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<concept id="GUID-AC560324-798C-5D0A-B23D-2419A7688A5B" xml:lang="en"><title>Channel

Implementation</title><shortdesc>Describes how to implement the physical channels with the template

port. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>A Sound Driver PDD must implement physical channels to use the audio hardware

of the phone. The main Sound Driver PDD class is derived from <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita"><apiname>DSoundScPdd</apiname></xref>.

A Sound Driver PDD that provides record and playback functions must implement

a record driver channel and a playback driver channel. </p>

<p>The template defines two classes: <codeph>DTemplateSoundScRxPdd</codeph> and <codeph>DTemplateSoundScTxPdd</codeph>,

corresponding to record and playback respectively. The classes provide default

implementations for the virtual functions defined by <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita"><apiname>DSoundScPdd</apiname></xref>,

together with a constructor and destructor, and typically need little or no

modification. </p>

<section id="GUID-61725EEB-5114-5A85-9C28-57A47F14000C"><title>PDD class constructor</title> <p>Implement

the PDD class constructor for both the playback and record driver channels.

This is normally limited to </p> <ul>

<li id="GUID-E02B0EE1-5171-5E9F-9BFE-FFAB6E15B290"><p>initialising any data

members that need values other than zero </p> </li>

<li id="GUID-4B39AEC4-0A02-5099-9805-F35B2AF4AD90"><p>initialising any DFC

call-backs added. </p> </li>

</ul> <p>Access to hardware has the potential to fail and so should be deferred

to the second stage constructor <xref href="GUID-AC560324-798C-5D0A-B23D-2419A7688A5B.dita#GUID-AC560324-798C-5D0A-B23D-2419A7688A5B/GUID-F66BF339-FCE6-5859-87D1-7A0B0ED69D84">DoCreate()</xref>. </p> </section>

<section id="GUID-CD12E6E9-C363-5CF9-91E1-694C34DE2BD9"><title>PDD class destructor</title> <p>Implement

the PDD class destructor for both the playback and record driver channels.

The destructor must release any hardware and Symbian platform resources that

have been allocated to the driver. For example, this might include: </p> <ul>

<li id="GUID-6D33C44B-B88F-504B-B750-FF010A72A290"><p>unbinding ISRs </p> </li>

<li id="GUID-9DF0D93B-6782-5E94-80EB-A806BC1AB6B9"><p>cancelling private DFCs </p> </li>

<li id="GUID-157C24A6-52F6-5BF1-BF94-035394F274F5"><p>closing DMA channels </p> </li>

<li id="GUID-47452140-FA8E-55A8-BE2D-32AC87FF215E"><p>deleting any mono-to-stereo

conversion buffers </p> </li>

</ul> <p>The template versions of this function delete each DMA request object

created in the PDD second stage constructor <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-C0CA28E4-2356-333D-B708-CBE469F1614F"><apiname>DSoundScPdd::DoCreate()</apiname></xref> and

close the DMA channel. </p> </section>

<section id="GUID-F66BF339-FCE6-5859-87D1-7A0B0ED69D84"><title>DoCreate()</title> <p>Implement

a PDD class second stage constructor for both the playback and record driver

channels. In the template version, the function <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-C0CA28E4-2356-333D-B708-CBE469F1614F"><apiname>DSoundScPdd::DoCreate()</apiname></xref> is

called from the PDD factory when a channel is opened on the device. Generally,

any hardware or Symbian platform resources required by the driver

channel should be acquired here. However, powering up the sound device should

be deferred to the <xref href="GUID-AC560324-798C-5D0A-B23D-2419A7688A5B.dita#GUID-AC560324-798C-5D0A-B23D-2419A7688A5B/GUID-B72057E6-B93C-505F-9789-83251D09B78E">PowerUp()</xref> function.

