MessagePack\BufferUnpacker::unpackUint64 PHP Method

    private function unpackUint64()
    {
        if (!isset($this->buffer[$this->offset + 7])) {
            throw new InsufficientDataException(8, \strlen($this->buffer) - $this->offset);
        }
        $num = \substr($this->buffer, $this->offset, 8);
        $this->offset += 8;
        //$num = \unpack('J', $num);
        $set = \unpack('N2', $num);
        $value = $set[1] << 32 | $set[2];
        // PHP does not support unsigned integers.
        // If a number is bigger than 2^63, it will be interpreted as a float.
        // @link http://php.net/manual/en/language.types.integer.php#language.types.integer.overflow
        return $value < 0 ? $this->handleIntOverflow($value) : $value;
    }