lisp/vt100-led.el

   1 ;;; vt100-led.el --- functions for LED control on VT-100 terminals & clones
   2
   3 ;; Copyright (C) 1988, 2001, 2002, 2003, 2004, 2005,
   4 ;;   2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
   5
   6 ;; Author: Howard Gayle
   7 ;; Maintainer: FSF
   8 ;; Keywords: hardware
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;;; Code:
  28
  29 (defvar led-state (make-vector 5 nil)
  30    "The internal state of the LEDs.  Choices are nil, t, `flash'.
  31 Element 0 is not used.")
  32
  33 (defun led-flash (l)
  34   "Flash LED l."
  35   (aset led-state l 'flash)
  36   (led-update))
  37
  38 (defun led-off (&optional l)
  39   "Turn off vt100 led number L.  With no argument, turn them all off."
  40   (interactive "P")
  41   (if l
  42       (aset led-state (prefix-numeric-value l) nil)
  43     (fillarray led-state nil))
  44   (led-update))
  45
  46 (defun led-on (l)
  47   "Turn on LED L."
  48   (aset led-state l t)
  49   (led-update))
  50
  51 (defun led-update ()
  52   "Update the terminal's LEDs to reflect the internal state."
  53   (let ((f "\e[?0")                     ; String to flash.
  54         (o "\e[0")                      ; String for steady on.
  55         (l 1))                          ; Current LED number.
  56     (while (/= l 5)
  57       (let ((s (aref led-state l)))
  58         (cond
  59          ((eq s 'flash)
  60           (setq f (concat f ";" (int-to-string l))))
  61          (s
  62           (setq o (concat o ";" (int-to-string l))))))
  63       (setq l (1+ l)))
  64     (setq o (concat o "q" f "t"))
  65     (send-string-to-terminal o)))
  66
  67 (provide 'vt100-led)
  68
  69 ;;; vt100-led.el ends here