Simple serialization format

Serialize.php

<?php

function serialize_uint($x) {
    for ($r = ''; $x > 0; $x = $x >> 8)
        $r = chr($x & 0xFF) . $r;
    return chr(strlen($r)) . $r;
}

function serialize_str($s) {
    return serialize_uint(strlen($s)) . $s;
}

function deserialize_uint($s, &$i = 0) {
    $e = $i + ord($s[$i++]);
    for ($r = 0; $i < $e; $i++)
        $r = ($r << 8) | ord($s[$i]);
    return $r;
}

function deserialize_str($s, &$i = 0) {
    $l = deserialize_uint($s, $i);
    $r = substr($s, $i, $l);
    $i += $l;
    return $r;
}