mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-11-22 07:09:54 +00:00
72 lines
2.4 KiB
EmacsLisp
72 lines
2.4 KiB
EmacsLisp
;;; hex-util.el --- Functions to encode/decode hexadecimal string -*- lexical-binding: t -*-
|
|
|
|
;; Copyright (C) 1999, 2001-2020 Free Software Foundation, Inc.
|
|
|
|
;; Author: Shuhei KOBAYASHI <shuhei@aqua.ocn.ne.jp>
|
|
;; Keywords: data
|
|
|
|
;; This file is part of GNU Emacs.
|
|
|
|
;; GNU Emacs 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 3 of the License, or
|
|
;; (at your option) any later version.
|
|
|
|
;; GNU Emacs 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 GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
;;; 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
|