--- /dev/null
+;;; utf-8.el --- Limited UTF-8 decoding/encoding support
+
+;; Copyright (C) 2001 Electrotechnical Laboratory, JAPAN.
+;; Licensed to the Free Software Foundation.
+
+;; Keywords: multilingual, Unicode, UTF-8
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 2, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING. If not, write to the
+;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;; The coding-system `mule-utf-8' supports encoding/decoding of the
+;; following character sets:
+;;
+;; ascii
+;; eight-bit-control
+;; latin-iso8859-1
+;; mule-unicode-0100-24ff
+;; mule-unicode-2500-33ff
+;; mule-unicode-e000-ffff
+;;
+;; Characters of other character sets cannot be encoded with
+;; mule-utf-8.
+;;
+;; On decoding, Unicode characters that do not fit in above character
+;; sets are handled as `eight-bit-control' or `eight-bit-graphic'
+;; characters to retain original information (i.e. original byte
+;; sequence).
+
+;; scalar | utf-8
+;; value | 1st byte | 2nd byte | 3rd byte
+;; --------------------+-----------+-----------+----------
+;; 0000 0000 0xxx xxxx | 0xxx xxxx | |
+;; 0000 0yyy yyxx xxxx | 110y yyyy | 10xx xxxx |
+;; zzzz yyyy yyxx xxxx | 1110 zzzz | 10yy yyyy | 10xx xxxx
+
+;;; Code:
+
+(define-ccl-program ccl-decode-mule-utf-8
+ ;;
+ ;; charset | bytes in utf-8 | bytes in emacs
+ ;; -----------------------+----------------+---------------
+ ;; ascii | 1 | 1
+ ;; -----------------------+----------------+---------------
+ ;; eight-bit-control | 2 | 2
+ ;; latin-iso8859-1 | 2 | 2
+ ;; -----------------------+----------------+---------------
+ ;; mule-unicode-0100-24ff | 2 | 4
+ ;; (< 0800) | |
+ ;; -----------------------+----------------+---------------
+ ;; mule-unicode-0100-24ff | 3 | 4
+ ;; (>= 8000) | |
+ ;; mule-unicode-2500-33ff | 3 | 4
+ ;; mule-unicode-e000-ffff | 3 | 4
+ ;;
+ ;; Thus magnification factor is two.
+ ;;
+ `(2
+ ((loop
+ (read r0)
+
+ ;; 1byte encoding, i.e., ascii
+ (if (r0 < #x80)
+ (write r0)
+
+ ;; 2byte encoding
+ (if (r0 < #xe0)
+ ((read r1)
+ (r0 &= #x1f)
+ (r0 <<= 6)
+ (r1 &= #x3f)
+ (r1 += r0)
+ ;; now r1 holds scalar value
+
+ ;; eight-bit-control
+ (if (r1 < 160)
+ ((r0 = ,(charset-id 'eight-bit-control))
+ (write-multibyte-character r0 r1))
+
+ ;; latin-iso8859-1
+ (if (r1 < 256)
+ ((r0 = ,(charset-id 'latin-iso8859-1))
+ (r1 -= 128)
+ (write-multibyte-character r0 r1))
+
+ ;; mule-unicode-0100-24ff (< 0800)
+ ((r0 = ,(charset-id 'mule-unicode-0100-24ff))
+ (r1 -= #x0100)
+ (r2 = (((r1 / 96) + 32) << 7))
+ (r1 %= 96)
+ (r1 += (r2 + 32))
+ (write-multibyte-character r0 r1)))))
+
+ ;; 3byte encoding
+ (if (r0 < #xf0)
+ ((read r1 r2)
+ (r3 = ((r0 & #x0f) << 12))
+ (r3 += ((r1 & #x3f) << 6))
+ (r3 += (r2 & #x3f))
+ ;; now r3 holds scalar value
+
+ ;; mule-unicode-0100-24ff (>= 0800)
+ (if (r3 < #x2500)
+ ((r0 = ,(charset-id 'mule-unicode-0100-24ff))
+ (r3 -= #x0100)
+ (r3 //= 96)
+ (r1 = (r7 + 32))
+ (r1 += ((r3 + 32) << 7))
+ (write-multibyte-character r0 r1))
+
+ ;; mule-unicode-2500-33ff
+ (if (r3 < #x3400)
+ ((r0 = ,(charset-id 'mule-unicode-2500-33ff))
+ (r3 -= #x2500)
+ (r3 //= 96)
+ (r1 = (r7 + 32))
+ (r1 += ((r3 + 32) << 7))
+ (write-multibyte-character r0 r1))
+
+ ;; U+3400 .. U+DFFF
+ ;; keep those bytes as eight-bit-{control|graphic}
+ (if (r3 < #xe000)
+ (;; #xe0 < r0 < #xf0, so r0 is eight-bit-graphic
+ (r3 = ,(charset-id 'eight-bit-graphic))
+ (write-multibyte-character r3 r0)
+ (if (r1 < #xa0)
+ (r3 = ,(charset-id 'eight-bit-control)))
+ (write-multibyte-character r3 r1)
+ (if (r2 < #xa0)
+ (r3 = ,(charset-id 'eight-bit-control))
+ (r3 = ,(charset-id 'eight-bit-graphic)))
+ (write-multibyte-character r3 r2))
+
+ ;; mule-unicode-e000-ffff
+ ((r0 = ,(charset-id 'mule-unicode-e000-ffff))
+ (r3 -= #xe000)
+ (r3 //= 96)
+ (r1 = (r7 + 32))
+ (r1 += ((r3 + 32) << 7))
+ (write-multibyte-character r0 r1))))))
+
+ ;; 4byte encoding
+ ;; keep those bytes as eight-bit-{control|graphic}
+ ((read r1 r2 r3)
+ ;; r0 > #xf0, thus eight-bit-graphic
+ (r4 = ,(charset-id 'eight-bit-graphic))
+ (write-multibyte-character r4 r0)
+ (if (r1 < #xa0)
+ (r4 = ,(charset-id 'eight-bit-control)))
+ (write-multibyte-character r4 r1)
+ (if (r2 < #xa0)
+ (r4 = ,(charset-id 'eight-bit-control))
+ (r4 = ,(charset-id 'eight-bit-graphic)))
+ (write-multibyte-character r4 r2)
+ (if (r3 < #xa0)
+ (r4 = ,(charset-id 'eight-bit-control))
+ (r4 = ,(charset-id 'eight-bit-graphic)))
+ (write-multibyte-character r4 r3)))))
+
+ (repeat))))
+
+ "CCL program to decode UTF-8 into ascii, eight-bit-control, latin-iso8859-1 and mule-unicode-*.")
