331 lines
8.5 KiB
HTML
331 lines
8.5 KiB
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<!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>getitimer()--Get Value for Interval Timer</title>
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<!-- Begin Header Records ========================================== -->
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<!-- Change History: -->
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<!-- UNIX5 SCRIPT J converted by B2H R4.1 (346) (CMS) by V2KEA304 -->
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<!-- at RCHVMW2 on 17 Feb 1999 at 11:05:09 -->
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<!-- Edited by Kersten Feb 02 -->
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<!-- This file has undergone error condition cleanup on 04/30/02 by JET -->
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<link rel="stylesheet" type="text/css" href="../rzahg/ic.css">
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</head>
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<body>
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<!--End Header Records -->
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<!-- Java sync-link -->
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<script type="text/javascript" language="Javascript" src="../rzahg/synch.js">
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</script>
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<a name="Top_Of_Page"></a>
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<h2>getitimer()--Get Value for Interval Timer</h2>
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<div class="box" style="width: 60%;">
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<br>
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Syntax<br>
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<pre>
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#include <sys/time.h>
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int getitimer( int <em>which</em>, struct itimerval <em>*value</em> );
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</pre>
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<br>
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Service Program Name: QP0SSRVI<br>
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<!-- iddvc RMBR -->
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<br>
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Default Public Authority: *USE<br>
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<!-- iddvc RMBR -->
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<br>
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Threadsafe: Yes<br>
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<!-- iddvc RMBR -->
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<br>
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</div>
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<p>The <strong>getitimer()</strong> function returns the value last used to set
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the interval timer specified by <em>which</em> in the structure pointed to by
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<em>value</em>.</p>
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<br>
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<!-- Please NOTE: DO NOT DELETE THIS SECTION if this API has no authorities and locks. -->
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<!-- Instead, use the commented out coding below to indicate NONE. -->
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<h3>Authorities and Locks</h3>
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<!-- Use this if there are no authorities and locks. -->
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<p>None.</p>
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<br>
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<h3>Parameters</h3>
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<dl>
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<dt><strong><em>which</em></strong></dt>
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<dd>(Input) The interval timer type.
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<p>The possible values for <em>which</em>, which are defined in the
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<<strong>sys/time.h</strong>> header file, are as follows:</p>
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<table cellpadding="5">
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<!-- cols="20 80" -->
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<tr>
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<td align="left" valign="top"><em>ITIMER_REAL</em></td>
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<td align="left" valign="top">The interval timer value is decremented in real
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time. The SIGALRM signal is generated for the process when this timer
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expires.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>ITIMER_VIRTUAL</em></td>
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<td align="left" valign="top">The interval timer value is only decremented when
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the process is running. The SIGVTALRM signal is generated for the process when
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this timer expires.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>ITIMER_PROF</em></td>
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<td align="left" valign="top">The interval timer value is only decremented when
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the process is running or when the system is running on behalf of the process.
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The SIGPROF signal is generated for the process when this timer expires.</td>
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</tr>
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</table>
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<br>
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</dd>
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<dt><strong><em>value</em></strong></dt>
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<dd>(Output) A pointer to the space where the current interval timer value is
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stored.</dd>
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</dl>
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<br>
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<h3>Return Value</h3>
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<table cellpadding="5">
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<!-- cols="5 95" -->
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<tr>
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<td align="left" valign="top"><em>0</em></td>
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<td align="left" valign="top"><strong>getitimer()</strong> was successful.</td>
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</tr>
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<tr>
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<td align="left" valign="top"><em>-1</em></td>
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<td align="left" valign="top"><strong>getitimer()</strong> was not successful.
