Hi Tamas!

On Dec 29, 2007 11:02 AM, Tamas Rudnai <tamas.rudnai@gmail.com> wrote:
>
> Yes, that's ok, the only thing is that as I can see Dwayne's original code
> what he needs is:
>
> B[012] = A[012] + K[012]

I see now, you are correct.

>
> So up front of your solution the A is needed to copy to B which is 6
> additional instructions. That's 6+11 or if you combine the first add with
> the move then it'll be 5+10. In my interpretation the question is if there
> is a better solution than the claimed 14 cycles without the ADDWFC
> instruction.
>
> What I was thinking of is a 13 cycle version using rlf - could not test it
> as I'm on a holiday far away from my computer, so it could be wrong...
>

Well, I tried in my superopt and you can do it in one ins less, using:

; B[012] = A[012] + K[012] , K const.

        movf    A0,W
        addlw   K0
        movwf   B0

        clrf    B1,F
        rlf     B1,W
        addlw   K1
        addwf   A1,W
        iorwf   B1,F

        rlf     A2,W
        subwf   A2,W
        sublw   K2
        movwf   B2

You can do better if K0 == 0 or K1 == 254, 255, 0 or 1.

I also think that the middle segment is simpler than yours, and you can
modify it for C = A + B also.

    Daniel.
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