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<!DOCTYPE concept
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-DD568637-CD37-5E4C-AD78-4AA5AFE1E9D8" xml:lang="en"><title>Entry
Point Implementation</title><shortdesc>Media driver must implement an entry point function that creates
a PDD factory object that is derived from <codeph>DPhysicalDevice</codeph>.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>Because media drivers are implemented as kernel extensions, use the <xref href="GUID-F10BBEC9-FC49-3B85-9B7F-9A6DB66A7B30.dita"><apiname>DECLARE_EXTENSION_PDD()</apiname></xref> macro
as a wrapper around the code that creates your factory object; the following
code fragment is typical: </p>
<codeblock id="GUID-BE6811EF-1FA7-58D2-89AC-12887B49DA5B" xml:space="preserve">DECLARE_EXTENSION_PDD()
    {
    return new DMyPhysicalDevice;
    } </codeblock>
<p>where <codeph>DMyPhysicalDevice</codeph> is an implementation of <xref href="GUID-A5484A7F-94B9-34C7-9F88-82B1BF516930.dita"><apiname>DPhysicalDevice</apiname></xref>. </p>
</conbody></concept>