## NAME

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

## SYNOPSIS

           #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);

## DESCRIPTION

           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-process-
           ing  (interrupt  and  flow  control  characters  are unaf-
           fected), 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; therefore, a program should call
           cbreak or nocbreak explicitly.  Most interactive  programs
           using  curses set the cbreak mode.  Note that cbreak over-
           rides 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 ini-
           tially getch is in echo  mode,  so  characters  typed  are
           echoed.  Authors of most interactive programs 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 mode.

           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, giving 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  argu-
           ment is ignored.

           The  keypad option enables the keypad of the user's termi-
           nal.  If enabled (bf is TRUE), the user can press a  func-
           tion  key (such as an arrow key) and wgetch returns a sin-
           gle 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 key-
           pad 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  equiva-
           lent,  under  POSIX, to setting the CS8 flag on the termi-
           nal.  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 notime-
           out(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 similar 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 curses.

           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 waiting).  If delay
           is  positive, then read blocks for delay milliseconds, and
           returns ERR if there is still no input.  Hence, these rou-
           tines  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  periodically  while  updating  the
           screen.   If  input is found, and it is coming from a tty,
           the current 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.

## RETURN VALUE

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

## PORTABILITY

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

           The  ncurses  library obeys the XPG4 standard and the his-
           torical 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  portabil-
           ity,  set echo or noecho explicitly just after initializa-
           tion, even if your program remains in cooked mode.

## NOTES

           Note that echo, noecho, halfdelay, intrflush, meta,  node-
           lay,  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.

## SEE ALSO

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