FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavutil/lfg.c
Date: 2024-02-16 17:37:06
Exec Total Coverage
Lines: 21 33 63.6%
Functions: 2 3 66.7%
Branches: 4 8 50.0%

Line Branch Exec Source
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 <limits.h>
24 #include <math.h>
25 #include "lfg.h"
26 #include "crc.h"
27 #include "md5.h"
28 #include "error.h"
29 #include "intreadwrite.h"
30 #include "attributes.h"
31
32 329 av_cold void av_lfg_init(AVLFG *c, unsigned int seed)
33 {
34 329 uint8_t tmp[16] = { 0 };
35 int i;
36
37
2/2
✓ Branch 0 taken 4606 times.
✓ Branch 1 taken 329 times.
4935 for (i = 8; i < 64; i += 4) {
38 4606 AV_WL32(tmp, seed);
39 4606 tmp[4] = i;
40 4606 av_md5_sum(tmp, tmp, 16);
41 4606 c->state[i ] = AV_RL32(tmp);
42 4606 c->state[i + 1] = AV_RL32(tmp + 4);
43 4606 c->state[i + 2] = AV_RL32(tmp + 8);
44 4606 c->state[i + 3] = AV_RL32(tmp + 12);
45 }
46 329 c->index = 0;
47 329 }
48
49 36780 void av_bmg_get(AVLFG *lfg, double out[2])
50 {
51 double x1, x2, w;
52
53 do {
54 46857 x1 = 2.0 / UINT_MAX * av_lfg_get(lfg) - 1.0;
55 46857 x2 = 2.0 / UINT_MAX * av_lfg_get(lfg) - 1.0;
56 46857 w = x1 * x1 + x2 * x2;
57
2/2
✓ Branch 0 taken 10077 times.
✓ Branch 1 taken 36780 times.
46857 } while (w >= 1.0);
58
59 36780 w = sqrt((-2.0 * log(w)) / w);
60 36780 out[0] = x1 * w;
61 36780 out[1] = x2 * w;
62 36780 }
63
64 int av_lfg_init_from_data(AVLFG *c, const uint8_t *data, unsigned int length) {
65 unsigned int beg, end, segm;
66 const AVCRC *avcrc;
67 uint32_t crc = 1;
68
69 /* avoid integer overflow in the loop below. */
70 if (length > (UINT_MAX / 128U)) return AVERROR(EINVAL);
71
72 c->index = 0;
73 avcrc = av_crc_get_table(AV_CRC_32_IEEE); /* This can't fail. It's a well-defined table in crc.c */
74
75 /* across 64 segments of the incoming data,
76 * do a running crc of each segment and store the crc as the state for that slot.
77 * this works even if the length of the segment is 0 bytes. */
78 beg = 0;
79 for (segm = 0;segm < 64;segm++) {
80 end = (((segm + 1) * length) / 64);
81 crc = av_crc(avcrc, crc, data + beg, end - beg);
82 c->state[segm] = (unsigned int)crc;
83 beg = end;
84 }
85
86 return 0;
87 }
88