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Q94577: Creating 32-Bit Flat Memory Model MASM Code for OS/2 2.0

Article: Q94577
Product(s): Microsoft Macro Assembler
Version(s): MS-DOS:6.0,6.0a,6.0b
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

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The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 6.0, 6.0a, 6.0b 
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SUMMARY
=======

Versions 6.0, 6.0a, and 6.0b of the Microsoft Macro Assembler (MASM) provide the
.MODEL flat directive to support generating 32-bit flat memory model
applications. When combined with the LINK386 utility and DOSCALLS.LIB library
provided with OS/2 version 2.0, you can generate a 32-bit flat memory model
application for the OS/2 version 2.0 environment.

To build a 32-bit flat memory model application for OS/2 2.0, perform the
following four steps:

1. Place the INCLUDELIB DOSCALLS.LIB directive in each source module that
  contains a call into the OS/2 2.0 application programming interface (API).
  DOSCALLS.LIB is the OS/2 2.0 import library that supports application calls
  to the operating system.

2. Place the .386 or .486 directive before the .MODEL flat, syscall directive to
  ensure that your code and data segments are set up correctly for a 32-bit
  flat memory model application. The order in which these two directives appear
  in the source code is important.

3. Specify the /c assembler option flag on the assembler command line to prevent
  MASM from invoking its 16-bit linker.

4. Link the object files using LINK386 distributed with OS/2 2.0. If LINK386
  cannot find the DOSCALLS.LIB file, specify the path to the library.

MORE INFORMATION
================

The LINK386 utility and DOSCALLS.LIB library are provided by IBM with OS/2
version 2.0. MASM versions 6.0, 6.0a, and 6.0b does not include either the
required library support for OS/2 operating system calls or a linker capable of
producing flat memory model applications. For more information on LINK386,
DOSCALLS.LIB, or the functions of the OS/2 2.0 API, please contact IBM.

LINK386 may generate two warnings that can be safely ignored:

  LINK386: warning L4071: application type not specified:

  assuming WINDOWCOMPAT

  LINK386: warning L4071: no automatic data segment

MASM version 6.1 does not run with any version of OS/2 including a DOS window
under OS/2. Microsoft does not support using MASM 6.1 for OS/2. Even though code
generated by MASM 6.1 running with MS-DOS may link with LINK386, Microsoft does
not support generating code in this manner.

Some of the products included here are manufactured by vendors independent of
Microsoft; we make no warranty, implied or otherwise, regarding these products'
performance or reliability.

Sample Code
-----------

  ; Assemble options needed: /c

  INCLUDELIB DOSCALLS.LIB

  .386
  .MODEL flat, syscall

  Dos32Write PROTO NEAR32 syscall,
      hf:WORD, pvBuf:NEAR32, cbBuf:WORD, pcbBytesWritten:NEAR32

  Dos32Exit PROTO NEAR32 syscall,
      fTerminate:WORD, ulExitCode:WORD

  .STACK 4096

  .DATA

  msg DB "Hello, world.", 13, 10
  written DW 0

  .CODE
  _start:
      INVOKE  Dos32Write,        ; OS/2 system call
          1,                     ; File handle for screen
          NEAR32 PTR msg,        ; Address of string
          LENGTHOF msg,          ; Length of string
          NEAR32 PTR written     ; Bytes written

      INVOKE  Dos32Exit,         ; OS/2 system call
          0,                     ; Terminate all threads
          0                      ; Result code for parent process

  END _start

Additional query words: kbinf 6.00 6.00a 6.00b 6.10

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM600 kbMASM600a kbMASM600b
Version           : MS-DOS:6.0,6.0a,6.0b

=============================================================================

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