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| author | Michael Niedermayer <michael@niedermayer.cc> | 2016-12-22 03:59:03 +0100 |
|---|---|---|
| committer | Michael Niedermayer <michael@niedermayer.cc> | 2016-12-22 12:40:48 +0100 |
| commit | da73d95bad4736c5e0a6b4b1a811f4dd4525bb4c (patch) | |
| tree | ef11f50bfdf637a8bb4cc38d393c081683d0983f | |
| parent | 0098eeaa62899136caf61aa76e3be2c198144ecc (diff) | |
| download | ffmpeg-da73d95bad4736c5e0a6b4b1a811f4dd4525bb4c.tar.gz | |
avutil/random_seed: Improve get_generic_seed() with higher precission clock()
Tested-by: Thomas Turner <thomastdt@googlemail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
| -rw-r--r-- | libavutil/random_seed.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c index 79bc7aff74..179fb23624 100644 --- a/libavutil/random_seed.c +++ b/libavutil/random_seed.c @@ -67,6 +67,7 @@ static uint32_t get_generic_seed(void) uint64_t tmp[120/8]; struct AVSHA *sha = (void*)tmp; clock_t last_t = 0; + clock_t last_td = 0; static uint64_t i = 0; static uint32_t buffer[512] = { 0 }; unsigned char digest[20]; @@ -86,11 +87,12 @@ static uint32_t get_generic_seed(void) for (;;) { clock_t t = clock(); - - if (last_t == t) { - buffer[i & 511]++; + if (last_t + 2*last_td + 1 >= t) { + last_td = t - last_t; + buffer[i & 511] = 1664525*buffer[i & 511] + 1013904223 + (last_td % 3294638521U); } else { - buffer[++i & 511] += (t - last_t) % 3294638521U; + last_td = t - last_t; + buffer[++i & 511] += last_td % 3294638521U; if (last_i && i - last_i > 4 || i - last_i > 64 || TEST && i - last_i > 8) break; } |