Date: Mon, 8 Feb 93 09:50:02 EST
From: DJ Delorie <dj AT ctron DOT ctron DOT com>
To: dmb AT ai DOT mit DOT edu
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Replacing timer interrupt under DGJPP

>Is it possible to hook a C routine into the timer interrupt?  What I'm
>really trying to do is count vertical retraces without busy-waiting,
>but since not all VGA cards support vertical retrace interrupts I have
>to fake it with the timer.  The problem is that I have *no idea* how to
>make a C routine get called every timer tick from within a protected
>mode program.

The profiling code traps (or attempts to in 1.09) the timer interrupt.
That's in lib/gcrt0.s.

>Also, is there documentation anywhere on all the 386 GAS conventions?
>I keep seeing things like ".386p" and ".286c" that I'd really like to
>know how to use properly.  (I can kinda guess what those two mean, but
>there are surely other useful pseudo-ops.)

These two opcodes are not gas opcodes - they're tasm/masm codes.  If
what you're trying to understand has these codes, you need a tasm/masm
guide.

DJ