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add uip git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1125 bbd45198-f89e-11dd-88c7-29a3b14d5316
2010-11-27 00:27:45 +08:00
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<title>uIP 1.0: Timer library</title>
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<h1>Timer library</h1><hr><a name="_details"></a><h2>Detailed Description</h2>
The timer library provides functions for setting, resetting and restarting timers, and for checking if a timer has expired.
<p>
An application must "manually" check if its timers have expired; this is not done automatically.<p>
A timer is declared as a <code>struct</code> <code>timer</code> and all access to the timer is made by a pointer to the declared timer.<p>
<dl compact><dt><b>Note:</b></dt><dd>The timer library uses the <a class="el" href="a00157.html">Clock library</a> to measure time. Intervals should be specified in the format used by the clock library. </dd></dl>
<p>
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<tr><td colspan="2"><br><h2>Files</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">file &nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00130.html">timer.h</a></td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Timer library header file. <br></td></tr>
<p>
<tr><td class="memItemLeft" nowrap align="right" valign="top">file &nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00129.html">timer.c</a></td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Timer library implementation. <br></td></tr>
<p>
<tr><td colspan="2"><br><h2>Data Structures</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">struct &nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00087.html">timer</a></td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">A timer. <a href="a00087.html#_details">More...</a><br></td></tr>
<tr><td colspan="2"><br><h2>Functions</h2></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00156.html#g6614d96fdfcd95c95ec6e6f63071ff51">timer_set</a> (struct <a class="el" href="a00087.html">timer</a> *t, clock_time_t interval)</td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Set a timer. <a href="#g6614d96fdfcd95c95ec6e6f63071ff51"></a><br></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00156.html#gedaf3e48c2b04229b85455fb948468d6">timer_reset</a> (struct <a class="el" href="a00087.html">timer</a> *t)</td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Reset the timer with the same interval. <a href="#gedaf3e48c2b04229b85455fb948468d6"></a><br></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">void&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00156.html#gcb807bd57e5489b386b876af5c1f163a">timer_restart</a> (struct <a class="el" href="a00087.html">timer</a> *t)</td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Restart the timer from the current point in time. <a href="#gcb807bd57e5489b386b876af5c1f163a"></a><br></td></tr>
<tr><td class="memItemLeft" nowrap align="right" valign="top">int&nbsp;</td><td class="memItemRight" valign="bottom"><a class="el" href="a00156.html#g6d71dececfce707c668e6257aad5906e">timer_expired</a> (struct <a class="el" href="a00087.html">timer</a> *t)</td></tr>
<tr><td class="mdescLeft">&nbsp;</td><td class="mdescRight">Check if a timer has expired. <a href="#g6d71dececfce707c668e6257aad5906e"></a><br></td></tr>
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<hr><h2>Function Documentation</h2>
<a class="anchor" name="g6d71dececfce707c668e6257aad5906e"></a><!-- doxytag: member="timer.h::timer_expired" ref="g6d71dececfce707c668e6257aad5906e" args="(struct timer *t)" --><p>
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<td class="md" nowrap valign="top">int timer_expired </td>
<td class="md" valign="top">(&nbsp;</td>
<td class="md" nowrap valign="top">struct <a class="el" href="a00087.html">timer</a> *&nbsp;</td>
<td class="mdname1" valign="top" nowrap> <em>t</em> </td>
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<p>
Check if a timer has expired.
<p>
This function tests if a timer has expired and returns true or false depending on its status.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>t</em>&nbsp;</td><td>A pointer to the timer</td></tr>
</table>
</dl>
<dl compact><dt><b>Returns:</b></dt><dd>Non-zero if the timer has expired, zero otherwise. </dd></dl>
<dl compact><dt><b>Examples: </b></dt><dd>
<a class="el" href="a00048.html#a26">dhcpc.c</a>, <a class="el" href="a00042.html#a77">example-mainloop-with-arp.c</a>, and <a class="el" href="a00043.html#a94">example-mainloop-without-arp.c</a>.</dl>
<p>
Definition at line <a class="el" href="a00195.html#l00121">121</a> of file <a class="el" href="a00195.html">timer.c</a>.
<p>
References <a class="el" href="a00157.html#ge5b7160f2e653725ba5e2024c3cb7bff">clock_time()</a>, <a class="el" href="a00196.html#l00076">interval</a>, and <a class="el" href="a00196.html#l00075">start</a>. </td>
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<a class="anchor" name="gedaf3e48c2b04229b85455fb948468d6"></a><!-- doxytag: member="timer.h::timer_reset" ref="gedaf3e48c2b04229b85455fb948468d6" args="(struct timer *t)" --><p>
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<td class="md" nowrap valign="top">void timer_reset </td>
<td class="md" valign="top">(&nbsp;</td>
<td class="md" nowrap valign="top">struct <a class="el" href="a00087.html">timer</a> *&nbsp;</td>
<td class="mdname1" valign="top" nowrap> <em>t</em> </td>
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<p>
Reset the timer with the same interval.
