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random.c
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random.c
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// https://prng.di.unimi.it/splitmix64.c
/* Written in 2015 by Sebastiano Vigna ([email protected])
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>
/* This is a fixed-increment version of Java 8's SplittableRandom generator
See http://dx.doi.org/10.1145/2714064.2660195 and
http://docs.oracle.com/javase/8/docs/api/java/util/SplittableRandom.html
It is a very fast generator passing BigCrush, and it can be useful if
for some reason you absolutely want 64 bits of state. */
static uint64_t x = 0x1234567890abcdef; /* The state can be seeded with any value. */
uint64_t splitmix64() {
uint64_t z = (x += 0x9e3779b97f4a7c15);
z = (z ^ (z >> 30)) * 0xbf58476d1ce4e5b9;
z = (z ^ (z >> 27)) * 0x94d049bb133111eb;
return z ^ (z >> 31);
}
// https://prng.di.unimi.it/xoshiro256plus.c
/* Written in 2018 by David Blackman and Sebastiano Vigna ([email protected])
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/>. */
/* This is xoshiro256+ 1.0, our best and fastest generator for floating-point
numbers. We suggest to use its upper bits for floating-point
generation, as it is slightly faster than xoshiro256++/xoshiro256**. It
passes all tests we are aware of except for the lowest three bits,
which might fail linearity tests (and just those), so if low linear
complexity is not considered an issue (as it is usually the case) it
can be used to generate 64-bit outputs, too.
We suggest to use a sign test to extract a random Boolean value, and
right shifts to extract subsets of bits.
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));
}
static uint64_t s[4] = {1,2,3,4};
uint64_t xoshiro256plus(void) {
const uint64_t result = s[0] + s[3];
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;
}
/* This is the jump function for the generator. It is equivalent
to 2^128 calls to xoshiro256plus(); it can be used to generate 2^128
non-overlapping subsequences for parallel computations. */
void jump(void) {
static const uint64_t JUMP[] = { 0x180ec6d33cfd0aba, 0xd5a61266f0c9392c, 0xa9582618e03fc9aa, 0x39abdc4529b1661c };
uint64_t s0 = 0;
uint64_t s1 = 0;
uint64_t s2 = 0;
uint64_t s3 = 0;
for(int i = 0; i < sizeof JUMP / sizeof *JUMP; i++)
for(int b = 0; b < 64; b++) {
if (JUMP[i] & UINT64_C(1) << b) {
s0 ^= s[0];
s1 ^= s[1];
s2 ^= s[2];
s3 ^= s[3];
}
xoshiro256plus();
}
s[0] = s0;
s[1] = s1;
s[2] = s2;
s[3] = s3;
}
/* This is the long-jump function for the generator. It is equivalent to
2^192 calls to xoshiro256plus(); it can be used to generate 2^64 starting points,
from each of which jump() will generate 2^64 non-overlapping
subsequences for parallel distributed computations. */
void long_jump(void) {
static const uint64_t LONG_JUMP[] = { 0x76e15d3efefdcbbf, 0xc5004e441c522fb3, 0x77710069854ee241, 0x39109bb02acbe635 };
uint64_t s0 = 0;
uint64_t s1 = 0;
uint64_t s2 = 0;
uint64_t s3 = 0;
for(int i = 0; i < sizeof LONG_JUMP / sizeof *LONG_JUMP; i++)
for(int b = 0; b < 64; b++) {
if (LONG_JUMP[i] & UINT64_C(1) << b) {
s0 ^= s[0];
s1 ^= s[1];
s2 ^= s[2];
s3 ^= s[3];
}
xoshiro256plus();
}
s[0] = s0;
s[1] = s1;
s[2] = s2;
s[3] = s3;
}
////////////////////////////////////////////////////////////////////////////////
void seed(uint64_t v) {
x = v;
s[0] = splitmix64();
s[1] = splitmix64();
s[2] = splitmix64();
s[3] = splitmix64();
}