Sender: bukinm AT SunKEDR30 DOT inp DOT nsk DOT su
To: djgpp AT delorie DOT com
Subject: Re: Question about debugging
References: <Pine DOT SUN DOT 3 DOT 91 DOT 980728104439 DOT 4133B-100000 AT is>
	<p6tu3429of4 DOT fsf AT SunKEDR30 DOT inp DOT nsk DOT su>
From: M DOT A DOT Bukin AT inp DOT nsk DOT su
Date: 28 Jul 1998 19:35:19 +0700
In-Reply-To: bukinm@inp.nsk.su's message of 28 Jul 1998 18:59:27 +0700
Message-ID: <p6tr9z69mrc.fsf@SunKEDR30.inp.nsk.su>
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Precedence: bulk

Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> writes:

> On Sat, 25 Jul 1998, Victor wrote:
> 
> > I'd appreciate if someone could give me some idea how to debug my
> > code.
> >
> > Exiting due to signal SIGILL
> > Invalid Opcode at eip=00aeacac
> 
> This EIP is bogus.  AFAIK, a valid EIP cannot be more than EBP,
> because the stack is above the code in the DJGPP memory layout.  So
> you need to find out how did that EIP happen.

Very likely crash occurs inside stretch_blit.  stretch_blit allocates
memory for stretcher code.  I think, this can explain EIP higher than
EBP and other registers close to EIP.

I'd suggest to examine values passed to stretch_blit.  Allegro
documentation says that it can not handle stretching from outside
of source bitmap and between color-depths and also it can not blit
between NULL bitmaps.