mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
53 lines
1.3 KiB
53 lines
1.3 KiB
/* adler32.c -- compute the Adler-32 checksum of a data stream |
|
* Copyright (C) 1995 Mark Adler |
|
* For conditions of distribution and use, see copyright notice in zlib.h |
|
*/ |
|
|
|
#include "common.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) { |
|
#ifdef 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" |
|
#define LEN 7001 |
|
volatile int checksum; |
|
int main(){ |
|
int i; |
|
char data[LEN]; |
|
av_log_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); |
|
} |
|
#endif
|
|
|