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 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 2, or (at your option)
  15 ;; 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; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28
  29 ;;; Code:
  30
  31 (defvar led-state (make-vector 5 nil)
  32    "The internal state of the LEDs.  Choices are nil, t, `flash'.
  33 Element 0 is not used.")
  34
  35 (defun led-flash (l)
  36   "Flash LED l."
  37   (aset led-state l 'flash)
  38   (led-update))
  39
  40 (defun led-off (&optional l)
  41   "Turn off vt100 led number L.  With no argument, turn them all off."
  42   (interactive "P")
  43   (if l
  44       (aset led-state (prefix-numeric-value l) nil)
  45     (fillarray led-state nil))
  46   (led-update))
  47
  48 (defun led-on (l)
  49   "Turn on LED L."
  50   (aset led-state l t)
  51   (led-update))
  52
  53 (defun led-update ()
  54   "Update the terminal's LEDs to reflect the internal state."
  55   (let ((f "\e[?0")                     ; String to flash.
  56         (o "\e[0")                      ; String for steady on.
  57         (l 1))                          ; Current LED number.
  58     (while (/= l 5)
  59       (let ((s (aref led-state l)))
  60         (cond
  61          ((eq s 'flash)
  62           (setq f (concat f ";" (int-to-string l))))
  63          (s
  64           (setq o (concat o ";" (int-to-string l))))))
  65       (setq l (1+ l)))
  66     (setq o (concat o "q" f "t"))
  67     (send-string-to-terminal o)))
  68
  69 (provide 'vt100-led)
  70
  71 ;;; arch-tag: 346e6480-5e31-4234-aafe-257cea4a36d1
  72 ;;; vt100-led.el ends here