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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: AI12-0218: What is the portable representation clause for
 processing IETF packets on little-endian machines?
Date: Fri, 11 May 2018 12:40:16 +0300
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:52259
Date: 2018-05-11T12:40:16+03:00
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On 18-05-11 01:50 , Randy Brukardt wrote:

> Portable representation clauses are a waste of time, especially as machines
> are inconsistent in the ways that they number bits. Just don't go there.
> (218 solves one such problem, but there are many others.)

The ability to specify Bit_Order for record representations is very 
useful to me, as it allows my programs to be executed both on the target 
HW (big-endian SPARC) and on the development workstations (little-endian 
x86) with exactly the same HW-level input and output.

So thank you, ARG, for this!

There are some gotchas and limitations (most severe is the inability to 
specify the ordering of the components of packed arrays within records) 
but on the whole it works.

My current project has 115 cases of "for ...'Bit_Order use ...".

(And about three cases of having to manually expand packed arrays into 
individual record components because of the inability mentioned above.)

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .