Merge semi21-D20010129.

[elisp/lemi.git] / mail / hex-util.el

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+;;; hex-util.el --- Functions to encode/decode hexadecimal string.
+
+;; Copyright (C) 1999 Shuhei KOBAYASHI
+
+;; Author: Shuhei KOBAYASHI <shuhei@aqua.ocn.ne.jp>
+;; Keywords: data
+
+;; This file is part of FLIM (Faithful Library about Internet Message).
+
+;; This program 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.
+
+;; This program 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 this program; see the file COPYING.  If not, write to
+;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+;; Boston, MA 02111-1307, USA.
+
+;;; Commentary:
+
+;;; Code:
+
+(eval-when-compile
+  (defmacro hex-char-to-num (chr)
+    (` (let ((chr (, chr)))
+        (cond
+         ((and (<= ?a chr)(<= chr ?f)) (+ (- chr ?a) 10))
+         ((and (<= ?A chr)(<= chr ?F)) (+ (- chr ?A) 10))
+         ((and (<= ?0 chr)(<= chr ?9)) (- chr ?0))
+         (t (error "Invalid hexadecimal digit `%c'" chr))))))
+  (defmacro num-to-hex-char (num)
+    (` (aref "0123456789abcdef" (, num)))))
+
+(defun decode-hex-string (string)
+  "Decode hexadecimal STRING to octet string."
+  (let* ((len (length string))
+        (dst (make-string (/ len 2) 0))
+        (idx 0)(pos 0))
+    (while (< pos len)
+;;; logior and lsh are not byte-coded.
+;;;  (aset dst idx (logior (lsh (hex-char-to-num (aref string pos)) 4)
+;;;                        (hex-char-to-num (aref string (1+ pos)))))
+      (aset dst idx (+ (* (hex-char-to-num (aref string pos)) 16)
+                      (hex-char-to-num (aref string (1+ pos)))))
+      (setq idx (1+ idx)
+            pos (+ 2 pos)))
+    dst))
+
+(defun encode-hex-string (string)
+  "Encode octet STRING to hexadecimal string."
+  (let* ((len (length string))
+        (dst (make-string (* len 2) 0))
+        (idx 0)(pos 0))
+    (while (< pos len)
+;;; logand and lsh are not byte-coded.
+;;;  (aset dst idx (num-to-hex-char (logand (lsh (aref string pos) -4) 15)))
+      (aset dst idx (num-to-hex-char (/ (aref string pos) 16)))
+      (setq idx (1+ idx))
+;;;  (aset dst idx (num-to-hex-char (logand (aref string pos) 15)))
+      (aset dst idx (num-to-hex-char (% (aref string pos) 16)))
+      (setq idx (1+ idx)
+            pos (1+ pos)))
+    dst))
+
+(provide 'hex-util)
+
+;;; hex-util.el ends here