Date: Mon, 13 Dec 1999 10:35:10 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: Gerald Hilderink <g DOT h DOT hilderink AT el DOT utwente DOT nl>
cc: djgpp AT delorie DOT com
Subject: Re: returning from interrupt with iret?
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On Sun, 12 Dec 1999, Gerald Hilderink wrote:

> How can I program an inline "iret" assembly instruction in an interrupt
> service routine (isr) that is registered by the dpmi protected mode
> interface?

If the ISR is coded in assembly, simply use IRET ;-).

If it is coded in C, you should be using one of the _go32_dpmi_*
functions to install it as an ISR, and the _go32_dpmi_* functions do
an IRET for you.

> I need to enforce an iret to perform a context switch in the isr.

I don't understand what that means, in particular, what kind of
``context switch'' are you talking about.  Some kinds of ``context
switch'' are impossible in the DPMI environment (prohibited by the
DPMI spec).

> Is there technical information available about the _go32_dpmi functions?

The docs in libc.info, and the source code in djlsr202.zip.  If
something is still unclear, please ask here.