lisp/vt100-led.el

   1 ;;; vt100-led.el --- functions for LED control on VT-100 terminals & clones.
   2
   3 ;; Copyright (C) 1988 Free Software Foundation, Inc.
   4
   5 ;; This file is part of GNU Emacs.
   6
   7 ;; GNU Emacs is free software; you can redistribute it and/or modify
   8 ;; it under the terms of the GNU General Public License as published by
   9 ;; the Free Software Foundation; either version 1, or (at your option)
  10 ;; any later version.
  11
  12 ;; GNU Emacs is distributed in the hope that it will be useful,
  13 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 ;; GNU General Public License for more details.
  16
  17 ;; You should have received a copy of the GNU General Public License
  18 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  19 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  20
  21
  22 ;; Written by Howard Gayle.
  23
  24 (defvar led-state (make-vector 5 nil)
  25    "The internal state of the LEDs.  Choices are nil, t, `flash.
  26 Element 0 is not used.")
  27
  28 (defun led-flash (l)
  29   "Flash LED l."
  30   (aset led-state l 'flash)
  31   (led-update))
  32
  33 (defun led-off (&optional l)
  34   "Turn off vt100 led number L.  With no argument, turn them all off."
  35   (interactive "P")
  36   (if l
  37       (aset led-state (prefix-numeric-value l) nil)
  38     (fillarray led-state nil))
  39   (led-update))
  40
  41 (defun led-on (l)
  42   "Turn on LED l."
  43   (aset led-state l t)
  44   (led-update))
  45
  46 (defun led-update ()
  47   "Update the terminal's LEDs to reflect the internal state."
  48   (let ((f "\e[?0")                     ; String to flash.
  49         (o "\e[0")                      ; String for steady on.
  50         (l 1))                          ; Current LED number.
  51     (while (/= l 5)
  52       (let ((s (aref led-state l)))
  53         (cond
  54          ((eq s 'flash)
  55           (setq f (concat f ";" (int-to-string l))))
  56          (s
  57           (setq o (concat o ";" (int-to-string l))))))
  58       (setq l (1+ l)))
  59     (setq o (concat o "q" f "t"))
  60     (send-string-to-terminal o)))
  61
  62 (provide 'vt100-led)
  63
  64 ;;; vt100-led.el ends here