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From: =?utf-8?Q?Yannick_Duch=C3=AAne_=28Hibou57?=
 =?utf-8?Q?=29?=
 <yannick_duchene@yahoo.fr>
Newsgroups: comp.lang.ada
Subject: Re: bit numbers in packed arrays of Boolean
Date: Tue, 31 Aug 2010 13:34:00 +0200
Organization: Ada @ Home
Message-ID: <op.viavqyjmule2fv@garhos>
References: <82r5hfghjr.fsf@stephe-leake.org>
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Date: 2010-08-31T13:34:00+02:00
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Le Tue, 31 Aug 2010 13:14:48 +0200, Stephen Leake  =

<stephen_leake@stephe-leake.org> a =C3=A9crit:
> LRM 13.9(5) says Bit_Array_16_Type and Unsigned_16 have the same
> representation, but it does not specifically address the index order.
At least ARM 3.6 Array Types does not states anything. But as you used  =

Unchecked_Conversion, it is unlikely to be portable or this result could=
  =

be enforced. Let say this is the result of a compiler with descent defau=
lt  =

behaviors.

ARM 13.9 Unchecked Type Conversions says:

    11.a/2  Implementation defined: The effect of unchecked conversion f=
or
    instances with nonscalar result types whose effect is not defined by=

    the language.

And do not believe the reference defines anything for an array of 16  =

bit-layout booleans.

Possibly depends on how the index is interpreted: as an index in the  =

polynomial representation of the word value or as a bit index ? Both wou=
ld  =

be legitimate for a compiler.

That was my humble opinion on the topic.


-- =

=E2=80=9CDual licensing is the Perl's way to disinfect the GNU General P=
ublic  =

Virus!=E2=80=9D (anonymous)