Namespaces
namespace	detail
	Pre-computed COUNT encodings for values 1-33.

Classes
class	BitBuffer
	Variable-length bit buffer with static allocation. More...

class	BitReader
	Sequential bit reader for compressed data. More...

class	BitVector
	Fixed-length bit vector with compile-time size. More...

class	Ccsds124Exception
	Base exception for CCSDS 124.0-B-1 errors. More...

class	Compressor
	CCSDS 124.0-B-1 compressor with static memory allocation. More...

struct	CompressParams
	Compression parameters for a single packet. More...

class	Decompressor
	CCSDS 124.0-B-1 decompressor with static memory allocation. More...

class	InvalidArgumentException
	Exception for invalid arguments. More...

class	InvalidDataException
	Exception for invalid/corrupted data. More...

class	OverflowException
	Exception for buffer overflow. More...

class	UnderflowException
	Exception for buffer underflow. More...

Typedefs
using	word_t = std::uint32_t
	32-bit word type for bit vector storage (matches C implementation)

Enumerations
enum class	Error { Ok = 0 , InvalidArg = -1 , Overflow = -2 , Underflow = -3 , InvalidData = -4 }
	Error codes for error-code-based error handling. More...

Functions
template<std::size_t N>
Error	compress (const std::uint8_t input_data, std::size_t input_size, std::uint8_t output_buffer, std::size_t output_buffer_size, std::size_t &output_size, std::uint8_t robustness=0, int pt_limit=0, int ft_limit=0, int rt_limit=0) noexcept
	Compress multi-packet data stream.

template<std::size_t N>
Error	decompress (const std::uint8_t input_data, std::size_t input_size, std::uint8_t output_buffer, std::size_t output_buffer_size, std::size_t &output_size, std::uint8_t robustness=0) noexcept
	Decompress multi-packet data stream.

const char *	version () noexcept
	Get library version.

Error	count_decode (BitReader &reader, std::uint32_t &value) noexcept
	Counter decoding (inverse of CCSDS Section 5.2.2, Equation 9).

template<std::size_t N>
Error	rle_decode (BitReader &reader, BitVector< N > &result) noexcept
	Run-length decoding (inverse of CCSDS Section 5.2.3, Equation 10).

template<std::size_t N>
Error	bit_insert (BitReader &reader, BitVector< N > &data, const BitVector< N > &mask) noexcept
	Bit insertion (inverse of CCSDS Section 5.2.4, Equation 11).

template<std::size_t N>
Error	bit_insert_forward (BitReader &reader, BitVector< N > &data, const BitVector< N > &mask) noexcept
	Bit insertion with forward order.

template<std::size_t MaxBytes>
Error	count_encode (BitBuffer< MaxBytes > &output, std::uint32_t A) noexcept
	Counter encoding (CCSDS Section 5.2.2, Equation 9).

template<std::size_t MaxBytes, std::size_t N>
Error	rle_encode (BitBuffer< MaxBytes > &output, const BitVector< N > &input) noexcept
	Run-length encoding (CCSDS Section 5.2.3, Equation 10).

template<std::size_t MaxBytes, std::size_t N>
Error	bit_extract (BitBuffer< MaxBytes > &output, const BitVector< N > &data, const BitVector< N > &mask) noexcept
	Bit extraction in reverse order (CCSDS Section 5.2.4, Equation 11).

template<std::size_t MaxBytes, std::size_t N>
Error	bit_extract_forward (BitBuffer< MaxBytes > &output, const BitVector< N > &data, const BitVector< N > &mask) noexcept
	Bit extraction in forward order.

template<std::size_t MaxBytes, std::size_t N1, std::size_t N2>
Error	bit_extract (BitBuffer< MaxBytes > &output, const BitVector< N1 > &data, const BitVector< N2 > &mask) noexcept
	Bit extraction with different length vectors (for flexibility).

const char *	error_string (Error error) noexcept
	Get error message for error code.

template<std::size_t N>
void	update_build (BitVector< N > &build, const BitVector< N > &input, const BitVector< N > &prev_input, bool new_mask_flag, std::size_t t) noexcept
	Update build vector (CCSDS Equation 6).

template<std::size_t N>
void	update_mask (BitVector< N > &mask, const BitVector< N > &input, const BitVector< N > &prev_input, const BitVector< N > &build_prev, bool new_mask_flag) noexcept
	Update mask vector (CCSDS Equation 7).

template<std::size_t N>
void	compute_change (BitVector< N > &change, const BitVector< N > &mask, const BitVector< N > &prev_mask, std::size_t t) noexcept
	Compute change vector (CCSDS Equation 8).

