);
+        }
+        Ok(Self {
+            pdu_header,
+            metadata_params,
+            src_file_name,
+            dest_file_name,
+            options,
+        })
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::pdu::metadata::{
+        build_metadata_opts_from_slice, build_metadata_opts_from_vec, MetadataGenericParams,
+        MetadataPdu,
+    };
+    use crate::cfdp::pdu::tests::{common_pdu_conf, verify_raw_header};
+    use crate::cfdp::pdu::{FileDirectiveType, PduHeader};
+    use crate::cfdp::tlv::{Tlv, TlvType};
+    use crate::cfdp::{
+        ChecksumType, CrcFlag, LargeFileFlag, PduType, SegmentMetadataFlag, SegmentationControl,
+    };
+    use std::vec;
+
+    const SRC_FILENAME: &'static str = "hello-world.txt";
+    const DEST_FILENAME: &'static str = "hello-world2.txt";
+
+    fn generic_metadata_pdu<'opts>(
+        crc_flag: CrcFlag,
+        fss: LargeFileFlag,
+        opts: Option<&'opts [u8]>,
+    ) -> (
+        Lv<'static>,
+        Lv<'static>,
+        MetadataPdu<'static, 'static, 'opts>,
+    ) {
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_conf(crc_flag, fss), 0);
+        let metadata_params = MetadataGenericParams::new(false, ChecksumType::Crc32, 0x1010);
+        let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
+        let dest_filename =
+            Lv::new_from_str(DEST_FILENAME).expect("Generating destination LV failed");
+        (
+            src_filename,
+            dest_filename,
+            MetadataPdu::new(
+                pdu_header,
+                metadata_params,
+                src_filename,
+                dest_filename,
+                opts,
+            ),
+        )
+    }
+
+    #[test]
+    fn test_basic() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Normal, None);
+        assert_eq!(
+            metadata_pdu.written_len(),
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        assert_eq!(metadata_pdu.src_file_name(), src_filename);
+        assert_eq!(metadata_pdu.dest_file_name(), dest_filename);
+        assert_eq!(metadata_pdu.options(), None);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Normal, None);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        verify_raw_header(metadata_pdu.pdu_header(), &buf);
+        assert_eq!(buf[7], FileDirectiveType::MetadataPdu as u8);
+        assert_eq!(buf[8] >> 6, false as u8);
+        assert_eq!(buf[8] & 0b1111, ChecksumType::Crc32 as u8);
+        assert_eq!(u32::from_be_bytes(buf[9..13].try_into().unwrap()), 0x1010);
+        let mut current_idx = 13;
+        let src_name_from_raw =
+            Lv::from_bytes(&buf[current_idx..]).expect("Creating source name LV failed");
+        assert_eq!(src_name_from_raw, src_filename);
+        current_idx += src_name_from_raw.len_full();
+        let dest_name_from_raw =
+            Lv::from_bytes(&buf[current_idx..]).expect("Creating dest name LV failed");
+        assert_eq!(dest_name_from_raw, dest_filename);
+        current_idx += dest_name_from_raw.len_full();
+        // No options, so no additional data here.
+        assert_eq!(current_idx, written);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let (_, _, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Normal, None);
+        let mut buf: [u8; 64] = [0; 64];
+        metadata_pdu.write_to_bytes(&mut buf).unwrap();
+        let pdu_read_back = MetadataPdu::from_bytes(&buf);
+        assert!(pdu_read_back.is_ok());
+        let pdu_read_back = pdu_read_back.unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+    }
+
+    #[test]
+    fn test_with_crc_flag() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::WithCrc, LargeFileFlag::Normal, None);
+        let mut buf: [u8; 64] = [0; 64];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + core::mem::size_of::<u32>()
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + 2
+        );
+        let pdu_read_back = MetadataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+    }
+
+    #[test]
+    fn test_with_large_file_flag() {
+        let (src_filename, dest_filename, metadata_pdu) =
+            generic_metadata_pdu(CrcFlag::NoCrc, LargeFileFlag::Large, None);
+        let mut buf: [u8; 64] = [0; 64];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header().header_len()
+                + 1
+                + 1
+                + core::mem::size_of::<u64>()
+                + src_filename.len_full()
+                + dest_filename.len_full()
+        );
+        let pdu_read_back = MetadataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+    }
+
+    #[test]
+    fn test_opts_builders() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_slice = [tlv1, tlv2];
+        let mut buf: [u8; 32] = [0; 32];
+        let opts = build_metadata_opts_from_slice(&mut buf, &tlv_slice);
+        assert!(opts.is_ok());
+        let opts_len = opts.unwrap();
+        assert_eq!(opts_len, tlv1.len_full() + tlv2.len_full());
+        let tlv1_conv_back = Tlv::from_bytes(&buf).unwrap();
+        assert_eq!(tlv1_conv_back, tlv1);
+        let tlv2_conv_back = Tlv::from_bytes(&buf[tlv1_conv_back.len_full()..]).unwrap();
+        assert_eq!(tlv2_conv_back, tlv2);
+    }
+
+    #[test]
+    fn test_opts_builders_from_vec() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_vec = vec![tlv1, tlv2];
+        let mut buf: [u8; 32] = [0; 32];
+        let opts = build_metadata_opts_from_vec(&mut buf, &tlv_vec);
+        assert!(opts.is_ok());
+        let opts_len = opts.unwrap();
+        assert_eq!(opts_len, tlv1.len_full() + tlv2.len_full());
+        let tlv1_conv_back = Tlv::from_bytes(&buf).unwrap();
+        assert_eq!(tlv1_conv_back, tlv1);
+        let tlv2_conv_back = Tlv::from_bytes(&buf[tlv1_conv_back.len_full()..]).unwrap();
+        assert_eq!(tlv2_conv_back, tlv2);
+    }
+
+    #[test]
+    fn test_with_opts() {
+        let tlv1 = Tlv::new_empty(TlvType::FlowLabel);
+        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
+        let tlv2 = Tlv::new(TlvType::MsgToUser, &msg_to_user).unwrap();
+        let tlv_vec = vec![tlv1, tlv2];
+        let mut opts_buf: [u8; 32] = [0; 32];
+        let opts_len = build_metadata_opts_from_vec(&mut opts_buf, &tlv_vec).unwrap();
+        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
+            CrcFlag::NoCrc,
+            LargeFileFlag::Normal,
+            Some(&opts_buf[..opts_len]),
+        );
+        let mut buf: [u8; 128] = [0; 128];
+        let write_res = metadata_pdu.write_to_bytes(&mut buf);
+        assert!(write_res.is_ok());
+        let written = write_res.unwrap();
+        assert_eq!(
+            written,
+            metadata_pdu.pdu_header.header_len()
+                + 1
+                + 1
+                + 4
+                + src_filename.len_full()
+                + dest_filename.len_full()
+                + opts_len
+        );
+        let pdu_read_back = MetadataPdu::from_bytes(&buf).unwrap();
+        assert_eq!(pdu_read_back, metadata_pdu);
+        let opts_iter = pdu_read_back.options_iter();
+        assert!(opts_iter.is_some());
+        let opts_iter = opts_iter.unwrap();
+        let mut accumulated_len = 0;
+        for (idx, opt) in opts_iter.enumerate() {
+            assert_eq!(tlv_vec[idx], opt);
+            accumulated_len += opt.len_full();
+        }
+        assert_eq!(accumulated_len, pdu_read_back.options().unwrap().len());
+    }
+
+    #[test]
+    fn test_corrects_pdu_header() {
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_conf(CrcFlag::NoCrc, LargeFileFlag::Normal),
+            0,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        );
+        let metadata_params = MetadataGenericParams::new(false, ChecksumType::Crc32, 10);
+        let src_filename = Lv::new_from_str(SRC_FILENAME).expect("Generating string LV failed");
+        let dest_filename =
+            Lv::new_from_str(DEST_FILENAME).expect("Generating destination LV failed");
+        let metadata_pdu =
+            MetadataPdu::new_no_opts(pdu_header, metadata_params, src_filename, dest_filename);
+        assert_eq!(metadata_pdu.pdu_header().pdu_type(), PduType::FileDirective);
+    }
+}

