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🎥 Command line media player
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C
1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192/* * Implementation of non-cryptographic pseudo-random number * generator algorithm known as xoshiro. * * This file is part of mpv. * * mpv 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. * * mpv 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 mpv. If not, see <http://www.gnu.org/licenses/>. */
#include <stdint.h>
#include <libavutil/random_seed.h>
#include "osdep/threads.h"#include "osdep/timer.h"#include "random.h"
static uint64_t state[4];static mp_static_mutex state_mutex = MP_STATIC_MUTEX_INITIALIZER;
static inline uint64_t rotl_u64(const uint64_t x, const int k){ return (x << k) | (x >> (64 - k));}
static inline uint64_t splitmix64(uint64_t *const x){ uint64_t z = (*x += UINT64_C(0x9e3779b97f4a7c15)); z = (z ^ (z >> 30)) * UINT64_C(0xbf58476d1ce4e5b9); z = (z ^ (z >> 27)) * UINT64_C(0x94d049bb133111eb); return z ^ (z >> 31);}
void mp_rand_seed(uint64_t seed){#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION seed = 42;#endif
if (seed == 0) { uint8_t buf[sizeof(seed)]; if (av_random_bytes(buf, sizeof(buf)) < 0) { seed = mp_raw_time_ns(); } else { memcpy(&seed, buf, sizeof(seed)); } }
mp_mutex_lock(&state_mutex); state[0] = seed; for (int i = 1; i < 4; i++) state[i] = splitmix64(&seed); mp_mutex_unlock(&state_mutex);}
uint64_t mp_rand_next(void){ uint64_t result, t;
mp_mutex_lock(&state_mutex);
result = rotl_u64(state[1] * 5, 7) * 9; t = state[1] << 17;
state[2] ^= state[0]; state[3] ^= state[1]; state[1] ^= state[2]; state[0] ^= state[3]; state[2] ^= t; state[3] = rotl_u64(state[3], 45);
mp_mutex_unlock(&state_mutex);
return result;}
double mp_rand_next_double(void){ return (mp_rand_next() >> 11) * 0x1.0p-53;}