Copyright (c) 2001 The NetBSD Foundation, Inc.
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. All advertising materials mentioning features or use of this software
must display the following acknowledgement:
This product includes software developed by the NetBSD
Foundation, Inc. and its contributors.
4. Neither the name of The NetBSD Foundation nor the names of its
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
.Dd June 2, 2001 .Dt CONS 9 .Os .Sh NAME .Nm cnbell , .Nm cngetc , .Nm cngetsn , .Nm cnpollc , .Nm cnputc .Nd console access interface .Sh SYNOPSIS .Fd #include <dev/cons.h> .Ft void .Fn cnbell "u_int pitch" "u_int period" "u_int volume" .Ft int .Fn cngetc "void" .Ft int .Fn cngetsn "char *cp" "int size" .Ft void .Fn cnpollc "int on" .Ft void .Fn cnputc "int c" .Sh DESCRIPTION These functions operate over current console device. The console has to be initialized first, before these functions could be used.
p Console input polling functions .Fn cngetc , .Fn cngetsn and .Fn cnpollc are only to be used during initial system boot, e.g. when asking for root and dump device or to get necessary user input within mountroothooks. Once the system boots, user input is read via standard .Xr tty 4 facilities.
p
The following is a brief description of each function:
l -tag -width "cngetsn()" t Fn cnbell Ring a bell at appropriate
.Fa pitch ,
for duration of
.Fa period
milliseconds at given
.Fa volume .
Note that the
.Fa volume
value is ignored commonly.
t Fn cngetc Poll (busy wait) for a input and return the input key.
.Fn cnpollc
.Em must
be called before
.Fn cngetc
could be used.
.Fn cngetc
should be used during kernel startup only.
t Fn cngetsn Read one line of user input, stop reading once the newline
key is input. Input is echoed back. This
uses
.Fn cnpollc
and
.Fn cngetc .
Number of read characters is
.Fa size
at maximum, user is notified by console bell when the end
of input buffer is reached. <Backspace> key
works as expected. <@> or <CTRL>-u make
.Fn cngetsn
discard input read so far, print newline and
wait for next input.
.Fn cngetsn
returns number of characters actually read, excluding
the final newline.
.Fa cp
is
.Em not
zero-ended before return.
.Fn cngetsn
should be used during kernel startup only.
t Fn cnpollc Switch the console driver to polling mode if
.Fa on
is nonzero, or back to interrupt driven mode if
.Fa on
is zero.
The system priority level has to be raised to splhigh before
he polling mode could be switched on, so that the polled console device would
ot be disturbed by interrupts. The system priority level has to be
estored to previous level once the polling mode is switched back off.
.Fn cnpollc
should be used during kernel startup only.
t Fn cnputc Console kernel output character routine. Commonly, kernel code uses
.Xr printf 9
rather than using this low-level interface.
.El
.Sh EXAMPLES
This waits until a <Enter> key is pressed:
p
d -literal -compact int s, c;
int c;
s = splhigh();
cnpollc(1);
for(;;) {
c = cngetc();
if ((c == '\\r' || (c == '\\n')) {
printf("\\n");
break;
}
}
cnpollc(0);
splx(s);
.Ed
.Sh SEE ALSO
.Xr pckbd 4 ,
.Xr pcppi 4 ,
.Xr tty 4 ,
.Xr wscons 4 ,
.Xr wskbd 4 ,
.Xr printf 9 ,
.Xr spl 9
Indexes created Sun Oct 26 13:09:57 GMT 2025