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<concept xml:lang="en" id="GUID-8DA87C97-AF29-5209-BEB6-0C549757254E"><title>Hardware Resource Manager Plug-in Tutorial</title><shortdesc>This tutorial describes how to write the plug-ins for HWRM. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><section id="GUID-837884A8-DFBB-5B13-A961-BCC62AFB3A7E"><title>Introduction</title> <p>Symbian developers must implement the <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginService</apiname></xref> in their plug-in. The HWRM plug-in must create a new instance of the <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginServices</apiname></xref> using <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginService::NewL()</apiname></xref> method. A string and a callback pointer are passed as the parameters. The common strings used to identify the plug-in are <codeph>HWRMLight</codeph>, <codeph>HWRMVibra</codeph> and <codeph>HWRMPower</codeph>. The callback pointer is provided by the <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>MHWRMPluginCallback</apiname></xref> class. </p> <p>The client APIs requests are forwarded to the plug-in using a <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginServices::ProcessCommandL()</apiname></xref>. <codeph>Command
          ID</codeph>, <codeph>transaction ID</codeph> and <codeph>command data</codeph> are passed as parameters. The plug-in communicates with the hardware using proprietary software developed by the licensees and convert the client requests into hardware control commands. After processing a request, the plug-in acknowledges the server by calling the <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>MHWRMPluginCallback::ProcessResponseL()</apiname></xref> callback function. The same command ID and transaction ID are passed as the parameters. An error code is also included in the acknowledgement message. </p> <p>Every <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>MHWRMPluginCallback::ProcessResponseL()</apiname></xref> is associated with an <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginServices::ProcessCommandL()</apiname></xref> request. Both functions can use asynchronous calls and leave. The HWRM server can cancel a <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginServices::ProcessCommandL()</apiname></xref> request by calling a <xref href="GUID-4603653B-34E4-3CC5-9978-95F9532A0616.dita"><apiname>CHWRMPluginService::CancelCommandL()</apiname></xref>. </p> </section> <section><title>Plug-in Configuration</title> <p>Configure HWRM plug-ins as an ECom plug-in. To load the plug-in correctly, the resource files must be configured carefully. </p> <p>The following code illustrates a sample resource file for Light and Vibra plug-ins: </p> <codeblock id="GUID-DDF2A6D0-C577-5F2C-8ED1-15543172CDB4" xml:space="preserve">
#include "RegistryInfoV2.rh"

//Sample resource file for Light and Vibra plug-ins

RESOURCE REGISTRY_INFO theInfo
    {
    resource_format_version = RESOURCE_FORMAT_VERSION_2;
    dll_uid = 0x12345678;
    interfaces = 
        {
        INTERFACE_INFO
            {
            // UID of interface that is implemented
            interface_uid = 0x10205028;
            implementations = 
                {
                IMPLEMENTATION_INFO
                    {
                    implementation_uid = 0x11223344;
                    version_no = 1;
                    display_name = "Light plugin stub";
                    default_data = "HWRMLight";      
                    opaque_data = "";
                    rom_only = 1;
                    },
                IMPLEMENTATION_INFO
                    {
                    implementation_uid = 0x55667788;
                    version_no = 1;
                    display_name = "Vibra plugin stub";
                    default_data = "HWRMVibra";      
                    opaque_data = "";
                    rom_only = 1;
                    }
                };
            }
        };
    }</codeblock> <p> <b>Note</b>: The value of <codeph>rom_only</codeph> must always be 1. The default data must be <codeph>HWRMLight</codeph>, <codeph>HWRMVibra</codeph>, <codeph>HWRMPower</codeph>. </p> </section> <example id="GUID-970B0B26-EBD0-557E-A4AE-8C40C908C538"><title>Sample Light plug-in example</title> <p>The following code snippet illustrates how a light plug-in is called by the HWRM server: </p> <codeblock id="GUID-ECC11C08-F70A-5636-9CE4-D4A15777192C" xml:space="preserve">
#include "HWRMpluginService.h"

_LIT8( KHWRMLightApiEComMatch, "HWRMLight" );

iPlugin = CHWRMPluginService::NewL( KHWRMLightApiEComMatch, this );
iTransCounter = 0;
. . .
HWRMLightCommand::TLightsOnData pluginCommand;
pluginCommand.iTarget = 0x00000001; // Set target to primary display 
pluginCommand.iIntensity = 50;
pluginCommand.iFadeIn = EFalse;    
HWRMLightCommand::TLightsOnCmdPackage pckg( pluginCommand );
iPlugin-&gt;ProcessCommandL( HWRMLightCommand::ELightsOnCmdId, iTransCounter++, pckg );

//Example of how ProcessResponseL() or EventL() might be handled

HWRMLightCommand::TErrorCodeResponsePackage errPckg;
errPckg.Copy( aData );
TInt pluginErr = errPckg();

// Handle error here
</codeblock> </example> </conbody></concept>