Whoa!  Thanks for pointing that out...

*sigh* I guess that's another instruction...

movlw 0x01

and then use subwf.  Here is my current version...I made an optimization
at the end which saves two instructions (assuming the counter != 0,
since if it is zero we don't need to worry about timing), but in light
of the decf problem we're at 8 instructions not counting retfie...:

        movlw 0x01
        subwf T_FL0, f
        btfsc STATUS, 0 ;test carry flag
        subwf  T_FL1, f
        btfsc STATUS, 0
        subwf  T_FL2, f
        btfsc STATUS, 0
        decfsz T_FL3    ;requires that T_FL3 be one larger than normally
        retfie
        bcf INTCON, GIE

> -----Original Message-----
> From: adam-request@viratech.com [mailto:adam-request@viratech.com] On
> Behalf Of Andrew Warren
> Sent: Wednesday, August 07, 2002 2:42 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]: Four byte counter - best method?
>
> Barry Gershenfeld <PICLIST@mitvma.mit.edu> wrote:
>
> > If you otherwise have the time, how about figuring out
> > beforehand that you will reach zero on the *next*
> > interrupt, and leave yourself a flag for that.
> > Check at the top of the i.s.r. and you know
> > after a single test.
>
>     Before you even start to do things like that, though, it might
>     be helpful to re-read the data sheet and notice that DECF doesn't
>     affect the Carry flag.
>
>     -Andy
>
> === Andrew Warren -- aiw@cypress.com
> === Principal Design Engineer
> === Cypress Semiconductor Corporation
> ===
> === Opinions expressed above do not
> === necessarily represent those of
> === Cypress Semiconductor Corporation
>
> --
> http://www.piclist.com hint: The PICList is archived three different
> ways.  See http://www.piclist.com/#archives for details.

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.