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'.
33Element 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
73