Nicholas Kinar <[email protected]> wrote:

>Thanks, Steve!

No problemo.

>> Here is the simplest one for m=12:
>>
>> 0x05eb
>>
>> It is probably bit reversed from the OP's set-up,
>> The leading coefficient of one is deleted from
>> this constant.

>Yes, it appears that the Galois shift register requires bit reversed
>versions.

The way you're doing it, yes.

>> (Unlike the OP, I always put the LS term of the polynomial
>> in the lsb of a binary word, but after looking at OP's
>> code it seems more compact to do it his way.)

>Yeah, it's kind of an interesting way of doing things.

It's good to keep track of the algebra. For a generating
polynomial G of degree m over GF(2), you are computing the remainder

x^n mod G

for a series of values n=0, n=1,....

This remainder is a polynomial over GF(2) of (at most) degree m-1.
How you represent it in a bit field is totally up to you,
and your method is as correct as any.

Steve