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1 <?xml version="1.0" encoding="utf-8"?> |
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2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. --> |
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3 <!-- This component and the accompanying materials are made available under the terms of the License |
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4 "Eclipse Public License v1.0" which accompanies this distribution, |
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5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". --> |
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6 <!-- Initial Contributors: |
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7 Nokia Corporation - initial contribution. |
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8 Contributors: |
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9 --> |
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10 <!DOCTYPE concept |
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11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
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12 <concept id="GUID-2281F91F-67BD-5B85-A47F-30A5E683BBF6" xml:lang="en"><title>Double |
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13 Buffers</title><shortdesc>To improve throughput, Symbian platform provides the double buffer |
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14 mechanism. This is a feature that allows a block of data to be prepared by |
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15 the media driver while the hardware transfers a block of data. DMA transfers |
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16 data without interrupting the CPU. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody> |
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17 <p>The MultiMediaCard subsystem performs multiple data transfers in a single |
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18 bus transaction. </p> |
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19 <p>If your implementation uses double buffers, you must set the <codeph>ESupportsDoubleBuffering</codeph> flag |
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20 into the <xref href="GUID-A8C79421-AA44-345D-9863-EA21F5FEEE72.dita#GUID-A8C79421-AA44-345D-9863-EA21F5FEEE72/GUID-8B9C1B71-9664-35B8-B3B3-EC5508E8E76A"><apiname>TMMCMachineInfoV4::iFlags</apiname></xref> data member in your |
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21 implementation of <xref href="GUID-B5193656-9819-3E00-A335-EEF1726115A5.dita#GUID-B5193656-9819-3E00-A335-EEF1726115A5/GUID-3E5532A5-4645-3F77-A7A9-7AFF334FA5A4"><apiname>DMMCStack::MachineInfo()</apiname></xref>. This flag causes |
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22 the platform independent layer to provide the support you need. </p> |
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23 <p>If your MultiMediaCard controller uses DMA and your platform specific layer |
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24 supports physical addresses, you must use double buffers. </p> |
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25 <p>See also: </p> |
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26 <ul> |
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27 <li id="GUID-629116CA-4B19-5F48-9F0D-0FEED4D26FEB"><p> <xref href="GUID-E55B4FE5-517C-5A23-8ACA-E28EE202330B.dita#GUID-E55B4FE5-517C-5A23-8ACA-E28EE202330B/GUID-CEF0EDF7-4B33-5452-8635-51C5319F78AE">MachineInfo()</xref> </p> </li> |
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28 <li id="GUID-5EF23F02-273E-5382-86C4-C04520AFD91E"><p> <xref href="GUID-E55B4FE5-517C-5A23-8ACA-E28EE202330B.dita#GUID-E55B4FE5-517C-5A23-8ACA-E28EE202330B/GUID-E50081BC-C923-5DAF-950C-9E1411916FED">Implement double buffers</xref> </p> </li> |
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29 </ul> |
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30 </conbody></concept> |