Bob Ammerman wrote:
>
> Yes: xorlw method is a bit smaller.
>
> Yes: this method requires at least one word in low half of page.
>
> But: this method is significantly faster.
>
> So: horses for courses.


Yep it's a bit quicker, but a lot messier.
The XORLW system you posted is as neat as
a normal table, and can have more units added
to it at any point or subtracted from it.

Also with a larger table size it would get
significantly smaller (and be MUCH neater).

All in all I thought your XORLW system was
totally brilliant, only takes 2 words per
table byte and is very neat and simple.
Unless speed is the main issue I think it
would be horse chosen for my course. ;o)
-Roman


> > > Bob Ammerman wrote:
> > > >
> > > > I knew it, I knew it...
> > > >
> > > > There _is_ a two instruction per entry technique!
> > > >
> > > >     movlw     value1^value2^value3
> > > >     decfsz    count,F
> > > >     xorlw       value1
> > > >     decfsz    count,F
> > > >     xorlw       value2
> > > >     decfsz    count,F
> > > >     xorlw       value3
> > > >     etc.
> > > >
> > > > Notice what happens:
> > > >
> > > > If count == 1 on entry then all the xor's except value1 occur,
> > > > leaving 'value1' in W.
> > > >
> > > > If count == 2 on entry then all the xor's except value2 occur,
> > > > leaving 'value2' in W.
> > > >
> > > > If count == 3 on entry then all the xor's except value3 occur,
> > > > leaving 'value3' in W.

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