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emacs/lisp/international/utf-16.el
Kenichi Handa a9be26751c Declare that all UTF-16-based coding
systems ASCII-incompatible.
2005-07-07 06:18:59 +00:00

580 lines
18 KiB
EmacsLisp

;;; utf-16.el --- UTF-16 encoding/decoding
;; Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
;; Copyright (C) 2002, 2003, 2004
;; National Institute of Advanced Industrial Science and Technology (AIST)
;; Registration Number H14PRO021
;; Author: Dave Love <fx@gnu.org>
;; Keywords: Unicode, UTF-16, i18n
;; 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., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
;;; Commentary:
;; Support for UTF-16, which is a two-byte encoding (modulo
;; surrogates) of Unicode, defined in RFC 2781. It is written either
;; in little or big endian order and either with or without the
;; leading BOM (a two-byte signature which identifies their byte sex).
;;
;; We provide these base coding systems.
;; name endian BOM
;; ---- ------ ---
;; mule-utf-16le little no
;; mule-utf-16be big no
;; mule-utf-16le-with-signature little yes
;; mule-utf-16be-with-signature big yes
;; mule-utf-16 both yes
;;
;; Note that un-decodable sequences aren't (yet?) preserved as raw
;; bytes, as they are with utf-8, so reading and writing as utf-16 can
;; corrupt data.
;;; Code:
;; We end up with trivially different -le and -be versions of most
;; things below, sometimes with commonality abstracted into a let
;; binding for maintenance convenience.
;; Needed in macro expansion, so can't be let-bound. Zapped after use.
(eval-and-compile
(defconst utf-16-decode-ucs
;; If r5 is negative, r1 is a Unicode chacter code. Otherise, r5 is
;; the first of a surrogate pair and r1 is the second of the pair.
;; Output is charset ID in r0, code point in r1. R0 may be set to
;; -1 in which case a caller should not write out r1.
`((if (r5 >= 0)
((r0 = (r1 < #xDC00))
(if ((r1 >= #xE000) | r0)
;; Invalid second code of surrogate pair.
((r0 = r5)
(call ccl-mule-utf-untrans))
((r1 -= #xDC00)
(r1 += (((r5 - #xD800) << 10) + #x10000))))
(r5 = -1)))
(if (r1 < 128)
(r0 = ,(charset-id 'ascii))
((lookup-integer utf-subst-table-for-decode r1 r3)
(if r7 ; got a translation
((r0 = r1) (r1 = r3))
(if (r1 < 160)
(r0 = ,(charset-id 'eight-bit-control))
(if (r1 < 256)
((r0 = ,(charset-id 'latin-iso8859-1))
(r1 -= 128))
(if (r1 < #x2500)
((r0 = ,(charset-id 'mule-unicode-0100-24ff))
(r1 -= #x100)
(r2 = (((r1 / 96) + 32) << 7))
(r1 %= 96)
(r1 += (r2 + 32)))
(if (r1 < #x3400)
((r0 = ,(charset-id 'mule-unicode-2500-33ff))
(r1 -= #x2500)
(r2 = (((r1 / 96) + 32) << 7))
(r1 %= 96)
(r1 += (r2 + 32)))
(if (r1 < #xD800)
;; We can't have this character.
((r0 = r1)
(call ccl-mule-utf-untrans)
(r5 = -1)
(r0 = -1))
(if (r1 < #xDC00)
;; The first code of a surrogate pair.
((r5 = r1)
(r0 = -1))
(if (r1 < #xE000)
;; The second code of a surrogate pair, invalid.
((r0 = r1)
(call ccl-mule-utf-untrans)
(r5 = -1)
(r0 = -1))
(if (r1 < #x10000)
((r0 = ,(charset-id 'mule-unicode-e000-ffff))
(r1 -= #xE000)
(r2 = (((r1 / 96) + 32) << 7))
(r1 %= 96)
(r1 += (r2 + 32)))
;; We can't have this character.
