tested basic frame parser

continue USLP support
add more USLP API
2024-10-08 16:24:16 +02:00 · 2024-10-08 15:34:47 +02:00 · 2024-10-07 17:31:11 +02:00 · 2024-10-07 15:27:45 +02:00
23 changed files with 1366 additions and 1072 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -8,46 +8,6 @@ and this project adheres to [Semantic Versioning](http://semver.org/).

 # [unreleased]

-## Added
-
- `PusTcCreatorWithReservedAppData` and `PusTmCreatorWithReservedSourceData` constructor variants
-  which allow writing source/app data into the serialization buffer directly without
-  requiring an extra buffer.
-
-# [v0.14.0] 2025-05-10
-
-## Changed
-
- Moved CRC constants/implementations to dedicated `crc` module.
- `crc::CRC_CCITT_FALSE_NO_TABLE` and `crc::CRC_CCITT_FALSE_BIG_TABLE` variants.
- Renamed `PusPacket::crc16` to `PusPacket::opt_crc16`.
-
-## Added
-
- `WritablePusPacket::write_to_bytes_crc_no_table` and `WritablePusPacket::write_to_bytes_no_crc`
-  variants.
- `PusTmReader::new_crc_no_table` and `PusTcReader::new_crc_no_table` variants.
- `crc16` methods for PUS TM and PUS TC reader.
- PUS TM and PUS TC reader now return the reader instance directly instead of a tuple of the reader
-  and the read size. The instance `total_len` method can be used to retrieve the read lenght.
-
-# [v0.13.1] 2025-03-21
-
- Bugfix due to operator precendence for `PusTcSecondaryHeader::pus_version`, 
-  `PusTcSecondaryHeaderWithoutTimestamp::pus_version`, `CdsTime::from_bytes_with_u16_days` and
-  `CdsTime::from_bytes_with_u24_days`
-
-# [v0.13.0] 2024-11-08
-
- Bumped MSRV to 1.81.0
- Bump `zerocopy` to v0.8.0
- Bump `thiserror` to v2.0.0
-
-## Changed
-
- Migrated all Error implementations to thiserror, improved some naming and error handling in
-  general
-
 # [v0.12.0] 2024-09-10

 - Bumped MSRV to 1.70.0
@ -590,9 +550,3 @@ The timestamp of `PusTm` is now optional. See Added and Changed section for deta

 Initial release with CCSDS Space Packet Primary Header implementation and basic PUS TC and TM
 implementations.
-
-[unreleased]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.14.0...HEAD
-[v0.14.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.13.1...v0.14.0
-[v0.13.1]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.13.0...v0.13.1
-[v0.13.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.12.0...v0.13.0
-[v0.12.0]: https://egit.irs.uni-stuttgart.de/rust/spacepackets/compare/v0.11.2...v0.12.0
--- a/Cargo.toml
+++ b/Cargo.toml
@ -1,6 +1,6 @@
 [package]
 name = "spacepackets"
-version = "0.14.0"
+version = "0.12.0"
 edition = "2021"
 rust-version = "1.70.0"
 authors = ["Robin Mueller <muellerr@irs.uni-stuttgart.de>"]
@ -13,29 +13,58 @@ 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]
-crc = "3.3"
+crc = "3"
 delegate = ">=0.8, <=0.13"
 paste = "1"
-zerocopy = { version = "0.8", features = ["derive"] }
-thiserror = { version = "2", default-features = false }
-num_enum = { version = ">0.5, <=0.7", default-features = false }
-num-traits = { version = "0.2", default-features = false }
-serde = { version = "1", optional = true, default-features = false, features = ["derive"] }

-time = { version = "0.3", default-features = false, optional = true }
-chrono = { version = "0.4", default-features = false, optional = true }
-defmt = { version = "1", default-features = false, optional = true }
+[dependencies.zerocopy]
+version = "0.7"
+features = ["derive"]
+
+[dependencies.thiserror]
+version = "1"
+optional = true
+
+[dependencies.num_enum]
+version = ">0.5, <=0.7"
+default-features = false
+
+[dependencies.serde]
+version = "1"
+optional = true
+default-features = false
+features = ["derive"]
+
+[dependencies.time]
+version = "0.3"
+default-features = false
+optional = true
+
+[dependencies.chrono]
+version = "0.4"
+default-features = false
+optional = true
+
+[dependencies.num-traits]
+version = "0.2"
+default-features = false
+
+[dependencies.defmt]
+version = "0.3"
+optional = true
+
+[dev-dependencies]
+postcard = "1"
+chrono = "0.4"

 [features]
 default = ["std"]
-std = ["alloc", "chrono/std", "chrono/clock", "thiserror/std"]
-serde = ["dep:serde", "chrono?/serde"]
-alloc = ["chrono?/alloc", "defmt?/alloc", "serde?/alloc"]
+std = ["chrono/std", "chrono/clock", "alloc", "thiserror"]
+serde = ["dep:serde", "chrono/serde"]
+alloc = ["postcard/alloc", "chrono/alloc", "defmt/alloc", "serde/alloc"]
+chrono = ["dep:chrono"]
 timelib = ["dep:time"]
-
-[dev-dependencies]
-postcard = { version = "1", features = ["alloc"] }
-chrono = "0.4"
+defmt = ["dep:defmt"]

 [package.metadata.docs.rs]
 all-features = true
--- a/FUNDING.yml
+++ b/FUNDING.yml
@ -1 +0,0 @@
-github: robamu
--- a/README.md
+++ b/README.md
@ -1,6 +1,7 @@
 [![Crates.io](https://img.shields.io/crates/v/spacepackets)](https://crates.io/crates/spacepackets)
 [![docs.rs](https://img.shields.io/docsrs/spacepackets)](https://docs.rs/spacepackets)
 [![ci](https://github.com/us-irs/spacepackets-rs/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/us-irs/spacepackets-rs/actions/workflows/ci.yml)
+[![coverage](https://shields.io/endpoint?url=https://absatsw.irs.uni-stuttgart.de/projects/spacepackets/coverage-rs/latest/coverage.json)](https://absatsw.irs.uni-stuttgart.de/projects/spacepackets/coverage-rs/latest/index.html)

 ECSS and CCSDS Spacepackets
 ======
--- a/docs.sh
+++ b/docs.sh
@ -1,3 +0,0 @@
-#!/bin/sh
-export RUSTDOCFLAGS="--cfg docsrs --generate-link-to-definition -Z unstable-options"
-cargo +nightly doc --all-features --open
--- a/src/cfdp/lv.rs
+++ b/src/cfdp/lv.rs
@ -6,7 +6,7 @@ use serde::{Deserialize, Serialize};
 #[cfg(feature = "std")]
 use std::string::String;

-use super::TlvLvDataTooLargeError;
+use super::TlvLvDataTooLarge;

 pub const MIN_LV_LEN: usize = 1;

@ -64,9 +64,9 @@ pub(crate) fn generic_len_check_deserialization(

 impl<'data> Lv<'data> {
    #[inline]
-    pub fn new(data: &[u8]) -> Result<Lv, TlvLvDataTooLargeError> {
+    pub fn new(data: &[u8]) -> Result<Lv, TlvLvDataTooLarge> {
        if data.len() > u8::MAX as usize {
-            return Err(TlvLvDataTooLargeError(data.len()));
+            return Err(TlvLvDataTooLarge(data.len()));
        }
        Ok(Lv {
            data,
@ -86,7 +86,7 @@ impl<'data> Lv<'data> {
    /// Helper function to build a string LV. This is especially useful for the file or directory
    /// path LVs
    #[inline]
-    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvDataTooLargeError> {
+    pub fn new_from_str(str_slice: &str) -> Result<Lv, TlvLvDataTooLarge> {
        Self::new(str_slice.as_bytes())
    }

@ -94,7 +94,7 @@ impl<'data> Lv<'data> {
    /// path LVs
    #[cfg(feature = "std")]
    #[inline]
-    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvDataTooLargeError> {
+    pub fn new_from_string(string: &'data String) -> Result<Lv<'data>, TlvLvDataTooLarge> {
        Self::new(string.as_bytes())
    }

--- a/src/cfdp/mod.rs
+++ b/src/cfdp/mod.rs
@ -1,8 +1,11 @@
 //! Low-level CCSDS File Delivery Protocol (CFDP) support according to [CCSDS 727.0-B-5](https://public.ccsds.org/Pubs/727x0b5.pdf).
 use crate::ByteConversionError;
+use core::fmt::{Display, Formatter};
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;

 pub mod lv;
 pub mod pdu;
@ -173,43 +176,97 @@ impl Default for ChecksumType {

 pub const NULL_CHECKSUM_U32: [u8; 4] = [0; 4];

-#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-#[error("data with size {0} larger than allowed {max} bytes", max = u8::MAX)]
-pub struct TlvLvDataTooLargeError(pub usize);
+pub struct TlvLvDataTooLarge(pub usize);

-/// First value: Found value. Second value: Expected value if there is one.
-#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
-#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-#[cfg_attr(feature = "defmt", derive(defmt::Format))]
-#[error("invalid TLV type field, found {found}, expected {expected:?}")]
-pub struct InvalidTlvTypeFieldError {
-    found: u8,
-    expected: Option<u8>,
+impl Display for TlvLvDataTooLarge {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        write!(
+            f,
+            "data with size {} larger than allowed {} bytes",
+            self.0,
+            u8::MAX
+        )
+    }
 }

-#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[cfg(feature = "std")]
+impl Error for TlvLvDataTooLarge {}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum TlvLvError {
-    #[error("{0}")]
-    DataTooLarge(#[from] TlvLvDataTooLargeError),
-    #[error("byte conversion error: {0}")]
-    ByteConversion(#[from] ByteConversionError),
-    #[error("{0}")]
-    InvalidTlvTypeField(#[from] InvalidTlvTypeFieldError),
-    #[error("invalid value length {0}")]
+    DataTooLarge(TlvLvDataTooLarge),
+    ByteConversion(ByteConversionError),
+    /// First value: Found value. Second value: Expected value if there is one.
+    InvalidTlvTypeField {
+        found: u8,
+        expected: Option<u8>,
+    },
+    /// Logically invalid value length detected. The value length may not exceed 255 bytes.
+    /// Depending on the concrete TLV type, the value length may also be logically invalid.
    InvalidValueLength(usize),
    /// Only applies to filestore requests and responses. Second name was missing where one is
    /// expected.
-    #[error("second name missing for filestore request or response")]
    SecondNameMissing,
    /// Invalid action code for filestore requests or responses.
-    #[error("invalid action code {0}")]
    InvalidFilestoreActionCode(u8),
 }

+impl From<TlvLvDataTooLarge> for TlvLvError {
+    fn from(value: TlvLvDataTooLarge) -> Self {
+        Self::DataTooLarge(value)
+    }
+}
+
+impl From<ByteConversionError> for TlvLvError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversion(value)
+    }
+}
+
+impl Display for TlvLvError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            TlvLvError::DataTooLarge(e) => {
+                write!(f, "{}", e)
+            }
+            TlvLvError::ByteConversion(e) => {
+                write!(f, "tlv or lv byte conversion: {}", e)
+            }
+            TlvLvError::InvalidTlvTypeField { found, expected } => {
+                write!(
+                    f,
+                    "invalid TLV type field, found {found}, expected {expected:?}"
+                )
+            }
+            TlvLvError::InvalidValueLength(len) => {
+                write!(f, "invalid value length {len}")
+            }
+            TlvLvError::SecondNameMissing => {
+                write!(f, "second name missing for filestore request or response")
+            }
+            TlvLvError::InvalidFilestoreActionCode(raw) => {
+                write!(f, "invalid filestore action code with raw value {raw}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for TlvLvError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            TlvLvError::DataTooLarge(e) => Some(e),
+            TlvLvError::ByteConversion(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
    use super::*;
--- a/src/cfdp/pdu/eof.rs
+++ b/src/cfdp/pdu/eof.rs
@ -297,7 +297,7 @@ mod tests {
        buf[written - 1] -= 1;
        let crc: u16 = ((buf[written - 2] as u16) << 8) as u16 | buf[written - 1] as u16;
        let error = EofPdu::from_bytes(&buf).unwrap_err();
-        if let PduError::Checksum(e) = error {
+        if let PduError::ChecksumError(e) = error {
            assert_eq!(e, crc);
        } else {
            panic!("expected crc error");
--- a/src/cfdp/pdu/file_data.rs
+++ b/src/cfdp/pdu/file_data.rs
@ -377,7 +377,7 @@ impl CfdpPdu for FileDataPduCreatorWithReservedDatafield<'_> {
    }
 }

-/// This structure is created with [FileDataPduCreatorWithReservedDatafield::write_to_bytes_partially]
+/// This structure is created with [FileDataPduCreatorReservedDatafield::write_to_bytes_partially]
 /// and provides an API to read file data from the virtual filesystem into the file data PDU buffer
 /// directly.
 ///
@ -544,7 +544,7 @@ mod tests {
        buf[written - 1] -= 1;
        let crc: u16 = ((buf[written - 2] as u16) << 8) | buf[written - 1] as u16;
        let error = FileDataPdu::from_bytes(&buf).unwrap_err();
-        if let PduError::Checksum(e) = error {
+        if let PduError::ChecksumError(e) = error {
            assert_eq!(e, crc);
        } else {
            panic!("expected crc error");
@ -753,7 +753,7 @@ mod tests {
        assert!(pdu_reader_error.is_err());
        let error = pdu_reader_error.unwrap_err();
        match error {
-            PduError::Checksum(_) => (),
+            PduError::ChecksumError(_) => (),
            _ => {
                panic!("unexpected PDU error {}", error)
            }
--- a/src/cfdp/pdu/finished.rs
+++ b/src/cfdp/pdu/finished.rs
@ -4,14 +4,14 @@ use crate::cfdp::pdu::{
 use crate::cfdp::tlv::{
    EntityIdTlv, FilestoreResponseTlv, GenericTlv, Tlv, TlvType, TlvTypeField, WritableTlv,
 };
-use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType};
+use crate::cfdp::{ConditionCode, CrcFlag, Direction, PduType, TlvLvError};
 use crate::ByteConversionError;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};

 use super::tlv::ReadableTlv;
-use super::{CfdpPdu, InvalidTlvTypeFieldError, WritablePduPacket};
+use super::{CfdpPdu, WritablePduPacket};

 #[derive(Debug, Copy, Clone, PartialEq, Eq, TryFromPrimitive, IntoPrimitive)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@ -332,26 +332,22 @@ impl<'buf> FinishedPduReader<'buf> {
                        // last TLV, everything else would break the whole handling of the packet
                        // TLVs.
                        if current_idx != full_len_without_crc {
-                            return Err(PduError::Format);
+                            return Err(PduError::FormatError);
                        }
                    } else {
-                        return Err(PduError::TlvLv(
-                            InvalidTlvTypeFieldError {
-                                found: tlv_type.into(),
-                                expected: Some(TlvType::FilestoreResponse.into()),
-                            }
-                            .into(),
-                        ));
+                        return Err(TlvLvError::InvalidTlvTypeField {
+                            found: tlv_type.into(),
+                            expected: Some(TlvType::FilestoreResponse.into()),
+                        }
+                        .into());
                    }
                }
                TlvTypeField::Custom(raw) => {
-                    return Err(PduError::TlvLv(
-                        InvalidTlvTypeFieldError {
-                            found: raw,
-                            expected: None,
-                        }
-                        .into(),
-                    ));
+                    return Err(TlvLvError::InvalidTlvTypeField {
+                        found: raw,
+                        expected: None,
+                    }
+                    .into());
                }
            }
        }
@ -568,7 +564,7 @@ mod tests {
        buf[written - 1] -= 1;
        let crc: u16 = ((buf[written - 2] as u16) << 8) as u16 | buf[written - 1] as u16;
        let error = FinishedPduReader::new(&buf).unwrap_err();
-        if let PduError::Checksum(e) = error {
+        if let PduError::ChecksumError(e) = error {
            assert_eq!(e, crc);
        } else {
            panic!("expected crc error");
--- a/src/cfdp/pdu/metadata.rs
+++ b/src/cfdp/pdu/metadata.rs
@ -720,7 +720,7 @@ pub mod tests {
    fn test_with_owned_opts() {
        let tlv1 = TlvOwned::new_empty(TlvType::FlowLabel);
        let msg_to_user: [u8; 4] = [1, 2, 3, 4];
-        let tlv2 = TlvOwned::new(TlvType::MsgToUser, &msg_to_user);
+        let tlv2 = TlvOwned::new(TlvType::MsgToUser, &msg_to_user).unwrap();
        let mut all_tlvs = tlv1.to_vec();
        all_tlvs.extend(tlv2.to_vec());
        let (src_filename, dest_filename, metadata_pdu) = generic_metadata_pdu(
@ -780,7 +780,7 @@ pub mod tests {
            assert_eq!(expected, Some(FileDirectiveType::MetadataPdu));
            assert_eq!(
                error.to_string(),
-                "invalid directive type, found 255, expected Some(MetadataPdu)"
+                "invalid directive type value 255, expected Some(MetadataPdu)"
            );
        } else {
            panic!("Expected InvalidDirectiveType error, got {:?}", error);
@ -806,7 +806,7 @@ pub mod tests {
            assert_eq!(expected, FileDirectiveType::MetadataPdu);
            assert_eq!(
                error.to_string(),
-                "wrong directive type, found EofPdu, expected MetadataPdu"
+                "found directive type EofPdu, expected MetadataPdu"
            );
        } else {
            panic!("Expected InvalidDirectiveType error, got {:?}", error);
--- a/src/cfdp/pdu/mod.rs
+++ b/src/cfdp/pdu/mod.rs
@ -1,10 +1,13 @@
 //! CFDP Packet Data Unit (PDU) support.
 use crate::cfdp::*;
-use crate::crc::CRC_CCITT_FALSE;
 use crate::util::{UnsignedByteField, UnsignedByteFieldU8, UnsignedEnum};
 use crate::ByteConversionError;
+use crate::CRC_CCITT_FALSE;
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
+use core::fmt::{Display, Formatter};
+#[cfg(feature = "std")]
+use std::error::Error;

 pub mod ack;
 pub mod eof;
@ -27,62 +30,137 @@ pub enum FileDirectiveType {
    KeepAlivePdu = 0x0c,
 }

