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NNTP-Posting-Date: Mon, 09 Jul 2007 01:09:43 -0500
From: tmoran@acm.org
Newsgroups: comp.lang.ada
Subject: Re: sub-optimal code for packed boolean arrays -- bug or inherent
 limitation
References: <wccodim33u0.fsf@shell01.TheWorld.com>
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Date: 2007-07-09T01:09:43-05:00
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> Well, sort of.  Pack means to minimize storage even at the (possible)
> expense of speed of accessing the components.  Speed overall can be
> improved by packing.  For example, speed of copying and comparing the
> ...
> Measurement is a Good Thing.
  In my benchmark runs, the
        B(I) := not B(I);
and
        B(I) := B(I) xor True;
versions went from 10 down to 7 nanoseconds when I removed the pragma
pack, but the version with
        One(i) := True;
        B   := B xor One;
went from 5 to 700 nanoseconds.