Olin Lathrop wrote:
>
> I didn't look at your code, but my immediate knee jerk reaction is that
> keeping AM/PM flags around is a bad design choice.  Use 24 hour time
> internally.  Whether you then display 24 hour or 12 hour time with
> AM/PM is
> only a matter of the display logic.

Given that a deliberate design choice was that this clock will only ever
display 12-hour time, I don't see that there's an overall advantage in
storing the time in 24-hour format. Yes, it would simplify my "add 1 minute"
routine, taking the AM/PM logic out of that routine - but all that does is
move some fairly equivalent logic into the display routine.  There's not
much in that trade-off, but keeping the internal time format closely matched
to the display format (to me) makes the code clearer overall.

> > So finally to the point.  Does anyone know an elegant way to compare
> > (XOR) two bits in the same register, using midrange PIC instructions?
> 
> Why does it need to be elegant?  The extra cycles are irrelevant.

That's true (to a point of course).

> Write it to make the most sense when someone reads the code.

Yes - I hoped that someone had an idea that was actually easier to follow
than a set of four bit tests.

>  This includes giving symbolic names to the bits.

Had you looked at my code you would have seen that I had done that...


David Meiklejohn
www.gooligum.com.au





-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist