+(defvar big5-to-cns (make-translation-table)
+ "Translation table for encoding to `euc-tw'.")
+;; Could have been done by china-util loaded before.
+(unless (get 'big5-to-cns 'translation-table)
+ (define-translation-table 'big5-to-cns big5-to-cns))
+
+(define-ccl-program ccl-decode-euc-tw
+ ;; CNS plane 1 needs either two or four bytes in EUC-TW encoding;
+ ;; CNS planes 2 to 7 always need four bytes. In internal encoding of
+ ;; Emacs, CNS planes 1 and 2 need three bytes, and planes 3 to 7 need
+ ;; four bytes. Thus a buffer magnification value of 2 (for both
+ ;; encoding and decoding) is sufficient.
+ `(2
+ ;; we don't have enough registers to hold all charset-ids
+ ((r4 = ,(charset-id 'chinese-cns11643-1))
+ (r5 = ,(charset-id 'chinese-cns11643-2))
+ (r6 = ,(charset-id 'chinese-cns11643-3))
+ (loop
+ (read-if (r0 < #x80)
+ ;; ASCII
+ (write-repeat r0)
+ ;; not ASCII
+ (if (r0 == #x8E)
+ ;; single shift
+ (read-if (r1 < #xA1)
+ ;; invalid byte
+ ((write r0)
+ (write-repeat r1))
+ (if (r1 > #xA7)
+ ;; invalid plane
+ ((write r0)
+ (write-repeat r1))
+ ;; OK, we have a plane
+ (read-if (r2 < #xA1)
+ ;; invalid first byte
+ ((write r0 r1)
+ (write-repeat r2))
+ (read-if (r3 < #xA1)
+ ;; invalid second byte
+ ((write r0 r1 r2)
+ (write-repeat r3))
+ ;; CNS 1-7, finally
+ ((branch (r1 - #xA1)
+ (r1 = r4)
+ (r1 = r5)
+ (r1 = r6)
+ (r1 = ,(charset-id 'chinese-cns11643-4))
+ (r1 = ,(charset-id 'chinese-cns11643-5))
+ (r1 = ,(charset-id 'chinese-cns11643-6))
+ (r1 = ,(charset-id 'chinese-cns11643-7)))
+ (r2 = ((((r2 - #x80) << 7) + r3) - #x80))
+ (write-multibyte-character r1 r2)
+ (repeat))))))
+ ;; standard EUC
+ (if (r0 < #xA1)
+ ;; invalid first byte
+ (write-repeat r0)
+ (read-if (r1 < #xA1)
+ ;; invalid second byte
+ ((write r0)
+ (write-repeat r1))
+ ;; CNS 1, finally
+ ((r1 = ((((r0 - #x80) << 7) + r1) - #x80))
+ (write-multibyte-character r4 r1)
+ (repeat)))))))))
+ "CCL program to decode EUC-TW encoding."
+)
+
+(define-ccl-program ccl-encode-euc-tw
+ `(2
+ ;; we don't have enough registers to hold all charset-ids
+ ((r2 = ,(charset-id 'ascii))
+ (r3 = ,(charset-id 'chinese-big5-1))
+ (r4 = ,(charset-id 'chinese-big5-2))
+ (r5 = ,(charset-id 'chinese-cns11643-1))
+ (r6 = ,(charset-id 'chinese-cns11643-2))
+ (loop
+ (read-multibyte-character r0 r1)
+ (if (r0 == r2)
+ (write-repeat r1)
+ (;; Big 5 encoded characters are first translated to CNS
+ (if (r0 == r3)
+ (translate-character big5-to-cns r0 r1)
+ (if (r0 == r4)
+ (translate-character big5-to-cns r0 r1)))
+ (if (r0 == r5)
+ (r0 = #xA1)
+ (if (r0 == r6)
+ (r0 = #xA2)
+ (if (r0 == ,(charset-id 'chinese-cns11643-3))
+ (r0 = #xA3)
+ (if (r0 == ,(charset-id 'chinese-cns11643-4))
+ (r0 = #xA4)
+ (if (r0 == ,(charset-id 'chinese-cns11643-5))
+ (r0 = #xA5)
+ (if (r0 == ,(charset-id 'chinese-cns11643-6))
+ (r0 = #xA6)
+ (if (r0 == ,(charset-id 'chinese-cns11643-7))
+ (r0 = #xA7)
+ ;; not CNS. We use a dummy character which
+ ;; can't occur in EUC-TW encoding to indicate
+ ;; this.
+ (write-repeat #xFF))))))))))
+ (if (r0 != #xA1)
+ ;; single shift and CNS plane
+ ((write #x8E)
+ (write r0)))
+ (write ((r1 >> 7) + #x80))
+ (write ((r1 % #x80) + #x80))
+ (repeat))))
+ "CCL program to encode EUC-TW encoding."
+)
+
+(defun euc-tw-pre-write-conversion (beg end)
+ "Semi-dummy pre-write function effectively to autoload china-util."
+ ;; Ensure translation table is loaded.
+ (require 'china-util)
+ ;; Don't do this again.
+ (coding-system-put 'euc-tw 'pre-write-conversion nil)
+ nil)
+
+(make-coding-system
+ 'euc-tw 4 ?Z
+ "ISO 2022 based EUC encoding for Chinese CNS11643.
+Big5 encoding is accepted for input also (which is then converted to CNS)."
+ '(ccl-decode-euc-tw . ccl-encode-euc-tw)
+ '((safe-charsets ascii
+ chinese-big5-1
+ chinese-big5-2
+ chinese-cns11643-1
+ chinese-cns11643-2
+ chinese-cns11643-3
+ chinese-cns11643-4
+ chinese-cns11643-5
+ chinese-cns11643-6
+ chinese-cns11643-7)
+ (valid-codes (0 . 255))
+ (pre-write-conversion . euc-tw-pre-write-conversion)))
+
+(define-coding-system-alias 'euc-taiwan 'euc-tw)
+
+(set-language-info-alist
+ "Chinese-CNS" '((charset chinese-cns11643-1 chinese-cns11643-2
+ chinese-cns11643-3 chinese-cns11643-4
+ chinese-cns11643-5 chinese-cns11643-6
+ chinese-cns11643-7)
+ (coding-system iso-2022-cn euc-tw)
+ (coding-priority iso-2022-cn euc-tw chinese-big5
+ chinese-iso-8bit)
+ (features china-util)
+ (input-method . "chinese-cns-quick")
+ (documentation . "\
+Support for Chinese CNS character sets. Note that the EUC-TW coding system
+accepts Big5 for input also (which is then converted to CNS)."))
+ '("Chinese"))