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From: storm@cua.dk (Kim F. Storm)
Cc: emacs-devel@gnu.org
Subject: Re: struct.el -- a package to encode/decode binary data
Date: 21 Mar 2002 16:36:42 +0100	[thread overview]
Message-ID: <5x663qgcfp.fsf@kfs2.cua.dk> (raw)
In-Reply-To: <Pine.SUN.3.91.1020321164353.11007C-100000@is>

Eli Zaretskii <eliz@is.elta.co.il> writes:

> On 21 Mar 2002, Kim F. Storm wrote:
> 
> > > > Is there some specific reason not to use unibyte strings here?
> > > 
> > > They are simply not needed here (AFAICS). 
> > 
> > On the surface, it looks "obvious" to use unibyte strings for
> > data which is known to be - and processed as - byte-oriented
> > data.
> 
> That's the C programmer in you trying to get free ;-)

Right on the spot :-)

> > Am I right in assuming that aref, aset, and substring are potentially
> > much slower on a multibyte string than on a unibyte string?

I just tried to measure whether there is any difference, by copying
between two strings like this:
  (let ((i (length a)))
    (while (> i 0)
      (setq i (1- i))
      (aset a i (aref b i))))

a and b are either both multibyte or both unibyte and initialized
to all NULs.  The difference in time is very small if there is any...

> 
> If the string holds non-ASCII text, yes.  But not in your case, where the 
> ``string'' holds binary data, I think.

.. which confirms your belief.

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk


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  reply	other threads:[~2002-03-21 15:36 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <Pine.SUN.3.91.1020319133840.17982G-100000@is>
2002-03-19 14:34 ` struct.el -- a package to encode/decode binary data Kim F. Storm
2002-03-19 21:27   ` Thien-Thi Nguyen
2002-03-21  9:04   ` Richard Stallman
2002-03-21 11:15     ` Eli Zaretskii
2002-03-21 13:31       ` Kim F. Storm
2002-03-21 14:56         ` Eli Zaretskii
2002-03-21 15:36           ` Kim F. Storm [this message]
2002-03-21 16:58             ` Stefan Monnier
2002-03-21 19:45               ` Eli Zaretskii
2002-03-22  1:05                 ` Stefan Monnier
2002-03-22 11:04                   ` Eli Zaretskii
2002-03-22  0:37           ` Miles Bader
2002-03-23  2:35           ` Richard Stallman
2002-03-21 16:53         ` Stefan Monnier
2002-03-23  2:36       ` Richard Stallman
2002-03-22  1:30 Kenichi Handa
  -- strict thread matches above, loose matches on Subject: below --
2002-03-22  1:25 Kenichi Handa
2002-03-22  1:27 ` Stefan Monnier
2002-03-18 23:12 Kim F. Storm
2002-03-19  0:25 ` Miles Bader
2002-03-19  7:02 ` Eli Zaretskii
2002-03-19 12:34   ` Stefan Monnier
2002-03-19 14:38     ` Eli Zaretskii
2002-03-19 14:33 ` Luke Gorrie

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