1. Apparatus for generating C-bit payload check data from K-bits of payload data formed of N M-bit words, where K=N*M and N and M are integers greater than one, said apparatus comprising: N lane encoders configured to operate in parallel to each generate lane check data from a respective M-bit word using a common processing operation; and mask circuitry coupled to said N lane encoders and configured to receive lane check data from each of said N lane encoders and to generate said C-bit payload check data.