If the most-significant bit of the one byte of this stream at the current cursor location is set, assign to the specified length the four-byte, two's complement integer (in host byte order) comprised of the four bytes of this stream at the current cursor location (in network byte order) with the most-significant bit unset; otherwise, assign to length the one-byte, two's complement integer comprised of the one byte of this stream at the current cursor location. Update the cursor location and return a reference to this stream. If this stream is initially invalid, this operation has no effect. If this function otherwise fails to extract a valid value, this stream is marked invalid and the value of length is undefined. Note that the value will be zero-extended.