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9<title>VIGetRetraceCount</title>
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14<h1 align="left">VIGetRetraceCount</h1>
15
16<h2>C Specification</h2>
17
18<dl>
19<dd><pre><code>#include &lt;revolution/vi.h&gt;</code></pre>
20  </dd>
21<dd><pre><code>u32 VIGetRetraceCount(void)</code></pre>
22  </dd>
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24
25<h2>Arguments</h2>
26
27<p>None.</p>
28
29<h2>Return Values</h2>
30
31<p>The number of retrace interrupts.</p>
32
33<h2>Description</h2>
34
35<p>This function returns how many retrace interrupts have occurred since the <a href="VIInit.html"><code>VIInit</code></a> function was called.</p>
36
37<h2>Sample Code</h2>
38
39<p>The following code shows how to achieve 30Hz rendering using this function:</p>
40
41<blockquote>
42<code><p>VIWaitForRetrace(); // just to make sure the first frame starts<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// from the very beginning of the field.<br> while(1) {<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;count = VIGetRetraceCount();<br> <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;// rendering<br> <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;while (VIGetRetraceCount() == count)<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;;<br> <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;VISetNextFrameBuffer(nextbuffer);<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;VIFlush();<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;VIWaitForRetrace();<br> }</code></p>
43</blockquote>
44
45<h2>See Also</h2>
46
47<p><a href="VIInit.html"><code>VIInit</code></a></p>
48
49<h2>Revision History</h2>
50
51<P>03/01/2006 Initial version.</p>
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