src/cfdp/pdu/mod.rs

@@ -0,0 +1,907 @@
+//! CFDP Packet Data Unit (PDU) support.
+use crate::cfdp::*;
+use crate::util::{UnsignedByteField, UnsignedEnum};
+use crate::CRC_CCITT_FALSE;
+use crate::{ByteConversionError, SizeMissmatch};
+use core::fmt::{Display, Formatter};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub mod eof;
+pub mod file_data;
+pub mod finished;
+pub mod metadata;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FileDirectiveType {
+    EofPdu = 0x04,
+    FinishedPdu = 0x05,
+    AckPdu = 0x06,
+    MetadataPdu = 0x07,
+    NakPdu = 0x08,
+    PromptPdu = 0x09,
+    KeepAlivePdu = 0x0c,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum PduError {
+    ByteConversionError(ByteConversionError),
+    /// Found version ID invalid, not equal to [CFDP_VERSION_2].
+    CfdpVersionMissmatch(u8),
+    /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    InvalidEntityLen(u8),
+    /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
+    InvalidTransactionSeqNumLen(u8),
+    /// The first entry will be the source entity ID length, the second one the destination entity
+    /// ID length.
+    SourceDestIdLenMissmatch((usize, usize)),
+    /// The first tuple entry will be the found directive type, the second entry the expected entry
+    /// type.
+    WrongDirectiveType((FileDirectiveType, FileDirectiveType)),
+    /// The directive type field contained a value not in the range of permitted values.
+    /// The first tuple entry will be the found raw number, the second entry the expected entry
+    /// type.
+    InvalidDirectiveType((u8, FileDirectiveType)),
+    /// Invalid condition code. Contains the raw detected value.
+    InvalidConditionCode(u8),
+    /// Invalid checksum type which is not part of the checksums listed in the
+    /// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/).
+    InvalidChecksumType(u8),
+    FileSizeTooLarge(u64),
+    /// If the CRC flag for a PDU is enabled and the checksum check fails. Contains raw 16-bit CRC.
+    ChecksumError(u16),
+    /// Generic error for invalid PDU formats.
+    FormatError,
+    /// Error handling a TLV field.
+    TlvLvError(TlvLvError),
+}
+
+impl Display for PduError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            PduError::InvalidEntityLen(raw_id) => {
+                write!(
+                    f,
+                    "Invalid PDU entity ID length {raw_id}, only [1, 2, 4, 8] are allowed"
+                )
+            }
+            PduError::InvalidTransactionSeqNumLen(raw_id) => {
+                write!(
+                    f,
+                    "invalid PDUtransaction seq num length {raw_id}, only [1, 2, 4, 8] are allowed"
+                )
+            }
+            PduError::CfdpVersionMissmatch(raw) => {
+                write!(
+                    f,
+                    "cfdp version missmatch, found {raw}, expected {CFDP_VERSION_2}"
+                )
+            }
+            PduError::SourceDestIdLenMissmatch((src_len, dest_len)) => {
+                write!(
+                    f,
+                    "missmatch of PDU source length {src_len} and destination length {dest_len}"
+                )
+            }
+            PduError::ByteConversionError(e) => {
+                write!(f, "{}", e)
+            }
+            PduError::FileSizeTooLarge(value) => {
+                write!(f, "file size value {value} exceeds allowed 32 bit width")
+            }
+            PduError::WrongDirectiveType((found, expected)) => {
+                write!(f, "found directive type {found:?}, expected {expected:?}")
+            }
+            PduError::InvalidConditionCode(raw_code) => {
+                write!(f, "found invalid condition code with raw value {raw_code}")
+            }
+            PduError::InvalidDirectiveType((found, expected)) => {
+                write!(
+                    f,
+                    "invalid directive type value {found}, expected {expected:?} ({})",
+                    *expected as u8
+                )
+            }
+            PduError::InvalidChecksumType(checksum_type) => {
+                write!(f, "invalid checksum type {checksum_type}")
+            }
+            PduError::ChecksumError(checksum) => {
+                write!(f, "checksum error for CRC {checksum:#04x}")
+            }
+            PduError::TlvLvError(error) => {
+                write!(f, "pdu tlv error: {error}")
+            }
+            PduError::FormatError => {
+                write!(f, "generic PDU format error")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for PduError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            PduError::ByteConversionError(e) => Some(e),
+            PduError::TlvLvError(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl From<ByteConversionError> for PduError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl From<TlvLvError> for PduError {
+    fn from(e: TlvLvError) -> Self {
+        Self::TlvLvError(e)
+    }
+}
+
+/// Common configuration fields for a PDU.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct CommonPduConfig {
+    source_entity_id: UnsignedByteField,
+    dest_entity_id: UnsignedByteField,
+    pub transaction_seq_num: UnsignedByteField,
+    pub trans_mode: TransmissionMode,
+    pub file_flag: LargeFileFlag,
+    pub crc_flag: CrcFlag,
+    pub direction: Direction,
+}
+
+// TODO: Builder pattern might be applicable here..
+impl CommonPduConfig {
+    pub fn new(
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+        transaction_seq_num: impl Into<UnsignedByteField>,
+        trans_mode: TransmissionMode,
+        file_flag: LargeFileFlag,
+        crc_flag: CrcFlag,
+        direction: Direction,
+    ) -> Result<Self, PduError> {
+        let source_id = source_id.into();
+        let dest_id = dest_id.into();
+        let transaction_seq_num = transaction_seq_num.into();
+        if source_id.size() != dest_id.size() {
+            return Err(PduError::SourceDestIdLenMissmatch((
+                source_id.size(),
+                dest_id.size(),
+            )));
+        }
+        if source_id.size() != 1
+            && source_id.size() != 2
+            && source_id.size() != 4
+            && source_id.size() != 8
+        {
+            return Err(PduError::InvalidEntityLen(source_id.size() as u8));
+        }
+        if transaction_seq_num.size() != 1
+            && transaction_seq_num.size() != 2
+            && transaction_seq_num.size() != 4
+            && transaction_seq_num.size() != 8
+        {
+            return Err(PduError::InvalidTransactionSeqNumLen(
+                transaction_seq_num.size() as u8,
+            ));
+        }
+        Ok(Self {
+            source_entity_id: source_id,
+            dest_entity_id: dest_id,
+            transaction_seq_num,
+            trans_mode,
+            file_flag,
+            crc_flag,
+            direction,
+        })
+    }
+
+    pub fn new_with_defaults(
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+        transaction_seq_num: impl Into<UnsignedByteField>,
+    ) -> Result<Self, PduError> {
+        Self::new(
+            source_id,
+            dest_id,
+            transaction_seq_num,
+            TransmissionMode::Acknowledged,
+            LargeFileFlag::Normal,
+            CrcFlag::NoCrc,
+            Direction::TowardsReceiver,
+        )
+    }
+
+    pub fn source_id(&self) -> UnsignedByteField {
+        self.source_entity_id
+    }
+
+    pub fn dest_id(&self) -> UnsignedByteField {
+        self.dest_entity_id
+    }
+}
+
+pub const FIXED_HEADER_LEN: usize = 4;
+
+/// Abstraction for the PDU header common to all CFDP PDUs.
+///
+/// For detailed information, refer to chapter 5.1 of the CFDP standard.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct PduHeader {
+    pdu_type: PduType,
+    pdu_conf: CommonPduConfig,
+    seg_metadata_flag: SegmentMetadataFlag,
+    seg_ctrl: SegmentationControl,
+    pdu_datafield_len: u16,
+}
+
+impl PduHeader {
+    pub fn new_for_file_data(
+        pdu_conf: CommonPduConfig,
+        pdu_datafield_len: u16,
+        seg_metadata_flag: SegmentMetadataFlag,
+        seg_ctrl: SegmentationControl,
+    ) -> Self {
+        Self::new_generic(
+            PduType::FileData,
+            pdu_conf,
+            pdu_datafield_len,
+            seg_metadata_flag,
+            seg_ctrl,
+        )
+    }
+
+    pub fn new_for_file_data_default(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
+        Self::new_generic(
+            PduType::FileData,
+            pdu_conf,
+            pdu_datafield_len,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        )
+    }
+    pub fn new_no_file_data(pdu_conf: CommonPduConfig, pdu_datafield_len: u16) -> Self {
+        Self::new_generic(
+            PduType::FileDirective,
+            pdu_conf,
+            pdu_datafield_len,
+            SegmentMetadataFlag::NotPresent,
+            SegmentationControl::NoRecordBoundaryPreservation,
+        )
+    }
+
+    pub fn new_generic(
+        pdu_type: PduType,
+        pdu_conf: CommonPduConfig,
+        pdu_datafield_len: u16,
+        seg_metadata_flag: SegmentMetadataFlag,
+        seg_ctrl: SegmentationControl,
+    ) -> Self {
+        Self {
+            pdu_type,
+            pdu_conf,
+            seg_metadata_flag,
+            seg_ctrl,
+            pdu_datafield_len,
+        }
+    }
+
+    /// Returns only the length of the PDU header when written to a raw buffer.
+    pub fn header_len(&self) -> usize {
+        FIXED_HEADER_LEN
+            + self.pdu_conf.source_entity_id.size()
+            + self.pdu_conf.transaction_seq_num.size()
+            + self.pdu_conf.dest_entity_id.size()
+    }
+
+    /// Returns the full length of the PDU when written to a raw buffer, which is the header length
+    /// plus the PDU datafield length.
+    pub fn pdu_len(&self) -> usize {
+        self.header_len() + self.pdu_datafield_len as usize
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
+        // Internal note: There is currently no way to pass a PDU configuration like this, but
+        // this check is still kept for defensive programming.
+        if self.pdu_conf.source_entity_id.size() != self.pdu_conf.dest_entity_id.size() {
+            return Err(PduError::SourceDestIdLenMissmatch((
+                self.pdu_conf.source_entity_id.size(),
+                self.pdu_conf.dest_entity_id.size(),
+            )));
+        }
+        if buf.len()
+            < FIXED_HEADER_LEN
+                + self.pdu_conf.source_entity_id.size()
+                + self.pdu_conf.transaction_seq_num.size()
+        {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: FIXED_HEADER_LEN,
+            })
+            .into());
+        }
+        let mut current_idx = 0;
+        buf[current_idx] = (CFDP_VERSION_2 << 5)
+            | ((self.pdu_type as u8) << 4)
+            | ((self.pdu_conf.direction as u8) << 3)
+            | ((self.pdu_conf.trans_mode as u8) << 2)
+            | ((self.pdu_conf.crc_flag as u8) << 1)
+            | (self.pdu_conf.file_flag as u8);
+        current_idx += 1;
+        buf[current_idx..current_idx + 2].copy_from_slice(&self.pdu_datafield_len.to_be_bytes());
+        current_idx += 2;
+        buf[current_idx] = ((self.seg_ctrl as u8) << 7)
+            | (((self.pdu_conf.source_entity_id.size() - 1) as u8) << 4)
+            | ((self.seg_metadata_flag as u8) << 3)
+            | ((self.pdu_conf.transaction_seq_num.size() - 1) as u8);
+        current_idx += 1;
+        self.pdu_conf.source_entity_id.write_to_be_bytes(
+            &mut buf[current_idx..current_idx + self.pdu_conf.source_entity_id.size()],
+        )?;
+        current_idx += self.pdu_conf.source_entity_id.size();
+        self.pdu_conf.transaction_seq_num.write_to_be_bytes(
+            &mut buf[current_idx..current_idx + self.pdu_conf.transaction_seq_num.size()],
+        )?;
+        current_idx += self.pdu_conf.transaction_seq_num.size();
+        self.pdu_conf.dest_entity_id.write_to_be_bytes(
+            &mut buf[current_idx..current_idx + self.pdu_conf.dest_entity_id.size()],
+        )?;
+        current_idx += self.pdu_conf.dest_entity_id.size();
+        Ok(current_idx)
+    }
+
+    /// This function first verifies that the buffer can hold the full length of the PDU parsed from
+    /// the header. Then, it verifies the checksum as specified in the standard if the CRC flag
+    /// of the PDU header is set.
+    ///
+    /// This function will return the PDU length excluding the 2 CRC bytes on success. If the CRC
+    /// flag is not set, it will simply return the PDU length.
+    pub fn verify_length_and_checksum(&self, buf: &[u8]) -> Result<usize, PduError> {
+        if buf.len() < self.pdu_len() {
+            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: self.pdu_len(),
+            })
+            .into());
+        }
+        if self.pdu_conf.crc_flag == CrcFlag::WithCrc {
+            let mut digest = CRC_CCITT_FALSE.digest();
+            digest.update(&buf[..self.pdu_len()]);
+            if digest.finalize() != 0 {
+                return Err(PduError::ChecksumError(u16::from_be_bytes(
+                    buf[self.pdu_len() - 2..self.pdu_len()].try_into().unwrap(),
+                )));
+            }
+            return Ok(self.pdu_len() - 2);
+        }
+        Ok(self.pdu_len())
+    }
+
+    /// Please note that this function will not verify that the passed buffer can hold the full
+    /// PDU length. This allows recovering the header portion even if the data field length is
+    /// invalid. This function will also not do the CRC procedure specified in chapter 4.1.1
+    /// and 4.1.2 because performing the CRC procedure requires the buffer to be large enough
+    /// to hold the full PDU.
+    ///
+    /// Both functions can however be performed with the [Self::verify_length_and_checksum]
+    /// function.
+    pub fn from_bytes(buf: &[u8]) -> Result<(Self, usize), PduError> {
+        if buf.len() < FIXED_HEADER_LEN {
+            return Err(PduError::ByteConversionError(
+                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                    found: buf.len(),
+                    expected: FIXED_HEADER_LEN,
+                }),
+            ));
+        }
+        let cfdp_version_raw = (buf[0] >> 5) & 0b111;
+        if cfdp_version_raw != CFDP_VERSION_2 {
+            return Err(PduError::CfdpVersionMissmatch(cfdp_version_raw));
+        }
+        // unwrap for single bit fields: This operation will always succeed.
+        let pdu_type = PduType::try_from((buf[0] >> 4) & 0b1).unwrap();
+        let direction = Direction::try_from((buf[0] >> 3) & 0b1).unwrap();
+        let trans_mode = TransmissionMode::try_from((buf[0] >> 2) & 0b1).unwrap();
+        let crc_flag = CrcFlag::try_from((buf[0] >> 1) & 0b1).unwrap();
+        let file_flag = LargeFileFlag::try_from(buf[0] & 0b1).unwrap();
+        let pdu_datafield_len = u16::from_be_bytes(buf[1..3].try_into().unwrap());
+        let seg_ctrl = SegmentationControl::try_from((buf[3] >> 7) & 0b1).unwrap();
+        let expected_len_entity_ids = (((buf[3] >> 4) & 0b111) + 1) as usize;
+        if (expected_len_entity_ids != 1)
+            && (expected_len_entity_ids != 2)
+            && (expected_len_entity_ids != 4)
+            && (expected_len_entity_ids != 8)
+        {
+            return Err(PduError::InvalidEntityLen(expected_len_entity_ids as u8));
+        }
+        let seg_metadata_flag = SegmentMetadataFlag::try_from((buf[3] >> 3) & 0b1).unwrap();
+        let expected_len_seq_num = ((buf[3] & 0b111) + 1) as usize;
+        if (expected_len_seq_num != 1)
+            && (expected_len_seq_num != 2)
+            && (expected_len_seq_num != 4)
+            && (expected_len_seq_num != 8)
+        {
+            return Err(PduError::InvalidTransactionSeqNumLen(
+                expected_len_seq_num as u8,
+            ));
+        }
+        if buf.len() < (4 + 2 * expected_len_entity_ids + expected_len_seq_num) {
+            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: 4 + 2 * expected_len_entity_ids + expected_len_seq_num,
+            })
+            .into());
+        }
+        let mut current_idx = 4;
+        // It is okay to unwrap here because we checked the validity of the expected length and of
+        // the remaining buffer length.
+        let source_id =
+            UnsignedByteField::new_from_be_bytes(expected_len_entity_ids, &buf[current_idx..])
+                .unwrap();
+        current_idx += expected_len_entity_ids;
+        let transaction_seq_num =
+            UnsignedByteField::new_from_be_bytes(expected_len_seq_num, &buf[current_idx..])
+                .unwrap();
+        current_idx += expected_len_seq_num;
+        let dest_id =
+            UnsignedByteField::new_from_be_bytes(expected_len_entity_ids, &buf[current_idx..])
+                .unwrap();
+        current_idx += expected_len_entity_ids;
+        let common_pdu_conf = CommonPduConfig::new(
+            source_id,
+            dest_id,
+            transaction_seq_num,
+            trans_mode,
+            file_flag,
+            crc_flag,
+            direction,
+        )
+        .unwrap();
+        Ok((
+            PduHeader {
+                pdu_type,
+                pdu_conf: common_pdu_conf,
+                seg_metadata_flag,
+                seg_ctrl,
+                pdu_datafield_len,
+            },
+            current_idx,
+        ))
+    }
+    pub fn pdu_type(&self) -> PduType {
+        self.pdu_type
+    }
+
+    pub fn common_pdu_conf(&self) -> &CommonPduConfig {
+        &self.pdu_conf
+    }
+
+    pub fn seg_metadata_flag(&self) -> SegmentMetadataFlag {
+        self.seg_metadata_flag
+    }
+    pub fn seg_ctrl(&self) -> SegmentationControl {
+        self.seg_ctrl
+    }
+}
+
+pub(crate) fn write_fss_field(
+    file_flag: LargeFileFlag,
+    file_size: u64,
+    buf: &mut [u8],
+) -> Result<usize, PduError> {
+    Ok(if file_flag == LargeFileFlag::Large {
+        buf[..core::mem::size_of::<u64>()].copy_from_slice(&file_size.to_be_bytes());
+        core::mem::size_of::<u64>()
+    } else {
+        if file_size > u32::MAX as u64 {
+            return Err(PduError::FileSizeTooLarge(file_size));
+        }
+        buf[..core::mem::size_of::<u32>()].copy_from_slice(&(file_size as u32).to_be_bytes());
+        core::mem::size_of::<u32>()
+    })
+}
+
+pub(crate) fn read_fss_field(file_flag: LargeFileFlag, buf: &[u8]) -> (usize, u64) {
+    if file_flag == LargeFileFlag::Large {
+        (
+            core::mem::size_of::<u64>(),
+            u64::from_be_bytes(buf[..core::mem::size_of::<u64>()].try_into().unwrap()),
+        )
+    } else {
+        (
+            core::mem::size_of::<u32>(),
+            u32::from_be_bytes(buf[..core::mem::size_of::<u32>()].try_into().unwrap()).into(),
+        )
+    }
+}
+
+// This is a generic length check applicable to most PDU deserializations. It first checks whether
+// a given buffer can hold an expected minimum size, and then it checks whether the PDU datafield
+// length is larger than that expected minimum size.
+pub(crate) fn generic_length_checks_pdu_deserialization(
+    buf: &[u8],
+    min_expected_len: usize,
+    full_len_without_crc: usize,
+) -> Result<(), ByteConversionError> {
+    // Buffer too short to hold additional expected minimum datasize.
+    if buf.len() < min_expected_len {
+        return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            found: buf.len(),
+            expected: min_expected_len,
+        }));
+    }
+    // This can happen if the PDU datafield length value is invalid.
+    if full_len_without_crc < min_expected_len {
+        return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            found: full_len_without_crc,
+            expected: min_expected_len,
+        }));
+    }
+    Ok(())
+}
+
+pub(crate) fn add_pdu_crc(buf: &mut [u8], mut current_idx: usize) -> usize {
+    let mut digest = CRC_CCITT_FALSE.digest();
+    digest.update(&buf[..current_idx]);
+    buf[current_idx..current_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+    current_idx += 2;
+    current_idx
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::pdu::{CommonPduConfig, PduError, PduHeader, FIXED_HEADER_LEN};
+    use crate::cfdp::{
+        CrcFlag, Direction, LargeFileFlag, PduType, SegmentMetadataFlag, SegmentationControl,
+        TransmissionMode, CFDP_VERSION_2,
+    };
+    use crate::util::{
+        UbfU8, UnsignedByteField, UnsignedByteFieldU16, UnsignedByteFieldU8, UnsignedEnum,
+    };
+    use crate::ByteConversionError;
+    use std::format;
+
+    pub(crate) fn common_pdu_conf(crc_flag: CrcFlag, fss: LargeFileFlag) -> CommonPduConfig {
+        let src_id = UbfU8::new(5);
+        let dest_id = UbfU8::new(10);
+        let transaction_seq_num = UbfU8::new(20);
+        let mut pdu_conf = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_seq_num)
+            .expect("Generating common PDU config");
+        pdu_conf.crc_flag = crc_flag;
+        pdu_conf.file_flag = fss;
+        pdu_conf
+    }
+
+    pub(crate) fn verify_raw_header(pdu_conf: &PduHeader, buf: &[u8]) {
+        assert_eq!((buf[0] >> 5) & 0b111, CFDP_VERSION_2);
+        // File directive
+        assert_eq!((buf[0] >> 4) & 1, pdu_conf.pdu_type as u8);
+        // Towards receiver
+        assert_eq!((buf[0] >> 3) & 1, pdu_conf.pdu_conf.direction as u8);
+        // Acknowledged
+        assert_eq!((buf[0] >> 2) & 1, pdu_conf.pdu_conf.trans_mode as u8);
+        // No CRC
+        assert_eq!((buf[0] >> 1) & 1, pdu_conf.pdu_conf.crc_flag as u8);
+        // Regular file size
+        assert_eq!(buf[0] & 1, pdu_conf.pdu_conf.file_flag as u8);
+        let pdu_datafield_len = u16::from_be_bytes(buf[1..3].try_into().unwrap());
+        assert_eq!(pdu_datafield_len, pdu_conf.pdu_datafield_len);
+        // No record boundary preservation
+        assert_eq!((buf[3] >> 7) & 1, pdu_conf.seg_ctrl as u8);
+        // Entity ID length raw value is actual number of octets - 1 => 0
+        let entity_id_len = pdu_conf.pdu_conf.source_entity_id.size();
+        assert_eq!((buf[3] >> 4) & 0b111, entity_id_len as u8 - 1);
+        // No segment metadata
+        assert_eq!((buf[3] >> 3) & 0b1, pdu_conf.seg_metadata_flag as u8);
+        // Transaction Sequence ID length raw value is actual number of octets - 1 => 0
+        let seq_num_len = pdu_conf.pdu_conf.transaction_seq_num.size();
+        assert_eq!(buf[3] & 0b111, seq_num_len as u8 - 1);
+        let mut current_idx = 4;
+        let mut byte_field_check = |field_len: usize, ubf: &UnsignedByteField| {
+            match field_len {
+                1 => assert_eq!(buf[current_idx], ubf.value() as u8),
+                2 => assert_eq!(
+                    u16::from_be_bytes(
+                        buf[current_idx..current_idx + field_len]
+                            .try_into()
+                            .unwrap()
+                    ),
+                    ubf.value() as u16
+                ),
+                4 => assert_eq!(
+                    u32::from_be_bytes(
+                        buf[current_idx..current_idx + field_len]
+                            .try_into()
+                            .unwrap()
+                    ),
+                    ubf.value() as u32
+                ),
+                8 => assert_eq!(
+                    u64::from_be_bytes(
+                        buf[current_idx..current_idx + field_len]
+                            .try_into()
+                            .unwrap()
+                    ),
+                    ubf.value() as u64
+                ),
+                _ => panic!("invalid entity ID length"),
+            }
+            current_idx += field_len
+        };
+        byte_field_check(entity_id_len, &pdu_conf.pdu_conf.source_entity_id);
+        byte_field_check(seq_num_len, &pdu_conf.pdu_conf.transaction_seq_num);
+        byte_field_check(entity_id_len, &pdu_conf.pdu_conf.dest_entity_id);
+    }
+
+    #[test]
+    fn test_basic_state() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        assert_eq!(pdu_header.pdu_type(), PduType::FileDirective);
+        let common_conf_ref = pdu_header.common_pdu_conf();
+        assert_eq!(*common_conf_ref, common_pdu_cfg);
+        // These should be 0 and ignored for non-filedata PDUs
+        assert_eq!(
+            pdu_header.seg_metadata_flag(),
+            SegmentMetadataFlag::NotPresent
+        );
+        assert_eq!(
+            pdu_header.seg_ctrl(),
+            SegmentationControl::NoRecordBoundaryPreservation
+        );
+        assert_eq!(pdu_header.pdu_datafield_len, 5);
+        assert_eq!(pdu_header.header_len(), 7);
+    }
+
+    #[test]
+    fn test_serialization_1() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        // 4 byte fixed header plus three bytes src, dest ID and transaction ID
+        assert_eq!(res.unwrap(), 7);
+        verify_raw_header(&pdu_header, &buf);
+    }
+
+    #[test]
+    fn test_deserialization_1() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let deser_res = PduHeader::from_bytes(&buf);
+        assert!(deser_res.is_ok());
+        let (header_read_back, read_size) = deser_res.unwrap();
+        assert_eq!(read_size, 7);
+        assert_eq!(header_read_back, pdu_header);
+    }
+
+    #[test]
+    fn test_serialization_2() {
+        let src_id = UnsignedByteFieldU16::new(0x0001);
+        let dest_id = UnsignedByteFieldU16::new(0x0203);
+        let transaction_id = UnsignedByteFieldU16::new(0x0405);
+        let mut common_pdu_cfg =
+            CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+                .expect("common config creation failed");
+        common_pdu_cfg.crc_flag = CrcFlag::WithCrc;
+        common_pdu_cfg.direction = Direction::TowardsSender;
+        common_pdu_cfg.trans_mode = TransmissionMode::Unacknowledged;
+        common_pdu_cfg.file_flag = LargeFileFlag::Large;
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_cfg,
+            5,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        assert_eq!(pdu_header.header_len(), 10);
+        let mut buf: [u8; 16] = [0; 16];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok(), "{}", format!("Result {res:?} not okay"));
+        // 4 byte fixed header, 6 bytes additional fields
+        assert_eq!(res.unwrap(), 10);
+        verify_raw_header(&pdu_header, &buf);
+    }
+
+    #[test]
+    fn test_deserialization_2() {
+        let src_id = UnsignedByteFieldU16::new(0x0001);
+        let dest_id = UnsignedByteFieldU16::new(0x0203);
+        let transaction_id = UnsignedByteFieldU16::new(0x0405);
+        let mut common_pdu_cfg =
+            CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+                .expect("common config creation failed");
+        common_pdu_cfg.crc_flag = CrcFlag::WithCrc;
+        common_pdu_cfg.direction = Direction::TowardsSender;
+        common_pdu_cfg.trans_mode = TransmissionMode::Unacknowledged;
+        common_pdu_cfg.file_flag = LargeFileFlag::Large;
+        let pdu_header = PduHeader::new_for_file_data(
+            common_pdu_cfg,
+            5,
+            SegmentMetadataFlag::Present,
+            SegmentationControl::WithRecordBoundaryPreservation,
+        );
+        let mut buf: [u8; 16] = [0; 16];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let deser_res = PduHeader::from_bytes(&buf);
+        assert!(deser_res.is_ok());
+        let (header_read_back, read_size) = deser_res.unwrap();
+        assert_eq!(read_size, 10);
+        assert_eq!(header_read_back, pdu_header);
+    }
+
+    #[test]
+    fn test_invalid_raw_version() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        buf[0] &= !0b1110_0000;
+        buf[0] |= (CFDP_VERSION_2 + 1) << 5;
+        let res = PduHeader::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let PduError::CfdpVersionMissmatch(raw_version) = error {
+            assert_eq!(raw_version, CFDP_VERSION_2 + 1);
+        } else {
+            panic!("invalid exception: {}", error);
+        }
+    }
+
+    #[test]
+    fn test_buf_too_small_1() {
+        let buf: [u8; 3] = [0; 3];
+        let res = PduHeader::from_bytes(&buf);
+        assert!(res.is_err());
+        let error = res.unwrap_err();
+        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall(missmatch)) =
+            error
+        {
+            assert_eq!(missmatch.found, 3);
+            assert_eq!(missmatch.expected, FIXED_HEADER_LEN);
+        } else {
+            panic!("invalid exception: {}", error);
+        }
+    }
+
+    #[test]
+    fn test_buf_too_small_2() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let header = PduHeader::from_bytes(&buf[0..6]);
+        assert!(header.is_err());
+        let error = header.unwrap_err();
+        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall(missmatch)) =
+            error
+        {
+            assert_eq!(missmatch.found, 6);
+            assert_eq!(missmatch.expected, 7);
+        }
+    }
+
+    #[test]
+    fn test_invalid_seq_len() {
+        let src_id = UbfU8::new(1);
+        let dest_id = UbfU8::new(2);
+        let transaction_seq_id = UbfU8::new(3);
+        let invalid_byte_field = UnsignedByteField::new(3, 5);
+        let pdu_conf_res = CommonPduConfig::new_with_defaults(src_id, dest_id, invalid_byte_field);
+        assert!(pdu_conf_res.is_err());
+        let error = pdu_conf_res.unwrap_err();
+        if let PduError::InvalidTransactionSeqNumLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("Invalid exception: {}", error)
+        }
+        let pdu_conf_res = CommonPduConfig::new_with_defaults(
+            invalid_byte_field,
+            invalid_byte_field,
+            transaction_seq_id,
+        );
+        assert!(pdu_conf_res.is_err());
+        let error = pdu_conf_res.unwrap_err();
+        if let PduError::InvalidEntityLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("Invalid exception: {}", error)
+        }
+    }
+    #[test]
+    fn test_missmatch_src_dest_id() {
+        let src_id = UnsignedByteField::new(1, 5);
+        let dest_id = UnsignedByteField::new(2, 5);
+        let transaction_seq_id = UbfU8::new(3);
+        let pdu_conf_res = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_seq_id);
+        assert!(pdu_conf_res.is_err());
+        let error = pdu_conf_res.unwrap_err();
+        if let PduError::SourceDestIdLenMissmatch((src_len, dest_len)) = error {
+            assert_eq!(src_len, 1);
+            assert_eq!(dest_len, 2);
+        }
+    }
+
+    #[test]
+    fn test_invalid_raw_src_id_len() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        buf[3] &= !0b0111_0000;
+        // Equivalent to the length of three
+        buf[3] |= 0b10 << 4;
+        let header_res = PduHeader::from_bytes(&buf);
+        assert!(header_res.is_err());
+        let error = header_res.unwrap_err();
+        if let PduError::InvalidEntityLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+
+    #[test]
+    fn test_invalid_transaction_seq_id_len() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+            .expect("common config creation failed");
+        let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
+        let mut buf: [u8; 7] = [0; 7];
+        let res = pdu_header.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        buf[3] &= !0b0000_0111;
+        // Equivalent to the length of three
+        buf[3] |= 0b10;
+        let header_res = PduHeader::from_bytes(&buf);
+        assert!(header_res.is_err());
+        let error = header_res.unwrap_err();
+        if let PduError::InvalidTransactionSeqNumLen(len) = error {
+            assert_eq!(len, 3);
+        } else {
+            panic!("invalid exception {:?}", error)
+        }
+    }
+}

