mirror of
https://git.videolan.org/git/ffmpeg.git
synced 2024-08-18 23:35:06 +02:00
112 lines
3.2 KiB
C
112 lines
3.2 KiB
C
/*
|
|
* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
|
|
*
|
|
* This file is part of FFmpeg.
|
|
*
|
|
* FFmpeg is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU Lesser General Public
|
|
* License as published by the Free Software Foundation; either
|
|
* version 2.1 of the License, or (at your option) any later version.
|
|
*
|
|
* FFmpeg is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* Lesser General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU Lesser General Public
|
|
* License along with FFmpeg; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
#include "common.h"
|
|
#include "crc.h"
|
|
|
|
#if LIBAVUTIL_VERSION_INT < (50<<16)
|
|
AVCRC *av_crcEDB88320;
|
|
AVCRC *av_crc04C11DB7;
|
|
AVCRC *av_crc8005 ;
|
|
AVCRC *av_crc07 ;
|
|
#else
|
|
AVCRC av_crcEDB88320[257];
|
|
AVCRC av_crc04C11DB7[257];
|
|
AVCRC av_crc8005 [257];
|
|
AVCRC av_crc07 [257];
|
|
#endif
|
|
|
|
/**
|
|
* Inits a crc table.
|
|
* @param ctx must be an array of sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
|
|
* @param cts_size size of ctx in bytes
|
|
* @return <0 on failure
|
|
*/
|
|
int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size){
|
|
int i, j;
|
|
uint32_t c;
|
|
|
|
if (bits < 8 || bits > 32 || poly >= (1LL<<bits))
|
|
return -1;
|
|
if (ctx_size != sizeof(AVCRC)*257 && ctx_size != sizeof(AVCRC)*1024)
|
|
return -1;
|
|
|
|
for (i = 0; i < 256; i++) {
|
|
if (le) {
|
|
for (c = i, j = 0; j < 8; j++)
|
|
c = (c>>1)^(poly & (-(c&1)));
|
|
ctx[i] = c;
|
|
} else {
|
|
for (c = i << 24, j = 0; j < 8; j++)
|
|
c = (c<<1) ^ ((poly<<(32-bits)) & (((int32_t)c)>>31) );
|
|
ctx[i] = bswap_32(c);
|
|
}
|
|
}
|
|
ctx[256]=1;
|
|
#ifndef CONFIG_SMALL
|
|
if(ctx_size >= sizeof(AVCRC)*1024)
|
|
for (i = 0; i < 256; i++)
|
|
for(j=0; j<3; j++)
|
|
ctx[256*(j+1) + i]= (ctx[256*j + i]>>8) ^ ctx[ ctx[256*j + i]&0xFF ];
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length){
|
|
const uint8_t *end= buffer+length;
|
|
|
|
#ifndef CONFIG_SMALL
|
|
if(!ctx[256])
|
|
while(buffer<end-3){
|
|
crc ^= le2me_32(*(uint32_t*)buffer); buffer+=4;
|
|
crc = ctx[3*256 + ( crc &0xFF)]
|
|
^ctx[2*256 + ((crc>>8 )&0xFF)]
|
|
^ctx[1*256 + ((crc>>16)&0xFF)]
|
|
^ctx[0*256 + ((crc>>24) )];
|
|
}
|
|
#endif
|
|
while(buffer<end)
|
|
crc = ctx[((uint8_t)crc) ^ *buffer++] ^ (crc >> 8);
|
|
|
|
return crc;
|
|
}
|
|
|
|
#ifdef TEST
|
|
#undef printf
|
|
main(){
|
|
uint8_t buf[1999];
|
|
int i;
|
|
int p[4][4]={{1, 32, 0xedb88320L, 0x3D5CDD04},
|
|
{0, 32, 0x04c11db7L, 0xC0F5BAE0},
|
|
{0, 16, 0x8005 , 0x1FBB },
|
|
{0, 8, 0x07 , 0xE3 },};
|
|
AVCRC ctx[1 ? 1024:257];
|
|
|
|
for(i=0; i<sizeof(buf); i++)
|
|
buf[i]= i+i*i;
|
|
|
|
for(i=0; i<4; i++){
|
|
av_crc_init(ctx, p[i][0], p[i][1], p[i][2], sizeof(ctx));
|
|
printf("crc %08X =%X\n", p[i][2], av_crc(ctx, 0, buf, sizeof(buf)));
|
|
}
|
|
}
|
|
#endif
|