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<!DOCTYPE concept

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<concept id="GUID-DEA883D0-7C53-407A-AC5D-0A3208E667C7" xml:lang="en"><title>EGL

Reusable Sync Extension</title><shortdesc>This topic describes the EGL reusable sync extension, which introduces

sync objects into EGL. Sync objects provide a synchronization mechanism and

represent events, whose completion can be tested or waited on. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The following table provides a link to the specification.</p>

<table id="GUID-3E2BB969-C9C3-473B-B448-5BEAA279619B">

<tgroup cols="2"><colspec colname="col1" colwidth="0.20*"/><colspec colname="col2" colwidth="1.80*"/>

<thead>

<row>

<entry valign="top">Version </entry>

<entry valign="top">Specification</entry>

</row>

</thead>

<tbody>

<row>

<entry>Version 20</entry>

<entry><xref href="http://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_reusable_sync.txt" scope="external">http://www.khronos.org/registry/egl/extensions/KHR/EGL_KHR_reusable_sync.txt</xref></entry>

</row>

</tbody>

</tgroup>

</table>

<p>The OpenWF-C Engine and Support components use EGL sync objects for synchronization.

Therefore the EGL implementation must support the extension if OpenWF composition

is in use. The EGL Reference Implementation component implements the extension. </p>

<p>The following table lists the reusable sync extension APIs.

Clients obtain an extension function by calling <codeph>eglGetProcAddress()</codeph> and

pass in the function name.</p>

<table id="GUID-CE850680-15FF-4861-8B03-5D56125282D7">

<tgroup cols="2"><colspec colname="col1"/><colspec colname="col2"/>

<thead>

<row>

<entry valign="top">Function</entry>

<entry valign="top">Description</entry>

</row>

</thead>

<tbody>

<row>

<entry><codeph>eglCreateSyncKHR()</codeph></entry>

<entry>Creates a sync object which is associated with the initialized EGL

display and whose status is unsignaled.</entry>

</row>

<row>

<entry><codeph>eglDestroySyncKHR()</codeph></entry>

<entry>Destroys an existing sync object.</entry>

</row>

<row>

<entry><codeph>eglClientWaitSyncKHR()</codeph></entry>

<entry>Blocks the calling thread until the sync object is signaled or after

the specified timeout period.</entry>

</row>

<row>

<entry><codeph>eglSignalSyncKHR()</codeph></entry>

<entry>Signals or unsignals the sync object. </entry>

</row>

<row>

<entry><codeph>eglGetSyncAttribKHR()</codeph></entry>

<entry>Queries attributes of the sync object.</entry>

</row>

</tbody>

</tgroup>

</table>

<codeblock xml:space="preserve"/>

</conbody><related-links>

<link href="GUID-A5914CFF-6F86-53E8-9928-36D3379835B1.dita"><linktext>EGL Interface

Overview</linktext></link>

<link href="GUID-894AB487-C127-532D-852B-37CB0DEA1440.dita"><linktext>Symbian-Specific

Behavior</linktext></link>

<link href="GUID-46813F51-370B-5853-917C-6916925A347D.dita"><linktext>EGL Tutorial</linktext>

</link>

<link href="GUID-DC8BFEF5-DA50-52DA-8CE2-5729A4A005F6.dita"><linktext>EGL Collection

Overview</linktext></link>

<link href="GUID-83510B5B-9725-5272-BF51-23A089178DAC.dita">

<linktext>OpenWF Support Component Overview</linktext></link>