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;;; hex-util.el --- Functions to encode/decode hexadecimal string. |
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;; Copyright (C) 1999, 2001 Free Software Foundation, Inc. |
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;; Author: Shuhei KOBAYASHI <shuhei@aqua.ocn.ne.jp> |
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;; Keywords: data |
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;; This file is part of FLIM (Faithful Library about Internet Message). |
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;; This program is free software; you can redistribute it and/or |
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;; modify it under the terms of the GNU General Public License as |
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;; published by the Free Software Foundation; either version 2, or |
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;; (at your option) any later version. |
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;; This program is distributed in the hope that it will be useful, |
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of |
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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;; GNU General Public License for more details. |
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;; You should have received a copy of the GNU General Public License |
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;; along with this program; see the file COPYING. If not, write to |
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;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
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;; Boston, MA 02111-1307, USA. |
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;;; Commentary: |
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;;; Code: |
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(eval-when-compile |
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(defmacro hex-char-to-num (chr) |
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(` (let ((chr (, chr))) |
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(cond |
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((and (<= ?a chr)(<= chr ?f)) (+ (- chr ?a) 10)) |
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((and (<= ?A chr)(<= chr ?F)) (+ (- chr ?A) 10)) |
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((and (<= ?0 chr)(<= chr ?9)) (- chr ?0)) |
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(t (error "Invalid hexadecimal digit `%c'" chr)))))) |
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(defmacro num-to-hex-char (num) |
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(` (aref "0123456789abcdef" (, num))))) |
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(defun decode-hex-string (string) |
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"Decode hexadecimal STRING to octet string." |
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(let* ((len (length string)) |
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(dst (make-string (/ len 2) 0)) |
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(idx 0)(pos 0)) |
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(while (< pos len) |
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;;; logior and lsh are not byte-coded. |
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;;; (aset dst idx (logior (lsh (hex-char-to-num (aref string pos)) 4) |
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;;; (hex-char-to-num (aref string (1+ pos))))) |
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(aset dst idx (+ (* (hex-char-to-num (aref string pos)) 16) |
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(hex-char-to-num (aref string (1+ pos))))) |
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(setq idx (1+ idx) |
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pos (+ 2 pos))) |
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dst)) |
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(defun encode-hex-string (string) |
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"Encode octet STRING to hexadecimal string." |
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(let* ((len (length string)) |
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(dst (make-string (* len 2) 0)) |
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(idx 0)(pos 0)) |
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(while (< pos len) |
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;;; logand and lsh are not byte-coded. |
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;;; (aset dst idx (num-to-hex-char (logand (lsh (aref string pos) -4) 15))) |
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(aset dst idx (num-to-hex-char (/ (aref string pos) 16))) |
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(setq idx (1+ idx)) |
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;;; (aset dst idx (num-to-hex-char (logand (aref string pos) 15))) |
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(aset dst idx (num-to-hex-char (% (aref string pos) 16))) |
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(setq idx (1+ idx) |
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pos (1+ pos))) |
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dst)) |
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(provide 'hex-util) |
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;;; arch-tag: fe8aaa79-6c86-400e-813f-5a8cc4cb3859 |
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;;; hex-util.el ends here |