looking for sample code for 16/32bit CRC

I know there are samples of code that deal with the topic I am asking for but, I am looking for one that will handle stream of bytes (networking CRC's) for C++ project. I will use the 32bit CRC on stream data and then add the UDP information with a 16 bit checksum.

Wikipedia has a pretty good article on cyclic redundancy checks. It also references some algorithms here.

thanks