Re: Calling Custom C Functions From Ada

["Warren W. Gay VE3WWG" <ve3wwg@home.com>]

Brant wrote:
> I'm trying to call a custom C function from an Ada program.  I've set
> my Ada program up using the INTERFACE pragma, but I can't seem to get
> the linker to locate the associated C object code.
> 
> I've written and built my C functions using Microsoft Visual C++; I've
> tried both static and dynamic libraries, so I get the *.lib, *.obj
> files along with a *.exp file.  I'm using a DDC-I DACS Ada compiler
> under Windows NT.
> 
> When I link my Ada code, which one of the generated C files do I need
> to reference?  No matter which I choose I get an "adalink: undefined
> reference to `MyFunction'" error, which is the same error I get when I
> don't even point to a file.  Do I need to do some tweaking of the C
> files?  Do I need to reference the specific function (as opposed to
> just a file) when I link?

If you've not already done so, make sure you compile your C function
with extern "C" linkage. Otherwise the function name get's mangled 
according to C++ mangling conventions:

extern "C" int my_function(void);

or :

extern "C" {

   int my_function(void);

}

-- 
Warren W. Gay VE3WWG
http://members.home.net/ve3wwg