-#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
-#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PduError {
-    #[error("byte conversion error: {0}")]
-    ByteConversion(#[from] ByteConversionError),
-    /// Found version ID invalid, not equal to [super::CFDP_VERSION_2].
-    #[error("CFDP version missmatch, found {0}, expected {ver}", ver = super::CFDP_VERSION_2)]
+    ByteConversion(ByteConversionError),
+    /// Found version ID invalid, not equal to [CFDP_VERSION_2].
    CfdpVersionMissmatch(u8),
    /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
-    #[error("invalid PDU entity ID length {0}, only [1, 2, 4, 8] are allowed")]
    InvalidEntityLen(u8),
    /// Invalid length for the entity ID detected. Only the values 1, 2, 4 and 8 are supported.
-    #[error("invalid transaction ID length {0}")]
    InvalidTransactionSeqNumLen(u8),
-    #[error(
-        "missmatch of PDU source ID length {src_id_len} and destination ID length {dest_id_len}"
-    )]
    SourceDestIdLenMissmatch {
        src_id_len: usize,
        dest_id_len: usize,
    },
    /// Wrong directive type, for example when parsing the directive field for a file directive
    /// PDU.
-    #[error("wrong directive type, found {found:?}, expected {expected:?}")]
    WrongDirectiveType {
        found: FileDirectiveType,
        expected: FileDirectiveType,
    },
    /// The directive type field contained a value not in the range of permitted values. This can
    /// also happen if an invalid value is passed to the ACK PDU constructor.
-    #[error("invalid directive type, found {found:?}, expected {expected:?}")]
    InvalidDirectiveType {
        found: u8,
        expected: Option<FileDirectiveType>,
    },
-    #[error("invalid start or end of scope value for NAK PDU")]
    InvalidStartOrEndOfScopeValue,
    /// Invalid condition code. Contains the raw detected value.
-    #[error("invalid condition code {0}")]
    InvalidConditionCode(u8),
    /// Invalid checksum type which is not part of the checksums listed in the
    /// [SANA Checksum Types registry](https://sanaregistry.org/r/checksum_identifiers/).
-    #[error("invalid checksum type {0}")]
    InvalidChecksumType(u8),
-    #[error("file size {0} too large")]
    FileSizeTooLarge(u64),
    /// If the CRC flag for a PDU is enabled and the checksum check fails. Contains raw 16-bit CRC.
-    #[error("checksum error for checksum {0}")]
-    Checksum(u16),
+    ChecksumError(u16),
    /// Generic error for invalid PDU formats.
-    #[error("generic PDU format error")]
-    Format,
+    FormatError,
    /// Error handling a TLV field.
-    #[error("PDU error: {0}")]
-    TlvLv(#[from] TlvLvError),
+    TlvLvError(TlvLvError),
+}
+
+impl Display for PduError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            PduError::InvalidEntityLen(raw_id) => {
+                write!(
+                    f,
+                    "invalid PDU entity ID length {raw_id}, only [1, 2, 4, 8] are allowed"
+                )
+            }
+            PduError::InvalidStartOrEndOfScopeValue => {
+                write!(f, "invalid start or end of scope for NAK PDU")
+            }
+            PduError::InvalidTransactionSeqNumLen(raw_id) => {
+                write!(
+                    f,
+                    "invalid PDUtransaction seq num length {raw_id}, only [1, 2, 4, 8] are allowed"
+                )
+            }
+            PduError::CfdpVersionMissmatch(raw) => {
+                write!(
+                    f,
+                    "cfdp version missmatch, found {raw}, expected {CFDP_VERSION_2}"
+                )
+            }
+            PduError::SourceDestIdLenMissmatch {
+                src_id_len,
+                dest_id_len,
+            } => {
+                write!(
+                    f,
+                    "missmatch of PDU source length {src_id_len} and destination length {dest_id_len}"
+                )
+            }
+            PduError::ByteConversion(e) => {
+                write!(f, "{}", e)
+            }
+            PduError::FileSizeTooLarge(value) => {
+                write!(f, "file size value {value} exceeds allowed 32 bit width")
+            }
+            PduError::WrongDirectiveType { found, expected } => {
+                write!(f, "found directive type {found:?}, expected {expected:?}")
+            }
+            PduError::InvalidConditionCode(raw_code) => {
+                write!(f, "found invalid condition code with raw value {raw_code}")
+            }
+            PduError::InvalidDirectiveType { found, expected } => {
+                write!(
+                    f,
+                    "invalid directive type value {found}, expected {expected:?}"
+                )
+            }
+            PduError::InvalidChecksumType(checksum_type) => {
+                write!(f, "invalid checksum type {checksum_type}")
+            }
+            PduError::ChecksumError(checksum) => {
+                write!(f, "checksum error for CRC {checksum:#04x}")
+            }
+            PduError::TlvLvError(error) => {
+                write!(f, "pdu tlv error: {error}")
+            }
+            PduError::FormatError => {
+                write!(f, "generic PDU format error")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for PduError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            PduError::ByteConversion(e) => Some(e),
+            PduError::TlvLvError(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl From<ByteConversionError> for PduError {
+    #[inline]
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversion(value)
+    }
+}
+
+impl From<TlvLvError> for PduError {
+    #[inline]
+    fn from(e: TlvLvError) -> Self {
+        Self::TlvLvError(e)
+    }
 }

 pub trait WritablePduPacket {
@ -454,7 +532,7 @@ impl PduHeader {
            let mut digest = CRC_CCITT_FALSE.digest();
            digest.update(&buf[..self.pdu_len()]);
            if digest.finalize() != 0 {
-                return Err(PduError::Checksum(u16::from_be_bytes(
+                return Err(PduError::ChecksumError(u16::from_be_bytes(
                    buf[self.pdu_len() - 2..self.pdu_len()].try_into().unwrap(),
                )));
            }
@ -903,7 +981,7 @@ mod tests {
            assert_eq!(raw_version, CFDP_VERSION_2 + 1);
            assert_eq!(
                error.to_string(),
-                "CFDP version missmatch, found 2, expected 1"
+                "cfdp version missmatch, found 2, expected 1"
            );
        } else {
            panic!("invalid exception: {}", error);
@ -951,7 +1029,7 @@ mod tests {
            assert_eq!(expected, 7);
            assert_eq!(
                error.to_string(),
-                "byte conversion error: source slice with size 6 too small, expected at least 7 bytes"
+                "source slice with size 6 too small, expected at least 7 bytes"
            );
        }
    }
@ -1006,7 +1084,7 @@ mod tests {
            assert_eq!(dest_id_len, 2);
            assert_eq!(
                error.to_string(),
-                "missmatch of PDU source ID length 1 and destination ID length 2"
+                "missmatch of PDU source length 1 and destination length 2"
            );
        }
    }
--- a/src/cfdp/pdu/nak.rs
+++ b/src/cfdp/pdu/nak.rs
@ -61,7 +61,7 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
        start_of_scope: u32,
        end_of_scope: u32,
        segment_requests: &'seg_reqs [(u32, u32)],
-    ) -> Result<NakPduCreator<'seg_reqs>, PduError> {
+    ) -> Result<NakPduCreator, PduError> {
        let mut passed_segment_requests = None;
        if !segment_requests.is_empty() {
            passed_segment_requests = Some(SegmentRequests::U32Pairs(segment_requests));
@ -79,7 +79,7 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
        start_of_scope: u64,
        end_of_scope: u64,
        segment_requests: &'seg_reqs [(u64, u64)],
-    ) -> Result<NakPduCreator<'seg_reqs>, PduError> {
+    ) -> Result<NakPduCreator, PduError> {
        let mut passed_segment_requests = None;
        if !segment_requests.is_empty() {
            passed_segment_requests = Some(SegmentRequests::U64Pairs(segment_requests));
@ -97,7 +97,7 @@ impl<'seg_reqs> NakPduCreator<'seg_reqs> {
        start_of_scope: u64,
        end_of_scope: u64,
        segment_requests: Option<SegmentRequests<'seg_reqs>>,
-    ) -> Result<NakPduCreator<'seg_reqs>, PduError> {
+    ) -> Result<NakPduCreator, PduError> {
        // Force correct direction flag.
        pdu_header.pdu_conf.direction = Direction::TowardsSender;
        if let Some(ref segment_requests) = segment_requests {
@ -269,7 +269,7 @@ impl SegReqFromBytes for u64 {
    }
 }

-impl<T> Iterator for SegmentRequestIter<'_, T>
+impl<'a, T> Iterator for SegmentRequestIter<'a, T>
 where
    T: SegReqFromBytes,
 {
@ -282,8 +282,8 @@ where
    }
 }

-impl<'a> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'_, u32> {
-    fn eq(&self, other: &SegmentRequests<'a>) -> bool {
+impl<'a, 'b> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'b, u32> {
+    fn eq(&self, other: &SegmentRequests) -> bool {
        match other {
            SegmentRequests::U32Pairs(pairs) => self.compare_pairs(pairs),
            SegmentRequests::U64Pairs(pairs) => {
@ -296,8 +296,8 @@ impl<'a> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'_, u32> {
    }
 }

-impl<'a> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'_, u64> {
-    fn eq(&self, other: &SegmentRequests<'a>) -> bool {
+impl<'a, 'b> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'b, u64> {
+    fn eq(&self, other: &SegmentRequests) -> bool {
        match other {
            SegmentRequests::U32Pairs(pairs) => {
                if pairs.is_empty() && self.seq_req_raw.is_empty() {
@ -310,7 +310,7 @@ impl<'a> PartialEq<SegmentRequests<'a>> for SegmentRequestIter<'_, u64> {
    }
 }

-impl<T> SegmentRequestIter<'_, T>
+impl<'a, T> SegmentRequestIter<'a, T>
 where
    T: SegReqFromBytes + PartialEq,
 {
@ -374,11 +374,11 @@ impl CfdpPdu for NakPduReader<'_> {
 }

 impl<'seg_reqs> NakPduReader<'seg_reqs> {
-    pub fn new(buf: &'seg_reqs [u8]) -> Result<NakPduReader<'seg_reqs>, PduError> {
+    pub fn new(buf: &'seg_reqs [u8]) -> Result<NakPduReader, PduError> {
        Self::from_bytes(buf)
    }

-    pub fn from_bytes(buf: &'seg_reqs [u8]) -> Result<NakPduReader<'seg_reqs>, PduError> {
+    pub fn from_bytes(buf: &'seg_reqs [u8]) -> Result<NakPduReader, PduError> {
        let (pdu_header, mut current_idx) = PduHeader::from_bytes(buf)?;
        let full_len_without_crc = pdu_header.verify_length_and_checksum(buf)?;
        // Minimum length of 9: 1 byte directive field and start and end of scope for normal file
@ -474,7 +474,7 @@ impl<'seg_reqs> NakPduReader<'seg_reqs> {
    }
 }

-impl<'a> PartialEq<NakPduCreator<'a>> for NakPduReader<'_> {
+impl<'a, 'b> PartialEq<NakPduCreator<'a>> for NakPduReader<'b> {
    fn eq(&self, other: &NakPduCreator<'a>) -> bool {
        if self.pdu_header() != other.pdu_header()
            || self.end_of_scope() != other.end_of_scope()
@ -751,7 +751,7 @@ mod tests {
        if let PduError::InvalidStartOrEndOfScopeValue = error {
            assert_eq!(
                error.to_string(),
-                "invalid start or end of scope value for NAK PDU"
+                "invalid start or end of scope for NAK PDU"
            );
        } else {
            panic!("unexpected error {error}");
@ -796,7 +796,7 @@ mod tests {
        nak_vec[nak_pdu.len_written() - 1] -= 1;
        let nak_pdu_deser = NakPduReader::new(&nak_vec);
        assert!(nak_pdu_deser.is_err());
-        if let Err(PduError::Checksum(raw)) = nak_pdu_deser {
+        if let Err(PduError::ChecksumError(raw)) = nak_pdu_deser {
            assert_eq!(
                raw,
                u16::from_be_bytes(nak_vec[nak_pdu.len_written() - 2..].try_into().unwrap())
--- a/src/cfdp/tlv/mod.rs
+++ b/src/cfdp/tlv/mod.rs
@ -15,7 +15,7 @@ use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};

-use super::{InvalidTlvTypeFieldError, TlvLvDataTooLargeError};
+use super::TlvLvDataTooLarge;

 pub mod msg_to_user;

@ -153,14 +153,14 @@ pub struct Tlv<'data> {
 }

 impl<'data> Tlv<'data> {
-    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvDataTooLargeError> {
+    pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Tlv, TlvLvDataTooLarge> {
        Ok(Tlv {
            tlv_type_field: TlvTypeField::Standard(tlv_type),
            lv: Lv::new(data)?,
        })
    }

-    pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Result<Tlv, TlvLvDataTooLargeError> {
+    pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Result<Tlv, TlvLvDataTooLarge> {
        Ok(Tlv {
            tlv_type_field: TlvTypeField::Custom(tlv_type),
            lv: Lv::new(data)?,
@ -179,7 +179,7 @@ impl<'data> Tlv<'data> {
    /// bytestream with the exact size of the expected TLV. This function will take care
    /// of parsing the length byte, and the length of the parsed TLV can be retrieved using
    /// [Self::len_full].
-    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, ByteConversionError> {
+    pub fn from_bytes(buf: &'data [u8]) -> Result<Tlv<'data>, TlvLvError> {
        generic_len_check_deserialization(buf, MIN_TLV_LEN)?;
        let mut tlv = Self {
            tlv_type_field: TlvTypeField::from(buf[0]),
@ -239,6 +239,8 @@ impl GenericTlv for Tlv<'_> {

 #[cfg(feature = "alloc")]
 pub mod alloc_mod {
+    use crate::cfdp::TlvLvDataTooLarge;
+
    use super::*;

    /// Owned variant of [Tlv] which is consequently [Clone]able and does not have a lifetime
@ -252,18 +254,24 @@ pub mod alloc_mod {
    }

    impl TlvOwned {
-        pub fn new(tlv_type: TlvType, data: &[u8]) -> Self {
-            Self {
+        pub fn new(tlv_type: TlvType, data: &[u8]) -> Result<Self, TlvLvDataTooLarge> {
+            if data.len() > u8::MAX as usize {
+                return Err(TlvLvDataTooLarge(data.len()));
+            }
+            Ok(Self {
                tlv_type_field: TlvTypeField::Standard(tlv_type),
                data: data.to_vec(),
-            }
+            })
        }

-        pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Self {
-            Self {
+        pub fn new_with_custom_type(tlv_type: u8, data: &[u8]) -> Result<Self, TlvLvDataTooLarge> {
+            if data.len() > u8::MAX as usize {
+                return Err(TlvLvDataTooLarge(data.len()));
+            }
+            Ok(Self {
                tlv_type_field: TlvTypeField::Custom(tlv_type),
                data: data.to_vec(),
-            }
+            })
        }

        /// Creates a TLV with an empty value field.
@ -335,7 +343,7 @@ impl EntityIdTlv {
        Self { entity_id }
    }

-    fn len_check(buf: &[u8]) -> Result<(), ByteConversionError> {
+    fn check_min_len(buf: &[u8]) -> Result<(), ByteConversionError> {
        if buf.len() < 2 {
            return Err(ByteConversionError::ToSliceTooSmall {
                found: buf.len(),
@ -358,7 +366,7 @@ impl EntityIdTlv {
    }

    pub fn from_bytes(buf: &[u8]) -> Result<Self, TlvLvError> {
-        Self::len_check(buf)?;
+        Self::check_min_len(buf)?;
        verify_tlv_type(buf[0], TlvType::EntityId)?;
        let len = buf[1];
        if len != 1 && len != 2 && len != 4 && len != 8 {
@ -369,19 +377,31 @@ impl EntityIdTlv {
        Ok(Self { entity_id })
    }

-    /// Convert to a generic [Tlv], which also erases the programmatic type information.
+    /// Convert to a generic [Tlv], which also erases the type information.
    pub fn to_tlv(self, buf: &mut [u8]) -> Result<Tlv, ByteConversionError> {
-        Self::len_check(buf)?;
+        Self::check_min_len(buf)?;
        self.entity_id
            .write_to_be_bytes(&mut buf[2..2 + self.entity_id.size()])?;
-        // Can't fail.
+        if buf.len() < self.len_value() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_value(),
+            });
+        }
+        // We performed all checks necessary to ensure this call never panics.
        Ok(Tlv::new(TlvType::EntityId, &buf[2..2 + self.entity_id.size()]).unwrap())
    }
+
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        // Unwrap is okay here, entity ID should never be larger than maximum allowed size.
+        TlvOwned::new(TlvType::EntityId, &self.entity_id.to_vec()).unwrap()
+    }
 }

 impl WritableTlv for EntityIdTlv {
    fn write_to_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
-        Self::len_check(buf)?;
+        Self::check_min_len(buf)?;
        buf[0] = TlvType::EntityId as u8;
        buf[1] = self.entity_id.size() as u8;
        Ok(2 + self.entity_id.write_to_be_bytes(&mut buf[2..])?)
@ -398,26 +418,24 @@ impl GenericTlv for EntityIdTlv {
    }
 }

-impl TryFrom<Tlv<'_>> for EntityIdTlv {
+impl<'data> TryFrom<Tlv<'data>> for EntityIdTlv {
    type Error = TlvLvError;

