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

Reviewed-on: #29

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.60.0
+          toolchain: 1.61.0
           override: true
           profile: minimal
       - uses: actions-rs/cargo@v1

CHANGELOG.md

@@ -8,6 +8,70 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.7.0-beta.1] 2023-08-28
+
+- Bump `zerocopy` dependency to v0.7.0
+
+## Changed
+
+- The `Tlv` and `Lv` API return `&[u8]` instead of `Option<&[u8]>`.
+- `ByteConversionError` error variants `ToSliceTooSmall` and `FromSliceTooSmall` are struct
+  variants now. `SizeMissmatch` was removed appropriately.
+- `UnsignedByteFieldError` error variants `ValueTooLargeForWidth` and `InvalidWidth` are struct
+  variants now.
+- `TimestampError` error variant `InvalidTimeCode` is struct variant now.
+
+## Added
+
+- Added `raw_data` API for `Tlv` and `Lv` to retrieve the whole `Lv`/`Tlv` slice if the object
+  was created from a raw bytestream.
+- Added `MsgToUserTlv` helper class which wraps a regular `Tlv` and adds some useful functionality.
+- `UnsignedByteField` and `GenericUnsignedByteField` `new` methods are `const` now.
+- `PduError` variants which contained a tuple variant with multiple fields were converted to a
+  struct variant.
+
+# Added
+
+- Added `pdu_datafield_len` getter function for `PduHeader`
+
+## Removed
+
+- `SizeMissmatch` because it is not required for the `ByteConversionError` error enumeration
+  anymore.
+
+# [v0.7.0-beta.0] 2023-08-16
+
+- Moved MSRV from v1.60 to v1.61.
+
+## Changed
+
+- `PusPacket` trait: `user_data` now returns `&[u8]` instead of `Option<&[u8]>`. Empty user data
+  can simply be an empty slice.
+- Moved ECSS TC components from `tc` to `ecss.tc`.
+- Moved ECSS TM components from `tm` to `ecss.tm`.
+- Converted `PusTc` class to more specialized `PusTcCreator` and `PusTcReader`
+  classes. The old `PusTc` class is deprecated now.
+- Converted `PusTm` class to more specialized `PusTmCreator` and `PusTmReader`
+  classes. The old `PusTm` class is deprecated now.
+- Implement `Display` and `Error` for `StdTimestampError` properly.
+- Remove some redundant `Error` suffixes for enum error variants.
+- `CommonPduConfig`: `new_with_defaults` replaced by `new_with_byte_fields`.
+
+## Added
+
+- `source_data` and `app_data` API provided for PUS TM and PUS TC reader classes. These simply
+  call `user_data` but are also in line with the PUS packet standard names for those fields.
+- Added new marker trait `IsPusTelemetry` implemented by `PusTmCreator` and `PusTmReader`.
+- Added new marker trait `IsPusTelecommand` implemented by `PusTcCreator` and `PusTcReader`.
+- `metadata_param` getter method for the `MetadataPdu` object.
+- `Default` impl for CFDP `ChecksumType`
+- `Default` impl for CFDP `CommonPduConfig`
+
+## Fixed
+
+- All `MetadataGenericParam` fields are now public.
+- New setter method `set_source_and_dest_id` for `CommonPduConfig`.
+
 # [v0.6.0] 2023-07-06
 
 ## Added

Cargo.toml

@@ -1,8 +1,8 @@
 [package]
 name = "spacepackets"
-version = "0.6.0"
+version = "0.7.0-beta.1"
 edition = "2021"
-rust-version = "1.60"
+rust-version = "1.61"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]
 description = "Generic implementations for various CCSDS and ECSS packet standards"
 homepage = "https://egit.irs.uni-stuttgart.de/rust/spacepackets"
@@ -13,12 +13,19 @@ categories = ["aerospace", "aerospace::space-protocols", "no-std", "hardware-sup
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-zerocopy = "0.6"
 crc = "3"
 delegate = ">=0.8, <0.11"
 
+[dependencies.zerocopy]
+version = "0.7"
+features = ["derive"]
+
+[dependencies.thiserror]
+version = "1"
+optional = true
+
 [dependencies.num_enum]
-version = "0.6"
+version = ">0.5, <=0.7"
 default-features = false
 
 [dependencies.serde]
@@ -40,7 +47,7 @@ version = "1"
 
 [features]
 default = ["std"]
-std = ["chrono/std", "chrono/clock", "alloc"]
+std = ["chrono/std", "chrono/clock", "alloc", "thiserror"]
 serde = ["dep:serde", "chrono/serde"]
 alloc = ["postcard/alloc", "chrono/alloc"]
 

release-checklist.md

@@ -13,6 +13,10 @@ Checklist for new releases
 6. Wait for CI/CD results for EGit and Github. These also check cross-compilation for bare-metal
    targets.
 
+# Release
+
+1. `cargo publish`
+
 # Post-Release
 
 1. Create a new release on `EGit` based on the release branch.

src/cfdp/lv.rs

@@ -1,6 +1,6 @@
 //! Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
 use crate::cfdp::TlvLvError;
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 use core::str::Utf8Error;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -11,14 +11,26 @@ pub const MIN_LV_LEN: usize = 1;
 
 /// Generic CFDP length-value (LV) abstraction as specified in CFDP 5.1.8.
 ///
+/// Please note that this class is zero-copy and does not generate a copy of the value data for
+/// both the regular [Self::new] constructor and the [Self::from_bytes] constructor.
+///
 /// # Lifetimes
 ///  * `data`: If the LV is generated from a raw bytestream, this will be the lifetime of
 ///    the raw bytestream. If the LV is generated from a raw slice or a similar data reference,
 ///    this will be the lifetime of that data reference.
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct Lv<'data> {
-    data: Option<&'data [u8]>,
+    data: &'data [u8],
+    // If the LV was generated from a raw bytestream, this will contain the start of the
+    // full LV.
+    pub(crate) raw_data: Option<&'data [u8]>,
+}
+
+impl PartialEq for Lv<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.data == other.data
+    }
 }
 
 pub(crate) fn generic_len_check_data_serialization(
@@ -27,10 +39,10 @@ pub(crate) fn generic_len_check_data_serialization(
     min_overhead: usize,
 ) -> Result<(), ByteConversionError> {
     if buf.len() < data_len + min_overhead {
-        return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+        return Err(ByteConversionError::ToSliceTooSmall {
             found: buf.len(),
             expected: data_len + min_overhead,
-        }));
+        });
     }
     Ok(())
 }
@@ -40,10 +52,10 @@ pub(crate) fn generic_len_check_deserialization(
     min_overhead: usize,
 ) -> Result<(), ByteConversionError> {
     if buf.len() < min_overhead {
-        return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+        return Err(ByteConversionError::FromSliceTooSmall {
             found: buf.len(),
             expected: min_overhead,
-        }));
+        });
     }
     Ok(())
 }
@@ -53,12 +65,18 @@ impl<'data> Lv<'data> {
         if data.len() > u8::MAX as usize {
             return Err(TlvLvError::DataTooLarge(data.len()));
         }
-        Ok(Lv { data: Some(data) })
+        Ok(Lv {
+            data,
+            raw_data: None,
+        })
     }
 
     /// Creates a LV with an empty value field.
     pub fn new_empty() -> Lv<'data> {
-        Lv { data: None }
+        Lv {
+            data: &[],
+            raw_data: None,
+        }
     }
 
     /// Helper function to build a string LV. This is especially useful for the file or directory
@@ -70,16 +88,14 @@ impl<'data> Lv<'data> {
     /// Helper function to build a string LV. This is especially useful for the file or directory
     /// path LVs
     #[cfg(feature = "std")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
     pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvError> {
         Self::new(string.as_bytes())
     }
 
     /// Returns the length of the value part, not including the length byte.
     pub fn len_value(&self) -> usize {
-        if self.data.is_none() {
-            return 0;
-        }
-        self.data.unwrap().len()
+        self.data.len()
     }
 
     /// Returns the full raw length, including the length byte.
@@ -89,18 +105,26 @@ impl<'data> Lv<'data> {
 
     /// Checks whether the value field is empty.
     pub fn is_empty(&self) -> bool {
-        self.data.is_none()
+        self.data.len() == 0
     }
 
-    pub fn value(&self) -> Option<&[u8]> {
+    pub fn value(&self) -> &[u8] {
         self.data
     }
 
+    /// If the LV was generated from a raw bytestream using [Self::from_bytes], the raw start
+    /// of the LV can be retrieved with this method.
+    pub fn raw_data(&self) -> Option<&[u8]> {
+        self.raw_data
+    }
+
     /// Convenience function to extract the value as a [str]. This is useful if the LV is
     /// known to contain a [str], for example being a file name.
     pub fn value_as_str(&self) -> Option<Result<&'data str, Utf8Error>> {
-        self.data?;
-        Some(core::str::from_utf8(self.data.unwrap()))
+        if self.is_empty() {
+            return None;
+        }
+        Some(core::str::from_utf8(self.data))
     }
 
     /// Writes the LV to a raw buffer. Please note that the first byte will contain the length
@@ -117,15 +141,14 @@ impl<'data> Lv<'data> {
     }
 
     pub(crate) fn write_to_be_bytes_no_len_check(&self, buf: &mut [u8]) -> usize {
-        if self.data.is_none() {
+        if self.is_empty() {
             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()
+        buf[0] = self.data.len() as u8;
+        buf[MIN_LV_LEN..self.data.len() + MIN_LV_LEN].copy_from_slice(self.data);
+        MIN_LV_LEN + self.data.len()
     }
 
     pub(crate) fn from_be_bytes_no_len_check(
@@ -133,11 +156,10 @@ impl<'data> Lv<'data> {
     ) -> 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 })
+        Ok(Self {
+            data: &buf[MIN_LV_LEN..MIN_LV_LEN + value_len],
+            raw_data: Some(buf),
+        })
     }
 }
 
@@ -154,8 +176,8 @@ pub mod tests {
         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!(lv.value().len() > 0);
+        let val = lv.value();
         assert_eq!(val[0], 1);
         assert_eq!(val[1], 2);
         assert_eq!(val[2], 3);
@@ -171,7 +193,6 @@ pub mod tests {
         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());
@@ -210,10 +231,11 @@ pub mod tests {
         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!(lv.raw_data().is_some());
+        assert_eq!(lv.raw_data().unwrap(), buf);
+        let val = lv.value();
         assert_eq!(val[0], 1);
         assert_eq!(val[1], 2);
         assert_eq!(val[2], 3);
@@ -227,7 +249,6 @@ pub mod tests {
         assert!(lv_empty.is_ok());
         let lv_empty = lv_empty.unwrap();
         assert!(lv_empty.is_empty());
-        assert!(lv_empty.value().is_none());
     }
 
     #[test]
@@ -251,9 +272,9 @@ pub mod tests {
         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);
+        if let ByteConversionError::ToSliceTooSmall { found, expected } = error {
+            assert_eq!(expected, 5);
+            assert_eq!(found, 3);
         } else {
             panic!("invalid error {}", error);
         }
@@ -266,9 +287,9 @@ pub mod tests {
         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);
+        if let ByteConversionError::FromSliceTooSmall { found, expected } = error {
+            assert_eq!(found, 3);
+            assert_eq!(expected, 5);
         } else {
             panic!("invalid error {}", error);
         }
@@ -281,14 +302,14 @@ pub mod tests {
         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);
+        assert_eq!(buf[1], b't');
+        assert_eq!(buf[2], b'e');
+        assert_eq!(buf[3], b's');
+        assert_eq!(buf[4], b't');
+        assert_eq!(buf[5], b'.');
+        assert_eq!(buf[6], b'b');
+        assert_eq!(buf[7], b'i');
+        assert_eq!(buf[8], b'n');
     }
     #[test]
     fn test_str_helper() {

src/cfdp/mod.rs

@@ -134,6 +134,12 @@ pub enum ChecksumType {
     NullChecksum = 15,
 }
 
+impl Default for ChecksumType {
+    fn default() -> Self {
+        Self::NullChecksum
+    }
+}
+
 pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]

src/cfdp/pdu/eof.rs

@@ -4,7 +4,7 @@ use crate::cfdp::pdu::{
 };
 use crate::cfdp::tlv::EntityIdTlv;
 use crate::cfdp::{ConditionCode, CrcFlag, LargeFileFlag};
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
@@ -69,10 +69,10 @@ impl EofPdu {
     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 {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: expected_len,
-            })
+            }
             .into());
         }
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
@@ -106,13 +106,16 @@ impl EofPdu {
         }
         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))
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::EofPdu),
+            }
         })?;
         if directive_type != FileDirectiveType::EofPdu {
-            return Err(PduError::WrongDirectiveType((
-                directive_type,
-                FileDirectiveType::EofPdu,
-            )));
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::EofPdu,
+            });
         }
         current_idx += 1;
         let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)

src/cfdp/pdu/file_data.rs

@@ -3,7 +3,7 @@ use crate::cfdp::pdu::{
     PduError, PduHeader,
 };
 use crate::cfdp::{CrcFlag, LargeFileFlag, PduType, SegmentMetadataFlag};
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -48,10 +48,10 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
 
     pub(crate) fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.written_len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: self.written_len(),
-            }));
+            });
         }
         buf[0] = ((self.record_continuation_state as u8) << 6)
             | self.metadata.map_or(0, |meta| meta.len() as u8);
@@ -63,10 +63,10 @@ impl<'seg_meta> SegmentMetadata<'seg_meta> {
 
     pub(crate) fn from_bytes(buf: &'seg_meta [u8]) -> Result<Self, ByteConversionError> {
         if buf.is_empty() {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: 2,
-            }));
+            });
         }
         let mut metadata = None;
         let seg_metadata_len = (buf[0] & 0b111111) as usize;
@@ -165,10 +165,10 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
 
     pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, PduError> {
         if buf.len() < self.written_len() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: self.written_len(),
-            })
+            }
             .into());
         }
         let mut current_idx = self.pdu_header.write_to_bytes(buf)?;
@@ -207,10 +207,10 @@ impl<'seg_meta, 'file_data> FileDataPdu<'seg_meta, 'file_data> {
         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 {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: current_idx,
                 expected: full_len_without_crc,
-            })
+            }
             .into());
         }
         Ok(Self {
@@ -235,7 +235,7 @@ mod tests {
         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();
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
         let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
         let file_data: [u8; 4] = [1, 2, 3, 4];
         let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
@@ -254,7 +254,7 @@ mod tests {
         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();
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
         let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
         let file_data: [u8; 4] = [1, 2, 3, 4];
         let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
@@ -289,7 +289,7 @@ mod tests {
         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();
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
         let pdu_header = PduHeader::new_for_file_data_default(common_conf, 0);
         let file_data: [u8; 4] = [1, 2, 3, 4];
         let fd_pdu = FileDataPdu::new_no_seg_metadata(pdu_header, 10, &file_data);
@@ -307,7 +307,7 @@ mod tests {
         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();
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
         let pdu_header = PduHeader::new_for_file_data(
             common_conf,
             0,
@@ -372,7 +372,7 @@ mod tests {
         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();
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num).unwrap();
         let pdu_header = PduHeader::new_for_file_data(
             common_conf,
             0,

src/cfdp/pdu/finished.rs

@@ -3,7 +3,7 @@ use crate::cfdp::pdu::{
 };
 use crate::cfdp::tlv::{EntityIdTlv, Tlv, TlvType, TlvTypeField};
 use crate::cfdp::{ConditionCode, CrcFlag, PduType, TlvLvError};
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -136,10 +136,10 @@ impl<'fs_responses> FinishedPdu<'fs_responses> {
     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 {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: expected_len,
-            })
+            }
             .into());
         }
 
@@ -170,13 +170,16 @@ impl<'fs_responses> FinishedPdu<'fs_responses> {
         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))
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::FinishedPdu),
+            }
         })?;
         if directive_type != FileDirectiveType::FinishedPdu {
-            return Err(PduError::WrongDirectiveType((
-                directive_type,
-                FileDirectiveType::FinishedPdu,
-            )));
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::FinishedPdu,
+            });
         }
         current_idx += 1;
         let condition_code = ConditionCode::try_from((buf[current_idx] >> 4) & 0b1111)

src/cfdp/pdu/metadata.rs

@@ -5,18 +5,18 @@ use crate::cfdp::pdu::{
 };
 use crate::cfdp::tlv::Tlv;
 use crate::cfdp::{ChecksumType, CrcFlag, LargeFileFlag, PduType};
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Default, Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub struct MetadataGenericParams {
-    closure_requested: bool,
-    checksum_type: ChecksumType,
-    file_size: u64,
+    pub closure_requested: bool,
+    pub checksum_type: ChecksumType,
+    pub file_size: u64,
 }
 
 impl MetadataGenericParams {
@@ -145,6 +145,10 @@ impl<'src_name, 'dest_name, 'opts> MetadataPdu<'src_name, 'dest_name, 'opts> {
         pdu
     }
 
+    pub fn metadata_params(&self) -> &MetadataGenericParams {
+        &self.metadata_params
+    }
+
     pub fn src_file_name(&self) -> Lv<'src_name> {
         self.src_file_name
     }
@@ -197,10 +201,10 @@ impl<'src_name, 'dest_name, 'opts> MetadataPdu<'src_name, 'dest_name, 'opts> {
     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 {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: expected_len,
-            })
+            }
             .into());
         }
 
