> -----Original Message-----
> From: Scott Dattalo [SMTP:scott@DATTALO.COM]
> Sent: Tuesday, July 18, 2000 6:47 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [PIC]: Better way to rotate?
>
> set_bit:
>
>      movf   bitmask,w
>
>      iorwf  indf,f
>      btfsc  new_state,0
>       xorwf indf,f
>
>      clrc
>      rlf    bitmask,w
>      rlf    bitmask,f
>
>      btfsc  bitmask,0
>       incf  fsr,f
>
>
> 9 words/cycles in assembly, with the same caveats as the above routine
> (i.e. byteptr, which is fsr, and bitmask both need pre-initialization).
>
> Scott
>
Superb, I wish my brain worked that well.  I never seem to consider using
XOR, I have OR and AND far to firmly embedded into my boolean logic lobe :o)

Just one thing, I think the btfsc should really be a btfss (you wish to
perform the xor if new_state is zero).

This is one of those tricky functions that seems very hard to optimize in C.
Very timely thread though, I need to do something very similar in a project
I'm working on the moment.

Regards

Mike

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