Operations performed by this function include: </p> <ul>

<li id="GUID-C3E2E6ED-14AE-52D1-9F11-618DCE7D2C1E"><p>binding an ISR to an

audio related interrupt </p> </li>

<li id="GUID-129BD014-9302-50AE-A33B-728D40DBF428"><p>open a DMA channel </p> </li>

<li id="GUID-51B51BEC-B8B8-50CF-8618-BB0B5B00F999"><p>allocate a mono-to-stereo

conversion buffer </p> </li>

</ul> <p>The template versions of this function include code to set up a DMA

channel. This involves opening a DMA channel in the appropriate direction

for the driver channel and then allocating a set of DMA request objects. However,

to use this implementation you must supply the missing platform specific information: </p> <ul>

<li id="GUID-64F62CF9-9D26-5E39-A632-39DF91AB1E98"><p>Provide values for the

maximum number of DMA requests outstanding on the DMA channel. These values

determine the number of separate DMA request objects allocated for the DMA

channel, and so the number of transfer fragments that the PDD can accept from

the LDD at any time. See <xref href="GUID-15FDDEED-89F1-5BE5-97AD-8DFD3640369A.dita">playback</xref> and <xref href="GUID-4AEF7595-17C0-513E-9568-B212E6194388.dita">record</xref>. </p> </li>

<li id="GUID-60C86EBD-B26F-501D-B7D5-CE113D4368C0"><p>Set the appropriate

DMA values for your device within the file <filepath>soundsc_plat.h</filepath>.

These values, renamed in section <xref href="GUID-C6ABE2CA-901E-55F1-9837-7018A1612BCF.dita">copying

the template port implementation</xref> to reflect your device name, are <codeph>KTemplateMaxTxDmaRequests</codeph> or <codeph>KTemplateMaxRxDmaRequests</codeph> for playback and record respectively. </p> </li>

<li id="GUID-BBF4F320-22A7-54AE-ACD1-6C10138F5031"><p>Setup the DMA channel

information for the device. This includes the following members of <xref href="GUID-83882548-FAC5-3EFF-92ED-14D1D9A85D37.dita#GUID-83882548-FAC5-3EFF-92ED-14D1D9A85D37/GUID-6B973278-8BE7-3CE5-97D8-60E8D3F4D473"><apiname>TDmaChannel::SCreateInfo</apiname></xref>. </p> <ul>

<li id="GUID-084CF2BA-308D-5F32-9BC2-C5B39DEC497B"><p> <codeph>iCookie</codeph>:

The platform specific ID used by the DMA controller to select the DMA channel

to open. </p> </li>

<li id="GUID-7EE1F596-9FB5-5C29-8130-097CE6129F91"><p> <codeph>iDesCount</codeph>:

The number of DMA descriptors the DMA controller should create. This is typically

set with the same value as <codeph>KTemplateMaxTxDmaRequests</codeph> or <codeph>KTemplateMaxRxDmaRequests</codeph>. </p> </li>

<li id="GUID-0B12DDF1-AC34-5592-AC55-E0363C60449A"><p> <codeph>iDfcQ</codeph>:

The DFC queue to use to service DMA interrupts. This should point to the same

DFC queue that is returned to the LDD for client request handling. See the <xref href="GUID-AC560324-798C-5D0A-B23D-2419A7688A5B.dita#GUID-AC560324-798C-5D0A-B23D-2419A7688A5B/GUID-32C77B77-76CE-54AE-B791-28A7DD309A7D">DfcQ()</xref> section. </p> </li>

<li id="GUID-AE4E59DD-4FBB-54A8-BE79-F4138AB34D5C"><p> <codeph>iDfcPriority</codeph>:

The DFC priority. This should be set to a higher value than that used by the

LDD for handling client requests. For example, higher than one. </p> </li>

</ul> </li>

</ul> </section>

<section id="GUID-32C77B77-76CE-54AE-B791-28A7DD309A7D"><title>DfcQ()</title> <p>Make

sure that the template version of the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-C41B9733-BE86-3CF1-83A7-150EC9D35249"><apiname>DSoundScPdd::DfcQ()</apiname></xref> function

is appropriate for your configuration. This function has the following signature: </p> <codeblock id="GUID-28E301B7-C032-5F6E-BCA7-A6D20FC541EA" xml:space="preserve">TDfcQue* DfcQ()</codeblock> <p>The

supplied implementation is as follows </p> <codeblock id="GUID-D95DC9F9-C68A-50E2-ADA6-8D1268A18147" xml:space="preserve">TDfcQue* DTemplateSoundScTxPdd::DfcQ()

