1 <?xml version="1.0" encoding="utf-8"?>

     2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

     3 <!-- This component and the accompanying materials are made available under the terms of the License 

     4 "Eclipse Public License v1.0" which accompanies this distribution, 

     5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

     6 <!-- Initial Contributors:

     7     Nokia Corporation - initial contribution.

     8 Contributors: 

     9 -->

    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-30978E00-D244-44CD-8F4E-9676DF172A52" xml:lang="en"><title>Driver-side

    13 Handling</title><shortdesc>This document describes how device drivers handle asynchronous

    14 requests.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    15 <p>Drivers generally implement the <xref href="GUID-9D910016-5611-30DD-A139-EE46705A4912.dita"><apiname>DoRequest()</apiname></xref> function

    16 in the LDD to handle the received asynchronous messages. </p>

    17 <p>The implementation reads the request type and other passed arguments, and

    18 initiates handling of the request appropriately. </p>

    19 <p>The return value of this function only indicates the status of the message

    20 reception to the driver. It does not actually indicate the request completion

    21 result. </p>

    22 <codeblock id="GUID-335BB3F8-7B2B-5FC4-A8D1-204E6B24FECD" xml:space="preserve">TInt DExDriverLogicalChannel::DoRequest(TInt aReqNo, TRequestStatus* aStatus,

    23         TAny* a1, TAny* a2)

    24     {

    25     switch (aReqNo)

    26         {

    27         case RExDriverChannel::ERequestTransmitData:

    28             // Call TransmitData function

    29             r = TransmitData ((const TDesC8*)a1);

    30             // The status object is stored 

    31             // to be used when notifying the completion of the 

    32             // request at a later point.

    33             //

    34             iTxDataStatus = aStatus;

    35             break;

    36         }

    37     return r;

    38     }</codeblock>

    39 </conbody></concept>