util/random/mersenne32.h


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#pragma once
 
#include <util/system/defaults.h>
 
class IInputStream;
 
namespace NPrivate { 
    class TMersenne32 { 
        static constexpr int N = 624;
 
    public: 
        inline TMersenne32(ui32 s = 19650218UL) noexcept
            : mti(N + 1) 
        { 
            InitGenRand(s); 
        } 
 
        inline TMersenne32(const ui32* init_key, size_t key_length) noexcept
            : mti(N + 1) 
        { 
            InitByArray(init_key, key_length); 
        } 
 
        TMersenne32(IInputStream& input);
 
        inline ui32 GenRand() noexcept {
            if (mti >= N) { 
                InitNext(); 
            } 
 
            ui32 y = mt[mti++]; 
 
            y ^= (y >> 11); 
            y ^= (y << 7) & 0x9d2c5680UL; 
            y ^= (y << 15) & 0xefc60000UL; 
            y ^= (y >> 18); 
 
            return y; 
        } 
 
    private: 
        void InitNext() noexcept;
        void InitGenRand(ui32 s) noexcept;
        void InitByArray(const ui32* init_key, size_t key_length) noexcept;
 
    private: 
        ui32 mt[N]; 
        int mti; 
    }; 
}