xnu-3789.1.32.tar.gz

[apple/xnu.git] / osfmk / man / host_get_clock_service.html

<h2>host_get_clock_service</h2>
<hr>
<p>
<strong>Function</strong> - Return a send right to a kernel clock's service port.
<h3>SYNOPSIS</h3>
<pre>
<strong>kern_return_t   host_get_clock_service</strong>
                <strong>(host_t</strong>                                    <var>host</var>,
                 <strong>clock_id_t</strong>                                  <var>id</var>,
                 <strong>clock_t</strong>                             <var>clock_name</var><strong>);</strong>
</pre>
<h3>PARAMETERS</h3>
<dl>
<p>
<dt> <var>host</var> 
<dd>
[in host-name send right]
The name (or control) port for the host
owning the clock.
<p>
<dt> <var>id</var> 
<dd>
[in scalar]
The identification of the desired kernel clock.  These values 
are defined in \*L<mach/clock_types.h>\*O.  Although an implementation 
may define additional values, the following values are always defined 
(although only the REALTIME clock is required to be implemented):
<dl>
<p>
<dt> <strong>REALTIME_CLOCK</strong>
<dd>
A moderate resolution clock service that (typically) tracks 
time since the system last boot.
<p>
<dt> <strong>BATTERY_CLOCK</strong>
<dd>
A (typically) low resolution clock (to the second) that
survives power failures or service outages.
<p>
<dt> <strong>HIGHRES_CLOCK</strong>
<dd>
A high resolution clock.
</dl>
<p>
<dt> <var>clock_name</var> 
<dd>
[out clock-name send right]
Name port for the clock.
</dl>
<h3>DESCRIPTION</h3>
<p>
The <strong>host_get_clock_service</strong> function returns a send
right to the name port for a 
kernel clock object.  This right is used to get the time and
resolutions of the 
clock and to set clock alarms.
<h3>RETURN VALUES</h3>
<p>
Only generic errors apply.
<h3>RELATED INFORMATION</h3>
<p>
Functions:
<a href="clock_get_time.html"><strong>clock_get_time</strong></a>,
<a href="clock_get_attributes.html"><strong>clock_get_attributes</strong></a>,
<a href="clock_map_time.html"><strong>clock_map_time</strong></a>,
<a href="clock_sleep.html"><strong>clock_sleep</strong></a>,
<a href="clock_alarm.html"><strong>clock_alarm</strong></a>,
<a href="host_get_clock_control.html"><strong>host_get_clock_control</strong></a>.