+
+(define-ccl-program ccl-encode-mule-utf-8
+ `(1
+ (loop
+ (read-multibyte-character r0 r1)
+
+ (if (r0 == ,(charset-id 'ascii))
+ (write r1)
+
+ (if (r0 == ,(charset-id 'latin-iso8859-1))
+ ;; r1 scalar utf-8
+ ;; 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
+ ;; 20 0000 0000 1010 0000 1100 0010 1010 0000
+ ;; 7f 0000 0000 1111 1111 1100 0011 1011 1111
+ ((r0 = (((r1 & #x40) >> 6) | #xc2))
+ (r1 &= #x3f)
+ (r1 |= #x80)
+ (write r0 r1))
+
+ (if (r0 == ,(charset-id 'mule-unicode-0100-24ff))
+ ((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
+ ;; #x3f80 == (0011 1111 1000 0000)b
+ (r1 &= #x7f)
+ (r1 += (r0 + 224)) ; 240 == -32 + #x0100
+ ;; now r1 holds scalar value
+ (if (r1 < #x0800)
+ ;; 2byte encoding
+ ((r0 = (((r1 & #x07c0) >> 6) | #xc0))
+ ;; #x07c0 == (0000 0111 1100 0000)b
+ (r1 &= #x3f)
+ (r1 |= #x80)
+ (write r0 r1))
+ ;; 3byte encoding
+ ((r0 = (((r1 & #xf000) >> 12) | #xe0))
+ (r2 = ((r1 & #x3f) | #x80))
+ (r1 &= #x0fc0)
+ (r1 >>= 6)
+ (r1 |= #x80)
+ (write r0 r1 r2))))
+
+ (if (r0 == ,(charset-id 'mule-unicode-2500-33ff))
+ ((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
+ (r1 &= #x7f)
+ (r1 += (r0 + 9440)) ; 9440 == -32 + #x2500
+ (r0 = (((r1 & #xf000) >> 12) | #xe0))
+ (r2 = ((r1 & #x3f) | #x80))
+ (r1 &= #x0fc0)
+ (r1 >>= 6)
+ (r1 |= #x80)
+ (write r0 r1 r2))
+
+ (if (r0 == ,(charset-id 'mule-unicode-e000-ffff))
+ ((r0 = ((((r1 & #x3f80) >> 7) - 32) * 96))
+ (r1 &= #x7f)
+ (r1 += (r0 + 57312)) ; 57312 == -160 + #xe000
+ (r0 = (((r1 & #xf000) >> 12) | #xe0))
+ (r2 = ((r1 & #x3f) | #x80))
+ (r1 &= #x0fc0)
+ (r1 >>= 6)
+ (r1 |= #x80)
+ (write r0 r1 r2))
+
+ (if (r0 == ,(charset-id 'eight-bit-control))
+ ;; r1 scalar utf-8
+ ;; 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
+ ;; 80 0000 0000 1000 0000 1100 0010 1000 0000
+ ;; 9f 0000 0000 1001 1111 1100 0010 1001 1111
+ (write r1)
+
+ (if (r0 == ,(charset-id 'eight-bit-graphic))
+ ;; r1 scalar utf-8
+ ;; 0000 0yyy yyxx xxxx 110y yyyy 10xx xxxx
+ ;; a0 0000 0000 1010 0000 1100 0010 1010 0000
+ ;; ff 0000 0000 1111 1111 1101 1111 1011 1111
+ (write r1)
+
+ ;; unsupported character.
+ ;; output U+FFFD, which is `ef bf bd' in UTF-8
+ ;; actually it never reach here
+ ((write #xef)
+ (write #xbf)
+ (write #xbd)))))))))
+ (repeat)))
+
+ "CCL program to encode ascii, eight-bit-control, latin-iso8859-1 and mule-unicode-*. into UTF-8.")
+
+(make-coding-system
+ 'mule-utf-8 4 ?u
+ "UTF-8 encoding for Emacs-supported Unicode characters.
+Supported character sets are:
+ ascii
+ eight-bit-control
+ eight-bit-graphic
+ latin-iso8859-1
+ mule-unicode-0100-24ff
+ mule-unicode-2500-33ff
+ mule-unicode-e000-ffff
+
+Unicode characters out of these ranges are decoded
+into eight-bit-control or eight-bit-graphic."
+
+ '(ccl-decode-mule-utf-8 . ccl-encode-mule-utf-8)
+ '((safe-charsets
+ ascii
+ eight-bit-control
+ eight-bit-graphic
+ latin-iso8859-1
+ mule-unicode-0100-24ff
+ mule-unicode-2500-33ff
+ mule-unicode-e000-ffff)
+ (mime-charset . utf-8)))
+
+(define-coding-system-alias 'utf-8 'mule-utf-8)
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