encode/decode string

<?php

function randucode($txt) {
    $x=56780; $out="";
    for($i=0;$i<strlen($txt);$i++) {
        $x=((($x*65539)+0) ^ 0x7FFFFFFF) & 0xFFFFFFFF;
        $r=($x ^ ($x >> 16))& 0x3F;
        $s=ord($txt[$i]);
        if($s>=46 && $s<=127) {
            $s=($s ^ $r);
            if($s<46 or $s>=127) $s=($s ^ $r);
        }
        $out.=chr($s);
    }
    return $out;
}
function encode($txt) {
    return str_replace(array("?","&","/","="),array("(",")","*",","),randucode($txt));
}
function decode($txt) {
    return randucode(str_replace(array("(",")","*",","),array("?","&","/","="),$txt));
}

$c=encode('/?id=12&link=http://example.com/?id=123&p=param');

var_dump(encode("/?id=12&link=http://example.com/?id=123&p=param"));
var_dump(decode(encode("/?id=12&link=http://example.com/?id=123&p=param")));