From: Mark Slagell <bald_soprano AT geocities DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: What registers do I have to save when using external assembler functions?
Date: Mon, 09 Jun 1997 16:38:38 -0500
Organization: dept. of redundancy dept.
Lines: 19
Message-ID: <339C77DE.2E1@geocities.com>
References: <339c502e DOT 3723200 AT nntp DOT netcomuk DOT co DOT uk>
NNTP-Posting-Host: dial28.ppp.iastate.edu
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Precedence: bulk

I can't remember the answer, but you can find out by writing a simple C
function that requests too many register variables, say six.  Compile it
(unoptimized) with the -S switch, then see which registers get saved in
the resulting assembly code.

William McGugan wrote:
> 
> What registers do I have to save when using external assembler
> functions? I'm asking because my assembly functions crash with -O, and
> I thought it might be due to DJGPP using a register variable that was
> corrupted my asm functions.
> 
> I have declared all my global variables and external functions as
> volatile, but that doesn't seem to help.
> 
> Thanks.
> 
> William McGugan
> http://www.netcomuk.co.uk/~wmcgugan