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From: lutz@iks-jena.de (Lutz Donnerhacke)
Newsgroups: comp.lang.ada
Subject: Re: Ada The Best Language?
Date: Fri, 20 Jul 2001 12:39:28 +0000 (UTC)
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* Bertrand Augereau wrote:
>"Lutz Donnerhacke" <lutz@iks-jena.de> a �crit dans le message news:
>> https://www.iks-jena.de/mitarb/lutz/ada/net/net-packet-ip-v4__ads.htm
>
>Ok, that's what I was thinking about but I had to be sure.
>In fact C++ bitfields allow you to pack information exactly (well almost
>exactly, you have to take care of the offset with appropriate padding, but
>bitfields take care of the 'range') this way in your ADT. This is almost
>equivalent.

Please specify the C++ Code for offset 6.
      [...]
      dont_fragment    at  6 range 6 .. 6;
      more_fragments   at  6 range 5 .. 5;
      offset1          at  6 range 0 .. 4;
      [...]

Ada95 still have problems, there is no portable way to specify the layout of
the whole 12bit offset.

>But I'm not sure of endianness consideration in both cases, especially for
>network code.

https://www.iks-jena.de/mitarb/lutz/ada/net/net-portability__adb.htm

It's horrible ugly, but compile time evaluable and the generated code is
incredibly fine. Ever seen a Compiler generating an endian prefix on alpha?