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The <em>errno</em> variable is set to indicate the error.</td>
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</tr>
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</table>
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<br>
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<h3>Error Conditions</h3>
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<p>If <strong>getitimer()</strong> is not successful, <em>errno</em> usually
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indicates the following error. Under some conditions, <em>errno</em> could
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indicate an error other than that listed here.</p>
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<dl compact>
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<dt><em>[EINVAL]</em></dt>
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<dd>
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<p>The value specified for the argument is not correct.</p>
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<p>A function was passed incorrect argument values, or an operation was
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attempted on an object and the operation specified is not supported for that
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type of object.</p>
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<p>An argument value is not valid, out of range, or NULL.</p>
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<ul>
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<li>The value of <em>which</em> is not equal to one of the defined values.</li>
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</ul>
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<br>
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</dd>
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<dt><em>[ENOTSIGINIT]</em></dt>
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<dd>
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<p>Process not enabled for signals.</p>
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<p>An attempt was made to call a signal function under one of the following
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conditions:</p>
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<ul>
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<li>The signal function is being called for a process that is not enabled for
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asynchronous signals.</li>
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<li>The signal function is being called when the system signal controls have
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not been initialized.</li>
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</ul>
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</dd>
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</dl>
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<br>
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<h3>Related Information</h3>
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<ul>
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<li>The <<strong>sys/time.h</strong>> file (see <a href="unix13.htm">
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Header Files for UNIX-Type Functions</a>)<br>
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<br>
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</li>
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<li><a href="sigalarm.htm">alarm()</a>--Set Schedule for Alarm Signal<br>
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<br>
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</li>
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<li><a href="setitime.htm">setitimer()</a>--Set Value for Interval Timer<br>
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<br>
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</li>
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<li><a href="sigsleep.htm">sleep()</a>--Suspend Processing for Interval of
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Time<br>
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<br>
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</li>
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<li><a href="usleep.htm">usleep()</a>--Suspend Processing for Interval of
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Time</li>
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</ul>
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<br>
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<h3>Example</h3>
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<p>See <a href="../apiref/aboutapis.htm#codedisclaimer">Code disclaimer information</a>
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for information pertaining to code examples.</p>
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<p>The following example returns the current interval timer value using the
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<strong>getitimer()</strong> function:</p>
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<pre>
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#include <sys/time.h>
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#include <signal.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <time.h>
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#include <errno.h>
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#define LOOP_LIMIT 1E12
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volatile int sigcount=0;
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void catcher( int sig ) {
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struct itimerval value;
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int which = ITIMER_REAL;
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printf( "Signal catcher called for signal %d\n", sig );
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sigcount++;
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if( sigcount > 1 ) {
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/*
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* Disable the real time interval timer
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*/
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getitimer( which, &value );
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value.it_value.tv_sec = 0;
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value.it_value.tv_usec = 0;
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setitimer( which, &value, NULL );
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}
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}
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int main( int argc, char *argv[] ) {
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int result = 0;
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struct itimerval value, ovalue, pvalue;
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int which = ITIMER_REAL;
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struct sigaction sact;
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volatile double count;
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time_t t;
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sigemptyset( &sact.sa_mask );
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sact.sa_flags = 0;
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sact.sa_handler = catcher;
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sigaction( SIGALRM, &sact, NULL );
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getitimer( which, &pvalue );
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/*
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* Set a real time interval timer to repeat every 200 milliseconds
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*/
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value.it_interval.tv_sec = 0; /* Zero seconds */
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value.it_interval.tv_usec = 200000; /* Two hundred milliseconds */
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value.it_value.tv_sec = 0; /* Zero seconds */
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value.it_value.tv_usec = 500000; /* Five hundred milliseconds */
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result = setitimer( which, &value, &ovalue );
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/*
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* The interval timer value returned by setitimer() should be
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* identical to the timer value returned by getitimer().
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*/
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if( ovalue.it_interval.tv_sec != pvalue.it_interval.tv_sec ||
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ovalue.it_interval.tv_usec != pvalue.it_interval.tv_usec ||
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ovalue.it_value.tv_sec != pvalue.it_value.tv_sec ||
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ovalue.it_value.tv_usec != pvalue.it_value.tv_usec ) {
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printf( "Real time interval timer mismatch\n" );
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result = -1;
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}
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time( &t );
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printf( "Before loop, time is %s", ctime(&t) );
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for( count=0; ((count<LOOP_LIMIT) && (sigcount<2)); count++ );
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time( &t );
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printf( "After loop, time is %s\n", ctime(&t) );
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if( sigcount == 0 )
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printf( "The signal catcher never gained control\n" );
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else
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printf( "The signal catcher gained control\n" );
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printf( "The value of count is %.0f\n", count );
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return( result );
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}
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</pre>
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<br>
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<h3>Output:</h3>
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<pre>
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Before loop, time is Sun Jun 15 10:14:00 1997
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Signal catcher called for signal 14
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Signal catcher called for signal 14
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After loop, time is Sun Jun 15 10:14:01 1997
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The signal catcher gained control
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The value of count is 702943
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</pre>
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<br>
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<hr>
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API introduced: V4R2
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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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