| /* |
| * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg 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. |
| * |
| * FFmpeg 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 FFmpeg; 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 |