请问主页漂浮广告的代码。

<div id="ad" style="position:absolute"><a href=http://www.sunsprite.net target="_blank"><img src="img01.gif" border="0"></a></div>
<script>
var x = 50,y = 60
var xin = true, yin = true
var step = 1
var delay = 10
var obj=document.getElementById("ad")
function floatAD() {
var L=T=0
var R= document.body.clientWidth-obj.offsetWidth
var B = document.body.clientHeight-obj.offsetHeight
obj.style.left = x + document.body.scrollLeft
obj.style.top = y + document.body.scrollTop
x = x + step*(xin?1:-1)
if (x < L) { xin = true; x = L}
if (x > R){ xin = false; x = R}
y = y + step*(yin?1:-1)
if (y < T) { yin = true; y = T }
if (y > B) { yin = false; y = B }
}
var itl= setInterval("floatAD()