"Ignacio G.T." <(E-Mail Removed)> wrote in message

news:(E-Mail Removed)...

> Dear all:

>

> I have to compute a long CRC (85 bits).
I am curuous what is this for?

> I'm used to compute 16-bits and

> 32-bits CRCs, using tables or using "brute-force" algorithms (via

> software) which make use of the fact that 16 bits or 32 bits makes a

> word or half a word.

>

> But 85 bits demands, perhpas, other approaches, to be effective.

> I wonder if some of you can point me in the right direction. Is there

> any other group more suited to be asked? Books, references?
CRC is a remainder of the polynomial division. Thus you can extend the 85

bit CRC polynomial to 96 bit polynomial, which is a multiple of machine

word. The 96 bit CRC can be computed efficiently, and then you convert the

96 bit CRC to 85 bits.

Vladimir Vassilevsky

DSP and Mixed Signal Consultant

www.abvolt.com