/* * Copyright 2017 Timothy Arceri * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * */ #if defined(__linux__) #include #include #else #include #endif #include "rand_xor.h" /* Super fast random number generator. * * This rand_xorshift128plus function by Sebastiano Vigna belongs * to the public domain. */ uint64_t rand_xorshift128plus(uint64_t *seed) { uint64_t *s = seed; uint64_t s1 = s[0]; const uint64_t s0 = s[1]; s[0] = s0; s1 ^= s1 << 23; s[1] = s1 ^ s0 ^ (s1 >> 18) ^ (s0 >> 5); return s[1] + s0; } void s_rand_xorshift128plus(uint64_t *seed, bool randomised_seed) { if (!randomised_seed) goto fixed_seed; #if defined(__linux__) int fd = open("/dev/urandom", O_RDONLY); if (fd < 0) goto fixed_seed; size_t seed_size = sizeof(uint64_t) * 2; if (read(fd, seed, seed_size) != seed_size) { close(fd); goto fixed_seed; } close(fd); return; #else seed[0] = 0x3bffb83978e24f88; seed[1] = time(NULL); return; #endif fixed_seed: /* Fallback to a fixed seed */ seed[0] = 0x3bffb83978e24f88; seed[1] = 0x9238d5d56c71cd35; }