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>
24 #include <math.h>
29
31 {
34
35 for (i = 8; i < 64; i += 4) {
43 }
45 }
46
48 {
49 double x1, x2, w;
50
51 do {
54 w = x1 * x1 + x2 * x2;
55 } while (w >= 1.0);
56
57 w = sqrt((-2.0 * log(w)) / w);
58 out[0] = x1 * w;
59 out[1] = x2 * w;
60 }
61
62 #ifdef TEST
64 #include "timer.h"
65
67 {
68 int x = 0;
71
73 for (j = 0; j < 10000; j++) {
75 for (i = 0; i < 624; i++) {
76 //av_log(NULL, AV_LOG_ERROR, "%X\n", av_lfg_get(&state));
78 }
80 }
82
83 /* BMG usage example */
84 {
85 double mean = 1000;
86 double stddev = 53;
87
89
90 for (i = 0; i < 1000; i += 2) {
91 double bmg_out[2];
94 "%f\n%f\n",
95 bmg_out[0] * stddev + mean,
96 bmg_out[1] * stddev + mean);
97 }
98 }
99
100 return 0;
101 }
102 #endif
Macro definitions for various function/variable attributes.
void av_md5_sum(uint8_t *dst, const uint8_t *src, const int len)
Hash an array of data.
void av_bmg_get(AVLFG *lfg, double out[2])
Get the next two numbers generated by a Box-Muller Gaussian generator using the random numbers issued...
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
#define AV_LOG_INFO
Standard information.
static unsigned int av_lfg_get(AVLFG *c)
Get the next random unsigned 32-bit number using an ALFG.
av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
int main(int argc, char **argv)
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_RL32