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

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

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

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     7     Nokia Corporation - initial contribution.

     8 Contributors: 

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    10 <!DOCTYPE concept

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

    12 <concept id="GUID-C3C89BD7-A56D-4597-8804-01A25BC71581" xml:lang="en"><title>Data

    13 Transfer between LDD and PDD</title><shortdesc>This document describes how LDDs and PDDs exchange data.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <section id="GUID-F65FC583-DDC7-40B6-B875-44A8D11A2971">      

    15       <p>The device driver framework supplies each LDD with a pointer, <xref href="GUID-E7550422-5121-3393-A85E-BB797969CD2A.dita#GUID-E7550422-5121-3393-A85E-BB797969CD2A/GUID-CF58D3F1-8185-3A91-A7E8-338B43D329A5"><apiname>DLogicalChannelBase::iPdd</apiname></xref>,

    16 through which it can access PDD functions. The pointer is initialised by the

    17 Kernel while creating a physical channel. </p> <p>An example of this pointer

    18 in use: </p> <codeblock id="GUID-55814834-E7CD-5F19-BA09-B91DA25C8FE3" xml:space="preserve">inline DExUartPhysicalChannel * DExDriverLogicalChannel::Pdd()

    19     { return (DExUartPhysicalChannel *)iPdd; }

    20 

    21 // example use

    22 Pdd()-&gt;SetDfcQ();</codeblock> <p>Similarly, a PDD can access a LDD, though

    23 this access must be initialised by the LDD. In the following example, the

    24 physical channel declares a pointer to a logical channel, which the LDD sets.

    25 Callbacks to the LDD are done using this pointer. </p> <codeblock id="GUID-A4A52268-B5B9-53D4-9F69-B506F268201D" xml:space="preserve">// PDD channel class

    26 class DExH4PhysicalChannel: public DBase

    27     {

    28     ...

    29 public:

    30     DExDriverLogicalChannel* iLdd;

    31     }

    32 

    33 // Second stage constructor of Logical channel

    34 TInt DExDriverLogicalChannel::DoCreate(TInt /*aUnit*/, const TDesC8*

    35         /*anInfo*/, const TVersion& aVer)

    36     {

    37     ...

    38     Pdd()->iLdd=this;

    39     }

    40 

    41 // example use in PDD

    42 iLdd-&gt;ReceiveDataComplete(KErrNone);</codeblock> <p>The logical channel class, <xref href="GUID-E7550422-5121-3393-A85E-BB797969CD2A.dita"><apiname>DLogicalChannelBase</apiname></xref>,

    43 also has pointers to a logical device (<codeph>iDevice</codeph>) and a physical

    44 device (<codeph>iPhysicalDevice</codeph>). These pointers are initialised

    45 during the driver loading and channel open operations, so they can also be

    46 used to pass information between the LDD and PDD. </p> <codeblock id="GUID-4B86BED0-22CB-53BC-A1C7-9BEB0CEA1EDE" xml:space="preserve">class DLogicalChannelBase: public DObject

    47     {

    48     ...

    49 public:

    50     DLogicalDevice* iDevice;

    51     DPhysicalDevice* iPhysicalDevice;

    52     DBase* iPdd;

    53     }

    54 

    55 // example use

    56 TDynamicDfcQue* DExUartPhysicalChannelH4::DfcQ(TInt aUnit)

    57     {    

    58     ...

    59     return ((DExH4PhysicalDevice*)

    60             (iLdd->iPhysicalDevice))->iDfcQueue;    

    61     }</codeblock>     </section>

    62 </conbody></concept>