Q49385: Example Passing Numerics from BASIC to MASM by Far Reference

Article: Q49385
Product(s): See article
Version(s): 4.00 4.00b 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | B_BasicCom H_MASM S_QuickASM | mspl13_basic
Last Modified: 10-AUG-1990

The two programs below demonstrate how a Microsoft BASIC program can
pass standard numeric types to assembly language routines.

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.

For more information about passing other types of parameters between
BASIC and MASM, search in the Software/Data Library or the Microsoft
Knowledge Base for the following word:

   BAS2MASM

Code Example
------------

The following BASIC program is BNUMFAR.BAS, which passes standard
numeric types to assembly language routines:

   DECLARE SUB Numint(SEG i%)
   DECLARE SUB Numlong(SEG l&)
   DECLARE SUB Numsng(SEG s!)
   DECLARE SUB Numdbl(SEG d#)
   i% = 2
   l& = 4
   s! = 3.4
   d# = 5.6
   CLS

   PRINT "         BEFORE","AFTER"
   PRINT "Integer: ";i%,,
   CALL Numint(i%)
   PRINT i%

   PRINT "Long   : ";HEX$(l&),,
   CALL Numlong(l&)
   PRINT HEX$(l&)

   PRINT "Single : ";s!,
   CALL Numsng(s!)
   PRINT s!

   PRINT USING "Double : ##.####            ";d#,
   CALL Numdbl(d#)
   PRINT USING "##.####"; d#

   END

The following program is ANUMFAR.ASM, which accepts standard numerics
by far reference and alters their values:

; The following handy .MODEL MEDIUM,BASIC directive is found in MASM
; 5.10 but not in earlier versions:
.MODEL MEDIUM, BASIC
.CODE
        PUBLIC Numint, Numlong, Numsng, Numdbl
Numint  PROC
        push bp
        mov bp, sp        ; set stack frame
        push es
        mov es, [bp+8]    ; get seg
        mov bx, [bp+6]    ; get offset
        mov ax, es:[bx]   ; get actual integer
        shl ax, 1         ; multiply by 2
        mov es:[bx], ax   ; put back new value
        pop es
        pop bp
        ret 4
Numint  ENDP

Numlong PROC
        push bp
        mov bp, sp        ; set stack frame
        push es
        mov es, [bp+8]    ; get seg
        mov bx, [bp+6]    ; get offset
        mov cx, es:[bx]   ; get actual long
        mov ax, es:[bx+2] ; switch high and low words
        mov es:[bx+2], cx ; put back new value
        mov es:[bx], ax
        pop es
        pop bp
        ret 4
Numlong ENDP

Numsng  PROC
        push bp
        mov bp, sp        ; set stack frame
        push es
        mov es, [bp+8]    ; get seg
        mov bx, [bp+6]    ; get offset
        mov ax, es:[bx+2] ; get actual single
        or ah, 80h        ; set sign bit
        mov es:[bx+2], ax ; put back new value
        pop es
        pop bp
        ret 4
Numsng  ENDP

Numdbl  PROC
        push bp
        mov bp, sp         ; set stack frame
        push es
        mov es, [bp+8]     ; get seg
        mov bx, [bp+6]     ; get offset
        mov ax, es:[bx+6]  ; get actual double
        or ah, 80h         ; set sign bit
        mov es:[bx+6], ax  ; put back new value
        pop es
        pop bp
        ret 4
Numdbl  ENDP

        END

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

   BC /O BNUMFAR.BAS;
   MASM ANUMFAR.ASM;
   LINK BNUMFAR ANUMFAR;

BNUMFAR.EXE produces the following output:

            BEFORE     AFTER
   Integer:  2          4
   Long   :  4          40000
   Single :  3.4       -3.4
   Double :  5.6000    -5.6000

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