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From: "Michael Hartsough" <Michael-Hartsough@mediaone.net>
Subject: Re: Converting Ada Tasks To VxWorks Tasks?
Date: 2000/04/14
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"Robert A Duff" <bobduff@world.std.com> wrote in message
news:wccaeiwblzf.fsf@world.std.com...
>
> No, that's not quite right.  The choice is "arbitrary" by default, which
> means that the Ada run-time system can always pick the first one.  It is
> not (necessarily) random.  If you select the Priority_Queuing policy,
> then it's more deterministic: it always picks the first one (see
> D.4(14)).

The major problem I've got is that although there are several features
which get me nearly there, there's no feature that solves everything,
and I don't see a way of combining features to find a collective
solution.

There's a Select statement, but you can only use it with Pipes.
Pipes would be okay, but they run on top of VxWork message
queues and the messages aren't queued in priority order (okay,
you Do get a choice of two priorities. Normal and High, but I see
that as so restricted as to be useless). VxWorks implements
POSIX queues which have 32 priority levels, which would be
sufficient for my needs, but Pipes don't use them. So you can't
use the Select statement.

Semaphores have priority queues, but I haven't figured out a way
to implement a Select statement that'll use semaphores and be
able to handle a guarded accept without performing some sort
of polling.

Anyways, if anyone can provide me with some references to work that's
already been accomplished in this area I'd be mighty grateful.

Thanks,
                MJH