Microsoft KB Archive/38216
Article ID: 38216
Article Last Modified on 10/17/2003
- Microsoft Macro Assembler 5.0
- Microsoft Macro Assembler 5.1 Standard Edition
- Microsoft Macro Assembler 5.1a
- Microsoft Macro Assembler 6.0 Standard Edition
- Microsoft Macro Assembler 6.0a
- Microsoft Macro Assembler 6.0b
This article was previously published under Q38216
If a variable is referenced externally in an assembler routine in the following manner:
.model large, c .data EXTRN Var:WORD
and declared globally in a large model C program as follows:
the following error is generated:
This error occurs because the assembler would expect to find Var in the segment _DATA in DGROUP. The C declaration, however, will put var in the segment FAR_BSS, since it is an uninitialized global data item in the large memory model.
Note that the same is true for the compact memory model.
One way to eliminate this error is to initialize Var in the C code:
This will put it in the _DATA logical segment in DGROUP.
Another work-around is to delcare Var in the Assembly code so that the assembler would expect to find Var in FAR_BSS, as follows:
.model large, c .fardata? EXTERN Var:WORD
In addition, be sure to use a segment override to access Var:
MOV ax, SEG Var MOV es, ax MOV bx, es:Var
Additional query words: 5.00 5.10 5.10a 6.00 6.00a 6.00b