lisp/hexl.el

   1 ;;; hexl.el --- edit a file in a hex dump format using the hexl filter
   2
   3 ;; Copyright (C) 1989, 1994, 1998, 2001, 2002 Free Software Foundation, Inc.
   4
   5 ;; Author: Keith Gabryelski <ag@wheaties.ai.mit.edu>
   6 ;; Maintainer: FSF
   7 ;; Keywords: data
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; This package implements a major mode for editing binary files.  It uses
  29 ;; a program called hexl, supplied with the GNU Emacs distribution, that
  30 ;; can filter a binary into an editable format or from the format back into
  31 ;; binary.  For full instructions, invoke `hexl-mode' on an empty buffer and
  32 ;; do M-x `describe-mode'.
  33 ;;
  34 ;; NOTE: Remember to change `hexl-program' or `hexl-options' if needed.
  35 ;;
  36 ;; Currently hexl only supports big endian hex output with 16 bit
  37 ;; grouping.
  38 ;;
  39 ;; -iso in `hexl-options' will allow iso characters to display in the
  40 ;; ASCII region of the screen (if your emacs supports this) instead of
  41 ;; changing them to dots.
  42
  43 ;;; Code:
  44
  45 ;;
  46 ;; vars here
  47 ;;
  48
  49 (defgroup hexl nil
  50   "Edit a file in a hex dump format using the hexl filter."
  51   :group 'data)
  52
  53
  54 (defcustom hexl-program "hexl"
  55   "The program that will hexlify and dehexlify its stdin.
  56 `hexl-program' will always be concatenated with `hexl-options'
  57 and \"-de\" when dehexlifying a buffer."
  58   :type 'string
  59   :group 'hexl)
  60
  61 (defcustom hexl-iso ""
  62   "If your emacs can handle ISO characters, this should be set to
  63 \"-iso\" otherwise it should be \"\"."
  64   :type 'string
  65   :group 'hexl)
  66
  67 (defcustom hexl-options (format "-hex %s" hexl-iso)
  68   "Space separated options to `hexl-program' that suit your needs.
  69 Quoting cannot be used, so the arguments cannot themselves contain spaces."
  70   :type 'string
  71   :group 'hexl)
  72
  73 (defcustom hexl-follow-ascii t
  74   "If non-nil then highlight the ASCII character corresponding to point."
  75   :type 'boolean
  76   :group 'hexl
  77   :version "20.3")
  78
  79 (defvar hexl-max-address 0
  80   "Maximum offset into hexl buffer.")
  81
  82 (defvar hexl-mode-map nil)
  83
  84 (defvar hexl-mode-old-local-map)
  85 (defvar hexl-mode-old-mode-name)
  86 (defvar hexl-mode-old-major-mode)
  87 (defvar hexl-mode-old-write-contents-hooks)
  88 (defvar hexl-mode-old-require-final-newline)
  89 (defvar hexl-mode-old-syntax-table)
  90
  91 (defvar hexl-ascii-overlay nil
  92   "Overlay used to highlight ASCII element corresponding to current point.")
  93 (make-variable-buffer-local 'hexl-ascii-overlay)
  94
  95 ;; routines
  96
  97 (put 'hexl-mode 'mode-class 'special)
  98
  99 ;;;###autoload
 100 (defun hexl-mode (&optional arg)
 101   "\\<hexl-mode-map>A mode for editing binary files in hex dump format.
 102 This is not an ordinary major mode; it alters some aspects
 103 of the current mode's behavior, but not all; also, you can exit
 104 Hexl mode and return to the previous mode using `hexl-mode-exit'.
 105
 106 This function automatically converts a buffer into the hexl format
 107 using the function `hexlify-buffer'.
 108
 109 Each line in the buffer has an \"address\" (displayed in hexadecimal)
 110 representing the offset into the file that the characters on this line
 111 are at and 16 characters from the file (displayed as hexadecimal
 112 values grouped every 16 bits) and as their ASCII values.
 113
 114 If any of the characters (displayed as ASCII characters) are
 115 unprintable (control or meta characters) they will be replaced as
 116 periods.
 117
 118 If `hexl-mode' is invoked with an argument the buffer is assumed to be
 119 in hexl format.
 120
 121 A sample format:
 122
 123   HEX ADDR: 0001 0203 0405 0607 0809 0a0b 0c0d 0e0f     ASCII-TEXT
 124   --------  ---- ---- ---- ---- ---- ---- ---- ----  ----------------
 125   00000000: 5468 6973 2069 7320 6865 786c 2d6d 6f64  This is hexl-mod
 126   00000010: 652e 2020 4561 6368 206c 696e 6520 7265  e.  Each line re
 127   00000020: 7072 6573 656e 7473 2031 3620 6279 7465  presents 16 byte
 128   00000030: 7320 6173 2068 6578 6164 6563 696d 616c  s as hexadecimal
 129   00000040: 2041 5343 4949 0a61 6e64 2070 7269 6e74   ASCII.and print
 130   00000050: 6162 6c65 2041 5343 4949 2063 6861 7261  able ASCII chara
 131   00000060: 6374 6572 732e 2020 416e 7920 636f 6e74  cters.  Any cont
 132   00000070: 726f 6c20 6f72 206e 6f6e 2d41 5343 4949  rol or non-ASCII
 133   00000080: 2063 6861 7261 6374 6572 730a 6172 6520   characters.are
 134   00000090: 6469 7370 6c61 7965 6420 6173 2070 6572  displayed as per
 135   000000a0: 696f 6473 2069 6e20 7468 6520 7072 696e  iods in the prin
 136   000000b0: 7461 626c 6520 6368 6172 6163 7465 7220  table character
 137   000000c0: 7265 6769 6f6e 2e0a                      region..
