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Adaptation/GUID-B4C05C46-F2C9-57FA-AD85-EFE6479C2FF1.dita
author Graeme Price <GRAEME.PRICE@NOKIA.COM>
Fri, 15 Oct 2010 14:32:18 +0100
changeset 15 307f4279f433
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Initial contribution of the Adaptation Documentation.
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<?xml version="1.0" encoding="utf-8"?>
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<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
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<!-- This component and the accompanying materials are made available under the terms of the License
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"Eclipse Public License v1.0" which accompanies this distribution,
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and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
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<!-- Initial Contributors:
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    Nokia Corporation - initial contribution.
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Contributors:
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-->
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<!DOCTYPE concept
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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
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<concept id="GUID-B4C05C46-F2C9-57FA-AD85-EFE6479C2FF1" xml:lang="en"><title>Design</title><shortdesc>When you start a port, you must make a decision if the driver must
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provide record, playback, or both playback and record.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
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<p>If the PDD is to support audio transfer in a single direction, either record
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or playback, then a conventional PDD implementation is required. The PDD opens
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only a single driver channel and the PDD factory creates either a record or
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playback PDD object. </p>
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<p>If the PDD is to support audio transfer in both directions then it must
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be implemented to open two units, one playback unit and one record unit. For
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each unit the PDD factory must create the appropriate PDD object. </p>
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<p>One complication in this configuration is the need to co-ordinate access
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to the single audio hardware device from the two separate PDD objects. This
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configuration needs coordination when accessing the hardware device from two
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separate PDD objects, detecting and preventing situations where the handling
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of a PDD function for the channel in one direction conflicts with the channel
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setup in the other direction, specifically: </p>
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<ul>
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<li id="GUID-076CE21B-E350-5D87-A486-8AFC120E8DE9"><p>preventing the setup
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of conflicting audio configurations between the record and playback channels. </p> </li>
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<li id="GUID-27C1DD90-DE14-51CD-A723-86C7696D4C4F"><p>preventing the channel
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in one direction from powering down the audio hardware device while it is
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being used for data transfer by the other channel. </p> </li>
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</ul>
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<p>The solution is to move the code that controls those aspects of audio hardware
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setup which are shared between the two driver channels into the PDD factory
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object, as this object is shared. </p>
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<p>The porting process focuses on implementing a PDD that supports both record
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and playback as this is the most common situation. The template port Sound
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Driver is setup for this configuration. A PDD that supports audio transfer
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in a single direction only omits the implementation for the direction not
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supported. </p>
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</conbody></concept>
MCL/sftools/depl/docscontent