How to Pass a Basic COMMON Block to a FORTRAN 5.00 Subroutine (65884)

MORE INFORMATION

To program interlanguage calling between FORTRAN 5.00 and Basic PDS version 7.10, you must obtain the following application note from Microsoft Technical Support: (The FORTRAN 5.00 run-time libraries must be rebuilt as shown in this application note to be compatible with the Basic PDS 7.10 run-time libraries.)

The technique illustrated below shows how to pass a named Basic COMMON block to a FORTRAN subroutine. This technique will not work with unnamed Basic COMMON blocks. This technique will work only with FORTRAN version 5.00 because you must use a FORTRAN STRUCTURE...END STRUCTURE data type, which is not supported in earlier versions of FORTRAN.

The strategy is to pass the segment and offset of the first variable in the named Basic COMMON block as a parameter in the call to the FORTRAN subroutine. The FORTRAN subroutine should set up a STRUCTURE...END STRUCTURE type variable with the same format as the Basic COMMON block. The FORTRAN subroutine must receive this STRUCTURE type variable as a formal parameter.

Code Example

Below is the Basic program BASCOMMN.BAS that sets up the named COMMON block, initializes the values, and calls the FORTRAN subroutine:

   'BASCOMMN.BAS **********************************************
   DECLARE SUB FORSUB (BYVAL segment%, BYVAL offset%)
   COMMON SHARED /Example/ a%, b&, c!, d#
   CLS
   a% = 10
   b& = 2000
   c! = 30.3
   d# = 40.125
   PRINT
   PRINT "Hit any key to call the FORTRAN subroutine"
   SLEEP
   CALL FORSUB(VARSEG(a%), VARPTR(a%))
   LOCATE 8, 1: PRINT "back in basic"
   END
				

Below is the FORTRAN program FORCOMMN.FOR, which contains the subroutine Forub(). It sets up a STRUCTURE type variable similar to the corresponding named Basic COMMON block, and prints out the values:

C FORCOMMN.FOR   **********************************************
      SUBROUTINE FORSUB( VAR )
      STRUCTURE /BASCOMMON/ 
          INTEGER*2 A
          INTEGER*4 B
          REAL*4    C
          DOUBLE PRECISION D
      END STRUCTURE
      RECORD /BASCOMMON/ VAR
      PRINT *, VAR.A
      PRINT *, VAR.B
      PRINT *, VAR.C
      PRINT *, VAR.D
      END
				

Below is the Basic code for NEARHEAP.BAS, which allocates near heap space for the FORTRAN subroutine. If you are working inside the QuickBasic QB.EXE or QBX.EXE environment, compile this routine and put it into a Quick library along with the FORTRAN program. If you are compiling and linking into an .EXE program, put these lines in the source code of the Basic program or in a separate Basic .OBJ module in a .LIB library.

   ' NEARHEAP.BAS **********************************************
   DIM Heap%(2048)
   COMMON SHARED /NMALLOC/ Heap%()
				

Compile the FORTRAN program as follows:

   FL /c /AM FORCOMMN.FOR
				

To work inside the QuickBasic 4.50 QB.EXE environment, build the libraries as follows:

   BC NEARHEAP.BAS;
   LIB FORCOMMN.LIB+NEARHEAP+FORCOMMN;
   LINK /Q FORCOMMN.LIB, FORCOMMN.QLB,,BQLB45.LIB MLIBFER.LIB;
				

To compile and link from DOS, build the libraries the same way and compile and link BASCOMMN.BAS as follows:

   BC BASCOMMN;
   LINK /NOE BASCOMMN+FORCOMMN.LIB,,,BRUN45.LIB+MLIBFER.LIB ;
				

To work inside the Basic PDS 7.00 QBX.EXE environment, build the libraries as follows

   BC /Fs/FPi NEARHEAP;
   LIB FORCOMMN.LIB+NEARHEAP+FORCOMMN;
   LINK /Q FORCOMMN.LIB, FORCOMMN.QLB,,QBXQLB.LIB MLIBFER.LIB ;
				

and compile and link from DOS as follows:

   BC /Fs/FPi BASCOMMN;
   LINK /NOE BASCOMMN+FORCOMMN.LIB,,,BRT70EFR+MLIBFER.LIB ;
				

The output from the program is as follows:

   Hit any key to call the Fortran subroutine
                10
              2000
             30.300000
             40.125000000000000

   Back in Basic