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[I thought I sent this a long time ago, but today my email program claims I
never sent this. Let's send it again just to make sure.]

Dear ``Anbar System'',

Anbar System <anbarsystem@RIOPRETO.COM.BR> on 2001-05-21 01:54:12 PM
>I didn't understude very well yet.
>Could you give some detail of this fcall macro.
>
>for example:
>fcall    macro subroutine_name ;this will assume for all my fcall ?
>    local here                    ;....
>    lcall subroutine_name   ;....
>    pagesel here                ;....
>here:                               ;....
>     endm                        ;.....

It's pretty easy to use this macro.
First you just copy-and-paste it near the top of a ``.asm'' file (or put it in a
``.inc'' file and stick the appropriate ``include'' statement near the top of
that ``.asm'' file). You don't need to make any modifications. Then you use it
to call subroutines. Check out the example I've appended to this message. It
should compile and run.

>I didn't find "Help | MPLAB Assembler help,
>just "Help | MPLAB help.
>My corrent version is 5.11.00

Would you like to download
  MPLAB
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=AE Version 5.30
  http://www.microchip.com/10/tools/picmicro/devenv/mplabi/index.htm
?

Luis Fernando, AKA antoniasse <antoniasse@BRAILE.COM.BR> on 2001-05-22 =
09:53:18
AM asked:
...
>the fcall macro in my program
...
>works perfectly
...
>Have I set the PCLTAH bits back to the value of the
>"fcall" page on a return?

Yes.

OK, I'll try to explain what's going on here. If you really want to see=
 what the
linker does to your own code, I recommend looking at the ``.lst'' file =
generated
by the linker. (If you're an assembly language programmer, sometimes yo=
u learn
some clever tricks by looking at the code generated by optimizing C com=
pilers).

The macro preprocessor expands the
<pre>
     fcall sub4
     GOTO main
</pre>
into this:
<pre>
     pagesel sub4
     call sub4
     pagesel _4here
_4here:
     GOTO main
</pre>
. Then the compiler and linker expand that into 6 instructions. The exa=
ct 6
instructions are listed in the ".lst" file generated by the linker. (As=
 opposed
to the ".lst" file generated by the assembler). I've added my comments =
to that
".lst" file:

     ; ; first set the PCLATH bits in preparation for the call:
     ; pagesel sub4
000021   158a     BSF       0xa,0x3
                                                                       =
                 =20

000022   120a     BCF       0xa,0x4
                                                                       =
                 =20

     ; call sub4
000023   2006     CALL      0x6
                                                                       =
                     =20

     ; ; reset the PCLATH bits to "here", which is necessary for the lo=
cal GOTO.

     ; pagesel _4here
000024   118a     BCF       0xa,0x3
                                                                       =
                 =20

000025   120a     BCF       0xa,0x4
                                                                       =
                 =20

     ; ; do the GOTO
000026   2812     GOTO      0x12              GOTO main

I'm hoping that the ``pagesel'' logic in future versions of the compile=
r will
reduce this to 5 (maybe even 4 ?) instructions the next time I compile,=
 without
any changes in my source code.

--
David Cary


--------------------------------------------
; Originally by Luis Fernando;
; modified by David Cary.
;Here, a simple example

fcall     macro subroutine_name
     local here
     lcall subroutine_name
     pagesel here
here:
     endm

; normally I don't specify a particular address; the linker handles it
automatically.
mainloop  CODE 0x0012 ;PAGE0

main:
     fcall sub1
     fcall sub2 ; simple ``call'' would save a few bytes here.
     fcall sub3
     fcall sub4 ; if ``call'' or ``lcall'' were used here, this GOTO wo=
uldn't
work right.
     GOTO main

sub2:
     ; ...
     RETURN

sub3:
     ; ...
     RETURN

;-------------------------------------------------------------------
; normally I don't specify a particular address; the linker handles it
automatically.
a_few_subs         CODE 0x800 ;PAGE1

sub1:
     ; ...
     fcall sub2
     RETURN

sub4:
     ; ...
     fcall sub1 ; simple ``call'' would save a few bytes here.
     fcall sub3
     RETURN
; Luis Fernando

     END
; end main.asm





=

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