Merge pull request 'Refactor ECSS packet modules' (#16) from refactoring-ecss-packet-mods into main

Reviewed-on: #16

CHANGELOG.md

@@ -8,11 +8,28 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 # [unreleased]
 
+# [v0.7.0]
+
 ## 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.
 
+## 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`.
+
 # [v0.6.0] 2023-07-06
 
 ## Added

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "spacepackets"
-version = "0.6.0"
+version = "0.7.0"
 edition = "2021"
 rust-version = "1.60"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]

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;
@@ -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]),
     }
 }
 

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);
@@ -26,13 +26,13 @@
 //! 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,
 };
@@ -49,12 +49,17 @@ 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,
@@ -77,8 +82,8 @@ 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};
 
     #[derive(FromBytes, AsBytes, Unaligned)]
@@ -90,9 +95,9 @@ 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 +211,344 @@ 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, SizeMissmatch, 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(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;
+            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 +569,10 @@ 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 +580,8 @@ 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 +628,14 @@ 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")]
@@ -340,86 +643,23 @@ 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
-    /// the instance and the found byte length of the packet.
-    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 = PusTc {
-            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<'_> {
+impl SerializablePusPacket for PusTcCreator<'_> {
     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
+        PUS_TC_MIN_LEN_WITHOUT_APP_DATA + self.app_data.len()
     }
 
     /// Write the raw PUS byte representation to a provided buffer.
@@ -442,55 +682,37 @@ impl SerializablePusPacket for PusTc<'_> {
             .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());
+        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 PartialEq for PusTc<'_> {
-    fn eq(&self, other: &Self) -> bool {
-        self.sp_header == other.sp_header
-            && self.sec_header == other.sec_header
-            && self.app_data == other.app_data
-    }
-}
-
-//noinspection RsTraitImplementation
-impl CcsdsPacket for PusTc<'_> {
+impl CcsdsPacket for PusTcCreator<'_> {
     ccsds_impl!();
 }
 
-//noinspection RsTraitImplementation
-impl PusPacket for PusTc<'_> {
+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) -> Option<&[u8]> {
+    fn user_data(&self) -> &[u8] {
         self.app_data
     }
 
     fn crc16(&self) -> Option<u16> {
-        self.crc16
+        Some(self.calc_own_crc16())
     }
 }
 
-//noinspection RsTraitImplementation
-impl GenericPusTcSecondaryHeader for PusTc<'_> {
+impl GenericPusTcSecondaryHeader for PusTcCreator<'_> {
     delegate!(to self.sec_header {
         fn pus_version(&self) -> PusVersion;
         fn service(&self) -> u8;
@@ -500,36 +722,163 @@ impl GenericPusTcSecondaryHeader for PusTc<'_> {
     });
 }
 
+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 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));
+        }
+        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,
+            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))
+    }
+
+    pub fn app_data(&self) -> &[u8] {
+        self.user_data()
+    }
+
+    pub fn raw_data(&self) -> &[u8] {
+        self.raw_data
+    }
+
+    pub fn len_packed(&self) -> usize {
+        self.sp_header.total_len()
+    }
+
+    pub fn sp_header(&self) -> &SpHeader {
+        &self.sp_header
+    }
+}
+
+impl PartialEq for PusTcReader<'_> {
+    fn eq(&self, other: &Self) -> bool {
+        self.raw_data == other.raw_data
+    }
+}
+
+impl CcsdsPacket for PusTcReader<'_> {
+    ccsds_impl!();
+}
+
+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) -> &[u8] {
+        self.app_data
+    }
+
+    fn crc16(&self) -> Option<u16> {
+        Some(self.crc16)
+    }
+}
+
+impl GenericPusTcSecondaryHeader for PusTcReader<'_> {
+    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 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 +901,10 @@ 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 +912,9 @@ 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 +926,10 @@ 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 +955,7 @@ 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 +963,7 @@ 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 +973,6 @@ 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]);
@@ -712,24 +1048,37 @@ 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 +1126,7 @@ 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

@@ -1,9 +1,9 @@
 //! 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,
@@ -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 =
@@ -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 +195,324 @@ 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, SizeMissmatch, 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(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;
+            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 +522,19 @@ 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 +555,11 @@ 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 +567,25 @@ 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 +615,20 @@ 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 +636,130 @@ 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(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;
+        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 +776,97 @@ 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))
     }
 
+    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
+    }
+
     /// 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 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 +944,22 @@ 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 +1022,19 @@ 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();
@@ -755,19 +1122,38 @@ 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 +1178,7 @@ 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 +1197,7 @@ 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

@@ -74,9 +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 {