Date: Thu, 25 Jan 1996 04:22:32 -0500 (EST)
From: Cuthalion / Sliced Bread <enrico AT max DOT tiac DOT net>
To: djgpp AT delorie DOT com
Subject: Waiting for retraces........................................
Message-ID: <Pine.NEB.3.91.960125025624.2961A-100000@max.tiac.net>
MIME-Version: 1.0


	Okay, so I'm writing this 3d amination programme, and I need to 
wait for the vertical video retrace.  So I take some code from a friend's 
graphics library, and use it.  And it gets stuck in an infinite loop.  So 
I write my own, and the same thing happens.  And I double check and 
triple check and quadruple check my references, but it still doesn't 
work.  So I look at Csaba Beigl's code, and take parts from it, and it 
doesn't get stuck in a loop, but it doesn't wait for the retrace either.  

	Eventually I figured out what was wrong, after making a couple of 
really stupid mistakes (I tried a whole bunch of times, it stands to 
reason that some of the attempts will be really messed up.. :)   The 
problem was that I was using -O3.  Evidently, GCC took this to mean that 
I didn't expect the values of any hardware ports to change ever, and it 
was okay if it would cache them.  Is this a problem with GCC in general, 
or the port to the Intel chips?  (Can't it be told that some stuff, like 
hardware status, will change, without GCC changing it?)

/***********************************************************************
* Jesse Morris * cuth AT gryphon DOT ccs DOT brandeis DOT edu * jrmorris AT macalstr DOT edu *
****************   Cuthalion / Sliced Bread    *************************
              \*********************************/