((r0 = r1)
(call ccl-mule-utf-untrans)
(r5 = -1)
(r0 = -1)))))))))))))))
(defconst utf-16le-decode-loop
`((r5 = -1)
(loop
(r3 = -1)
(read r3 r4)
(r1 = (r4 <8 r3))
,@utf-16-decode-ucs
(if (r0 >= 0)
((translate-character utf-translation-table-for-decode r0 r1)
(write-multibyte-character r0 r1)))
(repeat))))
(defconst utf-16be-decode-loop
`((r5 = -1)
(loop
(r3 = -1)
(read r3 r4)
(r1 = (r3 <8 r4))
,@utf-16-decode-ucs
(if (r0 >= 0)
((translate-character utf-translation-table-for-decode r0 r1)
(write-multibyte-character r0 r1)))
(repeat))))
)
(define-ccl-program ccl-decode-mule-utf-16le
`(2 ; 2 bytes -> 1 to 4 bytes
,utf-16le-decode-loop
((if (r5 >= 0)
((r0 = r5)
(call ccl-mule-utf-untrans)))
(if (r3 < 0)
nil
((if (r3 < #xA0)
(r0 = ,(charset-id 'eight-bit-control))
(r0 = ,(charset-id 'eight-bit-graphic)))
(write-multibyte-character r0 r3)))))
"Decode UTF-16LE (little endian without signature bytes).
Basic decoding is done into the charsets ascii, latin-iso8859-1 and
mule-unicode-*. Un-representable Unicode characters are decoded as
U+fffd. The result is run through the translation-table named
`utf-translation-table-for-decode'.")
(define-ccl-program ccl-decode-mule-utf-16be
`(2 ; 2 bytes -> 1 to 4 bytes
,utf-16be-decode-loop
((if (r5 >= 0)
((r0 = r5)
(call ccl-mule-utf-untrans)))
(if (r3 >= 0)
((r0 = r3)
(call ccl-mule-utf-untrans)))))
"Decode UTF-16BE (big endian without signature bytes).
Basic decoding is done into the charsets ascii, latin-iso8859-1 and
mule-unicode-*. Un-representable Unicode characters are
decoded as U+fffd. The result is run through the translation-table of
name `utf-translation-table-for-decode'.")
(define-ccl-program ccl-decode-mule-utf-16le-with-signature
`(2
((r3 = -1)
(read r3 r4)
,@utf-16le-decode-loop)
(if (r3 >= 0)
((r0 = r3)
(call ccl-mule-utf-untrans))))
"Like ccl-decode-utf-16le but skip the first 2-byte BOM.")
(define-ccl-program ccl-decode-mule-utf-16be-with-signature
`(2
((r3 = -1)
(read r3 r4)
,@utf-16be-decode-loop)
(if (r3 >= 0)
((r0 = r3)
(call ccl-mule-utf-untrans))))
"Like ccl-decode-utf-16be but skip the first 2-byte BOM.")
(define-ccl-program ccl-decode-mule-utf-16
`(2
((r3 = -1)
(read r3 r4)
(r1 = (r3 <8 r4))
(r5 = -1)
(if (r1 == #xFFFE)
;; R1 is a BOM for little endian. We keep this character as
;; is temporarily. It is removed by post-read-conversion
;; function.
(,@utf-16-decode-ucs
(write-multibyte-character r0 r1)
,@utf-16le-decode-loop)
((if (r1 == #xFEFF)
;; R1 is a BOM for big endian, but we can't keep that
;; character in the output because it can't be
;; distinguished with the normal U+FEFF. So, we keep
;; #xFFFF instead.
((r1 = #xFFFF)
,@utf-16-decode-ucs
(write-multibyte-character r0 r1))
;; R1 is a normal Unicode character.
(,@utf-16-decode-ucs
(if (r0 >= 0)
((translate-character utf-translation-table-for-decode r0 r1)
(write-multibyte-character r0 r1)))))
,@utf-16be-decode-loop)))
(if (r3 >= 0)
((r0 = r3)
(call ccl-mule-utf-untrans))))
"Like ccl-decode-utf-16be/le but check the first BOM.")
(makunbound 'utf-16-decode-ucs) ; done with it
(makunbound 'utf-16le-decode-loop)
(makunbound 'utf-16be-decode-loop)
;; UTF-16 decoder generates an UTF-8 sequence represented by a
;; sequence eight-bit-control/graphic chars for an invalid byte (the
;; last byte of an odd length source) and an untranslatable character
;; (including an invalid surrogate-pair code-point).
