(base64-numbers): New constant.

(base64-char-to-num): New macro.
(base64-internal-decode-string): Don't use memq.

diff --git a/mel-b.el b/mel-b.el
index 205b4fe..93e4f89 100644 (file)
--- a/mel-b.el
+++ b/mel-b.el
@@ -70,45 +70,57 @@ external decoder is called."
 ;;; @ internal base64 decoder
 ;;;
 
-(defsubst base64-char-to-num (c)
-  (cond ((and (<= ?A c) (<= c ?Z)) (- c ?A))
-       ((and (<= ?a c) (<= c ?z)) (+ (- c ?a) 26))
-       ((and (<= ?0 c) (<= c ?9)) (+ (- c ?0) 52))
-       ((= c ?+) 62)
-       ((= c ?/) 63)
-       ((= c ?=) nil)
-       (t (error "not a base64 character %c" c))))
+;; (defsubst base64-char-to-num (c)
+;;   (cond ((and (<= ?A c) (<= c ?Z)) (- c ?A))
+;;         ((and (<= ?a c) (<= c ?z)) (+ (- c ?a) 26))
+;;         ((and (<= ?0 c) (<= c ?9)) (+ (- c ?0) 52))
+;;         ((= c ?+) 62)
+;;         ((= c ?/) 63)
+;;         ((= c ?=) nil)
+;;         (t (error "not a base64 character %c" c))))
+
+(defconst base64-numbers
+  [nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil 63
+   nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil nil
+   nil nil nil nil nil nil nil nil nil nil nil 62  nil nil nil nil
+   52  53  54  55  56  57  58  59  60  61  nil nil nil nil nil nil
+   nil  0   1   2   3   4   5   6   7   8   9  10  11  12  13  14
+   15  16  17  18  19  20  21  22  23  24  25  nil nil nil nil nil
+   nil 26  27  28  29  30  31  32  33  34  35  36  37  38  39  40
+   41  42  43  44  45  46  47  48  49  50  51])
+
+(defmacro base64-char-to-num (c)
+  `(aref base64-numbers ,c))
 
 (defun base64-internal-decode-string (string)
   (let* ((len (length string))
         (i 0)
         (dest (make-string len 0))
-        (j 0))
+        (j 0)
+        v1 v2 v3)
     (catch 'tag
       (while (< i len)
-       (let ((c (aref string i)))
-         (setq i (1+ i))
-         (unless (memq c '(?\x0d ?\x0a))
-           (let ((v1 (base64-char-to-num c))
-                 (v2 (base64-char-to-num (aref string (prog1 i
-                                                        (setq i (1+ i))))))
-                 (v3 (base64-char-to-num (aref string (prog1 i
-                                                        (setq i (1+ i)))))))
-             (aset dest 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 dest j (logior (lsh (logand v2 15) 4)(lsh v3 -2)))
-                   (setq j (1+ j))
-                   (if v4
-                       (aset dest (prog1 j (setq j (1+ j)))
-                             (logior (logand (lsh (logand v3 15) 6) 255)
-                                     v4))
-                     (throw 'tag nil)
-                     ))
-               (throw 'tag nil)
-               ))))))
+       (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 dest 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 dest j (logior (lsh (logand v2 15) 4)(lsh v3 -2)))
+               (setq j (1+ j))
+               (if v4
+                   (aset dest (prog1 j (setq j (1+ j)))
+                         (logior (logand (lsh (logand v3 15) 6) 255)
+                                 v4))
+                 (throw 'tag nil)
+                 ))
+           (throw 'tag nil)
+           ))))
     (substring dest 0 j)
     ))