Ron Kreymborg <PICLIST@MITVMA.MIT.EDU> wrote:

> If the numbers are unsigned, and stored msb at the lower address,
> you could try
>
>         movf    new+1,w         ; subtract lsbs
>         subwf   old+1,w
>         movf    new,w           ; subtract msbs
>         btfss   status,c        ; including any carry
>         addlw   1
>         subwf   old,w
>         btfsc   status,c        ; new smaller?
>         goto    smaller         ; yes
>         goto    larger          ; no

Ron:

I think you meant for that "BTFSC STATUS,C" to be a "BTFSS".

Also, your code works for Marcel's application (12-bit subtraction),
but it fails on 16-bit numbers when "new" is greater than 0xFF00.

A routine that works for all 16-bit numbers is:

        MOVF    NEWLO,W
        SUBWF   OLDLO,W
        MOVF    NEWHI,W
        SKPC
        INCFSZ  NEWHI,W
        SUBWF   OLDHI,W
        BC      NEW_IS_LARGER_OR_EQUAL
        GOTO    NEW_IS_SMALLER

-Andy

=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - Vista, California
=== http://www.geocities.com/SiliconValley/2499