src/cfdp/tlv.rs

@@ -0,0 +1,765 @@
+//! Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
+use crate::cfdp::lv::{
+    generic_len_check_data_serialization, generic_len_check_deserialization, Lv, MIN_LV_LEN,
+};
+use crate::cfdp::TlvLvError;
+use crate::util::{UnsignedByteField, UnsignedByteFieldError, UnsignedEnum};
+use crate::{ByteConversionError, SizeMissmatch};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+
+pub const MIN_TLV_LEN: usize = 2;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum TlvType {
+    FilestoreRequest = 0x00,
+    FilestoreResponse = 0x01,
+    MsgToUser = 0x02,
+    FaultHandler = 0x04,
+    FlowLabel = 0x05,
+    EntityId = 0x06,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum TlvTypeField {
+    Standard(TlvType),
+    Custom(u8),
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+pub enum FilestoreActionCode {
+    CreateFile = 0b0000,
+    DeleteFile = 0b0001,
+    RenameFile = 0b0010,
+    /// This operation appends one file to another. The first specified name will form the first
+    /// part of the new file and the name of the new file. This function can be used to get
+    /// similar functionality to the UNIX cat utility (albeit for only two files).
+    AppendFile = 0b0011,
+    /// This operation replaces the content of the first specified file with the content of
+    /// the secondly specified file.
+    ReplaceFile = 0b0100,
+    CreateDirectory = 0b0101,
+    RemoveDirectory = 0b0110,
+    DenyFile = 0b0111,
+    DenyDirectory = 0b1000,
+}
+
+impl From<u8> for TlvTypeField {
+    fn from(value: u8) -> Self {
+        match TlvType::try_from(value) {
+            Ok(tlv_type) => TlvTypeField::Standard(tlv_type),
+            Err(_) => TlvTypeField::Custom(value),
+        }
+    }
+}
+
+impl From<TlvTypeField> for u8 {
+    fn from(value: TlvTypeField) -> Self {
+        match value {
+            TlvTypeField::Standard(std) => std as u8,
+            TlvTypeField::Custom(custom) => custom,
+        }
+    }
+}
+
+/// Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
+///
+/// # Lifetimes
+///  * `data`: If the TLV is generated from a raw bytestream, this will be the lifetime of
+///    the raw bytestream. If the TLV is generated from a raw slice or a similar data reference,
+///    this will be the lifetime of that data reference.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct Tlv<'data> {
+    tlv_type_field: TlvTypeField,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    lv: Lv<'data>,
+}
+
+impl<'data> Tlv<'data> {
+    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvError> {
+        Ok(Tlv {
+            tlv_type_field: TlvTypeField::Standard(tlv_type),
+            lv: Lv::new(data)?,
+        })
+    }
+
+    /// Creates a TLV with an empty value field.
+    pub fn new_empty(tlv_type: TlvType) -> Tlv<'data> {
+        Tlv {
+            tlv_type_field: TlvTypeField::Standard(tlv_type),
+            lv: Lv::new_empty(),
+        }
+    }
+
+    pub fn tlv_type_field(&self) -> TlvTypeField {
+        self.tlv_type_field
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        generic_len_check_data_serialization(buf, self.len_value(), MIN_TLV_LEN)?;
+        buf[0] = self.tlv_type_field.into();
+        self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
+        Ok(self.len_full())
+    }
+
+    pub fn value(&self) -> Option<&[u8]> {
+        self.lv.value()
+    }
+
+    /// Returns the length of the value part, not including the length byte.
+    pub fn len_value(&self) -> usize {
+        self.lv.len_value()
+    }
+
+    /// Returns the full raw length, including the length byte.
+    pub fn len_full(&self) -> usize {
+        self.lv.len_full() + 1
+    }
+
+    /// Checks whether the value field is empty.
+    pub fn is_empty(&self) -> bool {
+        self.lv.is_empty()
+    }
+
+    /// Creates a TLV give a raw bytestream. Please note that is is not necessary to pass the
+    /// bytestream with the exact size of the expected TLV. This function will take care
+    /// of parsing the length byte, and the length of the parsed TLV can be retrieved using
+    /// [Self::len_full].
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
+        generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
+        Ok(Self {
+            tlv_type_field: TlvTypeField::from(buf[0]),
+            lv: Lv::from_bytes(&buf[MIN_LV_LEN..])?,
+        })
+    }
+}
+
+pub(crate) fn verify_tlv_type(raw_type: u8, expected_tlv_type: TlvType) -> Result<(), TlvLvError> {
+    let tlv_type = TlvType::try_from(raw_type)
+        .map_err(|_| TlvLvError::InvalidTlvTypeField((raw_type, Some(expected_tlv_type as u8))))?;
+    if tlv_type != expected_tlv_type {
+        return Err(TlvLvError::InvalidTlvTypeField((
+            tlv_type as u8,
+            Some(expected_tlv_type as u8),
+        )));
+    }
+    Ok(())
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct EntityIdTlv {
+    entity_id: UnsignedByteField,
+}
+
+impl EntityIdTlv {
+    pub fn new(entity_id: UnsignedByteField) -> Self {
+        Self { entity_id }
+    }
+
+    fn len_check(buf: &[u8]) -> Result<(), ByteConversionError> {
+        if buf.len() < 2 {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: 2,
+            }));
+        }
+        Ok(())
+    }
+
+    pub fn len_value(&self) -> usize {
+        self.entity_id.size()
+    }
+
+    pub fn len_full(&self) -> usize {
+        2 + self.entity_id.size()
+    }
+
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        Self::len_check(buf)?;
+        buf[0] = TlvType::EntityId as u8;
+        buf[1] = self.entity_id.size() as u8;
+        self.entity_id.write_to_be_bytes(&mut buf[2..])
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<Self, TlvLvError> {
+        Self::len_check(buf)?;
+        verify_tlv_type(buf[0], TlvType::EntityId)?;
+        let len = buf[1];
+        if len != 1 && len != 2 && len != 4 && len != 8 {
+            return Err(TlvLvError::InvalidValueLength(len as usize));
+        }
+        // Okay to unwrap here. The checks before make sure that the deserialization never fails
+        let entity_id = UnsignedByteField::new_from_be_bytes(len as usize, &buf[2..]).unwrap();
+        Ok(Self { entity_id })
+    }
+
+    /// Convert to a generic [Tlv], which also erases the programmatic type information.
+    pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv, ByteConversionError> {
+        Self::len_check(buf)?;
+        self.entity_id
+            .write_to_be_bytes(&mut buf[2..2 + self.entity_id.size()])?;
+        Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.size()]).map_err(|e| match e {
+            TlvLvError::ByteConversionError(e) => e,
+            // All other errors are impossible.
+            _ => panic!("unexpected TLV error"),
+        })
+    }
+}
+
+impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
+    type Error = TlvLvError;
+
+    fn try_from(value: Tlv) -> Result<Self, Self::Error> {
+        match value.tlv_type_field {
+            TlvTypeField::Standard(tlv_type) => {
+                if tlv_type != TlvType::EntityId {
+                    return Err(TlvLvError::InvalidTlvTypeField((
+                        tlv_type as u8,
+                        Some(TlvType::EntityId as u8),
+                    )));
+                }
+            }
+            TlvTypeField::Custom(val) => {
+                return Err(TlvLvError::InvalidTlvTypeField((
+                    val,
+                    Some(TlvType::EntityId as u8),
+                )));
+            }
+        }
+        if value.len_value() != 1
+            && value.len_value() != 2
+            && value.len_value() != 4
+            && value.len_value() != 8
+        {
+            return Err(TlvLvError::InvalidValueLength(value.len_value()));
+        }
+        Ok(Self::new(
+            UnsignedByteField::new_from_be_bytes(value.len_value(), value.value().unwrap())
+                .map_err(|e| match e {
+                    UnsignedByteFieldError::ByteConversionError(e) => e,
+                    // This can not happen, we checked for the length validity, and the data is always smaller than
+                    // 255 bytes.
+                    _ => panic!("unexpected error"),
+                })?,
+        ))
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct FilestoreRequestTlv<'first_name, 'second_name> {
+    action_code: FilestoreActionCode,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    first_name: Lv<'first_name>,
+    #[cfg_attr(feature = "serde", serde(borrow))]
+    second_name: Option<Lv<'second_name>>,
+}
+
+impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
+    pub fn new_create_file(first_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::CreateFile, first_name, None)
+    }
+
+    pub fn new_delete_file(first_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::DeleteFile, first_name, None)
+    }
+
+    pub fn new_rename_file(
+        source_name: Lv<'first_name>,
+        target_name: Lv<'second_name>,
+    ) -> Result<Self, TlvLvError> {
+        Self::new(
+            FilestoreActionCode::RenameFile,
+            source_name,
+            Some(target_name),
+        )
+    }
+
+    /// This operation appends one file to another. The first specified name will form the first
+    /// part of the new file and the name of the new file. This function can be used to get
+    /// similar functionality to the UNIX cat utility (albeit for only two files).
+    pub fn new_append_file(
+        first_file: Lv<'first_name>,
+        second_file: Lv<'second_name>,
+    ) -> Result<Self, TlvLvError> {
+        Self::new(
+            FilestoreActionCode::AppendFile,
+            first_file,
+            Some(second_file),
+        )
+    }
+
+    /// This operation replaces the content of the first specified file with the content of
+    /// the secondly specified file. This function can be used to get similar functionality to
+    /// the UNIX copy (cp) utility if the target file already exists.
+    pub fn new_replace_file(
+        replaced_file: Lv<'first_name>,
+        new_file: Lv<'second_name>,
+    ) -> Result<Self, TlvLvError> {
+        Self::new(
+            FilestoreActionCode::ReplaceFile,
+            replaced_file,
+            Some(new_file),
+        )
+    }
+
+    pub fn new_create_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::CreateDirectory, dir_name, None)
+    }
+
+    pub fn new_remove_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::RemoveDirectory, dir_name, None)
+    }
+
+    pub fn new_deny_file(file_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::DenyFile, file_name, None)
+    }
+
+    pub fn new_deny_directory(dir_name: Lv<'first_name>) -> Result<Self, TlvLvError> {
+        Self::new(FilestoreActionCode::DenyDirectory, dir_name, None)
+    }
+
+    /// This function will return [None] if the respective action code requires two names but
+    /// only one is passed. It will also returns [None] if the cumulative length of the first
+    /// name and the second name exceeds 255 bytes.
+    ///
+    /// This is the case for the rename, append and replace filestore request.
+    pub fn new(
+        action_code: FilestoreActionCode,
+        first_name: Lv<'first_name>,
+        second_name: Option<Lv<'second_name>>,
+    ) -> Result<Self, TlvLvError> {
+        let mut base_value_len = first_name.len_full();
+        if Self::has_second_filename(action_code) {
+            if second_name.is_none() {
+                return Err(TlvLvError::SecondNameMissing);
+            }
+            base_value_len += second_name.as_ref().unwrap().len_full();
+        }
+        if base_value_len > u8::MAX as usize {
+            return Err(TlvLvError::InvalidValueLength(base_value_len));
+        }
+        Ok(Self {
+            action_code,
+            first_name,
+            second_name,
+        })
+    }
+
+    pub fn has_second_filename(action_code: FilestoreActionCode) -> bool {
+        if action_code == FilestoreActionCode::RenameFile
+            || action_code == FilestoreActionCode::AppendFile
+            || action_code == FilestoreActionCode::ReplaceFile
+        {
+            return true;
+        }
+        false
+    }
+
+    pub fn action_code(&self) -> FilestoreActionCode {
+        self.action_code
+    }
+
+    pub fn first_name(&self) -> Lv<'first_name> {
+        self.first_name
+    }
+
+    pub fn second_name(&self) -> Option<Lv<'second_name>> {
+        self.second_name
+    }
+
+    pub fn len_value(&self) -> usize {
+        let mut len = 1 + self.first_name.len_full();
+        if let Some(second_name) = self.second_name {
+            len += second_name.len_full();
+        }
+        len
+    }
+
+    pub fn len_full(&self) -> usize {
+        2 + self.len_value()
+    }
+
+    pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.len_full() {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: self.len_full(),
+            }));
+        }
+        buf[0] = TlvType::FilestoreRequest as u8;
+        buf[1] = self.len_value() as u8;
+        buf[2] = (self.action_code as u8) << 4;
+        let mut current_idx = 3;
+        // Length checks were already performed.
+        self.first_name.write_to_be_bytes_no_len_check(
+            &mut buf[current_idx..current_idx + self.first_name.len_full()],
+        );
+        current_idx += self.first_name.len_full();
+        if let Some(second_name) = self.second_name {
+            second_name.write_to_be_bytes_no_len_check(
+                &mut buf[current_idx..current_idx + second_name.len_full()],
+            );
+            current_idx += second_name.len_full();
+        }
+        Ok(current_idx)
+    }
+
+    pub fn from_bytes<'longest: 'first_name + 'second_name>(
+        buf: &'longest [u8],
+    ) -> Result<Self, TlvLvError> {
+        if buf.len() < 2 {
+            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: 2,
+            })
+            .into());
+        }
+        verify_tlv_type(buf[0], TlvType::FilestoreRequest)?;
+        let len = buf[1] as usize;
+        let mut current_idx = 2;
+        let action_code = FilestoreActionCode::try_from((buf[2] >> 4) & 0b1111)
+            .map_err(|_| TlvLvError::InvalidFilestoreActionCode((buf[2] >> 4) & 0b1111))?;
+        current_idx += 1;
+        let first_name = Lv::from_bytes(&buf[current_idx..])?;
+        let mut second_name = None;
+
+        current_idx += first_name.len_full();
+        if Self::has_second_filename(action_code) {
+            if current_idx >= 2 + len {
+                return Err(TlvLvError::SecondNameMissing);
+            }
+            second_name = Some(Lv::from_bytes(&buf[current_idx..])?);
+        }
+        Ok(Self {
+            action_code,
+            first_name,
+            second_name,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::cfdp::lv::Lv;
+    use crate::cfdp::tlv::{FilestoreActionCode, FilestoreRequestTlv, Tlv, TlvType, TlvTypeField};
+    use crate::cfdp::TlvLvError;
+    use crate::util::{UbfU8, UnsignedEnum};
+
+    const TLV_TEST_STR_0: &'static str = "hello.txt";
+    const TLV_TEST_STR_1: &'static str = "hello2.txt";
+
+    #[test]
+    fn test_basic() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
+        assert!(tlv_res.is_ok());
+        let tlv_res = tlv_res.unwrap();
+        assert_eq!(
+            tlv_res.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::EntityId)
+        );
+        assert_eq!(tlv_res.len_full(), 3);
+        assert_eq!(tlv_res.len_value(), 1);
+        assert!(!tlv_res.is_empty());
+        assert!(tlv_res.value().is_some());
+        assert_eq!(tlv_res.value().unwrap()[0], 5);
+    }
+
+    #[test]
+    fn test_serialization() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
+        let tlv_res = Tlv::new(TlvType::EntityId, &buf[0..1]);
+        assert!(tlv_res.is_ok());
+        let tlv_res = tlv_res.unwrap();
+        let mut ser_buf: [u8; 4] = [0; 4];
+        assert!(tlv_res.write_to_bytes(&mut ser_buf).is_ok());
+        assert_eq!(ser_buf[0], TlvType::EntityId as u8);
+        assert_eq!(ser_buf[1], 1);
+        assert_eq!(ser_buf[2], 5);
+    }
+
+    #[test]
+    fn test_deserialization() {
+        let entity_id = UbfU8::new(5);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(entity_id.write_to_be_bytes(&mut buf[2..]).is_ok());
+        buf[0] = TlvType::EntityId as u8;
+        buf[1] = 1;
+        let tlv_from_raw = Tlv::from_bytes(&mut buf);
+        assert!(tlv_from_raw.is_ok());
+        let tlv_from_raw = tlv_from_raw.unwrap();
+        assert_eq!(
+            tlv_from_raw.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::EntityId)
+        );
+        assert_eq!(tlv_from_raw.len_value(), 1);
+        assert_eq!(tlv_from_raw.len_full(), 3);
+        assert!(tlv_from_raw.value().is_some());
+        assert_eq!(tlv_from_raw.value().unwrap()[0], 5);
+    }
+
+    #[test]
+    fn test_empty() {
+        let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
+        assert!(tlv_empty.value().is_none());
+        assert!(tlv_empty.is_empty());
+        assert_eq!(tlv_empty.len_full(), 2);
+        assert_eq!(tlv_empty.len_value(), 0);
+        assert_eq!(
+            tlv_empty.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+    }
+
+    #[test]
+    fn test_empty_serialization() {
+        let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
+        let mut buf: [u8; 4] = [0; 4];
+        assert!(tlv_empty.write_to_bytes(&mut buf).is_ok());
+        assert_eq!(buf[0], TlvType::MsgToUser as u8);
+        assert_eq!(buf[1], 0);
+    }
+
+    #[test]
+    fn test_empty_deserialization() {
+        let mut buf: [u8; 4] = [0; 4];
+        buf[0] = TlvType::MsgToUser as u8;
+        buf[1] = 0;
+        let tlv_empty = Tlv::from_bytes(&mut buf);
+        assert!(tlv_empty.is_ok());
+        let tlv_empty = tlv_empty.unwrap();
+        assert!(tlv_empty.is_empty());
+        assert!(tlv_empty.value().is_none());
+        assert_eq!(
+            tlv_empty.tlv_type_field(),
+            TlvTypeField::Standard(TlvType::MsgToUser)
+        );
+        assert_eq!(tlv_empty.len_full(), 2);
+        assert_eq!(tlv_empty.len_value(), 0);
+    }
+
+    #[test]
+    fn test_buf_too_large() {
+        let buf_too_large: [u8; u8::MAX as usize + 1] = [0; u8::MAX as usize + 1];
+        let tlv_res = Tlv::new(TlvType::MsgToUser, &buf_too_large);
+        assert!(tlv_res.is_err());
+        let error = tlv_res.unwrap_err();
+        if let TlvLvError::DataTooLarge(size) = error {
+            assert_eq!(size, u8::MAX as usize + 1);
+        } else {
+            panic!("unexpected error {:?}", error);
+        }
+    }
+
+    #[test]
+    fn test_deserialization_custom_tlv_type() {
+        let mut buf: [u8; 4] = [0; 4];
+        buf[0] = 3;
+        buf[1] = 1;
+        buf[2] = 5;
+        let tlv = Tlv::from_bytes(&mut buf);
+        assert!(tlv.is_ok());
+        let tlv = tlv.unwrap();
+        assert_eq!(tlv.tlv_type_field(), TlvTypeField::Custom(3));
+        assert_eq!(tlv.len_value(), 1);
+        assert_eq!(tlv.len_full(), 3);
+    }
+
+    fn generic_fs_request_test_one_file(
+        action_code: FilestoreActionCode,
+    ) -> FilestoreRequestTlv<'static, 'static> {
+        assert!(!FilestoreRequestTlv::has_second_filename(action_code));
+        let first_name = Lv::new_from_str(TLV_TEST_STR_0).unwrap();
+        let fs_request = match action_code {
+            FilestoreActionCode::CreateFile => FilestoreRequestTlv::new_create_file(first_name),
+            FilestoreActionCode::DeleteFile => FilestoreRequestTlv::new_delete_file(first_name),
+            FilestoreActionCode::CreateDirectory => {
+                FilestoreRequestTlv::new_create_directory(first_name)
+            }
+            FilestoreActionCode::RemoveDirectory => {
+                FilestoreRequestTlv::new_remove_directory(first_name)
+            }
+            FilestoreActionCode::DenyFile => FilestoreRequestTlv::new_deny_file(first_name),
+            FilestoreActionCode::DenyDirectory => {
+                FilestoreRequestTlv::new_deny_directory(first_name)
+            }
+            _ => panic!("invalid action code"),
+        };
+        assert!(fs_request.is_ok());
+        let fs_request = fs_request.unwrap();
+        assert_eq!(fs_request.len_value(), 1 + first_name.len_full());
+        assert_eq!(fs_request.len_full(), fs_request.len_value() + 2);
+        assert_eq!(fs_request.action_code(), action_code);
+        assert_eq!(fs_request.first_name(), first_name);
+        assert_eq!(fs_request.second_name(), None);
+        fs_request
+    }
+
+    fn generic_fs_request_test_two_files(
+        action_code: FilestoreActionCode,
+    ) -> FilestoreRequestTlv<'static, 'static> {
+        assert!(FilestoreRequestTlv::has_second_filename(action_code));
+        let first_name = Lv::new_from_str(TLV_TEST_STR_0).unwrap();
+        let second_name = Lv::new_from_str(TLV_TEST_STR_1).unwrap();
+        let fs_request = match action_code {
+            FilestoreActionCode::ReplaceFile => {
+                FilestoreRequestTlv::new_replace_file(first_name, second_name)
+            }
+            FilestoreActionCode::AppendFile => {
+                FilestoreRequestTlv::new_append_file(first_name, second_name)
+            }
+            FilestoreActionCode::RenameFile => {
+                FilestoreRequestTlv::new_rename_file(first_name, second_name)
+            }
+            _ => panic!("invalid action code"),
+        };
+        assert!(fs_request.is_ok());
+        let fs_request = fs_request.unwrap();
+        assert_eq!(
+            fs_request.len_value(),
+            1 + first_name.len_full() + second_name.len_full()
+        );
+        assert_eq!(fs_request.len_full(), fs_request.len_value() + 2);
+        assert_eq!(fs_request.action_code(), action_code);
+        assert_eq!(fs_request.first_name(), first_name);
+        assert!(fs_request.second_name().is_some());
+        assert_eq!(fs_request.second_name().unwrap(), second_name);
+        fs_request
+    }
+
+    #[test]
+    fn test_fs_request_basic_create_file() {
+        generic_fs_request_test_one_file(FilestoreActionCode::CreateFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_delete() {
+        generic_fs_request_test_one_file(FilestoreActionCode::DeleteFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_create_dir() {
+        generic_fs_request_test_one_file(FilestoreActionCode::CreateDirectory);
+    }
+
+    #[test]
+    fn test_fs_request_basic_remove_dir() {
+        generic_fs_request_test_one_file(FilestoreActionCode::RemoveDirectory);
+    }
+
+    #[test]
+    fn test_fs_request_basic_deny_file() {
+        generic_fs_request_test_one_file(FilestoreActionCode::DenyFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_deny_dir() {
+        generic_fs_request_test_one_file(FilestoreActionCode::DenyDirectory);
+    }
+
+    #[test]
+    fn test_fs_request_basic_append_file() {
+        generic_fs_request_test_two_files(FilestoreActionCode::AppendFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_rename_file() {
+        generic_fs_request_test_two_files(FilestoreActionCode::RenameFile);
+    }
+
+    #[test]
+    fn test_fs_request_basic_replace_file() {
+        generic_fs_request_test_two_files(FilestoreActionCode::ReplaceFile);
+    }
+
+    fn check_fs_request_first_part(
+        buf: &[u8],
+        action_code: FilestoreActionCode,
+        expected_val_len: u8,
+    ) -> usize {
+        assert_eq!(buf[0], TlvType::FilestoreRequest as u8);
+        assert_eq!(buf[1], expected_val_len);
+        assert_eq!((buf[2] >> 4) & 0b1111, action_code as u8);
+        let lv = Lv::from_bytes(&buf[3..]);
+        assert!(lv.is_ok());
+        let lv = lv.unwrap();
+        assert_eq!(lv.value_as_str().unwrap().unwrap(), TLV_TEST_STR_0);
+        3 + lv.len_full()
+    }
+
+    #[test]
+    fn test_fs_request_serialization_one_file() {
+        let req = generic_fs_request_test_one_file(FilestoreActionCode::CreateFile);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = req.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, 3 + 1 + TLV_TEST_STR_0.len());
+        assert_eq!(written, req.len_full());
+        check_fs_request_first_part(
+            &buf,
+            FilestoreActionCode::CreateFile,
+            1 + 1 + TLV_TEST_STR_0.len() as u8,
+        );
+    }
+
+    #[test]
+    fn test_fs_request_deserialization_one_file() {
+        let req = generic_fs_request_test_one_file(FilestoreActionCode::CreateFile);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = req.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let req_conv_back = FilestoreRequestTlv::from_bytes(&buf);
+        assert!(req_conv_back.is_ok());
+        let req_conv_back = req_conv_back.unwrap();
+        assert_eq!(req_conv_back, req);
+    }
+
+    #[test]
+    fn test_fs_request_serialization_two_files() {
+        let req = generic_fs_request_test_two_files(FilestoreActionCode::RenameFile);
+        let mut buf: [u8; 64] = [0; 64];
+        let res = req.write_to_bytes(&mut buf);
+        assert!(res.is_ok());
+        let written = res.unwrap();
+        assert_eq!(written, req.len_full());
+        assert_eq!(
+            written,
+            3 + 1 + TLV_TEST_STR_0.len() + 1 + TLV_TEST_STR_1.len()
+        );
+        let current_idx = check_fs_request_first_part(
+            &buf,
+            FilestoreActionCode::RenameFile,
+            1 + 1 + TLV_TEST_STR_0.len() as u8 + 1 + TLV_TEST_STR_1.len() as u8,
+        );
+        let second_lv = Lv::from_bytes(&buf[current_idx..]);
+        assert!(second_lv.is_ok());
+        let second_lv = second_lv.unwrap();
+        assert_eq!(second_lv.value_as_str().unwrap().unwrap(), TLV_TEST_STR_1);
+        assert_eq!(current_idx + second_lv.len_full(), req.len_full());
+    }
+
+    #[test]
+    fn test_fs_request_deserialization_two_files() {
+        let req = generic_fs_request_test_two_files(FilestoreActionCode::RenameFile);
+        let mut buf: [u8; 64] = [0; 64];
+        req.write_to_bytes(&mut buf).unwrap();
+        let req_conv_back = FilestoreRequestTlv::from_bytes(&buf);
+        assert!(req_conv_back.is_ok());
+        let req_conv_back = req_conv_back.unwrap();
+        assert_eq!(req_conv_back, req);
+    }
+}

