Message-ID: <38A123D5.14EEA3A6@pacific.net.hk>
Date: Tue, 08 Feb 2000 08:22:45 -0800
From: ayoung <ayoung AT pacific DOT net DOT hk>
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Newsgroups: comp.os.msdos.djgpp
To: djgpp AT delorie DOT com
Subject: Re: Threads
References: <Pine DOT SUN DOT 3 DOT 91 DOT 1000207094939 DOT 17159H-100000 AT is>
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Reply-To: djgpp AT delorie DOT com

Thanks for this little insight as I over looking the importance of the int(0x31)

call within __djgpp_hw_exception.

The result of all this being that no existing DJGPP thread library could be
called real time, in fact there is the possibility of losing alarms etc if there
are high
delays within DPMI and/or DOS services.  Another option is to directly install
protect and real mode interrupt traps (i.e. not via DMPI) removing the
DMPI interrupt redirection **.

This allows two things:
    1)    Context switching within the timer interrupt (and others); and
    2)    The reprogramming of the timer rate (eg 1ms) as doing so involves
           emulating the DOS 18.x tick timer.

**    In truth more is involved as additional interrupts, a mix of h/w and s/w,
        must be monitored so not to context switch whilst within critical
        DMPI/DOS services.

Q:     How does the debugger interface with the application, and iIs there a
        document reference available ?   I ask as any rework of the interrupt
        construction will, most likely, effect this interface.

Cheers