<p>
This function resets the timer with the same interval that was given to the <a class="el" href="a00156.html#g6614d96fdfcd95c95ec6e6f63071ff51">timer_set()</a> function. The start point of the interval is the exact time that the timer last expired. Therefore, this function will cause the timer to be stable over time, unlike the timer_rester() function.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>t</em>&nbsp;</td><td>A pointer to the timer.</td></tr>
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</dl>
<dl compact><dt><b>See also:</b></dt><dd><a class="el" href="a00156.html#gcb807bd57e5489b386b876af5c1f163a">timer_restart()</a> </dd></dl>
<dl compact><dt><b>Examples: </b></dt><dd>
<a class="el" href="a00042.html#a78">example-mainloop-with-arp.c</a>, and <a class="el" href="a00043.html#a95">example-mainloop-without-arp.c</a>.</dl>
<p>
Definition at line <a class="el" href="a00195.html#l00084">84</a> of file <a class="el" href="a00195.html">timer.c</a>.
<p>
References <a class="el" href="a00196.html#l00076">interval</a>, and <a class="el" href="a00196.html#l00075">start</a>. </td>
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<a class="anchor" name="gcb807bd57e5489b386b876af5c1f163a"></a><!-- doxytag: member="timer.h::timer_restart" ref="gcb807bd57e5489b386b876af5c1f163a" args="(struct timer *t)" --><p>
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<td class="md" nowrap valign="top">void timer_restart </td>
<td class="md" valign="top">(&nbsp;</td>
<td class="md" nowrap valign="top">struct <a class="el" href="a00087.html">timer</a> *&nbsp;</td>
<td class="mdname1" valign="top" nowrap> <em>t</em> </td>
<td class="md" valign="top">&nbsp;)&nbsp;</td>
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<p>
Restart the timer from the current point in time.
<p>
This function restarts a timer with the same interval that was given to the <a class="el" href="a00156.html#g6614d96fdfcd95c95ec6e6f63071ff51">timer_set()</a> function. The timer will start at the current time.<p>
<dl compact><dt><b>Note:</b></dt><dd>A periodic timer will drift if this function is used to reset it. For preioric timers, use the <a class="el" href="a00156.html#gedaf3e48c2b04229b85455fb948468d6">timer_reset()</a> function instead.</dd></dl>
<dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>t</em>&nbsp;</td><td>A pointer to the timer.</td></tr>
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</dl>
<dl compact><dt><b>See also:</b></dt><dd><a class="el" href="a00156.html#gedaf3e48c2b04229b85455fb948468d6">timer_reset()</a> </dd></dl>
<p>
Definition at line <a class="el" href="a00195.html#l00104">104</a> of file <a class="el" href="a00195.html">timer.c</a>.
<p>
References <a class="el" href="a00157.html#ge5b7160f2e653725ba5e2024c3cb7bff">clock_time()</a>, and <a class="el" href="a00196.html#l00075">start</a>. </td>
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<a class="anchor" name="g6614d96fdfcd95c95ec6e6f63071ff51"></a><!-- doxytag: member="timer.h::timer_set" ref="g6614d96fdfcd95c95ec6e6f63071ff51" args="(struct timer *t, clock_time_t interval)" --><p>
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<td class="md" nowrap valign="top">void timer_set </td>
<td class="md" valign="top">(&nbsp;</td>
<td class="md" nowrap valign="top">struct <a class="el" href="a00087.html">timer</a> *&nbsp;</td>
<td class="mdname" nowrap> <em>t</em>, </td>
</tr>
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<td class="md" nowrap align="right"></td>
<td class="md"></td>
<td class="md" nowrap>clock_time_t&nbsp;</td>
<td class="mdname" nowrap> <em>interval</em></td>
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<td class="md"></td>
<td class="md">)&nbsp;</td>
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<p>
Set a timer.
<p>
This function is used to set a timer for a time sometime in the future. The function <a class="el" href="a00156.html#g6d71dececfce707c668e6257aad5906e">timer_expired()</a> will evaluate to true after the timer has expired.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
<table border="0" cellspacing="2" cellpadding="0">
<tr><td valign="top"></td><td valign="top"><em>t</em>&nbsp;</td><td>A pointer to the timer </td></tr>
<tr><td valign="top"></td><td valign="top"><em>interval</em>&nbsp;</td><td>The interval before the timer expires. </td></tr>
</table>
</dl>
<dl compact><dt><b>Examples: </b></dt><dd>
<a class="el" href="a00048.html#a22">dhcpc.c</a>, <a class="el" href="a00042.html#a62">example-mainloop-with-arp.c</a>, and <a class="el" href="a00043.html#a86">example-mainloop-without-arp.c</a>.</dl>
<p>
Definition at line <a class="el" href="a00195.html#l00064">64</a> of file <a class="el" href="a00195.html">timer.c</a>.
<p>
References <a class="el" href="a00157.html#ge5b7160f2e653725ba5e2024c3cb7bff">clock_time()</a>, <a class="el" href="a00196.html#l00076">interval</a>, and <a class="el" href="a00196.html#l00075">start</a>. </td>
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