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=0.2 required=5.0 tests=BAYES_00,INVALID_MSGID,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,ef3ff2cf59eff560
X-Google-Attributes: gid103376,public
From: Ara Kassabian <akass@worldnet.att.net>
Subject: Re: Help with Gnat Cross-compile
Date: 1998/04/16
Message-ID: <6h57uk$d2s@bgtnsc02.worldnet.att.net>#1/1
X-Deja-AN: 344687646
Content-Transfer-Encoding: 7bit
References: <6gtil3$jdi$1@hirame.wwa.com>
Content-Type: text/plain; charset=us-ascii
Organization: AT&T WorldNet Services
Mime-Version: 1.0
Reply-To: akass@worldnet.att.net
Newsgroups: comp.lang.ada
Date: 1998-04-16T00:00:00+00:00
List-Id: <comp.lang.ada>


Samuel G. Williams wrote:
> 
> I am looking for good examples on two scenarios. The first is the compile of
> Ada code for later linking in C. I would also like any recommendations for call
> converntions. Second I am looking for the reverse. Being able to compile c
> then link in with Ada also with the calling conventions. I am currently
> attempting to help a friend without an Internet connection obtain this
> information. I would welcome all replies. BTW he is using GNAT on a Solaris
> workstation. He found brief entries in the GNAT UG but didn't quite
> understand them well enough to be useful.
> 
> Thanks in advance for your help.
> 

In Ada-83, interfacing with C was as easy as using the right pragmas, so long as
you didn't run into threading issues (both the C and Ada-83 parts of our program
were threaded, and the two threading packages were not aware of each other). It
*should* be just as easy with GNAT. The procedure should be:

1. Calling C from Ada: Write a package spec declaring the C functions and using
"pragma import", so Ada knows it needs to use C calling conventions.

2. Calling Ada95 from C: Write a header file with the Ada95 function/procedure
prototypes. If you cannot turn off name mangling in Ada95 using a pragma, then
you need to compile your files, figure out the mangled names by looking in the
object files and use those as your function names in your C header files. You
make things look pretty by using #define to create unmangled aliases for the
mangled functions. You *may* run into problems with Ada95 procedures. I am not
sure if they equate to void functions in C.

------------------------------------------------------
Ara Kassabian            akass@worldnet.att.net
                         akassabian@logicon.com (work)
------------------------------------------------------