Re: kernel tty patches

[Ienup Sung <ienup.sung@xxxxxxxxxxx>]

The wcwidth(3C) of POSIX requires to return, in general sense, four
distingtive values, 0, 1, 2, and -1. (The return value 0 have to be
overloaded for zero-width characters and for a case if input argument is
a NULL wide character code in this case.) Hence we need only two bits per
each character. Which means for a plane, you will need 2 x 65536 bits
and that is 16KB for a plane if you want to have a faster algorithm for
width calculation and thus want to have the width values available for
all Unicode characters in the plane. This will require that the kernel will
eventually need to have 16KB x 17 planes = 272KB to represent all possible
Unicode characters. As a starter, though, we will only need 16KB x 3 = 48KB
of memory space if we count only BMP, SMP, and SIP planes.

Further compaction of memory space is possible if necessary of course.

With regards,

Ienup


] Date: Wed, 24 Jan 2001 16:55:12 +0000 (GMT)
] From: Robert Brady <robert@xxxxxxxxxx>
] Subject: Re: kernel tty patches
] X-Sender: robert@xxxxxxxxxxx
] To: linux-utf8@xxxxxxxxxxxxxxxxxxxx
] MIME-version: 1.0
] 
] On Wed, 24 Jan 2001 Andries.Brouwer@xxxxxx wrote:
] 
] > >> Is this in kernel 2.4 now?
] > 
] > > No. There doesn't appear to be consensus that the tty built-in line
] > > editor must support multibyte encodings.
] > 
] > My opinion is slightly different: it must, but this is a very
] > low-priority item. It will, eventually, I think.
] 
] Even if this entails having a wcwidth() table in-kernel?
] 
] -- 
] Robert Brady
] robert@xxxxxxxxxx
] 
] -
] Linux-UTF8:   i18n of Linux on all levels
] Archive:      http://mail.nl.linux.org/lists/
-
Linux-UTF8:   i18n of Linux on all levels
Archive:      http://mail.nl.linux.org/lists/