Re: [PATCH] keyboard driver improvement for Unicode mode

H. Peter Anvin (hpa@transmeta.com)
8 Aug 1999 21:53:11 GMT

Followup to: <199908081529.RAA28199@jaures.ilog.fr>
By author: Bruno Haible <haible@ilog.fr>
In newsgroup: linux.dev.kernel
>
> 3. It permits Unicode keymaps to access the U+f800..U+ffff Unicode range
> which was previously inaccessible due to the way keysyms are
> represented in the kernel.
>

Hi there,

Thanks for working on this. However, it looks like you're still doing
magic stuff with U+E800-U+EFFF. That's a quite unfortunate choice,
since this is the user/application reserved character area, and hence
represents real characters.

Note that under Linux, there are two ranges you can use that are
guaranteed to not match any real characters:

U+F000 to U+F7FF:

This is the "straight-to-font" region for output; clearly it
is meaningless for input; perhaps it could be used for raw
scancodes or something like that, but there aren't any plans
for doing so.

U+D800 to U+DFFF:

This is the region reserved for UTF-16 surrogates. Since
UTF-16 doesn't apply to this context, they can be used under
the "subject to higher protocol" provision (in this case, the
higher protocol dictates that 0xd800 to 0xdfff aren't unicodes
at all, but rather escape sequences to the keyboard driver.)

-hpa

-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!


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