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#pragma once
/**
    @file
    @brief XorShift

    @author MITSUNARI Shigeo(@herumi)
    @author MITSUNARI Shigeo
*/
#include <cybozu/inttype.hpp>

namespace cybozu {

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(T *x, size_t n)
    {
        const size_t size = sizeof(T) * n;
        uint8_t *p8 = static_cast<uint8_t*>(x);
        for (size_t i = 0; i < size; i++) {
            p8[i] = static_cast<uint8_t>(get32());
        }
    }
    void read(uint32_t *x, size_t n)
    {
        for (size_t i = 0; i < n; i++) {
            x[i] = get32();
        }
    }
    void read(uint64_t *x, size_t n)
    {
        for (size_t i = 0; i < n; i++) {
            x[i] = get64();
        }
    }
};

// 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(T *x, size_t n)
    {
        const size_t size = sizeof(T) * n;
        uint8_t *p8 = static_cast<uint8_t*>(x);
        for (size_t i = 0; i < size; i++) {
            p8[i] = static_cast<uint8_t>(get32());
        }
    }
    void read(uint32_t *x, size_t n)
    {
        for (size_t i = 0; i < n; i++) {
            x[i] = get32();
        }
    }
    void read(uint64_t *x, size_t n)
    {
        for (size_t i = 0; i < n; i++) {
            x[i] = get64();
        }
    }
};

// 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(T *x, size_t n)
    {
        const size_t size = sizeof(T) * n;
        uint8_t *p8 = static_cast<uint8_t*>(x);
        for (size_t i = 0; i < size; i++) {
            p8[i] = static_cast<uint8_t>(get32());
        }
    }
    void read(uint32_t *x, size_t n)
    {
        for (size_t i = 0; i < n; i++) {
            x[i] = get32();
        }
    }
    void read(uint64_t *x, size_t n)
    {
        for (size_t i = 0; i < n; i++) {
            x[i] = get64();
        }
    }
};

} // cybozu