Date: Wed, 9 Nov 1994 10:53:19 -0500 (EST)
From: Long Doan <ldoan1 AT mason1 DOT gmu DOT edu>
Subject: Re: A question about writing interrupt handler in gcc
To: Chih-Hao Tsai <c-tsai4 AT uiuc DOT edu>
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu

On Wed, 9 Nov 1994, Chih-Hao Tsai wrote:

> handler in gcc. When writing protected mode interrupt
> handler, one can use 
> _do32_dpmi_chain_protected_mode_interrupt_vector
> However, there is no real mode counterparts for this
> function call. I tried to use _go32_dpmi_simulate_fcall_iret
> to call the old handler, but it didn't work.
  
  Try to use go32_dpmi_simulate_int (). Or if that is causing too much 
overhead (Like when you're taking the int 08 vector, and speed the timer 
up about 1000 times/sec,) you can look at the disassembled code of _go32...
(using a debugger or whatever,) and insert that directly to your 
interrupt handler after stripping off some unnecessary codes.   

> Can anybody tell me how to chain original hanlder in
> a real mode interrupt handler? I've tried a thousand
> times.
  
  Another 1000 times wouldn't hurt...

> By the way, I've read the file 'dpmi.c' and couldn't
> figure out why there isn't a 
> 
> _go32_dpmi_chain_real_mode_interrupt_vector.
>                  ^^^^

  Because the DPMI specs don't include a chain real mode interrupt.


+--------------------------------------------------------+
| Long Doan                        ldoan1 AT mason1 DOT gmu DOT edu |
|                                          ld AT netrix DOT com |
+--------------------------------------------------------+