88 lines
1.8 KiB
C#
88 lines
1.8 KiB
C#
#region Copyright & License Information
|
|
/*
|
|
* Copyright 2007-2020 The OpenRA Developers (see AUTHORS)
|
|
* This file is part of OpenRA, which is free software. It is made
|
|
* available to you under the terms of the GNU General Public License
|
|
* as published by the Free Software Foundation, either version 3 of
|
|
* the License, or (at your option) any later version. For more
|
|
* information, see COPYING.
|
|
*/
|
|
#endregion
|
|
|
|
using System;
|
|
|
|
namespace OpenRA.Support
|
|
{
|
|
// Quick & dirty Mersenne Twister [MT19937] implementation
|
|
public class MersenneTwister
|
|
{
|
|
readonly uint[] mt = new uint[624];
|
|
int index = 0;
|
|
|
|
public int Last;
|
|
public int TotalCount = 0;
|
|
|
|
public MersenneTwister()
|
|
: this(Environment.TickCount) { }
|
|
|
|
public MersenneTwister(int seed)
|
|
{
|
|
mt[0] = (uint)seed;
|
|
for (var i = 1u; i < mt.Length; i++)
|
|
mt[i] = 1812433253u * (mt[i - 1] ^ (mt[i - 1] >> 30)) + i;
|
|
}
|
|
|
|
public int Next()
|
|
{
|
|
if (index == 0) Generate();
|
|
|
|
var y = mt[index];
|
|
y ^= y >> 11;
|
|
y ^= (y << 7) & 2636928640;
|
|
y ^= (y << 15) & 4022730752;
|
|
y ^= y >> 18;
|
|
|
|
index = (index + 1) % 624;
|
|
TotalCount++;
|
|
Last = (int)(y % int.MaxValue);
|
|
return Last;
|
|
}
|
|
|
|
public int Next(int low, int high)
|
|
{
|
|
if (high < low)
|
|
throw new ArgumentOutOfRangeException("high", "Maximum value is less than the minimum value.");
|
|
|
|
var diff = high - low;
|
|
if (diff <= 1)
|
|
return low;
|
|
|
|
return low + Next() % diff;
|
|
}
|
|
|
|
public int Next(int high)
|
|
{
|
|
return Next(0, high);
|
|
}
|
|
|
|
public float NextFloat()
|
|
{
|
|
return Math.Abs(Next() / (float)0x7fffffff);
|
|
}
|
|
|
|
void Generate()
|
|
{
|
|
unchecked
|
|
{
|
|
for (var i = 0u; i < mt.Length; i++)
|
|
{
|
|
var y = (mt[i] & 0x80000000) | (mt[(i + 1) % 624] & 0x7fffffff);
|
|
mt[i] = mt[(i + 397u) % 624u] ^ (y >> 1);
|
|
if ((y & 1) == 1)
|
|
mt[i] = mt[i] ^ 2567483615;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|