Thomas,

First, as Olin would say: you are not owed an answer here. However, since
I'm a much nicer guy than he is ;-) I'll try to help you:

The 'pagesel' works to restore the page because it can just jam the
appropriate code address bits into PCLATH.

On the other hand, to restore the bank, you'd have to save it someplace
first. You can't just store STATUS in some handy place and restore it later
for a couple reasons:
    1: You'd be tweaking more than the bank bits.
    2: If the routine you called ended up using GCALL itself it would
overwrite the save area on you.

One possibility would be to push the bank bits onto a software stack and
restore them afterword. We can store a four level stack in a single byte (2
bits per level). Lets call the variable we use for this purpose "GSTACK".
You will need to ensure that this location is visible in all banks. This
would be in locations 0x70 thru 0x7F on the PIC16F62x and PIC16F87x chips.

So, your GCALL could end up looking like this:


    rlf    GSTACK,F            ; make room for two more bits
    rlf    GSTACK,F
    bcf  GSTACK,0
    bcf  GSTACK,1
    btfsc  STATUS,RP0
    bsf    GSTACK,0
    btfsc  STATUS,RP1
    bsf     GSTACK,1

    lcall     name
    pagesel    here

    bcf     STATUS,RP0
    bcf     STATUS,RP1
    btfsc   GSTACK,0
    bsf      STATUS,RP0
    btfsc    GSTACK,1
    bsf      STATUS,RP1

    rrf        GSTACK,F    ; pop old bits off
    rrf        GSTACK,F


rather a lot of code, don't you think?

It would probably be better to just explicity set the correct bank upon
return from the routine.

Bob Ammerman
RAm Systems





> >;----------------------------------------------------------------
> >GCALL   MACRO name
> >        local here
> >        lcall name
> >        pagesel here
> >here
> >        ENDM
> >
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