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9<title>VISetPostRetraceCallback</title>
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14<h1 align="left">VISetPostRetraceCallback</h1>
15
16<h2>C Specification</h2>
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18<dl>
19<dd><pre><code>#include &lt;revolution/vi.h&gt;</code></pre>
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21<dd><pre><code>typedef void (*VIRetraceCallback)(u32 <em>retraceCount</em>);</code></pre>
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23<dd><pre><code>VIRetraceCallback VISetPostRetraceCallback(VIRetraceCallback <em>callback</em>)</code></pre>
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27<h2>Arguments</h2>
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29<table border="1" cellpadding="3" cellspacing="0.1">
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32<td width="120" bgcolor="#ffffe8"><em><strong><code>callback</code></strong></em></td>
33<td width="520">A pointer to the post-retrace callback function</td>
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37
38<h2>Return Values</h2>
39
40<p>Pointer to the previous callback function.</p>
41
42<h2>Description</h2>
43
44<p>This function sets the post-retrace callback. That callback is a function called after the VI device driver's retrace interrupt handler sets the VI registers.</p>
45
46<p>It returns the pointer to the previous callback function.</p>
47
48<p>Specifying NULL for <code>callback</code> means that no callback is specified as a post-retrace callback. Similarly, NULL is returned when no callback is specified before. Since no callback is specified by default, the first call to this function should return NULL. You can cancel a callback you set previously by specifying NULL to <i><code>callback</code></i>.</p>
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50<p>The retrace count, which is passed to the callback function as an argument, is incremented once every 1/60 second in NTSC/MPAL/EURGB60 modes (or once every 1/50 second in PAL mode).</p>
51
52<h2>See Also</h2>
53
54<p><code><a href="VISetPreRetraceCallback.html">VISetPreRetraceCallback</a></code>, <code><a href="VIWaitForRetrace.html">VIWaitForRetrace</a></code></p>
55
56<h2>Revision History</h2>
57
58<p>2006/03/01 Initial version.</p>
59<hr>
60<P>CONFIDENTIAL</p>
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