Re: Is it possible to build an Ada cross-compiler for an 8-bit embedded target now that gcc 3.X has support for Ada?

["Randy Brukardt" <randy@rrsoftware.com>]

"Peter Milliken" <peterm@resmed.com.au> wrote in message
news:zgRsb.200$co2.10332@nnrp1.ozemail.com.au...
> Subject pretty much says it all.
>
> Now that you can build an Ada compiler using gcc 3.X (well, according to
the
> build instructions of gcc 3.x :-)), I began to wonder whether it was
> possible to build a cross-compiler for an 8-bit target processor. The
8-bit
> processor family in question is already supported by gcc (I believe).
>
> When I say "possible", I just mean "follow the cross-compiling
instructions
> and out pops an Ada compiler" - I don't mean, "spend months of work
patching
> various files and then you might have an Ada compiler" :-)

To not answer your actual question at all, but...

As someone else pointed out, the biggest cost/overhead is porting the
runtime libraries. Speaking for Janus/Ada, porting the code
generator/compiler usually only takes a month or so (and that's for building
a code generator from scratch). But building the basic runtime support for
exceptions, tasking, floating point (which usually has to be emulated on
small processors), etc. can take a lot of time. In addition, that support
can make programs quite large.

Because of this, I think you'd have trouble making acceptable programs with
a general-purpose compiler like GCC.

Janus/Ada was originally built for Z-80 and 8086 processors without much
memory. Thus, we only load floating point and tasking support when they are
used. That isn't very valuable on standard systems like Windows these days,
but it matters a lot on 8-bit systems.

The only reason that we don't support 8-bit processors is a lack of demand.
Everyone seems to use a different processor, and thus we cannot really
justify the investment building code generators (easy) and runtime libraries
(not as easy) for each one.

Of course, we're always interested in customization projects, but that won't
help you convince your manager...

                   Randy Brukardt