NAME
cnbell,
cnflush,
cngetc,
cngetsn,
cnhalt,
cnpollc,
cnputc —
console access interface
SYNOPSIS
#include <dev/cons.h>
void
cnbell(
u_int
pitch,
u_int period,
u_int volume);
void
cnflush(
void);
int
cngetc(
void);
int
cngetsn(
char
*cp,
int size);
void
cnhalt(
void);
void
cnpollc(
int
on);
void
cnputc(
int
c);
DESCRIPTION
These functions operate over the current console device. The console must be
initialized before these functions can be used.
Console input polling functions
cngetc(),
cngetsn() and
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
tty(4)
facilities.
The following is a brief description of each function:
-
-
- cnbell()
- Ring a bell at appropriate pitch, for
duration of period milliseconds at given
volume. Note that the volume
value is ignored commonly.
-
-
- cnflush()
- Waits for all pending output to finish.
-
-
- cngetc()
- Poll (busy wait) for an input and return the input key.
Returns 0 if there is no console input device. cnpollc()
must be called before cngetc() could
be used. cngetc() should be used during kernel startup
only.
-
-
- cngetsn()
- Read one line of user input, stop reading once the newline
key is input. Input is echoed back. This uses cnpollc()
and cngetc(). Number of read characters is
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 cngetsn()
discard input read so far, print newline and wait for next input.
cngetsn() returns number of characters actually read,
excluding the final newline. cp is
not zero-ended before return.
cngetsn() should be used during kernel startup
only.
-
-
- cnhalt()
- Terminates the console device (i.e. cleanly shuts down the
console hardware.)
-
-
- cnpollc()
- Switch the console driver to polling mode if
on is nonzero, or back to interrupt driven mode if
on is zero. cnpollc() should be
used during kernel startup only.
-
-
- cnputc()
- Console kernel output character routine. Commonly, kernel
code uses printf(9) rather
than using this low-level interface.
EXAMPLES
This waits until a <Enter> key is pressed:
int c;
cnpollc(1);
for(;;) {
c = cngetc();
if ((c == '\r' || (c == '\n')) {
printf("\n");
break;
}
}
cnpollc(0);
SEE ALSO
pckbd(4),
pcppi(4),
tty(4),
wscons(4),
wskbd(4),
printf(9),
spl(9),
wscons(9)