46 lines
1.3 KiB
C
46 lines
1.3 KiB
C
/* Written in 2018 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 "xoshiro128.h"
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/* This is xoshiro128** 1.1, one of our 32-bit all-purpose, rock-solid
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generators. It has excellent speed, a state size (128 bits) that is
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large enough for mild parallelism, and it passes all tests we are aware
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of.
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Note that version 1.0 had mistakenly state->s[0] instead of state->s[1] as state
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word passed to the scrambler.
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For generating just single-precision (i.e., 32-bit) floating-point
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numbers, xoshiro128+ is even faster.
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The state must be seeded so that it is not everywhere zero. */
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static inline u32 rotl(const u32 x, i32 k) {
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return (x << k) | (x >> (32 - k));
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}
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u32 xoshiro128starstar_next(void* _state){
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xoshiro128_state* state=_state;
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const u32 result = rotl(state->s[1] * 5, 7) * 9;
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const u32 t = state->s[1] << 9;
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state->s[2] ^= state->s[0];
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state->s[3] ^= state->s[1];
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state->s[1] ^= state->s[2];
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state->s[0] ^= state->s[3];
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state->s[2] ^= t;
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state->s[3] = rotl(state->s[3], 11);
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return result;
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}
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