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