Article ID: 40884
Article Last Modified on 11/21/2006
This article was previously published under Q40884
SUMMARY
This article contains a sample Basic program that calls a Microsoft FORTRAN Version 4.10 subroutine, which passes a long-integer array. The array is passed to FORTRAN by FAR reference, allowing you to compile the FORTRAN subroutines with both medium- and large-memory models.
When passing an array to FORTRAN by FAR reference, the Basic program must use the VARSEG and VARPTR commands. The FAR keyword in FORTRAN requires that the variable segment (VARSEG) is passed as the first two bytes, and the offset (VARPTR) as the next two bytes.
MORE INFORMATION
The following Basic program and FORTRAN Version 4.10 subroutine has been tested with Microsoft QuickBasic Versions 4.00, 4.00b, and 4.50 and the Basic Compiler Versions 6.00 and 6.00b. The Basic compiler Versions 6.00 and 6.00b supports the alternate math (/FPa) in addition to the emulation math (/FPi), both of which have been successfully tested.
Both QuickBasic and the Basic compiler can produce stand-alone programs (compiled with the /o option) and programs that require a run-time library (compiled without the /o option). The following table has been produced to show the results of execution with these options.
Note: An "X" means the product worked correctly, and an "O" means the program failed to work correctly, possibly hanging the computer.
QuickBasic 4.00 4.00b 4.50
Stand-Alone X X X
Run-Time Library X X X
NOTE: When using QuickBasic, FORTRAN must be compiled with the /FPi math option because this is the only math option available to QuickBasic.
Basic Compiler 6.00 6.00b
/FPa Stand-Alone X X
/FPa Run-Time X X
/FPi Stand-Alone X X
/FPi Run-Time X X
As the above information shows, it is possible to pass a LONG INTEGER array by FAR reference to a FORTRAN subroutine.
When using a mixed-language program, you should not mix the math options between the different languages and between the subroutines of the same language.
The following are the compiling instructions:
BC file1;
FL /FPi /c /AL file2.for
LINK file1 file2 /NOE;
The above compiling instructions assume that FILE1.BAS is the Basic source file, and FILE2.FOR is the FORTRAN source filename. When invoking the FORTRAN compiler in the second step above, the filename and extension is used.
The FORTRAN subroutine can be compiled with the /AM (medium-model) compiler directive.
The following is the Basic source code:
DECLARE SUB forsub (BYVAL segvar%, BYVAL valvar%)
REM ** Passing the elements BYVAL is required. The first
REM ** element is the segment and the second element is the
REM ** offset. Using the INTEGER sign "%" after the variable
REM ** names ensures that two-bytes of information is being
REM ** passed, since the FAR keyword is being used in the FORTRAN
REM ** subroutine.
DIM heap%(2048)
COMMON SHARED /nmalloc/ heap%()
REM ** This is used to increase the amount of heap available to
REM ** the FORTRAN subroutine.
DIM PassInt&(10)
REM ** Array actual contains elements 0 through 10 which
REM ** make 11 values being passed in this example.
RANDOMIZE 32767
PRINT "Basic Language"
PRINT "=============="
FOR a& = 0 TO 10
PassInt&(a&) = INT(RND * 50000&)
PRINT PassInt&(a&),
NEXT a&
REM ** Load the array elements with random LONG INTEGER numbers
REM ** and print these numbers to the screen.
PRINT
CALL forsub(VARSEG(PassInt&(0)), VARPTR(PassInt&(0)))
REM ** Call the FORTRAN subroutine passing the segment (VARSEG)
REM ** and offset (VARPTR) of the first element of the array.
END
The following is the FORTRAN source code:
subroutine forsub(PassInt)
integer*4 PassInt [far] (11)
C ** Receive the array into a four-byte LONG INTEGER array of
C ** 11 elements, since the Basic array was from 0 through 10
C ** which makes 11 elements.
write (*,*) ' '
write (*,*) 'FORTRAN Language'
write (*,*) '================'
write (*,*) PassInt(1), PassInt(2), PassInt(3)
write (*,*) PassInt(4), PassInt(5), PassInt(6)
write (*,*) PassInt(7), PassInt(8), PassInt(9)
write (*,*) PassInt(9), PassInt(10), PassInt(11)
C ** Display the 11 elements to the screen to compare with
C ** what was displayed by the Basic program.
RETURN
END
The following is the output from the program:
Basic Language
37940 33524 13884 43346 27709
3244 147 10789 9183 19917
29339
FORTRAN Language
37940 33524 13884 43346
27709 3244 147 10789
9183 19917 29339
Additional query words: QuickBas BasicCom
Keywords: KB40884