-    fn try_from(value: Tlv) -> Result<Self, TlvLvError> {
+    fn try_from(value: Tlv) -> Result<Self, Self::Error> {
        match value.tlv_type_field {
            TlvTypeField::Standard(tlv_type) => {
                if tlv_type != TlvType::EntityId {
-                    return Err(InvalidTlvTypeFieldError {
+                    return Err(TlvLvError::InvalidTlvTypeField {
                        found: tlv_type as u8,
                        expected: Some(TlvType::EntityId as u8),
-                    }
-                    .into());
+                    });
                }
            }
            TlvTypeField::Custom(val) => {
-                return Err(InvalidTlvTypeFieldError {
+                return Err(TlvLvError::InvalidTlvTypeField {
                    found: val,
                    expected: Some(TlvType::EntityId as u8),
-                }
-                .into());
+                });
            }
        }
        let len_value = value.value().len();
@ -622,6 +640,12 @@ impl<'first_name, 'second_name> FilestoreRequestTlv<'first_name, 'second_name> {
            },
        })
    }
+
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        // The API should ensure the data field is never too large, so unwrapping here is okay.
+        TlvOwned::new(TlvType::FilestoreRequest, &self.to_vec()[2..]).unwrap()
+    }
 }

 impl WritableTlv for FilestoreRequestTlv<'_, '_> {
@ -807,6 +831,12 @@ impl<'first_name, 'second_name, 'fs_msg> FilestoreResponseTlv<'first_name, 'seco
            filestore_message,
        })
    }
+
+    #[cfg(feature = "alloc")]
+    pub fn to_owned(&self) -> TlvOwned {
+        // The API should ensure the data field is never too large, so unwrap is okay here.
+        TlvOwned::new(TlvType::FilestoreResponse, &self.to_vec()[2..]).unwrap()
+    }
 }

 impl WritableTlv for FilestoreResponseTlv<'_, '_, '_> {
@ -848,16 +878,13 @@ impl GenericTlv for FilestoreResponseTlv<'_, '_, '_> {
    }
 }

-pub(crate) fn verify_tlv_type(
-    raw_type: u8,
-    expected_tlv_type: TlvType,
-) -> Result<(), InvalidTlvTypeFieldError> {
-    let tlv_type = TlvType::try_from(raw_type).map_err(|_| InvalidTlvTypeFieldError {
+pub(crate) fn verify_tlv_type(raw_type: u8, expected_tlv_type: TlvType) -> Result<(), TlvLvError> {
+    let tlv_type = TlvType::try_from(raw_type).map_err(|_| TlvLvError::InvalidTlvTypeField {
        found: raw_type,
        expected: Some(expected_tlv_type.into()),
    })?;
    if tlv_type != expected_tlv_type {
-        return Err(InvalidTlvTypeFieldError {
+        return Err(TlvLvError::InvalidTlvTypeField {
            found: tlv_type as u8,
            expected: Some(expected_tlv_type as u8),
        });
@ -1052,15 +1079,11 @@ mod tests {
        let tlv_res = Tlv::new(TlvType::MsgToUser, &buf_too_large);
        assert!(tlv_res.is_err());
        let error = tlv_res.unwrap_err();
-        match error {
-            TlvLvDataTooLargeError(size) => {
-                assert_eq!(size, u8::MAX as usize + 1);
-                assert_eq!(
-                    error.to_string(),
-                    "data with size 256 larger than allowed 255 bytes"
-                );
-            }
-        }
+        assert_eq!(error.0, u8::MAX as usize + 1);
+        assert_eq!(
+            error.to_string(),
+            "data with size 256 larger than allowed 255 bytes"
+        );
    }

    #[test]
@ -1369,8 +1392,7 @@ mod tests {
        let error = EntityIdTlv::try_from(msg_to_user_tlv);
        assert!(error.is_err());
        let error = error.unwrap_err();
-        if let TlvLvError::InvalidTlvTypeField(InvalidTlvTypeFieldError { found, expected }) = error
-        {
+        if let TlvLvError::InvalidTlvTypeField { found, expected } = error {
            assert_eq!(found, TlvType::MsgToUser as u8);
            assert_eq!(expected, Some(TlvType::EntityId as u8));
            assert_eq!(
@ -1435,7 +1457,7 @@ mod tests {
        let entity_id = UbfU8::new(5);
        let mut buf: [u8; 4] = [0; 4];
        assert!(entity_id.write_to_be_bytes(&mut buf).is_ok());
-        let tlv_res = TlvOwned::new(TlvType::EntityId, &buf[0..1]);
+        let tlv_res = TlvOwned::new(TlvType::EntityId, &buf[0..1]).expect("creating TLV failed");
        assert_eq!(
            tlv_res.tlv_type_field(),
            TlvTypeField::Standard(TlvType::EntityId)
@ -1462,7 +1484,7 @@ mod tests {

    #[test]
    fn test_owned_tlv_custom_type() {
-        let tlv_res = TlvOwned::new_with_custom_type(32, &[]);
+        let tlv_res = TlvOwned::new_with_custom_type(32, &[]).unwrap();
        assert_eq!(tlv_res.tlv_type_field(), TlvTypeField::Custom(32));
        assert_eq!(tlv_res.len_full(), 2);
        assert_eq!(tlv_res.value().len(), 0);
--- a/src/cfdp/tlv/msg_to_user.rs
+++ b/src/cfdp/tlv/msg_to_user.rs
@ -2,10 +2,7 @@
 #[cfg(feature = "alloc")]
 use super::TlvOwned;
 use super::{GenericTlv, ReadableTlv, Tlv, TlvLvError, TlvType, TlvTypeField, WritableTlv};
-use crate::{
-    cfdp::{InvalidTlvTypeFieldError, TlvLvDataTooLargeError},
-    ByteConversionError,
-};
+use crate::{cfdp::TlvLvDataTooLarge, ByteConversionError};
 use delegate::delegate;

 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
@ -15,7 +12,7 @@ pub struct MsgToUserTlv<'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>, TlvLvDataTooLargeError> {
+    pub fn new(value: &'data [u8]) -> Result<MsgToUserTlv<'data>, TlvLvDataTooLarge> {
        Ok(Self {
            tlv: Tlv::new(TlvType::MsgToUser, value)?,
        })
@ -65,19 +62,17 @@ impl<'data> MsgToUserTlv<'data> {
        match msg_to_user.tlv.tlv_type_field() {
            TlvTypeField::Standard(tlv_type) => {
                if tlv_type != TlvType::MsgToUser {
-                    return Err(InvalidTlvTypeFieldError {
+                    return Err(TlvLvError::InvalidTlvTypeField {
                        found: tlv_type as u8,
                        expected: Some(TlvType::MsgToUser as u8),
-                    }
-                    .into());
+                    });
                }
            }
            TlvTypeField::Custom(raw) => {
-                return Err(InvalidTlvTypeFieldError {
+                return Err(TlvLvError::InvalidTlvTypeField {
                    found: raw,
                    expected: Some(TlvType::MsgToUser as u8),
-                }
-                .into());
+                });
            }
        }
        Ok(msg_to_user)
@ -210,9 +205,9 @@ mod tests {
    fn test_reserved_msg_deserialization_invalid_type() {
        let trash: [u8; 5] = [TlvType::FlowLabel as u8, 3, 1, 2, 3];
        let error = MsgToUserTlv::from_bytes(&trash).unwrap_err();
-        if let TlvLvError::InvalidTlvTypeField(inner) = error {
-            assert_eq!(inner.found, TlvType::FlowLabel as u8);
-            assert_eq!(inner.expected, Some(TlvType::MsgToUser as u8));
+        if let TlvLvError::InvalidTlvTypeField { found, expected } = error {
+            assert_eq!(found, TlvType::FlowLabel as u8);
+            assert_eq!(expected, Some(TlvType::MsgToUser as u8));
        } else {
            panic!("Wrong error type returned: {:?}", error);
        }
--- a/src/crc.rs
+++ b/src/crc.rs
@ -1,11 +0,0 @@
-/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
-/// a [crc::NoTable] as the CRC implementation.
-pub const CRC_CCITT_FALSE_NO_TABLE: crc::Crc<u16, crc::NoTable> =
-    crc::Crc::<u16, crc::NoTable>::new(&crc::CRC_16_IBM_3740);
-/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
-/// [crc::Table<1>] as the CRC implementation.
-pub const CRC_CCITT_FALSE: crc::Crc<u16> = crc::Crc::<u16>::new(&crc::CRC_16_IBM_3740);
-/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard, using
-/// a [crc::Table<16>] large table as the CRC implementation.
-pub const CRC_CCITT_FALSE_BIG_TABLE: crc::Crc<u16, crc::Table<16>> =
-    crc::Crc::<u16, crc::Table<16>>::new(&crc::CRC_16_IBM_3740);
--- a/src/ecss/mod.rs
+++ b/src/ecss/mod.rs
@ -3,17 +3,16 @@
 //!
 //! You can find the PUS telecommand types in the [tc] module and the the PUS telemetry
 //! types inside the [tm] module.
-use crate::{
-    crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE},
-    ByteConversionError, CcsdsPacket,
-};
+use crate::{ByteConversionError, CcsdsPacket, CRC_CCITT_FALSE};
 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
-use core::fmt::Debug;
+use core::fmt::{Debug, Display, Formatter};
 use core::mem::size_of;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
+#[cfg(feature = "std")]
+use std::error::Error;

 pub mod event;
 pub mod hk;
@ -149,19 +148,50 @@ pub enum PfcReal {
    DoubleMilStd = 4,
 }

-#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum PusError {
-    #[error("PUS version {0:?} not supported")]
    VersionNotSupported(PusVersion),
-    #[error("checksum verification for crc16 {0:#06x} failed")]
    ChecksumFailure(u16),
    /// CRC16 needs to be calculated first
-    //#[error("crc16 was not calculated")]
-    //CrcCalculationMissing,
-    #[error("pus error: {0}")]
-    ByteConversion(#[from] ByteConversionError),
+    CrcCalculationMissing,
+    ByteConversion(ByteConversionError),
+}
+
+impl Display for PusError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            PusError::VersionNotSupported(v) => {
+                write!(f, "PUS version {v:?} not supported")
+            }
+            PusError::ChecksumFailure(crc) => {
+                write!(f, "checksum verification for crc16 {crc:#06x} failed")
+            }
+            PusError::CrcCalculationMissing => {
+                write!(f, "crc16 was not calculated")
+            }
+            PusError::ByteConversion(e) => {
+                write!(f, "pus error: {e}")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for PusError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        if let PusError::ByteConversion(e) = self {
+            return Some(e);
+        }
+        None
+    }
+}
+
+impl From<ByteConversionError> for PusError {
+    fn from(e: ByteConversionError) -> Self {
+        PusError::ByteConversion(e)
+    }
 }

 /// Generic trait to describe common attributes for both PUS Telecommands (TC) and PUS Telemetry
@ -173,7 +203,7 @@ pub trait PusPacket: CcsdsPacket {
    fn service(&self) -> u8;
    fn subservice(&self) -> u8;
    fn user_data(&self) -> &[u8];
-    fn opt_crc16(&self) -> Option<u16>;
+    fn crc16(&self) -> Option<u16>;
 }

 pub(crate) fn crc_from_raw_data(raw_data: &[u8]) -> Result<u16, ByteConversionError> {
@ -210,7 +240,7 @@ pub(crate) fn user_data_from_raw(
    }
 }

-pub fn verify_crc16_ccitt_false_from_raw_to_pus_error(
+pub(crate) fn verify_crc16_ccitt_false_from_raw_to_pus_error(
    raw_data: &[u8],
    crc16: u16,
 ) -> Result<(), PusError> {
@ -219,15 +249,6 @@ pub fn verify_crc16_ccitt_false_from_raw_to_pus_error(
        .ok_or(PusError::ChecksumFailure(crc16))
 }

-pub fn verify_crc16_ccitt_false_from_raw_to_pus_error_no_table(
-    raw_data: &[u8],
-    crc16: u16,
-) -> Result<(), PusError> {
-    verify_crc16_ccitt_false_from_raw_no_table(raw_data)
-        .then_some(())
-        .ok_or(PusError::ChecksumFailure(crc16))
-}
-
 pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
    let mut digest = CRC_CCITT_FALSE.digest();
    digest.update(raw_data);
@ -237,15 +258,6 @@ pub(crate) fn verify_crc16_ccitt_false_from_raw(raw_data: &[u8]) -> bool {
    false
 }

-pub(crate) fn verify_crc16_ccitt_false_from_raw_no_table(raw_data: &[u8]) -> bool {
-    let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
-    digest.update(raw_data);
-    if digest.finalize() == 0 {
-        return true;
-    }
-    false
-}
-
 macro_rules! ccsds_impl {
    () => {
        delegate!(to self.sp_header {
@ -370,34 +382,7 @@ generic_ecss_enum_typedefs_and_from_impls! {
 /// on the serialization of those packets.
 pub trait WritablePusPacket {
    fn len_written(&self) -> usize;
-
-    /// Writes the packet to the given slice without writing the CRC.
-    ///
-    /// The returned size is the written size WITHOUT the CRC.
-    fn write_to_bytes_no_crc(&self, slice: &mut [u8]) -> Result<usize, PusError>;
-
-    /// First uses [Self::write_to_bytes_no_crc] to write the packet to the given slice and then
-    /// uses the [CRC_CCITT_FALSE] to calculate the CRC and write it to the slice.
-    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = self.write_to_bytes_no_crc(slice)?;
-        let mut digest = CRC_CCITT_FALSE.digest();
-        digest.update(&slice[0..curr_idx]);
-        slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
-    /// First uses [Self::write_to_bytes_no_crc] to write the packet to the given slice and then
-    /// uses the [CRC_CCITT_FALSE_NO_TABLE] to calculate the CRC and write it to the slice.
-    fn write_to_bytes_crc_no_table(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        let mut curr_idx = self.write_to_bytes_no_crc(slice)?;
-        let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
-        digest.update(&slice[0..curr_idx]);
-        slice[curr_idx..curr_idx + 2].copy_from_slice(&digest.finalize().to_be_bytes());
-        curr_idx += 2;
-        Ok(curr_idx)
-    }
-
+    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError>;
    #[cfg(feature = "alloc")]
    fn to_vec(&self) -> Result<Vec<u8>, PusError> {
        // This is the correct way to do this. See
--- a/src/ecss/tc.rs
+++ b/src/ecss/tc.rs
@ -33,26 +33,23 @@
 //! assert_eq!(pus_tc.subservice(), 1);
 //! assert_eq!(pus_tc.apid(), 0x02);
 //! ```
-use crate::crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE};
 use crate::ecss::{
    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,
    WritablePusPacket,
 };
-use crate::SpHeader;
 use crate::{ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, CCSDS_HEADER_LEN};
+use crate::{SpHeader, CRC_CCITT_FALSE};
 use core::mem::size_of;
 use delegate::delegate;
 use num_enum::{IntoPrimitive, TryFromPrimitive};
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-use zerocopy::{FromBytes, IntoBytes};
+use zerocopy::AsBytes;

 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;

-use super::verify_crc16_ccitt_false_from_raw_to_pus_error_no_table;
-
 /// PUS C secondary header length is fixed
 pub const PUC_TC_SECONDARY_HEADER_LEN: usize = size_of::<zc::PusTcSecondaryHeader>();
 pub const PUS_TC_MIN_LEN_WITHOUT_APP_DATA: usize =
@ -89,9 +86,9 @@ pub trait GenericPusTcSecondaryHeader {
 pub mod zc {
    use crate::ecss::tc::GenericPusTcSecondaryHeader;
    use crate::ecss::{PusError, PusVersion};
-    use zerocopy::{FromBytes, Immutable, IntoBytes, NetworkEndian, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, NetworkEndian, Unaligned, U16};

-    #[derive(FromBytes, IntoBytes, Immutable, Unaligned)]
+    #[derive(FromZeroes, FromBytes, AsBytes, Unaligned)]
    #[repr(C)]
    pub struct PusTcSecondaryHeader {
        version_ack: u8,
@ -118,7 +115,7 @@ pub mod zc {
    impl GenericPusTcSecondaryHeader for PusTcSecondaryHeader {
        #[inline]
        fn pus_version(&self) -> PusVersion {
-            PusVersion::try_from((self.version_ack >> 4) & 0b1111).unwrap_or(PusVersion::Invalid)
+            PusVersion::try_from(self.version_ack >> 4 & 0b1111).unwrap_or(PusVersion::Invalid)
        }

        #[inline]
@ -141,6 +138,16 @@ pub mod zc {
            self.source_id.get()
        }
    }
+
+    impl PusTcSecondaryHeader {
+        pub fn write_to_bytes(&self, slice: &mut [u8]) -> Option<()> {
+            self.write_to(slice)
+        }
+
+        pub fn from_bytes(slice: &[u8]) -> Option<Self> {
+            Self::read_from(slice)
+        }
+    }
 }

 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
@ -242,13 +249,13 @@ impl<'app_data> PusTcCreator<'app_data> {
    /// # Arguments
    ///
    /// * `sp_header` - Space packet header information. The correct packet type and the secondary
-    ///   header flag are set correctly by the constructor.
+    ///     header flag are set correctly by the constructor.
    /// * `sec_header` - Information contained in the data field header, including the service
-    ///   and subservice type
+    ///     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, [Self::update_ccsds_data_len] can be called to set
-    ///   the correct value to this field manually
+    ///     field. If this is not set to true, [Self::update_ccsds_data_len] can be called to set
+    ///     the correct value to this field manually
    #[inline]
    pub fn new(
        mut sp_header: SpHeader,
@ -345,17 +352,6 @@ impl<'app_data> PusTcCreator<'app_data> {
        digest.finalize()
    }

