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Mail Archives: djgpp/1997/05/21/01:32:19

From: mert0407 AT sable DOT ox DOT ac DOT uk (George Foot)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Strange Allegro related crash
Date: 20 May 1997 19:35:01 GMT
Organization: Oxford University, England
Lines: 37
Message-ID: <5lsud5$2s3@news.ox.ac.uk>
References: <5lrd29$p5b AT freenet-news DOT carleton DOT ca>
NNTP-Posting-Host: sable.ox.ac.uk
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Paul Derbyshire (ao950 AT FreeNet DOT Carleton DOT CA) wrote:

: My project implements a double-buffer, using two pages of a three page
: Mode X screen for page flipping and the third stores a background image
: (so the parallaxing can be done mostly with fast latch-register blits).

(bug description snipped)

I haven't a clue what the problem is, but try the following: 

1) If you can remember what change you made before recompiling, go over it
with a fine-tooth comb. In particular, look into how it would affect the
screen updates.

2) Comment out unimportant sections of your code until you are left with
just the screen display routines (you may need to replace the
commented-out sections with `dummy' code to simulate sensible results),
and see if the bug remains. If so, you have dramatically reduced the
volume of code you need to check for bugs.

3) If not, put things back in one by one, or in groups where necessary,
until it resurfaces. Then you know almost exactly which section of your
code is causing the bug.

4) If the `culprit' section doesn't seem to be at fault itself, maybe it
is a bug in Allegro, or a slight error in the way you are using it; repost
then with more specific details

Doing the above should help you break the problem down, anyway, and maybe
you can provide a small working program which demonstrates the bug, which
you could then send to Shawn (if he has time to look through it).

-- 
George Foot <mert0407 AT sable DOT ox DOT ac DOT uk>
Merton College, Oxford

What's the wizard's password for? (dunnet)

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