Random.cpp

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/*
  ==============================================================================
 
   This file is part of the Water library.
   Copyright (c) 2016 ROLI Ltd.
   Copyright (C) 2017-2022 Filipe Coelho <falktx@falktx.com>
 
   Permission is granted to use this software under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license/
 
   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.
 
   THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
   OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   OF THIS SOFTWARE.
 
  ==============================================================================
*/
 
#include "Random.h"
#include "../misc/Time.h"
 
#include <limits>
 
namespace water {
 
Random::Random (const int64 seedValue) noexcept   : seed (seedValue)
{
}
 
Random::Random()  : seed (1)
{
    setSeedRandomly();
}
 
Random::~Random() noexcept
{
}
 
void Random::setSeed (const int64 newSeed) noexcept
{
    seed = newSeed;
}
 
void Random::combineSeed (const int64 seedValue) noexcept
{
    seed ^= nextInt64() ^ seedValue;
}
 
void Random::setSeedRandomly()
{
    static int64 globalSeed = 0;
 
    combineSeed (globalSeed ^ (int64) (pointer_sized_int) this);
    combineSeed (Time::getMillisecondCounter());
    combineSeed (Time::currentTimeMillis());
    globalSeed ^= seed;
}
 
Random& Random::getSystemRandom() noexcept
{
    static Random sysRand;
    return sysRand;
}
 
//==============================================================================
int Random::nextInt() noexcept
{
    seed = (seed * 0x5deece66dLL + 11) & 0xffffffffffffLL;
 
    return (int) (seed >> 16);
}
 
int Random::nextInt (const int maxValue) noexcept
{
    wassert (maxValue > 0);
    return (int) ((((unsigned int) nextInt()) * (uint64) maxValue) >> 32);
}
 
int64 Random::nextInt64() noexcept
{
    return (((int64) nextInt()) << 32) | (int64) (uint64) (uint32) nextInt();
}
 
bool Random::nextBool() noexcept
{
    return (nextInt() & 0x40000000) != 0;
}
 
float Random::nextFloat() noexcept
{
    return static_cast<uint32> (nextInt()) / (static_cast<float>(std::numeric_limits<uint32>::max()) + 1.5f);
}
 
double Random::nextDouble() noexcept
{
    return static_cast<uint32> (nextInt()) / (static_cast<double>(std::numeric_limits<uint32>::max() + 1.5));
}
 
}