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#pragma once
/**
@file
@brief XorShift
@author MITSUNARI Shigeo(@herumi)
@author MITSUNARI Shigeo
*/
#include <cybozu/inttype.hpp>
#include <assert.h>
namespace cybozu {
namespace xorshift_local {
/*
U is uint32_t or uint64_t
*/
template<class U, class Gen>
void read_local(void *p, size_t n, Gen& gen, U (Gen::*f)())
{
uint8_t *dst = static_cast<uint8_t*>(p);
const size_t uSize = sizeof(U);
assert(uSize == 4 || uSize == 8);
union ua {
U u;
uint8_t a[uSize];
};
while (n >= uSize) {
ua ua;
ua.u = (gen.*f)();
for (size_t i = 0; i < uSize; i++) {
dst[i] = ua.a[i];
}
dst += uSize;
n -= uSize;
}
assert(n < uSize);
if (n > 0) {
ua ua;
ua.u = (gen.*f)();
for (size_t i = 0; i < n; i++) {
dst[i] = ua.a[i];
}
}
}
} // xorshift_local
class XorShift {
uint32_t x_, y_, z_, w_;
public:
explicit XorShift(uint32_t x = 0, uint32_t y = 0, uint32_t z = 0, uint32_t w = 0)
{
init(x, y, z, w);
}
void init(uint32_t x = 0, uint32_t y = 0, uint32_t z = 0, uint32_t w = 0)
{
x_ = x ? x : 123456789;
y_ = y ? y : 362436069;
z_ = z ? z : 521288629;
w_ = w ? w : 88675123;
}
uint32_t get32()
{
unsigned int t = x_ ^ (x_ << 11);
x_ = y_; y_ = z_; z_ = w_;
return w_ = (w_ ^ (w_ >> 19)) ^ (t ^ (t >> 8));
}
uint32_t operator()() { return get32(); }
uint64_t get64()
{
uint32_t a = get32();
uint32_t b = get32();
return (uint64_t(a) << 32) | b;
}
template<class T>
void read(bool *pb, T *p, size_t n)
{
xorshift_local::read_local(p, n * sizeof(T), *this, &XorShift::get32);
*pb = true;
}
template<class T>
size_t read(T *p, size_t n)
{
bool b;
read(&b, p, n);
(void)b;
return n;
}
};
// see http://xorshift.di.unimi.it/xorshift128plus.c
class XorShift128Plus {
uint64_t s_[2];
static const uint64_t seed0 = 123456789;
static const uint64_t seed1 = 987654321;
public:
explicit XorShift128Plus(uint64_t s0 = seed0, uint64_t s1 = seed1)
{
init(s0, s1);
}
void init(uint64_t s0 = seed0, uint64_t s1 = seed1)
{
s_[0] = s0;
s_[1] = s1;
}
uint32_t get32()
{
return static_cast<uint32_t>(get64());
}
uint64_t operator()() { return get64(); }
uint64_t get64()
{
uint64_t s1 = s_[0];
const uint64_t s0 = s_[1];
s_[0] = s0;
s1 ^= s1 << 23;
s_[1] = s1 ^ s0 ^ (s1 >> 18) ^ (s0 >> 5);
return s_[1] + s0;
}
template<class T>
void read(bool *pb, T *p, size_t n)
{
xorshift_local::read_local(p, n * sizeof(T), *this, &XorShift128Plus::get64);
*pb = true;
}
template<class T>
size_t read(T *p, size_t n)
{
bool b;
read(&b, p, n);
(void)b;
return n;
}
};
// see http://xoroshiro.di.unimi.it/xoroshiro128plus.c
class Xoroshiro128Plus {
uint64_t s_[2];
static const uint64_t seed0 = 123456789;
static const uint64_t seed1 = 987654321;
uint64_t rotl(uint64_t x, unsigned int k) const
{
return (x << k) | (x >> (64 - k));
}
public:
explicit Xoroshiro128Plus(uint64_t s0 = seed0, uint64_t s1 = seed1)
{
init(s0, s1);
}
void init(uint64_t s0 = seed0, uint64_t s1 = seed1)
{
s_[0] = s0;
s_[1] = s1;
}
uint32_t get32()
{
return static_cast<uint32_t>(get64());
}
uint64_t operator()() { return get64(); }
uint64_t get64()
{
uint64_t s0 = s_[0];
uint64_t s1 = s_[1];
uint64_t result = s0 + s1;
s1 ^= s0;
s_[0] = rotl(s0, 55) ^ s1 ^ (s1 << 14);
s_[1] = rotl(s1, 36);
return result;
}
template<class T>
void read(bool *pb, T *p, size_t n)
{
xorshift_local::read_local(p, n * sizeof(T), *this, &Xoroshiro128Plus::get64);
*pb = true;
}
template<class T>
size_t read(T *p, size_t n)
{
bool b;
read(&b, p, n);
(void)b;
return n;
}
};
} // cybozu
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