libavutil/crc.c File Reference

#include "config.h"
#include "bswap.h"
#include "crc.h"

Go to the source code of this file.

Functions
int	av_crc_init (AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
	Initializes a CRC table.
const AVCRC *	av_crc_get_table (AVCRCId crc_id)
	Gets an initialized standard CRC table.
uint32_t	av_crc (const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length)
	Calculates the CRC of a block.
Variables
struct {
uint8_t   le
uint8_t   bits
uint32_t   poly
}	av_crc_table_params [AV_CRC_MAX]
static AVCRC	av_crc_table [AV_CRC_MAX][257]

---

Function Documentation

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

Calculates 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 114 of file crc.c.

Referenced by ac3_decode_frame(), decode_frame(), ff_crc04C11DB7_update(), ff_mlp_checksum16(), ff_mlp_checksum8(), ff_mlp_restart_checksum(), 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

)

Gets 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 94 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
	)

Initializes a CRC table.

Parameters:

	ctx	must be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
	cts_size	size of ctx in bytes
	le	If 1, the lowest bit represents the coefficient for the highest exponent of the 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 58 of file crc.c.

Referenced by av_crc_get_table(), and ff_mlp_init_crc().

---

Variable Documentation

AVCRC av_crc_table[AV_CRC_MAX][257] [static]

Definition at line 39 of file crc.c.

Referenced by av_crc_get_table().

struct { ... } av_crc_table_params[AV_CRC_MAX] [static]

Referenced by av_crc_get_table().

uint8_t bits

Definition at line 30 of file crc.c.

Referenced by aac_sync(), ac3_decode_transform_coeffs_ch(), adaptive_quantization(), av_crc_get_table(), avg_bits_per_pixel(), bit8x8_c(), build_huff_tree(), calc_rice_params(), calc_rice_params_fixed(), calc_rice_params_lpc(), calculate_band_sign_bits(), check_slice_end(), compute_mantissa_size(), decode_band_types(), decode_cabac_mb_type_b(), decode_i2_frame(), dnxhd_calc_ac_bits(), dnxhd_encode_rdo(), dnxhd_find_qscale(), dvbsub_read_2bit_string(), dvbsub_read_4bit_string(), dvbsub_read_8bit_string(), encode_block(), encode_frame(), encode_picture(), encode_residual(), encode_thread(), ff_copy_bits(), ff_eac3_decode_transform_coeffs_aht_ch(), ff_get_plane_bytewidth(), ff_mpeg1_encode_init(), ff_rate_control_init(), ff_rate_estimate_qscale(), ff_rv34_decode_init(), gb_get_v(), generate_bits_table(), generate_joint_tables(), get_bits_diff(), get_qscale(), imc_decode_frame(), init_pass2(), init_uni_ac_vlc(), modify_qscale(), mp_decode_layer2(), mpc7_decode_frame(), mpc8_dec_enum(), mpc8_decode_frame(), mpeg1_encode_motion(), nelly_decode_block(), put_codebook_header(), rd8x8_c(), read_huffman_tables(), readQuantSpectralCoeffs(), seq_decode_op1(), smka_decode_frame(), vorbis_parse_setup_hdr_floors(), vorbis_parse_setup_hdr_mappings(), vorbis_parse_setup_hdr_residues(), wp_log2(), and xan_huffman_decode().

uint8_t le

Definition at line 29 of file crc.c.

Referenced by av_crc_get_table(), and decode_frame().

uint32_t poly

Definition at line 31 of file crc.c.

Referenced by av_crc_get_table().