From:	"Steve Ball" <s DOT ball AT xtra DOT co DOT nz>
Newsgroups:	comp.os.msdos.djgpp
Subject:	longjmp() from interrupt handler
Date:	Thu, 16 Jul 1998 23:47:44 +1200
Organization:	Customer of Telecom Internet Services
Lines:	17
Message-ID:	<6okp9j$7p6$1@wolfman.xtra.co.nz>
NNTP-Posting-Host:	p52-m28-mdr1.dialup.xtra.co.nz
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

We are doing some investigating to see if it's worth porting our code to
DJGPP and ditching (crappy) Watcom 11.0 and Borland 3.1. I'm real keen, but
there's one problem I haven't been able to solve.

Some of the BIOS calls we use hang on some machines. To recover from this,
before executing the BIOS call, we set up a handler for the timer tick. If
the handler is not removed before its countdown reaches zero, it longjmp()s
the execution back to a known point which gets it out of the hung BIOS call.

None of this works in protected mode of course. Has anybody got any smart
ideas about how to recover from hung BIOS calls? Any help would be greatly
appreciated (but please use little words -- my DPMI understanding is not
real good :-) ).

Steve.

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