Function: enable-flow-control

enable-flow-control is an autoloaded, interactive and byte-compiled function defined in flow-ctrl.el.gz.

Signature

(enable-flow-control &optional ARGUMENT)

Documentation

Toggle flow control handling.

When handling is enabled, user can type C-s as C-\, and C-q as C-^. With arg, enable flow control mode if arg is positive, otherwise disable.

Probably introduced at or before Emacs version 19.20.

Key Bindings

Source Code

;; Defined in /usr/src/emacs/lisp/flow-ctrl.el.gz
;;;###autoload
(defun enable-flow-control (&optional argument)
  "Toggle flow control handling.
When handling is enabled, user can type C-s as C-\\, and C-q as C-^.
With arg, enable flow control mode if arg is positive, otherwise disable."
  (interactive "P")
  (if (if argument
	  ;; Argument means enable if arg is positive.
	  (<= (prefix-numeric-value argument) 0)
	;; No arg means toggle.
	(nth 1 (current-input-mode)))
      (progn
	;; Turn flow control off, and stop exchanging chars.
	(set-input-mode t nil (nth 2 (current-input-mode)))
        (when keyboard-translate-table
          (aset keyboard-translate-table flow-control-c-s-replacement nil)
          (aset keyboard-translate-table ?\^s nil)
          (aset keyboard-translate-table flow-control-c-q-replacement nil)
          (aset keyboard-translate-table ?\^q nil)))
    ;; Turn flow control on.
    ;; Tell emacs to pass C-s and C-q to OS.
    (set-input-mode nil t (nth 2 (current-input-mode)))
    ;; Initialize translate table, saving previous mappings, if any.
    (cond ((null keyboard-translate-table)
	   (setq keyboard-translate-table
		 (make-char-table 'keyboard-translate-table nil)))
	  ((char-table-p keyboard-translate-table)
	   (setq keyboard-translate-table
		 (copy-sequence keyboard-translate-table)))
	  (t
	   (let ((the-table (make-char-table 'keyboard-translate-table nil)))
	     (let ((i 0)
		   (j (length keyboard-translate-table)))
	       (while (< i j)
		 (aset the-table i (elt keyboard-translate-table i))
		 (setq i (1+ i))))
	     (setq keyboard-translate-table the-table))))
    ;; Swap C-s and C-\
    (aset keyboard-translate-table flow-control-c-s-replacement ?\^s)
    (aset keyboard-translate-table ?\^s flow-control-c-s-replacement)
    ;; Swap C-q and C-^
    (aset keyboard-translate-table flow-control-c-q-replacement ?\^q)
    (aset keyboard-translate-table ?\^q flow-control-c-q-replacement)
    (message "XON/XOFF adjustment for %s: use %s for C-s, and use %s for C-q"
	     (getenv "TERM")
	     (single-key-description flow-control-c-s-replacement)
	     (single-key-description flow-control-c-q-replacement))
    (sleep-for 2)))			; Give user a chance to see message.