get rid of the last svn mentions
[libav.git] / libavutil / random_seed.c
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1/*
2 * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21#include <unistd.h>
22#include <fcntl.h>
23#include "timer.h"
c84d5aa7 24#include "time.h"
48d58e59 25#include "random_seed.h"
576fb48e 26#include "avutil.h"
48d58e59 27
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28static int read_random(uint32_t *dst, const char *file)
29{
30 int fd = open(file, O_RDONLY);
31 int err = -1;
32
33 if (fd == -1)
34 return -1;
9958096e 35 err = read(fd, dst, sizeof(*dst));
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36 close(fd);
37
38 return err;
39}
40
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41static uint32_t get_generic_seed(void)
42{
6a522c49 43 clock_t last_t=0;
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44 int bits=0;
45 uint64_t random=0;
b65c1ccf 46 unsigned i;
6a522c49 47 float s=0.000000000001;
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48
49 for(i=0;bits<64;i++){
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50 clock_t t= clock();
51 if(last_t && fabs(t-last_t)>s || t==(clock_t)-1){
52 if(i<10000 && s<(1<<24)){
53 s+=s;
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54 i=t=0;
55 }else{
56 random= 2*random + (i&1);
57 bits++;
58 }
59 }
60 last_t= t;
61 }
62#ifdef AV_READ_TIME
63 random ^= AV_READ_TIME();
64#else
65 random ^= clock();
66#endif
67
68 random += random>>32;
69
70 return random;
71}
72
576fb48e 73uint32_t av_get_random_seed(void)
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74{
75 uint32_t seed;
38e23c88 76
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77 if (read_random(&seed, "/dev/urandom") == sizeof(seed))
78 return seed;
79 if (read_random(&seed, "/dev/random") == sizeof(seed))
38e23c88 80 return seed;
c84d5aa7 81 return get_generic_seed();
48d58e59 82}
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83
84#if LIBAVUTIL_VERSION_MAJOR < 51
85attribute_deprecated uint32_t ff_random_get_seed(void);
86uint32_t ff_random_get_seed(void)
87{
88 return av_get_random_seed();
89}
90#endif