Architecture

diff -r 578be2adaf3e -r 307f4279f433 Adaptation/GUID-ACA48BEE-FE73-5C47-B022-E50728CEDBEE.dita --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Adaptation/GUID-ACA48BEE-FE73-5C47-B022-E50728CEDBEE.dita Fri Oct 15 14:32:18 2010 +0100 @@ -0,0 +1,55 @@ + + + + + +ArchitectureDescribes the architecture of the Sound Driver. +

There are three main parts:

the user side interface +to the Driver +channel. This is an instance of a class derived from RSoundSc.

The +class RSoundSc provides the user side interface to the +driver. This class is defined in \e32\include\d32soundsc.h. +An instance of RSoundSc is required for each driver channel opened by the client. When opening a driver channel, the client specifies a channel number for the audio +channel. Channel numbers 0 to 3 are allocated for output/playback channels +and channels 4 to 7 are allocated for input/record channels.
the driver channel, also known as the logical channel or LDD.

The +class DSoundScLdd is the logical +channel object for either audio playback or record. This class is defined +in \e32\include\drivers\soundsc.h. An instance of DSoundScLdd is +created for each driver +channel opened. The driver implements play and record operation over +a single audio hardware device as two separate units. Therefore, a client that needs to issue both record and playback requests +has to open two separate driver +channels.

DSOundScLdd is derived from DLogicalChannel. DLogicalChannel is +the base class for a logical channel and provides the framework in which user +side client requests are normally executed in the context of a kernel side +thread. However, for this particular driver, not every request is executed +in the context of a kernel thread. Requests that do not require access to +hardware are handled in the context of the calling thread.
the physical +channel, also known as the PDD, manages access to the audio hardware +device for all instances of the driver +channel.

The class DSoundScPdd is the base +class for the Sound Driver PDD object. This class is used for either playback +or record, it implements the platform specific layer of the driver and an +instance of this class is created for each driver +channel opened. This is created by the Sound Driver physical device +class DSoundScPddFactory when a channel is opened. The +class DSoundScPdd is defined in \e32\include\drivers\soundsc.h.

The +following diagram illustrates the Sound Driver architecture. The interactions +between the user side and kernel side classes are shown.

+ + The main classes involved in Sound Driver implementation. + + + + \ No newline at end of file