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+;;; Help for lusers on cu(1) or terminals with wired-in ^S/^Q flow control
+;;;
+;;; Copyright (C) 1990 Free Software Foundation, Inc.
+;;; Copyright (C) 1991 Kevin Gallagher
+;;; Adapted for Emacs 19 by Eric S. Raymond <eric@snark.thyrsus.com>
+;;;
+;;; GNU Emacs is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY.  No author or distributor accepts
+;;; RESPONSIBILITY TO anyone for the consequences of using it or for
+;;; whether it serves any particular purpose or works at all, unless 
+;;; he says so in writing.  Refer to the GNU Emacs General Public
+;;; License for full details.
+;;;
+;;; Everyone is granted permission to copy, modify and redistribute
+;;; GNU Emacs, but only under the conditions described in the GNU
+;;; Emacs General Public License.  A copy of this license is supposed
+;;; to have been given to you along with GNU Emacs so you can know
+;;; your rights and responsibilities.  It should be in a file named
+;;; COPYING.  Among other things, the Copyright notice and this notice
+;;; must be preserved on all copies.
+;;;
+
+;;;; Terminals that use XON/XOFF flow control can cause problems with
+;;;; GNU Emacs users.  This file contains elisp code that makes it
+;;;; easy for a user to deal with this problem, when using such a
+;;;; terminal. 
+;;;;      
+;;;; To invoke these adjustments, a user need only invoke the function
+;;;; evade-flow-control-on with a list of terminal types in his/her own
+;;;; .emacs file.  As arguments, give it the names of one or more terminal
+;;;; types in use by that user which require flow control adjustments.
+;;;; Here's an example: 
+;;;; 
+;;;;    (evade-flow-control-on "vt200" "vt300" "vt101" "vt131")
+
+;;; Portability note: This uses (getenv "TERM"), and therefore probably
+;;; won't work outside of UNIX-like environments.
+
+(defun evade-flow-control ()
+  "Replace C-s with C-\ and C-q with C-^ and tell emacs to pass C-s
+and C-q characters to OS."
+  (interactive)
+  ;; Tell emacs to pass C-s and C-q to OS.
+  (set-input-mode nil t)
+  ;; Initialize translate table, saving previous mappings, if any.
+  (let ((the-table (make-string 128 0)))
+    (let ((i 0)
+          (j (length keyboard-translate-table)))
+      (while (< i j)
+        (aset the-table i (elt keyboard-translate-table i))
+        (setq i (1+ i)))
+      (while (< i 128)
+        (aset the-table i i)
+        (setq i (1+ i))))
+    (setq keyboard-translate-table the-table))
+  ;; Swap C-s and C-\
+  (aset keyboard-translate-table ?\034 ?\^s)
+  (aset keyboard-translate-table ?\^s ?\034)
+  ;; Swap C-q and C-^
+  (aset keyboard-translate-table ?\036 ?\^q)
+  (aset keyboard-translate-table ?\^q ?\036)
+  (message (concat 
+             "XON/XOFF adjustment for " 
+             (getenv "TERM") 
+             ":  use C-\\ for C-s  and  use C-^ for C-q."))
+  (sleep-for 2)) ; Give user a chance to see message.
+
+(defun memstr= (e s)
+  (cond ((null s) nil)
+        ((string= e (car s)) t)
+        (t (memstr= e (cdr s)))))
+
+;;;###autoload
+(defun evade-flow-control-on (&rest losing-terminal-types)
+  (let ((term (getenv "TERM"))
+        hyphend)
+    ;; Strip off hyphen and what follows
+    (while (setq hyphend (string-match "[-_][^-_]+$" term))
+      (setq term (substring term 0 hyphend)))
+    (and (memstr= term losing-terminal-types) (evade-flow-control)))
+  )
+
+(provide 'flow-ctrl)
+
+;;; flow-ctrl.el ends here
+