Ricardo D. Medina wrote :

> I am trying my hand at relocatable code (using assembler for
> 16F628 and 16F877 parts), but I fell into a bit of a blind hole...
>
> The code is structured in three files:
> delay.o -> contains various delay subs, which are totally
> independent from the main program
> lcd.o     -> contains the LCD subs
> main.o   -> contains the main program flow, what I want to
> display, etc.

OK. so those are pre-assembled files then.
The problem here is that any assemply-time calculations
or ifdef's/endif's have already been "done", so you are more or
less stuck with whatever is in those .o files. This is *the*
reason why many don't use object libs with PIC development,
you loses all assembly time calculations and pre-processing.

Note, that using "libraries" of ASM files, isn't any
problem at all vis-a-vis relocatioble code...

>
> At first I statically set the port and bits to control the
> LCD inside lcd.o,
> but afterwards I decided that the whole point of using
> relocatable code is to be able to port it to other projects as
> easily as possible...

Yes, but keeping the "common" routines in ASM format, makes
things easier and more flexible.

> So, from
> then on, I used six variables in the lcd.o object file which would be
> defined in the main.o file. (the idea behind this is to be
> able to change the ports and bits used by the LCD, depending on the
> complexity or needs of the project.)
>
> So I defined:
> LCTRL -> The port which has the LCD control lines (RS, RW, EN)
> LBUS   -> The port which holds the LCD data/address
> LBUST -> LBUS direction control (LBUS's TRIS register)
> RS -> Bit n: for the RS line
> RW -> Bit n: for the RW line
> EN -> Bit n: for the EN line.
>
> The problem is that I can assign the registers in main.o, but
> not the bits!!

You can't assign anything in an .O file.
You do that in the ASM file, right ?

> For example:
> LPORTS  UDATA   0x05
> LCTRL    RES    1    ; Set LCTRL as PORTA
> LBUS    RES    1      ; Set LBUS as PORTB
>
> LTRIS    UDATA    0x86
> LBUST    RES    1    ; Set LBUST as TRISB

And that must be in an ASM file, not an .O file...

>
> and afterwards I set them global.... no problem there.... but I still
> haven't found a way to specify the three control bits in the
> main file, and getting them to be global!
>
> Can anyone give me a clue, or is the only way to do it to use
> a mask (like,
> if I want EN to be bit 2, I set a register as EN and I set
> it's 2nd bit, so
> if I want to  " bsf LCTRL,EN " instead I do:

If you use assembler symbols to keep your bit number
it works, and you save a GPR also.

> I'm very sorry to take up your time,

He he, you are not, if I don't let you :-) :-)

> If anyone can shed
> some light, I'd greatly appreciate it.

I think that if you look at it again, and think about having your
"library" routines as ASM files, you'll see that things will work
out a bit easier. You can take full advantage of the assembly
time calculations, symbols and pre-processing.

Jan-Erik.

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