38 lines
1.3 KiB
C
38 lines
1.3 KiB
C
/* 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 "xoshiro256.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-poi32 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 u64 rotl(const u64 x, i32 k) {
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return (x << k) | (x>>(64 - k));
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}
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u64 xoshiro256plusplus_next(void* _state) {
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xoshiro256_state* state=_state;
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const u64 result=rotl(state->s[0] + state->s[3], 23) + state->s[0];
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const u64 t=state->s[1] << 17;
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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], 45);
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return result;
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}
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