Roland wrote :

> Hi All
> 
> I'm moving an assembly program from a 16F877 to a 18F452
> 
> Still editing the syntax at the moment, and wondered if I'm 
> on the right track. I'm simply building and editing until all
> the errors go away.

Might be OK, if you just need a "working" prog.
It will probably not be "18-optimized" though...

> 
> Basically;
> - I'll need to attend to some new SFR's, and some name changes

Obviously, yes... :-)

> - Interrupts can be split to high and low priority

But just becuse you can, do you need that ? From what I
have understod, most just use the single level interrupt system.

> - I intend to use Bank1 of ram, so;

Why ? Are you not using (the lower half of) bank0 at all ?
If so, you miss the whole "access bank" thing. That is one
of the realy nice things with the 18-line.

>   - my Cblock starts at 0x100

I bet *someone* will add that you *should* look at RES and
use the linker instead... :-) You don't have to do that, but I would...

>   - all my old FSR and INDF become FSR1 and INDF1
> - many of the 'goto's become 'bra' (within branch limits)
> 
> What I'm unsure of is:
> - in the old code I had; goto $ + 5

Do yourself a big favour and throw them out at once !
Add lables and goto (or branch) to them instead. If you
had done that in your PIC16 code in the first place, that
had been portable as-is.

> - in the new code do I have to use; bra  $ + 5 
> but I still get: "Warning 226: Destination address must be 
> word aligned"

Correct. As expected. Since each instruction is on an even
address, and you are adding an odd value, you will end up
on an odd address, right ?   "even" + "odd" = "odd"...

> what do I do to alleviate this? The manual say's
> 
> "
> 226 UNKNOWN WARNING
> A warning has occurred which the assembler cannot understand. 
> It is not any
> of the warnings described in this appendix. Contact your 
> Microchip Field
> Application Engineer (FAE) if you cannot debug this warning.
> "

Don't bother. Just get those goto/bra $-something out and
add lables instead.

> Any other common snags to watch for?

The rotate instructions, if I'm not wrong.
I think there are som changes how the carry bit is handled
in some arithmetic instruction, but I'm not sure...

Jan-Erik.



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