;;
;; This CCL parses that sequence (the first byte is already in r1),
;; and if the sequence represents an untranslatable character, it sets
;; r1 to the original invalid code or untranslated Unicode character
;; code, sets r2 to -1 (to prevent r2 and r3 are written), set2 r5 to
;; -1 (to tell the caller that there's no pre-read character).
;;
;; If the sequence represents an invalid byte, it sets r1 to -1, r2 to
;; the byte, sets r3 and r5 to -1.
;;
;; Otherwise, don't change r1, set r2 and r3 to already read
;; eight-bit-control/graphic characters (if any), set r5 and r6 to the
;; last character that invalidates the UTF-8 form.
;;
;; Note: For UTF-8 validation, we only check if a character is
;; eight-bit-control/graphic or not. It may result in incorrect
;; handling of random binary data, but such a data can't be encoded by
;; UTF-16 anyway. At least, UTF-16 decoder doesn't generate such a
;; sequence even if a source contains invalid byte-sequence.
(define-ccl-program ccl-mule-utf-16-encode-untrans
`(0
((r2 = -1)
;; Read the 2nd byte.
(read-multibyte-character r5 r6)
(r0 = (r5 != ,(charset-id 'eight-bit-control)))
(if ((r5 != ,(charset-id 'eight-bit-graphic)) & r0)
((r2 = r1)
(r3 = -1)
(r1 = -1)
(end))) ; invalid UTF-8
(r3 = -1)
(r2 = r6)
(if (r1 <= #xE0)
;; 2-byte UTF-8, i.e. originally an invalid byte.
((r2 &= #x3F)
(r2 |= ((r1 & #x1F) << 6))
(r1 = -1)
(r5 = -1)
(end)))
;; Read the 3rd byte.
(read-multibyte-character r5 r6)
(r0 = (r5 != ,(charset-id 'eight-bit-control)))
(if ((r5 != ,(charset-id 'eight-bit-graphic)) & r0)
((end))) ; invalid UTF-8
(if (r1 < #xF0) ; valid 3-byte UTF-8
((r1 = ((r1 & #x0F) << 12))
(r1 |= ((r2 & #x3F) << 6))
(r1 |= (r6 & #x3F))
(r2 = -1)
(r5 = -1)
(end)))
(r3 = r6)
;; Read the 4th byte.
(read-multibyte-character r5 r6)
(r0 = (r5 != ,(charset-id 'eight-bit-control)))
(if ((r5 != ,(charset-id 'eight-bit-graphic)) & r0)
(end)) ; livalid UTF-8
;; valid 4-byte UTF-8
(r1 = ((r1 & #x07) << 18))
(r1 |= ((r2 & #x3F) << 12))
(r1 |= ((r3 & #x3F) << 6))
(r1 |= (r6 & #x3F))
(r2 = -1)
(r5 = -1)
(end))
(if (r1 >= 0)
((write r1)
(if (r2 >= 0)
((write r2)
(if (r3 >= 0)
(write r3))))))))
(eval-and-compile
(defconst utf-16-decode-to-ucs
;; Read a character and set r1 to the corresponding Unicode code.
;; If r5 is not negative, it means that we have already read a
;; character into r5 and r6.
;; If an invalid eight-bit-control/graphic sequence is found, r2 and
;; r3 may contain a byte to written out, r5 and r6 may contain a
;; pre-read character. Usually they are set to -1.
