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From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
Subject: highest bit, statically determined
Date: Sat, 29 Sep 2012 19:34:09 +0200
Date: 2012-09-29T19:34:09+02:00	[thread overview]
Message-ID: <50673111$0$9505$9b4e6d93@newsspool1.arcor-online.net> (raw)

Is there a shorter/better way of having the compiler
find the highest bit = 1 in a static numeric constant?

If N is such a constant, e.g. Some_Type'Last where
Some_Type'Size = 8 and its bound are static, then

    Highest_Bit_In_Octet : constant :=
      Natural'Max
      (8 * Boolean'Pos (N / 2**7 > 0),
       Natural'Max
       (7 * Boolean'Pos (N / 2**6 > 0),
        Natural'Max
        (6 * Boolean'Pos (N / 2**5 > 0),
         Natural'Max
         (5 * Boolean'Pos (N / 2**4 > 0),
          Natural'Max
          (4 * Boolean'Pos (N / 2**3 > 0),
           Natural'Max
           (3 * Boolean'Pos (N / 2**2 > 0),
            Natural'Max
            (2 * Boolean'Pos (N / 2**1 > 0),
             Natural'Max
             (1 * Boolean'Pos (N / 2**0 > 0), 0))))))));



             reply	other threads:[~2012-09-29 17:34 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-09-29 17:34 Georg Bauhaus [this message]
2012-09-29 18:11 ` highest bit, statically determined Pascal Obry
2012-09-29 18:59   ` Georg Bauhaus
2012-09-29 19:18     ` Georg Bauhaus
2012-09-29 18:57 ` Bill Findlay
2012-09-29 19:16   ` Bill Findlay
2012-09-29 21:36     ` Georg Bauhaus
2012-09-29 22:06       ` Georg Bauhaus
2012-09-29 23:38       ` Bill Findlay
2012-09-30 15:01       ` Vadim Godunko
2012-11-04 20:45     ` Yannick Duchêne (Hibou57)
2012-11-04 22:00       ` Bill Findlay
2012-09-30 15:39 ` Anatoly Chernyshev
2012-09-30 18:36   ` Shark8
2012-10-01  8:07   ` Georg Bauhaus
2012-10-01  8:11     ` Georg Bauhaus
2012-10-01  8:52     ` Anatoly Chernyshev
2012-10-01 21:30       ` Georg Bauhaus
2012-10-01 22:55         ` Shark8
2012-10-01 23:25           ` Georg Bauhaus
2012-10-02 11:03         ` Brian Drummond
2012-10-03  9:30           ` kalvink65
2012-10-03 18:54             ` Georg Bauhaus
2012-10-04  7:46               ` Georg Bauhaus
2012-10-04  8:25           ` Stephen Leake
2012-10-04 10:01       ` kalvin.news
2012-10-05  7:50         ` Anatoly Chernyshev
2012-10-05  8:38           ` Anatoly Chernyshev

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