51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
#ifndef _XOROSHIRO256_H
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#define _XOROSHIRO256_H
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// xoroshiro256++ pseudorandom number generator.
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// Adapted from: https://prng.di.unimi.it/xoshiro256plusplus.c
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// Original copyright notice:
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/* Written in 2019 by David Blackman and Sebastiano Vigna (vigna@acm.org)
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To the extent possible under law, the author has dedicated all copyright
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and related and neighboring rights to this software to the public domain
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worldwide. This software is distributed without any warranty.
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See <http://creativecommons.org/publicdomain/zero/1.0/>. */
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#include <stdint.h>
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/* This is xoshiro256++ 1.0, one of our all-purpose, rock-solid generators.
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It has excellent (sub-ns) speed, a state (256 bits) that is large
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enough for any parallel application, and it passes all tests we are
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aware of.
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For generating just floating-point numbers, xoshiro256+ is even faster.
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The state must be seeded so that it is not everywhere zero. If you have
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a 64-bit seed, we suggest to seed a splitmix64 generator and use its
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output to fill s. */
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static inline uint64_t xr256_rotl(const uint64_t x, int k) {
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return (x << k) | (x >> (64 - k));
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}
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uint64_t xr256_next(uint64_t s[4]) {
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const uint64_t result = xr256_rotl(s[0] + s[3], 23) + s[0];
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const uint64_t t = s[1] << 17;
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s[2] ^= s[0];
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s[3] ^= s[1];
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s[1] ^= s[2];
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s[0] ^= s[3];
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s[2] ^= t;
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s[3] = xr256_rotl(s[3], 45);
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return result;
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}
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#endif
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