`((if (r5 < 0)
(read-multibyte-character r0 r1)
((r0 = r5)
(r1 = r6)
(r5 = -1)))
(lookup-character utf-subst-table-for-encode r0 r1)
(r2 = -1)
(if (r7 > 0)
(r1 = r0)
((translate-character utf-translation-table-for-encode r0 r1)
(if (r0 == ,(charset-id 'ascii))
nil
(if (r0 == ,(charset-id 'latin-iso8859-1))
(r1 += 128)
(if (r0 == ,(charset-id 'eight-bit-control))
nil
(if (r0 == ,(charset-id 'eight-bit-graphic))
(call ccl-mule-utf-16-encode-untrans)
((r2 = ((r1 & #x7f) - 32))
(r3 = ((((r1 >> 7) - 32) * 96) + r2))
(r2 = -1)
(r5 = -1)
(if (r0 == ,(charset-id 'mule-unicode-0100-24ff))
(r1 = (r3 + #x100))
(if (r0 == ,(charset-id 'mule-unicode-2500-33ff))
(r1 = (r3 + #x2500))
(if (r0 == ,(charset-id 'mule-unicode-e000-ffff))
(r1 = (r3 + #xe000))
(r1 = #xfffd)))))))))))))
(defconst utf-16le-encode-loop
`((r5 = -1)
(loop
,@utf-16-decode-to-ucs
(if (r1 >= #x10000)
((r1 -= #x10000)
(r0 = ((r1 >> 10) + #xD800))
(write (r0 & 255))
(write (r0 >> 8))
(r1 = ((r1 & #x3FF) + #xDC00))))
(if (r1 >= 0)
((write (r1 & 255))
(write (r1 >> 8))))
(if (r2 >= 0)
((write r2)
(if (r3 >= 0)
(write r3))))
(repeat))))
(defconst utf-16be-encode-loop
`((r5 = -1)
(loop
,@utf-16-decode-to-ucs
(if (r1 >= #x10000)
((r1 -= #x10000)
(r0 = ((r1 >> 10) + #xD800))
(write (r0 >> 8))
(write (r0 & 255))
(r1 = ((r1 & #x3FF) + #xDC00))))
(if (r1 >= 0)
((write (r1 >> 8))
(write (r1 & 255))))
(if (r2 >= 0)
((write r2)
(if (r3 >= 0)
(write r3))))
(repeat))))
)
(define-ccl-program ccl-encode-mule-utf-16le
`(2
,utf-16le-encode-loop)
"Encode to UTF-16LE (little endian without signature).
Characters from the charsets ascii, eight-bit-control,
eight-bit-graphic, latin-iso8859-1 and mule-unicode-* are encoded
after translation through the translation-table of name
`utf-translation-table-for-encode'.
Others are encoded as U+FFFD.")
(define-ccl-program ccl-encode-mule-utf-16be
`(2
,utf-16be-encode-loop)
"Encode to UTF-16BE (big endian without signature).
Characters from the charsets ascii, eight-bit-control,
eight-bit-graphic, latin-iso8859-1 and mule-unicode-* are encoded
after translation through the translation-table named
`utf-translation-table-for-encode'.
Others are encoded as U+FFFD.")
(define-ccl-program ccl-encode-mule-utf-16le-with-signature
`(2
((write #xFF)
(write #xFE)
,@utf-16le-encode-loop))
"Encode to UTF-16 (little endian with signature).
Characters from the charsets ascii, eight-bit-control,
eight-bit-graphic, latin-iso8859-1 and mule-unicode-* are encoded
after translation through the translation-table of name
`utf-translation-table-for-encode'.
Others are encoded as U+FFFD.")
(define-ccl-program ccl-encode-mule-utf-16be-with-signature
`(2
((write #xFE)
(write #xFF)
,@utf-16be-encode-loop))
"Encode to UTF-16 (big endian with signature).
Characters from the charsets ascii, eight-bit-control,
eight-bit-graphic, latin-iso8859-1 and mule-unicode-* are encoded
after translation through the translation-table named
`utf-translation-table-for-encode'.
Others are encoded as U+FFFD.")
(makunbound 'utf-16-decode-to-ucs)
(makunbound 'utf-16le-encode-loop)
(makunbound 'utf-16be-encode-loop)
(defun mule-utf-16-post-read-conversion (length)
(when (> length 0)
(setq length (utf-8-post-read-conversion length))
(let ((char (following-char)))
(cond ((= char (decode-char 'ucs #xFFFE))
(delete-char 1)
(setq last-coding-system-used
(coding-system-change-text-conversion
last-coding-system-used
'mule-utf-16le-with-signature))
(setq length (1- length)))
((= char (decode-char 'ucs #xFFFF))
(delete-char 1)
(setq last-coding-system-used
(coding-system-change-text-conversion
last-coding-system-used
'mule-utf-16be-with-signature))
(setq length (1- length)))
(t
(setq last-coding-system-used 'mule-utf-16be)))))
length)
(let ((doc "
It supports Unicode characters of these ranges:
U+0000..U+33FF, U+E000..U+FFFF.
