diff options
Diffstat (limited to 'libavutil/random_seed.c')
-rw-r--r-- | libavutil/random_seed.c | 94 |
1 files changed, 70 insertions, 24 deletions
diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c index ec9caa7..c674704 100644 --- a/libavutil/random_seed.c +++ b/libavutil/random_seed.c @@ -1,20 +1,20 @@ /* * Copyright (c) 2009 Baptiste Coudurier <baptiste.coudurier@gmail.com> * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * 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. * - * Libav is distributed in the hope that it will be useful, + * 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 Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ @@ -30,8 +30,16 @@ #include <fcntl.h> #include <math.h> #include <time.h> +#include <string.h> +#include "avassert.h" #include "timer.h" #include "random_seed.h" +#include "sha.h" +#include "intreadwrite.h" + +#ifndef TEST +#define TEST 0 +#endif static int read_random(uint32_t *dst, const char *file) { @@ -52,34 +60,46 @@ static int read_random(uint32_t *dst, const char *file) static uint32_t get_generic_seed(void) { + uint8_t tmp[120]; + struct AVSHA *sha = (void*)tmp; clock_t last_t = 0; - int bits = 0; - uint64_t random = 0; - unsigned i; - float s = 0.000000000001; + static uint64_t i = 0; + static uint32_t buffer[512] = {0}; + unsigned char digest[20]; + uint64_t last_i = i; + + av_assert0(sizeof(tmp) >= av_sha_size); + + if(TEST){ + memset(buffer, 0, sizeof(buffer)); + last_i = i = 0; + }else{ +#ifdef AV_READ_TIME + buffer[13] ^= AV_READ_TIME(); + buffer[41] ^= AV_READ_TIME()>>32; +#endif + } - for (i = 0; bits < 64; i++) { + for (;;) { 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++; - } + + if(last_t == t){ + buffer[i&511]++; + }else{ + buffer[++i&511]+= (t-last_t) % 3294638521U; + if(last_i && i-last_i > 4 || i-last_i > 64 || TEST && i-last_i > 8) + break; } last_t = t; } -#ifdef AV_READ_TIME - random ^= AV_READ_TIME(); -#else - random ^= clock(); -#endif - random += random >> 32; + if(TEST) + buffer[0] = buffer[1] = 0; - return random; + av_sha_init(sha, 160); + av_sha_update(sha, (uint8_t*)buffer, sizeof(buffer)); + av_sha_final(sha, digest); + return AV_RB32(digest) + AV_RB32(digest+16); } uint32_t av_get_random_seed(void) @@ -103,3 +123,29 @@ uint32_t av_get_random_seed(void) return seed; return get_generic_seed(); } + +#if TEST +#undef printf +#define N 256 +#include <stdio.h> + +int main(void) +{ + int i, j, retry; + uint32_t seeds[N]; + + for (retry=0; retry<3; retry++){ + for (i=0; i<N; i++){ + seeds[i] = av_get_random_seed(); + for (j=0; j<i; j++) + if (seeds[j] == seeds[i]) + goto retry; + } + printf("seeds OK\n"); + return 0; + retry:; + } + printf("FAIL at %d with %X\n", j, seeds[j]); + return 1; +} +#endif |