FIX: Using a Higher Processor Directive in a Macro Causes A2006

MS-DOS           | OS/2

The information in this article applies to:

• Microsoft Macro Assembler for MS-DOS, version 6.0, 6.0a, and 6.0b
• Microsoft Macro Assembler for OS/2, version 6.0, 6.0a, and 6.0b

SYMPTOMS

When you attempt to use a symbol in your assembly code without defining it first, the Microsoft Macro Assembler (MASM) generates the following error:

      error A2006: undefined symbol : 'identifier'

RESOLUTION

To work around the problem, declare a processor type of sufficient level to execute the instructions in the macro before calling the macro. The comment in the sample code below demonstrates this by declaring the .286 directive before the macro is called.

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, and 6.0b. This problem was corrected in MASM for MS-DOS version 6.1.

MORE INFORMATION

The sample code below may be used to illustrate this problem. The default processor directive is .8086. When the macro is called, a LEAVE instruction is used that requires the .286 processor. However, with the .286 directive in the macro definition, the following error is generated by the assembler:

   file.asm(14): error A2006: undefined symbol : s
    my_proc(2): Macro Called From
     file.asm(14): Main Line Code

Sample Code

;Assemble options needed: /c

.MODEL small .8086

;.286    ;Uncomment this directive for workaround.

   .286
   enter s, 0
   .8086

.STACK 4096

.CODE start:

   my_proc 5
   mov ax, 4C00h
   int 21h