They correspond to these Emacs character sets:
ascii, latin-iso8859-1, mule-unicode-0100-24ff,
mule-unicode-2500-33ff, mule-unicode-e000-ffff
On decoding (e.g. reading a file), Unicode characters not in the above
ranges are decoded as U+FFFD, effectively corrupting the data
if they are re-encoded.
On encoding (e.g. writing a file), Emacs characters not belonging to
any of the character sets listed above are encoded into the byte
sequence representing U+FFFD (REPLACEMENT CHARACTER).")
(props `((safe-charsets
ascii
eight-bit-control
eight-bit-graphic
latin-iso8859-1
mule-unicode-0100-24ff
mule-unicode-2500-33ff
mule-unicode-e000-ffff
,@(if utf-translate-cjk-mode
utf-translate-cjk-charsets))
(valid-codes (0 . 255))
(mime-text-unsuitable . t)
(pre-write-conversion . utf-8-pre-write-conversion)
(dependency unify-8859-on-encoding-mode
unify-8859-on-decoding-mode
utf-fragment-on-decoding
utf-translate-cjk-mode))))
(make-coding-system
'mule-utf-16le 4
?u ; Mule-UCS uses ?U, but code-pages uses that for koi8-u.
(concat
"UTF-16LE encoding for Emacs-supported Unicode characters."
doc)
'(ccl-decode-mule-utf-16le . ccl-encode-mule-utf-16le)
`(,@props
(post-read-conversion . utf-8-post-read-conversion)
(ascii-incompatible . t)
(mime-charset . utf-16le)))
(make-coding-system
'mule-utf-16be 4 ?u
(concat
"UTF-16BE encoding for Emacs-supported Unicode characters."
doc)
'(ccl-decode-mule-utf-16be . ccl-encode-mule-utf-16be)
`(,@props
(post-read-conversion . utf-8-post-read-conversion)
(ascii-incompatible . t)
(mime-charset . utf-16be)))
(make-coding-system
'mule-utf-16le-with-signature 4 ?u
(concat
"Little endian UTF-16 (with BOM) for Emacs-supported Unicode characters."
doc)
'(ccl-decode-mule-utf-16le-with-signature
. ccl-encode-mule-utf-16le-with-signature)
`(,@props
(post-read-conversion . utf-8-post-read-conversion)
(coding-category . coding-category-utf-16-le)
(ascii-incompatible . t)
(mime-charset . utf-16)))
(make-coding-system
'mule-utf-16be-with-signature 4 ?u
(concat
"Big endian UTF-16 (with BOM) for Emacs-supported Unicode characters."
doc)
'(ccl-decode-mule-utf-16be-with-signature
. ccl-encode-mule-utf-16be-with-signature)
`(,@props
(post-read-conversion . utf-8-post-read-conversion)
(coding-category . coding-category-utf-16-be)
(ascii-incompatible . t)
(mime-charset . utf-16)))
(make-coding-system
'mule-utf-16 4 ?u
(concat
"UTF-16 (with or without BOM) for Emacs-supported Unicode characters."
doc)
'(ccl-decode-mule-utf-16 . ccl-encode-mule-utf-16be-with-signature)
`(,@props
(post-read-conversion . mule-utf-16-post-read-conversion)
(coding-category . coding-category-utf-16-be)
(ascii-incompatible . t)
(mime-charset . utf-16)))
)
(define-coding-system-alias 'utf-16le 'mule-utf-16le)
(define-coding-system-alias 'utf-16be 'mule-utf-16be)
(define-coding-system-alias 'utf-16le-with-signature
'mule-utf-16le-with-signature)
(define-coding-system-alias 'utf-16be-with-signature
'mule-utf-16be-with-signature)
(define-coding-system-alias 'utf-16 'mule-utf-16)
;; For backward compatibility.
(define-coding-system-alias 'mule-utf-16-le 'mule-utf-16le-with-signature)
(define-coding-system-alias 'utf-16-le 'mule-utf-16le-with-signature)
(define-coding-system-alias 'mule-utf-16-be 'mule-utf-16be-with-signature)
(define-coding-system-alias 'utf-16-be 'mule-utf-16be-with-signature)
;;; arch-tag: 85455d46-d9c9-466d-a6f3-c3582a7367c4
;;; utf-16.el ends here