@@ -244,13 +248,16 @@ impl<'src_name, 'dest_name, 'opts> MetadataPdu<'src_name, 'dest_name, 'opts> {
         }
         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))
+            PduError::InvalidDirectiveType {
+                found: buf[current_idx],
+                expected: Some(FileDirectiveType::MetadataPdu),
+            }
         })?;
         if directive_type != FileDirectiveType::MetadataPdu {
-            return Err(PduError::WrongDirectiveType((
-                directive_type,
-                FileDirectiveType::MetadataPdu,
-            )));
+            return Err(PduError::WrongDirectiveType {
+                found: directive_type,
+                expected: FileDirectiveType::MetadataPdu,
+            });
         }
         current_idx += 1;
         let (fss_len, file_size) =

src/cfdp/pdu/mod.rs

@@ -1,8 +1,8 @@
 //! CFDP Packet Data Unit (PDU) support.
 use crate::cfdp::*;
-use crate::util::{UnsignedByteField, UnsignedEnum};
+use crate::util::{UnsignedByteField, UnsignedByteFieldU8, UnsignedEnum};
+use crate::ByteConversionError;
 use crate::CRC_CCITT_FALSE;
-use crate::{ByteConversionError, SizeMissmatch};
 use core::fmt::{Display, Formatter};
 #[cfg(feature = "std")]
 use std::error::Error;
@@ -35,16 +35,19 @@ pub enum PduError {
     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)),
+    SourceDestIdLenMissmatch {
+        src_id_len: usize,
+        dest_id_len: usize,
+    },
+    WrongDirectiveType {
+        found: FileDirectiveType,
+        expected: FileDirectiveType,
+    },
     /// The directive type field contained a value not in the range of permitted values.
-    /// The first tuple entry will be the found raw number, the second entry the expected entry
-    /// type.
-    InvalidDirectiveType((u8, FileDirectiveType)),
+    InvalidDirectiveType {
+        found: u8,
+        expected: Option<FileDirectiveType>,
+    },
     /// Invalid condition code. Contains the raw detected value.
     InvalidConditionCode(u8),
     /// Invalid checksum type which is not part of the checksums listed in the
@@ -80,10 +83,13 @@ impl Display for PduError {
                     "cfdp version missmatch, found {raw}, expected {CFDP_VERSION_2}"
                 )
             }
-            PduError::SourceDestIdLenMissmatch((src_len, dest_len)) => {
+            PduError::SourceDestIdLenMissmatch {
+                src_id_len,
+                dest_id_len,
+            } => {
                 write!(
                     f,
-                    "missmatch of PDU source length {src_len} and destination length {dest_len}"
+                    "missmatch of PDU source length {src_id_len} and destination length {dest_id_len}"
                 )
             }
             PduError::ByteConversionError(e) => {
@@ -92,17 +98,16 @@ impl Display for PduError {
             PduError::FileSizeTooLarge(value) => {
                 write!(f, "file size value {value} exceeds allowed 32 bit width")
             }
-            PduError::WrongDirectiveType((found, expected)) => {
+            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)) => {
+            PduError::InvalidDirectiveType { found, expected } => {
                 write!(
                     f,
-                    "invalid directive type value {found}, expected {expected:?} ({})",
-                    *expected as u8
+                    "invalid directive type value {found}, expected {expected:?}"
                 )
             }
             PduError::InvalidChecksumType(checksum_type) => {
@@ -168,22 +173,8 @@ impl CommonPduConfig {
         crc_flag: CrcFlag,
         direction: Direction,
     ) -> Result<Self, PduError> {
-        let source_id = source_id.into();
-        let dest_id = dest_id.into();
+        let (source_id, dest_id) = Self::source_dest_id_check(source_id, dest_id)?;
         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
@@ -204,7 +195,7 @@ impl CommonPduConfig {
         })
     }
 
-    pub fn new_with_defaults(
+    pub fn new_with_byte_fields(
         source_id: impl Into<UnsignedByteField>,
         dest_id: impl Into<UnsignedByteField>,
         transaction_seq_num: impl Into<UnsignedByteField>,
@@ -224,11 +215,62 @@ impl CommonPduConfig {
         self.source_entity_id
     }
 
+    fn source_dest_id_check(
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+    ) -> Result<(UnsignedByteField, UnsignedByteField), PduError> {
+        let source_id = source_id.into();
+        let dest_id = dest_id.into();
+        if source_id.size() != dest_id.size() {
+            return Err(PduError::SourceDestIdLenMissmatch {
+                src_id_len: source_id.size(),
+                dest_id_len: dest_id.size(),
+            });
+        }
+        if source_id.size() != 1
+            && source_id.size() != 2
+            && source_id.size() != 4
+            && source_id.size() != 8
+        {
+            return Err(PduError::InvalidEntityLen(source_id.size() as u8));
+        }
+        Ok((source_id, dest_id))
+    }
+
+    pub fn set_source_and_dest_id(
+        &mut self,
+        source_id: impl Into<UnsignedByteField>,
+        dest_id: impl Into<UnsignedByteField>,
+    ) -> Result<(), PduError> {
+        let (source_id, dest_id) = Self::source_dest_id_check(source_id, dest_id)?;
+        self.source_entity_id = source_id;
+        self.dest_entity_id = dest_id;
+        Ok(())
+    }
+
     pub fn dest_id(&self) -> UnsignedByteField {
         self.dest_entity_id
     }
 }
 
+impl Default for CommonPduConfig {
+    /// The defaults for the source ID, destination ID and the transaction sequence number is the
+    /// [UnsignedByteFieldU8] with an intitial value of 0
+    fn default() -> Self {
+        // The new function can not fail for these input parameters.
+        Self::new(
+            UnsignedByteFieldU8::new(0),
+            UnsignedByteFieldU8::new(0),
+            UnsignedByteFieldU8::new(0),
+            TransmissionMode::Acknowledged,
+            LargeFileFlag::Normal,
+            CrcFlag::NoCrc,
+            Direction::TowardsReceiver,
+        )
+        .unwrap()
+    }
+}
+
 pub const FIXED_HEADER_LEN: usize = 4;
 
 /// Abstraction for the PDU header common to all CFDP PDUs.
@@ -303,6 +345,10 @@ impl PduHeader {
             + self.pdu_conf.dest_entity_id.size()
     }
 
+    pub fn pdu_datafield_len(&self) -> usize {
+        self.pdu_datafield_len.into()
+    }
+
     /// Returns the full length of the PDU when written to a raw buffer, which is the header length
     /// plus the PDU datafield length.
     pub fn pdu_len(&self) -> usize {
@@ -313,20 +359,20 @@ impl PduHeader {
         // 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(),
-            )));
+            return Err(PduError::SourceDestIdLenMissmatch {
+                src_id_len: self.pdu_conf.source_entity_id.size(),
+                dest_id_len: self.pdu_conf.dest_entity_id.size(),
+            });
         }
         if buf.len()
             < FIXED_HEADER_LEN
                 + self.pdu_conf.source_entity_id.size()
                 + self.pdu_conf.transaction_seq_num.size()
         {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: FIXED_HEADER_LEN,
-            })
+            }
             .into());
         }
         let mut current_idx = 0;
@@ -367,10 +413,10 @@ impl PduHeader {
     /// 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 {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: self.pdu_len(),
-            })
+            }
             .into());
         }
         if self.pdu_conf.crc_flag == CrcFlag::WithCrc {
@@ -397,10 +443,10 @@ impl PduHeader {
     pub fn from_bytes(buf: &[u8]) -> Result<(Self, usize), PduError> {
         if buf.len() < FIXED_HEADER_LEN {
             return Err(PduError::ByteConversionError(
-                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+                ByteConversionError::FromSliceTooSmall {
                     found: buf.len(),
                     expected: FIXED_HEADER_LEN,
-                }),
+                },
             ));
         }
         let cfdp_version_raw = (buf[0] >> 5) & 0b111;
@@ -435,10 +481,10 @@ impl PduHeader {
             ));
         }
         if buf.len() < (4 + 2 * expected_len_entity_ids + expected_len_seq_num) {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: 4 + 2 * expected_len_entity_ids + expected_len_seq_num,
-            })
+            }
             .into());
         }
         let mut current_idx = 4;
@@ -534,17 +580,17 @@ pub(crate) fn generic_length_checks_pdu_deserialization(
 ) -> Result<(), ByteConversionError> {
     // Buffer too short to hold additional expected minimum datasize.
     if buf.len() < min_expected_len {
-        return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+        return Err(ByteConversionError::FromSliceTooSmall {
             found: buf.len(),
             expected: min_expected_len,
-        }));
+        });
     }
     // This can happen if the PDU datafield length value is invalid.
     if full_len_without_crc < min_expected_len {
-        return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+        return Err(ByteConversionError::FromSliceTooSmall {
             found: full_len_without_crc,
             expected: min_expected_len,
-        }));
+        });
     }
     Ok(())
 }
@@ -574,8 +620,9 @@ mod tests {
         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");
+        let mut pdu_conf =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_num)
+                .expect("Generating common PDU config");
         pdu_conf.crc_flag = crc_flag;
         pdu_conf.file_flag = fss;
         pdu_conf
@@ -647,7 +694,7 @@ mod tests {
         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)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         assert_eq!(pdu_header.pdu_type(), PduType::FileDirective);
@@ -666,12 +713,43 @@ mod tests {
         assert_eq!(pdu_header.header_len(), 7);
     }
 
+    #[test]
+    fn test_basic_state_default() {
+        let default_conf = CommonPduConfig::default();
+        assert_eq!(default_conf.source_id(), UnsignedByteFieldU8::new(0).into());
+        assert_eq!(default_conf.dest_id(), UnsignedByteFieldU8::new(0).into());
+        assert_eq!(
+            default_conf.transaction_seq_num,
+            UnsignedByteFieldU8::new(0).into()
+        );
+        assert_eq!(default_conf.trans_mode, TransmissionMode::Acknowledged);
+        assert_eq!(default_conf.direction, Direction::TowardsReceiver);
+        assert_eq!(default_conf.crc_flag, CrcFlag::NoCrc);
+        assert_eq!(default_conf.file_flag, LargeFileFlag::Normal);
+    }
+
+    #[test]
+    fn test_pdu_header_setter() {
+        let src_id = UnsignedByteFieldU8::new(1);
+        let dest_id = UnsignedByteFieldU8::new(2);
+        let transaction_id = UnsignedByteFieldU8::new(3);
+        let mut common_pdu_cfg =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
+                .expect("common config creation failed");
+        let other_src_id = UnsignedByteFieldU16::new(5);
+        let other_dest_id = UnsignedByteFieldU16::new(6);
+        let set_result = common_pdu_cfg.set_source_and_dest_id(other_src_id, other_dest_id);
+        assert!(set_result.is_ok());
+        assert_eq!(common_pdu_cfg.source_id(), other_src_id.into());
+        assert_eq!(common_pdu_cfg.dest_id(), other_dest_id.into());
+    }
+
     #[test]
     fn test_serialization_1() {
         let src_id = UnsignedByteFieldU8::new(1);
         let dest_id = UnsignedByteFieldU8::new(2);
         let transaction_id = UnsignedByteFieldU8::new(3);
-        let common_pdu_cfg = CommonPduConfig::new_with_defaults(src_id, dest_id, transaction_id)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
@@ -687,7 +765,7 @@ mod tests {
         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)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
@@ -706,7 +784,7 @@ mod tests {
         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)
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
                 .expect("common config creation failed");
         common_pdu_cfg.crc_flag = CrcFlag::WithCrc;
         common_pdu_cfg.direction = Direction::TowardsSender;
@@ -733,7 +811,7 @@ mod tests {
         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)
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
                 .expect("common config creation failed");
         common_pdu_cfg.crc_flag = CrcFlag::WithCrc;
         common_pdu_cfg.direction = Direction::TowardsSender;
@@ -760,7 +838,7 @@ mod tests {
         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)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
@@ -784,11 +862,13 @@ mod tests {
         let res = PduHeader::from_bytes(&buf);
         assert!(res.is_err());
         let error = res.unwrap_err();
-        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall(missmatch)) =
-            error
+        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall {
+            found,
+            expected,
+        }) = error
         {
-            assert_eq!(missmatch.found, 3);
-            assert_eq!(missmatch.expected, FIXED_HEADER_LEN);
+            assert_eq!(found, 3);
+            assert_eq!(expected, FIXED_HEADER_LEN);
         } else {
             panic!("invalid exception: {}", error);
         }
@@ -799,7 +879,7 @@ mod tests {
         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)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
@@ -808,11 +888,13 @@ mod tests {
         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
+        if let PduError::ByteConversionError(ByteConversionError::FromSliceTooSmall {
+            found,
+            expected,
+        }) = error
         {
-            assert_eq!(missmatch.found, 6);
-            assert_eq!(missmatch.expected, 7);
+            assert_eq!(found, 6);
+            assert_eq!(expected, 7);
         }
     }
 
@@ -822,7 +904,8 @@ mod tests {
         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);
+        let pdu_conf_res =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, invalid_byte_field);
         assert!(pdu_conf_res.is_err());
         let error = pdu_conf_res.unwrap_err();
         if let PduError::InvalidTransactionSeqNumLen(len) = error {
@@ -830,7 +913,7 @@ mod tests {
         } else {
             panic!("Invalid exception: {}", error)
         }
-        let pdu_conf_res = CommonPduConfig::new_with_defaults(
+        let pdu_conf_res = CommonPduConfig::new_with_byte_fields(
             invalid_byte_field,
             invalid_byte_field,
             transaction_seq_id,
@@ -848,12 +931,17 @@ mod tests {
         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);
+        let pdu_conf_res =
+            CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_seq_id);
         assert!(pdu_conf_res.is_err());
         let error = pdu_conf_res.unwrap_err();
-        if let PduError::SourceDestIdLenMissmatch((src_len, dest_len)) = error {
-            assert_eq!(src_len, 1);
-            assert_eq!(dest_len, 2);
+        if let PduError::SourceDestIdLenMissmatch {
+            src_id_len,
+            dest_id_len,
+        } = error
+        {
+            assert_eq!(src_id_len, 1);
+            assert_eq!(dest_id_len, 2);
         }
     }
 
@@ -862,7 +950,7 @@ mod tests {
         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)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];
@@ -886,7 +974,7 @@ mod tests {
         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)
+        let common_pdu_cfg = CommonPduConfig::new_with_byte_fields(src_id, dest_id, transaction_id)
             .expect("common config creation failed");
         let pdu_header = PduHeader::new_no_file_data(common_pdu_cfg, 5);
         let mut buf: [u8; 7] = [0; 7];

src/cfdp/tlv/mod.rs

@@ -4,11 +4,13 @@ use crate::cfdp::lv::{
 };
 use crate::cfdp::TlvLvError;
 use crate::util::{UnsignedByteField, UnsignedByteFieldError, UnsignedEnum};
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
 
+pub mod msg_to_user;
+
 pub const MIN_TLV_LEN: usize = 2;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
@@ -70,6 +72,9 @@ impl From<TlvTypeField> for u8 {
 
 /// Generic CFDP type-length-value (TLV) abstraction as specified in CFDP 5.1.9.
 ///
+/// Please note that this class is zero-copy and does not generate a copy of the value data for
+/// both the regular [Self::new] constructor and the [Self::from_bytes] constructor.
+///
 /// # Lifetimes
 ///  * `data`: If the TLV is generated from a raw bytestream, this will be the lifetime of
 ///    the raw bytestream. If the TLV is generated from a raw slice or a similar data reference,
@@ -98,22 +103,41 @@ impl<'data> Tlv<'data> {
         }
     }
 
+    /// Checks whether the type field contains one of the standard types specified in the CFDP
+    /// standard and is part of the [TlvType] enum.
+    pub fn is_standard_tlv(&self) -> bool {
+        if let TlvTypeField::Standard(_) = self.tlv_type_field {
+            return true;
+        }
+        false
+    }
+
+    /// Returns the standard TLV type if the TLV field is not a custom field
+    pub fn tlv_type(&self) -> Option<TlvType> {
+        if let TlvTypeField::Standard(tlv_type) = self.tlv_type_field {
+            Some(tlv_type)
+        } else {
+            None
+        }
+    }
+
     pub fn tlv_type_field(&self) -> TlvTypeField {
         self.tlv_type_field
     }
 
     pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
-        generic_len_check_data_serialization(buf, self.len_value(), MIN_TLV_LEN)?;
+        generic_len_check_data_serialization(buf, self.value().len(), MIN_TLV_LEN)?;
         buf[0] = self.tlv_type_field.into();
         self.lv.write_to_be_bytes_no_len_check(&mut buf[1..]);
         Ok(self.len_full())
     }
 
-    pub fn value(&self) -> Option<&[u8]> {
+    pub fn value(&self) -> &[u8] {
         self.lv.value()
     }
 
-    /// Returns the length of the value part, not including the length byte.
+    /// Helper method to retrieve the length of the value. Simply calls the [slice::len] method of
+    /// [Self::value]
     pub fn len_value(&self) -> usize {
         self.lv.len_value()
     }
@@ -134,10 +158,20 @@ impl<'data> Tlv<'data> {
     /// [Self::len_full].
     pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
         generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
-        Ok(Self {
+        let mut tlv = Self {
             tlv_type_field: TlvTypeField::from(buf[0]),
             lv: Lv::from_bytes(&buf[MIN_LV_LEN..])?,
-        })
+        };
+        // We re-use this field so we do not need an additional struct field to store the raw start
+        // of the TLV.
+        tlv.lv.raw_data = Some(buf);
+        Ok(tlv)
+    }
+
+    /// If the TLV was generated from a raw bytestream using [Self::from_bytes], the raw start
+    /// of the TLV can be retrieved with this method.
+    pub fn raw_data(&self) -> Option<&[u8]> {
+        self.lv.raw_data()
     }
 }
 
