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From: <tomas@tuxteam.de>
To: help-gnu-emacs@gnu.org
Subject: Re: Bit shift oddity?
Date: Mon, 19 Oct 2020 11:01:59 +0200	[thread overview]
Message-ID: <20201019090159.GA11667@tuxteam.de> (raw)
In-Reply-To: <3b4def4b-28c5-d549-0645-0056f0709549@gmail.com>

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On Mon, Oct 19, 2020 at 03:48:01AM -0400, Douglas Lewan wrote:
> Thanks. I see the same behavior with (ash).

Well, it's not exactly the "same behaviour", the inequalities
seem to be the same, but the intermediate numbers are not.

FWIW:

  (dotimes (i 10)
    (let ((shift (- -1 i)))
      (insert (format "shift=%d res=%d\n"
                      shift
                      (ash shift (lognot 0))))))
  =>

  shift=-1 res=-1
  shift=-2 res=-1
  shift=-3 res=-2
  shift=-4 res=-2
  shift=-5 res=-3
  shift=-6 res=-3
  shift=-7 res=-4
  shift=-8 res=-4
  shift=-9 res=-5
  shift=-10 res=-5
  
I don't quite understand the result; I may look into it later.

Cheers
 - t

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  reply	other threads:[~2020-10-19  9:01 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-19  0:19 Bit shift oddity? Douglas Lewan
2020-10-19  7:06 ` tomas
2020-10-19  7:48   ` Douglas Lewan
2020-10-19  9:01     ` tomas [this message]
2020-10-19 15:14       ` Stefan Monnier
2020-10-19 15:30         ` tomas
2020-10-19  9:23 ` Gregory Heytings via Users list for the GNU Emacs text editor
2020-10-19 15:19   ` Douglas Lewan

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