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