Variables
constexpr int	VERSION_MAJOR = 1

constexpr int	VERSION_MINOR = 0

constexpr int	VERSION_PATCH = 0

constexpr std::size_t	MAX_PACKET_LENGTH = 65535U

constexpr std::size_t	MAX_PACKET_BYTES = (MAX_PACKET_LENGTH + 7U) / 8U

constexpr std::size_t	MAX_ROBUSTNESS = 7U

constexpr std::size_t	MAX_HISTORY = 16U

constexpr std::size_t	MAX_VT_HISTORY = 16U

constexpr std::size_t	MAX_OUTPUT_BYTES = MAX_PACKET_BYTES * 6U

constexpr std::size_t	BITS_PER_WORD = 32U

Detailed Description

This module provides a dynamically-growing bit buffer for constructing compressed output streams. Bits are appended sequentially using MSB-first ordering as required by CCSDS 124.0-B-1.

Bit Ordering

Bits are appended MSB-first within each byte:

First bit appended goes to bit position 7
Second bit goes to position 6, etc.

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

The bit reader provides stateful bit-level access to compressed packet data, reading MSB-first within each byte.

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

This module provides fixed-length bit vector operations optimized for CCSDS 124.0-B-1 compression. Uses 32-bit words with big-endian byte packing to match ESA/ESOC reference implementation.

Bit Numbering Convention (CCSDS 124.0-B-1 Section 1.6.1)

Bit 0 = MSB (transmitted first)
Bit N-1 = LSB (transmitted last)

Word Packing (Big-Endian)

Within each 32-bit word:

Bit 0 at position 31 of word 0 (most significant)
Bit 31 at position 0 of word 0

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Provides high-level compress() and decompress() functions for bulk data processing, suitable for file-level operations.

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Implements CCSDS 124.0-B-1 Section 5.3 (Encoding Step):

Compressor initialization and state management
Main compression algorithm
Output packet encoding: o_t = h_t || q_t || u_t

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

CCSDS 124.0-B-1: Robust Compression of Fixed-Length Housekeeping Data

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Implements CCSDS 124.0-B-1 decoding (inverse of Section 5.2):

Counter Decoding (COUNT) - inverse of Section 5.2.2, Equation 9
Run-Length Decoding (RLE) - inverse of Section 5.2.3, Equation 10
Bit Insertion - inverse of Section 5.2.4, Equation 11

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Implements CCSDS 124.0-B-1 decompression (inverse of Section 5.3):

Packet decompression and mask reconstruction
Full round-trip support with Compressor

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Implements CCSDS 124.0-B-1 Section 5.2 encoding schemes:

Counter Encoding (COUNT) - Section 5.2.2, Table 5-1, Equation 9
Run-Length Encoding (RLE) - Section 5.2.3, Equation 10
Bit Extraction (BE) - Section 5.2.4, Equation 11

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Implements CCSDS 124.0-B-1 Section 4 (Mask Update):

Build Vector Update (Equation 6)
Mask Vector Update (Equation 7)
Change Vector Computation (Equation 8)

Authors: Georges Labreche georg.nosp@m.es@t.nosp@m.anagr.nosp@m.aspa.nosp@m.ce.co.nosp@m.m; Claude Code (Anthropic) norep.nosp@m.ly@a.nosp@m.nthro.nosp@m.pic..nosp@m.com

See also: https://ccsds.org/Pubs/124x0b1.pdf CCSDS 124.0-B-1 Standard

Enumeration Type Documentation

◆ Error

enum class ccsds124::Error

strong

Error codes for error-code-based error handling.

Used when exceptions are disabled (CCSDS124_NO_EXCEPTIONS=1).

Enumerator
Ok	Success.
InvalidArg	Invalid argument.
Overflow	Buffer overflow.
Underflow	Buffer underflow (not enough data)
InvalidData	Invalid/corrupted data.

Definition at line 29 of file error.hpp.

