;;; eexec.el --- hex and eexec encoder / decoder

;; Copyright (C) 1999 Roger Willcocks
;; rogerw@centipede.co.uk
;;
;; This program 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 2 of
;; the License, or (at your option) any later version.

;; This program 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 this program; if not, write to the Free Software Foundation, Inc.,
;; 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.

;;; Commentary:

;; commands to turn a region from binary to hex and vice-versa
;; commands to eexec encode and decode a region

;;; Code:

(defun eexec-region ()
  "ascii to PS"
  (interactive)
  (let ((from (region-beginning))
	(to (region-end))
	(i 0)
	(j 0)
	(k 0)
	(ival 0)
	(R 55665)
	str len cval)
	
    (setq str (buffer-substring from to))
    (setq len (length str))

    (goto-char from)
    (kill-region from to)
	
    (while (< i len)
	  
      (setq cval (aref str i))
      (setq i (1+ i))

      (progn
	(setq ival (logxor cval (/ R 256)))
	(setq R (logand (+ 22719 (* 52845 (+ ival R))) 65535))
	(insert (aref "0123456789abcdef" (logand 15 (/ ival 16))))
	(insert (aref "0123456789abcdef" (logand 15 ival)))
	(setq k (1+ k))
	)

      (if (eq 0 (% k 30))
	  (insert 10)
	)
      )
    )
  )


(defun uneexec-region ()
  "PS to ascii"
  (interactive)
  (let ((from (region-beginning))
	(to (region-end))
	(i 0)
	(j 0)
	(R 55665)
	str len cval ival)
	
    (setq str (buffer-substring from to))
    (setq len (length str))
    (setq ival 0)

    (goto-char from)
    (kill-region from to)
	
    (while (< i len)
	  
      (setq cval (aref str i))

      (if (and (>= cval ?0) (<= cval ?9))
	  (progn
	    (setq ival (+ (* 16 ival) (- cval ?0)))
	    (setq j (1+ j))))

      (if (and (>= cval ?a) (<= cval ?f))
	  (progn
	    (setq ival (+ (* 16 ival) (+ 10 (- cval ?a))))
	    (setq j (1+ j))))
		      
      (if (and (>= cval ?A) (<= cval ?F))
	  (progn
	    (setq ival (+ (* 16 ival) (+ 10 (- cval ?A))))
	    (setq j (1+ j))))
		      
      (setq i (1+ i))

      (if (eq j 2)
	  (progn
	    (insert (logand 255 (logxor ival (/ R 256))))
	    (setq R (logand (+ 22719 (* 52845 (+ ival R))) 65535))
	    (setq ival 0)
	    (setq j 0)
	    )
	)
      )
    )
  )


(defun beexec-region ()
  "bin to PS"
  (interactive)
  (let ((from (region-beginning))
	(to (region-end))
	(i 0)
	(j 0)
	(R 55665)
	str len cval ival)
	
    (setq str (buffer-substring from to))
    (setq len (length str))
    (setq ival 0)

    (goto-char from)
    (kill-region from to)
	
    (while (< i len)
      (setq cval (aref str i))
      (setq i (1+ i))
      (setq ival (logxor cval (/ R 256)))
      (setq R (logand (+ 22719 (* 52845 (+ ival R))) 65535))
      (insert (logand 255 ival))
      )
    )
  )


(defun buneexec-region ()
  "PS to bin"
  (interactive)
  (let ((from (region-beginning))
	(to (region-end))
	(i 0)
	(j 0)
	(R 55665)
	str len cval ival)
	
    (setq str (buffer-substring from to))
    (setq len (length str))
    (setq ival 0)

    (goto-char from)
    (kill-region from to)
	
    (while (< i len)
      (setq ival (aref str i))
      (setq i (1+ i))
      (insert (logand 255 (logxor ival (/ R 256))))
      (setq R (logand (+ 22719 (* 52845 (+ ival R))) 65535))
      )
    )
  )


(defun hex-region ()
  "char to hex"
  (interactive)
  (let ((from (region-beginning))
	(to (region-end))
	(i 0)
	(j 0)
	(k 0)
	str len cval ival)
	
    (setq str (buffer-substring from to))
    (setq len (length str))

    (goto-char from)
    (kill-region from to)
	
    (while (< i len)
	  
      (setq cval (aref str i))
      (setq i (1+ i))

      (progn
	(insert (aref "0123456789abcdef" (logand 15 (/ cval 16))))
	(insert (aref "0123456789abcdef" (logand 15 cval)))
	(setq k (1+ k))
	)

      (if (eq 0 (% k 30))
	  (insert 10)
	)
      )
    )
  )


(defun unhex-region ()
  "hex to char"
  (interactive)
  (let ((from (region-beginning))
	(to (region-end))
	(i 0)
	(j 0)
	(ival 0)
	str len cval)
	
    (setq str (buffer-substring from to))
    (setq len (length str))

    (goto-char from)
    (kill-region from to)
	
    (while (< i len)
	  
      (setq cval (aref str i))

      (if (and (>= cval ?0) (<= cval ?9))
	  (progn
	    (setq ival (+ (* 16 ival) (- cval ?0)))
	    (setq j (1+ j))))

      (if (and (>= cval ?a) (<= cval ?f))
	  (progn
	    (setq ival (+ (* 16 ival) (+ 10 (- cval ?a))))
	    (setq j (1+ j))))
		      
      (if (and (>= cval ?A) (<= cval ?F))
	  (progn
	    (setq ival (+ (* 16 ival) (+ 10 (- cval ?A))))
	    (setq j (1+ j))))
		      
      (setq i (1+ i))

      (if (eq j 2)
	  (progn
	    (insert ival)
	    (setq ival 0)
	    (setq j 0)
	    )
	)
      )
    )
  )

;;; eexec.el ends here