PeerStreamer

/*

 * Lagged Fibonacci PRNG

 * Copyright (c) 2008 Michael Niedermayer

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include <inttypes.h>

#include "lfg.h"

#include "md5.h"

#include "intreadwrite.h"

void av_cold av_lfg_init(AVLFG *c, unsigned int seed){

    uint8_t tmp[16]={0};

    int i;

    for(i=8; i<64; i+=4){

        AV_WL32(tmp, seed); tmp[4]=i;

        av_md5_sum(tmp, tmp,  16);

        c->state[i  ]= AV_RL32(tmp);

        c->state[i+1]= AV_RL32(tmp+4);

        c->state[i+2]= AV_RL32(tmp+8);

        c->state[i+3]= AV_RL32(tmp+12);

    }

    c->index=0;

}

#ifdef TEST

#include "log.h"

#include "common.h"

int main(void)

{

    int x=0;

    int i, j;

    AVLFG state;

    av_lfg_init(&state, 0xdeadbeef);

    for (j = 0; j < 10000; j++) {

        START_TIMER

        for (i = 0; i < 624; i++) {

//            av_log(NULL,AV_LOG_ERROR, "%X\n", av_lfg_get(&state));

            x+=av_lfg_get(&state);

        }

        STOP_TIMER("624 calls of av_lfg_get");

    }

    av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x);

    return 0;

}

#endif