Olin Lathrop <olin_piclist@EMBEDINC.COM> wrote:
> > Do you know such macroassembler that is able to recognize labels,
> > jump and call instructions to be able to keep a valid value in a
> > variable you suggested? Optimalisation is the most difficult job
> > when you try to write any compilator. To build a tree of a program
> > isn't trivial.
>
> MPASM certainly can't do that.  The scheme I talked about is not
> fully automatic.  I have the UNBANK macro which invalidates all bank
> assumptions.  It is usually used at labels where execution can come
> from more than one point.  At other places like subroutine entries
> and call points I already use macros that automatically do an UNBANK.
>
> > I would have been satisfied by a macroassembler that is able to do
> > nontrivial string operations with parameters sending to macro. Do
> > you know any?
>
> Microsoft MASM is the best assembler I've ever used, and it can do
> what you ask but is only for the Intel x86 processors.  Unfortunately
> MPASM is pretty stupid in its handling of macro arguments.

Assembly language is pretty simple to preprocess with Perl (or any
other scripting language, for that matter), and this allows you to
add fairly arbitrary macro-like capabilities.

For example, I wrote a preprocessor that implements flow control
commands (if/else/endif, loops, etc.) for the ADSP-21xx series of
DSPs. This pretty much eliminates having to manually create labels
within subroutines, avoiding the hassle of making up non-conflicting
names.

When I started working with PICs, I extended it to support them as
well. After fiddling around with Olin's DBANKIF/UNBANK macros, I
wrote a second preprocessor that inserts them automatically -- you
just need to "declare" the symbols that are in banked RAM and it
finds them wherever they're subsequently used. Together, these
make the source code much more readable and easier to work with.

Of course, this makes the toolchain rather complicated, involving my
two preprocessors, Olin's "prepic" processor, Olin's macros and then
the Microchip assembler and linker. I use Makefiles and the command-
line tools, so I really don't need to worry about it once it's set
up the first time.

-- Dave Tweed

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