Sender:	nate AT cartsys DOT com
Message-ID:	<377FDF5C.CACE0BF2@cartsys.com>
Date:	Sun, 04 Jul 1999 15:25:32 -0700
From:	Nate Eldredge <nate AT cartsys DOT com>
X-Mailer:	Mozilla 4.08 [en] (X11; I; Linux 2.2.10 i586)
MIME-Version:	1.0
To:	djgpp AT delorie DOT com
Subject:	Re: DJGPP & registers
References:	<199907042018 DOT QAA11787 AT delorie DOT com>
Reply-To:	djgpp AT delorie DOT com

Batchex wrote:
> 
> Hi,
> 
> I'm curious about a couple of things :
> 1. Does DJGPP compiled programs use FS and GS registers in any way ?

The compiled code itself doesn't use them, but library functions may use
and change GS, and the _far* functions use and change FS.

> 2. Does DJGPP use register variables when optimizing is on ? If it
> does, what registers does it use ?

Whichever ones seem like a good idea to the optimizer.

If you want to know this so you know how to save registers, you might
take a look at:

http://www.delorie.com/djgpp/doc/ug/asm/calling.html

(Yes, I wrote it.)

> 3. Where are the manuals/docs for FSDB ? I can't seem to find it
> anywhere.

There aren't any AFAIK, references to them notwithstanding.  But Alt-H
is pretty helpful, and if you've ever used an assembly-level debugger
before, it should get you going.

If you want a source-level debugger, GDB is good (you can also debug
assembly with it, btw).  RHIDE is apparently quite good as well, though
I personally don't use it.
-- 

Nate Eldredge
nate AT cartsys DOT com

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