protected function getInitialLength()
    {
        if (!isset($this->buffer[self::BYTE_INITIAL_LENGTH])) {
            throw new FrameException('Cannot yet tell expected length');
        }
        $a = (int)(ord($this->buffer[self::BYTE_INITIAL_LENGTH]) & self::BITFIELD_INITIAL_LENGTH);

        return (int)(ord($this->buffer[self::BYTE_INITIAL_LENGTH]) & self::BITFIELD_INITIAL_LENGTH);
    }