code.delx.au - gnu-emacs/blob - lisp/gnus/hex-util.el

   1 ;;; hex-util.el --- Functions to encode/decode hexadecimal string.
   2
   3 ;; Copyright (C) 1999, 2001  Free Software Foundation, Inc.
   4
   5 ;; Author: Shuhei KOBAYASHI <shuhei@aqua.ocn.ne.jp>
   6 ;; Keywords: data
   7
   8 ;; This file is part of FLIM (Faithful Library about Internet Message).
   9
  10 ;; This program is free software; you can redistribute it and/or
  11 ;; modify it under the terms of the GNU General Public License as
  12 ;; published by the Free Software Foundation; either version 2, or
  13 ;; (at your option) any later version.
  14
  15 ;; This program is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with this program; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;;; Code:
  28
  29 (eval-when-compile
  30   (defmacro hex-char-to-num (chr)
  31     (` (let ((chr (, chr)))
  32          (cond
  33           ((and (<= ?a chr)(<= chr ?f)) (+ (- chr ?a) 10))
  34           ((and (<= ?A chr)(<= chr ?F)) (+ (- chr ?A) 10))
  35           ((and (<= ?0 chr)(<= chr ?9)) (- chr ?0))
  36           (t (error "Invalid hexadecimal digit `%c'" chr))))))
  37   (defmacro num-to-hex-char (num)
  38     (` (aref "0123456789abcdef" (, num)))))
  39
  40 (defun decode-hex-string (string)
  41   "Decode hexadecimal STRING to octet string."
  42   (let* ((len (length string))
  43          (dst (make-string (/ len 2) 0))
  44          (idx 0)(pos 0))
  45     (while (< pos len)
  46 ;;; logior and lsh are not byte-coded.
  47 ;;;  (aset dst idx (logior (lsh (hex-char-to-num (aref string pos)) 4)
  48 ;;;                         (hex-char-to-num (aref string (1+ pos)))))
  49       (aset dst idx (+ (* (hex-char-to-num (aref string pos)) 16)
  50                        (hex-char-to-num (aref string (1+ pos)))))
  51       (setq idx (1+ idx)
  52             pos (+ 2 pos)))
  53     dst))
  54
  55 (defun encode-hex-string (string)
  56   "Encode octet STRING to hexadecimal string."
  57   (let* ((len (length string))
  58          (dst (make-string (* len 2) 0))
  59          (idx 0)(pos 0))
  60     (while (< pos len)
  61 ;;; logand and lsh are not byte-coded.
  62 ;;;  (aset dst idx (num-to-hex-char (logand (lsh (aref string pos) -4) 15)))
  63       (aset dst idx (num-to-hex-char (/ (aref string pos) 16)))
  64       (setq idx (1+ idx))
  65 ;;;  (aset dst idx (num-to-hex-char (logand (aref string pos) 15)))
  66       (aset dst idx (num-to-hex-char (% (aref string pos) 16)))
  67       (setq idx (1+ idx)
  68             pos (1+ pos)))
  69     dst))
  70
  71 (provide 'hex-util)
  72
  73 ;;; arch-tag: fe8aaa79-6c86-400e-813f-5a8cc4cb3859
  74 ;;; hex-util.el ends here