1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
|
/*
* copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
*
* This file is part of Libav.
*
* Libav 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.
*
* Libav 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 Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "config.h"
#include "common.h"
#include "bswap.h"
#include "crc.h"
#if CONFIG_HARDCODED_TABLES
#include "crc_data.h"
#else
static struct {
uint8_t le;
uint8_t bits;
uint32_t poly;
} av_crc_table_params[AV_CRC_MAX] = {
[AV_CRC_8_ATM] = { 0, 8, 0x07 },
[AV_CRC_16_ANSI] = { 0, 16, 0x8005 },
[AV_CRC_16_CCITT] = { 0, 16, 0x1021 },
[AV_CRC_32_IEEE] = { 0, 32, 0x04C11DB7 },
[AV_CRC_32_IEEE_LE] = { 1, 32, 0xEDB88320 },
};
static AVCRC av_crc_table[AV_CRC_MAX][257];
#endif
int av_crc_init(AVCRC *ctx, int le, int bits, uint32_t poly, int ctx_size)
{
unsigned 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] = av_bswap32(c);
}
}
ctx[256] = 1;
#if !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;
}
const AVCRC *av_crc_get_table(AVCRCId crc_id)
{
#if !CONFIG_HARDCODED_TABLES
if (!av_crc_table[crc_id][FF_ARRAY_ELEMS(av_crc_table[crc_id]) - 1])
if (av_crc_init(av_crc_table[crc_id],
av_crc_table_params[crc_id].le,
av_crc_table_params[crc_id].bits,
av_crc_table_params[crc_id].poly,
sizeof(av_crc_table[crc_id])) < 0)
return NULL;
#endif
return av_crc_table[crc_id];
}
uint32_t av_crc(const AVCRC *ctx, uint32_t crc,
const uint8_t *buffer, size_t length)
{
const uint8_t *end = buffer + length;
#if !CONFIG_SMALL
if (!ctx[256]) {
while (((intptr_t) buffer & 3) && buffer < end)
crc = ctx[((uint8_t) crc) ^ *buffer++] ^ (crc >> 8);
while (buffer < end - 3) {
crc ^= av_le2ne32(*(const 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
int main(void)
{
uint8_t buf[1999];
int i;
int p[4][3] = { { AV_CRC_32_IEEE_LE, 0xEDB88320, 0x3D5CDD04 },
{ AV_CRC_32_IEEE , 0x04C11DB7, 0xC0F5BAE0 },
{ AV_CRC_16_ANSI , 0x8005 , 0x1FBB },
{ AV_CRC_8_ATM , 0x07 , 0xE3 }
};
const AVCRC *ctx;
for (i = 0; i < sizeof(buf); i++)
buf[i] = i + i * i;
for (i = 0; i < 4; i++) {
ctx = av_crc_get_table(p[i][0]);
printf("crc %08X = %X\n", p[i][1], av_crc(ctx, 0, buf, sizeof(buf)));
}
return 0;
}
#endif
|