    {

    return(iPhysicalDevice->iDfcQPtr);

    }</codeblock> <p>Many requests are executed in the context of a kernel-side

thread. Rather than assign a kernel thread for the driver in the LDD, the

Sound Driver allows the PDD to specify the DFC thread returned via the <xref href="GUID-71190437-912E-3E23-8E68-4FA8FF913D7A.dita"><apiname>DfcQ()</apiname></xref> function,

which it calls when the driver channel is opened. </p> <p>The default implementation

for the record and playback driver channels, returns a pointer to the DFC

queue created by the PDD factory class. </p> <p>See also <xref href="GUID-1138D29D-2EC5-59DF-9AA7-2D863FBC024F.dita">Implementing

the PDD factory</xref>  </p> </section>

<section id="GUID-B549F062-061D-5876-AB43-AC10C62477EE"><title>GetChunkCreateInfo()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-9F845935-A6AA-320B-AF09-F121F95C44B2"><apiname>DSoundScPdd::GetChunkCreateInfo()</apiname></xref> function for both

the playback and record driver channels. This function has the following signature: </p> <codeblock id="GUID-934D39E5-5DDE-5165-BCED-255CA6D0B0F2" xml:space="preserve">void DSoundScPdd::GetChunkCreateInfo(TChunkCreateInfo&amp; aChunkCreateInfo)</codeblock> <p>The

supplied implementation is as follows: </p> <codeblock id="GUID-47334636-5E5D-59CF-A894-62747DD648BD" xml:space="preserve">void DTemplateSoundScTxPdd::GetChunkCreateInfo(TChunkCreateInfo&amp; aChunkCreateInfo)

    {

    __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::GetChunkCreateInfo"));

    // TO DO: (mandatory)

    // Setup the shared chunk create information in aChunkCreateInfo for this play device.

    aChunkCreateInfo.iType=TChunkCreateInfo::ESharedKernelMultiple;

    // aChunkCreateInfo.iMapAttr=???

    aChunkCreateInfo.iOwnsMemory=ETrue;                 // Using RAM pages.

    aChunkCreateInfo.iDestroyedDfc=NULL;                // No chunk destroy DFC.

    }</codeblock> <p>The PDD must initialise the <xref href="GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4.dita"><apiname>TChunkCreateInfo</apiname></xref> object

with the information that defines the characteristics of the shared chunk

required for the audio device. This function is called by the LDD just before

it creates a shared chunk for the channel, in response to an <xref href="GUID-B0118EDD-2B08-353E-BE92-2DC75E5622B3.dita#GUID-B0118EDD-2B08-353E-BE92-2DC75E5622B3/GUID-1978D84C-6E2A-39C0-AF5F-17C85E5B25B4"><apiname>RSoundSc::SetBufferChunkCreate()</apiname></xref> request

from the client. </p> <p>Values for the following data members must be supplied

by the PDD: </p> <ul>

<li id="GUID-10F7ED98-299F-5D90-A7EC-85BD97BBECEF"><p> <xref href="GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4.dita#GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4/GUID-4384AF76-CECE-3B86-BE92-375C1DEA36DA"><apiname>TChunkCreateInfo::iType</apiname></xref>  </p> </li>

<li id="GUID-10159693-8680-5CD7-88C8-A967DDC53024"><p> <xref href="GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4.dita#GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4/GUID-4D355352-04CA-34D2-B1F4-684E07E7DDE9"><apiname>TChunkCreateInfo::iMapAttr</apiname></xref>  </p> </li>