-    /// This function calculates and returns the CRC16 for the current packet.
-    pub fn calc_own_crc16_no_table(&self) -> u16 {
-        let mut digest = CRC_CCITT_FALSE_NO_TABLE.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());
-        digest.update(self.app_data);
-        digest.finalize()
-    }
-
    #[cfg(feature = "alloc")]
    pub fn append_to_vec(&self, vec: &mut Vec<u8>) -> usize {
        let sph_zc = crate::zc::SpHeader::from(self.sp_header);
@ -372,49 +368,6 @@ impl<'app_data> PusTcCreator<'app_data> {
        vec.extend_from_slice(&digest.finalize().to_be_bytes());
        appended_len
    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, ByteConversionError> {
-        let writer_unfinalized = self.common_write(slice)?;
-        Ok(writer_unfinalized.finalize())
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes_crc_no_table(
-        &self,
-        slice: &mut [u8],
-    ) -> Result<usize, ByteConversionError> {
-        let writer_unfinalized = self.common_write(slice)?;
-        Ok(writer_unfinalized.finalize_crc_no_table())
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes_no_crc(&self, slice: &mut [u8]) -> Result<usize, ByteConversionError> {
-        let writer_unfinalized = self.common_write(slice)?;
-        Ok(writer_unfinalized.finalize_no_crc())
-    }
-
-    fn common_write<'a>(
-        &self,
-        slice: &'a mut [u8],
-    ) -> Result<PusTcCreatorWithReservedAppData<'a>, ByteConversionError> {
-        if self.len_written() > slice.len() {
-            return Err(ByteConversionError::ToSliceTooSmall {
-                found: slice.len(),
-                expected: self.len_written(),
-            });
-        }
-        let mut writer_unfinalized = PusTcCreatorWithReservedAppData::write_to_bytes_partially(
-            slice,
-            self.sp_header,
-            self.sec_header,
-            self.app_data.len(),
-        )?;
-        writer_unfinalized
-            .app_data_mut()
-            .copy_from_slice(self.app_data);
-        Ok(writer_unfinalized)
-    }
 }

 impl WritablePusPacket for PusTcCreator<'_> {
@ -424,16 +377,32 @@ impl WritablePusPacket for PusTcCreator<'_> {
    }

    /// Write the raw PUS byte representation to a provided buffer.
-    fn write_to_bytes_no_crc(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        Ok(Self::write_to_bytes_no_crc(self, slice)?)
-    }
-
    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        Ok(Self::write_to_bytes(self, slice)?)
-    }
+        let mut curr_idx = 0;
+        let tc_header_len = size_of::<zc::PusTcSecondaryHeader>();
+        let total_size = self.len_written();
+        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)?;

-    fn write_to_bytes_crc_no_table(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        Ok(Self::write_to_bytes_crc_no_table(self, slice)?)
+        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)
    }
 }

@ -457,7 +426,7 @@ impl PusPacket for PusTcCreator<'_> {
    }

    #[inline]
-    fn opt_crc16(&self) -> Option<u16> {
+    fn crc16(&self) -> Option<u16> {
        Some(self.calc_own_crc16())
    }
 }
@ -479,133 +448,6 @@ impl GenericPusTcSecondaryHeader for PusTcCreator<'_> {

 impl IsPusTelecommand for PusTcCreator<'_> {}

-/// A specialized variant of [PusTcCreator] designed for efficiency when handling large source
-/// data.
-///
-/// Unlike [PusTcCreator], this type does not require the user to provide the application data
-/// as a separate slice. Instead, it allows writing the application data directly into the provided
-/// serialization buffer. This eliminates the need for an intermediate buffer and the associated
-/// memory copy, improving performance, particularly when working with large payloads.
-///
-/// **Important:** The total length of the source data must be known and specified in advance
-/// to ensure correct serialization behavior.
-///
-/// Note that this abstraction intentionally omits certain trait implementations that are available
-/// on [PusTcCreator], as they are not applicable in this optimized usage pattern.
-pub struct PusTcCreatorWithReservedAppData<'buf> {
-    buf: &'buf mut [u8],
-    app_data_offset: usize,
-    full_len: usize,
-}
-
-impl<'buf> PusTcCreatorWithReservedAppData<'buf> {
-    /// Generates a new instance with reserved space for the user application data.
-    ///
-    /// # Arguments
-    ///
-    /// * `sp_header` - Space packet header information. The correct packet type and the secondary
-    ///   header flag are set correctly by the constructor.
-    /// * `sec_header` - Information contained in the secondary header, including the service
-    ///   and subservice type
-    /// * `app_data_len` - Custom application data length
-    #[inline]
-    pub fn new(
-        buf: &'buf mut [u8],
-        mut sp_header: SpHeader,
-        sec_header: PusTcSecondaryHeader,
-        app_data_len: usize,
-    ) -> Result<Self, ByteConversionError> {
-        sp_header.set_packet_type(PacketType::Tc);
-        sp_header.set_sec_header_flag();
-        let len_written = PUS_TC_MIN_LEN_WITHOUT_APP_DATA + app_data_len;
-        if len_written > buf.len() {
-            return Err(ByteConversionError::ToSliceTooSmall {
-                found: buf.len(),
-                expected: len_written,
-            });
-        }
-        sp_header.data_len = len_written as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
-        Self::write_to_bytes_partially(buf, sp_header, sec_header, app_data_len)
-    }
-
-    fn write_to_bytes_partially(
-        buf: &'buf mut [u8],
-        sp_header: SpHeader,
-        sec_header: PusTcSecondaryHeader,
-        app_data_len: usize,
-    ) -> Result<Self, ByteConversionError> {
-        let mut curr_idx = 0;
-        sp_header.write_to_be_bytes(&mut buf[0..CCSDS_HEADER_LEN])?;
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header_len = size_of::<zc::PusTcSecondaryHeader>();
-        let sec_header_zc = zc::PusTcSecondaryHeader::try_from(sec_header).unwrap();
-        sec_header_zc
-            .write_to(&mut buf[curr_idx..curr_idx + sec_header_len])
-            .map_err(|_| ByteConversionError::ZeroCopyToError)?;
-        curr_idx += sec_header_len;
-        let app_data_offset = curr_idx;
-        curr_idx += app_data_len;
-        Ok(Self {
-            buf,
-            app_data_offset,
-            full_len: curr_idx + 2,
-        })
-    }
-
-    #[inline]
-    pub const fn len_written(&self) -> usize {
-        self.full_len
-    }
-
-    /// Mutable access to the application data buffer.
-    #[inline]
-    pub fn app_data_mut(&mut self) -> &mut [u8] {
-        &mut self.buf[self.app_data_offset..self.full_len - 2]
-    }
-
-    /// Access to the source data buffer.
-    #[inline]
-    pub fn app_data(&self) -> &[u8] {
-        &self.buf[self.app_data_offset..self.full_len - 2]
-    }
-
-    #[inline]
-    pub fn app_data_len(&self) -> usize {
-        self.full_len - 2 - self.app_data_offset
-    }
-
-    /// Finalize the TC packet by calculating and writing the CRC16.
-    ///
-    /// Returns the full packet length.
-    pub fn finalize(self) -> usize {
-        let mut digest = CRC_CCITT_FALSE.digest();
-        digest.update(&self.buf[0..self.full_len - 2]);
-        self.buf[self.full_len - 2..self.full_len]
-            .copy_from_slice(&digest.finalize().to_be_bytes());
-        self.full_len
-    }
-
-    /// Finalize the TC packet by calculating and writing the CRC16 using a table-less
-    /// implementation.
-    ///
-    /// Returns the full packet length.
-    pub fn finalize_crc_no_table(self) -> usize {
-        let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
-        digest.update(&self.buf[0..self.full_len - 2]);
-        self.buf[self.full_len - 2..self.full_len]
-            .copy_from_slice(&digest.finalize().to_be_bytes());
-        self.full_len
-    }
-
-    /// Finalize the TC packet without writing the CRC16.
-    ///
-    /// Returns the length WITHOUT the CRC16.
-    #[inline]
-    pub fn finalize_no_crc(self) -> usize {
-        self.full_len - 2
-    }
-}
-
 /// 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
@ -633,22 +475,7 @@ 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. This function also performs a CRC
    /// check and will return an appropriate [PusError] if the check fails.
-    pub fn new(slice: &'raw_data [u8]) -> Result<Self, PusError> {
-        let pus_tc = Self::new_no_crc_check(slice)?;
-        verify_crc16_ccitt_false_from_raw_to_pus_error(pus_tc.raw_data(), pus_tc.crc16())?;
-        Ok(pus_tc)
-    }
-
-    /// Similar to [PusTcReader::new], but uses a table-less CRC16 algorithm which can reduce
-    /// binary size and memory usage.
-    pub fn new_crc_no_table(slice: &'raw_data [u8]) -> Result<Self, PusError> {
-        let pus_tc = Self::new_no_crc_check(slice)?;
-        verify_crc16_ccitt_false_from_raw_to_pus_error_no_table(pus_tc.raw_data(), pus_tc.crc16())?;
-        Ok(pus_tc)
-    }
-
-    /// Creates a new instance without performing a CRC check.
-    pub fn new_no_crc_check(slice: &'raw_data [u8]) -> Result<Self, 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(ByteConversionError::FromSliceTooSmall {
@ -675,19 +502,21 @@ impl<'raw_data> PusTcReader<'raw_data> {
            }
            .into());
        }
-        let sec_header = zc::PusTcSecondaryHeader::read_from_bytes(
+        let sec_header = zc::PusTcSecondaryHeader::from_bytes(
            &slice[current_idx..current_idx + PUC_TC_SECONDARY_HEADER_LEN],
        )
-        .map_err(|_| ByteConversionError::ZeroCopyFromError)?;
+        .ok_or(ByteConversionError::ZeroCopyFromError)?;
        current_idx += PUC_TC_SECONDARY_HEADER_LEN;
        let raw_data = &slice[0..total_len];
-        Ok(Self {
+        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, 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))
    }

    #[inline]
@ -709,11 +538,6 @@ impl<'raw_data> PusTcReader<'raw_data> {
    pub fn sp_header(&self) -> &SpHeader {
        &self.sp_header
    }
-
-    #[inline]
-    pub fn crc16(&self) -> u16 {
-        self.crc16
-    }
 }

 impl PartialEq for PusTcReader<'_> {
@ -743,7 +567,7 @@ impl PusPacket for PusTcReader<'_> {
    }

    #[inline]
-    fn opt_crc16(&self) -> Option<u16> {
+    fn crc16(&self) -> Option<u16> {
        Some(self.crc16)
    }
 }
@ -783,6 +607,8 @@ impl PartialEq<PusTcReader<'_>> for PusTcCreator<'_> {

 #[cfg(all(test, feature = "std"))]
 mod tests {
+    use std::error::Error;
+
    use super::*;
    use crate::ecss::PusVersion::PusC;
    use crate::ecss::{PusError, PusPacket, WritablePusPacket};
@ -824,74 +650,11 @@ mod tests {
            .expect("Error writing TC to buffer");
        assert_eq!(size, 13);
        assert_eq!(
-            pus_tc.opt_crc16().unwrap(),
+            pus_tc.crc16().unwrap(),
            u16::from_be_bytes(test_buf[size - 2..size].try_into().unwrap())
        );
    }

-    #[test]
-    fn test_serialization_with_trait_1() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = WritablePusPacket::write_to_bytes(&pus_tc, test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(size, 13);
-        assert_eq!(
-            pus_tc.opt_crc16().unwrap(),
-            u16::from_be_bytes(test_buf[size - 2..size].try_into().unwrap())
-        );
-    }
-
-    #[test]
-    fn test_serialization_with_trait_2() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = WritablePusPacket::write_to_bytes_crc_no_table(&pus_tc, test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(size, 13);
-        assert_eq!(
-            pus_tc.opt_crc16().unwrap(),
-            u16::from_be_bytes(test_buf[size - 2..size].try_into().unwrap())
-        );
-    }
-
-    #[test]
-    fn test_serialization_crc_no_table() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes_crc_no_table(test_buf.as_mut_slice())
-            .expect("error writing tc to buffer");
-        assert_eq!(size, 13);
-        assert_eq!(
-            pus_tc.opt_crc16().unwrap(),
-            u16::from_be_bytes(test_buf[size - 2..size].try_into().unwrap())
-        );
-    }
-
-    #[test]
-    fn test_serialization_no_crc() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes_no_crc(test_buf.as_mut_slice())
-            .expect("error writing tc to buffer");
-        assert_eq!(size, 11);
-        assert_eq!(test_buf[11], 0);
-        assert_eq!(test_buf[12], 0);
-    }
-
-    #[test]
-    fn test_serialization_no_crc_with_trait() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = WritablePusPacket::write_to_bytes_no_crc(&pus_tc, test_buf.as_mut_slice())
-            .expect("error writing tc to buffer");
-        assert_eq!(size, 11);
-        assert_eq!(test_buf[11], 0);
-        assert_eq!(test_buf[12], 0);
-    }
-
    #[test]
    fn test_deserialization() {
        let pus_tc = base_ping_tc_simple_ctor();
@ -900,48 +663,9 @@ mod tests {
            .write_to_bytes(test_buf.as_mut_slice())
            .expect("Error writing TC to buffer");
        assert_eq!(size, 13);
-        let tc_from_raw =
+        let (tc_from_raw, size) =
            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(tc_from_raw.total_len(), 13);
-        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);
-    }
-
-    #[test]
-    fn test_deserialization_alt_ctor() {
-        let sph = SpHeader::new_for_unseg_tc_checked(0x02, 0x34, 0).unwrap();
-        let tc_header = PusTcSecondaryHeader::new_simple(17, 1);
-        let mut test_buf: [u8; 32] = [0; 32];
-        let mut pus_tc =
-            PusTcCreatorWithReservedAppData::new(&mut test_buf, sph, tc_header, 0).unwrap();
-        assert_eq!(pus_tc.len_written(), 13);
-        assert_eq!(pus_tc.app_data_len(), 0);
-        assert_eq!(pus_tc.app_data(), &[]);
-        assert_eq!(pus_tc.app_data_mut(), &[]);
-        let size = pus_tc.finalize();
        assert_eq!(size, 13);
-        let tc_from_raw =
-            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(tc_from_raw.total_len(), 13);
-        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);
-    }
-
-    #[test]
-    fn test_deserialization_no_table() {
-        let pus_tc = base_ping_tc_simple_ctor();
-        let mut test_buf: [u8; 32] = [0; 32];
-        let size = pus_tc
-            .write_to_bytes(test_buf.as_mut_slice())
-            .expect("Error writing TC to buffer");
-        assert_eq!(size, 13);
-        let tc_from_raw = PusTcReader::new_crc_no_table(&test_buf)
-            .expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(tc_from_raw.total_len(), 13);
        verify_test_tc_with_reader(&tc_from_raw, false, 13);
        assert!(tc_from_raw.user_data().is_empty());
        verify_test_tc_raw(&test_buf);
@ -953,9 +677,9 @@ mod tests {
        let pus_tc = base_ping_tc_simple_ctor();
        let tc_vec = pus_tc.to_vec().expect("Error writing TC to buffer");
        assert_eq!(tc_vec.len(), 13);
-        let tc_from_raw = PusTcReader::new(tc_vec.as_slice())
+        let (tc_from_raw, size) = PusTcReader::new(tc_vec.as_slice())
            .expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(tc_from_raw.total_len(), 13);
+        assert_eq!(size, 13);
        verify_test_tc_with_reader(&tc_from_raw, false, 13);
        assert!(tc_from_raw.user_data().is_empty());
        verify_test_tc_raw(&tc_vec);
@ -970,7 +694,6 @@ mod tests {
        tc.update_ccsds_data_len();
        assert_eq!(tc.data_len(), 6);
    }
-
    #[test]
    fn test_deserialization_with_app_data() {
        let pus_tc = base_ping_tc_simple_ctor_with_app_data(&[1, 2, 3]);
@ -979,15 +702,15 @@ mod tests {
            .write_to_bytes(test_buf.as_mut_slice())
            .expect("Error writing TC to buffer");
        assert_eq!(size, 16);
-        let tc_from_raw =
+        let (tc_from_raw, size) =
            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
-        assert_eq!(tc_from_raw.total_len(), 16);
+        assert_eq!(size, 16);
        verify_test_tc_with_reader(&tc_from_raw, true, 16);
        let user_data = tc_from_raw.user_data();
        assert_eq!(tc_from_raw.user_data(), tc_from_raw.app_data());
        assert_eq!(tc_from_raw.raw_data(), &test_buf[..size]);
        assert_eq!(
-            tc_from_raw.opt_crc16().unwrap(),
+            tc_from_raw.crc16().unwrap(),
            u16::from_be_bytes(test_buf[size - 2..size].try_into().unwrap())
        );
        assert_eq!(user_data[0], 1);
@ -1002,9 +725,9 @@ mod tests {
        pus_tc
            .write_to_bytes(test_buf.as_mut_slice())
            .expect("Error writing TC to buffer");
-        let tc_from_raw_0 =
+        let (tc_from_raw_0, _) =
            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
-        let tc_from_raw_1 =
+        let (tc_from_raw_1, _) =
            PusTcReader::new(&test_buf).expect("Creating PUS TC struct from raw buffer failed");
        assert_eq!(tc_from_raw_0, tc_from_raw_1);
    }
@ -1073,17 +796,22 @@ mod tests {
        let res = pus_tc.write_to_bytes(test_buf.as_mut_slice());
        assert!(res.is_err());
        let err = res.unwrap_err();
-        assert_eq!(
-            err,
-            ByteConversionError::ToSliceTooSmall {
-                found: 12,
-                expected: 13
-            }
-        );
-        assert_eq!(
-            err.to_string(),
-            "target slice with size 12 is too small, expected size of at least 13"
-        );
+        if let PusError::ByteConversion(e) = err {
+            assert_eq!(
+                e,
+                ByteConversionError::ToSliceTooSmall {
+                    found: 12,
+                    expected: 13
+                }
+            );
+            assert_eq!(
+                err.to_string(),
+                "pus error: target slice with size 12 is too small, expected size of at least 13"
+            );
+            assert_eq!(err.source().unwrap().to_string(), e.to_string());
+        } else {
+            panic!("unexpected error {err}");
+        }
    }

