Re: [open-cobol-list] OpenCobol (Windows) and DB2

[Frank Swarbrick]

Franklin Ankum wrote:

> Hi Frank,
>
>
> > Has anyone attempted, or better yet had success, with compiling any of
> > the DB2 LUW v8.2 samples using Sergey's OpenCOBOL Windows binaries?
> > From what I can tell the DB2 API functions must be called using the
> > __stdcall calling convention, while OpenCOBOL is built using the __cdecl
> > calling convention.  Is there any way I can force the sqlapi calls to
> > use __stdcall while keeping all of the others as __cdecl?
>
>
>
> Yes, i also had this problem!
> I did i dirty trick to make these calls work:
> By changing every call to "sqlg????" in the DB2 Precompiled output to 
> "sqla????"
> These are the API Calls for C-Programs.


> I did many test and everything seems to work fine, although i'm not 
> really pleased about this aproach.


> We could ask IBM for an Enhancement of the Preprocessor to accept the 
> Target "OPENCOBOL"


We could, but I'm guessing we would not get very far!  :-)   There is 
documentation on how to write your own DB2 pre-processor.  Dunno how 
difficult that might be, but it might be worth a shot.

> Sergey's comment to this was:
> OC will not work with stdcall and if stupid DB2 has only stdcall 
> library than it might be only choice to create (take from DB2) some 
> db2.h header file which will define those functions as stdcall, and 
> simply add the inclusion of this header to the libcob.h
> That should resolve the issue.


Cool.  Seems to work for me.
Here's my compile/link batch file:

cobc -fstatic-call -c checkerr.cbl -I"%DB2PATH%"\include\cobol_a
cobc -fstatic-call -c -x %1.cbl -I "%DB2PATH%"\include\cobol_a

link -debug -out:%1.exe %1.obj checkerr.obj "%DB2PATH%\lib\db2api.lib" 
C:\OpenCobol\libcob.lib C:\OpenCobol\gmp.lib
(the preceeding link is just a single line)

Seems to me that IBM COBOL for Micro Focus COBOL must use stdcall for 
all of their calls, which is why they use the sqlg_ functions, while 
OpenCOBOL uses C linkage (cdecl), and thus the problem.  Does this sound 
right?  Sounds like a job for the ENTRY-CONVENTION clause!

eg...

PROGRAM-ID. SQLGCALL IS PROTOTYPE AS 'sqlgcall'.
OPTIONS.
   ENTRY-CONVENTION IS STDCALL.
DATA DIVISION.
LINKAGE SECTION.
01  CALL-TYPE         BINARY-SHORT UNSIGNED.
01  SECTION-NBR       BINARY-SHORT UNSIGNED.
01  SQLDA-ID-IN       BINARY-SHORT UNSIGNED.
01  SQLDA-ID-OUT      BINARY-SHORT UNSIGNED.
01  RESERVED-PTR      POINTER.
01  RC                BINARY-LONG.
PROCEDURE DIVISION USING
               BY VALUE CALL-TYPE
                        SECTION-NBR
                        SQLDA-ID-IN
                        SQLDA-ID-OUT
                        RESERVED-PTR
              RETURNING RC.
END PROGRAM SQLGCALL.

Boy, that sure is a lot of typing for what seems such a simple thing! 
But that's COBOL for you...  Not sure if the above is even correct, but 
hey...

Anyway, I'll go with adding the following to libcob.h:
#include <sql.h>
#include <sqlaprep.h>

Thanks!

Frank