source: xplcommon/src/xplcommon/PseudoRandom.cc@ 27:11b3ec33029d

// Copyright (c) 2013 by István Váradi

// This file is part of libxplcommon, a common utility library for
// development related to X-Plane

// 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 xplcommon::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();
    }
}

//------------------------------------------------------------------------------

// Local Variables:
// mode: C++
// c-basic-offset: 4
// indent-tabs-mode: nil
// End: