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: 103376,553a6b79b2471571
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!postnews.google.com!p79g2000cwp.googlegroups.com!not-for-mail
From: "jimmaureenrogers@worldnet.att.net" <jimmaureenrogers@worldnet.att.net>
Newsgroups: comp.lang.ada
Subject: Re: How do you bitwise operations in Ada '83 and '95
Date: 18 Jul 2006 11:53:20 -0700
Organization: http://groups.google.com
Message-ID: <1153248800.834457.183940@p79g2000cwp.googlegroups.com>
References: <1153244316.853254.291560@m79g2000cwm.googlegroups.com>
NNTP-Posting-Host: 69.170.65.169
Mime-Version: 1.0
Content-Type: text/plain; charset="iso-8859-1"
X-Trace: posting.google.com 1153248804 7768 127.0.0.1 (18 Jul 2006 18:53:24
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: Tue, 18 Jul 2006 18:53:24 +0000 (UTC)
User-Agent: G2/0.2
X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US;
 rv:1.8.0.4) Gecko/20060508 Firefox/1.5.0.4,gzip(gfe),gzip(gfe)
Complaints-To: groups-abuse@google.com
Injection-Info: p79g2000cwp.googlegroups.com; posting-host=69.170.65.169;
   posting-account=SqOfxAwAAAAkL81YAPGH1JdBwpUXw9ZG
Xref: g2news2.google.com comp.lang.ada:5777
Date: 2006-07-18T11:53:20-07:00
List-Id: <comp.lang.ada>

Chris L wrote:
> Also, do you have small coding examples that demonstrate this?

Bitwise operations in Ada 83 are accomplished through packed
arrays of boolean. In Ada 95 you can also accomplish
bit-wise operations (and, or, xor) on modular types.

The following example shows bit-wise operations using a
packed array of boolean. The small program computes prime
number using a sieve of Erastosthenese. The array flagging
found values is implemented as a packed array of boolean.

Notice that individual bits are directly addressable as array
elements in a packed array of boolean.

with Ada.Command_Line;use Ada.Command_Line;
with Ada.Text_Io;use Ada.Text_Io;
with Ada.Integer_Text_Io;use Ada.Integer_Text_Io;

procedure Nsievebits is

   function Count (M : in     Natural ) return Natural is
      type Boolean_Array is array (2 .. M) of Boolean;
      pragma Pack (Boolean_Array);
      C : Natural       := 0;
      S : Boolean_Array := (others => True);
      I : Positive;
   begin
      for K in S'range loop
         if S(K) then
            C := C + 1;
            I := K;
            loop
               I := I + K;
               exit when I > M;
               S(I) := False;
            end loop;
         end if;
      end loop;
      return C;
   end Count;

   procedure Run (N : in     Natural ) is
      M : Natural;
   begin
      M := 2 ** N * 10_000;
      Put ("Primes up to ");
      Put (Item  => M, Width => 8);
      Put (Item  => Count (M), Width => 8);
      New_Line;
   end Run;

   N : constant Natural := Natural'Value (Argument (1));
begin
   Run (N);
   Run (N - 1);
   Run (N - 2);
end Nsievebits; 
   
Jim Rogers