FIX: L1101 Error Linking MASM Object Module w/ Large Structure

MS-DOS                      | OS/2

The information in this article applies to:

• Microsoft Macro Assembler for MS-DOS, versions 6.0, 6.0a, 6.0b, 6.1, and 6.1a
• Microsoft Macro Assembler for OS/2, versions 6.0, 6.0a, and 6.0b

SYMPTOMS

An attempt to link an application assembled with the Microsoft Macro Assembler (MASM) fails and the Microsoft Link utility (LINK) generates the following message:

   fatal error L1101: invalid object module

CAUSE

MASM generates an incorrect LIDATA record when the source code declares large data structures.

RESOLUTION

To work around this problem, organize structure initialization into a series of DUP directives, as shown below. If necessary, MASM processes the structure into several LIDATA records.

   msg_str STRUCT
   msg     BYTE 44 DUP(120), 10, 13
           BYTE 44 DUP(111), 10, 13
           BYTE 44 DUP(120), 10, 13
           BYTE 44 DUP(111), 10, 13
           BYTE 44 DUP(120), 10, 13
           BYTE 44 DUP(111), 10, 13
           BYTE 44 DUP(120), 10, 13
           BYTE 44 DUP(111), 10, 13
           BYTE 44 DUP(120), 10, 13
           BYTE '$'
   msg_str ENDS

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, 6.0b, 6.1, and 6.1a. This problem was corrected in MASM for MS-DOS version 6.11.

MORE INFORMATION

The code example below demonstrates this problem. Even though MASM is designed to create multiple LIDATA records for a data structure larger than 512 bytes, the assembler creates one LIDATA record for the entire data structure. When this occurs, the L1101 error occurs as indicated above.

See "The MS-DOS Encyclopedia" (Microsoft Press) for more information on the LIDATA record or other aspects of the object module format.

Sample Code

; Assemble options needed: none

.MODEL small .STACK 4096

.DATA msg_str STRUCT

msg     BYTE "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 10, 13
        BYTE "oooooooooooooooooooooooooooooooooooooooooooo", 10, 13
        BYTE "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 10, 13
        BYTE "oooooooooooooooooooooooooooooooooooooooooooo", 10, 13
        BYTE "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 10, 13
        BYTE "oooooooooooooooooooooooooooooooooooooooooooo", 10, 13
        BYTE "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 10, 13
        BYTE "oooooooooooooooooooooooooooooooooooooooooooo", 10, 13
        BYTE "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx", 10, 13
        BYTE '$'

struct_str msg_str 2 DUP (<>)

.CODE main PROC

   mov ax, @DATA
   mov ds, ax

   mov ah, 9h                    ; Request DOS Function 9.
   mov dx, OFFSET struct_str.msg ; Load DX with offset
                                 ; (segment already in DS).
   int 21h                       ; Display String.

   mov ax, 4c00h
   int 21h