    #[test]
@ -1151,7 +879,7 @@ mod tests {
        assert_eq!(*tc.sp_header(), comp_header);
    }

-    fn verify_test_tc_generic(tc: &(impl PusPacket + GenericPusTcSecondaryHeader)) {
+    fn verify_test_tc_generic(tc: &(impl CcsdsPacket + PusPacket + GenericPusTcSecondaryHeader)) {
        assert_eq!(PusPacket::service(tc), 17);
        assert_eq!(GenericPusTcSecondaryHeader::service(tc), 17);
        assert_eq!(PusPacket::subservice(tc), 1);
@ -1215,8 +943,8 @@ 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, PusTcReader::new(&buf).unwrap());
-        assert_eq!(PusTcReader::new(&buf).unwrap(), pus_tc);
+        assert_eq!(pus_tc, PusTcReader::new(&buf).unwrap().0);
+        assert_eq!(PusTcReader::new(&buf).unwrap().0, pus_tc);
    }

    #[test]
--- a/src/ecss/tm.rs
+++ b/src/ecss/tm.rs
@ -35,14 +35,13 @@
 //! println!("{:?}", &test_buf[0..written_size]);
 //!
 //! // Deserialize from the raw byte representation
-//! let ping_tm_reader = PusTmReader::new(&test_buf, 7).expect("Deserialization failed");
-//! assert_eq!(written_size, ping_tm_reader.total_len());
+//! let (ping_tm_reader, read_size) = PusTmReader::new(&test_buf, 7).expect("Deserialization failed");
+//! assert_eq!(written_size, read_size);
 //! assert_eq!(ping_tm_reader.service(), 17);
 //! assert_eq!(ping_tm_reader.subservice(), 2);
 //! assert_eq!(ping_tm_reader.apid(), 0x02);
 //! assert_eq!(ping_tm_reader.timestamp(), &time_buf);
 //! ```
-use crate::crc::{CRC_CCITT_FALSE, CRC_CCITT_FALSE_NO_TABLE};
 use crate::ecss::{
    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,
@ -50,12 +49,12 @@ use crate::ecss::{
 };
 use crate::{
    ByteConversionError, CcsdsPacket, PacketType, SequenceFlags, SpHeader, CCSDS_HEADER_LEN,
-    MAX_APID, MAX_SEQ_COUNT,
+    CRC_CCITT_FALSE, MAX_APID, MAX_SEQ_COUNT,
 };
 use core::mem::size_of;
 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};
-use zerocopy::{FromBytes, IntoBytes};
+use zerocopy::AsBytes;

 #[cfg(feature = "alloc")]
 use alloc::vec::Vec;
@ -65,8 +64,6 @@ use crate::time::{TimeWriter, TimestampError};

 use self::zc::PusTmSecHeaderWithoutTimestamp;

-use super::verify_crc16_ccitt_false_from_raw_to_pus_error_no_table;
-
 pub trait IsPusTelemetry {}

 /// Length without timestamp
@ -86,9 +83,9 @@ pub trait GenericPusTmSecondaryHeader {
 pub mod zc {
    use super::GenericPusTmSecondaryHeader;
    use crate::ecss::{PusError, PusVersion};
-    use zerocopy::{FromBytes, Immutable, IntoBytes, NetworkEndian, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, NetworkEndian, Unaligned, U16};

-    #[derive(FromBytes, IntoBytes, Immutable, Unaligned)]
+    #[derive(FromBytes, FromZeroes, AsBytes, Unaligned)]
    #[repr(C)]
    pub struct PusTmSecHeaderWithoutTimestamp {
        pus_version_and_sc_time_ref_status: u8,
@ -120,10 +117,20 @@ pub mod zc {
        }
    }

+    impl PusTmSecHeaderWithoutTimestamp {
+        pub fn write_to_bytes(&self, slice: &mut [u8]) -> Option<()> {
+            self.write_to(slice)
+        }
+
+        pub fn from_bytes(slice: &[u8]) -> Option<Self> {
+            Self::read_from(slice)
+        }
+    }
+
    impl GenericPusTmSecondaryHeader for PusTmSecHeaderWithoutTimestamp {
        #[inline]
        fn pus_version(&self) -> PusVersion {
-            PusVersion::try_from((self.pus_version_and_sc_time_ref_status >> 4) & 0b1111)
+            PusVersion::try_from(self.pus_version_and_sc_time_ref_status >> 4 & 0b1111)
                .unwrap_or(PusVersion::Invalid)
        }

@ -280,13 +287,13 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {
    /// # Arguments
    ///
    /// * `sp_header` - Space packet header information. The correct packet type and the secondary
-    ///   header flag are set correctly by the constructor.
+    ///     header flag are set correctly by the constructor.
    /// * `sec_header` - Information contained in the secondary header, including the service
-    ///   and subservice type
+    ///     and subservice type
    /// * `source_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, [Self::update_ccsds_data_len] can be called to set
-    ///   the correct value to this field manually
+    ///     field. If this is not set to true, [Self::update_ccsds_data_len] can be called to set
+    ///     the correct value to this field manually
    #[inline]
    pub fn new(
        mut sp_header: SpHeader,
@ -392,45 +399,33 @@ impl<'time, 'src_data> PusTmCreator<'time, 'src_data> {

    /// Write the raw PUS byte representation to a provided buffer.
    pub fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, ByteConversionError> {
-        let writer_unfinalized = self.common_write(slice)?;
-        Ok(writer_unfinalized.finalize())
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes_crc_no_table(
-        &self,
-        slice: &mut [u8],
-    ) -> Result<usize, ByteConversionError> {
-        let writer_unfinalized = self.common_write(slice)?;
-        Ok(writer_unfinalized.finalize_crc_no_table())
-    }
-
-    /// Write the raw PUS byte representation to a provided buffer.
-    pub fn write_to_bytes_no_crc(&self, slice: &mut [u8]) -> Result<usize, ByteConversionError> {
-        let writer_unfinalized = self.common_write(slice)?;
-        Ok(writer_unfinalized.finalize_no_crc())
-    }
-
-    fn common_write<'a>(
-        &self,
-        slice: &'a mut [u8],
-    ) -> Result<PusTmCreatorWithReservedSourceData<'a>, ByteConversionError> {
-        if self.len_written() > slice.len() {
+        let mut curr_idx = 0;
+        let total_size = self.len_written();
+        if total_size > slice.len() {
            return Err(ByteConversionError::ToSliceTooSmall {
                found: slice.len(),
-                expected: self.len_written(),
+                expected: total_size,
            });
        }
-        let mut writer_unfinalized = PusTmCreatorWithReservedSourceData::write_to_bytes_partially(
-            slice,
-            self.sp_header,
-            self.sec_header,
-            self.source_data.len(),
-        )?;
-        writer_unfinalized
-            .source_data_mut()
-            .copy_from_slice(self.source_data);
-        Ok(writer_unfinalized)
+        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)
    }

    /// Append the raw PUS byte representation to a provided [alloc::vec::Vec]
@ -461,21 +456,12 @@ impl WritablePusPacket for PusTmCreator<'_, '_> {
            + self.source_data.len()
    }
    /// Write the raw PUS byte representation to a provided buffer.
-    fn write_to_bytes_no_crc(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        Ok(Self::write_to_bytes_no_crc(self, slice)?)
-    }
-
    fn write_to_bytes(&self, slice: &mut [u8]) -> Result<usize, PusError> {
        Ok(Self::write_to_bytes(self, slice)?)
    }
-
-    fn write_to_bytes_crc_no_table(&self, slice: &mut [u8]) -> Result<usize, PusError> {
-        Ok(Self::write_to_bytes_crc_no_table(self, slice)?)
-    }
 }

 impl PartialEq for PusTmCreator<'_, '_> {
-    #[inline]
    fn eq(&self, other: &Self) -> bool {
        self.sp_header == other.sp_header
            && self.sec_header == other.sec_header
@ -503,7 +489,7 @@ impl PusPacket for PusTmCreator<'_, '_> {
    }

    #[inline]
-    fn opt_crc16(&self) -> Option<u16> {
+    fn crc16(&self) -> Option<u16> {
        Some(self.calc_own_crc16())
    }
 }
@ -527,136 +513,6 @@ impl GenericPusTmSecondaryHeader for PusTmCreator<'_, '_> {

 impl IsPusTelemetry for PusTmCreator<'_, '_> {}

-/// A specialized variant of [PusTmCreator] designed for efficiency when handling large source
-/// data.
-///
-/// Unlike [PusTmCreator], this type does not require the user to provide the source data
-/// as a separate slice. Instead, it allows writing the source data directly into the provided
-/// serialization buffer. This eliminates the need for an intermediate buffer and the associated
-/// memory copy, improving performance, particularly when working with large payloads.
-///
-/// **Important:** The total length of the source data must be known and specified in advance
-/// to ensure correct serialization behavior.
-///
-/// Note that this abstraction intentionally omits certain trait implementations that are available
-/// on [PusTmCreator], as they are not applicable in this optimized usage pattern.
-pub struct PusTmCreatorWithReservedSourceData<'buf> {
-    buf: &'buf mut [u8],
-    source_data_offset: usize,
-    full_len: usize,
-}
-
-impl<'buf> PusTmCreatorWithReservedSourceData<'buf> {
-    /// Generates a new instance with reserved space for the user source data.
-    ///
-    /// # Arguments
-    ///
-    /// * `sp_header` - Space packet header information. The correct packet type and the secondary
-    ///   header flag are set correctly by the constructor.
-    /// * `sec_header` - Information contained in the secondary header, including the service
-    ///   and subservice type
-    /// * `src_data_len` - Custom source data length
-    #[inline]
-    pub fn new(
-        buf: &'buf mut [u8],
-        mut sp_header: SpHeader,
-        sec_header: PusTmSecondaryHeader,
-        src_data_len: usize,
-    ) -> Result<Self, ByteConversionError> {
-        sp_header.set_packet_type(PacketType::Tm);
-        sp_header.set_sec_header_flag();
-        let len_written =
-            PUS_TM_MIN_LEN_WITHOUT_SOURCE_DATA + sec_header.timestamp.len() + src_data_len;
-        if len_written > buf.len() {
-            return Err(ByteConversionError::ToSliceTooSmall {
-                found: buf.len(),
-                expected: len_written,
-            });
-        }
-        sp_header.data_len = len_written as u16 - size_of::<crate::zc::SpHeader>() as u16 - 1;
-        Self::write_to_bytes_partially(buf, sp_header, sec_header, src_data_len)
-    }
-
-    fn write_to_bytes_partially(
-        buf: &'buf mut [u8],
-        sp_header: SpHeader,
-        sec_header: PusTmSecondaryHeader,
-        src_data_len: usize,
-    ) -> Result<Self, ByteConversionError> {
-        let mut curr_idx = 0;
-        sp_header.write_to_be_bytes(&mut buf[0..CCSDS_HEADER_LEN])?;
-        curr_idx += CCSDS_HEADER_LEN;
-        let sec_header_len = size_of::<zc::PusTmSecHeaderWithoutTimestamp>();
-        let sec_header_zc = zc::PusTmSecHeaderWithoutTimestamp::try_from(sec_header).unwrap();
-        sec_header_zc
-            .write_to(&mut buf[curr_idx..curr_idx + sec_header_len])
-            .map_err(|_| ByteConversionError::ZeroCopyToError)?;
-        curr_idx += sec_header_len;
-        buf[curr_idx..curr_idx + sec_header.timestamp.len()].copy_from_slice(sec_header.timestamp);
-        curr_idx += sec_header.timestamp.len();
-        let source_data_offset = curr_idx;
-        curr_idx += src_data_len;
-        Ok(Self {
-            buf,
-            source_data_offset,
-            full_len: curr_idx + 2,
-        })
-    }
-
-    #[inline]
-    pub const fn len_written(&self) -> usize {
-        self.full_len
-    }
-
-    /// Mutable access to the source data buffer.
-    #[inline]
-    pub fn source_data_mut(&mut self) -> &mut [u8] {
-        &mut self.buf[self.source_data_offset..self.full_len - 2]
-    }
-
-    /// Access to the source data buffer.
-    #[inline]
-    pub fn source_data(&self) -> &[u8] {
-        &self.buf[self.source_data_offset..self.full_len - 2]
-    }
-
-    #[inline]
-    pub fn source_data_len(&self) -> usize {
-        self.full_len - 2 - self.source_data_offset
-    }
-
-    /// Finalize the TM packet by calculating and writing the CRC16.
-    ///
-    /// Returns the full packet length.
-    pub fn finalize(self) -> usize {
-        let mut digest = CRC_CCITT_FALSE.digest();
-        digest.update(&self.buf[0..self.full_len - 2]);
-        self.buf[self.full_len - 2..self.full_len]
-            .copy_from_slice(&digest.finalize().to_be_bytes());
-        self.full_len
-    }
-
-    /// Finalize the TM packet by calculating and writing the CRC16 using a table-less
-    /// implementation.
-    ///
-    /// Returns the full packet length.
-    pub fn finalize_crc_no_table(self) -> usize {
-        let mut digest = CRC_CCITT_FALSE_NO_TABLE.digest();
-        digest.update(&self.buf[0..self.full_len - 2]);
-        self.buf[self.full_len - 2..self.full_len]
-            .copy_from_slice(&digest.finalize().to_be_bytes());
-        self.full_len
-    }
-
-    /// Finalize the TM packet without writing the CRC16.
-    ///
-    /// Returns the length WITHOUT the CRC16.
-    #[inline]
-    pub fn finalize_no_crc(self) -> usize {
-        self.full_len - 2
-    }
-}
-
 /// This class models the PUS C telemetry packet. It is the primary data structure to read
 /// a telemetry packet from raw bytes.
 ///
@ -688,26 +544,7 @@ impl<'raw_data> PusTmReader<'raw_data> {
    ///
    /// This function will check the CRC-16 of the PUS packet and will return an appropriate
    /// [PusError] if the check fails.
-    pub fn new(slice: &'raw_data [u8], timestamp_len: usize) -> Result<Self, PusError> {
-        let tc = Self::new_no_crc_check(slice, timestamp_len)?;
-        verify_crc16_ccitt_false_from_raw_to_pus_error(tc.raw_data(), tc.crc16)?;
-        Ok(tc)
-    }
-
-    /// Like [PusTmReader::new] but uses a table-less CRC implementation.
-    pub fn new_crc_no_table(
-        slice: &'raw_data [u8],
-        timestamp_len: usize,
-    ) -> Result<Self, PusError> {
-        let tc = Self::new_no_crc_check(slice, timestamp_len)?;
-        verify_crc16_ccitt_false_from_raw_to_pus_error_no_table(tc.raw_data(), tc.crc16)?;
-        Ok(tc)
-    }
-
-    pub fn new_no_crc_check(
-        slice: &'raw_data [u8],
-        timestamp_len: usize,
-    ) -> Result<Self, 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(ByteConversionError::FromSliceTooSmall {
@ -734,10 +571,10 @@ impl<'raw_data> PusTmReader<'raw_data> {
            }
            .into());
        }
-        let sec_header_zc = zc::PusTmSecHeaderWithoutTimestamp::read_from_bytes(
+        let sec_header_zc = zc::PusTmSecHeaderWithoutTimestamp::from_bytes(
            &slice[current_idx..current_idx + PUS_TM_MIN_SEC_HEADER_LEN],
        )
-        .map_err(|_| ByteConversionError::ZeroCopyFromError)?;
+        .ok_or(ByteConversionError::ZeroCopyFromError)?;
        current_idx += PUS_TM_MIN_SEC_HEADER_LEN;
        let zc_sec_header_wrapper = zc::PusTmSecHeader {
            zc_header: sec_header_zc,
@ -745,13 +582,15 @@ impl<'raw_data> PusTmReader<'raw_data> {
        };
        current_idx += timestamp_len;
        let raw_data = &slice[0..total_len];
-        Ok(Self {
+        let pus_tm = Self {
            sp_header,
            sec_header: PusTmSecondaryHeader::try_from(zc_sec_header_wrapper).unwrap(),
            raw_data: &slice[0..total_len],
            source_data: user_data_from_raw(current_idx, total_len, slice)?,
            crc16: crc_from_raw_data(raw_data)?,
-        })
+        };
+        verify_crc16_ccitt_false_from_raw_to_pus_error(raw_data, pus_tm.crc16)?;
+        Ok((pus_tm, total_len))
    }

    #[inline]
@ -769,11 +608,6 @@ impl<'raw_data> PusTmReader<'raw_data> {
        self.sec_header.timestamp
    }

-    #[inline]
-    pub fn crc16(&self) -> u16 {
-        self.crc16
-    }
-
    /// This function will return the slice [Self] was constructed from.
    #[inline]
    pub fn raw_data(&self) -> &[u8] {
@ -810,8 +644,8 @@ impl PusPacket for PusTmReader<'_> {
    }

    #[inline]
-    fn opt_crc16(&self) -> Option<u16> {
-        Some(self.crc16())
+    fn crc16(&self) -> Option<u16> {
+        Some(self.crc16)
    }
 }

