Article ID: 49383
Article Last Modified on 11/21/2006
This article was previously published under Q49383
SUMMARY
The two programs shown 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.
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 BNUMNEAR.BAS, which passes standard numeric types (by near reference) to assembly language routines:
DECLARE SUB Numint(i%)
DECLARE SUB Numlong(l&)
DECLARE SUB Numsng(s!)
DECLARE SUB Numdbl(d#)
i% = 2 ' Initialize values
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 assembler program is ANUMNEAR.ASM, which accepts standard numerics by near 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
mov bx, [bp+6]
mov ax, [bx] ; get integer
shl ax, 1 ; multiply by 2
mov [bx], ax ; put new value back
pop bp
ret 2
Numint ENDP
Numlong PROC
push bp
mov bp, sp ; set stack frame
mov bx, [bp+6]
mov cx, [bx] ; get long
mov ax, [bx+2] ; switch high and low words
mov [bx+2], cx ; put new value back
mov [bx], ax
pop bp
ret 2
Numlong ENDP
Numsng PROC
push bp
mov bp, sp ; set stack frame
mov bx, [bp+6]
or byte ptr [bx+2],80h ; Set sign bit
pop bp
ret 2
Numsng ENDP
Numdbl PROC
push bp
mov bp, sp ; set stack frame
mov bx, [bp+6]
or byte ptr [bx+6],80h ; Set sign bit
pop bp
ret 2
Numdbl ENDP
END
To demonstrate these programs from an .EXE program, compile and link as follows:
BC /O BNUMNEAR.BAS;
MASM ANUMNEAR.ASM;
LINK BNUMNEAR ANUMNEAR;
BNUMNEAR.EXE produces the following output:
BEFORE AFTER
Integer: 2 4
Long : 4 40000
Single : 3.4 -3.4
Double : 5.6000 -5.6000
Additional query words: QuickBas BasicCom
Keywords: KB49383
