function pageup(){

		if(offset+5>max_num){
			offset=max_num;
			return;
		}
		offset = offset+5;

		paging();
	}

	function page(){
		offset = max_num;
		paging();
	}

	function pagedown(){

		if(offset-5<1){
			return;
		}
		offset = offset-5;

		paging();
	}

	function paging(){


		var i;
		for(i=0;i<5;i++){
			if(!wordlist[offset-i]){
				ajaxrequest();
				break;
			}
		}

		if(i==5){
			show();
		}
	}

	// ajax�ʐM
	function createObject() {
		var request_type;
		var browser = navigator.appName;
		if(browser == "Microsoft Internet Explorer"){
			request_type = new ActiveXObject("Microsoft.XMLHTTP");
		}else{
			request_type = new XMLHttpRequest();
		}
			return request_type;
	}
	var http = createObject();
	function ajaxrequest(){
		var filename = "words.php?os=" + String(max_num -offset);
		http.open('get', filename);
		http.onreadystatechange = displayData;
		http.send(null);
	}

	function displayData(){
		if(http.readyState == 4){
			if(http.responseXML){
				setMarker(http.responseXML);
			}
		}
	}

	function setMarker(xmlobj){
		word = xmlobj.getElementsByTagName('word').length;
		for(i=0;i<word;i++){
			no = xmlobj.getElementsByTagName('order')[i].firstChild.data;
			kanji = xmlobj.getElementsByTagName('kanji')[i].firstChild.data;
			yomi = xmlobj.getElementsByTagName('yomi')[i].firstChild.data;

			wordlist[no] = new wordsSet(kanji,yomi);

		}
		show();
	}

	function show(){
		for(i=0;i<5;i++){
			getElem("wlo"+String(i+1)).innerHTML = (offset-i)<1 || (offset-i)>max_num ? "&nbsp;" :offset-i;
			getElem("wlk"+String(i+1)).innerHTML = wordlist[offset-i] && wordlist[offset-i].kanji ? wordlist[offset-i].kanji : "&nbsp;";
			getElem("wly"+String(i+1)).innerHTML = wordlist[offset-i] && wordlist[offset-i].yomi ? wordlist[offset-i].yomi : "&nbsp;";
		}
	}

	var wordsSet = function (kanji,yomi){
		this.kanji=kanji;
		this.yomi=yomi;
	};

	evtLtn(window,"load",function(){
		getElem("pageup").onclick= function(){pageup();return false;};
		getElem("page").onclick= function(){page();return false;};
		getElem("pagedown").onclick= function(){pagedown();return false;};
	});