static uint32_t get_generic_seed(void) { uint8_t tmp[120]; struct AVSHA *sha = (void*)tmp; clock_t last_t = 0; 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 (;;) { clock_t t = clock(); 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; } if(TEST) buffer[0] = buffer[1] = 0; av_sha_init(sha, 160); av_sha_update(sha, (const uint8_t *)buffer, sizeof(buffer)); av_sha_final(sha, digest); return AV_RB32(digest) + AV_RB32(digest + 16); }