;;; utf-16.el --- UTF-16 encoding/decoding ;; Copyright (C) 2001, 2002 Free Software Foundation, Inc. ;; Author: Dave Love ;; 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., 59 Temple Place - Suite 330, ;; Boston, MA 02111-1307, USA. ;;; Commentary: ;; Support for UTF-16, which is a two-byte encoding (modulo ;; surrogates) of Unicode, written either in little or big endian ;; order: coding-systems `mule-utf-16-le' and `mule-utf-16-be'. ;; (utf-16-le is used by the DozeN'T clipboard, for instance.) The ;; data are preceeded by a two-byte signature which identifies their ;; byte sex. These are used by the coding-category-utf-16-{b,l}e code ;; to identify the coding, but ignored on decoding. ;; 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. ;; We'd need new charsets distinct from ascii and eight-bit-control to ;; deal with untranslated sequences, since we can't otherwise ;; distinguish the bytes, as we can with utf-8. ;; ;; Do a multibyte write for bytes in r3 and r4. ;; ;; Intended for untranslatable utf-16 sequences. ;; (define-ccl-program ccl-mule-utf-16-untrans ;; `(0 ;; (if (r3 < 128) ;; (r0 = ,(charset-id 'ascii)) ;; (if (r3 < 160) ;; (r0 = ,(charset-id 'eight-bit-control)) ;; (r0 = ,(charset-id 'eight-bit-graphic)))) ;; (if (r4 < 128) ;; (r0 = ,(charset-id 'ascii)) ;; (if (r4 < 160) ;; (r0 = ,(charset-id 'eight-bit-control)) ;; (r0 = ,(charset-id 'eight-bit-graphic)))) ;; (r1 = r4))) ;; "Do a multibyte write for bytes in r3 and r4. ;; First swap them if we're big endian, indicated by r5==0. ;; Intended for untranslatable utf-16 sequences.") ;; Needed in macro expansion, so can't be let-bound. Zapped after use. (eval-and-compile (defconst utf-16-decode-ucs ;; We have the unicode in r1. Output is charset ID in r0, code ;; point in r1. As r6 keeps endian information, the value should ;; not be changed. `((lookup-integer utf-subst-table-for-decode r1 r3) (if r7 ; got a translation ((r0 = r1) (r1 = r3)) (if (r1 < 128) (r0 = ,(charset-id 'ascii)) (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) ; 2 untranslated bytes ;; ;; Assume this is rare, so don't worry about the ;; ;; overhead of the call. ;; (call mule-utf-16-untrans) ((r0 = ,(charset-id 'mule-unicode-e000-ffff)) (r1 = 15037)) ; U+fffd (if (r1 < #xe000) ; surrogate ;; ((call mule-utf-16-untrans) ;; (write-multibyte-character r0 r1) ;; (read r3 r4) ;; (call mule-utf-16-untrans)) ((read r3 r4) (r0 = ,(charset-id 'mule-unicode-e000-ffff)) (r1 = 15037)) ((r0 = ,(charset-id 'mule-unicode-e000-ffff)) (r1 -= #xe000) (r2 = (((r1 / 96) + 32) << 7)) (r1 %= 96) (r1 += (r2 + 32)))))))))))))) (define-ccl-program ccl-decode-mule-utf-16-le `(2 ; 2 bytes -> 1 to 4 bytes ((loop (read r3 r4) (r1 = (r4 <8 r3)) ,utf-16-decode-ucs (translate-character utf-translation-table-for-decode r0 r1) (write-multibyte-character r0 r1) (repeat)))) "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-16-be `(2 ; 2 bytes -> 1 to 4 bytes ((loop (read r3 r4) (r1 = (r3 <8 r4)) ,utf-16-decode-ucs (translate-character utf-translation-table-for-decode r0 r1) (write-multibyte-character r0 r1) (repeat)))) "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'.") (makunbound 'utf-16-decode-ucs) ; done with it (eval-and-compile (defconst utf-16-decode-to-ucs ;; CCL which, given the result of a multibyte read in r0 and r1, ;; sets r0 to the character's Unicode if the charset is one of the ;; basic utf-8 coding system ones. Otherwise set to U+fffd. `(if (r0 == ,(charset-id 'ascii)) (r0 = r1) (if (r0 == ,(charset-id 'latin-iso8859-1)) (r0 = (r1 + 128)) (if (r0 == ,(charset-id 'eight-bit-control)) (r0 = r1) (if (r0 == ,(charset-id 'eight-bit-graphic)) (r0 = r1) ((r2 = (r1 & #x7f)) (r1 >>= 7) (r3 = ((r1 - 32) * 96)) (r3 += (r2 - 32)) (if (r0 == ,(charset-id 'mule-unicode-0100-24ff)) (r0 = (r3 + #x100)) (if (r0 == ,(charset-id 'mule-unicode-2500-33ff)) (r0 = (r3 + #x2500)) (if (r0 == ,(charset-id 'mule-unicode-e000-ffff)) (r0 = (r3 + #xe000)) (r0 = #xfffd))))))))))) (define-ccl-program ccl-encode-mule-utf-16-le `(1 ((loop (read-multibyte-character r0 r1) (lookup-character utf-subst-table-for-encode r0 r1) (if (r7 == 0) ((translate-character utf-translation-table-for-encode r0 r1) ,utf-16-decode-to-ucs)) (write (r0 & 255)) (write (r0 >> 8)) (repeat)))) "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-16-be `(1 ((loop (read-multibyte-character r0 r1) (lookup-character utf-subst-table-for-encode r0 r1) (if (r7 == 0) ((translate-character utf-translation-table-for-encode r0 r1) ,utf-16-decode-to-ucs)) (write (r0 >> 8)) (write (r0 & 255)) (repeat)))) "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.") (makunbound 'utf-16-decode-to-ucs) (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).")) (make-coding-system 'mule-utf-16-le 4 ?u ; Mule-UCS uses ?U, but code-pages uses that for koi8-u. (concat "Little endian UTF-16 encoding for Emacs-supported Unicode characters." doc) '(ccl-decode-mule-utf-16-le . ccl-encode-mule-utf-16-le) '((safe-charsets ascii eight-bit-control latin-iso8859-1 mule-unicode-0100-24ff mule-unicode-2500-33ff mule-unicode-e000-ffff) (mime-charset . utf-16le) (coding-category . coding-category-utf-16-le) (valid-codes (0 . 255)) (dependency unify-8859-on-encoding-mode unify-8859-on-decoding-mode utf-fragment-on-decoding utf-translate-cjk))) (make-coding-system 'mule-utf-16-be 4 ?u (concat "Big endian UTF-16 encoding for Emacs-supported Unicode characters." doc) '(ccl-decode-mule-utf-16-be . ccl-encode-mule-utf-16-be) '((safe-charsets ascii eight-bit-control latin-iso8859-1 mule-unicode-0100-24ff mule-unicode-2500-33ff mule-unicode-e000-ffff) (mime-charset . utf-16be) (coding-category . coding-category-utf-16-be) (valid-codes (0 . 255)) (dependency unify-8859-on-encoding-mode unify-8859-on-decoding-mode utf-fragment-on-decoding utf-translate-cjk)))) (define-coding-system-alias 'utf-16-le 'mule-utf-16-le) (define-coding-system-alias 'utf-16-be 'mule-utf-16-be) ;;; utf-16.el ends here