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bc511a64f6
Most of this change is to boilerplate commentary such as license URLs. This change was prompted by ftp://ftp.gnu.org's going-away party, planned for November. Change these FTP URLs to https://ftp.gnu.org instead. Make similar changes for URLs to other organizations moving away from FTP. Also, change HTTP to HTTPS for URLs to gnu.org and fsf.org when this works, as this will further help defend against man-in-the-middle attacks (for this part I omitted the MS-DOS and MS-Windows sources and the test tarballs to keep the workload down). HTTPS is not fully working to lists.gnu.org so I left those URLs alone for now.
72 lines
2.4 KiB
EmacsLisp
72 lines
2.4 KiB
EmacsLisp
;;; hex-util.el --- Functions to encode/decode hexadecimal string -*- lexical-binding: t -*-
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;; Copyright (C) 1999, 2001-2017 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 GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs 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 GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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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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;;; hex-util.el ends here
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