Optimizing CRC16 routine.

[cncmachineguy]

Not saying I get this whole CRC thing, just looking at the 2 snippits, the biggest thing I see is you have a nested loop and Darrel doesn't. But that seems like it would change things by more than double. (approx difference between the 2)

Try using his poly instead of yours in your code to see if that changes your timing. I don't know if you can just do that, but if so it will eliminate that as a factor.

[HenrikOlsson]

Hi Bert,
I tested with $1021 instead of $A001 as the poly and it changed from 1730 to 1682 cycles - still nowhere nere ~800.

Yes, mine iterates thru the array of 9 bytes (in this case) in one go while Darrels would have to be called 9 times with a new byte in CRC_In each time. I don't think that is what makes it that much slower.

I'm new to this CRC thing as well and don't yet fully understand it enough to try to come with a completely different aproach.

Thanks!
/Henrik.