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309 lines
9.6 KiB
EmacsLisp
309 lines
9.6 KiB
EmacsLisp
;;; utf-8.el --- Limited UTF-8 decoding/encoding support
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;; Copyright (C) 2001 Electrotechnical Laboratory, JAPAN.
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;; Licensed to the Free Software Foundation.
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;; Keywords: multilingual, Unicode, UTF-8, i18n
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;; The coding-system `mule-utf-8' supports encoding/decoding of the
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;; following character sets to and from UTF-8:
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;;
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;; ascii
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;; eight-bit-control
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;; latin-iso8859-1
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;; mule-unicode-0100-24ff
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;; mule-unicode-2500-33ff
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;; mule-unicode-e000-ffff
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;;
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;; Characters of other character sets cannot be encoded with
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;; mule-utf-8. Note that the mule-unicode charsets currently lack
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;; case and syntax information, so things like `downcase' will only
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;; work for characters from ASCII and Latin-1.
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;;
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;; On decoding, Unicode characters that do not fit into the above
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;; character sets are handled as `eight-bit-control' or
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;; `eight-bit-graphic' characters to retain the information about the
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;; original byte sequence.
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;; UTF-8 is defined in RFC 2279. A sketch of the encoding is:
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;; scalar | utf-8
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;; value | 1st byte | 2nd byte | 3rd byte
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;; --------------------+-----------+-----------+----------
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;; 0000 0000 0xxx xxxx | 0xxx xxxx | |
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;; 0000 0yyy yyxx xxxx | 110y yyyy | 10xx xxxx |
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;; zzzz yyyy yyxx xxxx | 1110 zzzz | 10yy yyyy | 10xx xxxx
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;;; Code:
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(define-ccl-program ccl-decode-mule-utf-8
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;;
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;; charset | bytes in utf-8 | bytes in emacs
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;; -----------------------+----------------+---------------
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;; ascii | 1 | 1
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;; -----------------------+----------------+---------------
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;; eight-bit-control | 2 | 2
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;; latin-iso8859-1 | 2 | 2
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;; -----------------------+----------------+---------------
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;; mule-unicode-0100-24ff | 2 | 4
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;; (< 0800) | |
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;; -----------------------+----------------+---------------
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;; mule-unicode-0100-24ff | 3 | 4
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;; (>= 8000) | |
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;; mule-unicode-2500-33ff | 3 | 4
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;; mule-unicode-e000-ffff | 3 | 4
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;;
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;; Thus magnification factor is two.
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;;
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`(2
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((loop
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(read r0)
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;; 1byte encoding, i.e., ascii
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(if (r0 < #x80)
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(write r0)
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;; 2byte encoding
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(if (r0 < #xe0)
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((read r1)
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(r0 &= #x1f)
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(r0 <<= 6)
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(r1 &= #x3f)
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(r1 += r0)
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;; now r1 holds scalar value
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;; eight-bit-control
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(if (r1 < 160)
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((r0 = ,(charset-id 'eight-bit-control))
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(write-multibyte-character r0 r1))
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;; latin-iso8859-1
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(if (r1 < 256)
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((r0 = ,(charset-id 'latin-iso8859-1))
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(r1 -= 128)
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(write-multibyte-character r0 r1))
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;; mule-unicode-0100-24ff (< 0800)
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((r0 = ,(charset-id 'mule-unicode-0100-24ff))
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(r1 -= #x0100)
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(r2 = (((r1 / 96) + 32) << 7))
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(r1 %= 96)
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(r1 += (r2 + 32))
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(write-multibyte-character r0 r1)))))
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;; 3byte encoding
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(if (r0 < #xf0)
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((read r1 r2)
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(r3 = ((r0 & #x0f) << 12))
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(r3 += ((r1 & #x3f) << 6))
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(r3 += (r2 & #x3f))
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;; now r3 holds scalar value
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;; mule-unicode-0100-24ff (>= 0800)
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(if (r3 < #x2500)
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((r0 = ,(charset-id 'mule-unicode-0100-24ff))
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(r3 -= #x0100)
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(r3 //= 96)
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(r1 = (r7 + 32))
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(r1 += ((r3 + 32) << 7))
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(write-multibyte-character r0 r1))
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;; mule-unicode-2500-33ff
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(if (r3 < #x3400)
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((r0 = ,(charset-id 'mule-unicode-2500-33ff))
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(r3 -= #x2500)
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(r3 //= 96)
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(r1 = (r7 + 32))
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(r1 += ((r3 + 32) << 7))
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(write-multibyte-character r0 r1))
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;; U+3400 .. U+DFFF
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;; keep those bytes as eight-bit-{control|graphic}
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(if (r3 < #xe000)
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(;; #xe0 <= r0 < #xf0, so r0 is eight-bit-graphic
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(r3 = ,(charset-id 'eight-bit-graphic))
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(write-multibyte-character r3 r0)
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(if (r1 < #xa0)
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(r3 = ,(charset-id 'eight-bit-control)))
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(write-multibyte-character r3 r1)
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(if (r2 < #xa0)
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(r3 = ,(charset-id 'eight-bit-control))
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(r3 = ,(charset-id 'eight-bit-graphic)))
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(write-multibyte-character r3 r2))
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;; mule-unicode-e000-ffff
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((r0 = ,(charset-id 'mule-unicode-e000-ffff))
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(r3 -= #xe000)
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(r3 //= 96)
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(r1 = (r7 + 32))
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(r1 += ((r3 + 32) << 7))
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(write-multibyte-character r0 r1))))))
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;; 4byte encoding
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;; keep those bytes as eight-bit-{control|graphic}
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((read r1 r2 r3)
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;; r0 > #xf0, thus eight-bit-graphic
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(r4 = ,(charset-id 'eight-bit-graphic))
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(write-multibyte-character r4 r0)
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(if (r1 < #xa0)
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(r4 = ,(charset-id 'eight-bit-control)))
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(write-multibyte-character r4 r1)
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(if (r2 < #xa0)
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(r4 = ,(charset-id 'eight-bit-control))
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(r4 = ,(charset-id 'eight-bit-graphic)))
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(write-multibyte-character r4 r2)
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(if (r3 < #xa0)
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(r4 = ,(charset-id 'eight-bit-control))
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(r4 = ,(charset-id 'eight-bit-graphic)))
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(write-multibyte-character r4 r3)))))
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(repeat))))
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"CCL program to decode UTF-8.