 138
 139 Movement is as simple as movement in a normal emacs text buffer.  Most
 140 cursor movement bindings are the same (ie. Use \\[hexl-backward-char], \\[hexl-forward-char], \\[hexl-next-line], and \\[hexl-previous-line]
 141 to move the cursor left, right, down, and up).
 142
 143 Advanced cursor movement commands (ala \\[hexl-beginning-of-line], \\[hexl-end-of-line], \\[hexl-beginning-of-buffer], and \\[hexl-end-of-buffer]) are
 144 also supported.
 145
 146 There are several ways to change text in hexl mode:
 147
 148 ASCII characters (character between space (0x20) and tilde (0x7E)) are
 149 bound to self-insert so you can simply type the character and it will
 150 insert itself (actually overstrike) into the buffer.
 151
 152 \\[hexl-quoted-insert] followed by another keystroke allows you to insert the key even if
 153 it isn't bound to self-insert.  An octal number can be supplied in place
 154 of another key to insert the octal number's ASCII representation.
 155
 156 \\[hexl-insert-hex-char] will insert a given hexadecimal value (if it is between 0 and 0xFF)
 157 into the buffer at the current point.
 158
 159 \\[hexl-insert-octal-char] will insert a given octal value (if it is between 0 and 0377)
 160 into the buffer at the current point.
 161
 162 \\[hexl-insert-decimal-char] will insert a given decimal value (if it is between 0 and 255)
 163 into the buffer at the current point.
 164
 165 \\[hexl-mode-exit] will exit hexl-mode.
 166
 167 Note: saving the file with any of the usual Emacs commands
 168 will actually convert it back to binary format while saving.
 169
 170 You can use \\[hexl-find-file] to visit a file in Hexl mode.
 171
 172 \\[describe-bindings] for advanced commands."
 173   (interactive "p")
 174   (unless (eq major-mode 'hexl-mode)
 175     (let ((modified (buffer-modified-p))
 176           (inhibit-read-only t)
 177           (original-point (1- (point)))
 178           max-address)
 179       (and (eobp) (not (bobp))
 180            (setq original-point (1- original-point)))
 181       (if (not (or (eq arg 1) (not arg)))
 182           ;; if no argument then we guess at hexl-max-address
 183           (setq max-address (+ (* (/ (1- (buffer-size)) 68) 16) 15))
 184         (setq max-address (1- (buffer-size)))
 185         ;; If the buffer's EOL type is -dos, we need to account for
 186         ;; extra CR characters added when hexlify-buffer writes the
 187         ;; buffer to a file.
 188         (when (eq (coding-system-eol-type buffer-file-coding-system) 1)
 189           (setq max-address (+ (count-lines (point-min) (point-max))
 190                                max-address))
 191           ;; But if there's no newline at the last line, we are off by
 192           ;; one; adjust.
 193           (or (eq (char-before (point-max)) ?\n)
 194               (setq max-address (1- max-address)))
 195           (setq original-point (+ (count-lines (point-min) (point))
 196                                   original-point))
 197           (or (bolp) (setq original-point (1- original-point))))
 198         (hexlify-buffer)
 199         (set-buffer-modified-p modified))
 200       (make-local-variable 'hexl-max-address)
 201       (setq hexl-max-address max-address)
 202       (hexl-goto-address original-point))
 203
 204     ;; We do not turn off the old major mode; instead we just
 205     ;; override most of it.  That way, we can restore it perfectly.
 206     (make-local-variable 'hexl-mode-old-local-map)
 207     (setq hexl-mode-old-local-map (current-local-map))
 208     (use-local-map hexl-mode-map)
 209
 210     (make-local-variable 'hexl-mode-old-mode-name)
 211     (setq hexl-mode-old-mode-name mode-name)
 212     (setq mode-name "Hexl")
 213
 214     (make-local-variable 'hexl-mode-old-major-mode)
 215     (setq hexl-mode-old-major-mode major-mode)
 216     (setq major-mode 'hexl-mode)
 217
 218     (make-local-variable 'hexl-mode-old-syntax-table)
 219     (setq hexl-mode-old-syntax-table (syntax-table))
 220     (set-syntax-table (standard-syntax-table))
 221
 222     (make-local-variable 'hexl-mode-old-write-contents-hooks)
 223     (setq hexl-mode-old-write-contents-hooks write-contents-hooks)
 224     (make-local-variable 'write-contents-hooks)
 225     (add-hook 'write-contents-hooks 'hexl-save-buffer)
 226
 227     (make-local-variable 'hexl-mode-old-require-final-newline)
 228     (setq hexl-mode-old-require-final-newline require-final-newline)
 229     (make-local-variable 'require-final-newline)
 230     (setq require-final-newline nil)
 231
 232     ;; Add hooks to rehexlify or dehexlify on various events.
 233     (add-hook 'after-revert-hook 'hexl-after-revert-hook nil t)
 234
 235     (add-hook 'change-major-mode-hook 'hexl-maybe-dehexlify-buffer nil t)
 236
 237     (if hexl-follow-ascii (hexl-follow-ascii 1)))
 238   (run-hooks 'hexl-mode-hook))
 239
 240 (defun hexl-after-revert-hook ()
 241   (setq hexl-max-address (1- (buffer-size)))
 242   (hexlify-buffer)
 243   (set-buffer-modified-p nil))
 244
 245 (defvar hexl-in-save-buffer nil)
 246
 247 (defun hexl-save-buffer ()
 248   "Save a hexl format buffer as binary in visited file if modified."
