Justin Crooks wrote:
>
> > From: Scott Dattalo <sdattalo@UNIX.SRI.COM>

<snip>

> >
> >         MOVWF   temp            ;Hex value is in W.
> >         CLRC                    ;Clear the Carry bit so it doesn't
> >         RRF     temp,F
> >         CLRC
> >         RRF     temp,F
> >         CLRC
> >         RRF     temp,F          ;temp = h>>3
> >         ADDWF   temp,F          ;temp = h + (h>>3)
> What happens if result > 0xFF?

  The carry will get set and the next RRF will pick it up like a sponge
soaks up water.

> >         RRF     temp,F          ;temp = (h + (h>>3)) >> 1
> >         ADDWF   temp,F          ;temp = h + ((h + (h>>3)) >> 1)
> Again, same issue.

  Again, same answer.

> >         RRF     temp,F
> >         CLRC
> >         RRF     temp,W          ;d = W = (h + (h + (h>>3)) >> 1) >> 2
> >
> >         RETURN
>
> This is excellent, but will not work for values > 64%.  I like how clean it
> is, though.  You could add a line to check if MSB set.  Subtract 128 if
> set, and add 50% at the end.

The routine works just fine. Try it. The only limitation that it does
have is that it actually computes floor(x * 100 / 256). So if your
percentage is 88.7%, for example, you would get just 88%. For my
application this was okay.

Scott