/* * Compute the Adler-32 checksum of a data stream. * This is a modified version based on adler32.c from the zlib library. * * Copyright (C) 1995 Mark Adler * * This software is provided 'as-is', without any express or implied * warranty. In no event will the authors be held liable for any damages * arising from the use of this software. * * Permission is granted to anyone to use this software for any purpose, * including commercial applications, and to alter it and redistribute it * freely, subject to the following restrictions: * * 1. The origin of this software must not be misrepresented; you must not * claim that you wrote the original software. If you use this software * in a product, an acknowledgment in the product documentation would be * appreciated but is not required. * 2. Altered source versions must be plainly marked as such, and must not be * misrepresented as being the original software. * 3. This notice may not be removed or altered from any source distribution. */ #include "config.h" #include "adler32.h" #define BASE 65521L /* largest prime smaller than 65536 */ #define DO1(buf) {s1 += *buf++; s2 += s1;} #define DO4(buf) DO1(buf); DO1(buf); DO1(buf); DO1(buf); #define DO16(buf) DO4(buf); DO4(buf); DO4(buf); DO4(buf); unsigned long av_adler32_update(unsigned long adler, const uint8_t *buf, unsigned int len) { unsigned long s1 = adler & 0xffff; unsigned long s2 = adler >> 16; while (len>0) { #if CONFIG_SMALL while(len>4 && s2 < (1U<<31)){ DO4(buf); len-=4; #else while(len>16 && s2 < (1U<<31)){ DO16(buf); len-=16; #endif } DO1(buf); len--; s1 %= BASE; s2 %= BASE; } return (s2 << 16) | s1; } #ifdef TEST #include "log.h" #include "timer.h" #define LEN 7001 volatile int checksum; int main(void){ int i; char data[LEN]; av_log_set_level(AV_LOG_DEBUG); for(i=0; i<LEN; i++) data[i]= ((i*i)>>3) + 123*i; for(i=0; i<1000; i++){ START_TIMER checksum= av_adler32_update(1, data, LEN); STOP_TIMER("adler") } av_log(NULL, AV_LOG_DEBUG, "%X == 50E6E508\n", checksum); return 0; } #endif