src/ecss/event.rs

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

src/ecss/hk.rs

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

src/ecss/mod.rs

@@ -1,33 +1,70 @@
 //! Common definitions and helpers required to create PUS TMTC packets according to
 //! [ECSS-E-ST-70-41C](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/)
-use crate::{ByteConversionError, CcsdsPacket, SizeMissmatch};
+//!
+//! You can find the PUS telecommand definitions in the [crate::tc] module and ithe PUS telemetry definitions
+//! inside the [crate::tm] module.
+use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
 use core::fmt::{Debug, Display, Formatter};
 use core::mem::size_of;
-use crc::{Crc, CRC_16_IBM_3740};
+use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 #[cfg(feature = "std")]
 use std::error::Error;
 
-pub type CrcType = u16;
+pub mod event;
+pub mod hk;
+pub mod scheduling;
+pub mod verification;
 
-/// CRC algorithm used by the PUS standard.
-pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
+pub type CrcType = u16;
 pub const CCSDS_HEADER_LEN: usize = size_of::<crate::zc::SpHeader>();
 
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[derive(Debug, Copy, Clone, Eq, PartialEq, IntoPrimitive, TryFromPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[repr(u8)]
+#[non_exhaustive]
 pub enum PusServiceId {
     /// Service 1
     Verification = 1,
+    /// Service 2
+    DeviceAccess = 2,
     /// Service 3
     Housekeeping = 3,
+    /// Service 4
+    ParameterStatistics = 4,
     /// Service 5
     Event = 5,
+    /// Service 6
+    MemoryManagement = 6,
     /// Service 8
     Action = 8,
+    /// Service 9
+    TimeManagement = 9,
+    /// Service 11
+    Scheduling = 11,
+    /// Service 12
+    OnBoardMonitoring = 12,
+    /// Service 13
+    LargePacketTransfer = 13,
+    /// Service 14
+    RealTimeForwardingControl = 14,
+    /// Service 15
+    StorageAndRetrival = 15,
     /// Service 17
     Test = 17,
+    /// Service 18
+    OpsAndProcedures = 18,
+    /// Service 19
+    EventAction = 19,
+    /// Service 20
+    Parameter = 20,
+    /// Service 21
+    RequestSequencing = 21,
+    /// Service 22
+    PositionBasedScheduling = 22,
+    /// Service 23
+    FileManagement = 23,
 }
 
 /// All PUS versions. Only PUS C is supported by this library.
@@ -119,16 +156,15 @@ impl Display for PusError {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         match self {
             PusError::VersionNotSupported(v) => {
-                write!(f, "PUS version {:?} not supported", v)
+                write!(f, "PUS version {v:?} not supported")
             }
             PusError::IncorrectCrc(crc) => {
-                write!(f, "crc16 {:#04x} is incorrect", crc)
+                write!(f, "crc16 {crc:#04x} is incorrect")
             }
             PusError::RawDataTooShort(size) => {
                 write!(
                     f,
-                    "deserialization error, provided raw data with size {} too short",
-                    size
+                    "deserialization error, provided raw data with size {size} too short"
                 )
             }
             PusError::NoRawData => {
@@ -138,7 +174,7 @@ impl Display for PusError {
                 write!(f, "crc16 was not calculated")
             }
             PusError::ByteConversionError(e) => {
-                write!(f, "low level byte conversion error: {}", e)
+                write!(f, "low level byte conversion error: {e}")
             }
         }
     }
@@ -221,13 +257,22 @@ pub(crate) fn user_data_from_raw(
     }
 }
 
-pub(crate) fn verify_crc16_from_raw(raw_data: &[u8], crc16: u16) -> Result<(), PusError> {
+pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
+    raw_data: &[u8],
+    crc16: u16,
+) -> Result<(), PusError> {
+    verify_crc16_ccitt_false_from_raw(raw_data)
+        .then(|| ())
+        .ok_or(PusError::IncorrectCrc(crc16))
+}
+
+pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
     let mut digest = CRC_CCITT_FALSE.digest();
     digest.update(raw_data);
     if digest.finalize() == 0 {
-        return Ok(());
+        return true;
     }
-    Err(PusError::IncorrectCrc(crc16))
+    false
 }
 
 macro_rules! ccsds_impl {
@@ -251,6 +296,7 @@ macro_rules! sp_header_impls {
     }
 }
 
+use crate::util::{GenericUnsignedByteField, ToBeBytes, UnsignedEnum};
 pub(crate) use ccsds_impl;
 pub(crate) use sp_header_impls;
 
@@ -258,66 +304,17 @@ pub(crate) use sp_header_impls;
 /// and an unsigned value. The trait makes no assumptions about the actual type of the unsigned
 /// value and only requires implementors to implement a function which writes the enumeration into
 /// a raw byte format.
-pub trait EcssEnumeration {
+pub trait EcssEnumeration: UnsignedEnum {
     /// Packet Format Code, which denotes the number of bits of the enumeration
     fn pfc(&self) -> u8;
-    fn byte_width(&self) -> usize {
-        (self.pfc() / 8) as usize
-    }
-    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError>;
 }
 
 pub trait EcssEnumerationExt: EcssEnumeration + Debug + Copy + Clone + PartialEq + Eq {}
 
-pub trait ToBeBytes {
-    type ByteArray: AsRef<[u8]>;
-    fn to_be_bytes(&self) -> Self::ByteArray;
-}
-
-impl ToBeBytes for () {
-    type ByteArray = [u8; 0];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        []
-    }
-}
-
-impl ToBeBytes for u8 {
-    type ByteArray = [u8; 1];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u8::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u16 {
-    type ByteArray = [u8; 2];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u16::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u32 {
-    type ByteArray = [u8; 4];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u32::to_be_bytes(*self)
-    }
-}
-
-impl ToBeBytes for u64 {
-    type ByteArray = [u8; 8];
-
-    fn to_be_bytes(&self) -> Self::ByteArray {
-        u64::to_be_bytes(*self)
-    }
-}
-
 #[derive(Debug, Copy, Clone, Eq, PartialEq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct GenericEcssEnumWrapper<TYPE> {
-    val: TYPE,
+    field: GenericUnsignedByteField<TYPE>,
 }
 
 impl<TYPE> GenericEcssEnumWrapper<TYPE> {
@@ -326,7 +323,19 @@ impl<TYPE> GenericEcssEnumWrapper<TYPE> {
     }
 
     pub fn new(val: TYPE) -> Self {
-        Self { val }
+        Self {
+            field: GenericUnsignedByteField::new(val),
+        }
+    }
+}
+
+impl<TYPE: ToBeBytes> UnsignedEnum for GenericEcssEnumWrapper<TYPE> {
+    fn size(&self) -> usize {
+        (self.pfc() / 8) as usize
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        self.field.write_to_be_bytes(buf)
     }
 }
 
@@ -334,17 +343,6 @@ impl<TYPE: ToBeBytes> EcssEnumeration for GenericEcssEnumWrapper<TYPE> {
     fn pfc(&self) -> u8 {
         size_of::<TYPE>() as u8 * 8_u8
     }
-
-    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<(), ByteConversionError> {
-        if buf.len() < self.byte_width() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: buf.len(),
-                expected: self.byte_width(),
-            }));
-        }
-        buf[0..self.byte_width()].copy_from_slice(self.val.to_be_bytes().as_ref());
-        Ok(())
-    }
 }
 
 impl<TYPE: Debug + Copy + Clone + PartialEq + Eq + ToBeBytes> EcssEnumerationExt
@@ -357,9 +355,17 @@ pub type EcssEnumU16 = GenericEcssEnumWrapper<u16>;
 pub type EcssEnumU32 = GenericEcssEnumWrapper<u32>;
 pub type EcssEnumU64 = GenericEcssEnumWrapper<u64>;
 
+/// Generic trait for PUS packet abstractions which can written to a raw slice as their raw
+/// byte representation. This is especially useful for generic abstractions which depend only
+/// on the serialization of those packets.
+pub trait SerializablePusPacket {
+    fn len_packed(&self) -> usize;
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError>;
+}
+
 #[cfg(test)]
 mod tests {
-    use crate::ecss::{EcssEnumU16, EcssEnumU32, EcssEnumU8, EcssEnumeration};
+    use crate::ecss::{EcssEnumU16, EcssEnumU32, EcssEnumU8, UnsignedEnum};
     use crate::ByteConversionError;
 
     #[test]

src/ecss/scheduling.rs

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

src/ecss/verification.rs

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

src/lib.rs

@@ -7,13 +7,15 @@
 //!
 //!  - Space Packet implementation according to
 //!    [CCSDS Blue Book 133.0-B-2](https://public.ccsds.org/Pubs/133x0b2e1.pdf)
+//!  - CCSDS File Delivery Protocol (CFDP) packet implementations according to
+//!    [CCSDS Blue Book 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf)
 //!  - PUS Telecommand and PUS Telemetry implementation according to the
 //!    [ECSS-E-ST-70-41C standard](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
 //!  - CUC (CCSDS Unsegmented Time Code) implementation according to
 //!    [CCSDS 301.0-B-4 3.2](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 //!  - CDS (CCSDS Day Segmented Time Code) implementation according to
 //!    [CCSDS 301.0-B-4 3.3](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
-//!  - Some helper types to support ASCII timecodes ad specified in
+//!  - Some helper types to support ASCII timecodes as specified in
 //!    [CCSDS 301.0-B-4 3.5](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 //!
 //! ## Features
@@ -60,23 +62,31 @@ extern crate alloc;
 extern crate std;
 
 use crate::ecss::CCSDS_HEADER_LEN;
-use core::fmt::{Display, Formatter};
+use core::fmt::{Debug, Display, Formatter};
+use crc::{Crc, CRC_16_IBM_3740};
 use delegate::delegate;
+#[cfg(not(feature = "std"))]
+use num_traits::Unsigned;
 #[cfg(feature = "std")]
 use std::error::Error;
 
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+pub mod cfdp;
 pub mod ecss;
 pub mod tc;
 pub mod time;
 pub mod tm;
+pub mod util;
 
 mod private {
     pub trait Sealed {}
 }
 
+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard.
+pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
+
 pub const MAX_APID: u16 = 2u16.pow(11) - 1;
 pub const MAX_SEQ_COUNT: u16 = 2u16.pow(14) - 1;
 

src/tc.rs

@@ -6,7 +6,7 @@
 //! ```rust
 //! use spacepackets::{CcsdsPacket, SpHeader};
 //! use spacepackets::tc::{PusTc, PusTcSecondaryHeader};
-//! use spacepackets::ecss::PusPacket;
+//! use spacepackets::ecss::{PusPacket, SerializablePusPacket};
 //!
 //! // Create a ping telecommand with no user application data
 //! let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
@@ -33,12 +33,13 @@
 //! ```
 use crate::ecss::{
     ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
-    verify_crc16_from_raw, CrcType, PusError, PusPacket, PusVersion, CRC_CCITT_FALSE,
+    verify_crc16_ccitt_false_from_raw_to_pus_error, CrcType, PusError, PusPacket, PusVersion,
+    SerializablePusPacket,
 };
-use crate::SpHeader;
 use crate::{
     ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SizeMissmatch, CCSDS_HEADER_LEN,
 };
+use crate::{SpHeader, CRC_CCITT_FALSE};
 use core::mem::size_of;
 use delegate::delegate;
 #[cfg(feature = "serde")]
@@ -205,29 +206,35 @@ impl PusTcSecondaryHeader {
     }
 }
 
-/// This class models a PUS telecommand. It is the primary data structure to generate the raw byte
-/// representation of a PUS telecommand or to deserialize from one from raw bytes.
+/// This class models the PUS C telecommand packet. It is the primary data structure to generate the
+/// raw byte representation of a PUS telecommand or to deserialize from one from raw bytes.
 ///
 /// This class also derives the [serde::Serialize] and [serde::Deserialize] trait if the
 /// [serde] feature is used, which allows to send around TC packets in a raw byte format using a
 /// serde provider like [postcard](https://docs.rs/postcard/latest/postcard/).
 ///
 /// There is no spare bytes support yet.
-#[derive(PartialEq, Eq, Copy, Clone, Debug)]
+///
+/// # Lifetimes
+///
+/// * `'raw_data` - If the TC is not constructed from a raw slice, this will be the life time of
+///    a buffer where the user provided application data will be serialized into. If it
+///    is, this is the lifetime of the raw byte slice it is constructed from.
+#[derive(Eq, Copy, Clone, Debug)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct PusTc<'app_data> {
+pub struct PusTc<'raw_data> {
     sp_header: SpHeader,
     pub sec_header: PusTcSecondaryHeader,
     /// If this is set to false, a manual call to [PusTc::calc_own_crc16] or
     /// [PusTc::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
     pub calc_crc_on_serialization: bool,
     #[cfg_attr(feature = "serde", serde(skip))]
-    raw_data: Option<&'app_data [u8]>,
-    app_data: Option<&'app_data [u8]>,
+    raw_data: Option<&'raw_data [u8]>,
+    app_data: Option<&'raw_data [u8]>,
     crc16: Option<u16>,
 }
 
