Using GNAT in a C and assembly toolchain

[Tom <tomahawkins@gmail.com>]

On May 3, 12:03 pm, Simon Wright <si...@pushface.org> wrote:
> I think your problem may be that your host compiler is an older version
> (4.4.3) than the source tree you're using to build the cross compiler
> (4.5.0). The recommendation is to build the host compiler first, then
> use that to build the cross.
>
> The symbols you're missing are (in 4.5.0 but not in 4.3.4, the only
> handy version I have for comparison) defined in adaint.c, and it looks
> as though adaint.o is being picked up from the pre-built host libraries
> (not surprising, the cross-compiler has to run on the host so needs to
> use host file attributes etc).

Thanks Simon.  That did the trick.  I now have a functioning Ada cross
compiler; I just need to learn how to use it.  I could use a few
pointers to get me started...

On our particular application -- an automotive ECU -- we're locked
into a proprietary C-based flow.  The operating system and hardware
abstraction layer come precompiled and the application code must be
compiled and linked with the established tool chain (GHS C, not Ada).
The application programmer defines a procedure, which is invoked by
the OS as a periodic rate.  This procedure references global C
variables to access the hardware abstraction layer.

The question is how can I best use Ada and GNAT in such an
environment?  One method that comes to mind is to compile Ada to
assembly code, which is then passed to GHS for assembling and linking
with the closed source OS and HAL.  I don't see an assembly switch,
like GCC's -S.  Would this mean I would need the compile Ada modules
individually with GCC instead of using gnatmake?  Are there any
options to compile Ada down to C by chance?

And how does gnatbind fit into this picture?  It appears to create
initialization code.  Would I just need to insert this code such that
it is invoked at power up?

-Tom