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cbreak, nocbreak, echo, noecho, halfdelay, intrflush, keypad, meta,

 

NAME

        cbreak, nocbreak, echo, noecho, halfdelay, intrflush, keypad, 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-processing (interrupt and flow control charac‐
        ters 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;  therefore, a program should call cbreak or nocbreak explic‐
        itly.  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 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 avail‐
        able to the program.  However, after blocking for tenths tenths of sec‐
        onds, 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 argument is ignored.
 
        The keypad option enables the keypad of the user’s  terminal.   If  en‐
        abled (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 func‐
        tion keys specially and the program has to  interpret  the  escape  se‐
        quences  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  in‐
        put  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  equiva‐
        lent, 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 termi‐
        nal 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 similar to cbreak mode, in that characters typed are  imme‐
        diately  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 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 periodically while updating the screen.  If input  is  found,
        and  it is coming from a tty, the current update is postponed until re     
        fresh or doupdate is called again.  This allows faster response to com‐
        mands  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 descrip‐
        tions.
 
        X/Open does not define any error conditions.  In  this  implementation,
        functions  with  a window parameter will return an error if it is null.
        Any function will also return an error if the terminal was not initial‐
        ized.  Also,
 
               halfdelay
                    returns  an  error  if  its  parameter is outside the range
                    1..255.
 

PORTABILITY

        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 pro‐
        gram remains in cooked mode.
 

NOTES

        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)
 
                                                                curs_inopts(3X)
 

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