From:	bd733 AT rgfn DOT epcc DOT edu (Jason M. Daniels)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Callbacks
Date:	8 Jun 1997 17:44:42 GMT
Organization:	The Rio Grande Free-Net, El Paso Community College, El Paso, TX
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Message-ID:	<5ner2a$7o6@news.epcc.edu>
References:	<19970608160801 DOT MAA04618 AT ladder02 DOT news DOT aol DOT com>
NNTP-Posting-Host:	rgfn.epcc.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

Goretec3 (goretec3 AT aol DOT com) wrote:
> I was looing through the Allegro code to maye learn something and, as I
> looked through the mouse section, I saw a funciotn that installs a
> callback. What is a callback? 

A callback (and I am, perhaps dangerously, assuming you refer to RMCBs 
here) is a sort of interrupt handler you install under a DPMI host that 
will catch real mode interrupts (as opposed to only protected mode 
interrupts) and call the corresponding function back in protected mode. 
(For example, say I wanted to make a TSR, I'd need to hook INT 0x28 (DOS 
Idle) to do this. So, I'd allocate an RMCB (Real Mode CallBack) that 
would catch INT 0x28 signals in real mode, then call my protected mode 
handler.)

--
Jason Daniels -- bd733 AT rgfn DOT epcc DOT edu
---> BELIEVE THE LIE <---
Linux: The choice of a GNU generation.
Winblows 95: The world's best-selling computer virus.

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