Understanding the FCS_CTRL in Circuit Schematic

[ws0619]

http://vlsihomepage.com/wp-content/uploads/2007/10/crc_schematic.gif

Can someone explain to me what is the fcs_ctrl is?

I saw this circuit in this website(http://www.nigamanth.net/vlsi/ ).After I read it, I still don't understand how does the fcs_ctrl value comes from.

Anyone can explain it to me?

Thanks!

 

[berkeman]

There is an explanation of that control signal at the website you cite, but a couple links down:

http://nigamanth.net/vlsi/2007/10/12/cyclic-redundancy-check-crc/

.