-impl<'app_data> PusTc<'app_data> {
+impl<'raw_data> PusTc<'raw_data> {
     /// Generates a new struct instance.
     ///
     /// # Arguments
@@ -243,7 +250,7 @@ impl<'app_data> PusTc<'app_data> {
     pub fn new(
         sp_header: &mut SpHeader,
         sec_header: PusTcSecondaryHeader,
-        app_data: Option<&'app_data [u8]>,
+        app_data: Option<&'raw_data [u8]>,
         set_ccsds_len: bool,
     ) -> Self {
         sp_header.set_packet_type(PacketType::Tc);
@@ -268,7 +275,7 @@ impl<'app_data> PusTc<'app_data> {
         sph: &mut SpHeader,
         service: u8,
         subservice: u8,
-        app_data: Option<&'app_data [u8]>,
+        app_data: Option<&'raw_data [u8]>,
         set_ccsds_len: bool,
     ) -> Self {
         Self::new(
@@ -283,14 +290,6 @@ impl<'app_data> PusTc<'app_data> {
         &self.sp_header
     }
 
-    pub fn len_packed(&self) -> usize {
-        let mut length = PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
-        if let Some(app_data) = self.app_data {
-            length += app_data.len();
-        }
-        length
-    }
-
     pub fn set_ack_field(&mut self, ack: u8) -> bool {
         if ack > 0b1111 {
             return false;
@@ -336,42 +335,6 @@ impl<'app_data> PusTc<'app_data> {
         self.calc_own_crc16();
     }
 
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = 0;
-        let tc_header_len = size_of::<zc::PusTcSecondaryHeader>();
-        let total_size = self.len_packed();
-        if total_size > slice.len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: slice.len(),
-                expected: total_size,
-            })
-            .into());
-        }
-        self.sp_header.write_to_be_bytes(slice)?;
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
-        sec_header
-            .write_to_bytes(&mut slice[curr_idx..curr_idx + tc_header_len])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-
-        curr_idx += tc_header_len;
-        if let Some(app_data) = self.app_data {
-            slice[curr_idx..curr_idx + app_data.len()].copy_from_slice(app_data);
-            curr_idx += app_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            0,
-            curr_idx,
-            slice,
-        )?;
-        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
     #[cfg(feature = "alloc")]
     #[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
     pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PusError> {
@@ -405,7 +368,7 @@ impl<'app_data> PusTc<'app_data> {
 
     /// Create a [PusTc] instance from a raw slice. On success, it returns a tuple containing
     /// the instance and the found byte length of the packet.
-    pub fn from_bytes(slice: &'app_data [u8]) -> Result<(Self, usize), PusError> {
+    pub fn from_bytes(slice: &'raw_data [u8]) -> Result<(Self, usize), PusError> {
         let raw_data_len = slice.len();
         if raw_data_len < PUS_TC_MIN_LEN_WITHOUT_APP_DATA {
             return Err(PusError::RawDataTooShort(raw_data_len));
@@ -431,15 +394,79 @@ impl<'app_data> PusTc<'app_data> {
             calc_crc_on_serialization: false,
             crc16: Some(crc_from_raw_data(raw_data)?),
         };
-        verify_crc16_from_raw(raw_data, pus_tc.crc16.expect("CRC16 invalid"))?;
+        verify_crc16_ccitt_false_from_raw_to_pus_error(
+            raw_data,
+            pus_tc.crc16.expect("CRC16 invalid"),
+        )?;
         Ok((pus_tc, total_len))
     }
 
-    pub fn raw(&self) -> Option<&'app_data [u8]> {
+    #[deprecated(since = "0.5.2", note = "use raw_bytes() instead")]
+    pub fn raw(&self) -> Option<&'raw_data [u8]> {
+        self.raw_bytes()
+    }
+
+    /// If [Self] was constructed [Self::from_bytes], this function will return the slice it was
+    /// constructed from. Otherwise, [None] will be returned.
+    pub fn raw_bytes(&self) -> Option<&'raw_data [u8]> {
         self.raw_data
     }
 }
 
+impl SerializablePusPacket for PusTc<'_> {
+    fn len_packed(&self) -> usize {
+        let mut length = PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
+        if let Some(app_data) = self.app_data {
+            length += app_data.len();
+        }
+        length
+    }
+
+    /// Write the raw PUS byte representation to a provided buffer.
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
+        let mut curr_idx = 0;
+        let tc_header_len = size_of::<zc::PusTcSecondaryHeader>();
+        let total_size = self.len_packed();
+        if total_size > slice.len() {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: slice.len(),
+                expected: total_size,
+            })
+            .into());
+        }
+        self.sp_header.write_to_be_bytes(slice)?;
+        curr_idx += CCSDS_HEADER_LEN;
+        let sec_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
+        sec_header
+            .write_to_bytes(&mut slice[curr_idx..curr_idx + tc_header_len])
+            .ok_or(ByteConversionError::ZeroCopyToError)?;
+
+        curr_idx += tc_header_len;
+        if let Some(app_data) = self.app_data {
+            slice[curr_idx..curr_idx + app_data.len()].copy_from_slice(app_data);
+            curr_idx += app_data.len();
+        }
+        let crc16 = crc_procedure(
+            self.calc_crc_on_serialization,
+            &self.crc16,
+            0,
+            curr_idx,
+            slice,
+        )?;
+        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
+        curr_idx += 2;
+        Ok(curr_idx)
+    }
+}
+
+impl PartialEq for PusTc<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.app_data == other.app_data
+    }
+}
+
 //noinspection RsTraitImplementation
 impl CcsdsPacket for PusTc<'_> {
     ccsds_impl!();
@@ -476,7 +503,7 @@ impl GenericPusTcSecondaryHeader for PusTc<'_> {
 #[cfg(all(test, feature = "std"))]
 mod tests {
     use crate::ecss::PusVersion::PusC;
-    use crate::ecss::{PusError, PusPacket};
+    use crate::ecss::{PusError, PusPacket, SerializablePusPacket};
     use crate::tc::ACK_ALL;
     use crate::tc::{GenericPusTcSecondaryHeader, PusTc, PusTcSecondaryHeader};
     use crate::{ByteConversionError, SpHeader};
@@ -736,4 +763,20 @@ mod tests {
         assert_eq!(slice[11], 0xee);
         assert_eq!(slice[12], 0x63);
     }
+
+    #[test]
+    fn partial_eq_pus_tc() {
+        // new vs new simple
+        let pus_tc_1 = base_ping_tc_simple_ctor();
+        let pus_tc_2 = base_ping_tc_full_ctor();
+        assert_eq!(pus_tc_1, pus_tc_2);
+    }
+
+    #[test]
+    fn partial_eq_serialized_vs_derialized() {
+        let pus_tc = base_ping_tc_simple_ctor();
+        let mut buf = [0; 32];
+        pus_tc.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(pus_tc, PusTc::from_bytes(&buf).unwrap().0);
+    }
 }

src/time/cuc.rs

@@ -3,7 +3,10 @@
 //!
 //! The core data structure to do this is the [TimeProviderCcsdsEpoch] struct.
 use super::*;
+use chrono::Datelike;
 use core::fmt::Debug;
+use core::ops::{Add, AddAssign};
+use core::time::Duration;
 
 const MIN_CUC_LEN: usize = 2;
 
@@ -42,12 +45,14 @@ impl TryFrom<u8> for FractionalResolution {
 /// Please note that this function will panic if the fractional value is not smaller than
 /// the maximum number of fractions allowed for the particular resolution.
 /// (e.g. passing 270 when the resolution only allows 255 values).
+#[inline]
 pub fn convert_fractional_part_to_ns(fractional_part: FractionalPart) -> u64 {
     let div = fractional_res_to_div(fractional_part.0);
     assert!(fractional_part.1 < div);
     10_u64.pow(9) * fractional_part.1 as u64 / div as u64
 }
 
+#[inline(always)]
 pub const fn fractional_res_to_div(res: FractionalResolution) -> u32 {
     2_u32.pow(8 * res as u32) - 1
 }
@@ -89,6 +94,7 @@ pub fn fractional_part_from_subsec_ns(
 pub enum CucError {
     InvalidCounterWidth(u8),
     InvalidFractionResolution(FractionalResolution),
+    /// Invalid counter supplied.
     InvalidCounter(u8, u64),
     InvalidFractions(FractionalResolution, u64),
 }
@@ -97,16 +103,16 @@ impl Display for CucError {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         match self {
             CucError::InvalidCounterWidth(w) => {
-                write!(f, "invalid cuc counter byte width {}", w)
+                write!(f, "invalid cuc counter byte width {w}")
             }
             CucError::InvalidFractionResolution(w) => {
-                write!(f, "invalid cuc fractional part byte width {:?}", w)
+                write!(f, "invalid cuc fractional part byte width {w:?}")
             }
             CucError::InvalidCounter(w, c) => {
-                write!(f, "invalid cuc counter {} for width {}", c, w)
+                write!(f, "invalid cuc counter {c} for width {w}")
             }
             CucError::InvalidFractions(w, c) => {
-                write!(f, "invalid cuc fractional part {} for width {:?}", c, w)
+                write!(f, "invalid cuc fractional part {c} for width {w:?}")
             }
         }
     }
@@ -128,8 +134,8 @@ pub struct FractionalPart(FractionalResolution, u32);
 /// It has the capability to generate and read timestamps as specified in the CCSDS 301.0-B-4
 /// section 3.2 . The preamble field only has one byte, which allows a time code representation
 /// through the year 2094. The time is represented as a simple binary counter starting from the
-/// fixed CCSDS epoch (1958-01-01 00:00:00). It is possible to provide subsecond accuracy using the
-/// fractional field with various available [resolutions][FractionalResolution].
+/// fixed CCSDS epoch (1958-01-01T00:00:00+00:00). It is possible to provide subsecond accuracy
+/// using the fractional field with various available [resolutions][FractionalResolution].
 ///
 /// Having a preamble field of one byte limits the width of the counter
 /// type (generally seconds) to 4 bytes and the width of the fractions type to 3 bytes. This limits
@@ -228,9 +234,10 @@ impl TimeProviderCcsdsEpoch {
     /// The counter width will always be set to 4 bytes because the normal CCSDS epoch will overflow
     /// when using less than that.
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     pub fn from_now(fraction_resolution: FractionalResolution) -> Result<Self, StdTimestampError> {
         let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
-        let ccsds_epoch = unix_epoch_to_ccsds_epoch(now.as_secs());
+        let ccsds_epoch = unix_epoch_to_ccsds_epoch(now.as_secs() as i64);
         if fraction_resolution == FractionalResolution::Seconds {
             return Ok(Self::new(ccsds_epoch as u32));
         }
@@ -243,9 +250,10 @@ impl TimeProviderCcsdsEpoch {
     /// Updates the current time stamp from the current time. The fractional field width remains
     /// the same and will be updated accordingly.
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     pub fn update_from_now(&mut self) -> Result<(), StdTimestampError> {
         let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
-        self.counter.1 = unix_epoch_to_ccsds_epoch(now.as_secs()) as u32;
+        self.counter.1 = unix_epoch_to_ccsds_epoch(now.as_secs() as i64) as u32;
         if self.fractions.is_some() {
             self.fractions = fractional_part_from_subsec_ns(
                 self.fractions.unwrap().0,
@@ -255,6 +263,42 @@ impl TimeProviderCcsdsEpoch {
         Ok(())
     }
 
+    pub fn from_date_time(
+        dt: &DateTime<Utc>,
+        res: FractionalResolution,
+    ) -> Result<Self, TimestampError> {
+        // Year before CCSDS epoch is invalid.
+        if dt.year() < 1958 {
+            return Err(TimestampError::DateBeforeCcsdsEpoch(*dt));
+        }
+        Self::new_generic(
+            WidthCounterPair(4, dt.timestamp() as u32),
+            fractional_part_from_subsec_ns(res, dt.timestamp_subsec_nanos() as u64),
+        )
+        .map_err(|e| e.into())
+    }
+
+    pub fn from_unix_stamp(
+        unix_stamp: &UnixTimestamp,
+        res: FractionalResolution,
+    ) -> Result<Self, TimestampError> {
+        let ccsds_epoch = unix_epoch_to_ccsds_epoch(unix_stamp.unix_seconds);
+        // Negative CCSDS epoch is invalid.
+        if ccsds_epoch < 0 {
+            return Err(TimestampError::DateBeforeCcsdsEpoch(
+                unix_stamp.as_date_time().unwrap(),
+            ));
+        }
+        if ccsds_epoch > u32::MAX as i64 {
+            return Err(CucError::InvalidCounter(4, ccsds_epoch as u64).into());
+        }
+        let mut fractions = None;
+        if let Some(subsec_millis) = unix_stamp.subsecond_millis {
+            fractions = fractional_part_from_subsec_ns(res, subsec_millis as u64 * 10_u64.pow(6));
+        }
+        Self::new_generic(WidthCounterPair(4, ccsds_epoch as u32), fractions).map_err(|e| e.into())
+    }
+
     pub fn new_u16_counter(counter: u16) -> Self {
         // These values are definitely valid, so it is okay to unwrap here.
         Self::new_generic(WidthCounterPair(2, counter as u32), None).unwrap()
@@ -351,6 +395,11 @@ impl TimeProviderCcsdsEpoch {
         pfield & 0b11
     }
 
+    #[inline]
+    fn unix_seconds(&self) -> i64 {
+        ccsds_epoch_to_unix_epoch(self.counter.1 as i64)
+    }
+
     /// This returns the length of the individual components of the CUC timestamp in addition
     /// to the total size.
     ///
@@ -543,10 +592,19 @@ impl CcsdsTimeProvider for TimeProviderCcsdsEpoch {
         CcsdsTimeCodes::CucCcsdsEpoch
     }
 
-    /// Please note that this function only works as intended if the time counter resolution
-    /// is one second.
     fn unix_seconds(&self) -> i64 {
-        ccsds_epoch_to_unix_epoch(self.counter.1 as u64) as i64
+        self.unix_seconds()
+    }
+
+    fn subsecond_millis(&self) -> Option<u16> {
+        if let Some(fractions) = self.fractions {
+            if fractions.0 == FractionalResolution::Seconds {
+                return None;
+            }
+            // Rounding down here is the correct approach.
+            return Some((convert_fractional_part_to_ns(fractions) / 10_u32.pow(6) as u64) as u16);
+        }
+        None
     }
 
     fn date_time(&self) -> Option<DateTime<Utc>> {
@@ -563,6 +621,95 @@ impl CcsdsTimeProvider for TimeProviderCcsdsEpoch {
     }
 }
 
+fn get_provider_values_after_duration_addition(
+    provider: &TimeProviderCcsdsEpoch,
+    duration: Duration,
+) -> (u32, Option<FractionalPart>) {
+    let mut new_counter = provider.counter.1;
+    let subsec_nanos = duration.subsec_nanos();
+    let mut increment_counter = |amount: u32| {
+        let mut sum: u64 = 0;
+        let mut counter_inc_handler = |max_val: u64| {
+            sum = new_counter as u64 + amount as u64;
+            if sum >= max_val {
+                new_counter = (sum % max_val) as u32;
+                return;
+            }
+            new_counter = sum as u32;
+        };
+        match provider.counter.0 {
+            1 => counter_inc_handler(u8::MAX as u64),
+            2 => counter_inc_handler(u16::MAX as u64),
+            3 => counter_inc_handler((2_u32.pow(24) - 1) as u64),
+            4 => counter_inc_handler(u32::MAX as u64),
+            _ => {
+                // Should never happen
+                panic!("invalid counter width")
+            }
+        }
+    };
+    let fractional_part = if let Some(fractional_part) = &provider.fractions {
+        let fractional_increment =
+            fractional_part_from_subsec_ns(fractional_part.0, subsec_nanos as u64).unwrap();
+        let mut increment_fractions = |resolution| {
+            let mut new_fractions = fractional_part.1 + fractional_increment.1;
+            let max_fractions = fractional_res_to_div(resolution);
+            if new_fractions > max_fractions {
+                increment_counter(1);
+                new_fractions -= max_fractions;
+            }
+            Some(FractionalPart(resolution, new_fractions))
+        };
+        match fractional_increment.0 {
+            FractionalResolution::Seconds => None,
+            _ => increment_fractions(fractional_increment.0),
+        }
+    } else {
+        None
+    };
+    increment_counter(duration.as_secs() as u32);
+    (new_counter, fractional_part)
+}
+
+impl AddAssign<Duration> for TimeProviderCcsdsEpoch {
+    fn add_assign(&mut self, duration: Duration) {
+        let (new_counter, new_fractional_part) =
+            get_provider_values_after_duration_addition(self, duration);
+        self.counter.1 = new_counter;
+        if self.fractions.is_some() {
+            self.fractions = new_fractional_part;
+        }
+    }
+}
+
+impl Add<Duration> for TimeProviderCcsdsEpoch {
+    type Output = Self;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        let (new_counter, new_fractional_part) =
+            get_provider_values_after_duration_addition(&self, duration);
+        if let Some(fractional_part) = new_fractional_part {
+            // The generated fractional part should always be valid, so its okay to unwrap here.
+            return Self::new_with_fractions(new_counter, fractional_part).unwrap();
+        }
+        Self::new(new_counter)
+    }
+}
+
+impl Add<Duration> for &TimeProviderCcsdsEpoch {
+    type Output = TimeProviderCcsdsEpoch;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        let (new_counter, new_fractional_part) =
+            get_provider_values_after_duration_addition(self, duration);
+        if let Some(fractional_part) = new_fractional_part {
+            // The generated fractional part should always be valid, so its okay to unwrap here.
+            return Self::Output::new_with_fractions(new_counter, fractional_part).unwrap();
+        }
+        Self::Output::new(new_counter)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -599,6 +746,7 @@ mod tests {
         let zero_cuc = zero_cuc.unwrap();
         let res = zero_cuc.write_to_bytes(&mut buf);
         assert!(res.is_ok());
+        assert!(zero_cuc.subsecond_millis().is_none());
         assert_eq!(zero_cuc.len_as_bytes(), 5);
         assert_eq!(pfield_len(buf[0]), 1);
         let written = res.unwrap();
@@ -947,4 +1095,31 @@ mod tests {
         // Assert that the maximum resolution can be reached
         assert_eq!(fractions.1, 2_u32.pow(3 * 8) - 2);
     }
+
+    #[test]
+    fn add_duration_basic() {
+        let mut cuc_stamp = TimeProviderCcsdsEpoch::new(200);
+        cuc_stamp.set_fractional_resolution(FractionalResolution::FifteenUs);
+        let duration = Duration::from_millis(2500);
+        cuc_stamp += duration;
+        assert_eq!(cuc_stamp.width_counter_pair().1, 202);
+        let fractions = cuc_stamp.width_fractions_pair().unwrap().1;
+        let expected_val =
+            (0.5 * fractional_res_to_div(FractionalResolution::FifteenUs) as f64).floor() as u32;
+        assert_eq!(fractions, expected_val);
+        let cuc_stamp2 = cuc_stamp + Duration::from_millis(501);
+        // What I would roughly expect
+        assert_eq!(cuc_stamp2.counter.1, 203);
+        assert!(cuc_stamp2.fractions.unwrap().1 < 100);
+        assert!(cuc_stamp2.subsecond_millis().unwrap() <= 1);
+    }
+
+    #[test]
+    fn add_duration_overflow() {
+        let mut cuc_stamp =
+            TimeProviderCcsdsEpoch::new_generic(WidthCounterPair(1, 255), None).unwrap();
+        let duration = Duration::from_secs(10);
+        cuc_stamp += duration;
+        assert_eq!(cuc_stamp.counter.1, 10);
+    }
 }

src/time/mod.rs

@@ -1,7 +1,10 @@
 //! CCSDS Time Code Formats according to [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
 use crate::{ByteConversionError, SizeMissmatch};
 use chrono::{DateTime, LocalResult, TimeZone, Utc};
+use core::cmp::Ordering;
 use core::fmt::{Display, Formatter};
+use core::ops::{Add, AddAssign};
+use core::time::Duration;
 