@@ -166,10 +200,10 @@ impl EntityIdTlv {
 
     fn len_check(buf: &[u8]) -> Result<(), ByteConversionError> {
         if buf.len() < 2 {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: 2,
-            }));
+            });
         }
         Ok(())
     }
@@ -234,21 +268,19 @@ impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
                 )));
             }
         }
-        if value.len_value() != 1
-            && value.len_value() != 2
-            && value.len_value() != 4
-            && value.len_value() != 8
-        {
-            return Err(TlvLvError::InvalidValueLength(value.len_value()));
+        let len_value = value.value().len();
+        if len_value != 1 && len_value != 2 && len_value != 4 && len_value != 8 {
+            return Err(TlvLvError::InvalidValueLength(len_value));
         }
         Ok(Self::new(
-            UnsignedByteField::new_from_be_bytes(value.len_value(), value.value().unwrap())
-                .map_err(|e| match e {
+            UnsignedByteField::new_from_be_bytes(len_value, value.value()).map_err(
+                |e| match e {
                     UnsignedByteFieldError::ByteConversionError(e) => e,
                     // This can not happen, we checked for the length validity, and the data is always smaller than
                     // 255 bytes.
                     _ => panic!("unexpected error"),
-                })?,
+                },
+            )?,
         ))
     }
 }
@@ -390,10 +422,10 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
 
     pub fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.len_full() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: self.len_full(),
-            }));
+            });
         }
         buf[0] = TlvType::FilestoreRequest as u8;
         buf[1] = self.len_value() as u8;
@@ -417,10 +449,10 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
         buf: &'longest [u8],
     ) -> Result<Self, TlvLvError> {
         if buf.len() < 2 {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: 2,
-            })
+            }
             .into());
         }
         verify_tlv_type(buf[0], TlvType::FilestoreRequest)?;
@@ -454,8 +486,8 @@ mod tests {
     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";
+    const TLV_TEST_STR_0: &str = "hello.txt";
+    const TLV_TEST_STR_1: &str = "hello2.txt";
 
     #[test]
     fn test_basic() {
@@ -470,10 +502,10 @@ mod tests {
             TlvTypeField::Standard(TlvType::EntityId)
         );
         assert_eq!(tlv_res.len_full(), 3);
+        assert_eq!(tlv_res.value().len(), 1);
         assert_eq!(tlv_res.len_value(), 1);
         assert!(!tlv_res.is_empty());
-        assert!(tlv_res.value().is_some());
-        assert_eq!(tlv_res.value().unwrap()[0], 5);
+        assert_eq!(tlv_res.value()[0], 5);
     }
 
     #[test]
@@ -498,26 +530,27 @@ mod tests {
         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);
+        let tlv_from_raw = Tlv::from_bytes(&buf);
         assert!(tlv_from_raw.is_ok());
         let tlv_from_raw = tlv_from_raw.unwrap();
+        assert!(tlv_from_raw.raw_data().is_some());
+        assert_eq!(tlv_from_raw.raw_data().unwrap(), buf);
         assert_eq!(
             tlv_from_raw.tlv_type_field(),
             TlvTypeField::Standard(TlvType::EntityId)
         );
-        assert_eq!(tlv_from_raw.len_value(), 1);
+        assert_eq!(tlv_from_raw.value().len(), 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);
+        assert_eq!(tlv_from_raw.value()[0], 5);
     }
 
     #[test]
     fn test_empty() {
         let tlv_empty = Tlv::new_empty(TlvType::MsgToUser);
-        assert!(tlv_empty.value().is_none());
+        assert_eq!(tlv_empty.value().len(), 0);
         assert!(tlv_empty.is_empty());
         assert_eq!(tlv_empty.len_full(), 2);
-        assert_eq!(tlv_empty.len_value(), 0);
+        assert!(tlv_empty.value().is_empty());
         assert_eq!(
             tlv_empty.tlv_type_field(),
             TlvTypeField::Standard(TlvType::MsgToUser)
@@ -538,17 +571,17 @@ mod tests {
         let mut buf: [u8; 4] = [0; 4];
         buf[0] = TlvType::MsgToUser as u8;
         buf[1] = 0;
-        let tlv_empty = Tlv::from_bytes(&mut buf);
+        let tlv_empty = Tlv::from_bytes(&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.value().len(), 0);
         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);
+        assert!(tlv_empty.value().is_empty());
     }
 
     #[test]
@@ -570,11 +603,11 @@ mod tests {
         buf[0] = 3;
         buf[1] = 1;
         buf[2] = 5;
-        let tlv = Tlv::from_bytes(&mut buf);
+        let tlv = Tlv::from_bytes(&buf);
         assert!(tlv.is_ok());
         let tlv = tlv.unwrap();
         assert_eq!(tlv.tlv_type_field(), TlvTypeField::Custom(3));
-        assert_eq!(tlv.len_value(), 1);
+        assert_eq!(tlv.value().len(), 1);
         assert_eq!(tlv.len_full(), 3);
     }
 

src/cfdp/tlv/msg_to_user.rs

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

src/ecss/mod.rs

@@ -1,8 +1,8 @@
 //! Common definitions and helpers required to create PUS TMTC packets according to
 //! [ECSS-E-ST-70-41C](https://ecss.nl/standard/ecss-e-st-70-41c-space-engineering-telemetry-and-telecommand-packet-utilization-15-april-2016/)
 //!
-//! You can find the PUS telecommand definitions in the [crate::tc] module and ithe PUS telemetry definitions
-//! inside the [crate::tm] module.
+//! You can find the PUS telecommand definitions in the [tc] module and ithe PUS telemetry definitions
+//! inside the [tm] module.
 use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
 use core::fmt::{Debug, Display, Formatter};
 use core::mem::size_of;
@@ -15,6 +15,8 @@ use std::error::Error;
 pub mod event;
 pub mod hk;
 pub mod scheduling;
+pub mod tc;
+pub mod tm;
 pub mod verification;
 
 pub type CrcType = u16;
@@ -149,7 +151,7 @@ pub enum PusError {
     NoRawData,
     /// CRC16 needs to be calculated first
     CrcCalculationMissing,
-    ByteConversionError(ByteConversionError),
+    ByteConversion(ByteConversionError),
 }
 
 impl Display for PusError {
@@ -173,7 +175,7 @@ impl Display for PusError {
             PusError::CrcCalculationMissing => {
                 write!(f, "crc16 was not calculated")
             }
-            PusError::ByteConversionError(e) => {
+            PusError::ByteConversion(e) => {
                 write!(f, "low level byte conversion error: {e}")
             }
         }
@@ -183,7 +185,7 @@ impl Display for PusError {
 #[cfg(feature = "std")]
 impl Error for PusError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
-        if let PusError::ByteConversionError(e) = self {
+        if let PusError::ByteConversion(e) = self {
             return Some(e);
         }
         None
@@ -192,7 +194,7 @@ impl Error for PusError {
 
 impl From<ByteConversionError> for PusError {
     fn from(e: ByteConversionError) -> Self {
-        PusError::ByteConversionError(e)
+        PusError::ByteConversion(e)
     }
 }
 
@@ -204,8 +206,7 @@ pub trait PusPacket: CcsdsPacket {
     fn pus_version(&self) -> PusVersion;
     fn service(&self) -> u8;
     fn subservice(&self) -> u8;
-
-    fn user_data(&self) -> Option<&[u8]>;
+    fn user_data(&self) -> &[u8];
     fn crc16(&self) -> Option<u16>;
 }
 
@@ -249,11 +250,10 @@ pub(crate) fn user_data_from_raw(
     total_len: usize,
     raw_data_len: usize,
     slice: &[u8],
-) -> Result<Option<&[u8]>, PusError> {
+) -> Result<&[u8], PusError> {
     match current_idx {
-        _ if current_idx == total_len - 2 => Ok(None),
         _ if current_idx > total_len - 2 => Err(PusError::RawDataTooShort(raw_data_len)),
-        _ => Ok(Some(&slice[current_idx..total_len - 2])),
+        _ => Ok(&slice[current_idx..total_len - 2]),
     }
 }
 
@@ -397,9 +397,9 @@ mod tests {
         assert!(res.is_err());
         let error = res.unwrap_err();
         match error {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.expected, 2);
-                assert_eq!(missmatch.found, 1);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(expected, 2);
+                assert_eq!(found, 1);
             }
             _ => {
                 panic!("Unexpected error {:?}", error);
@@ -428,9 +428,9 @@ mod tests {
         assert!(res.is_err());
         let error = res.unwrap_err();
         match error {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.expected, 4);
-                assert_eq!(missmatch.found, 3);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(expected, 4);
+                assert_eq!(found, 3);
             }
             _ => {
                 panic!("Unexpected error {:?}", error);

src/ecss/tc.rs

@@ -5,13 +5,13 @@
 //!
 //! ```rust
 //! use spacepackets::{CcsdsPacket, SpHeader};
-//! use spacepackets::tc::{PusTc, PusTcSecondaryHeader};
 //! use spacepackets::ecss::{PusPacket, SerializablePusPacket};
+//! use spacepackets::ecss::tc::{PusTcCreator, PusTcReader, PusTcSecondaryHeader};
 //!
 //! // Create a ping telecommand with no user application data
 //! let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
 //! let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
-//! let pus_tc = PusTc::new(&mut sph, tc_header, None, true);
+//! let pus_tc = PusTcCreator::new(&mut sph, tc_header, None, true);
 //! println!("{:?}", pus_tc);
 //! assert_eq!(pus_tc.service(), 17);
 //! assert_eq!(pus_tc.subservice(), 1);
@@ -26,19 +26,17 @@
 //! println!("{:?}", &test_buf[0..size]);
 //!
 //! // Deserialize from the raw byte representation
-//! let pus_tc_deserialized = PusTc::from_bytes(&test_buf).expect("Deserialization failed");
+//! let pus_tc_deserialized = PusTcReader::new(&test_buf).expect("Deserialization failed");
 //! assert_eq!(pus_tc.service(), 17);
 //! assert_eq!(pus_tc.subservice(), 1);
 //! assert_eq!(pus_tc.apid(), 0x02);
 //! ```
 use crate::ecss::{
-    ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
+    ccsds_impl, crc_from_raw_data, 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, CCSDS_HEADER_LEN,
-};
+use crate::{ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, CCSDS_HEADER_LEN};
 use crate::{SpHeader, CRC_CCITT_FALSE};
 use core::mem::size_of;
 use delegate::delegate;
@@ -49,12 +47,17 @@ use zerocopy::AsBytes;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
 
+pub use legacy_tc::*;
+
 /// PUS C secondary header length is fixed
 pub const PUC_TC_SECONDARY_HEADER_LEN: usize = size_of::<zc::PusTcSecondaryHeader>();
 pub const PUS_TC_MIN_LEN_WITHOUT_APP_DATA: usize =
     CCSDS_HEADER_LEN + PUC_TC_SECONDARY_HEADER_LEN + size_of::<CrcType>();
 const PUS_VERSION: PusVersion = PusVersion::PusC;
 
+/// Marker trait for PUS telecommand structures.
+pub trait IsPusTelecommand {}
+
 #[derive(Copy, Clone, PartialEq, Debug)]
 enum AckOpts {
     Acceptance = 0b1000,
@@ -77,11 +80,11 @@ pub trait GenericPusTcSecondaryHeader {
 }
 
 pub mod zc {
+    use crate::ecss::tc::GenericPusTcSecondaryHeader;
     use crate::ecss::{PusError, PusVersion};
-    use crate::tc::GenericPusTcSecondaryHeader;
-    use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, NetworkEndian, Unaligned, U16};
 
-    #[derive(FromBytes, AsBytes, Unaligned)]
+    #[derive(FromZeroes, FromBytes, AsBytes, Unaligned)]
     #[repr(C)]
     pub struct PusTcSecondaryHeader {
         version_ack: u8,
@@ -90,9 +93,9 @@ pub mod zc {
         source_id: U16<NetworkEndian>,
     }
 
-    impl TryFrom<crate::tc::PusTcSecondaryHeader> for PusTcSecondaryHeader {
+    impl TryFrom<crate::ecss::tc::PusTcSecondaryHeader> for PusTcSecondaryHeader {
         type Error = PusError;
-        fn try_from(value: crate::tc::PusTcSecondaryHeader) -> Result<Self, Self::Error> {
+        fn try_from(value: crate::ecss::tc::PusTcSecondaryHeader) -> Result<Self, Self::Error> {
             if value.version != PusVersion::PusC {
                 return Err(PusError::VersionNotSupported(value.version));
             }
@@ -206,35 +209,342 @@ impl PusTcSecondaryHeader {
     }
 }
 
