Bit Reader API

Sequential bit reading from compressed data. More...

Data Structures
struct	bitreader_t
	Bit reader structure for sequential reading. More...

Functions
void	bitreader_init (bitreader_t *reader, const uint8_t *data, size_t num_bits)
	Initialize bit reader.
int	bitreader_read_bit (bitreader_t *reader)
	Read a single bit.
uint32_t	bitreader_read_bits (bitreader_t *reader, size_t num_bits)
	Read multiple bits as unsigned value.
size_t	bitreader_position (const bitreader_t *reader)
	Get current bit position.
size_t	bitreader_remaining (const bitreader_t *reader)
	Get remaining bits.
void	bitreader_align_byte (bitreader_t *reader)
	Skip to next byte boundary.

Detailed Description

Sequential bit reading from compressed data.

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

Function Documentation

bitreader_align_byte()

void bitreader_align_byte

(

bitreader_t *

reader

)

Skip to next byte boundary.

Advances position to start of next byte (for padding).

Parameters

[in,out]

reader

Bit reader (position advanced)

Definition at line 158 of file decompress.c.

References bitreader_t::bit_pos.

Referenced by ccsds124_decompress().

bitreader_init()

void bitreader_init	(	bitreader_t *	reader,
		const uint8_t *	data,
		size_t	num_bits
	)

Initialize bit reader.

Parameters

[out]	reader	Reader to initialize
[in]	data	Source byte buffer
[in]	num_bits	Number of valid bits in buffer

Definition at line 88 of file decompress.c.

References bitreader_t::bit_pos, bitreader_t::data, and bitreader_t::num_bits.

Referenced by ccsds124_decompress(), ccsds124_decompress_packet_checked(), and ccsds124_discover_packet_length().

bitreader_position()

size_t bitreader_position

(

const bitreader_t *

reader

)

Get current bit position.

Parameters

[in]

reader

Bit reader

Returns

Number of bits already read

Definition at line 136 of file decompress.c.

References bitreader_t::bit_pos.

bitreader_read_bit()

int bitreader_read_bit

(

bitreader_t *

reader

)

Read a single bit.

Parameters

[in,out]

reader

Bit reader (position advanced)

Returns

Bit value (0 or 1), or -1 if no bits remaining

Definition at line 97 of file decompress.c.

References bitreader_t::bit_pos, bitreader_t::data, and bitreader_t::num_bits.

Referenced by bitreader_read_bits(), ccsds124_bit_insert(), ccsds124_count_decode(), ccsds124_decompress_packet_internal(), and ccsds124_discover_packet_length().

bitreader_read_bits()

uint32_t bitreader_read_bits	(	bitreader_t *	reader,
		size_t	num_bits
	)

Read multiple bits as unsigned value.

Reads up to 32 bits MSB-first and returns as uint32_t.

Parameters

[in,out]	reader	Bit reader (position advanced)
[in]	num_bits	Number of bits to read (1-32)

Returns

Unsigned value from bits read

Definition at line 115 of file decompress.c.

References bitreader_read_bit(), and bitreader_remaining().

Referenced by ccsds124_count_decode(), ccsds124_decompress_packet_internal(), and ccsds124_discover_packet_length().

bitreader_remaining()

size_t bitreader_remaining

(

const bitreader_t *

reader

)

Get remaining bits.

Parameters

[in]

reader

Bit reader

Returns

Number of bits remaining to read

Definition at line 147 of file decompress.c.

References bitreader_t::bit_pos, and bitreader_t::num_bits.

Referenced by bitreader_read_bits(), ccsds124_bit_insert(), ccsds124_count_decode(), ccsds124_decompress(), ccsds124_decompress_packet_checked(), ccsds124_decompress_packet_internal(), and ccsds124_discover_packet_length().