68 lines
1.9 KiB
EmacsLisp
68 lines
1.9 KiB
EmacsLisp
;;; vt100-led.el --- functions for LED control on VT-100 terminals & clones -*- lexical-binding:t -*-
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;; Copyright (C) 1988, 2001-2020 Free Software Foundation, Inc.
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;; Author: Howard Gayle
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;; Maintainer: emacs-devel@gnu.org
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;; Keywords: hardware
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation, either version 3 of the License, or
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;;; Code:
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(defvar led-state (make-vector 5 nil)
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"The internal state of the LEDs. Choices are nil, t, `flash'.
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Element 0 is not used.")
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(defun led-flash (l)
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"Flash LED l."
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(aset led-state l 'flash)
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(led-update))
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(defun led-off (&optional l)
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"Turn off vt100 led number L. With no argument, turn them all off."
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(interactive "P")
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(if l
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(aset led-state (prefix-numeric-value l) nil)
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(fillarray led-state nil))
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(led-update))
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(defun led-on (l)
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"Turn on LED L."
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(aset led-state l t)
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(led-update))
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(defun led-update ()
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"Update the terminal's LEDs to reflect the internal state."
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(let ((f "\e[?0") ; String to flash.
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(o "\e[0") ; String for steady on.
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(l 1)) ; Current LED number.
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(while (/= l 5)
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(let ((s (aref led-state l)))
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(cond
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((eq s 'flash)
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(setq f (concat f ";" (int-to-string l))))
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(s
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(setq o (concat o ";" (int-to-string l))))))
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(setq l (1+ l)))
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(setq o (concat o "q" f "t"))
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(send-string-to-terminal o)))
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(provide 'vt100-led)
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;;; vt100-led.el ends here
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