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=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: 103376,9dec3ff1604723d9
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news1.google.com!news2.google.com!proxad.net!newsfeed.stueberl.de!newsr1.ipcore.viaginterkom.de!news-peer1!btnet-feed5!btnet!news.btopenworld.com!not-for-mail
From: "Martin Dowie" <martin.dowie@btopenworld.com>
Newsgroups: comp.lang.ada
Subject: Re: Bitmanipulation in Ada
Date: Wed, 18 Aug 2004 21:53:44 +0000 (UTC)
Organization: BT Openworld
Message-ID: <cg0j57$bal$1@sparta.btinternet.com>
References: <Xns9549E5E9CFFB1BerndSpechgmxcom@151.189.20.10>
NNTP-Posting-Host: host81-154-190-170.range81-154.btcentralplus.com
X-Trace: sparta.btinternet.com 1092866024 11605 81.154.190.170 (18 Aug 2004
 21:53:44 GMT)
X-Complaints-To: news-complaints@lists.btinternet.com
NNTP-Posting-Date: Wed, 18 Aug 2004 21:53:44 +0000 (UTC)
X-Newsreader: Microsoft Outlook Express 6.00.2800.1437
X-MSMail-Priority: Normal
X-Priority: 3
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441
Xref: g2news1.google.com comp.lang.ada:2819
Date: 2004-08-18T21:53:44+00:00
List-Id: <comp.lang.ada>

Bernd Specht wrote:
> 2. I did not found shift and rotate operations. Did I miss something
> or are there really none?

Check out package "Interfaces" they are all there - as are some common
predefined types.

> 3. When I want treat a value both as an integer and as a boolean
> array, how can i do this? In pascal I would use a tagless record like

Assuming you had a _really_ good reason to need to think of the data in both
terms, you have a number of options:

1) Unchecked_Conversion;

procedure Foo (Y : Unsigned_8) is
   procedure To_Array_8 is
      new Ada.Unchecked_Conversion (Unsigned_8, Array_8);
   X : Array_8 := To_Array_8 (Y);
begin
...

2) Address clause to 'overlay' 2 variables at the same address;

procedure Foo (Y : Unsigned_8) is
   X : Array_8;
   for X'Address use Y'Address;
begin
...

3) Variant record with a representation clause;

type Variant (Is_Array : Boolean := False) is
record
   case Is_Array is
      when False =>
         U : Unsigned_8;
      when True =>
         A : Array_8;
   end case;
end record;
for Variant use
record
   U at 0 range 0 .. 7;
   A at 0 range 0 .. 7;
end record;

This will leave it to the compiler where to put "Is_Array"

There are pros and cons to each - I'd rather use Ada.Unchecked_Conversion to
make it explicit that I'm switching representations.

Cheers

-- Martin