79 lines
4.1 KiB
HTML
79 lines
4.1 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<meta name="Copyright" content="Copyright (c) 2006 by IBM Corporation">
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<title>Software Clock APIs</title>
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<body>
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<script language="Javascript" src="../rzahg/synch.js" type="text/javascript">
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<h2>Software Clock APIs</h2>
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<p>The Software Clock APIs are:</p>
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<!-- ***** NOTE ***** Do not manually update text or links in this section. -->
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<!--***************API BEGIN PASTE***************-->
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<ul>
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<li><A HREF="qp0zadjtime.htm">Qp0zAdjTime()</A> (Adjust Software Clock) makes small adjustments to the software clock, either slowing it down or speeding it up by the time specified in the delta parameter.</li>
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<li><A HREF="qp0zgettime.htm">Qp0zGetTimeofDay()</A> (Get Current Software Clock Time) retrieves the current software clock time and places it in the timeval structure pointed to by tp.</li>
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<li><A HREF="qp0zsettime.htm">Qp0zSetTimeofDay()</A> (Set Software Clock) sets the software clock to the time contained in the timeval structure pointed to by tp.</li>
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</ul>
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<!--***************API END PASTE***************-->
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<p><strong>Note:</strong> These functions use header (include) files from the
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library QSYSINC, which is optionally installable. Make sure QSYSINC is
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installed on your system before using any of the functions. See
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<a href="unix13.htm">Header Files for UNIX-Type Functions</a> for the file and member
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name of each header file.</p>
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<p>The Software Clock is a system facility that determines the current
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Universal Coordinated Time (UTC) in seconds and microseconds since 1 January
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1970, 00:00:00 (epoch-1970). The current time is determined by keeping an
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internal 'time-delta', which is an offset from the system clock. When <strong>
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Qp0zGetTimeofDay()</strong> is called to retrieve the software clock time, the
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time returned is calculated by taking the current system time, subtracting the
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QUTCOFFSET system value, then adding the internal time-delta.</p>
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<p>The <strong>Qp0zSettTmeofD</strong><strong>ay()</strong> API sets or changes
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the time-delta, without affecting the system clock or the QUTCOFFSET system
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value. The <strong>Qp0zAdjtime()</strong> API slowly changes the time-delta,
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without affecting the system clock either. Adjustments are made at a rate of
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approximately 1 second of adjustment for every 100 seconds of elapsed time.</p>
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<p>System components do not base their timestamps on the software clock,
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but use the system clock instead. The software clock will be removed in a
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future release and its use is discouraged.</p>
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<hr>
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<center>
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<table cellpadding="2" cellspacing="2">
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<tr align="center">
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<td valign="middle" align="center"><a href="#Top_Of_Page">Top</a> | <a href=
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"unix.htm">UNIX-Type APIs</a> | <a href="aplist.htm">APIs by category</a></td>
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</tr>
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</table>
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</center>
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</body>
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</html>
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