Function Documentation

◆ bit_extract() [1/2]

template<std::size_t MaxBytes, std::size_t N>

Error ccsds124::bit_extract	(	BitBuffer< MaxBytes > &	output,
		const BitVector< N > &	data,
		const BitVector< N > &	mask
	)

noexcept

Bit extraction in reverse order (CCSDS Section 5.2.4, Equation 11).

BE(a, b) = a_{g_{H(b)-1}} ∥ ... ∥ a_{g₁} ∥ a_{g₀}

Template Parameters

MaxBytes	BitBuffer capacity
N	BitVector length

Parameters

output	Bit buffer to append extracted bits
data	Source data vector
mask	Mask indicating which bits to extract

Returns: Error::Ok on success

Definition at line 167 of file encoder.hpp.

References Ok.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet().

◆ bit_extract() [2/2]

template<std::size_t MaxBytes, std::size_t N1, std::size_t N2>

Error ccsds124::bit_extract	(	BitBuffer< MaxBytes > &	output,
		const BitVector< N1 > &	data,
		const BitVector< N2 > &	mask
	)

noexcept

Bit extraction with different length vectors (for flexibility).

Definition at line 286 of file encoder.hpp.

References InvalidArg.

◆ bit_extract_forward()

template<std::size_t MaxBytes, std::size_t N>

Error ccsds124::bit_extract_forward	(	BitBuffer< MaxBytes > &	output,
		const BitVector< N > &	data,
		const BitVector< N > &	mask
	)

noexcept

Bit extraction in forward order.

Used specifically for kₜ component encoding where forward order is required.

Template Parameters

MaxBytes	BitBuffer capacity
N	BitVector length

Parameters

output	Bit buffer to append extracted bits
data	Source data vector
mask	Mask indicating which bits to extract

Returns: Error::Ok on success

Definition at line 234 of file encoder.hpp.

References ccsds124::detail::extract_msb(), and Ok.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet().

◆ bit_insert()

template<std::size_t N>

Error ccsds124::bit_insert	(	BitReader &	reader,
		BitVector< N > &	data,
		const BitVector< N > &	mask
	)

noexcept

Bit insertion (inverse of CCSDS Section 5.2.4, Equation 11).

Inserts bits from reader at positions where mask has '1' bits. This is the inverse of bit_extract.

Template Parameters

N	BitVector length

Parameters

	reader	Bit reader with bits to insert
[in,out]	data	Data vector to insert bits into
	mask	Mask indicating where to insert

Returns: Error::Ok on success

Definition at line 175 of file decoder.hpp.

References ccsds124::detail::extract_lsb(), Ok, and Underflow.

Referenced by ccsds124::Decompressor< N >::decompress_packet().

◆ bit_insert_forward()

template<std::size_t N>

Error ccsds124::bit_insert_forward	(	BitReader &	reader,
		BitVector< N > &	data,
		const BitVector< N > &	mask
	)

noexcept

Bit insertion with forward order.

Inserts bits from reader at positions where mask has '1' bits, in forward order (MSB to LSB).

Template Parameters

N	BitVector length

Parameters

	reader	Bit reader with bits to insert
[in,out]	data	Data vector to insert bits into
	mask	Mask indicating where to insert

Returns: Error::Ok on success

Definition at line 227 of file decoder.hpp.

References ccsds124::detail::extract_msb(), Ok, and Underflow.

◆ compress()

template<std::size_t N>

Error ccsds124::compress	(	const std::uint8_t *	input_data,
		std::size_t	input_size,
		std::uint8_t *	output_buffer,
		std::size_t	output_buffer_size,
		std::size_t &	output_size,
		std::uint8_t	robustness = `0`,
		int	pt_limit = `0`,
		int	ft_limit = `0`,
		int	rt_limit = `0`
	)

noexcept

Compress multi-packet data stream.

Compresses input data as a sequence of fixed-size packets using CCSDS 124.0-B-1 algorithm.

Template Parameters

N	Packet length in bits

Parameters

	input_data	Input data bytes
	input_size	Input size in bytes (must be multiple of packet size)
	output_buffer	Output buffer for compressed data
	output_buffer_size	Maximum output buffer size
[out]	output_size	Actual compressed output size
	robustness	Robustness level R (0-7)
	pt_limit	New mask period (pt parameter)
	ft_limit	Send mask period (ft parameter)
	rt_limit	Uncompressed period (rt parameter)

Returns: Error::Ok on success

Definition at line 59 of file ccsds124.hpp.

