Sample Assembly Function Returning Single to Basic (64106)

SUMMARY

The two programs below demonstrate how an assembly language function can return a single-precision variable to a Microsoft Basic program.

This information about interlanguage calling applies to QuickBasic versions 4.00, 4.00b, and 4.50 for MS-DOS, to Microsoft Basic Compiler versions 6.00 and 6.00b for MS-DOS and MS OS/2, and to Microsoft Basic Professional Development System (PDS) versions 7.00 and 7.10 for MS-DOS and MS OS/2.

MORE INFORMATION

For more information about passing other types of parameters between Basic and MASM, search in the Microsoft Knowledge Base using the following word:

BAS2MASM

Code Example

The following Basic program is SFUNC.BAS, which displays a single-precision number returned from an assembly language function:

   DECLARE FUNCTION QPrint!
   FOR i% = 1 to 2
      PRINT QPrint!
   NEXT

The following program is ASING.ASM, which will return a single-precision number when called:

; The following handy .MODEL MEDIUM,Basic directive is found in MASM
; 5.10 but not in earlier versions:
.MODEL MEDIUM, Basic
.DATA
        singlenum dd 98.6

.CODE
        PUBLIC QPrint
QPrint  PROC FAR
        push bp
        mov bp, sp
        push si
        push di
        push es

        push ds         ; set es = ds
        pop es

        mov si, offset dgroup:singlenum
        mov di, [bp+6]  ; load value into address at bp+6

        mov cx, 4
        rep movsb

        mov ax, [bp+6]  ; load offset of temp value in ax and
        mov dx, ss      ; ss into dx

        pop es
        pop di
        pop si
        pop bp
        ret 2
QPrint  ENDP
        END

To demonstrate these programs from an .EXE program, compile and link as follows:

   BC IFUNC.BAS;
   MASM ASING.ASM;
   LINK IFUNC ASING;

IFUNC.EXE produces the following output:

   98.6
   98.6