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

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

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

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

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

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

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

<concept id="GUID-AF2E227B-C5BD-5F05-98D4-7D15530161C8" xml:lang="en"><title>Interrupt::Clear()</title><shortdesc>Describes the implementation of the clear function.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The function <xref href="GUID-E7A7083C-97B9-39B9-A147-4A6E314EE3A3.dita#GUID-E7A7083C-97B9-39B9-A147-4A6E314EE3A3/GUID-DB641A23-82B2-373E-A514-E11118CB6E69"><apiname>Interrupt::Clear()</apiname></xref> is used by device drivers

to acknowledge that they have serviced the interrupt and cleared the pending

flag in the interrupt controller hardware. </p>

<p>This is useful in situations where an interrupt must be cleared explicitly

rather than as a side effect of an I/O register access, especially where the

clearing is done from generic code such as in the PC card and MMC controllers. </p>

<p>The implementation of this function is completely dependent on the interrupt

hardware. </p>

<p>In the template port, <codeph>Interrupt::Clear()</codeph> is implemented

in <filepath>...\template_assp\interrupts.cpp</filepath>. </p>

<codeblock id="GUID-7612CEB2-7ADA-552D-9BB9-B0B1B2D8E4BC" xml:space="preserve">EXPORT_C TInt Interrupt::Clear(TInt anId)

    {

     __KTRACE_OPT(KEXTENSION,Kern::Printf("Interrupt::Clear id=%d",anId));

     TInt r=KErrNone;

     // if ID indicates a chained interrupt, call variant...

     if (anId<0 && ((((TUint)anId)>>16)&0x7fff)<(TUint)KNumTemplateInts)

         r=TemplateAssp::Variant->InterruptClear(anId);

     else if ((TUint)anId>=(TUint)KNumTemplateInts)

         r=KErrArgument;

     else

         {

         //

         // TO DO: (mandatory)

         //

         // Clear the corresponding Hardware Interrupt source

         //

        }

    return r;

    }</codeblock>

</conbody></concept>