mersenne twister implementation rather than mono's RNG
This commit is contained in:
Chris Forbes
157
OpenRA.FileFormats/Thirdparty/Random.cs
vendored
157
OpenRA.FileFormats/Thirdparty/Random.cs
vendored
@@ -1,139 +1,50 @@
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//
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// System.Random.cs
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//
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// Authors:
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// Bob Smith (bob@thestuff.net)
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// Ben Maurer (bmaurer@users.sourceforge.net)
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//
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// (C) 2001 Bob Smith. http://www.thestuff.net
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// (C) 2003 Ben Maurer
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//
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//
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// Copyright (C) 2004 Novell, Inc (http://www.novell.com)
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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//
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using System;
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namespace OpenRA.Thirdparty
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{
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[Serializable]
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// quick & dirty Mersenne Twister [MT19937] implementation
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public class Random
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{
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const int MBIG = int.MaxValue;
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const int MSEED = 161803398;
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const int MZ = 0;
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int[] mt = new int[624];
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int index = 0;
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int inext, inextp;
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int [] SeedArray = new int [56];
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public Random() : this(Environment.TickCount) { }
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public Random ()
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: this (Environment.TickCount)
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public Random(int seed)
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{
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mt[0] = seed;
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for (var i = 1; i < mt.Length; i++)
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mt[i] = 1812433253 * (mt[i - 1] ^ (mt[i - 1] >> 30)) + i;
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}
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public Random (int Seed)
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public int Next()
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{
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int ii;
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int mj, mk;
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if (index == 0) Generate();
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// Numerical Recipes in C online @ http://www.library.cornell.edu/nr/bookcpdf/c7-1.pdf
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mj = MSEED - Math.Abs (Seed);
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SeedArray [55] = mj;
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mk = 1;
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for (int i = 1; i < 55; i++) { // [1, 55] is special (Knuth)
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ii = (21 * i) % 55;
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SeedArray [ii] = mk;
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mk = mj - mk;
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if (mk < 0)
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mk += MBIG;
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mj = SeedArray [ii];
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var y = mt[index];
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y ^= (y >> 11);
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y ^= (int)((y << 7) & 2636928640);
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y ^= (int)((y << 15) & 4022730752);
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y ^= y >> 18;
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index = (index + 1) % 624;
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return y;
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}
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public int Next(int low, int high) { return low + Next() % (high - low); }
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public int Next(int high) { return Next() % high; }
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public double NextDouble() { return (uint)Next() / (double)uint.MaxValue; }
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void Generate()
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{
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for (var i = 0; i < mt.Length; i++)
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{
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var y = (mt[i] & int.MinValue) | (mt[(i + 1) % 624] & int.MaxValue);
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mt[i] = mt[(i + 397) % 624] ^ (y >> 1);
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if ((y & 1) == 1)
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mt[i] = (int)(mt[i] ^ 2567483615);
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}
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for (int k = 1; k < 5; k++) {
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for (int i = 1; i < 56; i++) {
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SeedArray [i] -= SeedArray [1 + (i + 30) % 55];
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if (SeedArray [i] < 0)
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SeedArray [i] += MBIG;
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}
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}
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inext = 0;
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inextp = 31;
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}
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protected virtual double Sample ()
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{
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int retVal;
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if (++inext >= 56) inext = 1;
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if (++inextp >= 56) inextp = 1;
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retVal = SeedArray [inext] - SeedArray [inextp];
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if (retVal < 0)
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retVal += MBIG;
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SeedArray [inext] = retVal;
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return retVal * (1.0 / MBIG);
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}
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public virtual int Next ()
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{
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return (int)(Sample () * int.MaxValue);
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}
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public virtual int Next (int maxValue)
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{
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if (maxValue < 0)
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throw new ArgumentOutOfRangeException("Max value is less then min value.");
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return (int)(Sample () * maxValue);
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}
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public virtual int Next (int minValue, int maxValue)
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{
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if (minValue > maxValue)
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throw new ArgumentOutOfRangeException("Min value is greater then max value.");
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uint diff = (uint)(maxValue - minValue);
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if (diff == 0)
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return minValue;
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int result = (int)(Sample () * diff + minValue);
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return ((result != maxValue) ? result : (result - 1));
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}
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public virtual void NextBytes (byte [] buffer)
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{
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if (buffer == null)
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throw new ArgumentNullException ("buffer");
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for (int i = 0; i < buffer.Length; i++) {
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buffer [i] = (byte)(Sample () * (byte.MaxValue + 1));
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}
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}
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public virtual double NextDouble ()
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{
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return this.Sample ();
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}
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}
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}
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