Bob Blick <bblick@TELIS.ORG> wrote:

>>        movf    Source,w
>>        btfsc   C
>>         incfsz Source,w
>>         addwf  Dest,f

>Please continue with the explanation of this one, I'm not quick enough to
>figure out what you're doing.

Bob,

Perhaps a whole macro would illustrate:

   ;Two byte add.   Standard PIC instruction set does not have an add
   ;with carry instruction.
   ;At exit, if C = 1, result is greater than 2 bytes.
   ;Usage example:  add_word buff, new_data

add_word: macro aaa, bbb
   movf    (bbb+1), w
   addwf   (aaa+1), f
   movf    (bbb), w
   skpnc
   incfsz  (bbb), w
   addwf   (aaa), f
   endm

Bob



--
Bob Fehrenbach    Wauwatosa, WI     bfehrenb@execpc.com