From:	J-E Mikael B Segercrantz <segercra AT cc DOT helsinki DOT fi>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Line Drawing
Date:	5 Aug 1997 20:14:26 GMT
Organization:	University of Helsinki
Lines:	26
Message-ID:	<5s81j2$7dg$1@oravannahka.Helsinki.FI>
References:	<01bca164.ac490780$8553f7c7 AT humbug>
NNTP-Posting-Host:	kruuna.helsinki.fi
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

James T'seleie <tseleie AT yellowknife DOT com> wrote:
> I was wondering if anybody could give me a simple line drawing algorithm
> that works in DJGPP.  I wrote a program, that I thought would work, but it
> comes up with an error that I can't figure out.  Maybe someone could tell
> me what this means, and I could fix it myself.  Anyway, the error I get
> says something about a page fault at eip=00001691, and then a whole bunch
> of other sutuff that has to do with registers.  At the bottom of the
> message it says "call frame traceback EIPs: 0x00001691 and 0x00001bfe"  If
> anybody could offer some help with this it would be greatly appreciated. 
> Thanks.

Try, after the program crashes, to run symify.exe (came with DJGPP). 
This will show what function _probably_ caused the crash, and will help
you to locate the problem.

Symify is run with the name of the crashed program as argument, and it
needs to have the text DJGPP's stub dumped while crashing on the screen.

As for the page fault, I think it has to do with writing outside
graphics memory, in which case I'd suggest to add a little test to the
drawing function to check if this pixel is outside the screen or not.

-- 
- Mikael Segercrantz
  segercra AT cc DOT helsinki DOT fi
  http://www.helsinki.fi/~segercra/

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