 #[allow(unused_imports)]
 #[cfg(not(feature = "std"))]
@@ -20,6 +23,7 @@ pub mod cuc;
 
 pub const DAYS_CCSDS_TO_UNIX: i32 = -4383;
 pub const SECONDS_PER_DAY: u32 = 86400;
+pub const MS_PER_DAY: u32 = SECONDS_PER_DAY * 1000;
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@@ -55,6 +59,7 @@ pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCodes, u8> {
 
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[non_exhaustive]
 pub enum TimestampError {
     /// Contains tuple where first value is the expected time code and the second
     /// value is the found raw value
@@ -62,6 +67,7 @@ pub enum TimestampError {
     ByteConversionError(ByteConversionError),
     CdsError(cds::CdsError),
     CucError(cuc::CucError),
+    DateBeforeCcsdsEpoch(DateTime<Utc>),
     CustomEpochNotSupported,
 }
 
@@ -105,18 +111,20 @@ impl Display for TimestampError {
             TimestampError::InvalidTimeCode(time_code, raw_val) => {
                 write!(
                     f,
-                    "invalid raw time code value {} for time code {:?}",
-                    raw_val, time_code
+                    "invalid raw time code value {raw_val} for time code {time_code:?}"
                 )
             }
             TimestampError::CdsError(e) => {
-                write!(f, "cds error {}", e)
+                write!(f, "cds error {e}")
             }
             TimestampError::CucError(e) => {
-                write!(f, "cuc error {}", e)
+                write!(f, "cuc error {e}")
             }
             TimestampError::ByteConversionError(e) => {
-                write!(f, "byte conversion error {}", e)
+                write!(f, "byte conversion error {e}")
+            }
+            TimestampError::DateBeforeCcsdsEpoch(e) => {
+                write!(f, "datetime with date before ccsds epoch: {e}")
             }
             TimestampError::CustomEpochNotSupported => {
                 write!(f, "custom epochs are not supported")
@@ -148,28 +156,28 @@ pub fn seconds_since_epoch() -> f64 {
 
 /// Convert UNIX days to CCSDS days
 ///
-///  - CCSDS epoch: 1958 January 1
-///  - UNIX Epoch: 1970 January 1
+///  - CCSDS epoch: 1958-01-01T00:00:00+00:00
+///  - UNIX Epoch: 1970-01-01T00:00:00+00:00
 pub const fn unix_to_ccsds_days(unix_days: i64) -> i64 {
     unix_days - DAYS_CCSDS_TO_UNIX as i64
 }
 
 /// Convert CCSDS days to UNIX days
 ///
-///  - CCSDS epoch: 1958 January 1
-///  - UNIX Epoch: 1970 January 1
+///  - CCSDS epoch: 1958-01-01T00:00:00+00:00
+///  - UNIX Epoch: 1970-01-01T00:00:00+00:00
 pub const fn ccsds_to_unix_days(ccsds_days: i64) -> i64 {
     ccsds_days + DAYS_CCSDS_TO_UNIX as i64
 }
 
 /// Similar to [unix_to_ccsds_days] but converts the epoch instead, which is the number of elpased
 /// seconds since the CCSDS and UNIX epoch times.
-pub const fn unix_epoch_to_ccsds_epoch(unix_epoch: u64) -> u64 {
-    (unix_epoch as i64 - (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)) as u64
+pub const fn unix_epoch_to_ccsds_epoch(unix_epoch: i64) -> i64 {
+    unix_epoch - (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)
 }
 
-pub const fn ccsds_epoch_to_unix_epoch(ccsds_epoch: u64) -> u64 {
-    (ccsds_epoch as i64 + (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)) as u64
+pub const fn ccsds_epoch_to_unix_epoch(ccsds_epoch: i64) -> i64 {
+    ccsds_epoch + (DAYS_CCSDS_TO_UNIX as i64 * SECONDS_PER_DAY as i64)
 }
 
 #[cfg(feature = "std")]
@@ -199,6 +207,9 @@ pub trait TimeReader {
 }
 
 /// Trait for generic CCSDS time providers.
+///
+/// The UNIX helper methods and the [Self::date_time] method are not strictly necessary but extremely
+/// practical because they are a very common and simple exchange format for time information.
 pub trait CcsdsTimeProvider {
     fn len_as_bytes(&self) -> usize;
 
@@ -208,10 +219,203 @@ pub trait CcsdsTimeProvider {
     /// in big endian format.
     fn p_field(&self) -> (usize, [u8; 2]);
     fn ccdsd_time_code(&self) -> CcsdsTimeCodes;
+
     fn unix_seconds(&self) -> i64;
+    fn subsecond_millis(&self) -> Option<u16>;
+    fn unix_stamp(&self) -> UnixTimestamp {
+        if self.subsecond_millis().is_none() {
+            return UnixTimestamp::new_only_seconds(self.unix_seconds());
+        }
+        UnixTimestamp::const_new(self.unix_seconds(), self.subsecond_millis().unwrap())
+    }
+
     fn date_time(&self) -> Option<DateTime<Utc>>;
 }
 
+/// UNIX timestamp: Elapsed seconds since 1970-01-01T00:00:00+00:00.
+///
+/// Also can optionally include subsecond millisecond for greater accuracy. Please note that a
+/// subsecond millisecond value of 0 gets converted to [None].
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct UnixTimestamp {
+    pub unix_seconds: i64,
+    subsecond_millis: Option<u16>,
+}
+
+impl UnixTimestamp {
+    /// Returns none if the subsecond millisecond value is larger than 999. 0 is converted to
+    /// a [None] value.
+    pub fn new(unix_seconds: i64, subsec_millis: u16) -> Option<Self> {
+        if subsec_millis > 999 {
+            return None;
+        }
+        Some(Self::const_new(unix_seconds, subsec_millis))
+    }
+
+    /// Like [Self::new] but const. Panics if the subsecond value is larger than 999.
+    pub const fn const_new(unix_seconds: i64, subsec_millis: u16) -> Self {
+        if subsec_millis > 999 {
+            panic!("subsec milliseconds exceeds 999");
+        }
+        let subsecond_millis = if subsec_millis == 0 {
+            None
+        } else {
+            Some(subsec_millis)
+        };
+        Self {
+            unix_seconds,
+            subsecond_millis,
+        }
+    }
+
+    pub fn new_only_seconds(unix_seconds: i64) -> Self {
+        Self {
+            unix_seconds,
+            subsecond_millis: None,
+        }
+    }
+
+    pub fn subsecond_millis(&self) -> Option<u16> {
+        self.subsecond_millis
+    }
+
+    #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+    pub fn from_now() -> Result<Self, SystemTimeError> {
+        let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH)?;
+        let epoch = now.as_secs();
+        Ok(Self::const_new(epoch as i64, now.subsec_millis() as u16))
+    }
+
+    #[inline]
+    pub fn unix_seconds_f64(&self) -> f64 {
+        let mut secs = self.unix_seconds as f64;
+        if let Some(subsec_millis) = self.subsecond_millis {
+            secs += subsec_millis as f64 / 1000.0;
+        }
+        secs
+    }
+
+    pub fn as_date_time(&self) -> LocalResult<DateTime<Utc>> {
+        Utc.timestamp_opt(
+            self.unix_seconds,
+            self.subsecond_millis.unwrap_or(0) as u32 * 10_u32.pow(6),
+        )
+    }
+}
+
+impl From<DateTime<Utc>> for UnixTimestamp {
+    fn from(value: DateTime<Utc>) -> Self {
+        Self::const_new(value.timestamp(), value.timestamp_subsec_millis() as u16)
+    }
+}
+
+impl PartialOrd for UnixTimestamp {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if self == other {
+            return Some(Ordering::Equal);
+        }
+        match self.unix_seconds.cmp(&other.unix_seconds) {
+            Ordering::Less => return Some(Ordering::Less),
+            Ordering::Greater => return Some(Ordering::Greater),
+            _ => (),
+        }
+
+        match self
+            .subsecond_millis()
+            .unwrap_or(0)
+            .cmp(&other.subsecond_millis().unwrap_or(0))
+        {
+            Ordering::Less => {
+                return if self.unix_seconds < 0 {
+                    Some(Ordering::Greater)
+                } else {
+                    Some(Ordering::Less)
+                }
+            }
+            Ordering::Greater => {
+                return if self.unix_seconds < 0 {
+                    Some(Ordering::Less)
+                } else {
+                    Some(Ordering::Greater)
+                }
+            }
+            Ordering::Equal => (),
+        }
+        Some(Ordering::Equal)
+    }
+}
+
+impl Ord for UnixTimestamp {
+    fn cmp(&self, other: &Self) -> Ordering {
+        PartialOrd::partial_cmp(self, other).unwrap()
+    }
+}
+
+fn get_new_stamp_after_addition(
+    current_stamp: &UnixTimestamp,
+    duration: Duration,
+) -> UnixTimestamp {
+    let mut new_subsec_millis =
+        current_stamp.subsecond_millis().unwrap_or(0) + duration.subsec_millis() as u16;
+    let mut new_unix_seconds = current_stamp.unix_seconds;
+    let mut increment_seconds = |value: u32| {
+        if new_unix_seconds < 0 {
+            new_unix_seconds = new_unix_seconds
+                .checked_sub(value.into())
+                .expect("new unix seconds would exceed i64::MIN");
+        } else {
+            new_unix_seconds = new_unix_seconds
+                .checked_add(value.into())
+                .expect("new unix seconds would exceed i64::MAX");
+        }
+    };
+    if new_subsec_millis >= 1000 {
+        new_subsec_millis -= 1000;
+        increment_seconds(1);
+    }
+    increment_seconds(
+        duration
+            .as_secs()
+            .try_into()
+            .expect("duration seconds exceeds u32::MAX"),
+    );
+    UnixTimestamp::const_new(new_unix_seconds, new_subsec_millis)
+}
+
+/// Please note that this operation will panic on the following conditions:
+///
+/// - Unix seconds after subtraction for stamps before the unix epoch exceeds [i64::MIN].
+/// - Unix seconds after addition  exceeds [i64::MAX].
+/// - Seconds from duration to add exceeds [u32::MAX].
+impl AddAssign<Duration> for UnixTimestamp {
+    fn add_assign(&mut self, duration: Duration) {
+        *self = get_new_stamp_after_addition(self, duration);
+    }
+}
+
+/// Please note that this operation will panic for the following conditions:
+///
+/// - Unix seconds after subtraction for stamps before the unix epoch exceeds [i64::MIN].
+/// - Unix seconds after addition  exceeds [i64::MAX].
+/// - Unix seconds exceeds [u32::MAX].
+impl Add<Duration> for UnixTimestamp {
+    type Output = Self;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        get_new_stamp_after_addition(&self, duration)
+    }
+}
+
+impl Add<Duration> for &UnixTimestamp {
+    type Output = UnixTimestamp;
+
+    fn add(self, duration: Duration) -> Self::Output {
+        get_new_stamp_after_addition(self, duration)
+    }
+}
+
 #[cfg(all(test, feature = "std"))]
 mod tests {
     use super::*;
@@ -234,10 +438,116 @@ mod tests {
             .duration_since(SystemTime::UNIX_EPOCH)
             .unwrap();
         let unix_epoch = now.as_secs();
-        let ccsds_epoch = unix_epoch_to_ccsds_epoch(now.as_secs());
+        let ccsds_epoch = unix_epoch_to_ccsds_epoch(now.as_secs() as i64) as u64;
         assert!(ccsds_epoch > unix_epoch);
         assert_eq!((ccsds_epoch - unix_epoch) % SECONDS_PER_DAY as u64, 0);
         let days_diff = (ccsds_epoch - unix_epoch) / SECONDS_PER_DAY as u64;
         assert_eq!(days_diff, -DAYS_CCSDS_TO_UNIX as u64);
     }
+
+    #[test]
+    fn basic_unix_stamp_test() {
+        let stamp = UnixTimestamp::new_only_seconds(-200);
+        assert_eq!(stamp.unix_seconds, -200);
+        assert!(stamp.subsecond_millis().is_none());
+        let stamp = UnixTimestamp::new_only_seconds(250);
+        assert_eq!(stamp.unix_seconds, 250);
+        assert!(stamp.subsecond_millis().is_none());
+    }
+
+    #[test]
+    fn basic_float_unix_stamp_test() {
+        let stamp = UnixTimestamp::new(500, 600).unwrap();
+        assert!(stamp.subsecond_millis.is_some());
+        assert_eq!(stamp.unix_seconds, 500);
+        let subsec_millis = stamp.subsecond_millis().unwrap();
+        assert_eq!(subsec_millis, 600);
+        assert!((500.6 - stamp.unix_seconds_f64()).abs() < 0.0001);
+    }
+
+    #[test]
+    fn test_ord_larger() {
+        let stamp0 = UnixTimestamp::new_only_seconds(5);
+        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        assert!(stamp1 > stamp0);
+        assert!(stamp2 > stamp0);
+        assert!(stamp2 > stamp1);
+    }
+
+    #[test]
+    fn test_ord_smaller() {
+        let stamp0 = UnixTimestamp::new_only_seconds(5);
+        let stamp1 = UnixTimestamp::new(5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(6);
+        assert!(stamp0 < stamp1);
+        assert!(stamp0 < stamp2);
+        assert!(stamp1 < stamp2);
+    }
+
+    #[test]
+    fn test_ord_larger_neg_numbers() {
+        let stamp0 = UnixTimestamp::new_only_seconds(-5);
+        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        assert!(stamp0 > stamp1);
+        assert!(stamp0 > stamp2);
+        assert!(stamp1 > stamp2);
+        assert!(stamp1 >= stamp2);
+        assert!(stamp0 >= stamp1);
+    }
+
+    #[test]
+    fn test_ord_smaller_neg_numbers() {
+        let stamp0 = UnixTimestamp::new_only_seconds(-5);
+        let stamp1 = UnixTimestamp::new(-5, 500).unwrap();
+        let stamp2 = UnixTimestamp::new_only_seconds(-6);
+        assert!(stamp2 < stamp1);
+        assert!(stamp2 < stamp0);
+        assert!(stamp1 < stamp0);
+        assert!(stamp1 <= stamp0);
+        assert!(stamp2 <= stamp1);
+    }
+
+    #[test]
+    fn test_eq() {
+        let stamp0 = UnixTimestamp::new(5, 0).unwrap();
+        let stamp1 = UnixTimestamp::new_only_seconds(5);
+        assert_eq!(stamp0, stamp1);
+        assert!(stamp0 <= stamp1);
+        assert!(stamp0 >= stamp1);
+        assert!(!(stamp0 < stamp1));
+        assert!(!(stamp0 > stamp1));
+    }
+
+    #[test]
+    fn test_addition() {
+        let mut stamp0 = UnixTimestamp::new_only_seconds(1);
+        stamp0 += Duration::from_secs(5);
+        assert_eq!(stamp0.unix_seconds, 6);
+        assert!(stamp0.subsecond_millis().is_none());
+        let stamp1 = stamp0 + Duration::from_millis(500);
+        assert_eq!(stamp1.unix_seconds, 6);
+        assert!(stamp1.subsecond_millis().is_some());
+        assert_eq!(stamp1.subsecond_millis().unwrap(), 500);
+    }
+
+    #[test]
+    fn test_addition_on_ref() {
+        let stamp0 = &UnixTimestamp::new(20, 500).unwrap();
+        let stamp1 = stamp0 + Duration::from_millis(2500);
+        assert_eq!(stamp1.unix_seconds, 23);
+        assert!(stamp1.subsecond_millis().is_none());
+    }
+
+    #[test]
+    fn test_addition_spillover() {
+        let mut stamp0 = UnixTimestamp::new(1, 900).unwrap();
+        stamp0 += Duration::from_millis(100);
+        assert_eq!(stamp0.unix_seconds, 2);
+        assert!(stamp0.subsecond_millis().is_none());
+        stamp0 += Duration::from_millis(1100);
+        assert_eq!(stamp0.unix_seconds, 3);
+        assert_eq!(stamp0.subsecond_millis().unwrap(), 100);
+    }
 }

src/tm.rs

@@ -1,12 +1,13 @@
 //! This module contains all components required to create a ECSS PUS C telemetry packets according
 //! to [ECSS-E-ST-70-41C](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/).
 use crate::ecss::{
-    ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
-    verify_crc16_from_raw, CrcType, PusError, PusPacket, PusVersion, CRC_CCITT_FALSE,
+    calc_pus_crc16, ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls,
+    user_data_from_raw, verify_crc16_ccitt_false_from_raw_to_pus_error, CrcType, PusError,
+    PusPacket, PusVersion, SerializablePusPacket,
 };
 use crate::{
     ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SizeMissmatch, SpHeader,
-    CCSDS_HEADER_LEN,
+    CCSDS_HEADER_LEN, CRC_CCITT_FALSE, MAX_APID, MAX_SEQ_COUNT,
 };
 use core::mem::size_of;
 #[cfg(feature = "serde")]
@@ -48,7 +49,7 @@ pub mod zc {
 
     pub struct PusTmSecHeader<'slice> {
         pub(crate) zc_header: PusTmSecHeaderWithoutTimestamp,
-        pub(crate) timestamp: &'slice [u8],
+        pub(crate) timestamp: Option<&'slice [u8]>,
     }
 
     impl TryFrom<crate::tm::PusTmSecondaryHeader<'_>> for PusTmSecHeaderWithoutTimestamp {
@@ -115,20 +116,17 @@ pub struct PusTmSecondaryHeader<'stamp> {
     pub subservice: u8,
     pub msg_counter: u16,
     pub dest_id: u16,
-    pub time_stamp: &'stamp [u8],
+    pub timestamp: Option<&'stamp [u8]>,
 }
 
 impl<'stamp> PusTmSecondaryHeader<'stamp> {
-    pub fn new_simple(service: u8, subservice: u8, time_stamp: &'stamp [u8]) -> Self {
-        PusTmSecondaryHeader {
-            pus_version: PusVersion::PusC,
-            sc_time_ref_status: 0,
-            service,
-            subservice,
-            msg_counter: 0,
-            dest_id: 0,
-            time_stamp,
-        }
+    pub fn new_simple(service: u8, subservice: u8, timestamp: &'stamp [u8]) -> Self {
+        Self::new(service, subservice, 0, 0, Some(timestamp))
+    }
+
+    /// Like [Self::new_simple] but without a timestamp.
+    pub fn new_simple_no_timestamp(service: u8, subservice: u8) -> Self {
+        Self::new(service, subservice, 0, 0, None)
     }
 
     pub fn new(
@@ -136,7 +134,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
         subservice: u8,
         msg_counter: u16,
         dest_id: u16,
-        time_stamp: &'stamp [u8],
+        timestamp: Option<&'stamp [u8]>,
     ) -> Self {
         PusTmSecondaryHeader {
             pus_version: PusVersion::PusC,
@@ -145,7 +143,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
             subservice,
             msg_counter,
             dest_id,
-            time_stamp,
+            timestamp,
         }
     }
 }
@@ -187,14 +185,13 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
             subservice: sec_header.zc_header.subservice(),
             msg_counter: sec_header.zc_header.msg_counter(),
             dest_id: sec_header.zc_header.dest_id(),
-            time_stamp: sec_header.timestamp,
+            timestamp: sec_header.timestamp,
         })
     }
 }
 
