Date:	Tue, 12 Oct 1999 10:10:20 +0200 (IST)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender:	eliz AT is
To:	Johnny Chan <jchan AT paclink DOT net>
cc:	djgpp AT delorie DOT com
Subject:	Re: Q: Want to know the starting address and size of my program
In-Reply-To:	<000401bf1432$f7656180$ae3d7a86@phoenix.com>
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Reply-To:	djgpp AT delorie DOT com
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On Mon, 11 Oct 1999, Johnny Chan wrote:

> Question: I would like to know the starting address and the size of my own
> program. Anyway I can find this piece of information out?

Please define ``starting address'' and ``size''.  A program consists of 
several sections: there's code, there's data, there's the heap, and a few 
others.  What exactly do you want to know, and for what purpose?

A helpful answer depends on this information.

> Does the format of COFF (format used in DJGPP) includes these pieces of
> info?

In general, some info is recorded in the COFF image, other pieces are 
determined at run time by the loader and the run-time environment.

> If yes, how and where I can find the location of the file header?

What file header do you refer to?

> Also, how can I find out the starting address of the program loader?

Again, please define ``starting address'' in this context.  Are you 
looking for the address of the entry point into the loader's code?  If 
so, it is recorded in the normal DOS .exe header of the program, since 
the loader is just a 16-bit real-mode DOS program.

> I assume this loader is located in DOS memory, isn't it?

If you want to reach the loader from within a running DJGPP program, then 
you can't: its space is reused for the transfer buffer, after the loader 
has done its job.

> Can my program
> (resided in extended memory) read this piece of DOS memory?

You can read this memory with dosmemget, but since it is used for the 
transfer buffer, you will get garbage: the startup code begins using the 
transfer buffer quite early, so by the time you get there, it's 
overwritten many times.

> What will happen
> if my program modify this loader? Does this affects the behavior of my own
> program's execution?

Nothing will happen.  But why do you need something like that?

> I am developing a system diagnostic program in protected mode for a
> motherboard. That's why the program has such 'unique' requirement.

It might help if you explain some more.  The above sounds as if you have 
already settled on some solution(s) to your problems, but you based the 
solution on incorrect assumptions.  It might be a good idea to post a 
description of your original problems.  Then someone might come up with 
ideas about how to solve them.

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