Re: Calling Ada from C

[Theodore Dennison <dennison@escmail.orl.mmc.com>]

Roger L Costello <costello@mbunix.mitre.org> writes:
>     I am trying (unsuccessfully) to call an Ada program from a C program.
> I am using the SUN (VADS) Ada, and SUN C.  I am running on a SUN SPARC 10.
..
> 
>     text_io.put_line ("Hello World");
..
> 
> I got the following errors:
> 
> Undefined                       first referenced
>  symbol                             in file
> STACK_LIMIT                         ./.objects/hello03
> _A_put_line.123S12.text_io          ./.objects/hello03
> ld: fatal: Symbol referencing errors. No output written to a.out
> 

All Ada compilers come with their own executive to perform stuff
like tasking, dynamic memory allocation/deallocation, and elaboration.
As a result, certain operations are not available when your "main" 
program is a C program, not an Ada program. I/O for SunAda appears to
be one of those things.Despite your protestations that "the Sun 
documentation hasn't been much help", Section 4.3 (Calling Ada From
Other Languages) in the Sun Ada programer's guide goes over this in 
great detail.

If you make your main program an Ada program, you can call C routines
with little trouble. These C routines in turn can call Ada routines 
with no trouble. This "wrapper" approach is specificly suggested by 
the SunAda manual (section 4.2). I have used this approach in the
past in real-world applications (gory details available upon request).

If you need any further info, just ask (I love this stuff).

T.E.D.