PseudoRandom.cc

// Copyright (c) 2013 by István Váradi
 
// This file is part of VSCPL, a simple cross-platform utility library
 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
 
// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
//    this list of conditions and the following disclaimer in the documentation
//    and/or other materials provided with the distribution.
 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
// The views and conclusions contained in the software and documentation are those
// of the authors and should not be interpreted as representing official policies,
// either expressed or implied, of the FreeBSD Project.
 
//------------------------------------------------------------------------------
 
#include "PseudoRandom.h"
 
//------------------------------------------------------------------------------
 
using hu::varadiistvan::scpl::PseudoRandom;
 
//------------------------------------------------------------------------------
 
void PseudoRandom::initialize(uint32_t seed)
{
    vector[0] = seed;
    for(size_t i = 1; i<vectorSize-3; ++i) {
        int32_t x = (static_cast<long long>(16807) *
                     static_cast<long long>(vector[i-1])) % 2147483647;
        if (x<0) x += 2147483647;
        vector[i] = x;
    }
    for(size_t i = vectorSize - 3; i<vectorSize; ++i) {
        vector[i] = vector[i-31];
    }
 
    nextIndex = 0;
 
    for(size_t i = vectorSize; i<numDiscarded; ++i) {
        next();
    }
}
 
//------------------------------------------------------------------------------
 
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