1/*
2 * Compute the Adler-32 checksum of a data stream.
3 * This is a modified version based on adler32.c from the zlib library.
4 *
5 * Copyright (C) 1995 Mark Adler
6 *
7 * This software is provided 'as-is', without any express or implied
8 * warranty.  In no event will the authors be held liable for any damages
9 * arising from the use of this software.
10 *
11 * Permission is granted to anyone to use this software for any purpose,
12 * including commercial applications, and to alter it and redistribute it
13 * freely, subject to the following restrictions:
14 *
15 * 1. The origin of this software must not be misrepresented; you must not
16 *    claim that you wrote the original software. If you use this software
17 *    in a product, an acknowledgment in the product documentation would be
18 *    appreciated but is not required.
19 * 2. Altered source versions must be plainly marked as such, and must not be
20 *    misrepresented as being the original software.
21 * 3. This notice may not be removed or altered from any source distribution.
22 */
23
24#include "config.h"
25#include "adler32.h"
26
27#define BASE 65521L /* largest prime smaller than 65536 */
28
29#define DO1(buf)  { s1 += *buf++; s2 += s1; }
30#define DO4(buf)  DO1(buf); DO1(buf); DO1(buf); DO1(buf);
31#define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf);
32
33unsigned long av_adler32_update(unsigned long adler, const uint8_t * buf,
34                                unsigned int len)
35{
36    unsigned long s1 = adler & 0xffff;
37    unsigned long s2 = adler >> 16;
38
39    while (len > 0) {
40#if CONFIG_SMALL
41        while (len > 4  && s2 < (1U << 31)) {
42            DO4(buf);
43            len -= 4;
44        }
45#else
46        while (len > 16 && s2 < (1U << 31)) {
47            DO16(buf);
48            len -= 16;
49        }
50#endif
51        DO1(buf); len--;
52        s1 %= BASE;
53        s2 %= BASE;
54    }
55    return (s2 << 16) | s1;
56}
57
58#ifdef TEST
59#include <string.h>
60#include "log.h"
61#include "timer.h"
62#define LEN 7001
63
64static volatile int checksum;
65
66int main(int argc, char **argv)
67{
68    int i;
69    char data[LEN];
70
71    av_log_set_level(AV_LOG_DEBUG);
72
73    for (i = 0; i < LEN; i++)
74        data[i] = ((i * i) >> 3) + 123 * i;
75
76    if (argc > 1 && !strcmp(argv[1], "-t")) {
77        for (i = 0; i < 1000; i++) {
78            START_TIMER;
79            checksum = av_adler32_update(1, data, LEN);
80            STOP_TIMER("adler");
81        }
82    } else {
83        checksum = av_adler32_update(1, data, LEN);
84    }
85
86    av_log(NULL, AV_LOG_DEBUG, "%X (expected 50E6E508)\n", checksum);
87    return checksum == 0x50e6e508 ? 0 : 1;
88}
89#endif
90