Geoff Wootton <PICLIST@MITVMA.MIT.EDU> wrote:

> Does anyone know where I might be able to download some basic
> multi-byte arithmetic routines. For example, code for 16 bit
> subtraction etc.

Geoff:

You can (usually, except when the site's under construction) get
code like this from my web page.  Here's a 16-bit subtract for the
16Cxx:

        ;
        ; A = A - B.  Enter with A in "AHI:ALO", B in "BHI:BLO".
        ;             Exits with difference in AHI:ALO.
        ;

        MOVF    BLO,W
        SUBWF   ALO
        MOVF    BHI,W
        SKPC
        ADDLW   1
        SUBWF   AHI

Off the top of my head, it looks as though code for the 16C5x would
be identical, except that you'd want to replace the "ADDLW 1" with
"DECF AHI".

-Andy

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