(function($){
	$.fn.extend({
		rollList:function(option){
			option=$.extend({
				direction:"up",
				step:1,
				time:23
			},option);
			var step_coe,scroll_coe,score_coe;
			if(option.direction=="up")
			{
				step_coe=1;
				scroll_coe=1;
				score_coe=1;
			}else
			{
				step_coe=-1;
				scroll_coe=-1;
				score_coe=0;
			}
			return this.each(function(){
				var $this=$(this);
				var _this=this;
				var itemHeight;
				var temp=$("<div></div>");
				var tempi=0;
				$this.css("overflow","hidden").children()
					.appendTo(temp);
				$this.append(temp.clone(true)).append(temp);
				itemHeight=$this.children();
				itemHeight=itemHeight.eq(1).offset().top-itemHeight.eq(0).offset().top;
				while($this.children(":last").offset().top-$this.offset().top<=$this.height())
				{
					$this.append(temp.clone(true));
					tempi++;
					if(tempi>20)
					    break;
			    }
				var roll;
				this.scrollTop=itemHeight*(1-score_coe);
				roll=function (){
					temp=setInterval(function(){
						try{
						    if(_this.scrollTop*scroll_coe>=itemHeight*score_coe)
						    {	
							    _this.scrollTop=(_this.scrollTop-itemHeight)*scroll_coe;
						    }
						    _this.scrollTop+=option.step*step_coe;
						}catch(e){}
						
					},option.time);
				}
				$this.hover(function(){
					clearInterval(temp);
				},function(){
					roll();	
				});
				roll();
			});
		}		
	})
}(jQuery));