-/// This class models a PUS telemetry and which can also be used. It is the primary data
-/// structure to generate the raw byte representation of PUS telemetry or to
-/// deserialize from one from raw bytes.
+/// This class models the PUS C telemetry packet. It is the primary data structure to generate the
+/// raw byte representation of PUS telemetry or to deserialize from one from raw bytes.
 ///
 /// This class also derives the [serde::Serialize] and [serde::Deserialize] trait if the [serde]
 /// feature is used which allows to send around TM packets in a raw byte format using a serde
@@ -204,23 +201,24 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
 ///
 /// # Lifetimes
 ///
-/// * `'src_data` - Life time of a buffer where the user provided time stamp and source data will
-///    be serialized into.
-#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+/// * `'raw_data` - If the TM is not constructed from a raw slice, this will be the life time of
+///    a buffer where the user provided time stamp and source data will be serialized into. If it
+///    is, this is the lifetime of the raw byte slice it is constructed from.
+#[derive(Eq, Debug, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct PusTm<'src_data> {
+pub struct PusTm<'raw_data> {
     pub sp_header: SpHeader,
-    pub sec_header: PusTmSecondaryHeader<'src_data>,
+    pub sec_header: PusTmSecondaryHeader<'raw_data>,
     /// If this is set to false, a manual call to [PusTm::calc_own_crc16] or
     /// [PusTm::update_packet_fields] is necessary for the serialized or cached CRC16 to be valid.
     pub calc_crc_on_serialization: bool,
     #[cfg_attr(feature = "serde", serde(skip))]
-    raw_data: Option<&'src_data [u8]>,
-    source_data: Option<&'src_data [u8]>,
+    raw_data: Option<&'raw_data [u8]>,
+    source_data: Option<&'raw_data [u8]>,
     crc16: Option<u16>,
 }
 
-impl<'src_data> PusTm<'src_data> {
+impl<'raw_data> PusTm<'raw_data> {
     /// Generates a new struct instance.
     ///
     /// # Arguments
@@ -235,8 +233,8 @@ impl<'src_data> PusTm<'src_data> {
     ///     the correct value to this field manually
     pub fn new(
         sp_header: &mut SpHeader,
-        sec_header: PusTmSecondaryHeader<'src_data>,
-        source_data: Option<&'src_data [u8]>,
+        sec_header: PusTmSecondaryHeader<'raw_data>,
+        source_data: Option<&'raw_data [u8]>,
         set_ccsds_len: bool,
     ) -> Self {
         sp_header.set_packet_type(PacketType::Tm);
@@ -255,20 +253,11 @@ impl<'src_data> PusTm<'src_data> {
         pus_tm
     }
 
-    pub fn len_packed(&self) -> usize {
-        let mut length = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA;
-        length += self.sec_header.time_stamp.len();
-        if let Some(src_data) = self.source_data {
-            length += src_data.len();
-        }
-        length
+    pub fn timestamp(&self) -> Option<&'raw_data [u8]> {
+        self.sec_header.timestamp
     }
 
-    pub fn time_stamp(&self) -> &'src_data [u8] {
-        self.sec_header.time_stamp
-    }
-
-    pub fn source_data(&self) -> Option<&'src_data [u8]> {
+    pub fn source_data(&self) -> Option<&'raw_data [u8]> {
         self.source_data
     }
 
@@ -304,7 +293,9 @@ impl<'src_data> PusTm<'src_data> {
         digest.update(sph_zc.as_bytes());
         let pus_tc_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
         digest.update(pus_tc_header.as_bytes());
-        digest.update(self.sec_header.time_stamp);
+        if let Some(stamp) = self.sec_header.timestamp {
+            digest.update(stamp);
+        }
         if let Some(src_data) = self.source_data {
             digest.update(src_data);
         }
@@ -317,52 +308,15 @@ impl<'src_data> PusTm<'src_data> {
         self.calc_own_crc16();
     }
 
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = 0;
-        let total_size = self.len_packed();
-        if total_size > slice.len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
-                found: slice.len(),
-                expected: total_size,
-            })
-            .into());
-        }
-        self.sp_header
-            .write_to_be_bytes(&mut slice[0..CCSDS_HEADER_LEN])?;
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header_len = size_of::<zc::PusTmSecHeaderWithoutTimestamp>();
-        let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
-        sec_header
-            .write_to_bytes(&mut slice[curr_idx..curr_idx + sec_header_len])
-            .ok_or(ByteConversionError::ZeroCopyToError)?;
-        curr_idx += sec_header_len;
-        let timestamp_len = self.sec_header.time_stamp.len();
-        slice[curr_idx..curr_idx + timestamp_len].copy_from_slice(self.sec_header.time_stamp);
-        curr_idx += timestamp_len;
-        if let Some(src_data) = self.source_data {
-            slice[curr_idx..curr_idx + src_data.len()].copy_from_slice(src_data);
-            curr_idx += src_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            0,
-            curr_idx,
-            slice,
-        )?;
-        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
     /// Append the raw PUS byte representation to a provided [alloc::vec::Vec]
     #[cfg(feature = "alloc")]
     #[cfg_attr(doc_cfg, doc(cfg(feature = "alloc")))]
     pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PusError> {
         let sph_zc = crate::zc::SpHeader::from(self.sp_header);
-        let mut appended_len =
-            PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA + self.sec_header.time_stamp.len();
+        let mut appended_len = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA;
+        if let Some(timestamp) = self.sec_header.timestamp {
+            appended_len += timestamp.len();
+        }
         if let Some(src_data) = self.source_data {
             appended_len += src_data.len();
         };
@@ -374,8 +328,10 @@ impl<'src_data> PusTm<'src_data> {
         let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
         vec.extend_from_slice(sec_header.as_bytes());
         ser_len += sec_header.as_bytes().len();
-        vec.extend_from_slice(self.sec_header.time_stamp);
-        ser_len += self.sec_header.time_stamp.len();
+        if let Some(timestamp) = self.sec_header.timestamp {
+            ser_len += timestamp.len();
+            vec.extend_from_slice(timestamp);
+        }
         if let Some(src_data) = self.source_data {
             vec.extend_from_slice(src_data);
             ser_len += src_data.len();
@@ -395,7 +351,7 @@ impl<'src_data> PusTm<'src_data> {
     /// the instance and the found byte length of the packet. The timestamp length needs to be
     /// known beforehand.
     pub fn from_bytes(
-        slice: &'src_data [u8],
+        slice: &'raw_data [u8],
         timestamp_len: usize,
     ) -> Result<(Self, usize), PusError> {
         let raw_data_len = slice.len();
@@ -414,9 +370,13 @@ impl<'src_data> PusTm<'src_data> {
         )
         .ok_or(ByteConversionError::ZeroCopyFromError)?;
         current_idx += PUC_TM_MIN_SEC_HEADER_LEN;
+        let mut timestamp = None;
+        if timestamp_len > 0 {
+            timestamp = Some(&slice[current_idx..current_idx + timestamp_len]);
+        }
         let zc_sec_header_wrapper = zc::PusTmSecHeader {
             zc_header: sec_header_zc,
-            timestamp: &slice[current_idx..current_idx + timestamp_len],
+            timestamp,
         };
         current_idx += timestamp_len;
         let raw_data = &slice[0..total_len];
@@ -428,9 +388,156 @@ impl<'src_data> PusTm<'src_data> {
             calc_crc_on_serialization: false,
             crc16: Some(crc_from_raw_data(raw_data)?),
         };
-        verify_crc16_from_raw(raw_data, pus_tm.crc16.expect("CRC16 invalid"))?;
+        verify_crc16_ccitt_false_from_raw_to_pus_error(
+            raw_data,
+            pus_tm.crc16.expect("CRC16 invalid"),
+        )?;
         Ok((pus_tm, total_len))
     }
+
+    /// If [Self] was constructed [Self::from_bytes], this function will return the slice it was
+    /// constructed from. Otherwise, [None] will be returned.
+    pub fn raw_bytes(&self) -> Option<&'raw_data [u8]> {
+        self.raw_data
+    }
+}
+
+/// This is a helper class to update certain fields in a raw PUS telemetry packet directly in place.
+/// This can be more efficient than creating a full [PusTm], modifying the fields and then writing
+/// it back to another buffer.
+///
+/// Please note that the [Self::finish] method has to be called for the PUS TM CRC16 to be valid
+/// after changing fields of the TM packet. Furthermore, the constructor of this class will not
+/// do any checks except a length check to ensure that all relevant fields can be updated without
+/// a panic. If a full validity check of the PUS TM packet is required, it is recommended
+/// to construct a full [PusTm] object from the raw bytestream first.
+pub struct PusTmZeroCopyWriter<'raw> {
+    raw_tm: &'raw mut [u8],
+}
+
+impl<'raw> PusTmZeroCopyWriter<'raw> {
+    /// This function will not do any other checks on the raw data other than a length check
+    /// for all internal fields which can be updated. It is the responsibility of the user to ensure
+    /// the raw slice contains a valid telemetry packet. The slice should have the exact length
+    /// of the telemetry packet for this class to work properly.
+    pub fn new(raw_tm: &'raw mut [u8]) -> Option<Self> {
+        if raw_tm.len() < 13 {
+            return None;
+        }
+        Some(Self { raw_tm })
+    }
+
+    pub fn service(&self) -> u8 {
+        self.raw_tm[7]
+    }
+
+    pub fn subservice(&self) -> u8 {
+        self.raw_tm[8]
+    }
+
+    /// Set the sequence count. Returns false and does not update the value if the passed value
+    /// exceeds [MAX_APID].
+    pub fn set_apid(&mut self, apid: u16) -> bool {
+        if apid > MAX_APID {
+            return false;
+        }
+        // Clear APID part of the raw packet ID
+        let updated_apid =
+            ((((self.raw_tm[0] as u16) << 8) | self.raw_tm[1] as u16) & !MAX_APID) | apid;
+        self.raw_tm[0..2].copy_from_slice(&updated_apid.to_be_bytes());
+        true
+    }
+
+    /// This function sets the message counter in the PUS TM secondary header.
+    pub fn set_msg_count(&mut self, msg_count: u16) {
+        self.raw_tm[9..11].copy_from_slice(&msg_count.to_be_bytes());
+    }
+
+    /// This function sets the destination ID in the PUS TM secondary header.
+    pub fn set_destination_id(&mut self, dest_id: u16) {
+        self.raw_tm[11..13].copy_from_slice(&dest_id.to_be_bytes())
+    }
+
+    /// Set the sequence count. Returns false and does not update the value if the passed value
+    /// exceeds [MAX_SEQ_COUNT].
+    pub fn set_seq_count(&mut self, seq_count: u16) -> bool {
+        if seq_count > MAX_SEQ_COUNT {
+            return false;
+        }
+        let new_psc =
+            (u16::from_be_bytes(self.raw_tm[2..4].try_into().unwrap()) & 0xC000) | seq_count;
+        self.raw_tm[2..4].copy_from_slice(&new_psc.to_be_bytes());
+        true
+    }
+
+    /// This method has to be called after modifying fields to ensure the CRC16 of the telemetry
+    /// packet remains valid.
+    pub fn finish(self) {
+        let slice_len = self.raw_tm.len();
+        let crc16 = calc_pus_crc16(&self.raw_tm[..slice_len - 2]);
+        self.raw_tm[slice_len - 2..].copy_from_slice(&crc16.to_be_bytes());
+    }
+}
+
+impl SerializablePusPacket for PusTm<'_> {
+    fn len_packed(&self) -> usize {
+        let mut length = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA;
+        if let Some(timestamp) = self.sec_header.timestamp {
+            length += timestamp.len();
+        }
+        if let Some(src_data) = self.source_data {
+            length += src_data.len();
+        }
+        length
+    }
+    /// Write the raw PUS byte representation to a provided buffer.
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
+        let mut curr_idx = 0;
+        let total_size = self.len_packed();
+        if total_size > slice.len() {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: slice.len(),
+                expected: total_size,
+            })
+            .into());
+        }
+        self.sp_header
+            .write_to_be_bytes(&mut slice[0..CCSDS_HEADER_LEN])?;
+        curr_idx += CCSDS_HEADER_LEN;
+        let sec_header_len = size_of::<zc::PusTmSecHeaderWithoutTimestamp>();
+        let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
+        sec_header
+            .write_to_bytes(&mut slice[curr_idx..curr_idx + sec_header_len])
+            .ok_or(ByteConversionError::ZeroCopyToError)?;
+        curr_idx += sec_header_len;
+        if let Some(timestamp) = self.sec_header.timestamp {
+            let timestamp_len = timestamp.len();
+            slice[curr_idx..curr_idx + timestamp_len].copy_from_slice(timestamp);
+            curr_idx += timestamp_len;
+        }
+        if let Some(src_data) = self.source_data {
+            slice[curr_idx..curr_idx + src_data.len()].copy_from_slice(src_data);
+            curr_idx += src_data.len();
+        }
+        let crc16 = crc_procedure(
+            self.calc_crc_on_serialization,
+            &self.crc16,
+            0,
+            curr_idx,
+            slice,
+        )?;
+        slice[curr_idx..curr_idx + 2].copy_from_slice(crc16.to_be_bytes().as_slice());
+        curr_idx += 2;
+        Ok(curr_idx)
+    }
+}
+
+impl PartialEq for PusTm<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.source_data == other.source_data
+    }
 }
 
 //noinspection RsTraitImplementation
@@ -473,33 +580,33 @@ mod tests {
     use crate::ecss::PusVersion::PusC;
     use crate::SpHeader;
 
-    fn base_ping_reply_full_ctor(time_stamp: &[u8]) -> PusTm {
+    fn base_ping_reply_full_ctor(timestamp: &[u8]) -> PusTm {
         let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, &time_stamp);
-        PusTm::new(&mut sph, tc_header, None, true)
+        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, &timestamp);
+        PusTm::new(&mut sph, tm_header, None, true)
     }
 
-    fn base_hk_reply<'a>(time_stamp: &'a [u8], src_data: &'a [u8]) -> PusTm<'a> {
+    fn base_hk_reply<'a>(timestamp: &'a [u8], src_data: &'a [u8]) -> PusTm<'a> {
         let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, &time_stamp);
+        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, &timestamp);
         PusTm::new(&mut sph, tc_header, Some(src_data), true)
     }
 
-    fn dummy_time_stamp() -> &'static [u8] {
+    fn dummy_timestamp() -> &'static [u8] {
         return &[0, 1, 2, 3, 4, 5, 6];
     }
 
     #[test]
     fn test_basic() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
-        verify_ping_reply(&pus_tm, false, 22, dummy_time_stamp());
+        let timestamp = dummy_timestamp();
+        let pus_tm = base_ping_reply_full_ctor(&timestamp);
+        verify_ping_reply(&pus_tm, false, 22, dummy_timestamp());
     }
 
     #[test]
     fn test_serialization_no_source_data() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
+        let timestamp = dummy_timestamp();
+        let pus_tm = base_ping_reply_full_ctor(&timestamp);
         let mut buf: [u8; 32] = [0; 32];
         let ser_len = pus_tm
             .write_to_bytes(&mut buf)
@@ -511,7 +618,7 @@ mod tests {
     #[test]
     fn test_serialization_with_source_data() {
         let src_data = [1, 2, 3];
-        let hk_reply = base_hk_reply(dummy_time_stamp(), &src_data);
+        let hk_reply = base_hk_reply(dummy_timestamp(), &src_data);
         let mut buf: [u8; 32] = [0; 32];
         let ser_len = hk_reply
             .write_to_bytes(&mut buf)
@@ -524,8 +631,8 @@ mod tests {
 
     #[test]
     fn test_setters() {
-        let time_stamp = dummy_time_stamp();
-        let mut pus_tm = base_ping_reply_full_ctor(&time_stamp);
+        let timestamp = dummy_timestamp();
+        let mut pus_tm = base_ping_reply_full_ctor(&timestamp);
         pus_tm.set_sc_time_ref_status(0b1010);
         pus_tm.set_dest_id(0x7fff);
         pus_tm.set_msg_counter(0x1f1f);
@@ -538,8 +645,8 @@ mod tests {
 
     #[test]
     fn test_deserialization_no_source_data() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
+        let timestamp = dummy_timestamp();
+        let pus_tm = base_ping_reply_full_ctor(&timestamp);
         let mut buf: [u8; 32] = [0; 32];
         let ser_len = pus_tm
             .write_to_bytes(&mut buf)
@@ -547,13 +654,13 @@ mod tests {
         assert_eq!(ser_len, 22);
         let (tm_deserialized, size) = PusTm::from_bytes(&buf, 7).expect("Deserialization failed");
         assert_eq!(ser_len, size);
-        verify_ping_reply(&tm_deserialized, false, 22, dummy_time_stamp());
+        verify_ping_reply(&tm_deserialized, false, 22, dummy_timestamp());
     }
 
     #[test]
     fn test_manual_field_update() {
         let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, dummy_time_stamp());
+        let tc_header = PusTmSecondaryHeader::new_simple(17, 2, dummy_timestamp());
         let mut tm = PusTm::new(&mut sph, tc_header, None, false);
         tm.calc_crc_on_serialization = false;
         assert_eq!(tm.data_len(), 0x00);
@@ -573,8 +680,8 @@ mod tests {
 
