Am I nuts here or does that fifth instruction need to be decfsz (bbb), w?
Yours Truly, Keith Causey

-----Original Message-----
From: Bob Fehrenbach <bfehrenb@EXECPC.COM>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Monday, December 28, 1998 9:41 AM
Subject: Re: 16-bit subtraction routine


>Keith,
>
>Try this,
>
>;*******************************************************************
>;  Two byte subtract.
>;  At exit, if C = 1, result is positive.
>;  Usage example:   sub_word new_count, old_count
>;  Note: Zero flag NOT valid at exit
>;*******************************************************************
>
>sub_word: macro aaa, bbb
>   movf    (bbb+1), w
>   subwf   (aaa+1), f
>   movf    (bbb), w
>   skpc
>   incfsz  (bbb), w
>   subwf   (aaa), f
>   endm
>
>
>
>Keith Burzinski wrote:
>>
>> Hello fello PIC-Listers...
>>
>> Has anyone got a good, fast routine to subtract two 16-bit numbers
>> that they'd be willing to share?  I figured I'd ask out here
>> first... why re-invent the wheel?  ;)
>>
>> Cheers,
>> --
>> ~Keith
>> tsk3000@Prodigy.Net
>> ICQ UIN 15590177
>> http://pages.prodigy.net/tsk3000/
>