哪位高手能给个关于base62解码的例子？

<?php<br />
function base62($x){<br />
$show = '';<br />
while($x > 0){<br />
$s = $x % 62;<br />
if ($s > 35) {<br />
$s = chr($s+61);<br />
} elseif ($s > 9 && $s<=35) {<br />
$s = chr($s + 55);<br />
}<br />
$show .= $s;<br />
$x = floor($x/62);<br />
}<br />
return $show;<br />
}<br />
function urlShort($url)<br />
{<br />
$url = crc32($url);<br />
$result = sprintf("%u", $url);<br />
return base62($result);<br />
}<br />
echo urlShort("http://www.baidu.com");<br />
?>