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2754fe8ba5
3.5 times faster than our mersene twister. 10 times less memory needed. (=less cache trashing) Originally committed as revision 14458 to svn://svn.ffmpeg.org/ffmpeg/trunk
65 lines
1.7 KiB
C
65 lines
1.7 KiB
C
/*
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* Lagged Fibonacci PRNG
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* Copyright (c) 2008 Michael Niedermayer
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <inttypes.h>
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#include "lfg.h"
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#include "md5.h"
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#include "intreadwrite.h"
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void av_cold av_lfg_init(AVLFG *c, unsigned int seed){
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uint8_t tmp[16]={0};
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int i;
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for(i=8; i<64; i+=4){
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AV_WL32(tmp, seed); tmp[4]=i;
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av_md5_sum(tmp, tmp, 16);
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c->state[i ]= AV_RL32(tmp);
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c->state[i+1]= AV_RL32(tmp+4);
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c->state[i+2]= AV_RL32(tmp+8);
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c->state[i+3]= AV_RL32(tmp+12);
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}
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c->index=0;
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}
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#ifdef TEST
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#include "log.h"
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#include "common.h"
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int main(void)
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{
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int x=0;
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int i, j;
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AVLFG state;
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av_lfg_init(&state, 0xdeadbeef);
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for (j = 0; j < 10000; j++) {
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START_TIMER
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for (i = 0; i < 624; i++) {
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// av_log(NULL,AV_LOG_ERROR, "%X\n", av_lfg_get(&state));
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x+=av_lfg_get(&state);
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}
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STOP_TIMER("624 calls of av_random");
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}
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av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x);
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return 0;
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}
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#endif
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