Looking for an efficient CRC
Ashley Roll email (remove spam text)
> Is there a good CRC or error detection mechanism that can be
> consume only
> few instructions for each byte of data ? Somebody mention to
> us that we can
> speed up algorithms such as CRC16 using lookup tables but I
> don't think the
> 12c508 can hold tables of decent size.
I was probably the one you were thinking of. I suggested that one could
implement a table based CRC16 using tables less then 256 items in a
discussion about a week ago.
For instance you could build a CRC16 that updates 4 bits per time using two
16 element tables. This is 32 instructions for data plus a few extra
instructions to do the jump into the table. This should easily fit on the
first code page in a 12C805 if you haven't got any other tables you should
I've not actually tried to implement this technique yet, but it should work.
From a quick "Guess-timate" of the algorithm it will probably be somewhere
in the order of 50-70 instruction cycles per byte to update the CRC..
Is that going to be fast enough?
Maybe its time I actually tried to implement this..
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