On Mon, 23 Oct 2000 rich+piclist@LCLOGIC.COM wrote:

> 5 cycles:
>
>         comf indf,w
>         addlw 1
>         andf indf,w
>         subf indf,w
>         return
>
> The good old x&=-x trick! == Rich

Nope! Close, but it doesn't quite work. (0 is not a power of 2)

If you weren't worried about 0, then this would be 33% faster:

    decf  indf,w
    andwf indf,w
    return



Scott

>
> On Mon, 23 Oct 2000, Scott Dattalo wrote:
>
> > Date: Mon, 23 Oct 2000 22:04:20 -0500
> > From: Scott Dattalo <scott@DATTALO.COM>
> > Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: [pic]: Challenge: power of two test
> >
> > Write a function that returns zero if INDF is a power of two, else returns
> > non-zero.

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