How to Declare Externals in MASM

ID Number: Q39523

5.00 5.10 | 5.10

MS-DOS | OS/2

Summary:

The following are the rules for declaring externals in MASM:

1. NEAR code labels must be declared in the code segment

from which they are accessed.

2. Although FAR code labels can be declared anywhere in the source

code, it is recommended they be declared outside of any segments.

You may declare them at the top of your program after the .MODEL

directive.

3. Any external data in the DGROUP data segment, must be declared in

the segment in which it is defined. You may need to create a dummy

data segment for the external declaration.

4. Data items declared in .FARDATA segment, that need to be referenced

as externals, should be declared out of any segments. Otherwise,

fixup-overflow errors may occur during linking. Note: This

conflicts with the rules indicated on Page 162 of "Microsoft Macro

Assembler Programmer's Guide" for Versions 5.x.