Factory +Implementation

The Sound Driver PDD must provide a factory class to create channels. All +PDD factory classes are derived from DPhysicalDevice. The +template PDD factory class TemplateSoundScPddFactory creates +the appropriate PDD object when a driver channel is opened on the device. +As well as the configurations supporting both record and playback, this class +implements control of those aspects of the audio hardware device that are +shared between the two channels.

DTemplateSoundScPddFactory is defined as:

+class DTemplateSoundScPddFactory : public DPhysicalDevice + { +public: + DTemplateSoundScPddFactory(); + ~DTemplateSoundScPddFactory(); + virtual TInt Install(); + virtual void GetCaps(TDes8& aDes) const; + virtual TInt Create(DBase*& aChannel, TInt aUnit, const TDesC8* aInfo, const TVersion& aVer); + virtual TInt Validate(TInt aUnit, const TDesC8* aInfo, const TVersion& aVer); +private: + /** The DFC queue (used also by the LDD). */ + TDynamicDfcQue* iDfcQ; + friend class DTemplateSoundScTxPdd; + friend class DTemplateSoundScRxPdd; + }; +

The PDD factory class provided by the template Sound Driver creates a new +DFC queue and associated kernel thread, iDfcQ, for exclusive +use by this pair of Sound Driver channels. This is created within the second +stage constructor function Install(). +A pointer to the DFC queue is returned by the PDD function DfcQ(). +See the PDD +class constructor section.

The class DTemplateSoundScPddFactory contains four virtual +functions, including the constructor, that must be implemented by the PDD +for both driver channels. The template Sound Driver contains default implementations +together with a constructor and destructor and, typically, need little or +no modification:

DTemplateSoundScPddFactory constructor
Install()
Validate()
Create()

DTemplateSoundScPddFactory +constructor

Ensure that the inherited data member iUnitsMask is +setup correctly according to the unit numbers to be supported. The default +version enables the PDD to open both the first playback driver channel number KSoundScTxUnit0 and +the first record driver channel number KSoundScRxUnit0:

// Support units KSoundScTxUnit0 & KSoundScRxUnit0 +iUnitsMask=(1<<KSoundScRxUnit0)|(1<<KSoundScTxUnit0);

Install()

This +is the second stage constructor for the PDD factory class. The template version +creates the DFC queue and sets the driver name.

_LIT(KSoundScPddName,"SoundSc.Template"); + +// Definitions for the kernel thread created for this sound driver. +_LIT(KSoundScDriverThreadName,"SoundDriverThread"); +const TInt KSoundScDriverThreadPriority=26; // One less than DFC thread 0 + +TInt DTemplateSoundScPddFactory::Install() +{ + TInt r=KErrNone; + if (iDfcQ==NULL) + { + // Create a new sound driver DFC queue (and associated kernel thread). + r=Kern::DynamicDfcQCreate(iDfcQ, KSoundScDriverThreadPriority, KSoundScDriverThreadName); + } + + if (r==KErrNone) + { + r=SetName(&KSoundScPddName); // Set the name of the driver object + } + return(r); + }

The physical device is identified by the driver name, +alter this to reflect your device. The driver name is the same as the LDD +name, but followed by a dot and a short string to represent the physical device. +For example, the name used for template is "SoundSc.Template ".

Validate()

This +function is called by the kernel device driver framework to see whether this +PDD is suitable for use with a particular driver channel. Ensure that the +unit number checking code is correct for the unit numbers that are to be supported. +The default version enables the PDD to open both the first playback driver +channel number KSoundScTxUnit0 and the first record driver +channel number KSoundScRxUnit0.

// Check the unit number is compatible +if (aUnit!=KSoundScTxUnit0 && aUnit!=KSoundScRxUnit0) + return(KErrNotSupported);

Create()

This +function is called by the kernel device driver framework to create a PDD object. +Ensure that the unit number checking code is correct for the unit numbers +that are to be supported. For configurations supporting both playback and +record, it must be capable of creating either a playback or record PDD object +according to the channel number specified. The template version is implemented +as follows:

TInt DTemplateSoundScPddFactory::Create(DBase*& aChannel, + TInt aUnit, + const TDesC8* /*anInfo*/, + const TVersion& /*aVer*/) + { + // Create the appropriate PDD channel object. + TInt r=KErrNoMemory; + if (aUnit==KSoundScRxUnit0) + { + // Create a record PDD channel object + DTemplateSoundScRxPdd* pD=new DTemplateSoundScRxPdd; + aChannel=pD; + if (pD) + { + pD->iPhysicalDevice=this; + r=pD->DoCreate(); + } + } + else + { + // Create a playback PDD channel object + DTemplateSoundScTxPdd* pD=new DTemplateSoundScTxPdd; + aChannel=pD; + if (pD) + { + pD->iPhysicalDevice=this; + r=pD->DoCreate(); + } + } + return(r); + }