.MODEL directive causing problems

From: Stephan Wolf (stewo68_at_hotmail.com)
Date: 01/20/04 

Date: Tue, 20 Jan 2004 18:10:55 +0000 (UTC)

The MS C compiler 1.52 produces an .ASM file (-Fa option), which
causes problems when compiled using MASM 6.13 (also tried MASM 7.10).

We are actually experiencing two different problems:

- The original .ASM file compiles ok but the linker adds relocations
although there is absoluetly no need to. The actual instruction is:

        push OFFSET DGROUP:_Ac

Note that we use the -G3 C compiler option and thus the following gets
inserted in the .ASM file:

        .386p
        .387

- The above problem goes away when we remove the .MODEL SMALL
directive (generated by the C compiler). However, we then see the
following error message:

        error A2075: jump destination too far : by xyz byte(s)

Note that the C compiler marks all jumps "short", e.g.

        je SHORT $L1971

It seems correct that such jumps cannot be lengthened due to the
explicit SHORT attribute. However, MASM *does* lengthen these jumps if
".MODEL SMALL" is specified.

Our program is a 16-bit DOS TSR running on i386 and above. Is there
any undocumented magic that the ".MODEL" directive does?

Any help is greatly appreciated.

Stephan

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