2 * Compute the Adler-32 checksum of a data stream.
3 * This is a modified version based on adler32.c from the zlib library.
5 * Copyright (C) 1995 Mark Adler
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.
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:
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.
27 #define BASE 65521L /* largest prime smaller than 65536 */
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);
33 unsigned long av_adler32_update(unsigned long adler, const uint8_t * buf,
36 unsigned long s1 = adler & 0xffff;
37 unsigned long s2 = adler >> 16;
41 while (len > 4 && s2 < (1U << 31)) {
46 while (len > 16 && s2 < (1U << 31)) {
55 return (s2 << 16) | s1;
64 volatile int checksum;
65 int main(int argc, char **argv)
70 av_log_set_level(AV_LOG_DEBUG);
72 for (i = 0; i < LEN; i++)
73 data[i] = ((i * i) >> 3) + 123 * i;
75 if (argc > 1 && !strcmp(argv[1], "-t")) {
76 for (i = 0; i < 1000; i++) {
78 checksum = av_adler32_update(1, data, LEN);
82 checksum = av_adler32_update(1, data, LEN);
85 av_log(NULL, AV_LOG_DEBUG, "%X (expected 50E6E508)\n", checksum);
86 return checksum == 0x50e6e508 ? 0 : 1;