@ -876,7 +710,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
        if raw_tm_len < CCSDS_HEADER_LEN + PUS_TM_MIN_SEC_HEADER_LEN + timestamp_len {
            return None;
        }
-        let sp_header = crate::zc::SpHeader::read_from_bytes(&raw_tm[0..CCSDS_HEADER_LEN]).unwrap();
+        let sp_header = crate::zc::SpHeader::from_bytes(&raw_tm[0..CCSDS_HEADER_LEN]).unwrap();
        if raw_tm_len < sp_header.total_len() {
            return None;
        }
@ -917,7 +751,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
    #[inline]
    pub fn sp_header(&self) -> crate::zc::SpHeader {
        // Valid minimum length of packet was checked before.
-        crate::zc::SpHeader::read_from_bytes(&self.raw_tm[0..CCSDS_HEADER_LEN]).unwrap()
+        crate::zc::SpHeader::from_bytes(&self.raw_tm[0..CCSDS_HEADER_LEN]).unwrap()
    }

    /// Helper API to generate the portion of the secondary header without a timestamp from the
@ -925,7 +759,7 @@ impl<'raw> PusTmZeroCopyWriter<'raw> {
    #[inline]
    pub fn sec_header_without_timestamp(&self) -> PusTmSecHeaderWithoutTimestamp {
        // Valid minimum length of packet was checked before.
-        PusTmSecHeaderWithoutTimestamp::read_from_bytes(
+        PusTmSecHeaderWithoutTimestamp::from_bytes(
            &self.raw_tm[CCSDS_HEADER_LEN..CCSDS_HEADER_LEN + PUS_TM_MIN_SEC_HEADER_LEN],
        )
        .unwrap()
@ -998,7 +832,7 @@ impl PusPacket for PusTmZeroCopyWriter<'_> {
    }

    #[inline]
-    fn opt_crc16(&self) -> Option<u16> {
+    fn crc16(&self) -> Option<u16> {
        Some(u16::from_be_bytes(
            self.raw_tm[self.sp_header().total_len() - 2..self.sp_header().total_len()]
                .try_into()
@ -1094,66 +928,7 @@ mod tests {
            .write_to_bytes(&mut buf)
            .expect("Serialization failed");
        assert_eq!(ser_len, 22);
-        verify_raw_ping_reply(pus_tm.opt_crc16(), &buf);
-    }
-
-    #[test]
-    fn test_serialization_no_source_data_alt_ctor() {
-        let timestamp = dummy_timestamp();
-        let sph = SpHeader::new_for_unseg_tm_checked(0x123, 0x234, 0).unwrap();
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let mut pus_tm =
-            PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tm_header, 0).unwrap();
-        assert_eq!(pus_tm.source_data_len(), 0);
-        assert_eq!(pus_tm.source_data(), &[]);
-        assert_eq!(pus_tm.source_data_mut(), &[]);
-        let ser_len = pus_tm.finalize();
-        assert_eq!(ser_len, 22);
-        verify_raw_ping_reply(None, &buf);
-    }
-
-    #[test]
-    fn test_serialization_no_source_data_alt_ctor_no_crc() {
-        let timestamp = dummy_timestamp();
-        let sph = SpHeader::new_for_unseg_tm_checked(0x123, 0x234, 0).unwrap();
-        let tm_header = PusTmSecondaryHeader::new_simple(17, 2, timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let mut pus_tm =
-            PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tm_header, 0).unwrap();
-        assert_eq!(pus_tm.source_data_len(), 0);
-        assert_eq!(pus_tm.source_data(), &[]);
-        assert_eq!(pus_tm.source_data_mut(), &[]);
-        let ser_len = pus_tm.finalize_no_crc();
-        assert_eq!(ser_len, 20);
-        verify_raw_ping_reply_no_crc(&buf);
-        assert_eq!(buf[20], 0);
-        assert_eq!(buf[21], 0);
-    }
-
-    #[test]
-    fn test_serialization_no_source_data_no_table() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes_crc_no_table(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        verify_raw_ping_reply(pus_tm.opt_crc16(), &buf);
-    }
-
-    #[test]
-    fn test_serialization_no_source_data_no_crc() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes_no_crc(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 20);
-        assert_eq!(buf[20], 0);
-        assert_eq!(buf[21], 0);
+        verify_raw_ping_reply(pus_tm.crc16().unwrap(), &buf);
    }

    #[test]
@ -1170,46 +945,6 @@ mod tests {
        assert_eq!(buf[22], 3);
    }

-    #[test]
-    fn test_serialization_with_source_data_alt_ctor() {
-        let src_data = &[1, 2, 3];
-        let mut buf: [u8; 32] = [0; 32];
-        let sph = SpHeader::new_for_unseg_tm_checked(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, dummy_timestamp());
-        let mut hk_reply_unwritten =
-            PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tc_header, 3).unwrap();
-        assert_eq!(hk_reply_unwritten.source_data_len(), 3);
-        assert_eq!(hk_reply_unwritten.source_data(), &[0, 0, 0]);
-        assert_eq!(hk_reply_unwritten.source_data_mut(), &[0, 0, 0]);
-        let source_data_mut = hk_reply_unwritten.source_data_mut();
-        source_data_mut.copy_from_slice(src_data);
-        let ser_len = hk_reply_unwritten.finalize();
-        assert_eq!(ser_len, 25);
-        assert_eq!(buf[20], 1);
-        assert_eq!(buf[21], 2);
-        assert_eq!(buf[22], 3);
-    }
-
-    #[test]
-    fn test_serialization_with_source_data_alt_ctor_no_table() {
-        let src_data = &[1, 2, 3];
-        let mut buf: [u8; 32] = [0; 32];
-        let sph = SpHeader::new_for_unseg_tm_checked(0x123, 0x234, 0).unwrap();
-        let tc_header = PusTmSecondaryHeader::new_simple(3, 5, dummy_timestamp());
-        let mut hk_reply_unwritten =
-            PusTmCreatorWithReservedSourceData::new(&mut buf, sph, tc_header, 3).unwrap();
-        assert_eq!(hk_reply_unwritten.source_data_len(), 3);
-        assert_eq!(hk_reply_unwritten.source_data(), &[0, 0, 0]);
-        assert_eq!(hk_reply_unwritten.source_data_mut(), &[0, 0, 0]);
-        let source_data_mut = hk_reply_unwritten.source_data_mut();
-        source_data_mut.copy_from_slice(src_data);
-        let ser_len = hk_reply_unwritten.finalize_crc_no_table();
-        assert_eq!(ser_len, 25);
-        assert_eq!(buf[20], 1);
-        assert_eq!(buf[21], 2);
-        assert_eq!(buf[22], 3);
-    }
-
    #[test]
    fn test_setters() {
        let timestamp = dummy_timestamp();
@ -1230,12 +965,11 @@ mod tests {
        let pus_tm = base_ping_reply_full_ctor(timestamp);
        let tm_vec = pus_tm.to_vec().expect("Serialization failed");
        assert_eq!(tm_vec.len(), 22);
-        let tm_deserialized =
+        let (tm_deserialized, size) =
            PusTmReader::new(tm_vec.as_slice(), 7).expect("Deserialization failed");
-        assert_eq!(tm_vec.len(), tm_deserialized.total_len());
+        assert_eq!(tm_vec.len(), size);
        verify_ping_reply_with_reader(&tm_deserialized, false, 22, dummy_timestamp());
    }
-
    #[test]
    fn test_deserialization_no_source_data() {
        let timestamp = dummy_timestamp();
@ -1245,48 +979,13 @@ mod tests {
            .write_to_bytes(&mut buf)
            .expect("Serialization failed");
        assert_eq!(ser_len, 22);
-        let tm_deserialized = PusTmReader::new(&buf, 7).expect("Deserialization failed");
-        assert_eq!(ser_len, tm_deserialized.total_len());
+        let (tm_deserialized, size) = PusTmReader::new(&buf, 7).expect("Deserialization failed");
+        assert_eq!(ser_len, size);
        assert_eq!(tm_deserialized.user_data(), tm_deserialized.source_data());
        assert_eq!(tm_deserialized.raw_data(), &buf[..ser_len]);
-        assert_eq!(tm_deserialized.crc16(), pus_tm.opt_crc16().unwrap());
+        assert_eq!(tm_deserialized.crc16().unwrap(), pus_tm.crc16().unwrap());
        verify_ping_reply_with_reader(&tm_deserialized, false, 22, dummy_timestamp());
    }
-
-    #[test]
-    fn test_deserialization_no_source_data_with_trait() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len =
-            WritablePusPacket::write_to_bytes(&pus_tm, &mut buf).expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        let tm_deserialized = PusTmReader::new(&buf, 7).expect("Deserialization failed");
-        assert_eq!(ser_len, tm_deserialized.total_len());
-        assert_eq!(tm_deserialized.user_data(), tm_deserialized.source_data());
-        assert_eq!(tm_deserialized.raw_data(), &buf[..ser_len]);
-        assert_eq!(tm_deserialized.crc16(), pus_tm.opt_crc16().unwrap());
-        verify_ping_reply_with_reader(&tm_deserialized, false, 22, dummy_timestamp());
-    }
-
-    #[test]
-    fn test_deserialization_no_table() {
-        let timestamp = dummy_timestamp();
-        let pus_tm = base_ping_reply_full_ctor(timestamp);
-        let mut buf: [u8; 32] = [0; 32];
-        let ser_len = pus_tm
-            .write_to_bytes(&mut buf)
-            .expect("Serialization failed");
-        assert_eq!(ser_len, 22);
-        let tm_deserialized =
-            PusTmReader::new_crc_no_table(&buf, 7).expect("Deserialization failed");
-        assert_eq!(ser_len, tm_deserialized.total_len());
-        assert_eq!(tm_deserialized.user_data(), tm_deserialized.source_data());
-        assert_eq!(tm_deserialized.raw_data(), &buf[..ser_len]);
-        assert_eq!(tm_deserialized.crc16(), pus_tm.opt_crc16().unwrap());
-        verify_ping_reply_with_reader(&tm_deserialized, false, 22, dummy_timestamp());
-    }
-
    #[test]
    fn test_deserialization_faulty_crc() {
        let timestamp = dummy_timestamp();
@ -1353,7 +1052,7 @@ mod tests {
        let res = pus_tm.append_to_vec(&mut vec);
        assert!(res.is_ok());
        assert_eq!(res.unwrap(), 22);
-        verify_raw_ping_reply(pus_tm.opt_crc16(), vec.as_slice());
+        verify_raw_ping_reply(pus_tm.crc16().unwrap(), vec.as_slice());
    }

    #[test]
@ -1369,7 +1068,7 @@ mod tests {
        assert_eq!(vec.len(), 26);
    }

-    fn verify_raw_ping_reply_no_crc(buf: &[u8]) {
+    fn verify_raw_ping_reply(crc16: u16, buf: &[u8]) {
        // Secondary header is set -> 0b0000_1001 , APID occupies last bit of first byte
        assert_eq!(buf[0], 0x09);
        // Rest of APID 0x123
@ -1390,19 +1089,12 @@ mod tests {
        assert_eq!(buf[12], 0x00);
        // Timestamp
        assert_eq!(&buf[13..20], dummy_timestamp());
-    }
-
-    fn verify_raw_ping_reply(crc16: Option<u16>, buf: &[u8]) {
-        verify_raw_ping_reply_no_crc(buf);
        let mut digest = CRC_CCITT_FALSE.digest();
        digest.update(&buf[0..20]);
        let crc16_calced = digest.finalize();
-        let crc16_read = u16::from_be_bytes([buf[20], buf[21]]);
-        assert_eq!(crc16_read, crc16_calced);
-        if let Some(crc16) = crc16 {
-            assert_eq!(((crc16 >> 8) & 0xff) as u8, buf[20]);
-            assert_eq!((crc16 & 0xff) as u8, buf[21]);
-        }
+        assert_eq!(((crc16 >> 8) & 0xff) as u8, buf[20]);
+        assert_eq!((crc16 & 0xff) as u8, buf[21]);
+        assert_eq!(crc16, crc16_calced);
    }

    fn verify_ping_reply(
@ -1429,7 +1121,7 @@ mod tests {
    }

    fn verify_ping_reply_generic(
-        tm: &(impl GenericPusTmSecondaryHeader + PusPacket),
+        tm: &(impl CcsdsPacket + GenericPusTmSecondaryHeader + PusPacket),
        has_user_data: bool,
        exp_full_len: usize,
    ) {
@ -1470,7 +1162,7 @@ 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, PusTmReader::new(&buf, timestamp.len()).unwrap());
+        assert_eq!(pus_tm, PusTmReader::new(&buf, timestamp.len()).unwrap().0);
    }

    #[test]
@ -1490,8 +1182,9 @@ mod tests {
        assert!(!writer.set_apid(MAX_SEQ_COUNT + 1));
        writer.finish();
        // This performs all necessary checks, including the CRC check.
-        let tm_read_back = PusTmReader::new(&buf, 7).expect("Re-creating PUS TM failed");
-        assert_eq!(tm_read_back.total_len(), tm_size);
+        let (tm_read_back, tm_size_read_back) =
+            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);
        assert_eq!(tm_read_back.seq_count(), MAX_SEQ_COUNT);
@ -1539,7 +1232,7 @@ mod tests {
        assert_eq!(writer.sec_header_without_timestamp().msg_counter(), 100);
        assert_eq!(writer.user_data(), DUMMY_DATA);
        // Need to check crc16 before finish, because finish will update the CRC.
-        let crc16 = writer.opt_crc16();
+        let crc16 = writer.crc16();
        assert!(crc16.is_some());
        assert_eq!(crc16.unwrap(), crc16_raw);
        writer.finish();
@ -1557,8 +1250,8 @@ mod tests {
        let pus_tm = base_ping_reply_full_ctor(timestamp);
        let mut buf = [0; 32];
        pus_tm.write_to_bytes(&mut buf).unwrap();
-        let tm_0 = PusTmReader::new(&buf, timestamp.len()).unwrap();
-        let tm_1 = PusTmReader::new(&buf, timestamp.len()).unwrap();
+        let (tm_0, _) = PusTmReader::new(&buf, timestamp.len()).unwrap();
+        let (tm_1, _) = PusTmReader::new(&buf, timestamp.len()).unwrap();
        assert_eq!(tm_0, tm_1);
    }
    #[test]
@ -1630,7 +1323,7 @@ mod tests {
            PusTmCreator::new_simple(sph, 17, 2, &time_provider, &mut stamp_buf, &[], true)
                .unwrap();
        let pus_tm_vec = pus_tm.to_vec().unwrap();
-        let tm_reader = PusTmReader::new(&pus_tm_vec, time_provider.len_as_bytes()).unwrap();
+        let (tm_reader, _) = PusTmReader::new(&pus_tm_vec, time_provider.len_as_bytes()).unwrap();
        let output = to_allocvec(&tm_reader).unwrap();
        let output_converted_back: PusTmReader = from_bytes(&output).unwrap();
        assert_eq!(output_converted_back, tm_reader);
--- a/src/lib.rs
+++ b/src/lib.rs
@ -26,8 +26,8 @@
 //!
 //!  - [`std`](https://doc.rust-lang.org/std/): Enables functionality relying on the standard library.
 //!  - [`alloc`](https://doc.rust-lang.org/alloc/): Enables features which operate on containers
-//!    like [`alloc::vec::Vec`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html).
-//!    Enabled by the `std` feature.
+//!     like [`alloc::vec::Vec`](https://doc.rust-lang.org/beta/alloc/vec/struct.Vec.html).
+//!     Enabled by the `std` feature.
 //!
 //! ### Optional features
 //!
@ -61,18 +61,24 @@ extern crate alloc;
 #[cfg(any(feature = "std", test))]
 extern crate std;

-use core::{fmt::Debug, hash::Hash};
+use core::{
+    fmt::{Debug, Display, Formatter},
+    hash::Hash,
+};
+use crc::{Crc, CRC_16_IBM_3740};
 use delegate::delegate;
-use zerocopy::{FromBytes, IntoBytes};
+
+#[cfg(feature = "std")]
+use std::error::Error;

 #[cfg(feature = "serde")]
 use serde::{Deserialize, Serialize};

 pub mod cfdp;
-pub mod crc;
 pub mod ecss;
 pub mod seq_count;
 pub mod time;
+pub mod uslp;
 pub mod util;

 mod private {
@ -81,28 +87,62 @@ mod private {

 pub const CCSDS_HEADER_LEN: usize = core::mem::size_of::<crate::zc::SpHeader>();

+/// CRC algorithm used by the PUS standard, the CCSDS TC standard and the CFDP standard.
+pub const CRC_CCITT_FALSE: Crc<u16> = Crc::<u16>::new(&CRC_16_IBM_3740);
+
 pub const MAX_APID: u16 = 2u16.pow(11) - 1;
 pub const MAX_SEQ_COUNT: u16 = 2u16.pow(14) - 1;

 /// Generic error type when converting to and from raw byte slices.
-#[derive(Debug, Copy, Clone, PartialEq, Eq, thiserror::Error)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum ByteConversionError {
    /// The passed slice is too small. Returns the passed slice length and expected minimum size
-    #[error("target slice with size {found} is too small, expected size of at least {expected}")]
-    ToSliceTooSmall { found: usize, expected: usize },
+    ToSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
    /// The provider buffer is too small. Returns the passed slice length and expected minimum size
-    #[error("source slice with size {found} too small, expected at least {expected} bytes")]
-    FromSliceTooSmall { found: usize, expected: usize },
+    FromSliceTooSmall {
+        found: usize,
+        expected: usize,
+    },
    /// The [zerocopy] library failed to write to bytes
-    #[error("zerocopy serialization error")]
    ZeroCopyToError,
-    /// The [zerocopy] library failed to read from bytes
-    #[error("zerocopy deserialization error")]
    ZeroCopyFromError,
 }

