Date:	Mon, 22 Feb 93 14:04:22 CST
From:	bobp AT hal DOT com (Bob Pendleton)
To:	dmb AT ai DOT mit DOT edu
Cc:	djgpp AT sun DOT soe DOT clarkson DOT edu
Subject:	Replacing arbitrary interrupt handlers

Is "ticks" declared to be "volatile?"

>	for (;;) {
>		if (ticks > 100)
>			break;
>	}

If not, it is probably being loaded into a register before the start
of the loop and you are testing the value of the register many many times.

>	for (;;) {
>		vsync();	/* wait for vertical blank */
>
>		if (ticks > 100)
>			break;
>	}

Of course the compiler doesn't know if you whacked "ticks" as a side effect
of calling "vsync()" so it reloads it after each call.

Just a guess...


				Bob P.

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