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Linking ftn95 DLLs in a ftn95 exe

 
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hnoboa



Joined: 23 Feb 2009
Posts: 2
Location: Wisconsin, USA
PostPosted: Mon Feb 23, 2009 10:56 pm    Post subject: Linking ftn95 DLLs in a ftn95 exe Reply with quote
I am trying to learn how to link dlls in ftn95, so I made one file with this code:
Code:
   MODULE Variables
      IMPLICIT NONE
!      INTEGER, PARAMETER::IKIND = SELECTED_REAL_KIND(12,99)
      REAL :: a, b, c, x1, x2 !(KIND=IKIND)
    END MODULE Variables

PROGRAM Binomial
   USE Variables
    a=1
    b=1
    c=-12
    call RootsFinder
    call PrintResults(a,b,c,x1,x2)
    read *,a
 
END PROGRAM Binomial

a second file with this code:
Code:
    SUBROUTINE RootsFinder
    USE Variables
    REAL :: Disc !(KIND=IKIND)
    Disc = b**2-4.0*a*c
    IF (Disc > 0) THEN
      x1=(-b+sqrt(Disc))/(2*a)
      x2=(-b-sqrt(Disc))/(2*a)
    END IF
    END SUBROUTINE RootsFinder

These two files are compiled together using the Source Files in the project explorer. In this project, I also reference the dll created with the following code:
Code:
PROGRAM TEST
      IMPLICIT NONE
   INTERFACE
       SUBROUTINE PrintResults(a,b,c,x1,x2)
           REAL, INTENT(IN):: a,b,c,x1,x2
        END SUBROUTINE PrintResults
    END INTERFACE


CONTAINS

    F_STDCALL SUBROUTINE PrintResults(a,b,c,x1,x2)
!      INTEGER, PARAMETER::IKIND = SELECTED_REAL_KIND(12,99)
   IMPLICIT NONE
    REAL, INTENT(IN):: a, b, c, x1, x2 !, (KIND=IKIND)
    Print *, a,b,c
    print *, x1,x2
    END SUBROUTINE PrintResults


    F_STDCALL INTEGER FUNCTION LIBMAIN(hInst,ul,lpR)
   INTEGER hInst,ul,lpR
!***** Initialise global data here
   LIBMAIN=1
   END

END PROGRAM TEST

This third file is compiled by itself to generate the dll.

When I execute the exe, I get this:
Run-time error:
missing routine _printresults at 0x0....
in file clacvars.f95, at line 13 (the first file)

What am I missing? Could anybody direct me to a short clean example how to do this?

Thanks

Homero
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PaulLaidler
Site Admin


Joined: 21 Feb 2005
Posts: 7926
Location: Salford, UK
PostPosted: Tue Feb 24, 2009 8:37 am    Post subject: Reply with quote
There may be a few things to sort out here but to start with you do not need/want F_STDCALL if you are using FTN95 throughout.

If you do put it in then you need it at both ends (in the call as well as the definition) but this can be more tricky.
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hnoboa



Joined: 23 Feb 2009
Posts: 2
Location: Wisconsin, USA
PostPosted: Tue Feb 24, 2009 3:39 pm    Post subject: Reply with quote
Thanks Paul, I got it running!!
Thanks to your advise. The other main problem my dll had was that it had the subroutine inside the program, therefore was NOT external and could not be accessed by the main program. I made this change:

Code:
PROGRAM TEST
    IMPLICIT NONE
   INTERFACE
       SUBROUTINE PrintResults(a,b,c,x1,x2)
           REAL, INTENT(IN):: a,b,c,x1,x2
        END SUBROUTINE PrintResults
    END INTERFACE
   
END PROGRAM TEST

    SUBROUTINE PrintResults(a,b,c,x1,x2)
!      INTEGER, PARAMETER::IKIND = SELECTED_REAL_KIND(12,99)
   IMPLICIT NONE
    REAL, INTENT(IN):: a, b, c, x1, x2 !, (KIND=IKIND)
    Print *, a,b,c
    print *, x1,x2

END SUBROUTINE PrintResults


F_STDCALL INTEGER FUNCTION LIBMAIN(hInst,ul,lpR)
   INTEGER hInst,ul,lpR
!***** Initialise global data here
   LIBMAIN=1
END

and now it works.

I have another question for you. Is the LIBMAIN useful at all? In the help I read that I can use it to declare global variables. Could you explain how it works?
Thanks.
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PaulLaidler
Site Admin


Joined: 21 Feb 2005
Posts: 7926
Location: Salford, UK
PostPosted: Tue Feb 24, 2009 4:49 pm    Post subject: Reply with quote
If you do not use LibMain then leave it out and SLINK will provide it for you.

Sometimes programmers need to create global data the persists from one subroutine call to another and is shared between different subroutines. It is simpler and easier to avoid global data and to pass everything as arguments.
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