FIX: INVOKE May Cause Incorrect Line Information

The information in this article applies to:

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

SYMPTOMS

The Microsoft Macro Assembler (MASM) version 6.0 may generate line information that does not match the assembled code. When the parameters on an INVOKE statement are listed on more that one source line, line number information after the INVOKE might not match the assembled code. Incorrect line information will cause the assembler to show errors on the wrong lines. It also causes the CodeView debugger to appear to execute blank lines, comments, or wrong lines. In addition, it can cause problems setting breakpoints in CodeView.

RESOLUTION

To avoid this problem, put all of the parameters of an INVOKE call on the same line in the source code.

STATUS

Microsoft has confirmed this to be a problem in MASM version 6.0. This problem was corrected in MASM version 6.0a.

MORE INFORMATION

When the following sample code is run using CodeView, the debugger will appear to execute the wrong lines.

Sample Code

; Assemble options needed: /Zi

.MODEL small, c .STACK 4096

.DATA

Saaz        DW 1234h, 17h

.CODE hops PROC far C USES ax si di, boiling:ptr, finishing:ptr

    mov si, boiling
    mov di, finishing
    mov ax, [si]
    mov [di], ax
    mov ax, [si+2]
    mov [di+2], ax
    ret

    .startup
    mov ax, ds
    mov es, ax

    INVOKE  hops,
    offset Saaz,
    offset Hallertauer  ;CodeView appears to execute mov ax, Saaz here
                        ;and mov bx, Saaz+2 on this line.
    mov ax, Saaz
    mov bx, Saaz+2
    .exit 0