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1 <h2>clock_alarm</h2>
2 <hr>
3 <p>
4 <strong>Function</strong> - Set off an alarm.
5 <h3>SYNOPSIS</h3>
6 <pre>
7 <strong>kern_return_t clock_alarm</strong>
8 <strong>(clock_t</strong> <var>clock_name</var>,
9 <strong>alarm_type_t</strong> <var>alarm_type</var>,
10 <strong>tvalspec_t</strong> <var>alarm_time</var>,
11 <strong>mach_port_t</strong> <var>alarm_reply_port</var><strong>);</strong>
12 </pre>
13 <h3>PARAMETERS</h3>
14 <dl>
15 <p>
16 <dt> <var>clock_name</var>
17 <dd>
18 [in clock-name send right]
19 The name (or control) port for the clock.
20 <p>
21 <dt> <var>alarm_type</var>
22 <dd>
23 [in scalar]
24 How to interpret the <var>alarm_time</var> value:
25 <dl>
26 <p>
27 <dt> <strong>TIME_RELATIVE</strong>
28 <dd>
29 Interpret the alarm time as relative to the current time.
30 <p>
31 <dt> <strong>TIME_ABSOLUTE</strong>
32 <dd>
33 Interpret the alarm time as an absolute time.
34 </dl>
35 <p>
36 <dt> <var>alarm_time</var>
37 <dd>
38 [in structure]
39 The time when the alarm is to be sent.
40 <p>
41 <dt> <var>alarm_reply_port</var>
42 <dd>
43 [in alarm receive (to be converted to send-once) right]
44 A port into
45 which the alarm message is to be sent.
46 </dl>
47 <h3>DESCRIPTION</h3>
48 <p>
49 The <strong>clock_alarm</strong> function requests that a clock send
50 an alarm message to a
51 specified port at a given future time. The alarm message is specified by the
52 <strong>clock_alarm_reply</strong> server interface.
53 <h3>NOTES</h3>
54 <p>
55 If the specified alarm time is in the past, the alarm message
56 is sent immediately
57 and time-stamped with the current time. Otherwise, the alarm is queued and
58 delivered at the specified alarm time and time-stamped at that time.
59 <p>
60 The alarm will be serviced at the service time nearest the specified
61 alarm time
62 as governed by the current clock alarm resolution.
63 <p>
64 Not all clocks implement this service, but the REALTIME clock must. If the
65 clock does not provide this service, this call is ignored.
66 <h3>RETURN VALUES</h3>
67 <p>
68 Only generic errors apply.
69 <h3>RELATED INFORMATION</h3>
70 <p>
71 Functions:
72 <a href="host_get_clock_service.html"><strong>host_get_clock_service</strong></a>,
73 <a href="clock_get_attributes.html"><strong>clock_get_attributes</strong></a>,
74 <a href="clock_get_time.html"><strong>clock_get_time</strong></a>,
75 <a href="clock_sleep.html"><strong>clock_sleep</strong></a>,
76 <a href="clock_alarm_reply.html"><strong>clock_alarm_reply</strong></a>.
77 <p>
78 Data Structures:
79 <a href="tvalspec.html"><strong>tvalspec</strong></a>.