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 the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Commentary:
  27
  28 ;;; Code:
  29
  30 (defvar led-state (make-vector 5 nil)
  31    "The internal state of the LEDs.  Choices are nil, t, `flash.
  32 Element 0 is not used.")
  33
  34 (defun led-flash (l)
  35   "Flash LED l."
  36   (aset led-state l 'flash)
  37   (led-update))
  38
  39 (defun led-off (&optional l)
  40   "Turn off vt100 led number L.  With no argument, turn them all off."
  41   (interactive "P")
  42   (if l
  43       (aset led-state (prefix-numeric-value l) nil)
  44     (fillarray led-state nil))
  45   (led-update))
  46
  47 (defun led-on (l)
  48   "Turn on LED l."
  49   (aset led-state l t)
  50   (led-update))
  51
  52 (defun led-update ()
  53   "Update the terminal's LEDs to reflect the internal state."
  54   (let ((f "\e[?0")                     ; String to flash.
  55         (o "\e[0")                      ; String for steady on.
  56         (l 1))                          ; Current LED number.
  57     (while (/= l 5)
  58       (let ((s (aref led-state l)))
  59         (cond
  60          ((eq s 'flash)
  61           (setq f (concat f ";" (int-to-string l))))
  62          (s
  63           (setq o (concat o ";" (int-to-string l))))))
  64       (setq l (1+ l)))
  65     (setq o (concat o "q" f "t"))
  66     (send-string-to-terminal o)))
  67
  68 (provide 'vt100-led)
  69
  70 ;;; vt100-led.el ends here