 249   (interactive)
 250   (if hexl-in-save-buffer nil
 251     (set-buffer-modified-p (if (buffer-modified-p)
 252                                (save-excursion
 253                                  (let ((buf (generate-new-buffer " hexl"))
 254                                        (name (buffer-name))
 255                                        (file-name (buffer-file-name))
 256                                        (start (point-min))
 257                                        (end (point-max))
 258                                        modified)
 259                                    (set-buffer buf)
 260                                    (insert-buffer-substring name start end)
 261                                    (set-buffer name)
 262                                    (dehexlify-buffer)
 263                                    ;; Prevent infinite recursion.
 264                                    (let ((hexl-in-save-buffer t))
 265                                      (save-buffer))
 266                                    (setq modified (buffer-modified-p))
 267                                    (delete-region (point-min) (point-max))
 268                                    (insert-buffer-substring buf start end)
 269                                    (kill-buffer buf)
 270                                    modified))
 271                              (message "(No changes need to be saved)")
 272                              nil))
 273     ;; Return t to indicate we have saved t
 274     t))
 275
 276 ;;;###autoload
 277 (defun hexl-find-file (filename)
 278   "Edit file FILENAME in hexl-mode.
 279 Switch to a buffer visiting file FILENAME, creating one in none exists."
 280   (interactive
 281    (list
 282     (let ((completion-ignored-extensions nil))
 283       (read-file-name "Filename: " nil nil 'ret-must-match))))
 284   (find-file-literally filename)
 285   (if (not (eq major-mode 'hexl-mode))
 286       (hexl-mode)))
 287
 288 (defun hexl-mode-exit (&optional arg)
 289   "Exit Hexl mode, returning to previous mode.
 290 With arg, don't unhexlify buffer."
 291   (interactive "p")
 292   (if (or (eq arg 1) (not arg))
 293       (let ((modified (buffer-modified-p))
 294             (inhibit-read-only t)
 295             (original-point (1+ (hexl-current-address))))
 296         (dehexlify-buffer)
 297         (remove-hook 'write-contents-hooks 'hexl-save-buffer)
 298         (set-buffer-modified-p modified)
 299         (goto-char original-point)
 300         ;; Maybe adjust point for the removed CR characters.
 301         (when (eq (coding-system-eol-type buffer-file-coding-system) 1)
 302           (setq original-point (- original-point
 303                                   (count-lines (point-min) (point))))
 304           (or (bobp) (setq original-point (1+ original-point))))
 305         (goto-char original-point)))
 306
 307   (remove-hook 'after-revert-hook 'hexl-after-revert-hook t)
 308   (remove-hook 'change-major-mode-hook 'hexl-maybe-dehexlify-buffer t)
 309   (remove-hook 'post-command-hook 'hexl-follow-ascii-find t)
 310   (setq hexl-ascii-overlay nil)
 311
 312   (setq write-contents-hooks hexl-mode-old-write-contents-hooks)
 313   (setq require-final-newline hexl-mode-old-require-final-newline)
 314   (setq mode-name hexl-mode-old-mode-name)
 315   (use-local-map hexl-mode-old-local-map)
 316   (set-syntax-table hexl-mode-old-syntax-table)
 317   (setq major-mode hexl-mode-old-major-mode)
 318   (force-mode-line-update))
 319
 320 (defun hexl-maybe-dehexlify-buffer ()
 321   "Convert a hexl format buffer to binary.
 322 Ask the user for confirmation."
 323   (if (y-or-n-p "Convert contents back to binary format? ")
 324       (let ((modified (buffer-modified-p))
 325             (inhibit-read-only t)
 326             (original-point (1+ (hexl-current-address))))
 327         (dehexlify-buffer)
 328         (remove-hook 'write-contents-hooks 'hexl-save-buffer)
 329         (set-buffer-modified-p modified)
 330         (goto-char original-point))))
 331
 332 (defun hexl-current-address (&optional validate)
 333   "Return current hexl-address."
 334   (interactive)
 335   (let ((current-column (- (% (point) 68) 11))
 336         (hexl-address 0))
 337     (if (< current-column 0)
 338         (if validate
 339             (error "Point is not on a character in the file")
 340           (setq current-column 0)))
 341     (setq hexl-address
 342           (+ (* (/ (point) 68) 16)
 343              (if (>= current-column 41)
 344                  (- current-column 41)
 345                (/ (- current-column  (/ current-column 5)) 2))))
 346     (when (interactive-p)
 347       (message "Current address is %d" hexl-address))
 348     hexl-address))
 349
 350 (defun hexl-address-to-marker (address)
 351   "Return buffer position for ADDRESS."
 352   (interactive "nAddress: ")
 353   (+ (* (/ address 16) 68) 11 (/ (* (% address 16) 5) 2)))
 354
 355 (defun hexl-goto-address (address)
 356   "Goto hexl-mode (decimal) address ADDRESS.
 357 Signal error if ADDRESS out of range."
 358   (interactive "nAddress: ")
 359   (if (or (< address 0) (> address hexl-max-address))
 360           (error "Out of hexl region"))
 361   (goto-char (hexl-address-to-marker address)))
 362
 363 (defun hexl-goto-hex-address (hex-address)
 364   "Go to hexl-mode address (hex string) HEX-ADDRESS.
