Q77260: Mixed FORTRAN/C with OS/2 DLLs: Example, Restrictions
Article: Q77260
Product(s): Microsoft Fortran Compiler
Version(s): 5.1
Operating System(s):
Keyword(s):
Last Modified: 04-MAY-2001
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The information in this article applies to:
- Microsoft FORTRAN compiler for OS/2, version 5.1
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SUMMARY
=======
It is not possible to link an OS/2 DLL (dynamic-link library) that contains both
FORTRAN and C object code. All OS/2 DLLs must contain code in only one
language.
From the same FORTRAN main program, it is possible to call a separate FORTRAN DLL
and a C DLL, but only if the C DLL has the C run-time library statically-linked
into the C DLL. If the C run-time library is linked-in dynamically, when linking
the executable with both CRTEXE.OBJ and FRTEXE.OBJ, some "L2025: Multiply
Defined Symbols" and one "L2029: Unresolved External" result.
From a FORTRAN statically linked executable, it is possible to call a FORTRAN
DLL, which in turn calls a C DLL. This is possible only if the C DLL has the C
run-time library statically-linked to the C DLL.
From a FORTRAN statically linked executable, it is not possible to call a C DLL
that calls a FORTRAN DLL. This will result in a protection violation on entry
into the FORTRAN DLL. It is also not possible to statically link in the FORTRAN
run-time library to a FORTRAN DLL because the necessary libraries are not
available.
Page 151 of the "Microsoft FORTRAN Advanced Topics Manual" for version 5.1 states
that mixed language programming is not recommended in conjunction with
multithread programs or dynamic-linked libraries. Any mixed language between
OS/2 DLLs is not considered a feature of the product, and therefore is not
generally supported.
MORE INFORMATION
================
The following project code example calls a FORTRAN DLL, which in turn calls a C
DLL. Upon returning to the FORTRAN main program, the C DLL is called again.
Description of the Files that Make Up the Project
-------------------------------------------------
File Description
---- -----------
CC.CMD Command file to create C DLL, FORTRAN DLL, and MAIN.EXE
MAIN.FOR Main FORTRAN program
MYSUB.FOR FORTRAN source code for FORTRAN DLL
MYFORT.DLL FORTRAN DLL
MYFORT.DEF Definitions file containing exports for C DLL
MYFORT.LIB Import library resulting from MYC.DEF
C.C C source code for C DLL
MYC.DLL C DLL
MYC.DEF Definitions file containing exports for C DLL
MYC.LIB Import library resulting from MYC.DEF
LLIBCDLL.LIB* Import library for static-linked C run-time library
LLIBCE.LIB* Static C run-time library
FRTEXE.OBJ* Startup code to be linked with (for using FORTRAN DLLs)
FRTDLL.OBJ* Startup code to be linked in all user-written DLLs
FRTLIB.DLL FORTRAN run-time DLL (previously created by the user)
FRTLIB.LIB Imports library corresponding to FORTRAN run-time DLL
(previously created by the user)
* Shipped with either FORTRAN 5.1 or C 6.0. The rest of the files listed above
are either created by the command file CC.CMD, or are listed below.
Command File and Source Code for the Project
--------------------------------------------
MAKEFILE Makefile to create C DLL, FORTRAN DLL, and MAIN.EXE
all: myfort.dll myc.dll main.exe
myfort.lib: myfort.def
implib myfort.lib myfort.def
myc.lib: myc.def
implib myc.lib myc.def
mysub.obj: mysub.for
fl /c /Zi /Od /MD mysub.for
myfort.dll: mysub.obj myc.lib
link mysub frtdll,myfort.dll,nul,/co /nod frtlib myc os2,myfort.def
copy myfort.dll c:\os2\dll
c.obj: c.c
cl /c /Zi /Od /AL /MD c.c
myc.dll: c.obj myfort.lib
link c,myc.dll,nul,/co /nod llibcdll os2,myc.def
copy myc.dll c:\os2\dll
main.obj: main.for
fl /c /Zi /Od /MD main.for
main.exe: main.obj myfort.lib myc.lib
link main frtexe,main,nul,/co /nod frtlib os2 myfort myc;
MAIN.FOR: Main FORTRAN program:
c---------------------------------
interface to subroutine subtest[c]
end
integer*4 ii
write(*,*) 'this is from the main program'
call dllsub(ii)
write(*,*) 'this is after the call ',ii
write(*,*) 'calling the c dll'
call subtest
write(*,*) 'back from the c dll'
end
c----------------------------------
MYSUB.FOR: FORTRAN source code for FORTRAN DLL:
c-----------------------------------
interface to subroutine subtest [c] ()
end
subroutine dllsub [loadds] (ii)
integer*4 ii
ii = 2.0
write(*,*) 'this is from myfort.dll'
call subtest()
end
c------------------------------------
MYFORT.DEF: Definitions file containing exports for C DLL:
;------------------------------------
LIBRARY MYFORT INITINSTANCE
DATA MULTIPLE
PROTMODE
EXPORTS
DLLSUB
;------------------------------------
C.C: C source code for C DLL.
/*-----------------------------------*/
#include <stdio.h>
void _loadds _export subtest()
{
int n,i;
n = 6;
i = 8;
printf("\nthis is a test in c\n");
printf("\n n is %d i is %d",n,i);
}
/*-----------------------------------*/
MYC.DEF: Definitions file containing exports for C DLL.
;------------------------------------
LIBRARY MYC INITINSTANCE
DATA MULTIPLE
PROTMODE
EXPORTS
_subtest
;------------------------------------
Additional query words: nofps kbinf 5.10
======================================================================
Keywords :
Technology : kbAudDeveloper kbFortranSearch kbZNotKeyword3 kbFORTRAN510OS2
Version : :5.1
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