-/// 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.
+pub mod legacy_tc {
+    use crate::ecss::tc::{
+        zc, GenericPusTcSecondaryHeader, IsPusTelecommand, PusTcSecondaryHeader, ACK_ALL,
+        PUC_TC_SECONDARY_HEADER_LEN, PUS_TC_MIN_LEN_WITHOUT_APP_DATA,
+    };
+    use crate::ecss::{
+        ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls,
+        verify_crc16_ccitt_false_from_raw_to_pus_error, PusError, PusPacket, SerializablePusPacket,
+        CCSDS_HEADER_LEN,
+    };
+    use crate::ecss::{user_data_from_raw, PusVersion};
+    use crate::SequenceFlags;
+    use crate::{ByteConversionError, CcsdsPacket, PacketType, SpHeader, CRC_CCITT_FALSE};
+    use core::mem::size_of;
+    use delegate::delegate;
+    use zerocopy::AsBytes;
+
+    #[cfg(feature = "alloc")]
+    use alloc::vec::Vec;
+
+    #[cfg(feature = "serde")]
+    use serde::{Deserialize, Serialize};
+
+    /// 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.
+    ///
+    /// # 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<'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<&'raw_data [u8]>,
+        app_data: &'raw_data [u8],
+        crc16: Option<u16>,
+    }
+
+    impl<'raw_data> PusTc<'raw_data> {
+        /// Generates a new struct instance.
+        ///
+        /// # Arguments
+        ///
+        /// * `sp_header` - Space packet header information. The correct packet type will be set
+        ///     automatically
+        /// * `sec_header` - Information contained in the data field header, including the service
+        ///     and subservice type
+        /// * `app_data` - Custom application data
+        /// * `set_ccsds_len` - Can be used to automatically update the CCSDS space packet data length
+        ///     field. If this is not set to true, [PusTc::update_ccsds_data_len] can be called to set
+        ///     the correct value to this field manually
+        #[deprecated(
+            since = "0.7.0",
+            note = "Use specialized PusTcCreator or PusTcReader classes instead"
+        )]
+        pub fn new(
+            sp_header: &mut SpHeader,
+            sec_header: PusTcSecondaryHeader,
+            app_data: Option<&'raw_data [u8]>,
+            set_ccsds_len: bool,
+        ) -> Self {
+            sp_header.set_packet_type(PacketType::Tc);
+            sp_header.set_sec_header_flag();
+            let mut pus_tc = Self {
+                sp_header: *sp_header,
+                raw_data: None,
+                app_data: app_data.unwrap_or(&[]),
+                sec_header,
+                calc_crc_on_serialization: true,
+                crc16: None,
+            };
+            if set_ccsds_len {
+                pus_tc.update_ccsds_data_len();
+            }
+            pus_tc
+        }
+
+        /// Simplified version of the [PusTc::new] function which allows to only specify service and
+        /// subservice instead of the full PUS TC secondary header.
+        #[deprecated(
+            since = "0.7.0",
+            note = "Use specialized PusTcCreator or PusTcReader classes instead"
+        )]
+        pub fn new_simple(
+            sph: &mut SpHeader,
+            service: u8,
+            subservice: u8,
+            app_data: Option<&'raw_data [u8]>,
+            set_ccsds_len: bool,
+        ) -> Self {
+            #[allow(deprecated)]
+            Self::new(
+                sph,
+                PusTcSecondaryHeader::new(service, subservice, ACK_ALL, 0),
+                app_data,
+                set_ccsds_len,
+            )
+        }
+
+        pub fn sp_header(&self) -> &SpHeader {
+            &self.sp_header
+        }
+
+        pub fn set_ack_field(&mut self, ack: u8) -> bool {
+            if ack > 0b1111 {
+                return false;
+            }
+            self.sec_header.ack = ack & 0b1111;
+            true
+        }
+
+        pub fn set_source_id(&mut self, source_id: u16) {
+            self.sec_header.source_id = source_id;
+        }
+
+        sp_header_impls!();
+
+        /// Calculate the CCSDS space packet data length field and sets it
+        /// This is called automatically if the `set_ccsds_len` argument in the [PusTc::new] call was
+        /// used.
+        /// If this was not done or the application data is set or changed after construction,
+        /// this function needs to be called to ensure that the data length field of the CCSDS header
+        /// is set correctly.
+        pub fn update_ccsds_data_len(&mut self) {
+            self.sp_header.data_len =
+                self.len_packed() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
+        }
+
+        /// This function should be called before the TC packet is serialized if
+        /// [PusTc::calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
+        pub fn calc_own_crc16(&mut self) {
+            let mut digest = CRC_CCITT_FALSE.digest();
+            let sph_zc = crate::zc::SpHeader::from(self.sp_header);
+            digest.update(sph_zc.as_bytes());
+            let pus_tc_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
+            digest.update(pus_tc_header.as_bytes());
+            if !self.app_data.is_empty() {
+                digest.update(self.app_data);
+            }
+            self.crc16 = Some(digest.finalize())
+        }
+
+        /// This helper function calls both [PusTc::update_ccsds_data_len] and [PusTc::calc_own_crc16].
+        pub fn update_packet_fields(&mut self) {
+            self.update_ccsds_data_len();
+            self.calc_own_crc16();
+        }
+
+        #[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 appended_len = PUS_TC_MIN_LEN_WITHOUT_APP_DATA + self.app_data.len();
+            let start_idx = vec.len();
+            let mut ser_len = 0;
+            vec.extend_from_slice(sph_zc.as_bytes());
+            ser_len += sph_zc.as_bytes().len();
+            // The PUS version is hardcoded to PUS C
+            let pus_tc_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
+            vec.extend_from_slice(pus_tc_header.as_bytes());
+            ser_len += pus_tc_header.as_bytes().len();
+            vec.extend_from_slice(self.app_data);
+            ser_len += self.app_data.len();
+            let crc16 = crc_procedure(
+                self.calc_crc_on_serialization,
+                &self.crc16,
+                start_idx,
+                ser_len,
+                &vec[start_idx..ser_len],
+            )?;
+            vec.extend_from_slice(crc16.to_be_bytes().as_slice());
+            Ok(appended_len)
+        }
+
+        /// Create a [PusTc] instance from a raw slice. On success, it returns a tuple containing
+        /// the instance and the found byte length of the packet.
+        #[deprecated(
+            since = "0.7.0",
+            note = "Use specialized PusTcCreator or PusTcReader classes instead"
+        )]
+        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));
+            }
+            let mut current_idx = 0;
+            let (sp_header, _) = SpHeader::from_be_bytes(&slice[0..CCSDS_HEADER_LEN])?;
+            current_idx += CCSDS_HEADER_LEN;
+            let total_len = sp_header.total_len();
+            if raw_data_len < total_len || total_len < PUS_TC_MIN_LEN_WITHOUT_APP_DATA {
+                return Err(PusError::RawDataTooShort(raw_data_len));
+            }
+            let sec_header = zc::PusTcSecondaryHeader::from_bytes(
+                &slice[current_idx..current_idx + PUC_TC_SECONDARY_HEADER_LEN],
+            )
+            .ok_or(ByteConversionError::ZeroCopyFromError)?;
+            current_idx += PUC_TC_SECONDARY_HEADER_LEN;
+            let raw_data = &slice[0..total_len];
+            let pus_tc = Self {
+                sp_header,
+                sec_header: PusTcSecondaryHeader::try_from(sec_header).unwrap(),
+                raw_data: Some(raw_data),
+                app_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
+                calc_crc_on_serialization: false,
+                crc16: Some(crc_from_raw_data(raw_data)?),
+            };
+            verify_crc16_ccitt_false_from_raw_to_pus_error(
+                raw_data,
+                pus_tc.crc16.expect("CRC16 invalid"),
+            )?;
+            Ok((pus_tc, total_len))
+        }
+
+        #[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 {
+            PUS_TC_MIN_LEN_WITHOUT_APP_DATA + self.app_data.len()
+        }
+
+        /// 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 {
+                    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;
+            slice[curr_idx..curr_idx + self.app_data.len()].copy_from_slice(self.app_data);
+            curr_idx += self.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
+        }
+    }
+
+    impl CcsdsPacket for PusTc<'_> {
+        ccsds_impl!();
+    }
+
+    impl PusPacket for PusTc<'_> {
+        delegate!(to self.sec_header {
+            fn pus_version(&self) -> PusVersion;
+            fn service(&self) -> u8;
+            fn subservice(&self) -> u8;
+        });
+
+        fn user_data(&self) -> &[u8] {
+            self.app_data
+        }
+
+        fn crc16(&self) -> Option<u16> {
+            self.crc16
+        }
+    }
+
+    impl GenericPusTcSecondaryHeader for PusTc<'_> {
+        delegate!(to self.sec_header {
+            fn pus_version(&self) -> PusVersion;
+            fn service(&self) -> u8;
+            fn subservice(&self) -> u8;
+            fn source_id(&self) -> u16;
+            fn ack_flags(&self) -> u8;
+        });
+    }
+
+    impl IsPusTelecommand for PusTc<'_> {}
+}
+
+/// This class can be used to create PUS C telecommand packet. It is the primary data structure to
+/// generate the raw byte representation of a PUS telecommand.
 ///
 /// 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.
-///
-/// # 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)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct PusTc<'raw_data> {
+pub struct PusTcCreator<'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<&'raw_data [u8]>,
-    app_data: Option<&'raw_data [u8]>,
-    crc16: Option<u16>,
+    app_data: &'raw_data [u8],
 }
 
-impl<'raw_data> PusTc<'raw_data> {
+impl<'raw_data> PusTcCreator<'raw_data> {
     /// Generates a new struct instance.
     ///
     /// # Arguments
@@ -255,13 +565,10 @@ impl<'raw_data> PusTc<'raw_data> {
     ) -> Self {
         sp_header.set_packet_type(PacketType::Tc);
         sp_header.set_sec_header_flag();
-        let mut pus_tc = PusTc {
+        let mut pus_tc = Self {
             sp_header: *sp_header,
-            raw_data: None,
-            app_data,
+            app_data: app_data.unwrap_or(&[]),
             sec_header,
-            calc_crc_on_serialization: true,
-            crc16: None,
         };
         if set_ccsds_len {
             pus_tc.update_ccsds_data_len();
@@ -269,8 +576,8 @@ impl<'raw_data> PusTc<'raw_data> {
         pus_tc
     }
 
-    /// Simplified version of the [PusTc::new] function which allows to only specify service and
-    /// subservice instead of the full PUS TC secondary header.
+    /// Simplified version of the [PusTcCreator::new] function which allows to only specify service
+    /// and subservice instead of the full PUS TC secondary header.
     pub fn new_simple(
         sph: &mut SpHeader,
         service: u8,
@@ -317,22 +624,14 @@ impl<'raw_data> PusTc<'raw_data> {
 
     /// This function should be called before the TC packet is serialized if
     /// [PusTc::calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
-    pub fn calc_own_crc16(&mut self) {
+    pub fn calc_own_crc16(&self) -> u16 {
         let mut digest = CRC_CCITT_FALSE.digest();
         let sph_zc = crate::zc::SpHeader::from(self.sp_header);
         digest.update(sph_zc.as_bytes());
         let pus_tc_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
         digest.update(pus_tc_header.as_bytes());
-        if let Some(app_data) = self.app_data {
-            digest.update(app_data);
-        }
-        self.crc16 = Some(digest.finalize())
-    }
-
-    /// This helper function calls both [PusTc::update_ccsds_data_len] and [PusTc::calc_own_crc16].
-    pub fn update_packet_fields(&mut self) {
-        self.update_ccsds_data_len();
-        self.calc_own_crc16();
+        digest.update(self.app_data);
+        digest.finalize()
     }
 
     #[cfg(feature = "alloc")]
@@ -340,35 +639,113 @@ impl<'raw_data> PusTc<'raw_data> {
     pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> Result<usize, PusError> {
         let sph_zc = crate::zc::SpHeader::from(self.sp_header);
         let mut appended_len = PUS_TC_MIN_LEN_WITHOUT_APP_DATA;
-        if let Some(app_data) = self.app_data {
-            appended_len += app_data.len();
-        };
+        appended_len += self.app_data.len();
         let start_idx = vec.len();
-        let mut ser_len = 0;
         vec.extend_from_slice(sph_zc.as_bytes());
-        ser_len += sph_zc.as_bytes().len();
         // The PUS version is hardcoded to PUS C
         let pus_tc_header = zc::PusTcSecondaryHeader::try_from(self.sec_header).unwrap();
         vec.extend_from_slice(pus_tc_header.as_bytes());
-        ser_len += pus_tc_header.as_bytes().len();
-        if let Some(app_data) = self.app_data {
-            vec.extend_from_slice(app_data);
-            ser_len += app_data.len();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            start_idx,
-            ser_len,
-            &vec[start_idx..ser_len],
-        )?;
-        vec.extend_from_slice(crc16.to_be_bytes().as_slice());
+        vec.extend_from_slice(self.app_data);
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&vec[start_idx..start_idx + appended_len - 2]);
+        vec.extend_from_slice(&digest.finalize().to_be_bytes());
         Ok(appended_len)
     }
+}
 
-    /// Create a [PusTc] instance from a raw slice. On success, it returns a tuple containing
+impl SerializablePusPacket for PusTcCreator<'_> {
+    fn len_packed(&self) -> usize {
+        PUS_TC_MIN_LEN_WITHOUT_APP_DATA + self.app_data.len()
+    }
+
+    /// 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 {
+                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;
+        slice[curr_idx..curr_idx + self.app_data.len()].copy_from_slice(self.app_data);
+        curr_idx += self.app_data.len();
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&slice[0..curr_idx]);
+        slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+        curr_idx += 2;
+        Ok(curr_idx)
+    }
+}
+
+impl CcsdsPacket for PusTcCreator<'_> {
+    ccsds_impl!();
+}
+
+impl PusPacket for PusTcCreator<'_> {
+    delegate!(to self.sec_header {
+        fn pus_version(&self) -> PusVersion;
+        fn service(&self) -> u8;
+        fn subservice(&self) -> u8;
+    });
+
+    fn user_data(&self) -> &[u8] {
+        self.app_data
+    }
+
+    fn crc16(&self) -> Option<u16> {
+        Some(self.calc_own_crc16())
+    }
+}
+
+impl GenericPusTcSecondaryHeader for PusTcCreator<'_> {
+    delegate!(to self.sec_header {
+        fn pus_version(&self) -> PusVersion;
+        fn service(&self) -> u8;
+        fn subservice(&self) -> u8;
+        fn source_id(&self) -> u16;
+        fn ack_flags(&self) -> u8;
+    });
+}
+
+impl IsPusTelecommand for PusTcCreator<'_> {}
+
+/// This class can be used to read a PUS TC telecommand from raw memory.
+///
+/// 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.
+///
+/// # Lifetimes
+///
+/// * `'raw_data` - Lifetime of the provided raw slice.
+#[derive(Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct PusTcReader<'raw_data> {
+    #[cfg_attr(feature = "serde", serde(skip))]
+    raw_data: &'raw_data [u8],
+    sp_header: SpHeader,
+    sec_header: PusTcSecondaryHeader,
+    app_data: &'raw_data [u8],
+    crc16: u16,
+}
+
+impl<'raw_data> PusTcReader<'raw_data> {
+    /// Create a [PusTcReader] 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: &'raw_data [u8]) -> Result<(Self, usize), PusError> {
+    pub fn new(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));
@@ -386,111 +763,61 @@ impl<'raw_data> PusTc<'raw_data> {
         .ok_or(ByteConversionError::ZeroCopyFromError)?;
         current_idx += PUC_TC_SECONDARY_HEADER_LEN;
         let raw_data = &slice[0..total_len];
-        let pus_tc = PusTc {
+        let pus_tc = Self {
             sp_header,
             sec_header: PusTcSecondaryHeader::try_from(sec_header).unwrap(),
-            raw_data: Some(raw_data),
-            app_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
-            calc_crc_on_serialization: false,
-            crc16: Some(crc_from_raw_data(raw_data)?),
-        };
-        verify_crc16_ccitt_false_from_raw_to_pus_error(
             raw_data,
-            pus_tc.crc16.expect("CRC16 invalid"),
-        )?;
+            app_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
+            crc16: crc_from_raw_data(raw_data)?,
+        };
+        verify_crc16_ccitt_false_from_raw_to_pus_error(raw_data, pus_tc.crc16)?;
         Ok((pus_tc, total_len))
     }
 
-    #[deprecated(since = "0.5.2", note = "use raw_bytes() instead")]
-    pub fn raw(&self) -> Option<&'raw_data [u8]> {
-        self.raw_bytes()
+    pub fn app_data(&self) -> &[u8] {
+        self.user_data()
     }
 
-    /// 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]> {
+    pub fn raw_data(&self) -> &[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
+    pub fn len_packed(&self) -> usize {
+        self.sp_header.total_len()
     }
 
-    /// 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)
+    pub fn sp_header(&self) -> &SpHeader {
+        &self.sp_header
     }
 }
 
-impl PartialEq for PusTc<'_> {
+impl PartialEq for PusTcReader<'_> {
     fn eq(&self, other: &Self) -> bool {
-        self.sp_header == other.sp_header
-            && self.sec_header == other.sec_header
-            && self.app_data == other.app_data
+        self.raw_data == other.raw_data
     }
 }
 
-//noinspection RsTraitImplementation
-impl CcsdsPacket for PusTc<'_> {
+impl CcsdsPacket for PusTcReader<'_> {
     ccsds_impl!();
 }
 
-//noinspection RsTraitImplementation
-impl PusPacket for PusTc<'_> {
+impl PusPacket for PusTcReader<'_> {
     delegate!(to self.sec_header {
         fn pus_version(&self) -> PusVersion;
         fn service(&self) -> u8;
         fn subservice(&self) -> u8;
     });
 
-    fn user_data(&self) -> Option<&[u8]> {
+    fn user_data(&self) -> &[u8] {
         self.app_data
     }
 
     fn crc16(&self) -> Option<u16> {
-        self.crc16
+        Some(self.crc16)
     }
 }
 
-//noinspection RsTraitImplementation
-impl GenericPusTcSecondaryHeader for PusTc<'_> {
+impl GenericPusTcSecondaryHeader for PusTcReader<'_> {
     delegate!(to self.sec_header {
         fn pus_version(&self) -> PusVersion;
         fn service(&self) -> u8;
@@ -500,36 +827,54 @@ impl GenericPusTcSecondaryHeader for PusTc<'_> {
     });
 }
 
+impl IsPusTelecommand for PusTcReader<'_> {}
+
+impl PartialEq<PusTcCreator<'_>> for PusTcReader<'_> {
+    fn eq(&self, other: &PusTcCreator) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.app_data == other.app_data
+    }
+}
+
+impl PartialEq<PusTcReader<'_>> for PusTcCreator<'_> {
+    fn eq(&self, other: &PusTcReader) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.app_data == other.app_data
+    }
+}
+
 #[cfg(all(test, feature = "std"))]
 mod tests {
+    use crate::ecss::tc::{
+        GenericPusTcSecondaryHeader, PusTcCreator, PusTcReader, PusTcSecondaryHeader, ACK_ALL,
+    };
     use crate::ecss::PusVersion::PusC;
     use crate::ecss::{PusError, PusPacket, SerializablePusPacket};
-    use crate::tc::ACK_ALL;
-    use crate::tc::{GenericPusTcSecondaryHeader, PusTc, PusTcSecondaryHeader};
     use crate::{ByteConversionError, SpHeader};
     use crate::{CcsdsPacket, SequenceFlags};
     use alloc::vec::Vec;
 
-    fn base_ping_tc_full_ctor() -> PusTc<'static> {
+    fn base_ping_tc_full_ctor() -> PusTcCreator<'static> {
         let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
         let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
-        PusTc::new(&mut sph, tc_header, None, true)
+        PusTcCreator::new(&mut sph, tc_header, None, true)
     }
 
-    fn base_ping_tc_simple_ctor() -> PusTc<'static> {
+    fn base_ping_tc_simple_ctor() -> PusTcCreator<'static> {
         let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
-        PusTc::new_simple(&mut sph, 17, 1, None, true)
+        PusTcCreator::new_simple(&mut sph, 17, 1, None, true)
     }
 
-    fn base_ping_tc_simple_ctor_with_app_data(app_data: &'static [u8]) -> PusTc<'static> {
+    fn base_ping_tc_simple_ctor_with_app_data(app_data: &'static [u8]) -> PusTcCreator<'static> {
         let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
-        PusTc::new_simple(&mut sph, 17, 1, Some(app_data), true)
+        PusTcCreator::new_simple(&mut sph, 17, 1, Some(app_data), true)
     }
 
     #[test]
     fn test_tc_fields() {
         let pus_tc = base_ping_tc_full_ctor();
-        assert_eq!(pus_tc.crc16(), None);
         verify_test_tc(&pus_tc, false, 13);
     }
 
