Interfacing Ada Routines in C

Interfacing Ada Routines in C

[Steven To]

  Does anyone know how I can interface an Ada procedure in my
C program? 

  I've tried the following unsuccessfully:
  
  Compiled the ada procedure into an object file. Included
the ada object file during the link, but the compiler isn't
able to find the procedure referenced in my C program.

  BTW, I am using gcc and Sun Ada on a Solaris platform.


-- 

                                     Steven P. To
                                     sto@cs.ucr.edu
                                     http://www.cs.ucr.edu/~sto

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-- 

                                     Steven P. To
                                     sto@cs.ucr.edu
                                     http://www.cs.ucr.edu/~sto

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Re: Interfacing Ada Routines in C

[Greg Baker]

sto@cs.ucr.edu (Steven To) writes:
>   Does anyone know how I can interface an Ada procedure in my
> C program? 
> 
>   I've tried the following unsuccessfully:
>   
>   Compiled the ada procedure into an object file. Included
> the ada object file during the link, but the compiler isn't
> able to find the procedure referenced in my C program.
> 
>   BTW, I am using gcc and Sun Ada on a Solaris platform.

The Ada compiler does some slight name mangling (it includes the name
of the package in the link name). 
Without checking too carefully..

Ada:
 package Foo is
   procedure Bar;
 end Foo;

C:
  extern void foo__bar();
  
I derived the above information by compiling the foo package, and
running "nm foo.o | grep bar".  (Actually I did nothing of the sort,
I'm just going from memory).

Hope this helps.

-- 
Gregory D. Baker        gbaker@rp.csiro.au         CSIRO Radiophysics 
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I am about to leave CSIRO. The above email address and URL may become
                    invalid in October.

Re: Interfacing Ada Routines in C

[Andy McNerney]

Greg Baker <gbaker@walleroo.rp.csiro.au> wrote:

>>   Does anyone know how I can interface an Ada procedure in my
>> C program? 
>>   I've tried the following unsuccessfully:
>>   
>>   Compiled the ada procedure into an object file. Included
>> the ada object file during the link, but the compiler isn't
>> able to find the procedure referenced in my C program.
>> 
>>   BTW, I am using gcc and Sun Ada on a Solaris platform.
>
>The Ada compiler does some slight name mangling (it includes the name
>of the package in the link name). 
>Without checking too carefully..
>
>Ada:
> package Foo is
>   procedure Bar;
> end Foo;
>
>C:
>  extern void foo__bar();
>  

This, unfortunately, is an Appendix F issue.  The way I have had to do it, using 
gcc and gnat ADA, on an SGI is to use PRAGMA EXPORT within the ADA, so that the
C can see the symbol with the name of your choosing : Eg:


function create (bob : in bob_type) return integer;
PRAGMA EXPORT (c, create, External_Name => "create");

--------------------------------------------^^^^
This can be what ever you wish to call the routine as seen from the C.


Using VERDIX ada, also on SGI the synax is as follows:

function create (bob : in bob_type ) return integer;
PRAGMA external_name ( create, "create");


This aviods you 'hacking' the C to get it to work.

Hope this helps.

-------------------------------------------------------------------------
   Andrew A McNerney                   | 
   andy.mcnerney@gecm.com              | These are my personal opinions
   GEC Marconi S3i                     |  and NOT those of my employer.
   Simulation and Training Division    |
-------------------------------------------------------------------------

Re: Interfacing Ada Routines in C

[Robert Dewar]

Steven asks

"  Compiled the ada procedure into an object file. Included
the ada object file during the link, but the compiler isn't
able to find the procedure referenced in my C program."

You should read two things. First the documentation in gnatinfo.txt on
running when the main program is not Ada, if this applies.

Second the description of pragma Export. Your gave only sketchy details
but perhaps you are missing an external name argument on your Export
pragma.