Hercules ECC Encoding

Victor,

This means that the ECC checksum bits are computed over an 82 bit vector.

The 82 bit vector consists of [Addr[21:3], Data[31:0]]

This is critical because not only does ECC this way detect bit flips, it also detects errors that
are on the address bus. If for example one of the address lines is stuck low, then it will cause
the wrong word to be read from Flash. Now if the ECC were only computed over the data bus
like the generic CPU from ARM does, then reading the wrong address from the flash might go
undetected because both the data and ECC over data could still be good; they would just be
from a wrong address in flash.

By adding the address to the ECC checksum equation - we've closed this gap.

-Anthony