forked from: forked from: [最適化 Tips] Modulo vs Logical AND

/**
 * Copyright onedayitwillmake ( http://wonderfl.net/user/onedayitwillmake )
 * MIT License ( http://www.opensource.org/licenses/mit-license.php )
 * Downloaded from: http://wonderfl.net/c/q1As
 */

// forked from onedayitwillmake's forked from: [最適化 Tips] Faster Math.sqrt?
// forked from muta244's [最適化 Tips] 変数名の長さによる処理速度の違い
package {

import flash.display.*;
import flash.events.*;
import flash.text.*;
import flash.utils.*;

public class Main extends Sprite
{
    static private const _NUM_TIMES    :uint = 1000000;
    static private var _isEven         :Boolean;
    
    private function _init():void
    {
        _debug(
            "Math.sqrt vs custom function " + _NUM_TIMES + " cycles.\n"
        );
        
        _measure("Empty loop", function ():void
        {
            for (var i:uint = 0; i < _NUM_TIMES; i++) {
                
            }
        });
        
        _measure("isEven with Modulo ( % )", function ():void
        {
            for (var i:uint = 0; i < _NUM_TIMES; i++) {
                _isEven = (i % 2) == 0;
            }
        });
        
        _measure("isEven with AND ( & )", function ():void
        {
            for (var i:uint = 0; i < _NUM_TIMES; i++) {
                 _isEven = (i & 1) == 0;
            }
        });
        
  
        
     
        
        _debug("\n Using Logical AND is ~1000% faster than modulo.");
    }
    
    private var _field:TextField;
    private var _time:uint;
    
    public function Main():void
    {
        _setup();
        _init();
    }
    
    private function _measure(title:String, func:Function, ...params):void
    {
        _time = getTimer();
        func.apply(null, params);
        _time = getTimer() - _time;
        
        _debug("[ " + title + " ] --> " + _time + " ms");
    }
    
    private function _debug(log:String):void
    {
        _field.appendText(log + "\n");
    }
    
    private function _setup():void
    {
        _field = new TextField();
        _field.width = stage.stageWidth - 40;
        _field.height = stage.stageHeight - 60;
        _field.x = 20;
        _field.y = 60;
        
        var format:TextFormat = _field.defaultTextFormat;
        format.font = "_sans";
        _field.defaultTextFormat = format;
        
        addChild(_field);
        
        var button:Sprite = new Sprite();
        button.graphics.lineStyle(1, 0xBBBBBB);
        button.graphics.beginFill(0xEEEEEE);
        button.graphics.drawRoundRect(0, 0, 100, 20, 5, 5);
        button.graphics.endFill();
        
        addChild(button);
        
        button.x = 20;
        button.y = 20;
        button.mouseChildren = false;
        button.buttonMode = true;
        
        var field:TextField = new TextField();
        field.width = 100;
        field.height = 20;
        field.htmlText = "<p align='center'><font face='_sans'>Test Again</span></p>";
        
        button.addChild(field);
        
        button.addEventListener(MouseEvent.CLICK, function ():void
        {
            _field.text = "";
            _init();
        });
    }
    
    
    
    public static function FSQRT(val:Number):Number
    {
	var thres:Number = 0.002;
	var b:Number = val * 0.25;
	var a:Number;
	var c:Number;
	
	do
	{
			c = val / b;
			b = (b + c) * 0.5;
			a = b - c;
			if (a < 0) a = -a;
	}
	while (a > thres);
	
	return b;
    }

}

}