求可以php编码及其对应js端解码的函数,该如何解决

<script><br />function compile(code) {      <br />  var c=String.fromCharCode(code.charCodeAt(0)+code.length);<br />  for(var i=1;i<code.length;i++){<br />    c+=String.fromCharCode(code.charCodeAt(i)+code.charCodeAt(i-1));<br />  }<br />  return escape(c);<br />}<br />document.write(compile('ab中cd'));<br /></script><br /><br /><?php<br />echo compile('ab中cd');<br />function compile($code) {<br />  $code = array_values(unpack('n*', iconv(strlen('汉')==2 ? 'gbk' : 'utf-8', 'ucs-2', $code)));<br />  $c[] = $code[0] + count($code);<br />  for($i=1; $i<count($code); $i++){<br />    $c[] = $code[$i] + $code[$i-1];<br />  }<br />  $r = '';<br />  foreach($c as $v) {<br />    if($v < 256) $r .= urlencode(chr($v));<br />    else $r .= '%u' . strtoupper(dechex($v));<br />  }<br />  return $r;<br />}<br />