Dmitry and Scott, Thanks. Both routines work on the other way. Thinking
"binary" is not so hard with these kinds of examples. They justify pics.
Now we have a rotating-1-bit-set routine in a high nibble, both ways, with
out an auxiliary register

Dennis.

Ps: Also to Olin

Sent: Sunday, October 05, 2003 6:45 PM
Subject: Re: [PIC:]Rotate a 1 in high nibble


> > How about shifting the other way?
> >
> >      rrf    reg,W           ;start the rotate
> >      andlw  b'01110000'     ;only wan't the upper nibble
> >      btfsc  reg,4           ;copy the lsb of the upper nibble
> >       iorlw b'10000000'     ;to the msb
> >      xorwf  reg,W           ;write the nibble back by getting
> >      andlw  b'11110000'     ;the difference.
> >      xorwf  reg,F           ;  new = (old^new) ^ old
> >
> > Scott
>
>
> Untested.
>
> movfw   reg             ;? abcdefgh
> andlw   0x0F            ;? ....efgh
> btfsc   reg,4           ;?    d?
> iorlw   0xF0            ;? ddddefgh
> addwf   reg,F           ;d abcefgh0
> rrf     reg,F           ;0 dabcefgh
>
>
> WBR Dmitry.

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