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 "common.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, unsigned int len) 34{ 35 unsigned long s1 = adler & 0xffff; 36 unsigned long s2 = adler >> 16; 37 38 while (len>0) { 39#if CONFIG_SMALL 40 while(len>4 && s2 < (1U<<31)){ 41 DO4(buf); len-=4; 42#else 43 while(len>16 && s2 < (1U<<31)){ 44 DO16(buf); len-=16; 45#endif 46 } 47 DO1(buf); len--; 48 s1 %= BASE; 49 s2 %= BASE; 50 } 51 return (s2 << 16) | s1; 52} 53 54#ifdef TEST 55#include "log.h" 56#define LEN 7001 57volatile int checksum; 58int main(void){ 59 int i; 60 char data[LEN]; 61 av_log_level = AV_LOG_DEBUG; 62 for(i=0; i<LEN; i++) 63 data[i]= ((i*i)>>3) + 123*i; 64 for(i=0; i<1000; i++){ 65 START_TIMER 66 checksum= av_adler32_update(1, data, LEN); 67 STOP_TIMER("adler") 68 } 69 av_log(NULL, AV_LOG_DEBUG, "%X == 50E6E508\n", checksum); 70 return 0; 71} 72#endif 73