From: DavMac AT iname DOT com (Davin McCall)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: newbie interrupt programmer
Date: Sun, 23 May 1999 12:17:49 GMT
Organization: Monash Uni
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Reply-To: djgpp AT delorie DOT com

There is one other problem I didn't have too much trouble spotting.
(you really *are* new to this, aren't you...)

You can't just create a function and set it up as an interrupt
handler. This is because normal functions
a) don't save register values and
b) don't return using 'iret'

You need to create a wrapper function, using:

_go32_dpmi_allocate_iret_wrapper()

Also, how are you locking the code/data? If you must code the handler
in C (instead of assembly, which is preferable), the only really
guarenteed way of locking functions is to lock *all* code.

I stress that you should obtain a copy of FAQ and read carefully and
completely the related sections.

Davin.


On Fri, 21 May 1999 12:26:04 -0500, Mark Phillips
<umphill5 AT cs DOT umanitoba DOT ca> wrote:

>
>hmm, well i guess my interrupt wasn't getting called. 
>i realised my irq settings were wrong and i changed 
>those.  now, the sound will play, and when it's done,
>i get a SIGSEGV GPF.  i assume the interrupt function
>is getting called now and something in it is doing 
>bad things.  here is the function again:
>
>static void interrupt_handler()
>{
>   inportb(interptAcknowlg8);	// sb acknowledge
>   donePlaying = true;
>   outportb(0x20,0x20);		// acknowledge interrupt
>   outportb(0xA0,0x20);
>}
>
>it looks ok to me.  i'm pretty sure i locked 
>down all of the relevant code/variables. i just
>locked interptAcknowlg8, donePlaying, and then 
>the function code itself.  do i have to lock 
>inportb and outportb and anything they call
>too? i looked at the faq, and the only thing i 
>could find that might be helpful was "do all 
>the other chores described in the DPMI spec" 
>which i don't think i did, but when i looked at 
>the spec i couldn't really see where it said 
>what i was supposed to do. the message when it 
>crashes is this:
>
[snip]
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