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From: Stephen Leake <Stephen.A.Leake@nasa.gov>
Newsgroups: comp.lang.ada
Subject: Re: Endianness independance
Date: 05 Mar 2003 12:37:13 -0500
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Jeffrey Carter <jrcarter@acm.org> writes:

> Stephen Leake wrote:
> > Jeffrey Carter <jrcarter@acm.org> writes:
> >
> >>You can make this system independent by using
> >>System.Default_Bit_Order, which, thanks to an AI (I don't remember
> >>which, but you can look it up) is static.
> > What do you mean by "system independent"? This code is already
> > portable without change across targets that differ in endianness;
> > that's whay I mean by "system independent".
> > Exactly how would I use System.Default_Bit_Order for this purpose?
> > I can check that System.Default_Bit_Order has a particular value, and
> > only provide a rep clause that is correct for that value. But I don't
> > see how to use System.Default_Bit_Order in the rep clause; it does not
> > provide enough information.
> 
> You said your package was "system dependent" because you have to
> change it for different platforms. 

Hmm. Maybe you mean the SAL.Endianness package (I posted two packages;
SAL.Endianness and Foo - please be specific!). Yes, that has to be
different for different platforms. But, you only have to write it once
for each platform, and I already have. So I don't have to edit code
when I change platforms; I just have to change which code is included
in the compilation.

> Using Default_Bit_Order you can make it work without change on all
> platforms. You can use 'Pos of Default_Bit_Order to calculate all of
> the named numbers in your package. You can then continue to use your
> package as before, but without changing it when you change
> platforms.

Well, maybe. I'm comfortable with the package as it is. If you'd like
to contribute, feel free to post your version :).

-- 
-- Stephe