From:	Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Problem with interrupt handling
Date:	Mon, 6 Oct 1997 18:59:03 +0100
Organization:	None
Distribution:	world
Message-ID:	<L3qxJBAnbSO0Ewbw@talula.demon.co.uk>
References:	<3438C9AE DOT 2BBD AT art DOT alcatel DOT fr>
NNTP-Posting-Host:	talula.demon.co.uk
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Olivier PERRON writes:
>    _go32_dpmi_allocate_iret_wrapper(&info);
>    _go32_dpmi_set_protected_mode_interrupt_vector(0xF1, &info);
[snip]
>    __dpmi_int(0xF1, &r);

I've never tried hooking a software interrupt with djgpp, so I could be
totally wrong about this, but I think you are issuing that call in the
wrong way. The __dpmi_int() function calls the real mode interrupt
handler, but you have only installed a protected mode handler (according
to the DPMI spec, hardware interrupts are automatically reflected into
protected mode but software interrupts are not). I think you will need
to generate the interrupt directly by issuing an asm "int"
instruction...

If the goal of this program is to eventually make it hook a hardware
interrupt instead, you should be aware that calling printf() from an irq
routine is not a good idea!


--
Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
Beauty is a French phonetic corruption of a short cloth neck ornament.

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