Mersenne Twister

MersenneTwister
http://www.devslash.com/?p=97
@author paq

by paq 28 Apr 2010

Embed

/**
 * Copyright paq ( http://wonderfl.net/user/paq )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/m22B
 */

package 
{
	import com.bit101.components.InputText;
	import com.bit101.components.Label;
	import com.bit101.components.PushButton;
	import com.bit101.components.Text;
	import flash.display.Sprite;
	import flash.events.Event;
	import flash.events.MouseEvent;
	
	/**
	 * MersenneTwister
	 * http://www.devslash.com/?p=97
	 * @author paq
	 */
	[SWF(width=465, height=465, backgroundColor=0xFFFFFF, frameRate=24)]
	public class Mersenne extends Sprite 
	{
		public function Mersenne():void 
		{
			__init();
		}
		
		private var _input:InputText;
		private var _result:Text;
		
		private function __init():void 
		{
			new Label(this, 12, 13, "seed:");
			new PushButton(this, 150, 12, "generate", __seedButton_push__);
			_input = new InputText(this, 42, 12, "1");
			_input.restrict = "0123456789";
			_input.height = 20;
			_result = new Text(this, 12, 48);
			_result.setSize(441, 405);
			_result.editable = false;
		}
		
		private function __seedButton_push__($event:MouseEvent):void
		{
			MersenneTwister.initialiseGenerator(int(_input.text));
			_result.text = MersenneTwister.generateRandomNum() + "\n" + _result.text;
		}
	}
}

class MersenneTwister
{
	private static var MT:Array = new Array();
	private static var y:Number, z:Number = 0;

	public static function initialiseGenerator(seed:Number):void
	{
		MT[0] = seed;
		for(var i:int=1; i<623; i++)
			MT[i] = ((0x10dcd * MT[i-1]) + 1)& 0xFFFFFFFF
	}
	
	private static function generateNumbers():void
	{
		z = 0;
		for(var i:int=0; i<623; i++)
		{
			y = 0x80000000 & MT[i] + 0x7FFFFFFF & (MT[(i+1)%624]);
			if((y % 2) == 0)
				MT[i] = MT[(i + 397) % 624] ^ (y >> 1);
			else
				MT[i] = MT[(i + 397) % 624] ^ (y >> 1) ^ 0x9908B0DF;
		}
	}
	
	public static function extractNumber(i:Number):Number
	{
		y = MT[i];
		y ^= (y >> 11);
		y ^= (y << 7) & 0x9d2c5680;
		y ^= (y << 15) & 0xefc60000;
		y ^= (y >> 18);
		return y;
	}

	public static function generateRandomNum():Number
	{
		if(z >= 623)
			generateNumbers();
		return extractNumber(z++);
	}
}