Re: adding a new encoding

[Kenichi Handa <handa@m17n.org>]

In article <20040621200633.GF1361@ata.cs.hun.edu.tr>, Baurjan Ismagulov <ibr@ata.cs.hun.edu.tr> writes:
> > > * Emacs uses ISO 2022 internally.
> > Not correct.  Emacs uses character codes of each ISO-2022
> > conforming charsets.

> And each character is prepended with a charset code?

Yes, prepended with a charset code of range 0x80..0x9D plus
optional extented charset code of range 0xA0..0xFF, and code
points (0x20..0x7F) are `logior'ed with 0x80.  So a
multibyte representation of character is classified into
these:
	0x00..0x7F
	0x80..0x9D 0xA0..0xFF
	0x80..0x9D 0xA0..0xFF 0xA0..0xFF
	0x80..0x9D 0xA0..0xFF 0xA0..0xFF 0xA0..0xFF

> How do raw bytes
> look like in Emacs memory for, say, \U+0410\U+00DF\U+0534? Is there an
> easy way to see that (princ somewhere in
> lisp/international/mule-cmds.el)?

Try this:

(string-as-unibyte (string (decode-char 'ucs #x0410)
			   (decode-char 'ucs #x00DF)
			   (decode-char 'ucs #x0534)))

M-x list-character-sets also give some information.

But, you'ld better not write a code depending on it.
Unicode-based Emacs (that will come after the release of
current CVS HEAD) uses UTF-8 as a multibyte representation.

---
Ken'ichi HANDA
handa@m17n.org