X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=src%2Fxoshiro.c;fp=src%2Fxoshiro.c;h=c05e9405a2e7b33d191d1ba5b4dbda60aee72714;hb=ea20fcfcded669ce8fbbda3a1f93f354ed254603;hp=0000000000000000000000000000000000000000;hpb=ac63b6adaf29c4143f9e106039011b9ebeb96b93;p=meshlink

diff --git a/src/xoshiro.c b/src/xoshiro.c
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+++ b/src/xoshiro.c
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+/*  Written in 2018 by David Blackman and Sebastiano Vigna (vigna@acm.org)
+
+To the extent possible under law, the author has dedicated all copyright
+and related and neighboring rights to this software to the public domain
+worldwide. This software is distributed without any warranty.
+
+See <http://creativecommons.org/publicdomain/zero/1.0/>. */
+
+#include <stdint.h>
+#include "xoshiro.h"
+
+/* This is xoshiro256** 1.0, one of our all-purpose, rock-solid
+   generators. It has excellent (sub-ns) speed, a state (256 bits) that is
+   large enough for any parallel application, and it passes all tests we
+   are aware of.
+
+   For generating just floating-point numbers, xoshiro256+ is even faster.
+
+   The state must be seeded so that it is not everywhere zero. If you have
+   a 64-bit seed, we suggest to seed a splitmix64 generator and use its
+   output to fill s. */
+
+static inline uint64_t rotl(const uint64_t x, int k) {
+	return (x << k) | (x >> (64 - k));
+}
+
+uint64_t xoshiro(uint64_t s[4]) {
+	const uint64_t result = rotl(s[1] * 5, 7) * 9;
+
+	const uint64_t t = s[1] << 17;
+
+	s[2] ^= s[0];
+	s[3] ^= s[1];
+	s[1] ^= s[2];
+	s[0] ^= s[3];
+
+	s[2] ^= t;
+
+	s[3] = rotl(s[3], 45);
+
+	return result;
+}