+impl Display for ByteConversionError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            ByteConversionError::ToSliceTooSmall { found, expected } => {
+                write!(
+                    f,
+                    "target slice with size {} is too small, expected size of at least {}",
+                    found, expected
+                )
+            }
+            ByteConversionError::FromSliceTooSmall { found, expected } => {
+                write!(
+                    f,
+                    "source slice with size {} too small, expected at least {} bytes",
+                    found, expected
+                )
+            }
+            ByteConversionError::ZeroCopyToError => {
+                write!(f, "zerocopy serialization error")
+            }
+            ByteConversionError::ZeroCopyFromError => {
+                write!(f, "zerocopy deserialization error")
+            }
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for ByteConversionError {}
+
 /// CCSDS packet type enumeration.
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@ -449,9 +489,9 @@ pub trait CcsdsPrimaryHeader {
 /// # Arguments
 ///
 /// * `version` - CCSDS version field, occupies the first 3 bits of the raw header. Will generally
-///   be set to 0b000 in all constructors provided by this crate.
+///    be set to 0b000 in all constructors provided by this crate.
 /// * `packet_id` - Packet Identifier, which can also be used as a start marker. Occupies the last
-///   13 bits of the first two bytes of the raw header
+///    13 bits of the first two bytes of the raw header
 /// * `psc` - Packet Sequence Control, occupies the third and fourth byte of the raw header
 /// * `data_len` - Data length field occupies the fifth and the sixth byte of the raw header
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
@ -694,8 +734,8 @@ impl SpHeader {
                expected: CCSDS_HEADER_LEN,
            });
        }
-        let zc_header = zc::SpHeader::read_from_bytes(&buf[0..CCSDS_HEADER_LEN])
-            .map_err(|_| ByteConversionError::ZeroCopyFromError)?;
+        let zc_header = zc::SpHeader::from_bytes(&buf[0..CCSDS_HEADER_LEN])
+            .ok_or(ByteConversionError::ZeroCopyFromError)?;
        Ok((Self::from(zc_header), &buf[CCSDS_HEADER_LEN..]))
    }

@ -713,8 +753,8 @@ impl SpHeader {
        }
        let zc_header: zc::SpHeader = zc::SpHeader::from(*self);
        zc_header
-            .write_to(&mut buf[0..CCSDS_HEADER_LEN])
-            .map_err(|_| ByteConversionError::ZeroCopyToError)?;
+            .to_bytes(&mut buf[0..CCSDS_HEADER_LEN])
+            .ok_or(ByteConversionError::ZeroCopyToError)?;
        Ok(&mut buf[CCSDS_HEADER_LEN..])
    }

@ -776,9 +816,9 @@ sph_from_other!(SpHeader, crate::zc::SpHeader);
 pub mod zc {
    use crate::{CcsdsPacket, CcsdsPrimaryHeader, PacketId, PacketSequenceCtrl, VERSION_MASK};
    use zerocopy::byteorder::NetworkEndian;
-    use zerocopy::{FromBytes, Immutable, IntoBytes, Unaligned, U16};
+    use zerocopy::{AsBytes, FromBytes, FromZeroes, Unaligned, U16};

-    #[derive(FromBytes, IntoBytes, Immutable, Unaligned, Debug)]
+    #[derive(FromBytes, FromZeroes, AsBytes, Unaligned, Debug)]
    #[repr(C)]
    pub struct SpHeader {
        version_packet_id: U16<NetworkEndian>,
@ -803,6 +843,14 @@ pub mod zc {
                data_len: U16::from(data_len),
            }
        }
+
+        pub fn from_bytes(slice: &[u8]) -> Option<Self> {
+            SpHeader::read_from(slice)
+        }
+
+        pub fn to_bytes(&self, slice: &mut [u8]) -> Option<()> {
+            self.write_to(slice)
+        }
    }

    impl CcsdsPacket for SpHeader {
@ -871,7 +919,6 @@ pub(crate) mod tests {
    use postcard::{from_bytes, to_allocvec};
    #[cfg(feature = "serde")]
    use serde::{de::DeserializeOwned, Serialize};
-    use zerocopy::FromBytes;

    const CONST_SP: SpHeader = SpHeader::new(
        PacketId::new_for_tc(true, 0x36),
@ -1151,7 +1198,7 @@ pub(crate) mod tests {

    #[test]
    fn test_zc_sph() {
-        use zerocopy::IntoBytes;
+        use zerocopy::AsBytes;

        let sp_header = SpHeader::new_for_unseg_tc_checked(0x7FF, pow(2, 14) - 1, 0)
            .expect("Error creating SP header");
@ -1171,7 +1218,7 @@ pub(crate) mod tests {
        assert_eq!(slice[5], 0x00);

        let mut slice = [0; 6];
-        sp_header_zc.write_to(slice.as_mut_slice()).unwrap();
+        sp_header_zc.write_to(slice.as_mut_slice());
        assert_eq!(slice.len(), 6);
        assert_eq!(slice[0], 0x17);
        assert_eq!(slice[1], 0xFF);
@ -1182,7 +1229,7 @@ pub(crate) mod tests {

        let mut test_vec = vec![0_u8; 6];
        let slice = test_vec.as_mut_slice();
-        sp_header_zc.write_to(slice).unwrap();
+        sp_header_zc.write_to(slice);
        let slice = test_vec.as_slice();
        assert_eq!(slice.len(), 6);
        assert_eq!(slice[0], 0x17);
@ -1192,8 +1239,8 @@ pub(crate) mod tests {
        assert_eq!(slice[4], 0x00);
        assert_eq!(slice[5], 0x00);

-        let sp_header = zc::SpHeader::read_from_bytes(slice);
-        assert!(sp_header.is_ok());
+        let sp_header = zc::SpHeader::from_bytes(slice);
+        assert!(sp_header.is_some());
        let sp_header = sp_header.unwrap();
        assert_eq!(sp_header.ccsds_version(), 0b000);
        assert_eq!(sp_header.packet_id_raw(), 0x17FF);
--- a/src/time/cds.rs
+++ b/src/time/cds.rs
@ -7,13 +7,17 @@
 use crate::private::Sealed;
 use crate::ByteConversionError;
 use core::cmp::Ordering;
-use core::fmt::Debug;
+use core::fmt::{Debug, Display, Formatter};
 use core::ops::{Add, AddAssign};
 use core::time::Duration;

+use delegate::delegate;
+
 #[cfg(feature = "std")]
 use super::StdTimestampError;
 #[cfg(feature = "std")]
+use std::error::Error;
+#[cfg(feature = "std")]
 use std::time::{SystemTime, SystemTimeError};

 #[cfg(feature = "chrono")]
@ -89,19 +93,49 @@ pub enum SubmillisPrecision {
    Reserved = 0b11,
 }

-#[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub enum CdsError {
    /// CCSDS days value exceeds maximum allowed size or is negative
-    #[error("invalid ccsds days {0}")]
    InvalidCcsdsDays(i64),
    /// There are distinct constructors depending on the days field width detected in the preamble
    /// field. This error will be returned if there is a missmatch.
-    #[error("wrong constructor for length of day {0:?} detected in preamble")]
    InvalidCtorForDaysOfLenInPreamble(LengthOfDaySegment),
-    #[error("date before CCSDS epoch: {0}")]
-    DateBeforeCcsdsEpoch(#[from] DateBeforeCcsdsEpochError),
+    DateBeforeCcsdsEpoch(DateBeforeCcsdsEpochError),
+}
+
+impl Display for CdsError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        match self {
+            CdsError::InvalidCcsdsDays(days) => {
+                write!(f, "invalid ccsds days {days}")
+            }
+            CdsError::InvalidCtorForDaysOfLenInPreamble(length_of_day) => {
+                write!(
+                    f,
+                    "wrong constructor for length of day {length_of_day:?} detected in preamble",
+                )
+            }
+            CdsError::DateBeforeCcsdsEpoch(e) => write!(f, "date before CCSDS epoch: {e}"),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for CdsError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            CdsError::DateBeforeCcsdsEpoch(e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl From<DateBeforeCcsdsEpochError> for CdsError {
+    fn from(value: DateBeforeCcsdsEpochError) -> Self {
+        Self::DateBeforeCcsdsEpoch(value)
+    }
 }

 pub fn length_of_day_segment_from_pfield(pfield: u8) -> LengthOfDaySegment {
@ -266,23 +300,20 @@ impl CdsConverter for ConversionFromUnix {
        self.unix_days_seconds
    }
 }
-
 /// Helper struct which generates fields for the CDS time provider from a datetime.
-#[cfg(feature = "chrono")]
 struct ConversionFromChronoDatetime {
    unix_conversion: ConversionFromUnix,
    submillis_prec: SubmillisPrecision,
    submillis: u32,
 }

-#[cfg(feature = "chrono")]
 impl CdsCommon for ConversionFromChronoDatetime {
    #[inline]
    fn submillis_precision(&self) -> SubmillisPrecision {
        self.submillis_prec
    }

-    delegate::delegate! {
+    delegate! {
        to self.unix_conversion {
            #[inline]
            fn ms_of_day(&self) -> u32;
@ -297,9 +328,8 @@ impl CdsCommon for ConversionFromChronoDatetime {
    }
 }

-#[cfg(feature = "chrono")]
 impl CdsConverter for ConversionFromChronoDatetime {
-    delegate::delegate! {to self.unix_conversion {
+    delegate! {to self.unix_conversion {
        #[inline]
        fn unix_days_seconds(&self) -> i64;
    }}
@ -336,6 +366,7 @@ impl ConversionFromChronoDatetime {
        Self::new_generic(dt, SubmillisPrecision::Picoseconds)
    }

+    #[cfg(feature = "chrono")]
    fn new_generic(
        dt: &chrono::DateTime<chrono::Utc>,
        prec: SubmillisPrecision,
@ -417,7 +448,7 @@ impl CdsCommon for ConversionFromNow {
    fn submillis_precision(&self) -> SubmillisPrecision {
        self.submillis_prec
    }
-    delegate::delegate! {
+    delegate! {
        to self.unix_conversion {
            fn ms_of_day(&self) -> u32;
            fn ccsds_days_as_u32(&self) -> u32;
@ -431,7 +462,7 @@ impl CdsCommon for ConversionFromNow {

 #[cfg(feature = "std")]
 impl CdsConverter for ConversionFromNow {
-    delegate::delegate! {to self.unix_conversion { fn unix_days_seconds(&self) -> i64; }}
+    delegate! {to self.unix_conversion { fn unix_days_seconds(&self) -> i64; }}
 }

 #[cfg(feature = "alloc")]
@ -569,7 +600,7 @@ impl<ProvidesDaysLen: ProvidesDaysLength> CdsTime<ProvidesDaysLen> {
            ));
        }
        let pfield = buf[0];
-        match CcsdsTimeCode::try_from((pfield >> 4) & 0b111) {
+        match CcsdsTimeCode::try_from(pfield >> 4 & 0b111) {
            Ok(cds_type) => match cds_type {
                CcsdsTimeCode::Cds => (),
                _ => {
@ -582,7 +613,7 @@ impl<ProvidesDaysLen: ProvidesDaysLength> CdsTime<ProvidesDaysLen> {
            _ => {
                return Err(TimestampError::InvalidTimeCode {
                    expected: CcsdsTimeCode::Cds,
-                    found: (pfield >> 4) & 0b111,
+                    found: pfield >> 4 & 0b111,
                });
            }
        };
--- a/src/time/mod.rs
+++ b/src/time/mod.rs
@ -63,12 +63,20 @@ pub fn ccsds_time_code_from_p_field(pfield: u8) -> Result<CcsdsTimeCode, u8> {
    CcsdsTimeCode::try_from(raw_bits).map_err(|_| raw_bits)
 }

-#[derive(Debug, PartialEq, Eq, Copy, Clone, thiserror::Error)]
+#[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
-#[error("date before ccsds epoch: {0:?}")]
 pub struct DateBeforeCcsdsEpochError(UnixTime);

