Q49400: Example of Passing Two-Dimensional Fixed-String Array to MASM

Article: Q49400
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: 5-SEP-1990

The two programs shown below demonstrate how a Microsoft BASIC program
can pass a two-dimensional fixed-length string array to assembly
language.

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
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 for the following
word:

   BAS2MASM

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

The following BASIC program is BTWOFIX.BAS, which passes an
uninitialized two-dimensional array of fixed-length strings to an
assembly routine that initializes the array:

   DECLARE SUB TwoFix(BYVAL ASeg AS INTEGER, BYVAL AOff AS INTEGER)
   DIM FixArray(1 TO 2, 1 TO 3) AS STRING * 9
   CALL TwoFix(VARSEG(FixArray(1, 1)), VARPTR(FixArray(1, 1)))
   FOR row% = 1 TO 2
      FOR col% = 1 TO 3
         PRINT FixArray(row%, col%)
      NEXT
   NEXT
   END

The following program is ATWOFIX.ASM, which initializes a
two-dimensional array of fixed-length strings passed from BASIC:

; The following handy .MODEL MEDIUM,BASIC directive is found in MASM
; 5.10 but not in earlier versions:
.MODEL MEDIUM, BASIC
.DATA
        Fix11 DB 'String 11'     ; allocate string data
        Fix21 DB 'String 21'
        Fix12 DB 'String 12'
        Fix22 DB 'String 22'
        Fix13 DB 'String 13'
        Fix23 DB 'String 23'
.CODE
        PUBLIC TwoFix
TwoFix  PROC
        push bp
        mov bp, sp               ; set stack frame
        push es
        mov es, [bp+8]           ; segment of string array
        mov di, [bp+6]           ; offset of string array
        mov si, OFFSET Fix11     ; get offset to string data
        mov cx, 54               ; length of all string data
        rep movsb                ; copy string data to array
        pop es
        pop bp
        ret 4
TwoFix  ENDP
        END

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

     BC BTWOFIX.BAS;
     MASM ATWOFIX.ASM;
     LINK BTWOFIX ATWOFIX;

BTWOFIX.EXE produces the following output:

     String 11
     String 12
     String 13
     String 21
     String 22
     String 23

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