From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: ada and robots
Date: 1997/06/23
Date: 1997-06-23T00:00:00+00:00 [thread overview]
Message-ID: <dewar.867078319@merv> (raw)
In-Reply-To: 5ollh0$el9$1@news.nyu.edu
Richard said
<<This is perhaps a case where the casts in C are more portable.
If you write
* ((volatile long *) some_address) |= some_expression;
it would be quite peculiar (and perhaps even be considered a bug) if the
compiler didn't respect the "long" type and generate the correspondingly
sized load and store instructions.
>>
I don't see this claim at all. The corresponding Ada code would be
identical semantically to the C code, and the same statement ("quite
peculiar .. perhaps even be considered a bug") would apply to the Ada.
But that was not the example, the example was where a single bit was flipped.
If we write x &= 1;
in C where x is a volatile variable, there is nothing in the C language
that indicates whether we get
word load/store
byte load/store
bit set instruction (quite reasonable to expect on x86)
I think that the semantics of Ada and C are identical here. The advantage
of Ada is that it is a little more clear that you are playing low level
games -- in particular the quoted C code, in which the volatility is buried
in low level implementation, is undesirable.
next prev parent reply other threads:[~1997-06-23 0:00 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-06-16 0:00 ada and robots Marin David Condic, 561.796.8997, M/S 731-93
1997-06-17 0:00 ` Joe Gwinn
1997-06-18 0:00 ` Jon S Anthony
1997-06-18 0:00 ` Brian Rogoff
1997-06-20 0:00 ` Robert Dewar
1997-06-23 0:00 ` Geert Bosch
1997-07-02 0:00 ` Robert Dewar
1997-06-23 0:00 ` Richard Kenner
1997-06-23 0:00 ` Robert Dewar [this message]
1997-06-25 0:00 ` Will Rose
1997-06-25 0:00 ` Jonathan Guthrie
1997-06-21 0:00 ` Nick Roberts
-- strict thread matches above, loose matches on Subject: below --
1997-07-02 0:00 Ada " Huy Vo
1997-07-04 0:00 ` Richard A. O'Keefe
1997-07-01 0:00 Huy Vo
1997-07-02 0:00 ` Wes Groleau
1997-06-30 0:00 Huy Vo
1997-07-01 0:00 ` Alan Brain
1997-07-11 0:00 ` Will Rose
1997-07-02 0:00 ` Mattias Sj�sv�rd
[not found] <867541382.23405@dejanews.com>
1997-06-29 0:00 ` John Howard
1997-06-26 0:00 Huy Vo
1997-06-27 0:00 ` nma123
1997-06-27 0:00 ` Wes Groleau
1997-06-27 0:00 ` Jon S Anthony
1997-06-27 0:00 ` Alan Brain
1997-06-27 0:00 ` Stephen Leake
1997-06-27 0:00 ` Wes Groleau
1997-06-27 0:00 ` Richard A. O'Keefe
1997-06-24 0:00 Huy Vo
1997-06-25 0:00 ` Wes Groleau
1997-06-25 0:00 ` Jon S Anthony
1997-06-25 0:00 ` Dale Stanbrough
1997-06-25 0:00 ` Alan Brain
1997-06-26 0:00 ` Ken Garlington
1997-07-01 0:00 ` Tom Moran
1997-06-20 0:00 Huy Vo
1997-06-23 0:00 ` Jon S Anthony
1997-06-19 0:00 ada " Jon S Anthony
1997-06-19 0:00 ` Brian Rogoff
1997-06-20 0:00 ` Jon S Anthony
1997-06-22 0:00 ` John G. Volan
1997-06-25 0:00 ` Richard A. O'Keefe
1997-06-23 0:00 ` Robert Dewar
1997-06-24 0:00 ` Brian Rogoff
