Example of Passing Array of Singles from Basic to MASM (49387)

SUMMARY

The two programs below demonstrate how a Microsoft Basic program passes an array of single precision numbers to assembly language by far reference.

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 BSINGLE.BAS, which creates an array of single-precision numbers, then passes the array to assembly language by far reference:

 DEFINT A-Z
   DECLARE SUB MasmSub (BYVAL segment, BYVAL offset, BYVAL number)

   'REM $DYNAMIC     'Can be either STATIC (the default) or DYNAMIC
   DIM s!(1 TO 10)   'Remove comment to define array DYNAMICally
   FOR i% = 1 to 10
      s!(i%) = i%
   NEXT
   CLS
   PRINT "Calling assembly routine to fill array elements..."
   CALL MasmSub(VARSEG(s!(1)), VARPTR(s!(1)), 10)
   PRINT "Values in array:"
   FOR i% = 1 TO 10
       PRINT s!(i);
   NEXT
   END

The following program is ASINGLE.ASM, which gets an array of single-precision numbers by far reference, then makes each number negative:

.MODEL MEDIUM
.CODE
        PUBLIC MasmSub
MasmSub PROC
        push bp
        mov bp, sp

        mov es, [bp+10]  ; get segment of array
        mov bx, [bp+8]   ; get offset of array
        add bx, 3        ; offset to byte holding sign bit
        mov cx, [bp+6]   ; get length of array
        mov al, 1

next:   or BYTE PTR es:[bx], 80h     ; set sign bit
        add bx, 4        ; increment counter to next array element
        loop next        ; loop to assign next array element
        pop bp
        ret 6
MasmSub ENDP
        END

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

BC BSINGLE.BAS;
MASM ASINGLE.ASM;
LINK BSINGLE ASINGLE;

BSTRF.EXE produces the following output:

Calling assembly routine to fill array elements...
Values in array: -1 -2 -3 -4 -5 -6 -7 -8 -9 -10