From da73d95bad4736c5e0a6b4b1a811f4dd4525bb4c Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 22 Dec 2016 03:59:03 +0100 Subject: avutil/random_seed: Improve get_generic_seed() with higher precission clock() Tested-by: Thomas Turner Signed-off-by: Michael Niedermayer --- libavutil/random_seed.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'libavutil') diff --git a/libavutil/random_seed.c b/libavutil/random_seed.c index 79bc7af..179fb23 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; } -- cgit v1.1