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