Data +Transfer between LDD and PDD

The device driver framework supplies each LDD with a pointer, DLogicalChannelBase::iPdd, +through which it can access PDD functions. The pointer is initialised by the +Kernel while creating a physical channel.

An example of this pointer +in use:

inline DExUartPhysicalChannel * DExDriverLogicalChannel::Pdd() + { return (DExUartPhysicalChannel *)iPdd; } + +// example use +Pdd()->SetDfcQ();

Similarly, a PDD can access a LDD, though +this access must be initialised by the LDD. In the following example, the +physical channel declares a pointer to a logical channel, which the LDD sets. +Callbacks to the LDD are done using this pointer.

// PDD channel class +class DExH4PhysicalChannel: public DBase + { + ... +public: + DExDriverLogicalChannel* iLdd; + } + +// Second stage constructor of Logical channel +TInt DExDriverLogicalChannel::DoCreate(TInt /*aUnit*/, const TDesC8* + /*anInfo*/, const TVersion& aVer) + { + ... + Pdd()->iLdd=this; + } + +// example use in PDD +iLdd->ReceiveDataComplete(KErrNone);

The logical channel class, DLogicalChannelBase, +also has pointers to a logical device (iDevice) and a physical +device (iPhysicalDevice). These pointers are initialised +during the driver loading and channel open operations, so they can also be +used to pass information between the LDD and PDD.

class DLogicalChannelBase: public DObject + { + ... +public: + DLogicalDevice* iDevice; + DPhysicalDevice* iPhysicalDevice; + DBase* iPdd; + } + +// example use +TDynamicDfcQue* DExUartPhysicalChannelH4::DfcQ(TInt aUnit) + { + ... + return ((DExH4PhysicalDevice*) + (iLdd->iPhysicalDevice))->iDfcQueue; + }