Dmitry A. Kiryashov wrote:
>Actually Bob answer is too prefect to improve it ;)

It=B4s so nice I=B4m putting it in my 16bit macro file. :)
And... the carry out IS correct, right?

I found a 16bit subtract constant in my archive which I append at end.
I=B4m too tired to convince myself about the carry on that one for the=
 moment though.

I tend to believe there is also a five cycle add constant solution.
Five cycle subtract register from register seem impossible... not?

Gotta go
/Morgan

>Bob Ammerman wrote:
>
>> Challenge
>>
>> If you don't care about the carry out, it's possible to perform a 16-bit=
 add in
>> 5 cycles. Since Nikolai is away from his computer, Dmitry is quiet, John=
 is
>> (where is John?) and Andy is on a plane, this oughta be an interesting
>> challenge.
>>
>> Scott
>
>   movf      lo_a,W
>   addwf    lo_b,F
>   rlf           known_zero,W
>   addwf    hi_a,W
>   addwf    hi_b,F
>
>Bob Ammerman
>RAm Systems
>
>> (contract development of high performance, high function, low-level
>> software)
>
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------------------------

Part of mail on PICLIST from Rich Leggitt <rleggitt@concentric.net>=
 2000-03-11 :

Consider subtraction of 16-bit constant from memory:

PIC =3D 5 cycles/70 bits (14 bit core):

        movlw low(const)
        subwf LO,f
        rlf ZERO,w
        sublw high(const)+1
        subwf HI,f


Regards
/Morgan

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