<li id="GUID-06459B1A-5D5A-5013-912D-0C52E7FD398A"><p> <xref href="GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4.dita#GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4/GUID-106850A0-5498-387F-AF70-F9D04EB6318D"><apiname>TChunkCreateInfo::iOwnsMemory</apiname></xref>  </p> </li>

<li id="GUID-D8DE49EB-04D5-50BA-8CEA-7EFFA7584A74"><p> <xref href="GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4.dita#GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4/GUID-58271733-146A-3ECB-91AC-C38BD2ADC9A0"><apiname>TChunkCreateInfo::iDestroyedDfc</apiname></xref>  </p> </li>

</ul> <p>The data member <xref href="GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4.dita#GUID-51F7DBCF-BFB6-31F9-8882-5D263A1AD4B4/GUID-3BE6D452-84D0-3E80-8238-7A9114A89ED5"><apiname>TChunkCreateInfo::iMaxSize</apiname></xref> is

calculated by the LDD so there is no need to define it. </p> <p>See <xref href="GUID-51514A4B-0220-557B-9F7A-FB110CEFEF10.dita">How to share chunks</xref>. </p> </section>

<section id="GUID-9D4D9F06-8C88-51C1-9E29-D0B95B523A8D"><title>Caps()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-B80B86C6-696A-37AA-9ACD-2BC76B88762C"><apiname>DSoundScPdd::Caps()</apiname></xref> function for both the playback

and record driver channels. The function has the following signature: </p> <codeblock id="GUID-8306A135-350C-5F8D-B51D-F8A2EED41244" xml:space="preserve">void DSoundScPdd::Caps(TDes8&amp; aCapsBuf) const</codeblock> <p>The

supplied implementation is as follows: </p> <codeblock id="GUID-27BE7DD7-D42B-54BA-AC77-1201C1F09F68" xml:space="preserve">void DTemplateSoundScTxPdd::Caps(TDes8&amp; aCapsBuf) const

    {

    __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::Caps"));

    // Copy iCaps back.

    TPtrC8 ptr((const TUint8*)&iCaps,sizeof(iCaps));

    aCapsBuf.FillZ(aCapsBuf.MaxLength());

    aCapsBuf=ptr.Left(Min(ptr.Length(),aCapsBuf.MaxLength()));      

    }</codeblock> <p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita"><apiname>TSoundFormatsSupportedV02</apiname></xref> is the

main audio capabilities class. The PDD must fill this object with the capabilities

for the particular audio device. the LDD uses this to get the play or record

capabilities of a particular sound device once a driver channel to the device

has been opened. </p> <p>Values for the following variables must be supplied

by the PDD: </p> <ul>

<li id="GUID-2F03F186-D9AF-5431-B3F8-D3B794352208"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-1FE2868A-1823-308A-B1C9-2DAD557F6F3A"><apiname>TSoundFormatsSupportedV02::iDirection</apiname></xref>  </p> <ul>

<li id="GUID-053B114E-2A52-53FD-912F-F8FF890601C4"><p> <xref href="GUID-AF772B74-0D5F-3270-BA61-2503BA5DFE6B.dita"><apiname>ESoundDirRecord</apiname></xref>  </p> </li>

<li id="GUID-CEADC6F1-6016-5AB1-9349-EEFB63EF26AA"><p> <xref href="GUID-708043EB-5ED5-3923-B41A-321AD7DF3D8C.dita"><apiname>ESoundDirPlayback</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-95FC1D2B-BBFB-52DC-ADE3-BA980E7E46F3"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-75B0E2F7-44BE-3A97-B482-E1CB29D9F2E5"><apiname>TSoundFormatsSupportedV02::iChannels</apiname></xref>  </p> <ul>

<li id="GUID-998425C3-E73B-5DB4-94F8-10BDCFBBE779"><p> <xref href="GUID-65BCF594-59A1-335F-AADB-1920E7AD3F71.dita"><apiname>KSoundMonoChannel</apiname></xref>  </p> </li>

