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
|
/*
* Compute the Adler-32 checksum of a data stream.
* This is a modified version based on adler32.c from the zlib library.
*
* Copyright (C) 1995 Mark Adler
*
* This software is provided 'as-is', without any express or implied
* warranty. In no event will the authors be held liable for any damages
* arising from the use of this software.
*
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
*
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
* misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
*/
/**
* @file
* Computes the Adler-32 checksum of a data stream
*
* This is a modified version based on adler32.c from the zlib library.
* @author Mark Adler
* @ingroup lavu_adler32
*/
#include "config.h"
#include "adler32.h"
#define BASE 65521L /* largest prime smaller than 65536 */
#define DO1(buf) { s1 += *buf++; s2 += s1; }
#define DO4(buf) DO1(buf); DO1(buf); DO1(buf); DO1(buf);
#define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf);
unsigned long av_adler32_update(unsigned long adler, const uint8_t * buf,
unsigned int len)
{
unsigned long s1 = adler & 0xffff;
unsigned long s2 = adler >> 16;
while (len > 0) {
#if CONFIG_SMALL
while (len > 4 && s2 < (1U << 31)) {
DO4(buf);
len -= 4;
}
#else
while (len > 16 && s2 < (1U << 31)) {
DO16(buf);
len -= 16;
}
#endif
DO1(buf); len--;
s1 %= BASE;
s2 %= BASE;
}
return (s2 << 16) | s1;
}
#ifdef TEST
#include <string.h>
#include "log.h"
#include "timer.h"
#define LEN 7001
static volatile int checksum;
int main(int argc, char **argv)
{
int i;
char data[LEN];
av_log_set_level(AV_LOG_DEBUG);
for (i = 0; i < LEN; i++)
data[i] = ((i * i) >> 3) + 123 * i;
if (argc > 1 && !strcmp(argv[1], "-t")) {
for (i = 0; i < 1000; i++) {
START_TIMER;
checksum = av_adler32_update(1, data, LEN);
STOP_TIMER("adler");
}
} else {
checksum = av_adler32_update(1, data, LEN);
}
av_log(NULL, AV_LOG_DEBUG, "%X (expected 50E6E508)\n", checksum);
return checksum == 0x50e6e508 ? 0 : 1;
}
#endif
|
