public function convertHexToDec($hex)
    {
        if (strlen($hex) < 5) {
            return hexdec($hex);
        }

        list($remain, $last) = array(substr($hex, 0, -1), substr($hex, -1));

        return bcadd(bcmul('16', $this->convertHexToDec($remain)), hexdec($last));
    }