@@ -552,10 +897,10 @@ mod tests {
             .expect("Error writing TC to buffer");
         assert_eq!(size, 13);
         let (tc_from_raw, size) =
-            PusTc::from_bytes(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
+            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
         assert_eq!(size, 13);
-        verify_test_tc(&tc_from_raw, false, 13);
-        assert!(tc_from_raw.user_data().is_none());
+        verify_test_tc_with_reader(&tc_from_raw, false, 13);
+        assert!(tc_from_raw.user_data().is_empty());
         verify_test_tc_raw(&test_buf);
         verify_crc_no_app_data(&test_buf);
     }
@@ -563,10 +908,9 @@ mod tests {
     #[test]
     fn test_update_func() {
         let mut sph = SpHeader::tc_unseg(0x02, 0x34, 0).unwrap();
-        let mut tc = PusTc::new_simple(&mut sph, 17, 1, None, false);
-        tc.calc_crc_on_serialization = false;
+        let mut tc = PusTcCreator::new_simple(&mut sph, 17, 1, None, false);
         assert_eq!(tc.data_len(), 0);
-        tc.update_packet_fields();
+        tc.update_ccsds_data_len();
         assert_eq!(tc.data_len(), 6);
     }
     #[test]
@@ -578,10 +922,10 @@ mod tests {
             .expect("Error writing TC to buffer");
         assert_eq!(size, 16);
         let (tc_from_raw, size) =
-            PusTc::from_bytes(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
+            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
         assert_eq!(size, 16);
-        verify_test_tc(&tc_from_raw, true, 16);
-        let user_data = tc_from_raw.user_data().unwrap();
+        verify_test_tc_with_reader(&tc_from_raw, true, 16);
+        let user_data = tc_from_raw.user_data();
         assert_eq!(user_data[0], 1);
         assert_eq!(user_data[1], 2);
         assert_eq!(user_data[2], 3);
@@ -607,7 +951,7 @@ mod tests {
             .write_to_bytes(test_buf.as_mut_slice())
             .expect("Error writing TC to buffer");
         test_buf[12] = 0;
-        let res = PusTc::from_bytes(&test_buf);
+        let res = PusTcReader::new(&test_buf);
         assert!(res.is_err());
         let err = res.unwrap_err();
         assert!(matches!(err, PusError::IncorrectCrc { .. }));
@@ -615,8 +959,7 @@ mod tests {
 
     #[test]
     fn test_manual_crc_calculation() {
-        let mut pus_tc = base_ping_tc_simple_ctor();
-        pus_tc.calc_crc_on_serialization = false;
+        let pus_tc = base_ping_tc_simple_ctor();
         let mut test_buf: [u8; 32] = [0; 32];
         pus_tc.calc_own_crc16();
         pus_tc
@@ -626,17 +969,6 @@ mod tests {
         verify_crc_no_app_data(&test_buf);
     }
 
-    #[test]
-    fn test_manual_crc_calculation_no_calc_call() {
-        let mut pus_tc = base_ping_tc_simple_ctor();
-        pus_tc.calc_crc_on_serialization = false;
-        let mut test_buf: [u8; 32] = [0; 32];
-        let res = pus_tc.write_to_bytes(test_buf.as_mut_slice());
-        assert!(res.is_err());
-        let err = res.unwrap_err();
-        assert!(matches!(err, PusError::CrcCalculationMissing { .. }));
-    }
-
     #[test]
     fn test_with_application_data_vec() {
         let pus_tc = base_ping_tc_simple_ctor_with_app_data(&[1, 2, 3]);
@@ -659,10 +991,10 @@ mod tests {
         assert!(res.is_err());
         let err = res.unwrap_err();
         match err {
-            PusError::ByteConversionError(err) => match err {
-                ByteConversionError::ToSliceTooSmall(missmatch) => {
-                    assert_eq!(missmatch.expected, pus_tc.len_packed());
-                    assert_eq!(missmatch.found, 12);
+            PusError::ByteConversion(err) => match err {
+                ByteConversionError::ToSliceTooSmall { found, expected } => {
+                    assert_eq!(expected, pus_tc.len_packed());
+                    assert_eq!(found, 12);
                 }
                 _ => panic!("Unexpected error"),
             },
@@ -712,24 +1044,37 @@ mod tests {
         assert_eq!(test_buf[10], 0xff);
     }
 
-    fn verify_test_tc(tc: &PusTc, has_user_data: bool, exp_full_len: usize) {
+    fn verify_test_tc(tc: &PusTcCreator, has_user_data: bool, exp_full_len: usize) {
+        verify_test_tc_generic(tc);
+        if !has_user_data {
+            assert!(tc.user_data().is_empty());
+        }
+        let mut comp_header = SpHeader::tc_unseg(0x02, 0x34, exp_full_len as u16 - 7).unwrap();
+        comp_header.set_sec_header_flag();
+        assert_eq!(*tc.sp_header(), comp_header);
+    }
+
+    fn verify_test_tc_with_reader(tc: &PusTcReader, has_user_data: bool, exp_full_len: usize) {
+        verify_test_tc_generic(tc);
+        if !has_user_data {
+            assert!(tc.user_data().is_empty());
+        }
+        assert_eq!(tc.len_packed(), exp_full_len);
+        let mut comp_header = SpHeader::tc_unseg(0x02, 0x34, exp_full_len as u16 - 7).unwrap();
+        comp_header.set_sec_header_flag();
+        assert_eq!(*tc.sp_header(), comp_header);
+    }
+
+    fn verify_test_tc_generic(tc: &(impl CcsdsPacket + PusPacket + GenericPusTcSecondaryHeader)) {
         assert_eq!(PusPacket::service(tc), 17);
         assert_eq!(PusPacket::subservice(tc), 1);
         assert!(tc.sec_header_flag());
         assert_eq!(PusPacket::pus_version(tc), PusC);
-        if !has_user_data {
-            assert_eq!(tc.user_data(), None);
-        }
         assert_eq!(tc.seq_count(), 0x34);
         assert_eq!(tc.source_id(), 0);
         assert_eq!(tc.apid(), 0x02);
         assert_eq!(tc.ack_flags(), ACK_ALL);
-        assert_eq!(tc.len_packed(), exp_full_len);
-        let mut comp_header = SpHeader::tc_unseg(0x02, 0x34, exp_full_len as u16 - 7).unwrap();
-        comp_header.set_sec_header_flag();
-        assert_eq!(tc.sp_header, comp_header);
     }
-
     fn verify_test_tc_raw(slice: &impl AsRef<[u8]>) {
         // Reference comparison implementation:
         // https://github.com/us-irs/py-spacepackets/blob/v0.13.0/tests/ecss/test_pus_tc.py
@@ -777,6 +1122,7 @@ mod tests {
         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);
+        assert_eq!(pus_tc, PusTcReader::new(&buf).unwrap().0);
+        assert_eq!(PusTcReader::new(&buf).unwrap().0, pus_tc);
     }
 }

src/ecss/tm.rs

@@ -1,13 +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::{
-    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,
+    calc_pus_crc16, ccsds_impl, crc_from_raw_data, 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, CRC_CCITT_FALSE, MAX_APID, MAX_SEQ_COUNT,
+    ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SpHeader, CCSDS_HEADER_LEN,
+    CRC_CCITT_FALSE, MAX_APID, MAX_SEQ_COUNT,
 };
 use core::mem::size_of;
 #[cfg(feature = "serde")]
@@ -18,6 +18,11 @@ use zerocopy::AsBytes;
 use alloc::vec::Vec;
 use delegate::delegate;
 
+use crate::time::{TimeWriter, TimestampError};
+pub use legacy_tm::*;
+
+pub trait IsPusTelemetry {}
+
 /// Length without timestamp
 pub const PUC_TM_MIN_SEC_HEADER_LEN: usize = 7;
 pub const PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA: usize =
@@ -35,9 +40,9 @@ pub trait GenericPusTmSecondaryHeader {
 pub mod zc {
     use super::GenericPusTmSecondaryHeader;
     use crate::ecss::{PusError, PusVersion};
-    use zerocopy::{AsBytes, FromBytes, NetworkEndian, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, NetworkEndian, Unaligned, U16};
 
-    #[derive(FromBytes, AsBytes, Unaligned)]
+    #[derive(FromBytes, FromZeroes, AsBytes, Unaligned)]
     #[repr(C)]
     pub struct PusTmSecHeaderWithoutTimestamp {
         pus_version_and_sc_time_ref_status: u8,
@@ -49,12 +54,12 @@ pub mod zc {
 
     pub struct PusTmSecHeader<'slice> {
         pub(crate) zc_header: PusTmSecHeaderWithoutTimestamp,
-        pub(crate) timestamp: Option<&'slice [u8]>,
+        pub(crate) timestamp: &'slice [u8],
     }
 
-    impl TryFrom<crate::tm::PusTmSecondaryHeader<'_>> for PusTmSecHeaderWithoutTimestamp {
+    impl TryFrom<crate::ecss::tm::PusTmSecondaryHeader<'_>> for PusTmSecHeaderWithoutTimestamp {
         type Error = PusError;
-        fn try_from(header: crate::tm::PusTmSecondaryHeader) -> Result<Self, Self::Error> {
+        fn try_from(header: crate::ecss::tm::PusTmSecondaryHeader) -> Result<Self, Self::Error> {
             if header.pus_version != PusVersion::PusC {
                 return Err(PusError::VersionNotSupported(header.pus_version));
             }
@@ -116,7 +121,7 @@ pub struct PusTmSecondaryHeader<'stamp> {
     pub subservice: u8,
     pub msg_counter: u16,
     pub dest_id: u16,
-    pub timestamp: Option<&'stamp [u8]>,
+    pub timestamp: &'stamp [u8],
 }
 
 impl<'stamp> PusTmSecondaryHeader<'stamp> {
@@ -143,7 +148,7 @@ impl<'stamp> PusTmSecondaryHeader<'stamp> {
             subservice,
             msg_counter,
             dest_id,
-            timestamp,
+            timestamp: timestamp.unwrap_or(&[]),
         }
     }
 }
@@ -190,8 +195,322 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
     }
 }
 
+pub mod legacy_tm {
+    use crate::ecss::tm::{
+        zc, GenericPusTmSecondaryHeader, IsPusTelemetry, PusTmSecondaryHeader,
+        PUC_TM_MIN_SEC_HEADER_LEN, PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA,
+    };
+    use crate::ecss::PusVersion;
+    use crate::ecss::{
+        ccsds_impl, crc_from_raw_data, crc_procedure, sp_header_impls, user_data_from_raw,
+        verify_crc16_ccitt_false_from_raw_to_pus_error, PusError, PusPacket, SerializablePusPacket,
+        CCSDS_HEADER_LEN,
+    };
+    use crate::SequenceFlags;
+    use crate::{ByteConversionError, CcsdsPacket, PacketType, SpHeader, CRC_CCITT_FALSE};
+    use core::mem::size_of;
+    use zerocopy::AsBytes;
+
+    #[cfg(feature = "serde")]
+    use serde::{Deserialize, Serialize};
+
+    #[cfg(feature = "alloc")]
+    use alloc::vec::Vec;
+    use delegate::delegate;
+
+    /// 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
+    /// provider like [postcard](https://docs.rs/postcard/latest/postcard/).
+    ///
+    /// There is no spare bytes support yet.
+    ///
+    /// # Lifetimes
+    ///
+    /// * `'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<'raw_data> {
+        pub sp_header: SpHeader,
+        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<&'raw_data [u8]>,
+        source_data: &'raw_data [u8],
+        crc16: Option<u16>,
+    }
+
+    impl<'raw_data> PusTm<'raw_data> {
+        /// Generates a new struct instance.
+        ///
+        /// # Arguments
+        ///
+        /// * `sp_header` - Space packet header information. The correct packet type will be set
+        ///     automatically
+        /// * `sec_header` - Information contained in the secondary header, including the service
+        ///     and subservice type
+        /// * `app_data` - Custom application data
+        /// * `set_ccsds_len` - Can be used to automatically update the CCSDS space packet data length
+        ///     field. If this is not set to true, [PusTm::update_ccsds_data_len] can be called to set
+        ///     the correct value to this field manually
+        #[deprecated(
+            since = "0.7.0",
+            note = "Use specialized PusTmCreator or PusTmReader classes instead"
+        )]
+        pub fn new(
+            sp_header: &mut SpHeader,
+            sec_header: PusTmSecondaryHeader<'raw_data>,
+            source_data: Option<&'raw_data [u8]>,
+            set_ccsds_len: bool,
+        ) -> Self {
+            sp_header.set_packet_type(PacketType::Tm);
+            sp_header.set_sec_header_flag();
+            let mut pus_tm = PusTm {
+                sp_header: *sp_header,
+                raw_data: None,
+                source_data: source_data.unwrap_or(&[]),
+                sec_header,
+                calc_crc_on_serialization: true,
+                crc16: None,
+            };
+            if set_ccsds_len {
+                pus_tm.update_ccsds_data_len();
+            }
+            pus_tm
+        }
+
+        pub fn timestamp(&self) -> &[u8] {
+            self.sec_header.timestamp
+        }
+
+        pub fn source_data(&self) -> &[u8] {
+            self.source_data
+        }
+
+        pub fn set_dest_id(&mut self, dest_id: u16) {
+            self.sec_header.dest_id = dest_id;
+        }
+
+        pub fn set_msg_counter(&mut self, msg_counter: u16) {
+            self.sec_header.msg_counter = msg_counter
+        }
+
+        pub fn set_sc_time_ref_status(&mut self, sc_time_ref_status: u8) {
+            self.sec_header.sc_time_ref_status = sc_time_ref_status & 0b1111;
+        }
+
+        sp_header_impls!();
+
+        /// This is called automatically if the `set_ccsds_len` argument in the [PusTm::new] call was
+        /// used.
+        /// If this was not done or the time stamp or source data is set or changed after construction,
+        /// this function needs to be called to ensure that the data length field of the CCSDS header
+        /// is set correctly
+        pub fn update_ccsds_data_len(&mut self) {
+            self.sp_header.data_len =
+                self.len_packed() as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
+        }
+
+        /// This function should be called before the TM packet is serialized if
+        /// [PusTm.calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
+        pub fn calc_own_crc16(&mut self) {
+            let mut digest = CRC_CCITT_FALSE.digest();
+            let sph_zc = crate::zc::SpHeader::from(self.sp_header);
+            digest.update(sph_zc.as_bytes());
+            let pus_tc_header =
+                zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
+            digest.update(pus_tc_header.as_bytes());
+            digest.update(self.sec_header.timestamp);
+            digest.update(self.source_data);
+            self.crc16 = Some(digest.finalize())
+        }
+
+        /// This helper function calls both [PusTm.update_ccsds_data_len] and [PusTm.calc_own_crc16]
+        pub fn update_packet_fields(&mut self) {
+            self.update_ccsds_data_len();
+            self.calc_own_crc16();
+        }
+
+        /// 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;
+            appended_len += self.sec_header.timestamp.len();
+            appended_len += self.source_data.len();
+            let start_idx = vec.len();
+            let mut ser_len = 0;
+            vec.extend_from_slice(sph_zc.as_bytes());
+            ser_len += sph_zc.as_bytes().len();
+            // The PUS version is hardcoded to PUS C
+            let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
+            vec.extend_from_slice(sec_header.as_bytes());
+            ser_len += sec_header.as_bytes().len();
+            ser_len += self.sec_header.timestamp.len();
+            vec.extend_from_slice(self.sec_header.timestamp);
+            vec.extend_from_slice(self.source_data);
+            ser_len += self.source_data.len();
+            let crc16 = crc_procedure(
+                self.calc_crc_on_serialization,
+                &self.crc16,
+                start_idx,
+                ser_len,
+                &vec[start_idx..start_idx + ser_len],
+            )?;
+            vec.extend_from_slice(crc16.to_be_bytes().as_slice());
+            Ok(appended_len)
+        }
+
+        /// Create a [PusTm] instance from a raw slice. On success, it returns a tuple containing
+        /// the instance and the found byte length of the packet. The timestamp length needs to be
+        /// known beforehand.
+        #[deprecated(
+            since = "0.7.0",
+            note = "Use specialized PusTmCreator or PusTmReader classes instead"
+        )]
+        pub fn from_bytes(
+            slice: &'raw_data [u8],
+            timestamp_len: usize,
+        ) -> Result<(Self, usize), PusError> {
+            let raw_data_len = slice.len();
+            if raw_data_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
+                return Err(PusError::RawDataTooShort(raw_data_len));
+            }
+            let mut current_idx = 0;
+            let (sp_header, _) = SpHeader::from_be_bytes(&slice[0..CCSDS_HEADER_LEN])?;
+            current_idx += 6;
+            let total_len = sp_header.total_len();
+            if raw_data_len < total_len || total_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
+                return Err(PusError::RawDataTooShort(raw_data_len));
+            }
+            let sec_header_zc = zc::PusTmSecHeaderWithoutTimestamp::from_bytes(
+                &slice[current_idx..current_idx + PUC_TM_MIN_SEC_HEADER_LEN],
+            )
+            .ok_or(ByteConversionError::ZeroCopyFromError)?;
+            current_idx += PUC_TM_MIN_SEC_HEADER_LEN;
+            let zc_sec_header_wrapper = zc::PusTmSecHeader {
+                zc_header: sec_header_zc,
+                timestamp: &slice[current_idx..current_idx + timestamp_len],
+            };
+            current_idx += timestamp_len;
+            let raw_data = &slice[0..total_len];
+            let pus_tm = PusTm {
+                sp_header,
+                sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper).unwrap(),
+                raw_data: Some(&slice[0..total_len]),
+                source_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
+                calc_crc_on_serialization: false,
+                crc16: Some(crc_from_raw_data(raw_data)?),
+            };
+            verify_crc16_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
+        }
+    }
+
+    impl SerializablePusPacket for PusTm<'_> {
+        fn len_packed(&self) -> usize {
+            PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA
+                + self.sec_header.timestamp.len()
+                + self.source_data.len()
+        }
+        /// 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 {
+                    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;
+            slice[curr_idx..curr_idx + self.sec_header.timestamp.len()]
+                .copy_from_slice(self.sec_header.timestamp);
+            curr_idx += self.sec_header.timestamp.len();
+            slice[curr_idx..curr_idx + self.source_data.len()].copy_from_slice(self.source_data);
+            curr_idx += self.source_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
+        }
+    }
+
+    impl CcsdsPacket for PusTm<'_> {
+        ccsds_impl!();
+    }
+
+    impl PusPacket for PusTm<'_> {
+        delegate!(to self.sec_header {
+            fn pus_version(&self) -> PusVersion;
+            fn service(&self) -> u8;
+            fn subservice(&self) -> u8;
+        });
+
+        fn user_data(&self) -> &[u8] {
+            self.source_data
+        }
+
+        fn crc16(&self) -> Option<u16> {
+            self.crc16
+        }
+    }
+
+    impl GenericPusTmSecondaryHeader for PusTm<'_> {
+        delegate!(to self.sec_header {
+            fn pus_version(&self) -> PusVersion;
+            fn service(&self) -> u8;
+            fn subservice(&self) -> u8;
+            fn dest_id(&self) -> u16;
+            fn msg_counter(&self) -> u16;
+            fn sc_time_ref_status(&self) -> u8;
+        });
+    }
+
+    impl IsPusTelemetry for PusTm<'_> {}
+}
+
 /// 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.
+/// raw byte representation of PUS telemetry.
 ///
 /// 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
@@ -201,24 +520,19 @@ impl<'slice> TryFrom<zc::PusTmSecHeader<'slice>> for PusTmSecondaryHeader<'slice
 ///
 /// # Lifetimes
 ///
-/// * `'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.
+/// * `'raw_data` - This is the lifetime of the user provided time stamp and source data.
 #[derive(Eq, Debug, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct PusTm<'raw_data> {
+pub struct PusTmCreator<'raw_data> {
     pub sp_header: SpHeader,
     pub sec_header: PusTmSecondaryHeader<'raw_data>,
+    source_data: &'raw_data [u8],
     /// 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<&'raw_data [u8]>,
-    source_data: Option<&'raw_data [u8]>,
-    crc16: Option<u16>,
 }
 
