aarch64: Add assembly support for -fsanitize=hwaddress tagged globals.
[libav.git] / libavutil / lfg.c
1 /*
2 * Lagged Fibonacci PRNG
3 * Copyright (c) 2008 Michael Niedermayer
4 *
5 * This file is part of Libav.
6 *
7 * Libav 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 * Libav 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 Libav; 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 <limits.h>
24 #include <math.h>
25 #include "lfg.h"
26 #include "md5.h"
27 #include "intreadwrite.h"
28 #include "attributes.h"
29
30 av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
31 {
32 uint8_t tmp[16] = { 0 };
33 int i;
34
35 for (i = 8; i < 64; i += 4) {
36 AV_WL32(tmp, seed);
37 tmp[4] = i;
38 av_md5_sum(tmp, tmp, 16);
39 c->state[i ] = AV_RL32(tmp);
40 c->state[i + 1] = AV_RL32(tmp + 4);
41 c->state[i + 2] = AV_RL32(tmp + 8);
42 c->state[i + 3] = AV_RL32(tmp + 12);
43 }
44 c->index = 0;
45 }
46
47 void av_bmg_get(AVLFG *lfg, double out[2])
48 {
49 double x1, x2, w;
50
51 do {
52 x1 = 2.0 / UINT_MAX * av_lfg_get(lfg) - 1.0;
53 x2 = 2.0 / UINT_MAX * av_lfg_get(lfg) - 1.0;
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 }