 365 Signal error if HEX-ADDRESS is out of range."
 366   (interactive "sHex Address: ")
 367   (hexl-goto-address (hexl-hex-string-to-integer hex-address)))
 368
 369 (defun hexl-hex-string-to-integer (hex-string)
 370   "Return decimal integer for HEX-STRING."
 371   (interactive "sHex number: ")
 372   (let ((hex-num 0))
 373     (while (not (equal hex-string ""))
 374       (setq hex-num (+ (* hex-num 16)
 375                        (hexl-hex-char-to-integer (string-to-char hex-string))))
 376       (setq hex-string (substring hex-string 1)))
 377     hex-num))
 378
 379 (defun hexl-octal-string-to-integer (octal-string)
 380   "Return decimal integer for OCTAL-STRING."
 381   (interactive "sOctal number: ")
 382   (let ((oct-num 0))
 383     (while (not (equal octal-string ""))
 384       (setq oct-num (+ (* oct-num 8)
 385                        (hexl-oct-char-to-integer
 386                         (string-to-char octal-string))))
 387       (setq octal-string (substring octal-string 1)))
 388     oct-num))
 389
 390 ;; move point functions
 391
 392 (defun hexl-backward-char (arg)
 393   "Move to left ARG bytes (right if ARG negative) in hexl-mode."
 394   (interactive "p")
 395   (hexl-goto-address (- (hexl-current-address) arg)))
 396
 397 (defun hexl-forward-char (arg)
 398   "Move right ARG bytes (left if ARG negative) in hexl-mode."
 399   (interactive "p")
 400   (hexl-goto-address (+ (hexl-current-address) arg)))
 401
 402 (defun hexl-backward-short (arg)
 403   "Move to left ARG shorts (right if ARG negative) in hexl-mode."
 404   (interactive "p")
 405   (hexl-goto-address (let ((address (hexl-current-address)))
 406                        (if (< arg 0)
 407                            (progn
 408                              (setq arg (- arg))
 409                              (while (> arg 0)
 410                                (if (not (equal address (logior address 3)))
 411                                    (if (> address hexl-max-address)
 412                                        (progn
 413                                          (message "End of buffer.")
 414                                          (setq address hexl-max-address))
 415                                      (setq address (logior address 3)))
 416                                  (if (> address hexl-max-address)
 417                                      (progn
 418                                        (message "End of buffer.")
 419                                        (setq address hexl-max-address))
 420                                    (setq address (+ address 4))))
 421                                (setq arg (1- arg)))
 422                              (if (> address hexl-max-address)
 423                                  (progn
 424                                    (message "End of buffer.")
 425                                    (setq address hexl-max-address))
 426                                (setq address (logior address 3))))
 427                          (while (> arg 0)
 428                            (if (not (equal address (logand address -4)))
 429                                (setq address (logand address -4))
 430                              (if (not (equal address 0))
 431                                  (setq address (- address 4))
 432                                (message "Beginning of buffer.")))
 433                            (setq arg (1- arg))))
 434                        address)))
 435
 436 (defun hexl-forward-short (arg)
 437   "Move right ARG shorts (left if ARG negative) in hexl-mode."
 438   (interactive "p")
 439   (hexl-backward-short (- arg)))
 440
 441 (defun hexl-backward-word (arg)
 442   "Move to left ARG words (right if ARG negative) in hexl-mode."
 443   (interactive "p")
 444   (hexl-goto-address (let ((address (hexl-current-address)))
 445                        (if (< arg 0)
 446                            (progn
 447                              (setq arg (- arg))
 448                              (while (> arg 0)
 449                                (if (not (equal address (logior address 7)))
 450                                    (if (> address hexl-max-address)
 451                                        (progn
 452                                          (message "End of buffer.")
 453                                          (setq address hexl-max-address))
 454                                      (setq address (logior address 7)))
 455                                  (if (> address hexl-max-address)
 456                                      (progn
 457                                        (message "End of buffer.")
 458                                        (setq address hexl-max-address))
 459                                    (setq address (+ address 8))))
 460                                (setq arg (1- arg)))
 461                              (if (> address hexl-max-address)
 462                                  (progn
 463                                    (message "End of buffer.")
 464                                    (setq address hexl-max-address))
 465                                (setq address (logior address 7))))
 466                          (while (> arg 0)
 467                            (if (not (equal address (logand address -8)))
 468                                (setq address (logand address -8))
 469                              (if (not (equal address 0))
 470                                  (setq address (- address 8))
 471                                (message "Beginning of buffer.")))
 472                            (setq arg (1- arg))))
 473                        address)))
 474
 475 (defun hexl-forward-word (arg)
 476   "Move right ARG words (left if ARG negative) in hexl-mode."
 477   (interactive "p")
 478   (hexl-backward-word (- arg)))
 479
 480 (defun hexl-previous-line (arg)
 481   "Move vertically up ARG lines [16 bytes] (down if ARG negative) in hexl-mode.
 482 If there is byte at the target address move to the last byte in that line."
 483   (interactive "p")
 484   (hexl-next-line (- arg)))
 485
 486 (defun hexl-next-line (arg)
 487   "Move vertically down ARG lines [16 bytes] (up if ARG negative) in hexl-mode.
 488 If there is no byte at the target address move to the last byte in that line."
 489   (interactive "p")
 490   (hexl-goto-address (let ((address (+ (hexl-current-address) (* arg 16))))
 491                        (if (and (< arg 0) (< address 0))
 492                                 (progn (message "Out of hexl region.")
