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1 | ;;; hex-util.el --- Functions to encode/decode hexadecimal string. |
2 | ||
73b0cd50 | 3 | ;; Copyright (C) 1999, 2001-2011 Free Software Foundation, Inc. |
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4 | |
5 | ;; Author: Shuhei KOBAYASHI <shuhei@aqua.ocn.ne.jp> | |
6 | ;; Keywords: data | |
7 | ||
8 | ;; This file is part of GNU Emacs. | |
9 | ||
eb3fa2cf | 10 | ;; GNU Emacs is free software: you can redistribute it and/or modify |
06cec913 | 11 | ;; it under the terms of the GNU General Public License as published by |
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12 | ;; the Free Software Foundation, either version 3 of the License, or |
13 | ;; (at your option) any later version. | |
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14 | |
15 | ;; GNU Emacs 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 | |
eb3fa2cf | 21 | ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. |
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22 | |
23 | ;;; Commentary: | |
24 | ||
25 | ;;; Code: | |
26 | ||
27 | (eval-when-compile | |
28 | (defmacro hex-char-to-num (chr) | |
29 | `(let ((chr ,chr)) | |
30 | (cond | |
31 | ((and (<= ?a chr)(<= chr ?f)) (+ (- chr ?a) 10)) | |
32 | ((and (<= ?A chr)(<= chr ?F)) (+ (- chr ?A) 10)) | |
33 | ((and (<= ?0 chr)(<= chr ?9)) (- chr ?0)) | |
34 | (t (error "Invalid hexadecimal digit `%c'" chr))))) | |
35 | (defmacro num-to-hex-char (num) | |
36 | `(aref "0123456789abcdef" ,num))) | |
37 | ||
38 | (defun decode-hex-string (string) | |
39 | "Decode hexadecimal STRING to octet string." | |
40 | (let* ((len (length string)) | |
41 | (dst (make-string (/ len 2) 0)) | |
42 | (idx 0)(pos 0)) | |
43 | (while (< pos len) | |
44 | ;; logior and lsh are not byte-coded. | |
45 | ;; (aset dst idx (logior (lsh (hex-char-to-num (aref string pos)) 4) | |
46 | ;; (hex-char-to-num (aref string (1+ pos))))) | |
47 | (aset dst idx (+ (* (hex-char-to-num (aref string pos)) 16) | |
48 | (hex-char-to-num (aref string (1+ pos))))) | |
49 | (setq idx (1+ idx) | |
50 | pos (+ 2 pos))) | |
51 | dst)) | |
52 | ||
53 | (defun encode-hex-string (string) | |
54 | "Encode octet STRING to hexadecimal string." | |
55 | (let* ((len (length string)) | |
56 | (dst (make-string (* len 2) 0)) | |
57 | (idx 0)(pos 0)) | |
58 | (while (< pos len) | |
59 | ;; logand and lsh are not byte-coded. | |
60 | ;; (aset dst idx (num-to-hex-char (logand (lsh (aref string pos) -4) 15))) | |
61 | (aset dst idx (num-to-hex-char (/ (aref string pos) 16))) | |
62 | (setq idx (1+ idx)) | |
63 | ;; (aset dst idx (num-to-hex-char (logand (aref string pos) 15))) | |
64 | (aset dst idx (num-to-hex-char (% (aref string pos) 16))) | |
65 | (setq idx (1+ idx) | |
66 | pos (1+ pos))) | |
67 | dst)) | |
68 | ||
69 | (provide 'hex-util) | |
70 | ||
06cec913 | 71 | ;;; hex-util.el ends here |