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From: jtliu@phoenix.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Borland / Turbo C
Message-ID: <723@phoenix.PRINCETON.EDU>
Date: Thu, 17-Sep-87 01:05:00 EDT
Article-I.D.: phoenix.723
Posted: Thu Sep 17 01:05:00 1987
Date-Received: Sat, 19-Sep-87 07:49:32 EDT
References: <7871.1684.forumexp@mts.rpi.edu>
Reply-To: jtliu@phoenix.UUCP (James T. Liu)
Organization: Princeton Univ. Computing and Information Technology
Lines: 42
Summary: Large memory model link problems

In article <7871.1684.forumexp@mts.rpi.edu> Howard Kapustein writes:
>
>   According to BYTE magazine, Turbo C has a problem linking
>   large memory models. I think the problem was they didn't
>   compile right. How can I tell if my copy is bad (I purchased
>   it late-July.) I have not used large models yet, so I don't
>   know if I'm affected. I don't have the infamous inverted division error
>   ( 4/2 = .5). 
>...

I don't know if this link problem has been brought up before, but I ran
into this when compiling a large program.  Apparantly, the problem occurs
when linking (compiling is not a problem) large memory model programs
using the emulator library (emu.lib).  This is what I have been able to
figure out:

Routine fpexcep in the emulator library calls _exit (which is defined in
the main library, cl.lib) with a near call.  This means fpexcep and
_exit has to be loaded within 64K of each other.  The problem occurs
because fpexcep resides in segment _TEXT which is defined in c0l.obj and
thus occurs at the beginning of the executable.  However, _exit is
defined in EXIT_TEXT in library cl.lib, and this does not get loaded
until externals are resolved by the linker.  This means, _exit gets
loaded after all of your program modules.  Thus, if your program
code is longer than 64K, you'll run into this bug.  I believe the linker
reports 'fixup offset exceeds field width in module fpexcep', or
something like that.

I've found a simple way to fix this.  All you have to do is to assemble
the following file:

exit_text	segment para public 'code'
exit_text	ends
		end

and include this right after c0l (which should be the first file linked).
What this does is to force segment EXIT_TEXT to be loaded right after
segment _TEXT, thus forcing fpexcep and _exit to be within 64K of each
other.  I believe this works, but I really haven't tested it that
extensively.

						- Jim Liu (DEI)