+impl Display for DateBeforeCcsdsEpochError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
+        write!(f, "date before ccsds epoch: {:?}", self.0)
+    }
+}
+
+#[cfg(feature = "std")]
+impl Error for DateBeforeCcsdsEpochError {}
+
 #[derive(Debug, PartialEq, Eq, Copy, Clone)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
--- a/src/uslp/mod.rs
+++ b/src/uslp/mod.rs
@ -0,0 +1,685 @@
+/// # Support of the CCSDS Unified Space Data Link Protocol (USLP)
+use crate::{ByteConversionError, CRC_CCITT_FALSE};
+
+/// Only this version is supported by the library
+pub const USLP_VERSION_NUMBER: u8 = 0b1100;
+
+/// Identifies the association of the data contained in the transfer frame.
+#[derive(
+    Debug, Copy, Clone, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive,
+)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum SourceOrDestField {
+    /// SCID refers to the source of the transfer frame.
+    Source = 0,
+    /// SCID refers to the destination of the transfer frame.
+    Dest = 1,
+}
+
+#[derive(
+    Debug, Copy, Clone, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive,
+)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum BypassSequenceControlFlag {
+    /// Acceptance of this frame on the receiving end is subject to normal frame acceptance
+    /// checks of FARM.
+    SequenceControlledQoS = 0,
+    /// Frame Acceptance Checks of FARM by the receiving end shall be bypassed.
+    ExpeditedQoS = 1,
+}
+
+#[derive(
+    Debug, Copy, Clone, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive,
+)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum ProtocolControlCommandFlag {
+    TfdfContainsUserData = 0,
+    TfdfContainsProtocolInfo = 1,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum UslpError {
+    ByteConversion(ByteConversionError),
+    HeaderIsTruncated,
+    InvalidProtocolId(u8),
+    InvalidConstructionRule(u8),
+    InvalidVersionNumber(u8),
+    InvalidVcid(u8),
+    InvalidMapId(u8),
+    ChecksumFailure(u16),
+}
+
+impl From<ByteConversionError> for UslpError {
+    fn from(value: ByteConversionError) -> Self {
+        Self::ByteConversion(value)
+    }
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct InvalidValueForLen {
+    value: u64,
+    len: u8,
+}
+
+#[derive(Debug, Copy, Clone, Eq)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub struct PrimaryHeader {
+    pub spacecraft_id: u16,
+    pub source_or_dest_field: SourceOrDestField,
+    pub vc_id: u8,
+    pub map_id: u8,
+    frame_len_field: u16,
+    pub sequence_control_flag: BypassSequenceControlFlag,
+    pub protocol_control_command_flag: ProtocolControlCommandFlag,
+    pub ocf_flag: bool,
+    vc_frame_count_len: u8,
+    vc_frame_count: u64,
+}
+
+impl PrimaryHeader {
+    pub fn new(
+        spacecraft_id: u16,
+        source_or_dest_field: SourceOrDestField,
+        vc_id: u8,
+        map_id: u8,
+        frame_len: u16,
+    ) -> Result<Self, UslpError> {
+        if vc_id > 0b111111 {
+            return Err(UslpError::InvalidVcid(vc_id));
+        }
+        if map_id > 0b1111 {
+            return Err(UslpError::InvalidMapId(map_id));
+        }
+        Ok(Self {
+            spacecraft_id,
+            source_or_dest_field,
+            vc_id,
+            map_id,
+            frame_len_field: frame_len.saturating_sub(1),
+            sequence_control_flag: BypassSequenceControlFlag::SequenceControlledQoS,
+            protocol_control_command_flag: ProtocolControlCommandFlag::TfdfContainsUserData,
+            ocf_flag: false,
+            vc_frame_count_len: 0,
+            vc_frame_count: 0,
+        })
+    }
+
+    pub fn set_vc_frame_count(
+        &mut self,
+        count_len: u8,
+        count: u64,
+    ) -> Result<(), InvalidValueForLen> {
+        if count > 2_u64.pow(count_len as u32 * 8) - 1 {
+            return Err(InvalidValueForLen {
+                value: count,
+                len: count_len,
+            });
+        }
+        self.vc_frame_count_len = count_len;
+        self.vc_frame_count = count;
+        Ok(())
+    }
+
+    #[inline(always)]
+    pub fn vc_frame_count(&self) -> u64 {
+        self.vc_frame_count
+    }
+
+    #[inline(always)]
+    pub fn vc_frame_count_len(&self) -> u8 {
+        self.vc_frame_count_len
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<Self, UslpError> {
+        if buf.len() < 4 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 4,
+            }
+            .into());
+        }
+        // Can only deal with regular frames for now.
+        if (buf[3] & 0b1) == 1 {
+            return Err(UslpError::HeaderIsTruncated);
+        }
+        // We could check this above, but this is a better error for the case where the user
+        // tries to read a truncated frame.
+        if buf.len() < 7 {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 7,
+            }
+            .into());
+        }
+        let version_number = (buf[0] >> 4) & 0b1111;
+        if version_number != USLP_VERSION_NUMBER {
+            return Err(UslpError::InvalidVersionNumber(version_number));
+        }
+        let source_or_dest_field = match (buf[2] >> 3) & 1 {
+            0 => SourceOrDestField::Source,
+            1 => SourceOrDestField::Dest,
+            _ => unreachable!(),
+        };
+        let vc_frame_count_len = buf[6] & 0b111;
+        if buf.len() < 7 + vc_frame_count_len as usize {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: buf.len(),
+                expected: 7 + vc_frame_count_len as usize,
+            }
+            .into());
+        }
+        let vc_frame_count = match vc_frame_count_len {
+            1 => buf[7] as u64,
+            2 => u16::from_be_bytes(buf[7..9].try_into().unwrap()) as u64,
+            4 => u32::from_be_bytes(buf[7..11].try_into().unwrap()) as u64,
+            len => {
+                let mut vcf_count = 0u64;
+                let mut end = len;
+                for byte in buf[7..7 + len as usize].iter() {
+                    vcf_count |= (*byte as u64) << ((end - 1) * 8);
+                    end -= 1;
+                }
+                vcf_count
+            }
+        };
+        Ok(Self {
+            spacecraft_id: (((buf[0] as u16) & 0b1111) << 12)
+                | ((buf[1] as u16) << 4)
+                | ((buf[2] as u16) >> 4) & 0b1111,
+            source_or_dest_field,
+            vc_id: ((buf[2] & 0b111) << 3) | (buf[3] >> 5) & 0b111,
+            map_id: (buf[3] >> 1) & 0b1111,
+            frame_len_field: ((buf[4] as u16) << 8) | buf[5] as u16,
+            sequence_control_flag: ((buf[6] >> 7) & 0b1).try_into().unwrap(),
+            protocol_control_command_flag: ((buf[6] >> 6) & 0b1).try_into().unwrap(),
+            ocf_flag: ((buf[6] >> 3) & 0b1) != 0,
+            vc_frame_count_len,
+            vc_frame_count,
+        })
+    }
+
+    pub fn write_to_be_bytes(&self, buf: &mut [u8]) -> Result<usize, ByteConversionError> {
+        if buf.len() < self.len_header() {
+            return Err(ByteConversionError::ToSliceTooSmall {
+                found: buf.len(),
+                expected: self.len_header(),
+            });
+        }
+        buf[0] = (USLP_VERSION_NUMBER << 4) | ((self.spacecraft_id >> 12) as u8) & 0b1111;
+        buf[1] = (self.spacecraft_id >> 4) as u8;
+        buf[2] = (((self.spacecraft_id & 0b1111) as u8) << 4)
+            | ((self.source_or_dest_field as u8) << 3)
+            | (self.vc_id >> 3) & 0b111;
+        buf[3] = ((self.vc_id & 0b111) << 5) | (self.map_id << 1);
+        buf[4..6].copy_from_slice(&self.frame_len_field.to_be_bytes());
+        buf[6] = ((self.sequence_control_flag as u8) << 7)
+            | ((self.protocol_control_command_flag as u8) << 6)
+            | ((self.ocf_flag as u8) << 3)
+            | self.vc_frame_count_len;
+        let mut packet_idx = 7;
+        for idx in (0..self.vc_frame_count_len).rev() {
+            buf[packet_idx] = ((self.vc_frame_count >> (idx * 8)) & 0xff) as u8;
+            packet_idx += 1;
+        }
+        Ok(self.len_header())
+    }
+
+    #[inline(always)]
+    pub fn set_frame_len(&mut self, frame_len: usize) {
+        // 4.1.2.7.2
+        // The field contains a length count C that equals one fewer than the total octets
+        // in the transfer frame.
+        self.frame_len_field = frame_len.saturating_sub(1) as u16;
+    }
+
+    #[inline(always)]
+    pub fn len_header(&self) -> usize {
+        7 + self.vc_frame_count_len as usize
+    }
+
+    #[inline(always)]
+    pub fn len_frame(&self) -> usize {
+        // 4.1.2.7.2
+        // The field contains a length count C that equals one fewer than the total octets
+        // in the transfer frame.
+        self.frame_len_field as usize + 1
+    }
+}
+
+/// Custom implementation which skips the check whether the VC frame count length field is equal.
+/// Only the actual VC count value is compared.
+impl PartialEq for PrimaryHeader {
+    fn eq(&self, other: &Self) -> bool {
+        self.spacecraft_id == other.spacecraft_id
+            && self.source_or_dest_field == other.source_or_dest_field
+            && self.vc_id == other.vc_id
+            && self.map_id == other.map_id
+            && self.frame_len_field == other.frame_len_field
+            && self.sequence_control_flag == other.sequence_control_flag
+            && self.protocol_control_command_flag == other.protocol_control_command_flag
+            && self.ocf_flag == other.ocf_flag
+            && self.vc_frame_count == other.vc_frame_count
+    }
+}
+
+#[derive(
+    Debug, Copy, Clone, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive,
+)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+#[non_exhaustive]
+pub enum UslpProtocolId {
+    SpacePacketsOrEncapsulation = 0b00000,
+    /// COP-1 control commands within the TFDZ.
+    Cop1ControlCommands = 0b00001,
+    /// COP-P control commands within the TFDZ.
+    CopPControlCommands = 0b00010,
+    /// SDLS control commands within the TFDZ.
+    Sdls = 0b00011,
+    UserDefinedOctetStream = 0b00100,
+    /// Proximity-1 Supervisory Protocol Data Units (SPDUs) within the TFDZ.
+    Spdu = 0b00111,
+    /// Entire fixed-length TFDZ contains idle data.
+    Idle = 0b11111,
+}
+
+#[derive(
+    Debug, Copy, Clone, PartialEq, Eq, num_enum::TryFromPrimitive, num_enum::IntoPrimitive,
+)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+#[repr(u8)]
+pub enum ConstructionRule {
+    /// Indicated fixed-length TFDZ whose contents are CCSDS packets concatenated together, which
+    /// span transfer frame boundaries. The First Header Pointer (FHP) is required for packet
+    /// extraction.
+    PacketSpanningMultipleFrames = 0b000,
+    StartOfMapaSduOrVcaSdu = 0b001,
+    ContinuingPortionOfMapaSdu = 0b010,
+    OctetStream = 0b011,
+    StartingSegment = 0b100,
+    ContinuingSegment = 0b101,
+    LastSegment = 0b110,
+    NoSegmentation = 0b111,
+}
+
+impl ConstructionRule {
+    pub const fn applicable_to_fixed_len_tfdz(&self) -> bool {
+        match self {
+            ConstructionRule::PacketSpanningMultipleFrames => true,
+            ConstructionRule::StartOfMapaSduOrVcaSdu => true,
+            ConstructionRule::ContinuingPortionOfMapaSdu => true,
+            ConstructionRule::OctetStream => false,
+            ConstructionRule::StartingSegment => false,
+            ConstructionRule::ContinuingSegment => false,
+            ConstructionRule::LastSegment => false,
+            ConstructionRule::NoSegmentation => false,
+        }
+    }
+}
+
+pub struct TransferFrameDataFieldHeader {
+    /// Construction rule for the TFDZ.
+    construction_rule: ConstructionRule,
+    uslp_protocol_id: UslpProtocolId,
+    /// First header or last valid octet pointer. Only present if the constuction rule indicated
+    /// a fixed-length TFDZ.
+    fhp_or_lvo: Option<u16>,
+}
+
+impl TransferFrameDataFieldHeader {
+    pub fn len_header(&self) -> usize {
+        if self.construction_rule.applicable_to_fixed_len_tfdz() {
+            3
+        } else {
+            1
+        }
+    }
+
+    pub fn construction_rule(&self) -> ConstructionRule {
+        self.construction_rule
+    }
+
+    pub fn uslp_protocol_id(&self) -> UslpProtocolId {
+        self.uslp_protocol_id
+    }
+
+    pub fn fhp_or_lvo(&self) -> Option<u16> {
+        self.fhp_or_lvo
+    }
+
+    pub fn from_bytes(buf: &[u8]) -> Result<Self, UslpError> {
+        if buf.is_empty() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                found: 0,
+                expected: 1,
+            }
+            .into());
+        }
+        let construction_rule = ConstructionRule::try_from((buf[0] >> 5) & 0b111)
+            .map_err(|e| UslpError::InvalidConstructionRule(e.number))?;
+        let mut fhp_or_lvo = None;
+        if construction_rule.applicable_to_fixed_len_tfdz() {
+            if buf.len() < 3 {
+                return Err(ByteConversionError::FromSliceTooSmall {
+                    found: buf.len(),
+                    expected: 3,
+                }
+                .into());
+            }
+            fhp_or_lvo = Some(u16::from_be_bytes(buf[1..3].try_into().unwrap()));
+        }
+        Ok(Self {
+            construction_rule,
+            uslp_protocol_id: UslpProtocolId::try_from(buf[0] & 0b11111)
+                .map_err(|e| UslpError::InvalidProtocolId(e.number))?,
+            fhp_or_lvo,
+        })
+    }
+}
+
+/// Simple USLP transfer frame reader.
+///
+/// Currently, only insert zone lengths of 0 are supported.
+pub struct TransferFrameReader<'buf> {
+    primary_header: PrimaryHeader,
+    data_field_header: TransferFrameDataFieldHeader,
+    data: &'buf [u8],
+    operational_control_field: Option<u32>,
+}
+
+impl<'buf> TransferFrameReader<'buf> {
+    /// This function assumes an insert zone length of 0.
+    pub fn from_bytes(
+        buf: &'buf [u8],
+        has_fecf: bool,
+    ) -> Result<TransferFrameReader<'buf>, UslpError> {
+        let primary_header = PrimaryHeader::from_bytes(buf)?;
+        if primary_header.len_frame() > buf.len() {
+            return Err(ByteConversionError::FromSliceTooSmall {
+                expected: primary_header.len_frame(),
+                found: buf.len(),
+            }
+            .into());
+        }
+        let data_field_header =
+            TransferFrameDataFieldHeader::from_bytes(&buf[primary_header.len_header()..])?;
+        let data_idx = primary_header.len_header() + data_field_header.len_header();
+        let frame_len = primary_header.len_frame();
+        let mut operational_control_field = None;
+        let mut data_len = frame_len - data_idx;
+        if has_fecf {
+            data_len -= 2;
+        }
+        if primary_header.ocf_flag {
+            data_len -= 4;
+            operational_control_field = Some(u32::from_be_bytes(
+                buf[data_idx + data_len..data_idx + data_len + 4]
+                    .try_into()
+                    .unwrap(),
+            ));
+        }
+        let data_end = data_idx + data_len;
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&buf[0..frame_len]);
+        if digest.finalize() != 0 {
+            return Err(UslpError::ChecksumFailure(u16::from_be_bytes(
+                buf[frame_len - 2..frame_len].try_into().unwrap(),
+            )));
+        }
+        Ok(Self {
+            primary_header,
+            data_field_header,
+            data: buf[data_idx..data_end].try_into().unwrap(),
+            operational_control_field,
+        })
+    }
+
+    pub fn len_frame(&self) -> usize {
+        self.primary_header.len_frame()
+    }
+
+    pub fn primary_header(&self) -> &PrimaryHeader {
+        &self.primary_header
+    }
+
+    pub fn data_field_header(&self) -> &TransferFrameDataFieldHeader {
+        &self.data_field_header
+    }
+
+    pub fn data(&self) -> &'buf [u8] {
+        self.data
+    }
+
+    pub fn operational_control_field(&self) -> &Option<u32> {
+        &self.operational_control_field
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::println;
+
+    use super::*;
+
+    fn common_basic_check(buf: &[u8]) {
+        assert_eq!(buf[0] >> 4, USLP_VERSION_NUMBER);
+        // First four bits SCID.
+        assert_eq!(buf[0] & 0b1111, 0b1010);
+        // Next eight bits SCID.
+        assert_eq!(buf[1], 0b01011100);
+        // Last four bits SCID.
+        assert_eq!(buf[2] >> 4, 0b0011);
+        assert_eq!((buf[2] >> 3) & 0b1, SourceOrDestField::Dest as u8);
+        // First three bits VCID.
+        assert_eq!(buf[2] & 0b111, 0b110);
+        // Last three bits VCID.
+        assert_eq!(buf[3] >> 5, 0b101);
+        // MAP ID
+        assert_eq!((buf[3] >> 1) & 0b1111, 0b1010);
+        // End of primary header flag
+        assert_eq!(buf[3] & 0b1, 0);
+        assert_eq!(u16::from_be_bytes(buf[4..6].try_into().unwrap()), 0x2345);
+    }
+    #[test]
+    fn test_basic_0() {
+        let mut buf: [u8; 8] = [0; 8];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        // Virtual channel count 0.
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 7);
+        common_basic_check(&buf);
+        // Bypass / Sequence Control Flag.
+        assert_eq!(
+            (buf[6] >> 7) & 0b1,
+            BypassSequenceControlFlag::SequenceControlledQoS as u8
+        );
+        // Protocol Control Command Flag.
+        assert_eq!(
+            (buf[6] >> 6) & 0b1,
+            ProtocolControlCommandFlag::TfdfContainsUserData as u8
+        );
+        // OCF flag.
+        assert_eq!((buf[6] >> 3) & 0b1, false as u8);
+        // VCF count length.
+        assert_eq!(buf[6] & 0b111, 0);
+    }
+
+    #[test]
+    fn test_basic_1() {
+        let mut buf: [u8; 16] = [0; 16];
+        // Should be all zeros after writing.
+        buf[6] = 0xff;
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.sequence_control_flag = BypassSequenceControlFlag::ExpeditedQoS;
+        primary_header.protocol_control_command_flag =
+            ProtocolControlCommandFlag::TfdfContainsProtocolInfo;
+        primary_header.ocf_flag = true;
+        primary_header.set_vc_frame_count(4, 0x12345678).unwrap();
+        // Virtual channel count 4.
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 11);
+        common_basic_check(&buf);
+        // Bypass / Sequence Control Flag.
+        assert_eq!(
+            (buf[6] >> 7) & 0b1,
+            BypassSequenceControlFlag::ExpeditedQoS as u8
+        );
+        // Protocol Control Command Flag.
+        assert_eq!(
+            (buf[6] >> 6) & 0b1,
+            ProtocolControlCommandFlag::TfdfContainsProtocolInfo as u8
+        );
+        // OCF flag.
+        assert_eq!((buf[6] >> 3) & 0b1, true as u8);
+        // VCF count length.
+        assert_eq!(buf[6] & 0b111, 4);
+        assert_eq!(
+            u32::from_be_bytes(buf[7..11].try_into().unwrap()),
+            0x12345678
+        );
+    }
+
+    #[test]
+    fn test_reading_0() {
+        let mut buf: [u8; 8] = [0; 8];
+        let primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 7);
+        let parsed_header = PrimaryHeader::from_bytes(&buf).unwrap();
+        assert_eq!(parsed_header, primary_header);
+    }
+
+    #[test]
+    fn test_reading_1() {
+        let mut buf: [u8; 16] = [0; 16];
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        primary_header.sequence_control_flag = BypassSequenceControlFlag::ExpeditedQoS;
+        primary_header.protocol_control_command_flag =
+            ProtocolControlCommandFlag::TfdfContainsProtocolInfo;
+        primary_header.ocf_flag = true;
+        primary_header.set_vc_frame_count(4, 0x12345678).unwrap();
+        assert_eq!(primary_header.write_to_be_bytes(&mut buf).unwrap(), 11);
+        let parsed_header = PrimaryHeader::from_bytes(&buf).unwrap();
+        assert_eq!(parsed_header, primary_header);
+    }
+
+    #[test]
+    fn test_invalid_vcid() {
+        let error = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b1101011,
+            0b1010,
+            0x2345,
+        );
+        assert!(error.is_err());
+        let error = error.unwrap_err();
+        matches!(error, UslpError::InvalidVcid(0b1101011));
+    }
+
+    #[test]
+    fn test_invalid_mapid() {
+        let error = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b10101,
+            0x2345,
+        );
+        assert!(error.is_err());
+        let error = error.unwrap_err();
+        matches!(error, UslpError::InvalidMapId(0b10101));
+    }
+
+    #[test]
+    fn test_invalid_vc_count() {
+        let mut primary_header = PrimaryHeader::new(
+            0b10100101_11000011,
+            SourceOrDestField::Dest,
+            0b110101,
+            0b1010,
+            0x2345,
+        )
+        .unwrap();
+        matches!(
+            primary_header.set_vc_frame_count(0, 1).unwrap_err(),
+            InvalidValueForLen { value: 1, len: 0 }
+        );
+        matches!(
+            primary_header.set_vc_frame_count(1, 256).unwrap_err(),
+            InvalidValueForLen { value: 256, len: 1 }
+        );
+    }
+
+    #[test]
+    fn test_frame_parser() {
+        let mut buf: [u8; 32] = [0; 32];
+        // Build a variable frame manually.
+        let mut primary_header =
+            PrimaryHeader::new(0x01, SourceOrDestField::Dest, 0b110101, 0b1010, 0).unwrap();
+        let header_len = primary_header.len_header();
+        buf[header_len] = ((ConstructionRule::NoSegmentation as u8) << 5)
+            | (UslpProtocolId::UserDefinedOctetStream as u8) & 0b11111;
+        buf[header_len + 1] = 0x42;
+        // 1 byte TFDH, 1 byte data, 2 bytes CRC.
+        primary_header.set_frame_len(header_len + 4);
+        primary_header.write_to_be_bytes(&mut buf).unwrap();
+        // Calculate and write CRC16.
+        let mut digest = CRC_CCITT_FALSE.digest();
+        digest.update(&buf[0..header_len + 2]);
+        buf[header_len + 2..header_len + 4].copy_from_slice(&digest.finalize().to_be_bytes());
+        println!("Buffer: {:x?}", buf);
+        // Now parse the frame.
+        let frame = TransferFrameReader::from_bytes(&buf, true).unwrap();
+        assert_eq!(frame.data().len(), 1);
+        assert_eq!(frame.data()[0], 0x42);
+        assert_eq!(
+            frame.data_field_header().uslp_protocol_id,
+            UslpProtocolId::UserDefinedOctetStream
+        );
+        assert_eq!(
+            frame.data_field_header().construction_rule,
+            ConstructionRule::NoSegmentation
+        );
+        assert!(frame.data_field_header().fhp_or_lvo().is_none());
+        assert_eq!(frame.len_frame(), 11);
+    }
+}
Author	SHA1	Message	Date
Robin Mueller	35d48671fb	tested basic frame parser Some checks failed Rust/spacepackets/pipeline/head There was a failure building this commit Details	2024-10-08 16:24:16 +02:00
Robin Mueller	0a7fa4ecf0	continue USLP support All checks were successful Rust/spacepackets/pipeline/head This commit looks good Details	2024-10-08 15:34:47 +02:00
Robin Mueller	77003ccfe3	add more USLP API Some checks failed Rust/spacepackets/pipeline/head There was a failure building this commit Details	2024-10-07 17:31:11 +02:00
Robin Mueller	7d87c0fbc7	add basic USLP support Some checks failed Rust/spacepackets/pipeline/head There was a failure building this commit Details	2024-10-07 15:27:45 +02:00