question: private void updateCrc ( Buffer buffer , long offset , long byteCount ) { Segment s = buffer . head ; for ( ; offset >= ( s . limit - s . pos ) ; s = s . next ) { offset -= ( s . limit - s . pos ) ; } for ( ; byteCount > 0 ; s = s . next ) { int pos = ( int ) ( s . pos + offset ) ; int toUpdate = ( int ) Math . min ( s . limit - pos , byteCount ) ; crc . update ( s . data , pos , toUpdate ) ; byteCount -= toUpdate ; offset = 0 ; } }
target:  Updates the CRC with the given bytes. 