1 /* adler32.c -- compute the Adler-32 checksum of a data stream
2 * This is a modified version based on adler32.c from the zlib library.
4 * Copyright (C) 1995 Mark Adler
6 * This software is provided 'as-is', without any express or implied
7 * warranty. In no event will the authors be held liable for any damages
8 * arising from the use of this software.
10 * Permission is granted to anyone to use this software for any purpose,
11 * including commercial applications, and to alter it and redistribute it
12 * freely, subject to the following restrictions:
14 * 1. The origin of this software must not be misrepresented; you must not
15 * claim that you wrote the original software. If you use this software
16 * in a product, an acknowledgment in the product documentation would be
17 * appreciated but is not required.
18 * 2. Altered source versions must be plainly marked as such, and must not be
19 * misrepresented as being the original software.
20 * 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, unsigned int len)
35 unsigned long s1 = adler & 0xffff;
36 unsigned long s2 = adler >> 16;
40 while(len>4 && s2 < (1U<<31)){
43 while(len>16 && s2 < (1U<<31)){
51 return (s2 << 16) | s1;
57 volatile int checksum;
61 av_log_level = AV_LOG_DEBUG;
63 data[i]= ((i*i)>>3) + 123*i;
64 for(i=0; i<1000; i++){
66 checksum= av_adler32_update(1, data, LEN);
69 av_log(NULL, AV_LOG_DEBUG, "%X == 50E6E508\n", checksum);