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108 lines
2.5 KiB
108 lines
2.5 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 <math.h> |
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#include <time.h> |
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#include "timer.h" |
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#include "random_seed.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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#ifdef TEST |
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#undef printf |
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#define N 256 |
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#include <stdio.h> |
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int main(void) |
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{ |
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int i, j, retry; |
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uint32_t seeds[N]; |
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for (retry=0; retry<3; retry++){ |
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for (i=0; i<N; i++){ |
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seeds[i] = av_get_random_seed(); |
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for (j=0; j<i; j++) |
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if (seeds[j] == seeds[i]) |
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goto retry; |
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} |
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printf("seeds OK\n"); |
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return 0; |
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retry:; |
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} |
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printf("FAIL at %d with %X\n", j, seeds[j]); |
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return 1; |
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} |
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#endif
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