From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,
	T_FILL_THIS_FORM_SHORT autolearn=ham autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII
X-Google-Thread: 103376,8141f2ef049fcd7e
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2001-10-11 06:39:29 PST
Path: 
 archiver1.google.com!news1.google.com!sn-xit-02!supernews.com!newsfeed.direct.ca!look.ca!hammer.uoregon.edu!skates!not-for-mail
From: Stephen Leake <stephen.a.leake.1@gsfc.nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: Help with GNAT, WinNT, StdCall, dll, exported names
Date: 11 Oct 2001 09:28:22 -0400
Organization: NASA Goddard Space Flight Center
Message-ID: <un12ye26h.fsf@gsfc.nasa.gov>
References: <%lfx7.6$_o6.503@newsc.telia.net>
NNTP-Posting-Host: anarres.gsfc.nasa.gov
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: skates.gsfc.nasa.gov 1002807013 24072 128.183.220.71 (11 Oct 2001
 13:30:13 GMT)
X-Complaints-To: dscoggin@cne-odin.gsfc.nasa.gov
NNTP-Posting-Date: 11 Oct 2001 13:30:13 GMT
User-Agent: Gnus/5.0808 (Gnus v5.8.8) Emacs/20.7
Xref: archiver1.google.com comp.lang.ada:14256
Date: 2001-10-11T13:30:13+00:00
List-Id: <comp.lang.ada>

"Peter Hend�n" <phenden@tdab.com> writes:

> I'm using gnat 3.13p, trying to build a dll that exports functions
> that are to be called by a windows service. The problem is
> that the functions are declared in the .h file as
> 
> BOOL WINAPI Foobar(LPFUNNY_STRUCT fum);
> 
> Now I have defined an Ada function for this, and
> it works fine when I export it as
> pragma Export(C, Foobar, "Foobar");.
> 
> Of course this will be called exactly once, because
> it is the wrong calling convention, and after its return
> the stack is fubar.
> 
> When I try to declare it StdCall instead of C, I am
> not able to link it. Whatever I put in the .DEF file
> it comes out wrong. I get from the last gnatlink step
> in gnatdll:
> 
> mydll.exp(.edata+0x34):fake: undefined reference to `Foobar'
> 
> I have tried everything in the gnat user's guide, searched
> this groups archive and generally banged my head against
> the wall in appropriate - and perhaps not so appropriate -
> ways. Please help!

You don't mention what C compiler you are using. I have found that
different C compilers (and different Ada compilers) have different
naming conventions, usually having to do with prepending and
underscore. Here's my matrix:

compiler    calling     function    link    DLL
            convention  name        name    name

Borland C++ Cdecl       foo         _foo    _foo
            stdcall     foo         foo     foo

Borland C   Cdecl       foo         _foo    _foo
            stdcall     foo         foo     foo

GNAT Ada    C           foo         _foo    foo
            (stdcall not supported in DLLs)

Gnu C       C           foo         _foo    foo

ObjectAda
Ada         DLL_Cdecl   foo         _foo    foo
            DLL_Stdcall foo         _foo    foo


I also have this note:

Since GNAT Ada does not support the stdcall convention for DLLs, we
use the Cdecl convention everywhere. 

That was true for 3.12, apparently it's not true anymore.

Hope this helps!

-- 
-- Stephe