function cdtime(container, targetdate){
	if (!document.getElementById || !document.getElementById(container)) return;
	this.container=document.getElementById(container);
	this.currentTime=new Date();
	this.targetdate=new Date(targetdate);
	this.timesup=false;
	this.updateTime();
}

cdtime.prototype.updateTime=function(){
	var thisobj=this;
	this.currentTime.setSeconds(this.currentTime.getSeconds()+1);
	setTimeout(function(){thisobj.updateTime()}, 1000) //update time every second
}

cdtime.prototype.displaycountdown=function(baseunit, functionref){
	this.baseunit=baseunit;
	this.formatresults=functionref;
	this.showresults();
}

cdtime.prototype.showresults=function(){
	var thisobj=this;

	var timediff=(this.targetdate-this.currentTime)/1000; //difference btw target date and current date, in seconds
	if (timediff<0){ //if time is up
		this.timesup=true;
		this.container.innerHTML=this.formatresults();
		return;
	}
	var oneMinute=60; //minute unit in seconds
	var oneHour=60*60; //hour unit in seconds
	var oneDay=60*60*24; //day unit in seconds
	var dayfield=Math.floor(timediff/oneDay);
	var hourfield=Math.floor((timediff-dayfield*oneDay)/oneHour);
	var minutefield=Math.floor((timediff-dayfield*oneDay-hourfield*oneHour)/oneMinute);
	var secondfield=Math.floor((timediff-dayfield*oneDay-hourfield*oneHour-minutefield*oneMinute));
	if (this.baseunit=="hours"){ //if base unit is hours, set "hourfield" to be topmost level
		hourfield=dayfield*24+hourfield;
		dayfield="n/a";
	}
	else if (this.baseunit=="minutes"){ //if base unit is minutes, set "minutefield" to be topmost level
		minutefield=dayfield*24*60+hourfield*60+minutefield;
		dayfield=hourfield="n/a";
	}
	else if (this.baseunit=="seconds"){ //if base unit is seconds, set "secondfield" to be topmost level
		var secondfield=timediff;
		dayfield=hourfield=minutefield="n/a";
	}
	this.container.innerHTML=this.formatresults(dayfield, hourfield, minutefield, secondfield);
	setTimeout(function(){thisobj.showresults()}, 1000); //update results every second
}

function formatresults(){
	if (this.timesup==false){//if target date/time not yet met
		var displaystring=arguments[0]+"<span>D</span> "+arguments[1]+"<span>H</span> "+arguments[2]+"<span>M</span> "+arguments[3]+"<span>S</span>";
	}
	else{ //else if target date/time met
		var displaystring="EM CURSO";
	}
	return displaystring;
}