     #[test]
     fn test_target_buf_too_small() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
+        let timestamp = dummy_timestamp();
+        let pus_tm = base_ping_reply_full_ctor(&timestamp);
         let mut buf: [u8; 16] = [0; 16];
         let res = pus_tm.write_to_bytes(&mut buf);
         assert!(res.is_err());
@@ -597,8 +704,8 @@ mod tests {
     #[test]
     #[cfg(feature = "alloc")]
     fn test_append_to_vec() {
-        let time_stamp = dummy_time_stamp();
-        let pus_tm = base_ping_reply_full_ctor(&time_stamp);
+        let timestamp = dummy_timestamp();
+        let pus_tm = base_ping_reply_full_ctor(&timestamp);
         let mut vec = Vec::new();
         let res = pus_tm.append_to_vec(&mut vec);
         assert!(res.is_ok());
@@ -610,7 +717,7 @@ mod tests {
     #[cfg(feature = "alloc")]
     fn test_append_to_vec_with_src_data() {
         let src_data = [1, 2, 3];
-        let hk_reply = base_hk_reply(dummy_time_stamp(), &src_data);
+        let hk_reply = base_hk_reply(dummy_timestamp(), &src_data);
         let mut vec = Vec::new();
         vec.push(4);
         let res = hk_reply.append_to_vec(&mut vec);
@@ -639,7 +746,7 @@ mod tests {
         assert_eq!(buf[11], 0x00);
         assert_eq!(buf[12], 0x00);
         // Timestamp
-        assert_eq!(&buf[13..20], dummy_time_stamp());
+        assert_eq!(&buf[13..20], dummy_timestamp());
         let mut digest = CRC_CCITT_FALSE.digest();
         digest.update(&buf[0..20]);
         let crc16 = digest.finalize();
@@ -651,14 +758,14 @@ mod tests {
         tm: &PusTm,
         has_user_data: bool,
         exp_full_len: usize,
-        exp_time_stamp: &[u8],
+        exp_timestamp: &[u8],
     ) {
         assert!(tm.is_tm());
         assert_eq!(PusPacket::service(tm), 17);
         assert_eq!(PusPacket::subservice(tm), 2);
         assert!(tm.sec_header_flag());
         assert_eq!(tm.len_packed(), exp_full_len);
-        assert_eq!(tm.time_stamp(), exp_time_stamp);
+        assert_eq!(tm.timestamp().unwrap(), exp_timestamp);
         if has_user_data {
             assert!(!tm.user_data().is_none());
         }
@@ -670,4 +777,45 @@ mod tests {
         assert_eq!(tm.msg_counter(), 0x0000);
         assert_eq!(tm.sc_time_ref_status(), 0b0000);
     }
+
+    #[test]
+    fn partial_eq_pus_tm() {
+        let timestamp = dummy_timestamp();
+        let pus_tm_1 = base_ping_reply_full_ctor(timestamp);
+        let pus_tm_2 = base_ping_reply_full_ctor(timestamp);
+        assert_eq!(pus_tm_1, pus_tm_2);
+    }
+
+    #[test]
+    fn partial_eq_serialized_vs_derialized() {
+        let timestamp = dummy_timestamp();
+        let pus_tm = base_ping_reply_full_ctor(timestamp);
+        let mut buf = [0; 32];
+        pus_tm.write_to_bytes(&mut buf).unwrap();
+        assert_eq!(pus_tm, PusTm::from_bytes(&buf, timestamp.len()).unwrap().0);
+    }
+
+    #[test]
+    fn test_zero_copy_writer() {
+        let ping_tm = base_ping_reply_full_ctor(dummy_timestamp());
+        let mut buf: [u8; 64] = [0; 64];
+        let tm_size = ping_tm
+            .write_to_bytes(&mut buf)
+            .expect("writing PUS ping TM failed");
+        let mut writer = PusTmZeroCopyWriter::new(&mut buf[..tm_size])
+            .expect("Creating zero copy writer failed");
+        writer.set_destination_id(55);
+        writer.set_msg_count(100);
+        writer.set_seq_count(MAX_SEQ_COUNT);
+        writer.set_apid(MAX_APID);
+        writer.finish();
+        // This performs all necessary checks, including the CRC check.
+        let (tm_read_back, tm_size_read_back) =
+            PusTm::from_bytes(&buf, 7).expect("Re-creating PUS TM failed");
+        assert_eq!(tm_size_read_back, tm_size);
+        assert_eq!(tm_read_back.msg_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);
+    }
 }

src/util.rs

@@ -0,0 +1,642 @@
+use crate::{ByteConversionError, SizeMissmatch};
+use core::fmt::{Debug, Display, Formatter};
+#[cfg(feature = "serde")]
+use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;
+
+pub trait ToBeBytes {
+    type ByteArray: AsRef<[u8]>;
+    /// Length when written to big endian bytes.
+    fn written_len(&self) -> usize;
+    fn to_be_bytes(&self) -> Self::ByteArray;
+}
+
+impl ToBeBytes for () {
+    type ByteArray = [u8; 0];
+
+    fn written_len(&self) -> usize {
+        0
+    }
+
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        []
+    }
+}
+
+impl ToBeBytes for u8 {
+    type ByteArray = [u8; 1];
+
+    fn written_len(&self) -> usize {
+        1
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u8::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u16 {
+    type ByteArray = [u8; 2];
+
+    fn written_len(&self) -> usize {
+        2
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u16::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u32 {
+    type ByteArray = [u8; 4];
+
+    fn written_len(&self) -> usize {
+        4
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u32::to_be_bytes(*self)
+    }
+}
+
+impl ToBeBytes for u64 {
+    type ByteArray = [u8; 8];
+
+    fn written_len(&self) -> usize {
+        8
+    }
+    fn to_be_bytes(&self) -> Self::ByteArray {
+        u64::to_be_bytes(*self)
+    }
+}
+
+pub trait UnsignedEnum {
+    /// Size of the unsigned enumeration in bytes.
+    fn size(&self) -> usize;
+    /// Write the unsigned enumeration to a raw buffer. Returns the written size on success.
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError>;
+}
+
+pub trait UnsignedEnumExt: UnsignedEnum + Debug + Copy + Clone + PartialEq + Eq {}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum UnsignedByteFieldError {
+    /// Value is too large for specified width of byte field. The first value contains the width,
+    /// the second value contains the detected value.
+    ValueTooLargeForWidth((usize, u64)),
+    /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
+    /// applicable, for example for conversions.
+    InvalidWidth(usize, Option<usize>),
+    ByteConversionError(ByteConversionError),
+}
+
+impl From<ByteConversionError> for UnsignedByteFieldError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversionError(value)
+    }
+}
+
+impl Display for UnsignedByteFieldError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::ByteConversionError(e) => {
+                write!(f, "low level byte conversion error: {e}")
+            }
+            Self::InvalidWidth(val, _) => {
+                write!(f, "invalid width {val}, only 1, 2, 4 and 8 are allowed.")
+            }
+            Self::ValueTooLargeForWidth((width, value)) => {
+                write!(f, "value {value} too large for width {width}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for UnsignedByteFieldError {}
+
+/// Type erased variant.
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct UnsignedByteField {
+    width: usize,
+    value: u64,
+}
+
+impl UnsignedByteField {
+    pub fn new(width: usize, value: u64) -> Self {
+        Self { width, value }
+    }
+
+    pub fn value(&self) -> u64 {
+        self.value
+    }
+
+    pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, UnsignedByteFieldError> {
+        if width > buf.len() {
+            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                expected: width,
+                found: buf.len(),
+            })
+            .into());
+        }
+        match width {
+            0 => Ok(Self::new(width, 0)),
+            1 => Ok(Self::new(width, buf[0] as u64)),
+            2 => Ok(Self::new(
+                width,
+                u16::from_be_bytes(buf[0..2].try_into().unwrap()) as u64,
+            )),
+            4 => Ok(Self::new(
+                width,
+                u32::from_be_bytes(buf[0..4].try_into().unwrap()) as u64,
+            )),
+            8 => Ok(Self::new(
+                width,
+                u64::from_be_bytes(buf[0..8].try_into().unwrap()),
+            )),
+            _ => Err(UnsignedByteFieldError::InvalidWidth(width, None)),
+        }
+    }
+}
+
+impl UnsignedEnum for UnsignedByteField {
+    fn size(&self) -> usize {
+        self.width
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.size() {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                expected: self.size(),
+                found: buf.len(),
+            }));
+        }
+        match self.size() {
+            0 => Ok(0),
+            1 => {
+                let u8 = UnsignedByteFieldU8::try_from(*self).unwrap();
+                u8.write_to_be_bytes(buf)
+            }
+            2 => {
+                let u16 = UnsignedByteFieldU16::try_from(*self).unwrap();
+                u16.write_to_be_bytes(buf)
+            }
+            4 => {
+                let u32 = UnsignedByteFieldU32::try_from(*self).unwrap();
+                u32.write_to_be_bytes(buf)
+            }
+            8 => {
+                let u64 = UnsignedByteFieldU64::try_from(*self).unwrap();
+                u64.write_to_be_bytes(buf)
+            }
+            _ => {
+                // The API does not allow this.
+                panic!("unexpected written length");
+            }
+        }
+    }
+}
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct GenericUnsignedByteField<TYPE> {
+    value: TYPE,
+}
+
+impl<TYPE> GenericUnsignedByteField<TYPE> {
+    pub fn new(val: TYPE) -> Self {
+        Self { value: val }
+    }
+}
+
+impl<TYPE: ToBeBytes> UnsignedEnum for GenericUnsignedByteField<TYPE> {
+    fn size(&self) -> usize {
+        self.value.written_len()
+    }
+
+    fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.size() {
+            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+                found: buf.len(),
+                expected: self.size(),
+            }));
+        }
+        buf[0..self.size()].copy_from_slice(self.value.to_be_bytes().as_ref());
+        Ok(self.value.written_len())
+    }
+}
+
+pub type UnsignedByteFieldEmpty = GenericUnsignedByteField<()>;
+pub type UnsignedByteFieldU8 = GenericUnsignedByteField<u8>;
+pub type UnsignedByteFieldU16 = GenericUnsignedByteField<u16>;
+pub type UnsignedByteFieldU32 = GenericUnsignedByteField<u32>;
+pub type UnsignedByteFieldU64 = GenericUnsignedByteField<u64>;
+
+pub type UbfU8 = UnsignedByteFieldU8;
+pub type UbfU16 = UnsignedByteFieldU16;
+pub type UbfU32 = UnsignedByteFieldU32;
+pub type UbfU64 = UnsignedByteFieldU64;
+
+impl From<UnsignedByteFieldU8> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU8) -> Self {
+        Self::new(1, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU8 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 1 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(1)));
+        }
+        Ok(Self::new(value.value as u8))
+    }
+}
+
+impl From<UnsignedByteFieldU16> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU16) -> Self {
+        Self::new(2, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU16 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 2 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(2)));
+        }
+        Ok(Self::new(value.value as u16))
+    }
+}
+
+impl From<UnsignedByteFieldU32> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU32) -> Self {
+        Self::new(4, value.value as u64)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU32 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 4 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(4)));
+        }
+        Ok(Self::new(value.value as u32))
+    }
+}
+
+impl From<UnsignedByteFieldU64> for UnsignedByteField {
+    fn from(value: UnsignedByteFieldU64) -> Self {
+        Self::new(8, value.value)
+    }
+}
+
+impl TryFrom<UnsignedByteField> for UnsignedByteFieldU64 {
+    type Error = UnsignedByteFieldError;
+
+    fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
+        if value.width != 8 {
+            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(8)));
+        }
+        Ok(Self::new(value.value))
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+    use crate::util::{
+        UnsignedByteField, UnsignedByteFieldError, UnsignedByteFieldU16, UnsignedByteFieldU32,
+        UnsignedByteFieldU64, UnsignedByteFieldU8, UnsignedEnum,
+    };
+    use crate::ByteConversionError;
+    use std::format;
+
+    #[test]
+    fn test_simple_u8() {
+        let u8 = UnsignedByteFieldU8::new(5);
+        assert_eq!(u8.size(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u8
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 1);
+        assert_eq!(buf[0], 5);
+        for i in 1..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u16() {
+        let u16 = UnsignedByteFieldU16::new(3823);
+        assert_eq!(u16.size(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u16
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 2);
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for i in 2..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u32() {
+        let u32 = UnsignedByteFieldU32::new(80932);
+        assert_eq!(u32.size(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u32
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 4);
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        for i in 4..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn test_simple_u64() {
+        let u64 = UnsignedByteFieldU64::new(5999999);
+        assert_eq!(u64.size(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        let len = u64
+            .write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(len, 8);
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn conversions_u8() {
+        let u8 = UnsignedByteFieldU8::new(5);
+        let u8_type_erased = UnsignedByteField::from(u8);
+        assert_eq!(u8_type_erased.width, 1);
+        assert_eq!(u8_type_erased.value, 5);
+        let u8_conv_back =
+            UnsignedByteFieldU8::try_from(u8_type_erased).expect("conversion failed for u8");
+        assert_eq!(u8, u8_conv_back);
+        assert_eq!(u8_conv_back.value, 5);
+    }
+
+    #[test]
+    fn conversion_u8_fails() {
+        let field = UnsignedByteField::new(2, 60000);
+        let conv_fails = UnsignedByteFieldU8::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 2);
+                assert_eq!(expected, 1);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u16() {
+        let u16 = UnsignedByteFieldU16::new(64444);
+        let u16_type_erased = UnsignedByteField::from(u16);
+        assert_eq!(u16_type_erased.width, 2);
+        assert_eq!(u16_type_erased.value, 64444);
+        let u16_conv_back =
+            UnsignedByteFieldU16::try_from(u16_type_erased).expect("conversion failed for u16");
+        assert_eq!(u16, u16_conv_back);
+        assert_eq!(u16_conv_back.value, 64444);
+    }
+
+    #[test]
+    fn conversion_u16_fails() {
+        let field = UnsignedByteField::new(4, 75000);
+        let conv_fails = UnsignedByteFieldU16::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 4);
+                assert_eq!(expected, 2);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u32() {
+        let u32 = UnsignedByteFieldU32::new(75000);
+        let u32_type_erased = UnsignedByteField::from(u32);
+        assert_eq!(u32_type_erased.width, 4);
+        assert_eq!(u32_type_erased.value, 75000);
+        let u32_conv_back =
+            UnsignedByteFieldU32::try_from(u32_type_erased).expect("conversion failed for u32");
+        assert_eq!(u32, u32_conv_back);
+        assert_eq!(u32_conv_back.value, 75000);
+    }
+
+    #[test]
+    fn conversion_u32_fails() {
+        let field = UnsignedByteField::new(8, 75000);
+        let conv_fails = UnsignedByteFieldU32::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 8);
+                assert_eq!(expected, 4);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn conversions_u64() {
+        let u64 = UnsignedByteFieldU64::new(5999999);
+        let u64_type_erased = UnsignedByteField::from(u64);
+        assert_eq!(u64_type_erased.width, 8);
+        assert_eq!(u64_type_erased.value, 5999999);
+        let u64_conv_back =
+            UnsignedByteFieldU64::try_from(u64_type_erased).expect("conversion failed for u64");
+        assert_eq!(u64, u64_conv_back);
+        assert_eq!(u64_conv_back.value, 5999999);
+    }
+
+    #[test]
+    fn conversion_u64_fails() {
+        let field = UnsignedByteField::new(4, 60000);
+        let conv_fails = UnsignedByteFieldU64::try_from(field);
+        assert!(conv_fails.is_err());
+        let err = conv_fails.unwrap_err();
+        match err {
+            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
+                assert_eq!(width, 4);
+                assert_eq!(expected, 8);
+            }
+            _ => {
+                panic!("{}", format!("invalid error {err}"))
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u8_write() {
+        let u8 = UnsignedByteField::new(1, 5);
+        assert_eq!(u8.size(), 1);
+        let mut buf: [u8; 8] = [0; 8];
+        u8.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        assert_eq!(buf[0], 5);
+        for i in 1..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u16_write() {
+        let u16 = UnsignedByteField::new(2, 3823);
+        assert_eq!(u16.size(), 2);
+        let mut buf: [u8; 8] = [0; 8];
+        u16.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u16::from_be_bytes(buf[0..2].try_into().unwrap());
+        assert_eq!(raw_val, 3823);
+        for i in 2..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u32_write() {
+        let u32 = UnsignedByteField::new(4, 80932);
+        assert_eq!(u32.size(), 4);
+        let mut buf: [u8; 8] = [0; 8];
+        u32.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u32::from_be_bytes(buf[0..4].try_into().unwrap());
+        assert_eq!(raw_val, 80932);
+        for i in 4..8 {
+            assert_eq!(buf[i], 0);
+        }
+    }
+
+    #[test]
+    fn type_erased_u64_write() {
+        let u64 = UnsignedByteField::new(8, 5999999);
+        assert_eq!(u64.size(), 8);
+        let mut buf: [u8; 8] = [0; 8];
+        u64.write_to_be_bytes(&mut buf)
+            .expect("writing to raw buffer failed");
+        let raw_val = u64::from_be_bytes(buf[0..8].try_into().unwrap());
+        assert_eq!(raw_val, 5999999);
+    }
+
+    #[test]
+    fn type_erased_u8_construction() {
+        let buf: [u8; 2] = [5, 10];
+        let u8 = UnsignedByteField::new_from_be_bytes(1, &buf).expect("construction failed");
+        assert_eq!(u8.width, 1);
+        assert_eq!(u8.value, 5);
+    }
+
+    #[test]
+    fn type_erased_u16_construction() {
+        let buf: [u8; 2] = [0x10, 0x15];
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf).expect("construction failed");
+        assert_eq!(u16.width, 2);
+        assert_eq!(u16.value, 0x1015);
+    }
+
+    #[test]
+    fn type_erased_u32_construction() {
+        let buf: [u8; 4] = [0x01, 0x02, 0x03, 0x04];
+        let u32 = UnsignedByteField::new_from_be_bytes(4, &buf).expect("construction failed");
+        assert_eq!(u32.width, 4);
+        assert_eq!(u32.value, 0x01020304);
+    }
+
+    #[test]
+    fn type_erased_u64_construction() {
+        let buf: [u8; 8] = [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08];
+        let u64 = UnsignedByteField::new_from_be_bytes(8, &buf).expect("construction failed");
+        assert_eq!(u64.width, 8);
+        assert_eq!(u64.value, 0x0102030405060708);
+    }
+
+    #[test]
+    fn type_u16_target_buf_too_small() {
+        let u16 = UnsignedByteFieldU16::new(500);
+        let mut buf: [u8; 1] = [0; 1];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall(missmatch) => {
+                assert_eq!(missmatch.found, 1);
+                assert_eq!(missmatch.expected, 2);
+            }
+            _ => {
+                panic!("invalid exception")
+            }
+        }
+    }
+
+    #[test]
+    fn type_erased_u16_target_buf_too_small() {
+        let u16 = UnsignedByteField::new(2, 500);
+        let mut buf: [u8; 1] = [0; 1];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall(missmatch) => {
+                assert_eq!(missmatch.found, 1);
+                assert_eq!(missmatch.expected, 2);
+            }
+            _ => {
+                panic!("invalid exception {}", err)
+            }
+        }
+        let u16 = UnsignedByteField::new_from_be_bytes(2, &buf);
+        assert!(u16.is_err());
+        let err = u16.unwrap_err();
+        if let UnsignedByteFieldError::ByteConversionError(
+            ByteConversionError::FromSliceTooSmall(missmatch),
+        ) = err
+        {
+            assert_eq!(missmatch.expected, 2);
+            assert_eq!(missmatch.found, 1);
+        } else {
+            panic!("unexpected exception {}", err);
+        }
+    }
+
+    #[test]
+    fn type_u32_target_buf_too_small() {
+        let u16 = UnsignedByteFieldU32::new(500);
+        let mut buf: [u8; 3] = [0; 3];
+        let res = u16.write_to_be_bytes(&mut buf);
+        assert!(res.is_err());
+        let err = res.unwrap_err();
+        match err {
+            ByteConversionError::ToSliceTooSmall(missmatch) => {
+                assert_eq!(missmatch.found, 3);
+                assert_eq!(missmatch.expected, 4);
+            }
+            _ => {
+                panic!("invalid exception")
+            }
+        }
+    }
+}