Re: Linking an ADA routine to a program written in C

[comar@dantes.enst.fr (Cyrille Comar)]

>>>>> "David" == David C Hoos, <david.c.hoos.sr@ada95.com> writes:
In article <01bba5e0$cf06b040$328371a5@dhoossr.iquest.com> "David C. Hoos, Sr." <david.c.hoos.sr@ada95.com> writes:

    David> This is an implementation-dependent thing.  Generally what
    David> has to be done is to tell the Ada compiler that the routine
    David> is to be called by a C compilation unit.  This is done with
    David> a pragma such a EXPORT or EXTERNAL, depending on the
    David> implementation.  Consult your compiler documentation,
    David> looking especially for discussions of Interface
    David> Programming.
    David> Further, the issue of "withed" packages pretty much
    David> requires that your main program be an Ada program.  If you
    David> already have a suitable "main" program written in C, you
    David> would need to put an Ada "wrapper" around the C main.  The
    David> C main might have to be renamed, depending on the Ada
    David> implementation, because some Ada systems use a routine
    David> called "main", which would confuse the linker of there were
    David> two "main" symbols declared.


Sorry to jump in a bit late on this thread but I just wanted to add
that all the above description is perfectly correct for Ada83 but is
far from the reality of Ada (Ada 95). Interfacing with most other
languages is not implementation-defined anymore. This is perfectly
well defined in the R.M. See description of pragma Import/Export and
definition of standard procedures adainit (for elaboration of the Ada
part when main is not in Ada) and adafinal (for finalization of the
same Ada part). All of this is completely standard and implemented as
required at least in GNAT but most probably in other Ada95 compilers
as well.

Cyrille