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From: dewarr@my-dejanews.com
Subject: Re: GNAT Opinions
Date: 1998/12/25
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 <75rvnq$h75@dfw-ixnews10.ix.netcom.com> <75tr9e$3h8$1@remarQ.com>
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Date: 1998-12-25T00:00:00+00:00
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In article <75tr9e$3h8$1@remarQ.com>,
  "Pat Rogers" <progers@NOclasswideSPAM.com> wrote:


> Since you mentioned it, endian-independent representation
> clauses
> can be written (although they are not easy to read, but
> then, they
> never require changes due to endianess).  Norm Cohen
> wrote about how
> to do it in Ada Letters.  I have a free package to
> support it, with
> a demo program, at my web site:

This approach solves only a limited part of the problem
that people would like to solve. There are many variations
of this problem that occur in actual practice,

Consider one of the most fundamental, which
is that you have an external data stream that produces a
big endian integer as four consecutive bytes in big-endian
order. There is no magic rep clause to cause a compiler on
a little-endian machine to acquire this data "correctly".
Indeed the difficulty may vary from machine to machine, on
some machines a quite long and tedious sequence of
instructions may be required to reassemble the data.

Robert Dewar
Ada Core Technologies

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