curs_inopts(3X) MISCELLANEOUS LIBRARY FUNCTIONS curs_inopts(3X)
NAME
cursinopts: cbreak, nocbreak, echo, noecho, halfdelay,
intrflush, keypad, meta, nodelay, notimeout, raw, noraw,
noqiflush, qiflush, timeout, wtimeout, typeahead - curses
terminal input option control routines
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 notimeout(WINDOW *win, bool bf);
int raw(void);
int noraw(void);
void noqiflush(void);
void qiflush(void);
void timeout(int delay);
void wtimeout(WINDOW *win, int delay);
int typeahead(int fd);
DESCRIPTION
The cbreak and nocbreak routines put the terminal into and
out of cbreak mode, respectively. In this mode, characters
typed by the user are immediately available to the program,
and erase/kill character-processing is not performed. When
out of this mode, the tty driver buffers the typed charac-
ters until a newline or carriage return is typed. Interrupt
and flow control characters are unaffected by this 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 initially getch is in echo
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curs_inopts(3X) MISCELLANEOUS LIBRARY FUNCTIONS curs_inopts(3X)
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 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 KEYLEFT.
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). To force 7 bits to be
returned, invoke meta(win, FALSE). 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 node-
lay 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 inter-
preting 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. With the raw
and noraw routines, the terminal is placed into or out of
raw mode. Raw mode is similar to cbreak mode, in that char-
acters typed are immediately passed through to the user pro-
gram. 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
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curs_inopts(3X) MISCELLANEOUS LIBRARY FUNCTIONS curs_inopts(3X)
behavior of the BREAK key depends on other bits in the tty
driver that are not set by curses. When the noqiflush rou-
tine is used, normal flush of input and output queues asso-
ciated 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. 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). curses 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 failure
and an integer value other than ERR upon successful comple-
tion, unless otherwise noted in the preceding routine
descriptions.
NOTES
The header file <curses.h> automatically includes the header
files <stdio.h> and <unctrl.h>.
Note that echo, noecho, halfdelay, intrflush, meta, nodelay,
notimeout, noqiflush, qiflush, timeout, and wtimeout may be
macros.
SEE ALSO
curses(3X), cursgetch(3X), cursinitscr(3X), termio(7).
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