[usb] preloading CRC

[Rudolf Usselmann <rudi@asics.ws>]

Just a comment about pre-loading the CRC generators ...

Most standards USB, Ethernet, etc. specify the default pre-load
value. Typically this value is all '1'. This is a mandatory operation
for the transmitting station.

On the receiving station, I prefer to pre-load the CRC *checker*
with the polynomial. The final result from the CRC checking
should be the original pre-load value of the Transmitting station.

The reason I like to do this, is because it takes less logic to just
check if all bits are '1': Simple AND gate.

But of course there are many other ways to do this ...

Cheers,
rudi


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