private function encodeNumber($num)
    {
        $encodeString = '';

        while ($num >= 0x20) {
            $nextValue = (0x20 | ($num & 0x1f)) + 63;
            $encodeString .= chr($nextValue);
            $num >>= 5;
        }
        $finalValue = $num + 63;
        $encodeString .= chr($finalValue);
        return $encodeString;
    }