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Basic decoding is done into the charsets ascii, latin-iso8859-1 and
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mule-unicode-*. Encodings of un-representable Unicode characters are
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decoded asis into eight-bit-control and eight-bit-graphic
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characters.")
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(define-ccl-program ccl-encode-mule-utf-8
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`(1
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(loop
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(read-multibyte-character r0 r1)
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(if (r0 == ,(charset-id 'ascii))
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(write r1)
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(if (r0 == ,(charset-id 'latin-iso8859-1))
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;; r1 scalar utf-8
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;; 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
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;; 20 0000 0000 1010 0000 1100 0010 1010 0000
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;; 7f 0000 0000 1111 1111 1100 0011 1011 1111
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((r0 = (((r1 & #x40) >> 6) | #xc2))
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(r1 &= #x3f)
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(r1 |= #x80)
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(write r0 r1))
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(if (r0 == ,(charset-id 'mule-unicode-0100-24ff))
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((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
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;; #x3f80 == (0011 1111 1000 0000)b
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(r1 &= #x7f)
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(r1 += (r0 + 224)) ; 240 == -32 + #x0100
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;; now r1 holds scalar value
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(if (r1 < #x0800)
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;; 2byte encoding
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((r0 = (((r1 & #x07c0) >> 6) | #xc0))
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;; #x07c0 == (0000 0111 1100 0000)b
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(r1 &= #x3f)
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(r1 |= #x80)
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(write r0 r1))
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;; 3byte encoding
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((r0 = (((r1 & #xf000) >> 12) | #xe0))
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(r2 = ((r1 & #x3f) | #x80))
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(r1 &= #x0fc0)
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(r1 >>= 6)
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(r1 |= #x80)
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(write r0 r1 r2))))
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(if (r0 == ,(charset-id 'mule-unicode-2500-33ff))
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((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
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(r1 &= #x7f)
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(r1 += (r0 + 9440)) ; 9440 == -32 + #x2500
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(r0 = (((r1 & #xf000) >> 12) | #xe0))
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(r2 = ((r1 & #x3f) | #x80))
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(r1 &= #x0fc0)
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(r1 >>= 6)
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(r1 |= #x80)
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(write r0 r1 r2))
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(if (r0 == ,(charset-id 'mule-unicode-e000-ffff))
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((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
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(r1 &= #x7f)
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(r1 += (r0 + 57312)) ; 57312 == -160 + #xe000
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(r0 = (((r1 & #xf000) >> 12) | #xe0))
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(r2 = ((r1 & #x3f) | #x80))
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(r1 &= #x0fc0)
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(r1 >>= 6)
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(r1 |= #x80)
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(write r0 r1 r2))
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(if (r0 == ,(charset-id 'eight-bit-control))
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;; r1 scalar utf-8
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;; 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
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;; 80 0000 0000 1000 0000 1100 0010 1000 0000
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;; 9f 0000 0000 1001 1111 1100 0010 1001 1111
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(write r1)
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(if (r0 == ,(charset-id 'eight-bit-graphic))
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;; r1 scalar utf-8
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;; 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
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;; a0 0000 0000 1010 0000 1100 0010 1010 0000
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;; ff 0000 0000 1111 1111 1101 1111 1011 1111
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(write r1)
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;; Unsupported character.
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;; Output U+FFFD, which is `ef bf bd' in UTF-8.
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((write #xef)
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(write #xbf)
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(write #xbd)))))))))
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(repeat)))
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"CCL program to encode into UTF-8.
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Only characters from the charsets ascii, eight-bit-control,
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eight-bit-graphic, latin-iso8859-1 and mule-unicode-* are recognized.
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Others are encoded as U+FFFD.")
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(make-coding-system
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'mule-utf-8 4 ?u
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"UTF-8 encoding for Emacs-supported Unicode characters.
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The supported Emacs character sets are:
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ascii
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eight-bit-control
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eight-bit-graphic
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latin-iso8859-1
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mule-unicode-0100-24ff
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mule-unicode-2500-33ff
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mule-unicode-e000-ffff
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Unicode characters out of the ranges U+0000-U+33FF and U+E200-U+FFFF
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are decoded into sequences of eight-bit-control and eight-bit-graphic
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characters to preserve their byte sequences. Emacs characters out of
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these ranges are encoded into U+FFFD.
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Note that, currently, characters in the mule-unicode charsets have no
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syntax and case information. Thus, for instance, upper- and
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lower-casing commands won't work with them."
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'(ccl-decode-mule-utf-8 . ccl-encode-mule-utf-8)
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'((safe-charsets
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ascii
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eight-bit-control
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eight-bit-graphic
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latin-iso8859-1
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mule-unicode-0100-24ff
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mule-unicode-2500-33ff
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mule-unicode-e000-ffff)
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(mime-charset . utf-8)
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(coding-category . coding-category-utf-8)
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(valid-codes (0 . 255))))
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(define-coding-system-alias 'utf-8 'mule-utf-8)
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