libavutil/crc.h File Reference

#include <stdint.h>
#include <sys/types.h>

Go to the source code of this file.

Typedefs
typedef uint32_t	AVCRC
Enumerations
enum	AVCRCId {   AV_CRC_8_ATM, AV_CRC_16_ANSI, AV_CRC_16_CCITT, AV_CRC_32_IEEE,   AV_CRC_32_IEEE_LE, AV_CRC_MAX }
Functions
int	av_crc_init (AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
	Inits a crc table.
const AVCRC *	av_crc_get_table (AVCRCId crc_id)
	Get an initialized standard CRC table.
uint32_t	av_crc (const AVCRC *ctx, uint32_t start_crc, const uint8_t *buffer, size_t length)
	Calculate the CRC of a block.

---

Typedef Documentation

typedef uint32_t AVCRC

Definition at line 27 of file crc.h.

---

Enumeration Type Documentation

enum AVCRCId

Enumerator:

AV_CRC_8_ATM
AV_CRC_16_ANSI
AV_CRC_16_CCITT
AV_CRC_32_IEEE
AV_CRC_32_IEEE_LE
AV_CRC_MAX

Definition at line 29 of file crc.h.

---

Function Documentation

uint32_t av_crc	(	const AVCRC *	ctx,
		uint32_t	crc,
		const uint8_t *	buffer,
		size_t	length
	)

Calculate the CRC of a block.

Parameters:

crc

CRC of previous blocks if any or initial value for CRC.

Returns:

CRC updated with the data from the given block

See also:

av_crc_init() "le" parameter

Definition at line 112 of file crc.c.

Referenced by ac3_decode_frame(), decode_frame(), ff_crc04C11DB7_update(), mlp_checksum16(), mpegts_write_section(), output_frame_end(), output_frame_footer(), output_frame_header(), and write_section_data().

const AVCRC* av_crc_get_table

(

AVCRCId

crc_id

)

Get an initialized standard CRC table.

Parameters:

crc_id

ID of a standard CRC

Returns:

a pointer to the CRC table or NULL on failure

Definition at line 92 of file crc.c.

Referenced by ac3_decode_frame(), decode_frame(), ff_crc04C11DB7_update(), mpegts_write_section(), output_frame_end(), output_frame_footer(), output_frame_header(), and write_section_data().

int av_crc_init	(	AVCRC *	ctx,
		int	le,
		int	bits,
		uint32_t	poly,
		int	ctx_size
	)

Inits a crc table.

Parameters:

	ctx	must be an array of sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
	cts_size	size of ctx in bytes
	le	if 1, lowest bit represents coefficient for highest exponent of corresponding polynomial (both for poly and actual CRC). If 0, you must swap the crc parameter and the result of av_crc if you need the standard representation (can be simplified in most cases to e.g. bswap16): bswap_32(crc << (32-bits))
	bits	number of bits for the CRC
	poly	generator polynomial without the x**bits coefficient, in the representation as specified by le

Returns:

<0 on failure

Definition at line 56 of file crc.c.

Referenced by av_crc_get_table(), and mlp_checksum16().