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.
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 8, 2010 .Dt CONS 9 .Os .Sh NAME .Nm cnbell , .Nm cnflush , .Nm cngetc , .Nm cngetsn , .Nm cnhalt , .Nm cnpollc , .Nm cnputc .Nd console access interface .Sh SYNOPSIS n dev/cons.h .Ft void .Fn cnbell "u_int pitch" "u_int period" "u_int volume" .Ft void .Fn cnflush "void" .Ft int .Fn cngetc "void" .Ft int .Fn cngetsn "char *cp" "int size" .Ft void .Fn cnhalt "void" .Ft void .Fn cnpollc "int on" .Ft void .Fn cnputc "int c" .Sh DESCRIPTION These functions operate over the current console device. The console must be initialized before these functions can 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 cnflush Waits for all pending output to finish. t Fn cngetc Poll (busy wait) for an input and return the input key. Returns 0 if there is no console input device. .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 cnhalt Terminates the console device (i.e. cleanly shuts down the console hardware.) 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. .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 -offset indent int c; cnpollc(1); for(;;) { c = cngetc(); if ((c == '\er' || (c == '\en')) { printf("\en"); break; } } cnpollc(0); .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 , .Xr wscons 9
Indexes created Sat Sep 20 22:09:52 GMT 2025