code.delx.au - gnu-emacs/blob - lisp/vt100-led.el

   1 ;;; vt100-led.el --- functions for LED control on VT-100 terminals & clones.
   2
   3 ;; Author: Howard Gayle
   4 ;; Maintainer: FSF
   5
   6 ;; Copyright (C) 1988 Free Software Foundation, Inc.
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Code:
  25
  26 (defvar led-state (make-vector 5 nil)
  27    "The internal state of the LEDs.  Choices are nil, t, `flash.
  28 Element 0 is not used.")
  29
  30 (defun led-flash (l)
  31   "Flash LED l."
  32   (aset led-state l 'flash)
  33   (led-update))
  34
  35 (defun led-off (&optional l)
  36   "Turn off vt100 led number L.  With no argument, turn them all off."
  37   (interactive "P")
  38   (if l
  39       (aset led-state (prefix-numeric-value l) nil)
  40     (fillarray led-state nil))
  41   (led-update))
  42
  43 (defun led-on (l)
  44   "Turn on LED l."
  45   (aset led-state l t)
  46   (led-update))
  47
  48 (defun led-update ()
  49   "Update the terminal's LEDs to reflect the internal state."
  50   (let ((f "\e[?0")                     ; String to flash.
  51         (o "\e[0")                      ; String for steady on.
  52         (l 1))                          ; Current LED number.
  53     (while (/= l 5)
  54       (let ((s (aref led-state l)))
  55         (cond
  56          ((eq s 'flash)
  57           (setq f (concat f ";" (int-to-string l))))
  58          (s
  59           (setq o (concat o ";" (int-to-string l))))))
  60       (setq l (1+ l)))
  61     (setq o (concat o "q" f "t"))
  62     (send-string-to-terminal o)))
  63
  64 (provide 'vt100-led)
  65
  66 ;;; vt100-led.el ends here