+;;; @ internal base64 decoder
+;;;
+
+(defconst base64-numbers
+ (eval-when-compile
+ (let ((len (length base64-characters))
+ (vec (make-vector 123 nil))
+ (i 0))
+ (while (< i len)
+ (aset vec (aref base64-characters i) i)
+ (setq i (1+ i)))
+ vec)))
+
+(defmacro base64-char-to-num (c)
+ `(aref base64-numbers ,c))
+
+(defsubst base64-internal-decode (string buffer)
+ (let* ((len (length string))
+ (i 0)
+ (j 0)
+ v1 v2 v3)
+ (catch 'tag
+ (while (< i len)
+ (when (prog1 (setq v1 (base64-char-to-num (aref string i)))
+ (setq i (1+ i)))
+ (setq v2 (base64-char-to-num (aref string i))
+ i (1+ i)
+ v3 (base64-char-to-num (aref string i))
+ i (1+ i))
+ (aset buffer j (logior (lsh v1 2)(lsh v2 -4)))
+ (setq j (1+ j))
+ (if v3
+ (let ((v4 (base64-char-to-num (aref string i))))
+ (setq i (1+ i))
+ (aset buffer j (logior (lsh (logand v2 15) 4)(lsh v3 -2)))
+ (setq j (1+ j))
+ (if v4
+ (aset buffer (prog1 j (setq j (1+ j)))
+ (logior (lsh (logand v3 3) 6) v4))
+ (throw 'tag nil)
+ ))
+ (throw 'tag nil)
+ ))))
+ (substring buffer 0 j)
+ ))
+
+(defun base64-internal-decode-string (string)
+ (base64-internal-decode string (make-string (length string) 0)))
+
+;; (defsubst base64-decode-string! (string)
+;; (setq string (string-as-unibyte string))
+;; (base64-internal-decode string string))
+
+(defun base64-internal-decode-region (beg end)
+ (save-excursion
+ (let ((str (string-as-unibyte (buffer-substring beg end))))
+ (delete-region beg end)
+ (goto-char beg)
+ (insert (base64-internal-decode str str)))))
+
+;; (defun base64-internal-decode-region2 (beg end)
+;; (save-excursion
+;; (let ((str (buffer-substring beg end)))
+;; (delete-region beg end)
+;; (goto-char beg)
+;; (insert (base64-decode-string! str)))))
+
+;; (defun base64-internal-decode-region3 (beg end)
+;; (save-excursion
+;; (let ((str (buffer-substring beg end)))
+;; (delete-region beg end)
+;; (goto-char beg)
+;; (insert (base64-internal-decode-string str)))))
+
+
+;;; @ external encoder/decoder