-impl<'raw_data> PusTm<'raw_data> {
+impl<'raw_data> PusTmCreator<'raw_data> {
     /// Generates a new struct instance.
     ///
     /// # Arguments
@@ -239,13 +553,11 @@ impl<'raw_data> PusTm<'raw_data> {
     ) -> Self {
         sp_header.set_packet_type(PacketType::Tm);
         sp_header.set_sec_header_flag();
-        let mut pus_tm = PusTm {
+        let mut pus_tm = Self {
             sp_header: *sp_header,
-            raw_data: None,
-            source_data,
+            source_data: source_data.unwrap_or(&[]),
             sec_header,
             calc_crc_on_serialization: true,
-            crc16: None,
         };
         if set_ccsds_len {
             pus_tm.update_ccsds_data_len();
@@ -253,11 +565,25 @@ impl<'raw_data> PusTm<'raw_data> {
         pus_tm
     }
 
-    pub fn timestamp(&self) -> Option<&'raw_data [u8]> {
+    pub fn new_simple(
+        sp_header: &mut SpHeader,
+        service: u8,
+        subservice: u8,
+        time_provider: &impl TimeWriter,
+        stamp_buf: &'raw_data mut [u8],
+        source_data: Option<&'raw_data [u8]>,
+        set_ccsds_len: bool,
+    ) -> Result<Self, TimestampError> {
+        let stamp_size = time_provider.write_to_bytes(stamp_buf)?;
+        let sec_header =
+            PusTmSecondaryHeader::new_simple(service, subservice, &stamp_buf[0..stamp_size]);
+        Ok(Self::new(sp_header, sec_header, source_data, set_ccsds_len))
+    }
+    pub fn timestamp(&self) -> &[u8] {
         self.sec_header.timestamp
     }
 
-    pub fn source_data(&self) -> Option<&'raw_data [u8]> {
+    pub fn source_data(&self) -> &[u8] {
         self.source_data
     }
 
@@ -287,25 +613,20 @@ impl<'raw_data> PusTm<'raw_data> {
 
     /// This function should be called before the TM packet is serialized if
     /// [PusTm.calc_crc_on_serialization] is set to False. It will calculate and cache the CRC16.
-    pub fn calc_own_crc16(&mut self) {
+    pub fn calc_own_crc16(&self) -> u16 {
         let mut digest = CRC_CCITT_FALSE.digest();
         let sph_zc = crate::zc::SpHeader::from(self.sp_header);
         digest.update(sph_zc.as_bytes());
         let pus_tc_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
         digest.update(pus_tc_header.as_bytes());
-        if let Some(stamp) = self.sec_header.timestamp {
-            digest.update(stamp);
-        }
-        if let Some(src_data) = self.source_data {
-            digest.update(src_data);
-        }
-        self.crc16 = Some(digest.finalize())
+        digest.update(self.sec_header.timestamp);
+        digest.update(self.source_data);
+        digest.finalize()
     }
 
     /// This helper function calls both [PusTm.update_ccsds_data_len] and [PusTm.calc_own_crc16]
     pub fn update_packet_fields(&mut self) {
         self.update_ccsds_data_len();
-        self.calc_own_crc16();
     }
 
     /// Append the raw PUS byte representation to a provided [alloc::vec::Vec]
@@ -313,47 +634,130 @@ impl<'raw_data> PusTm<'raw_data> {
     #[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;
-        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();
-        };
+        let mut appended_len = PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA + self.sec_header.timestamp.len();
+        appended_len += self.source_data.len();
         let start_idx = vec.len();
-        let mut ser_len = 0;
         vec.extend_from_slice(sph_zc.as_bytes());
-        ser_len += sph_zc.as_bytes().len();
         // The PUS version is hardcoded to PUS C
         let sec_header = zc::PusTmSecHeaderWithoutTimestamp::try_from(self.sec_header).unwrap();
         vec.extend_from_slice(sec_header.as_bytes());
-        ser_len += sec_header.as_bytes().len();
-        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();
-        }
-        let crc16 = crc_procedure(
-            self.calc_crc_on_serialization,
-            &self.crc16,
-            start_idx,
-            ser_len,
-            &vec[start_idx..start_idx + ser_len],
-        )?;
-        vec.extend_from_slice(crc16.to_be_bytes().as_slice());
+        vec.extend_from_slice(self.sec_header.timestamp);
+        vec.extend_from_slice(self.source_data);
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&vec[start_idx..start_idx + appended_len - 2]);
+        vec.extend_from_slice(&digest.finalize().to_be_bytes());
         Ok(appended_len)
     }
+}
 
-    /// Create a [PusTm] instance from a raw slice. On success, it returns a tuple containing
+impl SerializablePusPacket for PusTmCreator<'_> {
+    fn len_packed(&self) -> usize {
+        PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA
+            + self.sec_header.timestamp.len()
+            + self.source_data.len()
+    }
+    /// 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 {
+                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;
+        slice[curr_idx..curr_idx + self.sec_header.timestamp.len()]
+            .copy_from_slice(self.sec_header.timestamp);
+        curr_idx += self.sec_header.timestamp.len();
+        slice[curr_idx..curr_idx + self.source_data.len()].copy_from_slice(self.source_data);
+        curr_idx += self.source_data.len();
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&slice[0..curr_idx]);
+        slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
+        curr_idx += 2;
+        Ok(curr_idx)
+    }
+}
+
+impl PartialEq for PusTmCreator<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.source_data == other.source_data
+    }
+}
+
+impl CcsdsPacket for PusTmCreator<'_> {
+    ccsds_impl!();
+}
+
+impl PusPacket for PusTmCreator<'_> {
+    delegate!(to self.sec_header {
+        fn pus_version(&self) -> PusVersion;
+        fn service(&self) -> u8;
+        fn subservice(&self) -> u8;
+    });
+
+    fn user_data(&self) -> &[u8] {
+        self.source_data
+    }
+
+    fn crc16(&self) -> Option<u16> {
+        Some(self.calc_own_crc16())
+    }
+}
+
+impl GenericPusTmSecondaryHeader for PusTmCreator<'_> {
+    delegate!(to self.sec_header {
+        fn pus_version(&self) -> PusVersion;
+        fn service(&self) -> u8;
+        fn subservice(&self) -> u8;
+        fn dest_id(&self) -> u16;
+        fn msg_counter(&self) -> u16;
+        fn sc_time_ref_status(&self) -> u8;
+    });
+}
+
+impl IsPusTelemetry for PusTmCreator<'_> {}
+
+/// This class models the PUS C telemetry packet. It is the primary data structure to read
+/// a telemetry packet 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
+/// provider like [postcard](https://docs.rs/postcard/latest/postcard/).
+///
+/// There is no spare bytes support yet.
+///
+/// # Lifetimes
+///
+/// * `'raw_data` - Lifetime of the raw slice this class is constructed from.
+#[derive(Eq, Debug, Copy, Clone)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub struct PusTmReader<'raw_data> {
+    pub sp_header: SpHeader,
+    pub sec_header: PusTmSecondaryHeader<'raw_data>,
+    #[cfg_attr(feature = "serde", serde(skip))]
+    raw_data: &'raw_data [u8],
+    source_data: &'raw_data [u8],
+    crc16: u16,
+}
+
+impl<'raw_data> PusTmReader<'raw_data> {
+    /// Create a [PusTmReader] instance from a raw slice. On success, it returns a tuple containing
     /// the instance and the found byte length of the packet. The timestamp length needs to be
     /// known beforehand.
-    pub fn from_bytes(
-        slice: &'raw_data [u8],
-        timestamp_len: usize,
-    ) -> Result<(Self, usize), PusError> {
+    pub fn new(slice: &'raw_data [u8], timestamp_len: usize) -> Result<(Self, usize), PusError> {
         let raw_data_len = slice.len();
         if raw_data_len < PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA {
             return Err(PusError::RawDataTooShort(raw_data_len));
@@ -370,38 +774,96 @@ impl<'raw_data> PusTm<'raw_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,
+            timestamp: &slice[current_idx..current_idx + timestamp_len],
         };
         current_idx += timestamp_len;
         let raw_data = &slice[0..total_len];
-        let pus_tm = PusTm {
+        let pus_tm = Self {
             sp_header,
             sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper).unwrap(),
-            raw_data: Some(&slice[0..total_len]),
+            raw_data: &slice[0..total_len],
             source_data: user_data_from_raw(current_idx, total_len, raw_data_len, slice)?,
-            calc_crc_on_serialization: false,
-            crc16: Some(crc_from_raw_data(raw_data)?),
+            crc16: crc_from_raw_data(raw_data)?,
         };
-        verify_crc16_ccitt_false_from_raw_to_pus_error(
-            raw_data,
-            pus_tm.crc16.expect("CRC16 invalid"),
-        )?;
+        verify_crc16_ccitt_false_from_raw_to_pus_error(raw_data, pus_tm.crc16)?;
         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]> {
+    pub fn len_packed(&self) -> usize {
+        self.sp_header.total_len()
+    }
+
+    pub fn source_data(&self) -> &[u8] {
+        self.user_data()
+    }
+
+    pub fn timestamp(&self) -> &[u8] {
+        self.sec_header.timestamp
+    }
+
+    /// This function will return the slice [Self] was constructed from.
+    pub fn raw_data(&self) -> &[u8] {
         self.raw_data
     }
 }
 
+impl PartialEq for PusTmReader<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.raw_data == other.raw_data
+    }
+}
+
+impl CcsdsPacket for PusTmReader<'_> {
+    ccsds_impl!();
+}
+
+impl PusPacket for PusTmReader<'_> {
+    delegate!(to self.sec_header {
+        fn pus_version(&self) -> PusVersion;
+        fn service(&self) -> u8;
+        fn subservice(&self) -> u8;
+    });
+
+    fn user_data(&self) -> &[u8] {
+        self.source_data
+    }
+
+    fn crc16(&self) -> Option<u16> {
+        Some(self.crc16)
+    }
+}
+
+impl GenericPusTmSecondaryHeader for PusTmReader<'_> {
+    delegate!(to self.sec_header {
+        fn pus_version(&self) -> PusVersion;
+        fn service(&self) -> u8;
+        fn subservice(&self) -> u8;
+        fn dest_id(&self) -> u16;
+        fn msg_counter(&self) -> u16;
+        fn sc_time_ref_status(&self) -> u8;
+    });
+}
+
+impl IsPusTelemetry for PusTmReader<'_> {}
+
+impl PartialEq<PusTmCreator<'_>> for PusTmReader<'_> {
+    fn eq(&self, other: &PusTmCreator<'_>) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.source_data == other.source_data
+    }
+}
+
+impl PartialEq<PusTmReader<'_>> for PusTmCreator<'_> {
+    fn eq(&self, other: &PusTmReader<'_>) -> bool {
+        self.sp_header == other.sp_header
+            && self.sec_header == other.sec_header
+            && self.source_data == other.source_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.
@@ -479,117 +941,22 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
     }
 }
 
-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
-impl CcsdsPacket for PusTm<'_> {
-    ccsds_impl!();
-}
-
-//noinspection RsTraitImplementation
-impl PusPacket for PusTm<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-    });
-
-    fn user_data(&self) -> Option<&[u8]> {
-        self.source_data
-    }
-
-    fn crc16(&self) -> Option<u16> {
-        self.crc16
-    }
-}
-
-//noinspection RsTraitImplementation
-impl GenericPusTmSecondaryHeader for PusTm<'_> {
-    delegate!(to self.sec_header {
-        fn pus_version(&self) -> PusVersion;
-        fn service(&self) -> u8;
-        fn subservice(&self) -> u8;
-        fn dest_id(&self) -> u16;
-        fn msg_counter(&self) -> u16;
-        fn sc_time_ref_status(&self) -> u8;
-    });
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::ecss::PusVersion::PusC;
     use crate::SpHeader;
 
-    fn base_ping_reply_full_ctor(timestamp: &[u8]) -> PusTm {
+    fn base_ping_reply_full_ctor(timestamp: &[u8]) -> PusTmCreator {
         let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
         let tm_header = PusTmSecondaryHeader::new_simple(17, 2, &timestamp);
-        PusTm::new(&mut sph, tm_header, None, true)
+        PusTmCreator::new(&mut sph, tm_header, None, true)
     }
 
-    fn base_hk_reply<'a>(timestamp: &'a [u8], src_data: &'a [u8]) -> PusTm<'a> {
+    fn base_hk_reply<'a>(timestamp: &'a [u8], src_data: &'a [u8]) -> PusTmCreator<'a> {
         let mut sph = SpHeader::tm_unseg(0x123, 0x234, 0).unwrap();
         let tc_header = PusTmSecondaryHeader::new_simple(3, 5, &timestamp);
-        PusTm::new(&mut sph, tc_header, Some(src_data), true)
+        PusTmCreator::new(&mut sph, tc_header, Some(src_data), true)
     }
 
     fn dummy_timestamp() -> &'static [u8] {
@@ -652,22 +1019,19 @@ mod tests {
             .write_to_bytes(&mut buf)
             .expect("Serialization failed");
         assert_eq!(ser_len, 22);
-        let (tm_deserialized, size) = PusTm::from_bytes(&buf, 7).expect("Deserialization failed");
+        let (tm_deserialized, size) = PusTmReader::new(&buf, 7).expect("Deserialization failed");
         assert_eq!(ser_len, size);
-        verify_ping_reply(&tm_deserialized, false, 22, dummy_timestamp());
+        verify_ping_reply_with_reader(&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_timestamp());
-        let mut tm = PusTm::new(&mut sph, tc_header, None, false);
+        let mut tm = PusTmCreator::new(&mut sph, tc_header, None, false);
         tm.calc_crc_on_serialization = false;
         assert_eq!(tm.data_len(), 0x00);
         let mut buf: [u8; 32] = [0; 32];
-        let res = tm.write_to_bytes(&mut buf);
-        assert!(res.is_err());
-        assert!(matches!(res.unwrap_err(), PusError::CrcCalculationMissing));
         tm.update_ccsds_data_len();
         assert_eq!(tm.data_len(), 15);
         tm.calc_own_crc16();
@@ -686,12 +1050,12 @@ mod tests {
         let res = pus_tm.write_to_bytes(&mut buf);
         assert!(res.is_err());
         let error = res.unwrap_err();
-        assert!(matches!(error, PusError::ByteConversionError { .. }));
+        assert!(matches!(error, PusError::ByteConversion { .. }));
         match error {
-            PusError::ByteConversionError(err) => match err {
-                ByteConversionError::ToSliceTooSmall(size_missmatch) => {
-                    assert_eq!(size_missmatch.expected, 22);
-                    assert_eq!(size_missmatch.found, 16);
+            PusError::ByteConversion(err) => match err {
+                ByteConversionError::ToSliceTooSmall { found, expected } => {
+                    assert_eq!(expected, 22);
+                    assert_eq!(found, 16);
                 }
                 _ => panic!("Invalid PUS error {:?}", err),
             },
@@ -755,19 +1119,38 @@ mod tests {
     }
 
     fn verify_ping_reply(
-        tm: &PusTm,
+        tm: &PusTmCreator,
         has_user_data: bool,
         exp_full_len: usize,
         exp_timestamp: &[u8],
+    ) {
+        assert_eq!(tm.len_packed(), exp_full_len);
+        assert_eq!(tm.timestamp(), exp_timestamp);
+        verify_ping_reply_generic(tm, has_user_data, exp_full_len);
+    }
+
+    fn verify_ping_reply_with_reader(
+        tm: &PusTmReader,
+        has_user_data: bool,
+        exp_full_len: usize,
+        exp_timestamp: &[u8],
+    ) {
+        assert_eq!(tm.len_packed(), exp_full_len);
+        assert_eq!(tm.timestamp(), exp_timestamp);
+        verify_ping_reply_generic(tm, has_user_data, exp_full_len);
+    }
+
+    fn verify_ping_reply_generic(
+        tm: &(impl CcsdsPacket + GenericPusTmSecondaryHeader + PusPacket),
+        has_user_data: bool,
+        exp_full_len: usize,
     ) {
         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.timestamp().unwrap(), exp_timestamp);
         if has_user_data {
-            assert!(!tm.user_data().is_none());
+            assert!(!tm.user_data().is_empty());
         }
         assert_eq!(PusPacket::pus_version(tm), PusC);
         assert_eq!(tm.apid(), 0x123);
@@ -792,7 +1175,7 @@ mod tests {
         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);
+        assert_eq!(pus_tm, PusTmReader::new(&buf, timestamp.len()).unwrap().0);
     }
 