References ccsds124::Compressor< N, MaxOutputBytes >::compress_packet(), ccsds124::BitVector< N >::from_bytes(), InvalidArg, ccsds124::CompressParams::min_robustness, ccsds124::CompressParams::new_mask_flag, Ok, Overflow, ccsds124::CompressParams::send_mask_flag, ccsds124::BitBuffer< MaxBytes >::to_bytes(), and ccsds124::CompressParams::uncompressed_flag.

◆ compute_change()

template<std::size_t N>

void ccsds124::compute_change	(	BitVector< N > &	change,
		const BitVector< N > &	mask,
		const BitVector< N > &	prev_mask,
		std::size_t	t
	)

noexcept

Compute change vector (CCSDS Equation 8).

The change vector tracks mask changes between iterations.

D_t = M_t XOR M_{t-1} (if t > 0)
D_t = M_t (if t = 0, assuming M_{-1} = 0)

Template Parameters

N	BitVector length

Parameters

[out]	change	Change vector D_t
[in]	mask	Current mask M_t
[in]	prev_mask	Previous mask M_{t-1}
[in]	t	Time index (0 = first packet)

Definition at line 115 of file mask.hpp.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet().

◆ count_decode()

Error ccsds124::count_decode	(	BitReader &	reader,
		std::uint32_t &	value
	)

inlinenoexcept

Counter decoding (inverse of CCSDS Section 5.2.2, Equation 9).

Decodes a COUNT-encoded value from a bit reader.

'0' → A = 1
'10' → terminator (A = 0)
'110' + 5 bits → A = value + 2
'111' + variable bits → A = value + 2

Parameters

	reader	Bit reader positioned at COUNT-encoded data
[out]	value	Decoded value (0 for terminator, 1+ for values)

Returns: Error::Ok on success, Error::Underflow if not enough bits

Definition at line 50 of file decoder.hpp.

References Ok, and Underflow.

Referenced by ccsds124::Decompressor< N >::decompress_packet(), and rle_decode().

◆ count_encode()

template<std::size_t MaxBytes>

Error ccsds124::count_encode	(	BitBuffer< MaxBytes > &	output,
		std::uint32_t	A
	)

noexcept

Counter encoding (CCSDS Section 5.2.2, Equation 9).

Encodes an integer A as a unary prefix followed by binary suffix.

A = 1 → '0'
2 ≤ A ≤ 33 → '110' ∥ BIT₅(A-2)
A ≥ 34 → '111' ∥ BIT_E(A-2)

Template Parameters

MaxBytes BitBuffer capacity

Parameters

output	Bit buffer to append encoded value
A	Value to encode (1 to 65535)

Returns: Error::Ok on success

Definition at line 71 of file encoder.hpp.

References ccsds124::detail::COUNT_BITS, ccsds124::detail::COUNT_VALUES, InvalidArg, and Ok.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet(), and rle_encode().

◆ decompress()

template<std::size_t N>

Error ccsds124::decompress	(	const std::uint8_t *	input_data,
		std::size_t	input_size,
		std::uint8_t *	output_buffer,
		std::size_t	output_buffer_size,
		std::size_t &	output_size,
		std::uint8_t	robustness = `0`
	)

noexcept

Decompress multi-packet data stream.

Decompresses CCSDS 124.0-B-1 compressed data back to original packets.

Template Parameters

N	Packet length in bits

Parameters

	input_data	Compressed input data bytes
	input_size	Compressed input size in bytes
	output_buffer	Output buffer for decompressed data
	output_buffer_size	Maximum output buffer size
[out]	output_size	Actual decompressed output size
	robustness	Robustness level R (0-7)

Returns: Error::Ok on success

Definition at line 184 of file ccsds124.hpp.

References ccsds124::BitReader::align_byte(), ccsds124::Decompressor< N >::decompress_packet(), Ok, Overflow, ccsds124::BitReader::remaining(), and ccsds124::BitVector< N >::to_bytes().

◆ error_string()

const char * ccsds124::error_string ( Error error )

inlinenoexcept

Get error message for error code.

