NetBSD/share/man/man9/cons.9

.\"	$NetBSD: cons.9,v 1.12 2003/04/01 16:59:45 wiz Exp $
.\"
.\" 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 April 1, 2003
.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
.Fd #include \*[Lt]dev/cons.h\*[Gt]
.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 current console device.
The console must be initialized before these functions can be used.
.Pp
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.
.Pp
The following is a brief description of each function:
.Bl -tag -width "cngetsn()"
.It 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.
.It Fn cnflush
Waits for all pending output to finish.
.It Fn cngetc
Poll (busy wait) for a 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.
.It 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.
\*[Lt]Backspace\*[Gt] key works as expected.
\*[Lt]@\*[Gt] or \*[Lt]CTRL\*[Gt]-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.
.It Fn cnhalt
Terminates the console device (i.e. cleanly shuts down the console hardware.)
.It 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.
.It 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 \*[Lt]Enter\*[Gt] key is pressed:
.Pp
.Bd -literal -compact
int c;

cnpollc(1);
for(;;) {
	c = cngetc();
	if ((c == '\\r' || (c == '\\n')) {
		printf("\\n");
		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