mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
90 lines
2.2 KiB
90 lines
2.2 KiB
/* |
|
* Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com> |
|
* |
|
* This file is part of Libav. |
|
* |
|
* Libav is free software; you can redistribute it and/or |
|
* modify it under the terms of the GNU Lesser General Public |
|
* License as published by the Free Software Foundation; either |
|
* version 2.1 of the License, or (at your option) any later version. |
|
* |
|
* Libav is distributed in the hope that it will be useful, |
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of |
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|
* Lesser General Public License for more details. |
|
* |
|
* You should have received a copy of the GNU Lesser General Public |
|
* License along with Libav; if not, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
|
|
#include <unistd.h> |
|
#include <fcntl.h> |
|
#include "timer.h" |
|
#include "time.h" |
|
#include "random_seed.h" |
|
#include "avutil.h" |
|
|
|
static int read_random(uint32_t *dst, const char *file) |
|
{ |
|
int fd = open(file, O_RDONLY); |
|
int err = -1; |
|
|
|
if (fd == -1) |
|
return -1; |
|
err = read(fd, dst, sizeof(*dst)); |
|
close(fd); |
|
|
|
return err; |
|
} |
|
|
|
static uint32_t get_generic_seed(void) |
|
{ |
|
clock_t last_t=0; |
|
int bits=0; |
|
uint64_t random=0; |
|
unsigned i; |
|
float s=0.000000000001; |
|
|
|
for(i=0;bits<64;i++){ |
|
clock_t t= clock(); |
|
if(last_t && fabs(t-last_t)>s || t==(clock_t)-1){ |
|
if(i<10000 && s<(1<<24)){ |
|
s+=s; |
|
i=t=0; |
|
}else{ |
|
random= 2*random + (i&1); |
|
bits++; |
|
} |
|
} |
|
last_t= t; |
|
} |
|
#ifdef AV_READ_TIME |
|
random ^= AV_READ_TIME(); |
|
#else |
|
random ^= clock(); |
|
#endif |
|
|
|
random += random>>32; |
|
|
|
return random; |
|
} |
|
|
|
uint32_t av_get_random_seed(void) |
|
{ |
|
uint32_t seed; |
|
|
|
if (read_random(&seed, "/dev/urandom") == sizeof(seed)) |
|
return seed; |
|
if (read_random(&seed, "/dev/random") == sizeof(seed)) |
|
return seed; |
|
return get_generic_seed(); |
|
} |
|
|
|
#if LIBAVUTIL_VERSION_MAJOR < 51 |
|
attribute_deprecated uint32_t ff_random_get_seed(void); |
|
uint32_t ff_random_get_seed(void) |
|
{ |
|
return av_get_random_seed(); |
|
} |
|
#endif
|
|
|