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 ;; Author: Howard Gayle
   6 ;; Maintainer: FSF
   7 ;; Keywords: hardware
   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
  23 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  24
  25 ;;; Code:
  26
  27 (defvar led-state (make-vector 5 nil)
  28    "The internal state of the LEDs.  Choices are nil, t, `flash.
  29 Element 0 is not used.")
  30
  31 (defun led-flash (l)
  32   "Flash LED l."
  33   (aset led-state l 'flash)
  34   (led-update))
  35
  36 (defun led-off (&optional l)
  37   "Turn off vt100 led number L.  With no argument, turn them all off."
  38   (interactive "P")
  39   (if l
  40       (aset led-state (prefix-numeric-value l) nil)
  41     (fillarray led-state nil))
  42   (led-update))
  43
  44 (defun led-on (l)
  45   "Turn on LED l."
  46   (aset led-state l t)
  47   (led-update))
  48
  49 (defun led-update ()
  50   "Update the terminal's LEDs to reflect the internal state."
  51   (let ((f "\e[?0")                     ; String to flash.
  52         (o "\e[0")                      ; String for steady on.
  53         (l 1))                          ; Current LED number.
  54     (while (/= l 5)
  55       (let ((s (aref led-state l)))
  56         (cond
  57          ((eq s 'flash)
  58           (setq f (concat f ";" (int-to-string l))))
  59          (s
  60           (setq o (concat o ";" (int-to-string l))))))
  61       (setq l (1+ l)))
  62     (setq o (concat o "q" f "t"))
  63     (send-string-to-terminal o)))
  64
  65 (provide 'vt100-led)
  66
  67 ;;; vt100-led.el ends here