Hi,
We have been using the Altera Checksum block for offloading the TCP Checksum and all appears to function well in 99.9% of packets. However, it would appear that when the checksum should be 0xFEFF. It is always returned as 0xFFFF indicating the result before the final invert is 0.
I hacked the code on the Nios side to detect a zero case and automatically make it a 1 to reflect what appears to be the missing final fold if it has grown beyond a 16bit number. This fixed the issue, and as a result we changed the Verilog to match a different algorithm.
Have we used this block incorrectly and it was just luck it normally works or have we found a legitimate bug?
Cheers
Tim
