1/*
2 * Lagged Fibonacci PRNG
3 * Copyright (c) 2008 Michael Niedermayer
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include <inttypes.h>
23#include "lfg.h"
24#include "md5.h"
25#include "intreadwrite.h"
26
27void av_cold av_lfg_init(AVLFG *c, unsigned int seed){
28    uint8_t tmp[16]={0};
29    int i;
30
31    for(i=8; i<64; i+=4){
32        AV_WL32(tmp, seed); tmp[4]=i;
33        av_md5_sum(tmp, tmp,  16);
34        c->state[i  ]= AV_RL32(tmp);
35        c->state[i+1]= AV_RL32(tmp+4);
36        c->state[i+2]= AV_RL32(tmp+8);
37        c->state[i+3]= AV_RL32(tmp+12);
38    }
39    c->index=0;
40}
41
42#ifdef TEST
43#include "log.h"
44#include "common.h"
45
46int main(void)
47{
48    int x=0;
49    int i, j;
50    AVLFG state;
51
52    av_lfg_init(&state, 0xdeadbeef);
53    for (j = 0; j < 10000; j++) {
54        START_TIMER
55        for (i = 0; i < 624; i++) {
56//            av_log(NULL,AV_LOG_ERROR, "%X\n", av_lfg_get(&state));
57            x+=av_lfg_get(&state);
58        }
59        STOP_TIMER("624 calls of av_random");
60    }
61    av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x);
62    return 0;
63}
64#endif
65