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RedHat 9 (Linux i386) - man page for typeahead (redhat section 3X)

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curs_inopts(3X) 								  curs_inopts(3X)

       cbreak,	nocbreak,  echo,  noecho, halfdelay, intrflush, keypad, meta, nodelay, notimeout,
       raw, noraw, noqiflush, qiflush, timeout, wtimeout, typeahead - curses input options

       #include <curses.h>

       int cbreak(void);
       int nocbreak(void);
       int echo(void);
       int noecho(void);
       int halfdelay(int tenths);
       int intrflush(WINDOW *win, bool bf);
       int keypad(WINDOW *win, bool bf);
       int meta(WINDOW *win, bool bf);
       int nodelay(WINDOW *win, bool bf);
       int raw(void);
       int noraw(void);
       void noqiflush(void);
       void qiflush(void);
       int notimeout(WINDOW *win, bool bf);
       void timeout(int delay);
       void wtimeout(WINDOW *win, int delay);
       int typeahead(int fd);

       Normally, the tty driver buffers typed characters until a newline or  carriage  return  is
       typed.	The  cbreak  routine  disables line buffering and erase/kill character-processing
       (interrupt and flow control characters are unaffected), making  characters  typed  by  the
       user  immediately  available to the program.  The nocbreak routine returns the terminal to
       normal (cooked) mode.

       Initially the terminal may or may not be in cbreak mode, as the mode is inherited;  there-
       fore,  a  program  should  call	cbreak or nocbreak explicitly.	Most interactive programs
       using curses set the cbreak mode.  Note that cbreak overrides  raw.   [See  curs_getch(3X)
       for a discussion of how these routines interact with echo and noecho.]

       The  echo  and  noecho routines control whether characters typed by the user are echoed by
       getch as they are typed.  Echoing by the tty driver  is	always	disabled,  but	initially
       getch  is  in echo mode, so characters typed are echoed.  Authors of most interactive pro-
       grams prefer to do their own echoing in a controlled area of the screen, or not to echo at
       all,  so  they disable echoing by calling noecho.  [See curs_getch(3X) for a discussion of
       how these routines interact with cbreak and nocbreak.]

       The halfdelay routine is used for half-delay mode, which is similar to cbreak mode in that
       characters  typed  by  the  user are immediately available to the program.  However, after
       blocking for tenths tenths of seconds, ERR is returned if nothing  has  been  typed.   The
       value  of  tenths  must	be  a number between 1 and 255.  Use nocbreak to leave half-delay

       If the intrflush option is enabled, (bf is TRUE), when an interrupt key is pressed on  the
       keyboard (interrupt, break, quit) all output in the tty driver queue will be flushed, giv-
       ing the effect of faster response to the interrupt, but causing curses to have  the  wrong
       idea  of  what  is on the screen.  Disabling (bf is FALSE), the option prevents the flush.
       The default for the option is inherited from the tty driver settings.  The window argument
       is ignored.

       The keypad option enables the keypad of the user's terminal.  If enabled (bf is TRUE), the
       user can press a function key (such as an arrow key) and wgetch	returns  a  single  value
       representing the function key, as in KEY_LEFT.  If disabled (bf is FALSE), curses does not
       treat function keys specially and the  program  has  to	interpret  the	escape	sequences
       itself.	 If  the keypad in the terminal can be turned on (made to transmit) and off (made
       to work locally), turning on this option causes the terminal keypad to be turned  on  when
       wgetch is called.  The default value for keypad is false.

       Initially,  whether  the  terminal returns 7 or 8 significant bits on input depends on the
       control mode of the tty driver [see termio(7)].	To force 8 bits to  be	returned,  invoke
       meta(win, TRUE); this is equivalent, under POSIX, to setting the CS8 flag on the terminal.
       To force 7 bits to be returned, invoke meta(win, FALSE); this is equivalent, under  POSIX,
       to setting the CS7 flag on the terminal.  The window argument, win, is always ignored.  If
       the terminfo capabilities smm (meta_on) and rmm (meta_off) are defined for  the	terminal,
       smm  is sent to the terminal when meta(win, TRUE) is called and rmm is sent when meta(win,
       FALSE) is called.

       The nodelay option causes getch to be a non-blocking call.  If no input	is  ready,  getch
       returns ERR.  If disabled (bf is FALSE), getch waits until a key is pressed.

       While  interpreting  an	input  escape sequence, wgetch sets a timer while waiting for the
       next character.	If notimeout(win, TRUE) is called, then wgetch does not set a timer.  The
       purpose	of the timeout is to differentiate between sequences received from a function key
       and those typed by a user.

       The raw and noraw routines place the terminal into or out of raw mode.  Raw mode is  simi-
       lar  to	cbreak	mode, in that characters typed are immediately passed through to the user
       program.  The differences are that in raw mode, the interrupt,  quit,  suspend,	and  flow
       control	characters  are all passed through uninterpreted, instead of generating a signal.
       The behavior of the BREAK key depends on other bits in the tty driver that are not set  by

       When  the  noqiflush  routine  is used, normal flush of input and output queues associated
       with the INTR, QUIT and SUSP characters will not be done [see termio(7)].  When qiflush is
       called,	the  queues will be flushed when these control characters are read.  You may want
       to call noqiflush() in a signal handler if you want  output  to	continue  as  though  the
       interrupt had not occurred, after the handler exits.

       The  timeout  and  wtimeout routines set blocking or non-blocking read for a given window.
       If delay is negative, blocking read is used (i.e.,  waits  indefinitely	for  input).   If
       delay is zero, then non-blocking read is used (i.e., read returns ERR if no input is wait-
       ing).  If delay is positive, then read blocks for delay milliseconds, and returns  ERR  if
       there is still no input.  Hence, these routines provide the same functionality as nodelay,
       plus the additional capability of being able to block for only delay  milliseconds  (where
       delay is positive).

       The  curses  library does ``line-breakout optimization'' by looking for typeahead periodi-
       cally while updating the screen.  If input is found, and it is coming from a tty, the cur-
       rent  update  is  postponed until refresh or doupdate is called again.  This allows faster
       response to commands typed in  advance.	 Normally,  the  input	FILE  pointer  passed  to
       newterm,  or  stdin  in	the case that initscr was used, will be used to do this typeahead
       checking.  The typeahead routine specifies that the file descriptor fd is to  be  used  to
       check for typeahead instead.  If fd is -1, then no typeahead checking is done.

       All  routines  that  return an integer return ERR upon failure and OK (SVr4 specifies only
       "an integer value other than ERR") upon successful completion, unless otherwise	noted  in
       the preceding routine descriptions.

       These functions are described in the XSI Curses standard, Issue 4.

       The ncurses library obeys the XPG4 standard and the historical practice of the AT&T curses
       implementations, in that the echo bit is cleared  when  curses  initializes  the  terminal
       state.  BSD curses differed from this slightly; it left the echo bit on at initialization,
       but the BSD raw call turned it off as a side-effect.  For best portability,  set  echo  or
       noecho explicitly just after initialization, even if your program remains in cooked mode.

       Note  that  echo,  noecho,  halfdelay,  intrflush,  meta,  nodelay,  notimeout, noqiflush,
       qiflush, timeout, and wtimeout may be macros.

       The noraw and nocbreak calls follow historical practice in that they attempt to restore to
       normal  (`cooked')  mode  from  raw  and  cbreak modes respectively.  Mixing raw/noraw and
       cbreak/nocbreak calls leads to tty driver control states  that  are  hard  to  predict  or
       understand; it is not recommended.

       curses(3X), curs_getch(3X), curs_initscr(3X), termio(7)

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