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