Simple lagged fibonacci PRNG.
[libav.git] / libavutil / lfg.h
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 #ifndef FFMPEG_LFG_H
23 #define FFMPEG_LFG_H
24
25 typedef struct {
26 unsigned int state[64];
27 int index;
28 } AVLFG;
29
30 void av_lfg_init(AVLFG *c, unsigned int seed);
31
32 static inline unsigned int av_lfg_get(AVLFG *c){
33 c->state[c->index & 63] = c->state[(c->index-24) & 63] + c->state[(c->index-55) & 63];
34 return c->state[c->index++ & 63];
35 }
36
37 #endif //FFMPEG_LFG_H