From: "Eli Zaretskii" <eliz@is.elta.co.il>
Cc: storm@cua.dk, emacs-devel@gnu.org
Subject: Re: struct.el -- a package to encode/decode binary data
Date: Fri, 22 Mar 2002 13:04:11 +0200 [thread overview]
Message-ID: <2427-Fri22Mar2002130411+0200-eliz@is.elta.co.il> (raw)
In-Reply-To: <200203220105.g2M159I19881@rum.cs.yale.edu> (monnier+gnu/emacs@rum.cs.yale.edu)
> From: "Stefan Monnier" <monnier+gnu/emacs@rum.cs.yale.edu>
> Date: Thu, 21 Mar 2002 20:05:09 -0500
>
> > Most of them, those between 160 and 255 _are_ represented as a single
> > byte, even in a multibyte string/buffer. That's the eight-bit-graphic
> > character set.
>
> Interesting. It still means that binary values between 128 and 160
> (i.e. from eight-bit-control) are posing problems when calling `aset'.
Yes, that's true. So moving through a multibyte buffer/string with
binary data is slightly less efficient than with unibyte buffer/string
(assuming a uniform distribution of possible 8-bit values in the range
[0..255]). Moving *back* through such buffers/strings is especially
painful, since you cannot in advance find the head of the multibyte
sequence, which tells how many bytes to move to skip the character.
However, I think in code that constructs numbers from binary data you
don't normally need to move back, or use aset. You normally need to
move/scan forward a small number of bytes, while you accumulate their
values into a number. That should be reasonably efficient, and so
using unibyte strings doesn't seem to be justified.
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next prev parent reply other threads:[~2002-03-22 11:04 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
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 [this message]
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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