FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
Files | Typedefs | Enumerations | Functions

CRC (Cyclic Redundancy Check) hash function implementation. More...

Files

file  crc.h
 Public header for CRC hash function implementation.
 

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_16_ANSI_LE, AV_CRC_24_IEEE, AV_CRC_MAX
}
 

Functions

int av_crc_init (AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
 Initialize a CRC table. More...
 
const AVCRCav_crc_get_table (AVCRCId crc_id)
 Get an initialized standard CRC table. More...
 
uint32_t av_crc (const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length) av_pure
 Calculate the CRC of a block. More...
 

Detailed Description

CRC (Cyclic Redundancy Check) hash function implementation.

This module supports numerous CRC polynomials, in addition to the most widely used CRC-32-IEEE. See AVCRCId for a list of available polynomials.

Typedef Documentation

typedef uint32_t AVCRC

Definition at line 47 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_16_ANSI_LE 
AV_CRC_24_IEEE 
AV_CRC_MAX 

Definition at line 49 of file crc.h.

Function Documentation

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

Initialize a CRC table.

Parameters
ctxmust be an array of size sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
leIf 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): av_bswap32(crc << (32-bits))
bitsnumber of bits for the CRC
polygenerator polynomial without the x**bits coefficient, in the representation as specified by le
ctx_sizesize of ctx in bytes
Returns
<0 on failure

Definition at line 316 of file crc.c.

Referenced by ff_mlp_init_crc().

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