Parameters

error Error code

Returns: Human-readable error message

Definition at line 42 of file error.hpp.

References InvalidArg, InvalidData, Ok, Overflow, and Underflow.

◆ rle_decode()

template<std::size_t N>

Error ccsds124::rle_decode	(	BitReader &	reader,
		BitVector< N > &	result
	)

noexcept

Run-length decoding (inverse of CCSDS Section 5.2.3, Equation 10).

Decodes RLE-encoded data back to a BitVector.

Template Parameters

N	BitVector length

Parameters

	reader	Bit reader positioned at RLE-encoded data
[out]	result	Decoded bit vector

Returns: Error::Ok on success

Definition at line 132 of file decoder.hpp.

References count_decode(), Ok, and Overflow.

Referenced by ccsds124::Decompressor< N >::decompress_packet().

◆ rle_encode()

template<std::size_t MaxBytes, std::size_t N>

Error ccsds124::rle_encode	(	BitBuffer< MaxBytes > &	output,
		const BitVector< N > &	input
	)

noexcept

Run-length encoding (CCSDS Section 5.2.3, Equation 10).

RLE(a) = COUNT(C₀) ∥ COUNT(C₁) ∥ ... ∥ COUNT(C_{H(a)-1}) ∥ '10'

Template Parameters

MaxBytes	BitBuffer capacity
N	BitVector length

Parameters

output	Bit buffer to append encoded runs
input	Bit vector to encode

Returns: Error::Ok on success

Definition at line 114 of file encoder.hpp.

References count_encode(), and Ok.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet().

◆ update_build()

template<std::size_t N>

void ccsds124::update_build	(	BitVector< N > &	build,
		const BitVector< N > &	input,
		const BitVector< N > &	prev_input,
		bool	new_mask_flag,
		std::size_t	t
	)

noexcept

Update build vector (CCSDS Equation 6).

The build vector accumulates XOR differences between consecutive packets to track which bits have changed.

B_t = (I_t XOR I_{t-1}) OR B_{t-1} (if t > 0 and new_mask_flag = 0)
B_t = 0 (otherwise: t=0 or new_mask_flag=1)

Template Parameters

N	BitVector length

Parameters

[in,out]	build	Updated build vector B_t
[in]	input	Current input I_t
[in]	prev_input	Previous input I_{t-1}
[in]	new_mask_flag	p_t flag (true = reset build)
[in]	t	Time index (0 = first packet)

Definition at line 53 of file mask.hpp.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet().

◆ update_mask()

template<std::size_t N>

void ccsds124::update_mask	(	BitVector< N > &	mask,
		const BitVector< N > &	input,
		const BitVector< N > &	prev_input,
		const BitVector< N > &	build_prev,
		bool	new_mask_flag
	)

noexcept

Update mask vector (CCSDS Equation 7).

The mask vector identifies unpredictable bits (1 = unpredictable).

M_t = (I_t XOR I_{t-1}) OR M_{t-1} (if new_mask_flag = 0)
M_t = (I_t XOR I_{t-1}) OR B_{t-1} (if new_mask_flag = 1)

Template Parameters

N	BitVector length

Parameters

[in,out]	mask	Updated mask vector M_t
[in]	input	Current input I_t
[in]	prev_input	Previous input I_{t-1}
[in]	build_prev	Previous build vector B_{t-1}
[in]	new_mask_flag	p_t flag (true = update from build)

Definition at line 84 of file mask.hpp.

Referenced by ccsds124::Compressor< N, MaxOutputBytes >::compress_packet().

◆ version()

const char * ccsds124::version ( )

inlinenoexcept

Get library version.

Returns: Version string

Definition at line 228 of file ccsds124.hpp.

Referenced by print_help(), and print_version().

Namespaces

Classes

Typedefs

Enumerations

Functions

Variables

Detailed Description

Enumeration Type Documentation

◆ Error

Function Documentation

◆ bit_extract() [1/2]

◆ bit_extract() [2/2]

◆ bit_extract_forward()

◆ bit_insert()

◆ bit_insert_forward()

◆ compress()

◆ compute_change()

◆ count_decode()

◆ count_encode()

◆ decompress()

◆ error_string()

◆ rle_decode()

◆ rle_encode()

◆ update_build()

◆ update_mask()

◆ version()