 493                                        (setq address
 494                                              (% (hexl-current-address) 16)))
 495                          (if (and (> address hexl-max-address)
 496                                   (< (% hexl-max-address 16) (% address 16)))
 497                              (setq address hexl-max-address)
 498                            (if (> address hexl-max-address)
 499                                (progn (message "Out of hexl region.")
 500                                       (setq
 501                                        address
 502                                        (+ (logand hexl-max-address -16)
 503                                           (% (hexl-current-address) 16)))))))
 504                        address)))
 505
 506 (defun hexl-beginning-of-buffer (arg)
 507   "Move to the beginning of the hexl buffer.
 508 Leaves `hexl-mark' at previous position.
 509 With prefix arg N, puts point N bytes of the way from the true beginning."
 510   (interactive "p")
 511   (push-mark (point))
 512   (hexl-goto-address (+ 0 (1- arg))))
 513
 514 (defun hexl-end-of-buffer (arg)
 515   "Go to `hexl-max-address' minus ARG."
 516   (interactive "p")
 517   (push-mark (point))
 518   (hexl-goto-address (- hexl-max-address (1- arg))))
 519
 520 (defun hexl-beginning-of-line ()
 521   "Goto beginning of line in hexl mode."
 522   (interactive)
 523   (goto-char (+ (* (/ (point) 68) 68) 11)))
 524
 525 (defun hexl-end-of-line ()
 526   "Goto end of line in hexl mode."
 527   (interactive)
 528   (hexl-goto-address (let ((address (logior (hexl-current-address) 15)))
 529                        (if (> address hexl-max-address)
 530                            (setq address hexl-max-address))
 531                        address)))
 532
 533 (defun hexl-scroll-down (arg)
 534   "Scroll hexl buffer window upward ARG lines; or near full window if no ARG."
 535   (interactive "P")
 536   (if (null arg)
 537       (setq arg (1- (window-height)))
 538     (setq arg (prefix-numeric-value arg)))
 539   (hexl-scroll-up (- arg)))
 540
 541 (defun hexl-scroll-up (arg)
 542   "Scroll hexl buffer window upward ARG lines; or near full window if no ARG.
 543 If there's no byte at the target address, move to the first or last line."
 544   (interactive "P")
 545   (if (null arg)
 546       (setq arg (1- (window-height)))
 547     (setq arg (prefix-numeric-value arg)))
 548   (let* ((movement (* arg 16))
 549          (address (hexl-current-address))
 550          (dest (+ address movement)))
 551     (cond
 552      ;; If possible, try to stay at the same offset from the beginning
 553      ;; of the 16-byte group, even if we move to the first or last
 554      ;; group.
 555      ((and (> dest hexl-max-address)
 556            (>= (% hexl-max-address 16) (% address 16)))
 557       (setq dest (+ (logand hexl-max-address -16) (% address 16))))
 558      ((> dest hexl-max-address)
 559       (setq dest hexl-max-address))
 560      ((< dest 0)
 561       (setq dest (% address 16))))
 562     (if (/= dest (+ address movement))
 563         (message "Out of hexl region."))
 564     (hexl-goto-address dest)
 565     (recenter 0)))
 566
 567 (defun hexl-beginning-of-1k-page ()
 568   "Go to beginning of 1k boundary."
 569   (interactive)
 570   (hexl-goto-address (logand (hexl-current-address) -1024)))
 571
 572 (defun hexl-end-of-1k-page ()
 573   "Go to end of 1k boundary."
 574   (interactive)
 575   (hexl-goto-address (let ((address (logior (hexl-current-address) 1023)))
 576                        (if (> address hexl-max-address)
 577                            (setq address hexl-max-address))
 578                        address)))
 579
 580 (defun hexl-beginning-of-512b-page ()
 581   "Go to beginning of 512 byte boundary."
 582   (interactive)
 583   (hexl-goto-address (logand (hexl-current-address) -512)))
 584
 585 (defun hexl-end-of-512b-page ()
 586   "Go to end of 512 byte boundary."
 587   (interactive)
 588   (hexl-goto-address (let ((address (logior (hexl-current-address) 511)))
 589                        (if (> address hexl-max-address)
 590                            (setq address hexl-max-address))
 591                        address)))
 592
 593 (defun hexl-quoted-insert (arg)
 594   "Read next input character and insert it.
 595 Useful for inserting control characters and non-ASCII characters given their
 596 numerical code.
 597 You may also type octal digits, to insert a character with that code."
 598   (interactive "p")
 599   (hexl-insert-multibyte-char (read-quoted-char) arg))
 600
 601 ;00000000: 0011 2233 4455 6677 8899 aabb ccdd eeff  0123456789ABCDEF
 602
 603 ;;;###autoload
 604 (defun hexlify-buffer ()
 605   "Convert a binary buffer to hexl format.
 606 This discards the buffer's undo information."
 607   (interactive)
 608   (and buffer-undo-list
 609        (or (y-or-n-p "Converting to hexl format discards undo info; ok? ")
 610            (error "Aborted")))
 611   (setq buffer-undo-list nil)
 612   ;; Don't decode text in the ASCII part of `hexl' program output.
