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<concept id="GUID-F7249C66-B62F-45DF-B733-BC6D5FCDA003" xml:lang="en"><title>Completion and Notification</title><shortdesc>This document describes how a device driver notifies completion

of an asynchronous request.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>On completion of the request, the driver calls <xref href="GUID-C6946ECB-775F-3EC2-A56F-78F25B9FBE3D.dita#GUID-C6946ECB-775F-3EC2-A56F-78F25B9FBE3D/GUID-D720BB4C-5E31-3213-BB16-859AA325FE98"><apiname>Kern::RequestComplete()</apiname></xref>,

passing the <codeph>TRequestStatus</codeph> object and completion error code,

to notify the request completion to the user. This API internally sets the

passed error code in the <codeph>TRequestStatus</codeph> object. It also signals

the client's thread semaphore. </p>

<codeblock id="GUID-D6016CEF-C1F8-5743-97E3-E0E9E2C92547" xml:space="preserve">void DExDriverLogicalChannel::DoTxDataComplete()

    {

    ...

    // Notify the client (iClient) that the request is completed. The  

    // TRequestStatus object is updated with the status and the 

    // completion code is provided to the client. Typically, the client 

    // thread, waiting using User::WaitForRequest(TRequestStatus 

    // &aStatus) or the active object framework, is unblocked and 

    // notified. Then the client may read the request status from the 

    // TRequestStatus object.

    // 

    Kern::RequestComplete(iClient,iTxDataStatus,iTxResult);

    }</codeblock>

<p>The user retrieves the result of the request by calling <xref href="GUID-8005774C-A9AA-3335-B918-51190A125134.dita#GUID-8005774C-A9AA-3335-B918-51190A125134/GUID-BC53014D-0801-3168-9FDE-9D5897A7AA8A"><apiname>TRequestStaus::Int()</apiname></xref>. </p>