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CRC (was Re: [f-cpu] F-CPU architecture...)


woodelf wrote:

Yann Guidon wrote:

and now, i'm back to my CRC algos :-)

See page 419 of Knuth (Vol 2) if you are using a simple CRC like say for a floppy disk. "polynomal aritmaitic is modulo b is identical to multiple-precison arithmetic with radix b except all the carries are suppresed. compare (1101)2 by (1011)2 binary with x^3+x^2+x+1 modulo 2: binary: .....1101 x...1011 -------- .....1101 ....1101 ..1101 -------- 10001111 polynominal modulo 2: .....1101 x...1011 -------- .....1101 ....1101 ..1101 -------- ..1111111 "

this can be found everywhere on the net
but "really fast algos" are not so common,
the best i have found being the one in info-zip (3,75 instructions/byte with x4 unrolling)
However, my application needs CRC16 so i can't simply copy-paste info-zip's source code.
but don't worry for me, i'm not too bad in asm programming.


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