 613   (let ((coding-system-for-read 'raw-text)
 614         (coding-system-for-write buffer-file-coding-system)
 615         (buffer-undo-list t))
 616     (apply 'call-process-region (point-min) (point-max)
 617            (expand-file-name hexl-program exec-directory)
 618            t t nil (split-string hexl-options))
 619     (if (> (point) (hexl-address-to-marker hexl-max-address))
 620         (hexl-goto-address hexl-max-address))))
 621
 622 (defun dehexlify-buffer ()
 623   "Convert a hexl format buffer to binary.
 624 This discards the buffer's undo information."
 625   (interactive)
 626   (and buffer-undo-list
 627        (or (y-or-n-p "Converting from hexl format discards undo info; ok? ")
 628            (error "Aborted")))
 629   (setq buffer-undo-list nil)
 630   (let ((coding-system-for-write 'raw-text)
 631         (coding-system-for-read buffer-file-coding-system)
 632         (buffer-undo-list t))
 633     (apply 'call-process-region (point-min) (point-max)
 634            (expand-file-name hexl-program exec-directory)
 635            t t nil "-de" (split-string hexl-options))))
 636
 637 (defun hexl-char-after-point ()
 638   "Return char for ASCII hex digits at point."
 639   (hexl-htoi (char-after (point))
 640              (char-after (1+ (point)))))
 641
 642 (defun hexl-htoi (lh rh)
 643   "Hex (char) LH (char) RH to integer."
 644     (+ (* (hexl-hex-char-to-integer lh) 16)
 645        (hexl-hex-char-to-integer rh)))
 646
 647 (defun hexl-hex-char-to-integer (character)
 648   "Take a char and return its value as if it was a hex digit."
 649   (if (and (>= character ?0) (<= character ?9))
 650       (- character ?0)
 651     (let ((ch (logior character 32)))
 652       (if (and (>= ch ?a) (<= ch ?f))
 653           (- ch (- ?a 10))
 654         (error "Invalid hex digit `%c'" ch)))))
 655
 656 (defun hexl-oct-char-to-integer (character)
 657   "Take a char and return its value as if it was a octal digit."
 658   (if (and (>= character ?0) (<= character ?7))
 659       (- character ?0)
 660     (error "Invalid octal digit `%c'" character)))
 661
 662 (defun hexl-printable-character (ch)
 663   "Return a displayable string for character CH."
 664   (format "%c" (if hexl-iso
 665                    (if (or (< ch 32) (and (>= ch 127) (< ch 160)))
 666                        46
 667                      ch)
 668                  (if (or (< ch 32) (>= ch 127))
 669                      46
 670                    ch))))
 671
 672 (defun hexl-insert-multibyte-char (ch num)
 673   "Insert a possibly multibyte character CH NUM times.
 674
 675 Non-ASCII characters are first encoded with `buffer-file-coding-system',
 676 and their encoded form is inserted byte by byte."
 677   (let ((charset (char-charset ch))
 678         (coding (if (or (null buffer-file-coding-system)
 679                         ;; coding-system-type equals t means undecided.
 680                         (eq (coding-system-type buffer-file-coding-system) t))
 681                     default-buffer-file-coding-system
 682                   buffer-file-coding-system)))
 683     (cond ((and (> ch 0) (< ch 256))
 684            (hexl-insert-char ch num))
 685           ((eq charset 'unknown)
 686            (error
 687             "0x%x -- invalid character code; use \\[hexl-insert-hex-string]"
 688             ch))
 689           (t
 690            (let ((encoded (encode-coding-char ch coding))
 691                  (internal (string-as-unibyte (char-to-string ch)))
 692                  internal-hex)
 693              ;; If encode-coding-char returns nil, it means our character
 694              ;; cannot be safely encoded with buffer-file-coding-system.
 695              ;; In that case, we offer to insert the internal representation
 696              ;; of that character, byte by byte.
 697              (when (null encoded)
 698                (setq internal-hex
 699                      (mapconcat (function (lambda (c) (format "%x" c)))
 700                                 internal " "))
 701                (if (yes-or-no-p
 702                     (format
 703                      "Insert char 0x%x's internal representation \"%s\"? "
 704                      ch internal-hex))
 705                    (setq encoded internal)
 706                  (error
 707                   "Can't encode `0x%x' with this buffer's coding system; try \\[hexl-insert-hex-string]"
 708                   ch)))
 709              (while (> num 0)
 710                (mapc
 711                 (function (lambda (c) (hexl-insert-char c 1))) encoded)
 712                (setq num (1- num))))))))
 713
 714 (defun hexl-self-insert-command (arg)
 715   "Insert this character.
 716 Interactively, with a numeric argument, insert this character that many times.
 717
 718 Non-ASCII characters are first encoded with `buffer-file-coding-system',
 719 and their encoded form is inserted byte by byte."
 720   (interactive "p")
 721   (hexl-insert-multibyte-char last-command-char arg))
 722
 723 (defun hexl-insert-char (ch num)
 724   "Insert the character CH NUM times in a hexl buffer.
 725
 726 CH must be a unibyte character whose value is between 0 and 255."
 727   (if (or (< ch 0) (> ch 255))
 728       (error "Invalid character 0x%x -- must be in the range [0..255]"))
 729   (let ((address (hexl-current-address t)))
 730     (while (> num 0)
 731       (let ((hex-position
 732              (+ (* (/ address 16) 68)
 733                 11
 734                 (* 2 (% address 16))
 735                 (/ (% address 16) 2)))
 736             (ascii-position
 737              (+ (* (/ address 16) 68) 52 (% address 16)))
 738             at-ascii-position)
 739         (if (= (point) ascii-position)
 740             (setq at-ascii-position t))
 741         (goto-char hex-position)
 742         (delete-char 2)
 743         (insert (format "%02x" ch))
 744         (goto-char ascii-position)
 745         (delete-char 1)
 746         (insert (hexl-printable-character ch))
 747         (or (eq address hexl-max-address)
 748             (setq address (1+ address)))
 749         (hexl-goto-address address)
 750         (if at-ascii-position
 751             (progn
 752               (beginning-of-line)
 753               (forward-char 51)
 754               (forward-char (% address 16)))))
 755       (setq num (1- num)))))
 756
 757 ;; hex conversion
 758
 759 (defun hexl-insert-hex-char (arg)
 760   "Insert a character given by its hexadecimal code ARG times at point."
