ID Number: Q72849
6.00 | 6.00
MS-DOS | OS/2
buglist6.00
Summary:
When creating an exported function with the Microsoft Macro Assembler
(MASM) version 6.0, the EXPORT keyword can be used in a procedure
definition and MASM will automatically generate the correct .OBJ
record to add it to the export table for the .EXE (or DLL). This is
useful when creating a procedure in a DLL that is called from outside
the DLL, when creating a callback procedure in an .EXE, or when
defining a procedure as residing in an IOPL segment with OS/2.
However, there is a problem when the EXPORT keyword is used in the
latter case. When creating an IOPL function, you must declare the
number of words that will be required to hold the parameters for the
function. The operating system then uses this value to build the stack
that the IOPL function will run on. You normally do this by adding the
word count after the function name in the EXPORT section of the
associated .DEF file. For example, the .DEF file may contain the
following:
EXPORTS _Func 3
The problem results when you then use the EXPORT keyword in MASM for
the procedure definition for the IOPL function as follows:
Func PROC EXPORT, arg1:WORD, arg2:WORD, arg3:WORD
MASM will generate an EXPDEF (EXPort DEFinition) record that lists the
parameter word count as zero. If you then link with the .DEF file that
correctly lists the word count as three, the linker will return the
following error message:
fatal error L1126: conflicting pwords value
The sample code illustrates this situation. The only workaround in
this case is to change the EXPORT keyword in the procedure definition
to PUBLIC.
Microsoft has confirmed this to be a problem in MASM version 6.0. We
are researching this problem and will post new information here as it
becomes available.
Sample Code
-----------
TEST.ASM
--------
; Assemble options needed: none
.286
.MODEL large
.DATA
.CODE
Func PROC C EXPORT, arg1:PTR DWORD, arg2:WORD
Func ENDP
end Func
TEST.DEF
--------
; Module definition file for linking
NAME Test
EXPORTS
_Func 3