From:	firewind <firewind AT phonebooth DOT dyn DOT ml DOT org>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Handling Interrupts
Date:	10 Aug 1997 23:21:52 GMT
Organization:	Netcom
Lines:	21
Message-ID:	<5slieg$agg@sjx-ixn7.ix.netcom.com>
References:	<33E74A35 DOT D5761524 AT tin DOT it>
NNTP-Posting-Host:	elp-tx2-04.ix.netcom.com
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Pancheri Paolo <darkangel AT tin DOT it> wrote:
> Whit the functions
> _go32_dpmi_get_protected_mode_interrupt_vector(0x08, &old_timer_handler)
> and _go32_dpmi_set_protected_mode_interrupt_vector(0x08,
> &new_timer_handler) I can save the old timer handler and install a my
> own handler. But how can I call the old handler (saved in
> old_timer_handler)?

Use something like this: (assuming old_int holds the seginfo for the old
interrupt)

__dpmi_regs call_regs;
call_regs.x.cs = old_int.rm_segment;
call_regs.x.ip = old_int.rm_offset;
call_regs.x.ss = call_regs.x.sp = 0;
__dpmi_simulate_real_mode_procedure_iret(&call_regs);

Assuming you're calling __d_s_r_n_p_i from inside an interrupt, you will
probably want to assign values to other registers of call_regs.

hth

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