 761   (interactive "p")
 762   (let ((num (hexl-hex-string-to-integer (read-string "Hex number: "))))
 763     (if (< num 0)
 764         (error "Hex number out of range")
 765       (hexl-insert-multibyte-char num arg))))
 766
 767 (defun hexl-insert-hex-string (str arg)
 768   "Insert hexadecimal string STR at point ARG times.
 769 Embedded whitespace, dashes, and periods in the string are ignored."
 770   (interactive "sHex string: \np")
 771   (setq str (replace-regexp-in-string "[- \t.]" "" str))
 772   (let ((chars '()))
 773     (let ((len (length str))
 774           (idx 0))
 775       (if (eq (logand len 1) 1)
 776           (let ((num (hexl-hex-string-to-integer (substring str 0 1))))
 777             (setq chars (cons num chars))
 778             (setq idx 1)))
 779       (while (< idx len)
 780         (let* ((nidx (+ idx 2))
 781                (num (hexl-hex-string-to-integer (substring str idx nidx))))
 782           (setq chars (cons num chars))
 783           (setq idx nidx))))
 784     (setq chars (nreverse chars))
 785     (while (> arg 0)
 786       (let ((chars chars))
 787         (while chars
 788           (hexl-insert-char (car chars) 1)
 789           (setq chars (cdr chars))))
 790       (setq arg (- arg 1)))))
 791
 792 (defun hexl-insert-decimal-char (arg)
 793   "Insert a character given by its decimal code ARG times at point."
 794   (interactive "p")
 795   (let ((num (string-to-int (read-string "Decimal Number: "))))
 796     (if (< num 0)
 797         (error "Decimal number out of range")
 798       (hexl-insert-multibyte-char num arg))))
 799
 800 (defun hexl-insert-octal-char (arg)
 801   "Insert a character given by its octal code ARG times at point."
 802   (interactive "p")
 803   (let ((num (hexl-octal-string-to-integer (read-string "Octal Number: "))))
 804     (if (< num 0)
 805         (error "Decimal number out of range")
 806       (hexl-insert-multibyte-char num arg))))
 807
 808 (defun hexl-follow-ascii (&optional arg)
 809   "Toggle following ASCII in Hexl buffers.
 810 With prefix ARG, turn on following if and only if ARG is positive.
 811 When following is enabled, the ASCII character corresponding to the
 812 element under the point is highlighted.
 813 Customize the variable `hexl-follow-ascii' to disable this feature."
 814   (interactive "P")
 815   (let ((on-p (if arg
 816                   (> (prefix-numeric-value arg) 0)
 817                (not hexl-ascii-overlay))))
 818
 819     (if on-p
 820       ;; turn it on
 821       (if (not hexl-ascii-overlay)
 822           (progn
 823             (setq hexl-ascii-overlay (make-overlay 1 1)
 824                   hexl-follow-ascii t)
 825             (overlay-put hexl-ascii-overlay 'face 'highlight)
 826             (add-hook 'post-command-hook 'hexl-follow-ascii-find nil t)))
 827       ;; turn it off
 828       (if hexl-ascii-overlay
 829           (progn
 830             (delete-overlay hexl-ascii-overlay)
 831             (setq hexl-ascii-overlay nil
 832                   hexl-follow-ascii nil)
 833             (remove-hook 'post-command-hook 'hexl-follow-ascii-find t)
 834             )))))
 835
 836 (defun hexl-follow-ascii-find ()
 837   "Find and highlight the ASCII element corresponding to current point."
 838   (let ((pos (+ 51
 839                 (- (point) (current-column))
 840                 (mod (hexl-current-address) 16))))
 841     (move-overlay hexl-ascii-overlay pos (1+ pos))
 842     ))
 843
 844 ;; startup stuff.
 845
 846 (if hexl-mode-map
 847     nil
 848   (setq hexl-mode-map (make-keymap))
 849   ;; Make all self-inserting keys go through hexl-self-insert-command,
 850   ;; because we need to convert them to unibyte characters before
 851   ;; inserting them into the buffer.
