From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!gandalf.srv.welterde.de!news.jacob-sparre.dk!franka.jacob-sparre.dk!pnx.dk!.POSTED.rrsoftware.com!not-for-mail
From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: AI12-0218: What is the portable representation clause for
 processing IETF packets on little-endian machines?
Date: Thu, 10 May 2018 17:50:08 -0500
Organization: JSA Research & Innovation
Message-ID: <pd2ib3$emk$1@franka.jacob-sparre.dk>
References: <ec0145a4-9698-41f2-bc70-964dc1850e50@googlegroups.com>
 <pd26sb$ik6$1@gioia.aioe.org>
 <2821b8e0-2c64-4621-b65e-337027fc121e@googlegroups.com>
Injection-Date: Thu, 10 May 2018 22:50:11 -0000 (UTC)
Injection-Info: franka.jacob-sparre.dk;
 posting-host="rrsoftware.com:24.196.82.226";
	logging-data="15060"; mail-complaints-to="news@jacob-sparre.dk"
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2900.5931
X-RFC2646: Format=Flowed; Original
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.7246
Xref: reader02.eternal-september.org comp.lang.ada:52225
Date: 2018-05-10T17:50:08-05:00
List-Id: <comp.lang.ada>

"Dan'l Miller" <optikos@verizon.net> wrote in message 
news:2821b8e0-2c64-4621-b65e-337027fc121e@googlegroups.com...

>But until then, we're not tilting at windmills; we live in IETF's reality 
>of their
>packet-header formats.  Now show how to process them portably in Ada
>without AI12-0218.

Why would you want to process them portably? Low-level hardware specific 
code (and socket drivers are always that) is never portable (too much 
hardware dependence); the usual Ada plan is to carefully encapsulate such 
stuff in a package and provide several bodies for different targets. Code 
using such a package is portable of course (any differences are filed-off by 
the package).

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.)

                     Randy.