Re: Interfacing Ada Routines in C

[Andy McNerney <andy.mcnerney@gecm.com>]

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    |
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