From: Stephen Leake <stephen_leake@stephe-leake.org>
Subject: Re: GNAT 4.4.5 Record Bit_Order Endian issues
Date: Tue, 22 Jan 2013 20:38:59 -0500
Date: 2013-01-22T20:38:59-05:00 [thread overview]
Message-ID: <85pq0wadak.fsf@stephe-leake.org> (raw)
In-Reply-To: kdn4g3$od1$1@munin.nbi.dk
"Randy Brukardt" <randy@rrsoftware.com> writes:
> "Stephen Leake" <stephen_leake@stephe-leake.org> wrote in message
> news:854ni9c319.fsf@stephe-leake.org...
>> "Randy Brukardt" <randy@rrsoftware.com> writes:
> ...
>>Note the 'otherwise'; that's means the value is R.C'Address - R'Address
>>only if position is _not_ specified in a rep clause.
>
> Right, because if it is specified you use that value. But it *always* means
> R.C'Address - R'Address, whether it is specified or not; it's only that the
> *value* comes from the specification if there is one. So I take it you are
> complaining about a misplaced "otherwise".
Yes.
> I'd suggest you write up an Ada-Comment so it gets onto the agenda of the
> ARG to fix next time. (I personally think it is obvious, so I wouldn't worry
> about it, but people differ.)
I'll do that, but I agree it's not a big deal, since R.C'Address -
R'Address is the only reasonable meaning.
>> Do you think Cohen's paper makes it clear? I gather not. Why not?
>
> I read that paper three or four times and never understood any of it.
I'll have to read it again; its been a while.
> The discussion of "machine scalars" in the AI and in the RM (and
> especially during the ARG meetings) makes more sense to me than
> anything in Cohen's paper -- and in all honesty, that isn't intuitive,
> either.
>
> In any case, the Cohen paper is far too long to be used as part of the RM,
> and it surely defies condensation into a few easily understandable
> paragraphs. (If someone can do that, I'd welcome adding it to the AARM, I
> surely couldn't and I tried.)
I'm thinking it would be sufficient to say something like:
'position' specifies R.C'Address - R'Address (in units of Storage_Unit)
If the nondefault bit order applies, each 'position' must specify the start
of the machine scalar following the machine scalar used in the previous
component.
But I'll work on it more. A couple of examples would help. And we need
to point out that this does not affect byte endianness.
--
-- Stephe
next prev parent reply other threads:[~2013-01-23 1:38 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-22 3:21 GNAT 4.4.5 Record Bit_Order Endian issues Stephen Leake
2013-01-22 5:14 ` Jeffrey Carter
2013-01-23 1:29 ` Stephen Leake
2013-01-22 22:40 ` Randy Brukardt
2013-01-23 1:38 ` Stephen Leake [this message]
2013-01-23 10:58 ` Simon Wright
-- strict thread matches above, loose matches on Subject: below --
2013-01-14 17:43 awdorrin
2013-01-15 0:38 ` Randy Brukardt
2013-01-15 1:57 ` Adam Beneschan
2013-01-15 16:57 ` AdaMagica
2013-01-15 22:24 ` Stephen Leake
2013-01-16 10:44 ` Simon Wright
2013-01-16 19:00 ` AdaMagica
2013-01-16 21:34 ` Simon Wright
2013-01-16 23:14 ` Randy Brukardt
2013-01-17 3:49 ` Stephen Leake
2013-01-17 15:32 ` awdorrin
2013-01-18 9:49 ` Stephen Leake
2013-01-18 13:04 ` Robert A Duff
2013-01-19 1:43 ` Stephen Leake
2013-01-19 12:48 ` AdaMagica
2013-01-22 0:14 ` Randy Brukardt
2013-01-17 17:28 ` Simon Wright
2013-01-18 9:56 ` Stephen Leake
2013-01-17 18:04 ` awdorrin
2013-01-17 19:50 ` awdorrin
2013-01-18 9:58 ` Stephen Leake
2013-01-17 20:58 ` Simon Wright
2013-01-17 21:29 ` awdorrin
2013-01-17 22:16 ` awdorrin
2013-01-18 6:15 ` J-P. Rosen
2013-01-18 15:28 ` Niklas Holsti
2013-01-18 9:37 ` Stephen Leake
2013-01-18 12:24 ` awdorrin
2013-01-18 15:11 ` awdorrin
2013-01-19 1:48 ` Stephen Leake
2013-01-18 17:19 ` Simon Wright
2013-01-22 9:49 ` quinot
2013-01-28 13:39 ` quinot
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