Remove old MSVC remnants.
[libav.git] / libavutil / crc.c
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1#include "common.h"
2#include "crc.h"
3
4AVCRC *av_crcEDB88320;
5AVCRC *av_crc04C11DB7;
6AVCRC *av_crc8005 ;
7AVCRC *av_crc07 ;
8
9/**
10 * Inits a crc table.
11 * @param ctx must be an array of sizeof(AVCRC)*257 or sizeof(AVCRC)*1024
12 * @param cts_size size of ctx in bytes
13 * @return <0 on failure
14 */
15int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size){
16 int i, j;
17 uint32_t c;
18
19 if (bits < 8 || bits > 32 || poly >= (1LL<<bits))
20 return -1;
21 if (ctx_size != sizeof(AVCRC)*257 && ctx_size != sizeof(AVCRC)*1024)
22 return -1;
23
24 for (i = 0; i < 256; i++) {
25 if (le) {
26 for (c = i, j = 0; j < 8; j++)
27 c = (c>>1)^(poly & (-(c&1)));
28 ctx[i] = c;
29 } else {
30 for (c = i << 24, j = 0; j < 8; j++)
31 c = (c<<1) ^ ((poly<<(32-bits)) & (((int32_t)c)>>31) );
32 ctx[i] = bswap_32(c);
33 }
34 }
35 ctx[256]=1;
a08d38ee 36#ifndef CONFIG_SMALL
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37 if(ctx_size >= sizeof(AVCRC)*1024)
38 for (i = 0; i < 256; i++)
39 for(j=0; j<3; j++)
40 ctx[256*(j+1) + i]= (ctx[256*j + i]>>8) ^ ctx[ ctx[256*j + i]&0xFF ];
a08d38ee 41#endif
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42
43 return 0;
44}
45
46uint32_t av_crc(const AVCRC *ctx, uint32_t crc, const uint8_t *buffer, size_t length){
47 const uint8_t *end= buffer+length;
48
a08d38ee 49#ifndef CONFIG_SMALL
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50 if(!ctx[256])
51 while(buffer<end-3){
52 crc ^= le2me_32(*(uint32_t*)buffer); buffer+=4;
53 crc = ctx[3*256 + ( crc &0xFF)]
54 ^ctx[2*256 + ((crc>>8 )&0xFF)]
55 ^ctx[1*256 + ((crc>>16)&0xFF)]
56 ^ctx[0*256 + ((crc>>24) )];
57 }
a08d38ee 58#endif
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59 while(buffer<end)
60 crc = ctx[((uint8_t)crc) ^ *buffer++] ^ (crc >> 8);
61
62 return crc;
63}
64
65#ifdef TEST
66#undef printf
67main(){
68 uint8_t buf[1999];
69 int i;
70 int p[4][4]={{1, 32, 0xedb88320L, 0x3D5CDD04},
71 {0, 32, 0x04c11db7L, 0xC0F5BAE0},
72 {0, 16, 0x8005 , 0x1FBB },
73 {0, 8, 0x07 , 0xE3 },};
74 AVCRC ctx[1 ? 1024:257];
75
76 for(i=0; i<sizeof(buf); i++)
77 buf[i]= i+i*i;
78
79 for(i=0; i<4; i++){
80 av_crc_init(ctx, p[i][0], p[i][1], p[i][2], sizeof(ctx));
81 printf("crc %08X =%X\n", p[i][2], av_crc(ctx, 0, buf, sizeof(buf)));
82 }
83}
84#endif