     #[test]
@@ -811,7 +1194,7 @@ mod tests {
         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");
+            PusTmReader::new(&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);

src/lib.rs

@@ -65,8 +65,7 @@ use crate::ecss::CCSDS_HEADER_LEN;
 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;
 
@@ -75,9 +74,7 @@ use serde::{Deserialize, Serialize};
 
 pub mod cfdp;
 pub mod ecss;
-pub mod tc;
 pub mod time;
-pub mod tm;
 pub mod util;
 
 mod private {
@@ -90,20 +87,20 @@ 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;
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
-#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-pub struct SizeMissmatch {
-    pub found: usize,
-    pub expected: usize,
-}
-
+/// Generic error type when converting to and from raw byte slices.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 pub enum ByteConversionError {
     /// The passed slice is too small. Returns the passed slice length and expected minimum size
-    ToSliceTooSmall(SizeMissmatch),
+    ToSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
     /// The provider buffer is too small. Returns the passed slice length and expected minimum size
-    FromSliceTooSmall(SizeMissmatch),
+    FromSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
     /// The [zerocopy] library failed to write to bytes
     ZeroCopyToError,
     ZeroCopyFromError,
@@ -112,18 +109,18 @@ pub enum ByteConversionError {
 impl Display for ByteConversionError {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         match self {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
                 write!(
                     f,
                     "target slice with size {} is too small, expected size of at least {}",
-                    missmatch.found, missmatch.expected
+                    found, expected
                 )
             }
-            ByteConversionError::FromSliceTooSmall(missmatch) => {
+            ByteConversionError::FromSliceTooSmall { found, expected } => {
                 write!(
                     f,
                     "source slice with size {} too small, expected at least {} bytes",
-                    missmatch.found, missmatch.expected
+                    found, expected
                 )
             }
             ByteConversionError::ZeroCopyToError => {
@@ -567,10 +564,10 @@ impl SpHeader {
     /// CCSDS header.
     pub fn from_be_bytes(buf: &[u8]) -> Result<(Self, &[u8]), ByteConversionError> {
         if buf.len() < CCSDS_HEADER_LEN {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: CCSDS_HEADER_LEN,
-            }));
+            });
         }
         let zc_header = zc::SpHeader::from_bytes(&buf[0..CCSDS_HEADER_LEN])
             .ok_or(ByteConversionError::ZeroCopyFromError)?;
@@ -584,10 +581,10 @@ impl SpHeader {
         buf: &'a mut [u8],
     ) -> Result<&'a mut [u8], ByteConversionError> {
         if buf.len() < CCSDS_HEADER_LEN {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 found: buf.len(),
                 expected: CCSDS_HEADER_LEN,
-            }));
+            });
         }
         let zc_header: zc::SpHeader = zc::SpHeader::from(*self);
         zc_header
@@ -644,9 +641,9 @@ sph_from_other!(SpHeader, crate::zc::SpHeader);
 pub mod zc {
     use crate::{CcsdsPacket, CcsdsPrimaryHeader, PacketId, PacketSequenceCtrl, VERSION_MASK};
     use zerocopy::byteorder::NetworkEndian;
-    use zerocopy::{AsBytes, FromBytes, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, Unaligned, U16};
 
-    #[derive(FromBytes, AsBytes, Unaligned, Debug)]
+    #[derive(FromBytes, FromZeroes, AsBytes, Unaligned, Debug)]
     #[repr(C)]
     pub struct SpHeader {
         version_packet_id: U16<NetworkEndian>,

src/time/cds.rs

@@ -428,14 +428,17 @@ pub fn get_dyn_time_provider_from_bytes(
 ) -> Result<Box<dyn DynCdsTimeProvider>, TimestampError> {
     let time_code = ccsds_time_code_from_p_field(buf[0]);
     if let Err(e) = time_code {
-        return Err(TimestampError::InvalidTimeCode(CcsdsTimeCodes::Cds, e));
+        return Err(TimestampError::InvalidTimeCode {
+            expected: CcsdsTimeCodes::Cds,
+            found: e,
+        });
     }
     let time_code = time_code.unwrap();
     if time_code != CcsdsTimeCodes::Cds {
-        return Err(TimestampError::InvalidTimeCode(
-            CcsdsTimeCodes::Cds,
-            time_code as u8,
-        ));
+        return Err(TimestampError::InvalidTimeCode {
+            expected: CcsdsTimeCodes::Cds,
+            found: time_code as u8,
+        });
     }
     if length_of_day_segment_from_pfield(buf[0]) == LengthOfDaySegment::Short16Bits {
         Ok(Box::new(TimeProvider::from_bytes_with_u16_days(buf)?))
@@ -511,11 +514,11 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
         days_len: LengthOfDaySegment,
     ) -> Result<SubmillisPrecision, TimestampError> {
         if buf.len() < MIN_CDS_FIELD_LEN {
-            return Err(TimestampError::ByteConversionError(
-                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(TimestampError::ByteConversion(
+                ByteConversionError::FromSliceTooSmall {
                     expected: MIN_CDS_FIELD_LEN,
                     found: buf.len(),
-                }),
+                },
             ));
         }
         let pfield = buf[0];
@@ -523,17 +526,17 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
             Ok(cds_type) => match cds_type {
                 CcsdsTimeCodes::Cds => (),
                 _ => {
-                    return Err(TimestampError::InvalidTimeCode(
-                        CcsdsTimeCodes::Cds,
-                        cds_type as u8,
-                    ))
+                    return Err(TimestampError::InvalidTimeCode {
+                        expected: CcsdsTimeCodes::Cds,
+                        found: cds_type as u8,
+                    })
                 }
             },
             _ => {
-                return Err(TimestampError::InvalidTimeCode(
-                    CcsdsTimeCodes::Cds,
-                    pfield >> 4 & 0b111,
-                ))
+                return Err(TimestampError::InvalidTimeCode {
+                    expected: CcsdsTimeCodes::Cds,
+                    found: pfield >> 4 & 0b111,
+                });
             }
         };
         if ((pfield >> 3) & 0b1) == 1 {
@@ -545,11 +548,11 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
         }
         let stamp_len = Self::calc_stamp_len(pfield);
         if buf.len() < stamp_len {
-            return Err(TimestampError::ByteConversionError(
-                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(TimestampError::ByteConversion(
+                ByteConversionError::FromSliceTooSmall {
                     expected: stamp_len,
                     found: buf.len(),
-                }),
+                },
             ));
         }
         Ok(precision_from_pfield(pfield))
@@ -602,11 +605,11 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
 
     fn length_check(&self, buf: &[u8], len_as_bytes: usize) -> Result<(), TimestampError> {
         if buf.len() < len_as_bytes {
-            return Err(TimestampError::ByteConversionError(
-                ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(TimestampError::ByteConversion(
+                ByteConversionError::ToSliceTooSmall {
                     expected: len_as_bytes,
                     found: buf.len(),
-                }),
+                },
             ));
         }
         Ok(())
@@ -671,21 +674,21 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
     fn from_now_generic(days_len: LengthOfDaySegment) -> Result<Self, StdTimestampError> {
         let conversion_from_now = ConversionFromNow::new()?;
         Self::generic_from_conversion(days_len, conversion_from_now)
-            .map_err(StdTimestampError::TimestampError)
+            .map_err(StdTimestampError::Timestamp)
     }
 
     #[cfg(feature = "std")]
     fn from_now_generic_us_prec(days_len: LengthOfDaySegment) -> Result<Self, StdTimestampError> {
         let conversion_from_now = ConversionFromNow::new_with_submillis_us_prec()?;
         Self::generic_from_conversion(days_len, conversion_from_now)
-            .map_err(StdTimestampError::TimestampError)
+            .map_err(StdTimestampError::Timestamp)
     }
 
     #[cfg(feature = "std")]
     fn from_now_generic_ps_prec(days_len: LengthOfDaySegment) -> Result<Self, StdTimestampError> {
         let conversion_from_now = ConversionFromNow::new_with_submillis_ps_prec()?;
         Self::generic_from_conversion(days_len, conversion_from_now)
-            .map_err(StdTimestampError::TimestampError)
+            .map_err(StdTimestampError::Timestamp)
     }
 
     fn generic_from_conversion<C: CdsConverter>(
@@ -694,7 +697,7 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
     ) -> Result<Self, TimestampError> {
         let ccsds_days: ProvidesDaysLen::FieldType =
             converter.ccsds_days_as_u32().try_into().map_err(|_| {
-                TimestampError::CdsError(CdsError::InvalidCcsdsDays(
+                TimestampError::Cds(CdsError::InvalidCcsdsDays(
                     converter.ccsds_days_as_u32().into(),
                 ))
             })?;
@@ -750,7 +753,7 @@ impl<ProvidesDaysLen: ProvidesDaysLength> TimeProvider<ProvidesDaysLen> {
             .ccsds_days
             .try_into()
             .map_err(|_| {
-                StdTimestampError::TimestampError(
+                StdTimestampError::Timestamp(
                     CdsError::InvalidCcsdsDays(
                         conversion_from_now.unix_conversion.ccsds_days as i64,
                     )
@@ -788,7 +791,7 @@ impl TimeProvider<DaysLen24Bits> {
     /// ## Errors
     ///
     /// This function will return [TimestampError::DateBeforeCcsdsEpoch] or
-    /// [TimestampError::CdsError] if the time is before the CCSDS epoch (1958-01-01T00:00:00+00:00)
+    /// [TimestampError::Cds] if the time is before the CCSDS epoch (1958-01-01T00:00:00+00:00)
     /// or the CCSDS days value exceeds the allowed bit width (24 bits).
     pub fn from_dt_with_u24_days(dt: &DateTime<Utc>) -> Result<Self, TimestampError> {
         Self::from_dt_generic(dt, LengthOfDaySegment::Long24Bits)
@@ -799,7 +802,7 @@ impl TimeProvider<DaysLen24Bits> {
     /// ## Errors
     ///
     /// This function will return [TimestampError::DateBeforeCcsdsEpoch] or
-    /// [TimestampError::CdsError] if the time is before the CCSDS epoch (1958-01-01T00:00:00+00:00)
+    /// [TimestampError::Cds] if the time is before the CCSDS epoch (1958-01-01T00:00:00+00:00)
     /// or the CCSDS days value exceeds the allowed bit width (24 bits).
     pub fn from_unix_secs_with_u24_days(
         unix_stamp: &UnixTimestamp,
@@ -864,7 +867,7 @@ impl TimeProvider<DaysLen16Bits> {
     /// Create a provider from a [`DateTime<Utc>`] struct.
     ///
     /// This function will return a [TimestampError::DateBeforeCcsdsEpoch] or a
-    /// [TimestampError::CdsError] if the time is before the CCSDS epoch (01-01-1958 00:00:00) or
+    /// [TimestampError::Cds] if the time is before the CCSDS epoch (01-01-1958 00:00:00) or
     /// the CCSDS days value exceeds the allowed bit width (16 bits).
     pub fn from_dt_with_u16_days(dt: &DateTime<Utc>) -> Result<Self, TimestampError> {
         Self::from_dt_generic(dt, LengthOfDaySegment::Short16Bits)
@@ -882,7 +885,7 @@ impl TimeProvider<DaysLen16Bits> {
     /// ## Errors
     ///
     /// This function will return [TimestampError::DateBeforeCcsdsEpoch] or
-    /// [TimestampError::CdsError] if the time is before the CCSDS epoch (1958-01-01T00:00:00+00:00)
+    /// [TimestampError::Cds] if the time is before the CCSDS epoch (1958-01-01T00:00:00+00:00)
     /// or the CCSDS days value exceeds the allowed bit width (24 bits).
     pub fn from_unix_secs_with_u16_days(
         unix_stamp: &UnixTimestamp,
@@ -1302,7 +1305,7 @@ impl TryFrom<TimeProvider<DaysLen24Bits>> for TimeProvider<DaysLen16Bits> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::time::TimestampError::{ByteConversionError, InvalidTimeCode};
+    use crate::time::TimestampError::{ByteConversion, InvalidTimeCode};
     use crate::ByteConversionError::{FromSliceTooSmall, ToSliceTooSmall};
     use chrono::{Datelike, NaiveDate, Timelike};
     #[cfg(feature = "serde")]
@@ -1400,8 +1403,7 @@ mod tests {
         let faulty_ctor = TimeProvider::<DaysLen16Bits>::from_bytes(&buf);
         assert!(faulty_ctor.is_err());
         let error = faulty_ctor.unwrap_err();
-        if let TimestampError::CdsError(CdsError::InvalidCtorForDaysOfLenInPreamble(len_of_day)) =
-            error
+        if let TimestampError::Cds(CdsError::InvalidCtorForDaysOfLenInPreamble(len_of_day)) = error
         {
             assert_eq!(len_of_day, LengthOfDaySegment::Long24Bits);
         } else {
@@ -1446,9 +1448,9 @@ mod tests {
             let res = time_stamper.write_to_bytes(&mut buf[0..i]);
             assert!(res.is_err());
             match res.unwrap_err() {
-                ByteConversionError(ToSliceTooSmall(missmatch)) => {
-                    assert_eq!(missmatch.found, i);
-                    assert_eq!(missmatch.expected, 7);
+                ByteConversion(ToSliceTooSmall { found, expected }) => {
+                    assert_eq!(found, i);
+                    assert_eq!(expected, 7);
                 }
                 _ => panic!(
                     "{}",
@@ -1466,10 +1468,10 @@ mod tests {
             assert!(res.is_err());
             let err = res.unwrap_err();
             match err {
-                ByteConversionError(e) => match e {
-                    FromSliceTooSmall(missmatch) => {
-                        assert_eq!(missmatch.found, i);
-                        assert_eq!(missmatch.expected, 7);
+                ByteConversion(e) => match e {
+                    FromSliceTooSmall { found, expected } => {
+                        assert_eq!(found, i);
+                        assert_eq!(expected, 7);
                     }
                     _ => panic!("{}", format!("Invalid error {:?} detected", e)),
                 },
@@ -1491,9 +1493,9 @@ mod tests {
         assert!(res.is_err());
         let err = res.unwrap_err();
         match err {
-            InvalidTimeCode(code, raw) => {
-                assert_eq!(code, CcsdsTimeCodes::Cds);
-                assert_eq!(raw, 0);
+            InvalidTimeCode { expected, found } => {
+                assert_eq!(expected, CcsdsTimeCodes::Cds);
+                assert_eq!(found, 0);
             }
             _ => {}
         }
@@ -1762,7 +1764,7 @@ mod tests {
     fn generic_dt_case_1_us_prec(subsec_millis: u32) -> DateTime<Utc> {
         // 250 ms + 500 us
         let subsec_micros = subsec_millis * 1000 + 500;
-        let naivedatetime_utc = NaiveDate::from_ymd_opt(2023, 01, 14)
+        let naivedatetime_utc = NaiveDate::from_ymd_opt(2023, 1, 14)
             .unwrap()
             .and_hms_micro_opt(16, 49, 30, subsec_micros)
             .unwrap();
@@ -1813,7 +1815,7 @@ mod tests {
         // 250 ms + 500 us
         let subsec_nanos = subsec_millis * 1000 * 1000 + 500 * 1000;
         let submilli_nanos = subsec_nanos % 10_u32.pow(6);
-        let naivedatetime_utc = NaiveDate::from_ymd_opt(2023, 01, 14)
+        let naivedatetime_utc = NaiveDate::from_ymd_opt(2023, 1, 14)
             .unwrap()
             .and_hms_nano_opt(16, 49, 30, subsec_nanos)
             .unwrap();
@@ -1943,7 +1945,7 @@ mod tests {
                 panic!("creation should not succeed")
             }
             Err(e) => {
-                if let TimestampError::CdsError(CdsError::InvalidCcsdsDays(days)) = e {
+                if let TimestampError::Cds(CdsError::InvalidCcsdsDays(days)) = e {
                     assert_eq!(
                         days,
                         unix_to_ccsds_days(invalid_unix_secs / SECONDS_PER_DAY as i64)

src/time/cuc.rs

@@ -244,7 +244,7 @@ impl TimeProviderCcsdsEpoch {
         let fractions =
             fractional_part_from_subsec_ns(fraction_resolution, now.subsec_nanos() as u64);
         Self::new_with_fractions(ccsds_epoch as u32, fractions.unwrap())
-            .map_err(|e| StdTimestampError::TimestampError(e.into()))
+            .map_err(|e| StdTimestampError::Timestamp(e.into()))
     }
 
