ffmpeg.libavutil.lfg source code

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 module ffmpeg.libavutil.lfg;
23 
24 extern (C):
25 import ffmpeg; @nogc nothrow:
26 
27 struct AVLFG
28 {
29     uint[64] state;
30     int index;
31 }
32 
33 void av_lfg_init (AVLFG* c, uint seed);
34 
35 /**
36  * Seed the state of the ALFG using binary data.
37  *
38  * Return value: 0 on success, negative value (AVERROR) on failure.
39  */
40 int av_lfg_init_from_data (AVLFG* c, const(ubyte)* data, uint length);
41 
42 /**
43  * Get the next random unsigned 32-bit number using an ALFG.
44  *
45  * Please also consider a simple LCG like state= state*1664525+1013904223,
46  * it may be good enough and faster for your specific use case.
47  */
48 uint av_lfg_get (AVLFG* c);
49 
50 /**
51  * Get the next random unsigned 32-bit number using a MLFG.
52  *
53  * Please also consider av_lfg_get() above, it is faster.
54  */
55 uint av_mlfg_get (AVLFG* c);
56 
57 /**
58  * Get the next two numbers generated by a Box-Muller Gaussian
59  * generator using the random numbers issued by lfg.
60  *
61  * @param out array where the two generated numbers are placed
62  */
63 void av_bmg_get (AVLFG* lfg, ref double[2] out_);
64 
65 /* AVUTIL_LFG_H */