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


       #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-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.


       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.


       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.


       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


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

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