125 lines
5.0 KiB
EmacsLisp
125 lines
5.0 KiB
EmacsLisp
;;; flow-ctrl.el --- help for lusers on cu(1) or ttys with wired-in ^S/^Q flow control -*- lexical-binding: t -*-
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;; Copyright (C) 1990-1991, 1994, 2001-2024 Free Software Foundation,
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;; Inc.
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;; Author: Kevin Gallagher
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;; Maintainer: emacs-devel@gnu.org
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;; Adapted-By: ESR
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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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;; Terminals that use XON/XOFF flow control can cause problems with
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;; GNU Emacs users. This file contains Emacs Lisp code that makes it
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;; easy for a user to deal with this problem, when using such a
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;; terminal.
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;;
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;; To invoke these adjustments, a user need only invoke the function
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;; enable-flow-control-on with a list of terminal types in his/her own
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;; init file. As arguments, give it the names of one or more terminal
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;; types in use by that user which require flow control adjustments.
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;; Here's an example:
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;;
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;; (enable-flow-control-on "vt200" "vt300" "vt101" "vt131")
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;; Portability note: This uses (getenv "TERM"), and therefore probably
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;; won't work outside of UNIX-like environments.
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;;; Code:
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(defvar flow-control-c-s-replacement ?\034
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"Character that replaces C-s, when flow control handling is enabled.")
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(defvar flow-control-c-q-replacement ?\036
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"Character that replaces C-q, when flow control handling is enabled.")
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(put 'keyboard-translate-table 'char-table-extra-slots 0)
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;;;###autoload
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(defun enable-flow-control (&optional argument)
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"Toggle flow control handling.
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When handling is enabled, user can type C-s as C-\\, and C-q as C-^.
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With arg, enable flow control mode if arg is positive, otherwise disable."
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(interactive "P")
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(if (if argument
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;; Argument means enable if arg is positive.
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(<= (prefix-numeric-value argument) 0)
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;; No arg means toggle.
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(nth 1 (current-input-mode)))
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(progn
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;; Turn flow control off, and stop exchanging chars.
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(set-input-mode t nil (nth 2 (current-input-mode)))
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(when keyboard-translate-table
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(aset keyboard-translate-table flow-control-c-s-replacement nil)
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(aset keyboard-translate-table ?\^s nil)
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(aset keyboard-translate-table flow-control-c-q-replacement nil)
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(aset keyboard-translate-table ?\^q nil)))
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;; Turn flow control on.
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;; Tell emacs to pass C-s and C-q to OS.
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(set-input-mode nil t (nth 2 (current-input-mode)))
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;; Initialize translate table, saving previous mappings, if any.
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(cond ((null keyboard-translate-table)
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(setq keyboard-translate-table
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(make-char-table 'keyboard-translate-table nil)))
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((char-table-p keyboard-translate-table)
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(setq keyboard-translate-table
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(copy-sequence keyboard-translate-table)))
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(t
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(let ((the-table (make-char-table 'keyboard-translate-table nil)))
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(let ((i 0)
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(j (length keyboard-translate-table)))
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(while (< i j)
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(aset the-table i (elt keyboard-translate-table i))
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(setq i (1+ i))))
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(setq keyboard-translate-table the-table))))
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;; Swap C-s and C-\
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(aset keyboard-translate-table flow-control-c-s-replacement ?\^s)
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(aset keyboard-translate-table ?\^s flow-control-c-s-replacement)
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;; Swap C-q and C-^
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(aset keyboard-translate-table flow-control-c-q-replacement ?\^q)
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(aset keyboard-translate-table ?\^q flow-control-c-q-replacement)
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(message "XON/XOFF adjustment for %s: use %s for C-s, and use %s for C-q"
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(getenv "TERM")
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(single-key-description flow-control-c-s-replacement)
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(single-key-description flow-control-c-q-replacement))
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(sleep-for 2))) ; Give user a chance to see message.
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;;;###autoload
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(defun enable-flow-control-on (&rest losing-terminal-types)
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"Enable flow control if using one of a specified set of terminal types.
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Use `(enable-flow-control-on \"vt100\" \"h19\")' to enable flow control
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on VT-100 and H19 terminals. When flow control is enabled,
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you must type C-\\ to get the effect of a C-s, and type C-^
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to get the effect of a C-q."
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(let ((term (getenv "TERM"))
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hyphend)
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;; Look for TERM in LOSING-TERMINAL-TYPES.
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;; If we don't find it literally, try stripping off words
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;; from the end, one by one.
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(while (and term (not (member term losing-terminal-types)))
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;; Strip off last hyphen and what follows, then try again.
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(if (setq hyphend (string-match "[-_][^-_]+$" term))
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(setq term (substring term 0 hyphend))
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(setq term nil)))
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(if term
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(enable-flow-control))))
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(provide 'flow-ctrl)
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;;; flow-ctrl.el ends here
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