 852   (substitute-key-definition 'self-insert-command 'hexl-self-insert-command
 853                              hexl-mode-map (current-global-map))
 854
 855   (define-key hexl-mode-map [left] 'hexl-backward-char)
 856   (define-key hexl-mode-map [right] 'hexl-forward-char)
 857   (define-key hexl-mode-map [up] 'hexl-previous-line)
 858   (define-key hexl-mode-map [down] 'hexl-next-line)
 859   (define-key hexl-mode-map [M-left] 'hexl-backward-short)
 860   (define-key hexl-mode-map [M-right] 'hexl-forward-short)
 861   (define-key hexl-mode-map [next] 'hexl-scroll-up)
 862   (define-key hexl-mode-map [prior] 'hexl-scroll-down)
 863   (define-key hexl-mode-map [home] 'hexl-beginning-of-line)
 864   (define-key hexl-mode-map [end] 'hexl-end-of-line)
 865   (define-key hexl-mode-map [C-home] 'hexl-beginning-of-buffer)
 866   (define-key hexl-mode-map [C-end] 'hexl-end-of-buffer)
 867   (define-key hexl-mode-map [deletechar] 'undefined)
 868   (define-key hexl-mode-map [deleteline] 'undefined)
 869   (define-key hexl-mode-map [insertline] 'undefined)
 870   (define-key hexl-mode-map [S-delete] 'undefined)
 871   (define-key hexl-mode-map "\177" 'undefined)
 872
 873   (define-key hexl-mode-map "\C-a" 'hexl-beginning-of-line)
 874   (define-key hexl-mode-map "\C-b" 'hexl-backward-char)
 875   (define-key hexl-mode-map "\C-d" 'undefined)
 876   (define-key hexl-mode-map "\C-e" 'hexl-end-of-line)
 877   (define-key hexl-mode-map "\C-f" 'hexl-forward-char)
 878
 879   (if (not (eq (key-binding (char-to-string help-char)) 'help-command))
 880       (define-key hexl-mode-map (char-to-string help-char) 'undefined))
 881
 882   (define-key hexl-mode-map "\C-k" 'undefined)
 883   (define-key hexl-mode-map "\C-n" 'hexl-next-line)
 884   (define-key hexl-mode-map "\C-o" 'undefined)
 885   (define-key hexl-mode-map "\C-p" 'hexl-previous-line)
 886   (define-key hexl-mode-map "\C-q" 'hexl-quoted-insert)
 887   (define-key hexl-mode-map "\C-t" 'undefined)
 888   (define-key hexl-mode-map "\C-v" 'hexl-scroll-up)
 889   (define-key hexl-mode-map "\C-w" 'undefined)
 890   (define-key hexl-mode-map "\C-y" 'undefined)
 891
 892   (fset 'hexl-ESC-prefix (copy-keymap 'ESC-prefix))
 893   (define-key hexl-mode-map "\e" 'hexl-ESC-prefix)
 894   (define-key hexl-mode-map "\e\C-a" 'hexl-beginning-of-512b-page)
 895   (define-key hexl-mode-map "\e\C-b" 'hexl-backward-short)
 896   (define-key hexl-mode-map "\e\C-d" 'hexl-insert-decimal-char)
 897   (define-key hexl-mode-map "\e\C-e" 'hexl-end-of-512b-page)
 898   (define-key hexl-mode-map "\e\C-f" 'hexl-forward-short)
 899   (define-key hexl-mode-map "\e\C-i" 'undefined)
 900   (define-key hexl-mode-map "\e\C-j" 'undefined)
 901   (define-key hexl-mode-map "\e\C-k" 'undefined)
 902   (define-key hexl-mode-map "\e\C-o" 'hexl-insert-octal-char)
 903   (define-key hexl-mode-map "\e\C-q" 'undefined)
 904   (define-key hexl-mode-map "\e\C-t" 'undefined)
 905   (define-key hexl-mode-map "\e\C-x" 'hexl-insert-hex-char)
 906   (define-key hexl-mode-map "\eb" 'hexl-backward-word)
 907   (define-key hexl-mode-map "\ec" 'undefined)
 908   (define-key hexl-mode-map "\ed" 'undefined)
 909   (define-key hexl-mode-map "\ef" 'hexl-forward-word)
 910   (define-key hexl-mode-map "\eg" 'hexl-goto-hex-address)
 911   (define-key hexl-mode-map "\ei" 'undefined)
 912   (define-key hexl-mode-map "\ej" 'hexl-goto-address)
 913   (define-key hexl-mode-map "\ek" 'undefined)
 914   (define-key hexl-mode-map "\el" 'undefined)
 915   (define-key hexl-mode-map "\eq" 'undefined)
 916   (define-key hexl-mode-map "\es" 'undefined)
 917   (define-key hexl-mode-map "\et" 'undefined)
 918   (define-key hexl-mode-map "\eu" 'undefined)
 919   (define-key hexl-mode-map "\ev" 'hexl-scroll-down)
 920   (define-key hexl-mode-map "\ey" 'undefined)
 921   (define-key hexl-mode-map "\ez" 'undefined)
 922   (define-key hexl-mode-map "\e<" 'hexl-beginning-of-buffer)
 923   (define-key hexl-mode-map "\e>" 'hexl-end-of-buffer)
 924
 925   (fset 'hexl-C-c-prefix (copy-keymap mode-specific-map))
 926   (define-key hexl-mode-map "\C-c" 'hexl-C-c-prefix)
 927   (define-key hexl-mode-map "\C-c\C-c" 'hexl-mode-exit)
 928
 929   (fset 'hexl-C-x-prefix (copy-keymap 'Control-X-prefix))
 930   (define-key hexl-mode-map "\C-x" 'hexl-C-x-prefix)
 931   (define-key hexl-mode-map "\C-x[" 'hexl-beginning-of-1k-page)
 932   (define-key hexl-mode-map "\C-x]" 'hexl-end-of-1k-page)
 933   (define-key hexl-mode-map "\C-x\C-p" 'undefined)
 934   (define-key hexl-mode-map "\C-x\C-s" 'hexl-save-buffer)
 935   (define-key hexl-mode-map "\C-x\C-t" 'undefined))
 936
 937 (provide 'hexl)
 938
 939 ;;; hexl.el ends here