Using Medium and Large Memory FORTRAN Models with Basic (40371)

SUMMARY

The information below applies to QuickBasic Versions 4.00, 4.00b, and 4.50, and Microsoft Basic Compiler Versions 6.00 and 6.00b for MS-DOS and OS/2.

This information also applies to Microsoft Basic PDS Version 7.00 for MS-DOS and MS OS/2, but only when using near strings. (For more information on using far strings in mixed-language programs, please refer to Chapter 13, "Mixed Language Programming with Far Strings," in the "Microsoft Basic 7.0: Programmer's Guide." Note that far strings are only available with Basic PDS 7.00.)

Variables in a FORTRAN subroutine may be specified as being [NEAR] or [FAR]. Likewise, QuickBasic can pass parameters to a subroutine by near or far reference. When parameters are passed as near and the FORTRAN subroutine is compiled under the medium memory model or the parameters are passed as far and the subroutine is compiled with the large memory model option, the variables are passed correctly.

MORE INFORMATION

The run-time error message "F2729 I/O item illegal in namelist I/O" is reported if you try to use far pointers while compiling in the medium memory model.

Example 1 below demonstrates a program that performs correctly when near parameters are used and the FORTRAN subroutine is compiled using the medium model (FL /AM) option. The parameters are passed incorrectly when the FORTRAN subroutine in Example 1 is compiled with the large model (FL /AL) option.

Example 2 is the equivalent program using the far option. Example 2 performs correctly when the FORTRAN subroutine is compiled with the large model option.

The following is Example 1, which uses the medium memory model:

   Compile in Basic as follows:     BC basprog/o;
   Compile in FORTRAN as follows:   fl /AM /APi /c forsub.for
   Link as follows:                 LINK basprog forsub/noe;

The following Basic program is BASPROG.BAS:

DECLARE FUNCTION MAKEIT$(S$,SIZE%)
DECLARE SUB DUM1(BYVAL S1%, BYVAL S2%, BYVAL S3%, BYVAL S4%)
DIM NAM%(3000)
COMMON /NMALLOC/ NAM%()
STR1$ = MAKEIT ("TEST OF PARAMETER VALUE PASSING" ,44)
STR2$ = MAKEIT ( "STRING 2" ,43)
STR3$ = MAKEIT ("STRING 3", 14)
STR4$ = MAKEIT ("STRING 4" ,14)
CALL DUM1(SADD(STR1$), SADD(STR2$), SADD(STR3$), SADD(STR4$))
END
FUNCTION MAKEIT$ (S$,SIZE%)
   MAKEIT$ = LEFT$(S$+STRING$(80, 32),SIZE%)
END FUNCTION

The following FORTRAN program is FORSUB.FOR:

      SUBROUTINE DUM1(STR1, STR2, STR3, STR4)
      CHARACTER*14 STR3, STR4 [NEAR]
      CHARACTER*43 STR1 [NEAR]
      CHARACTER*44 STR2 [NEAR]
      WRITE (*,*) STR1, STR2, STR3, STR4
      END

The following is Example 2, which uses the large memory model:

Compile in Basic as follows:    BC basprog/o;
Compile in FORTRAN as follows:  fl /AL /FPi /c forsub.for
Link as follows:                LINK basprog forsub/noe;

The following Basic program is BASPROG.BAS:

DECLARE FUNCTION MAKEIT$(S$,SIZE%)
DECLARE SUB DUM1(BYVAL S1%, BYVAL S2%, BYVAL S3%, BYVAL S4%,_
                 BYVAL S5%, BYVAL S6%, BYVAL S7%, BYVAL S8%)
DIM NAM%(3000)
COMMON /NMALLOC/ NAM%()
STR1$ = MAKEIT ("TEST OF PARAMETER VALUE PASSING" ,44)
STR2$ = MAKEIT ( "STRING 2" ,43)
STR3$ = MAKEIT ("STRING 3", 14)
STR4$ = MAKEIT ("STRING 4", 14)
CLS
LOCATE 10,1
CALL DUM1(VARSEG(STR1$),SADD(STR1$), VARSEG(STR2$),SADD(STR2$),_
          VARSEG(STR3$), SADD(STR3$), VARSEG(STR4$), SADD(STR4$) )
LOCATE 24,1
END
FUNCTION MAKEIT$ (S$,SIZE%)
   MAKEIT$ = LEFT$(S$+STRING$(80, 32),SIZE%)
END FUNCTION

The following FORTRAN program is FORSUB.FOR:

      SUBROUTINE DUM1(STR1, STR2, STR3, STR4)
      CHARACTER*14 STR3, STR4 [FAR]
      CHARACTER*43 STR1 [FAR]
      CHARACTER*44 STR2  [FAR]
      WRITE (*,*) STR1, STR2, STR3, STR4
      END