From: gwinn@res.ray.com (Joe Gwinn)
Subject: Re: Beware: Rep spec on an enumeration type causes code explosion
Date: 1997/12/12
Date: 1997-12-12T00:00:00+00:00 [thread overview]
Message-ID: <gwinn-1212971935370001@dh5055236.res.ray.com> (raw)
In-Reply-To: 3490252D.6B550F17@ac3i.dseg.ti.com
In article <3490252D.6B550F17@ac3i.dseg.ti.com>, johnv@ac3i.dseg.ti.com wrote:
> Ken Garlington wrote:
[snip]
> My feeling is that "holey" enumeration types (like other Chapter 13
> features) should really only be used at the "edges" of a program,
> wherever you're immediately reading from or writing to some external
> system that is expecting a certain data format. Contiguous enumeration
> types should be used internally everywhere else in your program, for all
> the efficiency reasons that have been ... enumerated :-) ... in this
> thread. Luckily, Ada provides this convenient way of converting between
> holey and contiguous representations.
I have to disagree somewhat. We were using enumeration types as message
type IDs all over the place, not just at the edges. For safety-critical
messages, the enumerations are not permitted to be numerically contiguous,
being required to differ in at least four bits from all other message type
integer codes. This 4-bit requirement is intended to greatly reduce the
probability of message spoofing. (I know this isn't by itself
sufficient. This isn't the entire defense, only the part relevant to the
current issue.)
Joe Gwinn
next prev parent reply other threads:[~1997-12-12 0:00 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-12-05 0:00 Beware: Rep spec on an enumeration type causes code explosion Joe Gwinn
1997-12-06 0:00 ` Kevin D. Heatwole
[not found] ` <dewar.881478386@merv>
1997-12-07 0:00 ` Robert Dewar
1997-12-09 0:00 ` Jim Gleason
1997-12-06 0:00 ` Tucker Taft
1997-12-06 0:00 ` Robert Dewar
1997-12-06 0:00 ` Robert Dewar
1997-12-08 0:00 ` Joe Gwinn
1997-12-08 0:00 ` Mats Weber
1997-12-09 0:00 ` Geert Bosch
1997-12-10 0:00 ` Robert Dewar
1997-12-09 0:00 ` Tucker Taft
1997-12-09 0:00 ` Matthew Heaney
1997-12-10 0:00 ` Charles Hixson
1997-12-10 0:00 ` Robert Dewar
1997-12-10 0:00 ` Jean-Pierre Rosen
1997-12-10 0:00 ` Ken Garlington
1997-12-11 0:00 ` John G. Volan
1997-12-11 0:00 ` Ken Garlington
1997-12-12 0:00 ` Matthew Heaney
1997-12-12 0:00 ` Ken Garlington
1997-12-16 0:00 ` John G. Volan
1997-12-17 0:00 ` Ken Garlington
1997-12-12 0:00 ` Alan E & Carmel J Brain
1997-12-12 0:00 ` Robert Dewar
1997-12-15 0:00 ` Tucker Taft
1997-12-16 0:00 ` Brian Rogoff
1997-12-12 0:00 ` Joe Gwinn [this message]
1997-12-12 0:00 ` Robert Dewar
1997-12-16 0:00 ` John G. Volan
1997-12-17 0:00 ` Joe Gwinn
1997-12-17 0:00 ` John G. Volan
1997-12-18 0:00 ` Joe Gwinn
1997-12-17 0:00 ` Ken Garlington
1997-12-10 0:00 ` Stanley R. Allen
1997-12-14 0:00 ` Robert Dewar
1997-12-10 0:00 ` Stephen Leake
1997-12-14 0:00 ` Robert Dewar
1997-12-11 0:00 ` Rakesh Malhotra
1997-12-11 0:00 ` Matthew Heaney
1997-12-12 0:00 ` Robert Dewar
1997-12-12 0:00 ` Samuel Tardieu
1997-12-12 0:00 ` Robert Dewar
1997-12-12 0:00 ` Rakesh Malhotra
1997-12-14 0:00 ` Alan E & Carmel J Brain
1997-12-12 0:00 ` Joe Gwinn
1997-12-15 0:00 ` Robert Dewar
1997-12-16 0:00 ` Joe Gwinn
1997-12-16 0:00 ` Robert Dewar
1997-12-06 0:00 ` David Marshall
1997-12-06 0:00 ` Robert Dewar
1997-12-06 0:00 ` Matthew Heaney
1997-12-10 0:00 ` GNORT information ( Was Re: Beware: Rep spec on an enumeration type causes code explosion ) Mark Bennison
1997-12-10 0:00 ` Robert Dewar
1997-12-06 0:00 ` Beware: Rep spec on an enumeration type causes code explosion Robert Dewar
1997-12-08 0:00 ` Joe Gwinn
1997-12-06 0:00 ` Robert Dewar
1997-12-06 0:00 ` Robert Dewar
1997-12-08 0:00 ` Joe Gwinn
1997-12-09 0:00 ` Stanley R. Allen
1997-12-06 0:00 ` Robert Dewar
1997-12-06 0:00 ` Corey Minyard
1997-12-08 0:00 ` Joe Gwinn
1997-12-10 0:00 ` Robert Dewar
1997-12-06 0:00 ` Ken Garlington
1997-12-07 0:00 ` Larry Kilgallen
-- strict thread matches above, loose matches on Subject: below --
1997-12-09 0:00 tmoran
1997-12-11 0:00 Marin David Condic, 561.796.8997, M/S 731-96
1997-12-11 0:00 Marin David Condic, 561.796.8997, M/S 731-96
1997-12-11 0:00 ` Robert Dewar
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