1997-06-16 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-06-12 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-06-09 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-06-05 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-06-05 0:00 Marin David Condic, 561.796.8997, M/S 731-93
1997-06-09 0:00 ` Jerry Petrey
1997-06-10 0:00 ` Alan Brain
1997-06-10 0:00 ` Joe Gwinn
1997-06-11 0:00 ` Alan Brain
1997-06-11 0:00 ` Joe Gwinn
1997-06-11 0:00 ` Spam Hater
1997-06-11 0:00 ` Robert Dewar
1997-06-11 0:00 ` Samuel Mize
1997-06-13 0:00 ` Erik Magnuson
1997-06-17 0:00 ` Joe Gwinn
1997-06-18 0:00 ` Jon S Anthony
1997-06-19 0:00 ` Jonathan Guthrie
1997-06-20 0:00 ` Robert Dewar
1997-05-28 0:00 John Bohn
1997-05-29 0:00 ` Michael F Brenner
1997-05-29 0:00 ` Stephen Leake
1997-05-30 0:00 ` John Cook
1997-05-30 0:00 ` Tom Moran
1997-06-01 0:00 ` Dale Stanbrough
1997-06-02 0:00 ` John G. Volan
[not found] ` <5mv984$7kn@news.emi.com>
1997-06-03 0:00 ` Joe Gwinn
1997-06-04 0:00 ` Pat Rogers
1997-06-05 0:00 ` Joe Gwinn
1997-06-14 0:00 ` Robert Dewar
1997-06-16 0:00 ` Ken Garlington
1997-06-16 0:00 ` Robert Dewar
1997-06-17 0:00 ` Joe Gwinn
1997-06-28 0:00 ` Mike Stark
1997-07-03 0:00 ` Joe Gwinn
1997-06-04 0:00 ` John G. Volan
1997-06-05 0:00 ` Joe Gwinn
1997-06-14 0:00 ` Robert Dewar
1997-06-17 0:00 ` Joe Gwinn
1997-07-03 0:00 ` Shmuel (Seymour J.) Metz
[not found] ` <9706052229.AA29554@jaguar.nmc.ed.ray.com>
1997-06-06 0:00 ` John G. Volan
1997-06-07 0:00 ` RC
1997-06-09 0:00 ` Joe Gwinn
1997-06-05 0:00 ` Jon S Anthony
1997-06-05 0:00 ` Joe Gwinn
1997-06-14 0:00 ` Robert Dewar
1997-06-10 0:00 ` Robert Dewar
1997-06-10 0:00 ` Joe Gwinn
1997-06-11 0:00 ` Robert Dewar
1997-06-12 0:00 ` George Haddad
1997-06-16 0:00 ` Matthew S. Whiting
1997-06-17 0:00 ` Stephen Leake
1997-06-17 0:00 ` Robert A Duff
1997-06-20 0:00 ` jim granville
1997-06-21 0:00 ` Robert Dewar
1997-06-29 0:00 ` Matthew Heaney
1997-07-03 0:00 ` Shmuel (Seymour J.) Metz
1997-07-13 0:00 ` Robert Dewar
1997-06-17 0:00 ` Samuel Mize
1997-06-18 0:00 ` Steve O'Neill
1997-06-19 0:00 ` Anonymous
1997-06-19 0:00 ` Kenneth W. Sodemann
1997-06-20 0:00 ` Stephen Leake
1997-06-20 0:00 ` Robert Dewar
1997-06-17 0:00 ` Jon S Anthony
1997-06-17 0:00 ` Matthew S. Whiting
1997-06-18 0:00 ` Robert A Duff
1997-06-18 0:00 ` Jon S Anthony
1997-06-22 0:00 ` John G. Volan
1997-06-18 0:00 ` Samuel Mize
1997-06-18 0:00 ` Matthew S. Whiting
1997-06-17 0:00 ` Robert Dewar
1997-06-17 0:00 ` Robert A Duff
1997-06-18 0:00 ` Ken Garlington
1997-07-17 0:00 ` Shmuel (Seymour J.) Metz
1997-06-20 0:00 ` Adam Beneschan
1997-06-20 0:00 ` Robert Dewar
1997-06-03 0:00 ` Martin A. Stembel
1997-06-04 0:00 ` RC
1997-06-04 0:00 ` John G. Volan
1997-06-04 0:00 ` Larry Kilgallen
1997-06-05 0:00 ` Jon S Anthony
1997-06-02 0:00 ` Nick Roberts
1997-06-04 0:00 ` Jan Galkowski
1997-06-05 0:00 ` Albert K. Lee
1997-06-06 0:00 ` dana
1997-06-07 0:00 ` John G. Volan
1997-06-10 0:00 ` dana
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