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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Ada 95 Numerics questions for the experts
Date: 1997/08/28
Message-ID: <dewar.872745692@merv>#1/1
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References: <3401C14B.480@gsfc.nasa.gov> <dewar.872560585@merv>
 <jcreem-2608970711210001@ljd155.sanders.lockheed.com> <dewar.872630607@merv>
 <jeffrey.m.creem-2708970802350001@ljd155.sanders.lockheed.com>
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 <jeffrey.m.creem-2708971721530001@ljd155.sanders.lockheed.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-08-28T00:00:00+00:00
List-Id: <comp.lang.ada>


<<Nope. The AdaMajic front end (Green hills in this case) rounds the
components to 8 bits even in the precense of a pragma pack
you get a 64 Byte array.>>

SOunds like a bug to me, since these compilers say they support
annex C, this means that the implementation advice in chapter 13 (13.2(9))

    9  For a packed array type, if the component subtype's Size is less
       than or equal to the word size, and Component_Size is not
       specified for the type, Component_Size should be less than or
       equal to the Size of the component subtype, rounded up to the
       nearest factor of the word size.

which of course becomes a requirement if you claim annex C support.

Reading this paragraph, we see that it is OK to round up to 4-bits,
but certainly not 8-bits.

As I noted before, GNAT does not round up at all, and packs tightly at
3 bits, letting components spill over byte and word boundaries. This
is not required by para 9, but is of course consistent with it ("less
than or equal").