curs_inopts(3curses) curs_inopts(3curses)
NAME
curs_inopts: cbreak, nocbreak, echo, noecho, halfdelay,
intrflush, keypad, meta, nodelay, notimeout, raw, noraw,
noqiflush, qiflush, timeout, wtimeout, typeahead - curses
terminal input option control routines
SYNOPSIS
cc [flag . . .] file -lcurses [library . . .]
#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 characters 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 overrides raw. [See curs_getch(3curses) for
a discussion of how these routines interact with echo and
noecho.]
Copyright 1994 Novell, Inc. Page 1
curs_inopts(3curses) curs_inopts(3curses)
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(3curses)
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 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). 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.
Copyright 1994 Novell, Inc. Page 2
curs_inopts(3curses) curs_inopts(3curses)
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.
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 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.
The timeout and wtimeout routines set blocking or non-blocking
read for a given window. If delay is negative, blocking read
is used (that is, waits indefinitely for input). If delay is
zero, then non-blocking read is used (that is, 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.
Copyright 1994 Novell, Inc. Page 3
curs_inopts(3curses) curs_inopts(3curses)
Return Values
All routines that return an integer return ERR upon failure
and an integer value other than ERR upon successful
completion, unless otherwise noted in the preceding routine
descriptions.
REFERENCES
curses(3curses), curs_getch(3curses), curs_initscr(3curses),
termio(7)
NOTICES
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.
Copyright 1994 Novell, Inc. Page 4