     /// Updates the current time stamp from the current time. The fractional field width remains
@@ -453,37 +453,37 @@ impl TimeReader for TimeProviderCcsdsEpoch {
         Self: Sized,
     {
         if buf.len() < MIN_CUC_LEN {
-            return Err(TimestampError::ByteConversionError(
-                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(TimestampError::ByteConversion(
+                ByteConversionError::FromSliceTooSmall {
                     expected: MIN_CUC_LEN,
                     found: buf.len(),
-                }),
+                },
             ));
         }
         match ccsds_time_code_from_p_field(buf[0]) {
             Ok(code) => {
                 if code != CcsdsTimeCodes::CucCcsdsEpoch {
-                    return Err(TimestampError::InvalidTimeCode(
-                        CcsdsTimeCodes::CucCcsdsEpoch,
-                        code as u8,
-                    ));
+                    return Err(TimestampError::InvalidTimeCode {
+                        expected: CcsdsTimeCodes::CucCcsdsEpoch,
+                        found: code as u8,
+                    });
                 }
             }
             Err(raw) => {
-                return Err(TimestampError::InvalidTimeCode(
-                    CcsdsTimeCodes::CucCcsdsEpoch,
-                    raw,
-                ))
+                return Err(TimestampError::InvalidTimeCode {
+                    expected: CcsdsTimeCodes::CucCcsdsEpoch,
+                    found: raw,
+                });
             }
         }
         let (cntr_len, fractions_len, total_len) =
             Self::len_components_and_total_from_pfield(buf[0]);
         if buf.len() < total_len {
-            return Err(TimestampError::ByteConversionError(
-                ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(TimestampError::ByteConversion(
+                ByteConversionError::FromSliceTooSmall {
                     expected: total_len,
                     found: buf.len(),
-                }),
+                },
             ));
         }
         let mut current_idx = 1;
@@ -535,11 +535,11 @@ impl TimeWriter for TimeProviderCcsdsEpoch {
     fn write_to_bytes(&self, bytes: &mut [u8]) -> Result<usize, TimestampError> {
         // Cross check the sizes of the counters against byte widths in the ctor
         if bytes.len() < self.len_as_bytes() {
-            return Err(TimestampError::ByteConversionError(
-                ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(TimestampError::ByteConversion(
+                ByteConversionError::ToSliceTooSmall {
                     found: bytes.len(),
                     expected: self.len_as_bytes(),
-                }),
+                },
             ));
         }
         bytes[0] = self.pfield;
@@ -797,11 +797,13 @@ mod tests {
             let res = TimeProviderCcsdsEpoch::from_bytes(&buf[0..i]);
             assert!(res.is_err());
             let err = res.unwrap_err();
-            if let TimestampError::ByteConversionError(ByteConversionError::FromSliceTooSmall(e)) =
-                err
+            if let TimestampError::ByteConversion(ByteConversionError::FromSliceTooSmall {
+                found,
+                expected,
+            }) = err
             {
-                assert_eq!(e.found, i);
-                assert_eq!(e.expected, 2);
+                assert_eq!(found, i);
+                assert_eq!(expected, 2);
             }
         }
         let large_stamp = TimeProviderCcsdsEpoch::new_with_fine_fractions(22, 300).unwrap();
@@ -810,11 +812,13 @@ mod tests {
             let res = TimeProviderCcsdsEpoch::from_bytes(&buf[0..i]);
             assert!(res.is_err());
             let err = res.unwrap_err();
-            if let TimestampError::ByteConversionError(ByteConversionError::FromSliceTooSmall(e)) =
-                err
+            if let TimestampError::ByteConversion(ByteConversionError::FromSliceTooSmall {
+                found,
+                expected,
+            }) = err
             {
-                assert_eq!(e.found, i);
-                assert_eq!(e.expected, large_stamp.len_as_bytes());
+                assert_eq!(found, i);
+                assert_eq!(expected, large_stamp.len_as_bytes());
             }
         }
     }
@@ -886,11 +890,13 @@ mod tests {
             let err = cuc.write_to_bytes(&mut buf[0..i]);
             assert!(err.is_err());
             let err = err.unwrap_err();
-            if let TimestampError::ByteConversionError(ByteConversionError::ToSliceTooSmall(e)) =
-                err
+            if let TimestampError::ByteConversion(ByteConversionError::ToSliceTooSmall {
+                found,
+                expected,
+            }) = err
             {
-                assert_eq!(e.expected, cuc.len_as_bytes());
-                assert_eq!(e.found, i);
+                assert_eq!(expected, cuc.len_as_bytes());
+                assert_eq!(found, i);
             } else {
                 panic!("unexpected error: {}", err);
             }
@@ -903,9 +909,9 @@ mod tests {
         let res = TimeProviderCcsdsEpoch::from_bytes(&buf);
         assert!(res.is_err());
         let err = res.unwrap_err();
-        if let TimestampError::InvalidTimeCode(code, raw) = err {
-            assert_eq!(code, CcsdsTimeCodes::CucCcsdsEpoch);
-            assert_eq!(raw, CcsdsTimeCodes::CucAgencyEpoch as u8);
+        if let TimestampError::InvalidTimeCode { expected, found } = err {
+            assert_eq!(expected, CcsdsTimeCodes::CucCcsdsEpoch);
+            assert_eq!(found, CcsdsTimeCodes::CucAgencyEpoch as u8);
         } else {
             panic!("unexpected error: {}", err);
         }

src/time/mod.rs

@@ -1,10 +1,11 @@
 //! CCSDS Time Code Formats according to [CCSDS 301.0-B-4](https://public.ccsds.org/Pubs/301x0b4e1.pdf)
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 use chrono::{DateTime, LocalResult, TimeZone, Utc};
 use core::cmp::Ordering;
 use core::fmt::{Display, Formatter};
 use core::ops::{Add, AddAssign};
 use core::time::Duration;
+use core::u8;
 
 #[allow(unused_imports)]
 #[cfg(not(feature = "std"))]
@@ -16,6 +17,8 @@ use serde::{Deserialize, Serialize};
 use std::error::Error;
 #[cfg(feature = "std")]
 use std::time::{SystemTime, SystemTimeError};
+#[cfg(feature = "std")]
+pub use std_mod::*;
 
 pub mod ascii;
 pub mod cds;
@@ -61,66 +64,30 @@ pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCodes, u8> {
 #[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
-    InvalidTimeCode(CcsdsTimeCodes, u8),
-    ByteConversionError(ByteConversionError),
-    CdsError(cds::CdsError),
-    CucError(cuc::CucError),
+    InvalidTimeCode { expected: CcsdsTimeCodes, found: u8 },
+    ByteConversion(ByteConversionError),
+    Cds(cds::CdsError),
+    Cuc(cuc::CucError),
     DateBeforeCcsdsEpoch(DateTime<Utc>),
     CustomEpochNotSupported,
 }
 
-impl From<cds::CdsError> for TimestampError {
-    fn from(e: cds::CdsError) -> Self {
-        TimestampError::CdsError(e)
-    }
-}
-
-impl From<cuc::CucError> for TimestampError {
-    fn from(e: cuc::CucError) -> Self {
-        TimestampError::CucError(e)
-    }
-}
-
-#[cfg(feature = "std")]
-#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
-#[derive(Debug, Clone)]
-pub enum StdTimestampError {
-    SystemTimeError(SystemTimeError),
-    TimestampError(TimestampError),
-}
-
-#[cfg(feature = "std")]
-impl From<TimestampError> for StdTimestampError {
-    fn from(v: TimestampError) -> Self {
-        Self::TimestampError(v)
-    }
-}
-
-#[cfg(feature = "std")]
-impl From<SystemTimeError> for StdTimestampError {
-    fn from(v: SystemTimeError) -> Self {
-        Self::SystemTimeError(v)
-    }
-}
-
 impl Display for TimestampError {
     fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
         match self {
-            TimestampError::InvalidTimeCode(time_code, raw_val) => {
+            TimestampError::InvalidTimeCode { expected, found } => {
                 write!(
                     f,
-                    "invalid raw time code value {raw_val} for time code {time_code:?}"
+                    "invalid raw time code value {found} for time code {expected:?}"
                 )
             }
-            TimestampError::CdsError(e) => {
+            TimestampError::Cds(e) => {
                 write!(f, "cds error {e}")
             }
-            TimestampError::CucError(e) => {
+            TimestampError::Cuc(e) => {
                 write!(f, "cuc error {e}")
             }
-            TimestampError::ByteConversionError(e) => {
+            TimestampError::ByteConversion(e) => {
                 write!(f, "byte conversion error {e}")
             }
             TimestampError::DateBeforeCcsdsEpoch(e) => {
@@ -137,13 +104,40 @@ impl Display for TimestampError {
 impl Error for TimestampError {
     fn source(&self) -> Option<&(dyn Error + 'static)> {
         match self {
-            TimestampError::ByteConversionError(e) => Some(e),
-            TimestampError::CdsError(e) => Some(e),
-            TimestampError::CucError(e) => Some(e),
+            TimestampError::ByteConversion(e) => Some(e),
+            TimestampError::Cds(e) => Some(e),
+            TimestampError::Cuc(e) => Some(e),
             _ => None,
         }
     }
 }
+impl From<cds::CdsError> for TimestampError {
+    fn from(e: cds::CdsError) -> Self {
+        TimestampError::Cds(e)
+    }
+}
+
+impl From<cuc::CucError> for TimestampError {
+    fn from(e: cuc::CucError) -> Self {
+        TimestampError::Cuc(e)
+    }
+}
+
+#[cfg(feature = "std")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]
+pub mod std_mod {
+    use crate::time::TimestampError;
+    use std::time::SystemTimeError;
+    use thiserror::Error;
+
+    #[derive(Debug, Clone, Error)]
+    pub enum StdTimestampError {
+        #[error("system time error: {0}")]
+        SystemTime(#[from] SystemTimeError),
+        #[error("timestamp error: {0}")]
+        Timestamp(#[from] TimestampError),
+    }
+}
 
 #[cfg(feature = "std")]
 #[cfg_attr(doc_cfg, doc(cfg(feature = "std")))]

src/util.rs

@@ -1,4 +1,4 @@
-use crate::{ByteConversionError, SizeMissmatch};
+use crate::ByteConversionError;
 use core::fmt::{Debug, Display, Formatter};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
@@ -80,12 +80,17 @@ 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)),
+    /// Value is too large for specified width of byte field.
+    ValueTooLargeForWidth {
+        width: usize,
+        value: u64,
+    },
     /// Only 1, 2, 4 and 8 are allow width values. Optionally contains the expected width if
     /// applicable, for example for conversions.
-    InvalidWidth(usize, Option<usize>),
+    InvalidWidth {
+        found: usize,
+        expected: Option<usize>,
+    },
     ByteConversionError(ByteConversionError),
 }
 
@@ -101,10 +106,10 @@ impl Display for UnsignedByteFieldError {
             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::InvalidWidth { found, .. } => {
+                write!(f, "invalid width {found}, only 1, 2, 4 and 8 are allowed.")
             }
-            Self::ValueTooLargeForWidth((width, value)) => {
+            Self::ValueTooLargeForWidth { width, value } => {
                 write!(f, "value {value} too large for width {width}")
             }
         }
@@ -123,7 +128,7 @@ pub struct UnsignedByteField {
 }
 
 impl UnsignedByteField {
-    pub fn new(width: usize, value: u64) -> Self {
+    pub const fn new(width: usize, value: u64) -> Self {
         Self { width, value }
     }
 
@@ -133,10 +138,10 @@ impl UnsignedByteField {
 
     pub fn new_from_be_bytes(width: usize, buf: &[u8]) -> Result<Self, UnsignedByteFieldError> {
         if width > buf.len() {
-            return Err(ByteConversionError::FromSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::FromSliceTooSmall {
                 expected: width,
                 found: buf.len(),
-            })
+            }
             .into());
         }
         match width {
@@ -154,7 +159,10 @@ impl UnsignedByteField {
                 width,
                 u64::from_be_bytes(buf[0..8].try_into().unwrap()),
             )),
-            _ => Err(UnsignedByteFieldError::InvalidWidth(width, None)),
+            _ => Err(UnsignedByteFieldError::InvalidWidth {
+                found: width,
+                expected: None,
+            }),
         }
     }
 }
@@ -166,10 +174,10 @@ impl UnsignedEnum for UnsignedByteField {
 
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.size() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 expected: self.size(),
                 found: buf.len(),
-            }));
+            });
         }
         match self.size() {
             0 => Ok(0),
@@ -204,7 +212,7 @@ pub struct GenericUnsignedByteField<TYPE> {
 }
 
 impl<TYPE> GenericUnsignedByteField<TYPE> {
-    pub fn new(val: TYPE) -> Self {
+    pub const fn new(val: TYPE) -> Self {
         Self { value: val }
     }
 }
@@ -216,10 +224,10 @@ impl<TYPE: ToBeBytes> UnsignedEnum for GenericUnsignedByteField<TYPE> {
 
     fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
         if buf.len() < self.size() {
-            return Err(ByteConversionError::ToSliceTooSmall(SizeMissmatch {
+            return Err(ByteConversionError::ToSliceTooSmall {
                 found: buf.len(),
                 expected: self.size(),
-            }));
+            });
         }
         buf[0..self.size()].copy_from_slice(self.value.to_be_bytes().as_ref());
         Ok(self.value.written_len())
@@ -248,7 +256,10 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU8 {
 
     fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
         if value.width != 1 {
-            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(1)));
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(1),
+            });
         }
         Ok(Self::new(value.value as u8))
     }
@@ -265,7 +276,10 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU16 {
 
     fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
         if value.width != 2 {
-            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(2)));
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(2),
+            });
         }
         Ok(Self::new(value.value as u16))
     }
@@ -282,7 +296,10 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU32 {
 
     fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
         if value.width != 4 {
-            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(4)));
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(4),
+            });
         }
         Ok(Self::new(value.value as u32))
     }
@@ -299,7 +316,10 @@ impl TryFrom<UnsignedByteField> for UnsignedByteFieldU64 {
 
     fn try_from(value: UnsignedByteField) -> Result<Self, Self::Error> {
         if value.width != 8 {
-            return Err(UnsignedByteFieldError::InvalidWidth(value.width, Some(8)));
+            return Err(UnsignedByteFieldError::InvalidWidth {
+                found: value.width,
+                expected: Some(8),
+            });
         }
         Ok(Self::new(value.value))
     }
@@ -393,8 +413,11 @@ pub mod tests {
         assert!(conv_fails.is_err());
         let err = conv_fails.unwrap_err();
         match err {
-            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
-                assert_eq!(width, 2);
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 2);
                 assert_eq!(expected, 1);
             }
             _ => {
@@ -422,8 +445,11 @@ pub mod tests {
         assert!(conv_fails.is_err());
         let err = conv_fails.unwrap_err();
         match err {
-            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
-                assert_eq!(width, 4);
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 4);
                 assert_eq!(expected, 2);
             }
             _ => {
@@ -451,8 +477,11 @@ pub mod tests {
         assert!(conv_fails.is_err());
         let err = conv_fails.unwrap_err();
         match err {
-            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
-                assert_eq!(width, 8);
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 8);
                 assert_eq!(expected, 4);
             }
             _ => {
@@ -480,8 +509,11 @@ pub mod tests {
         assert!(conv_fails.is_err());
         let err = conv_fails.unwrap_err();
         match err {
-            UnsignedByteFieldError::InvalidWidth(width, Some(expected)) => {
-                assert_eq!(width, 4);
+            UnsignedByteFieldError::InvalidWidth {
+                found,
+                expected: Some(expected),
+            } => {
+                assert_eq!(found, 4);
                 assert_eq!(expected, 8);
             }
             _ => {
@@ -582,9 +614,9 @@ pub mod tests {
         assert!(res.is_err());
         let err = res.unwrap_err();
         match err {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.found, 1);
-                assert_eq!(missmatch.expected, 2);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 1);
+                assert_eq!(expected, 2);
             }
             _ => {
                 panic!("invalid exception")
@@ -600,9 +632,9 @@ pub mod tests {
         assert!(res.is_err());
         let err = res.unwrap_err();
         match err {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.found, 1);
-                assert_eq!(missmatch.expected, 2);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 1);
+                assert_eq!(expected, 2);
             }
             _ => {
                 panic!("invalid exception {}", err)
@@ -612,11 +644,11 @@ pub mod tests {
         assert!(u16.is_err());
         let err = u16.unwrap_err();
         if let UnsignedByteFieldError::ByteConversionError(
-            ByteConversionError::FromSliceTooSmall(missmatch),
+            ByteConversionError::FromSliceTooSmall { found, expected },
         ) = err
         {
-            assert_eq!(missmatch.expected, 2);
-            assert_eq!(missmatch.found, 1);
+            assert_eq!(expected, 2);
+            assert_eq!(found, 1);
         } else {
             panic!("unexpected exception {}", err);
         }
@@ -630,9 +662,9 @@ pub mod tests {
         assert!(res.is_err());
         let err = res.unwrap_err();
         match err {
-            ByteConversionError::ToSliceTooSmall(missmatch) => {
-                assert_eq!(missmatch.found, 3);
-                assert_eq!(missmatch.expected, 4);
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                assert_eq!(found, 3);
+                assert_eq!(expected, 4);
             }
             _ => {
                 panic!("invalid exception")