<li id="GUID-7D5EE578-16AC-56A0-B064-6000F5A9C2DF"><p> <xref href="GUID-4E63CE9C-C604-3B2C-993D-9A0502A39064.dita"><apiname>KSoundStereoChannel</apiname></xref>  </p> </li>

<li id="GUID-0C17CB17-7452-5A1A-B76D-75A57960BDE8"><p> <xref href="GUID-30E8F803-39E1-3F53-AB5A-3B593BC1D69F.dita"><apiname>KSoundThreeChannel</apiname></xref>  </p> </li>

<li id="GUID-E1DE0CD0-DD63-5140-A5C5-7141A5E9632D"><p> <xref href="GUID-BD021640-3457-3721-9DF1-A15EE8A874AC.dita"><apiname>KSoundFourChannel</apiname></xref>  </p> </li>

<li id="GUID-E59E9D5E-F360-52FD-A0D0-C7CDAE5593DC"><p> <xref href="GUID-3E3B5485-F69B-3ECC-A0A4-12183444E61F.dita"><apiname>KSoundFiveChannel</apiname></xref>  </p> </li>

<li id="GUID-56DD5098-0C0C-5175-B375-766FE628C359"><p> <xref href="GUID-83C9F5FE-DE44-3940-B738-BD4486293C39.dita"><apiname>KSoundSixChannel</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-A6847CF6-48DC-510E-BCFF-33E7E5FB0161"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-1F79E9BB-BF7C-31AD-AA0C-A85748F4231A"><apiname>TSoundFormatsSupportedV02::iRates</apiname></xref>  </p> <ul>

<li id="GUID-99377F03-BA89-5DB0-AC4D-5F8892EB1F65"><p> <xref href="GUID-F98BADA5-852B-3859-B74A-B9747F79A754.dita"><apiname>KSoundRate7350Hz</apiname></xref>  </p> </li>

<li id="GUID-99FFC99B-740B-5809-9C75-C8CC1157F4E3"><p> <xref href="GUID-47512813-5787-3328-9980-399AA782E6A2.dita"><apiname>KSoundRate8000Hz</apiname></xref>  </p> </li>

<li id="GUID-D2C75BB5-5D8B-556B-A5BF-6A8C24D07D74"><p> <xref href="GUID-A622C93B-DF18-359D-B74A-0F90695900B7.dita"><apiname>KSoundRate8820Hz</apiname></xref>  </p> </li>

<li id="GUID-83D98EBD-AD0E-588E-8CFD-59B44C22FE6A"><p> <xref href="GUID-165180AC-1227-30BF-97DA-860C3AC3AA4E.dita"><apiname>KSoundRate9600Hz</apiname></xref>  </p> </li>

<li id="GUID-8D99D6B7-7FA7-5B8A-BEB9-2D982273C201"><p> <xref href="GUID-8DF1D395-4AC1-38AA-9F6A-C8867B1F4A60.dita"><apiname>KSoundRate11025Hz</apiname></xref>  </p> </li>

<li id="GUID-98353A3A-EFAC-5B6C-A779-8F12BB9150BA"><p> <xref href="GUID-512150A4-0796-3016-9CBC-83117E2930ED.dita"><apiname>KSoundRate12000Hz</apiname></xref>  </p> </li>

<li id="GUID-C27DD198-13FA-522A-9079-0BAA37094E16"><p> <xref href="GUID-892B4698-4914-348B-AB88-A1AC33D1E5EE.dita"><apiname>KSoundRate14700Hz</apiname></xref>  </p> </li>

<li id="GUID-71087DE2-06A9-536A-94DF-74FFFCB2F0DF"><p> <xref href="GUID-1A199051-5D76-396B-AA44-89506A128BFF.dita"><apiname>KSoundRate16000Hz</apiname></xref>  </p> </li>

<li id="GUID-666FA027-30AF-593B-894B-443B5C57E2DF"><p> <xref href="GUID-4021CE80-6667-36BB-9839-583E84AB9E83.dita"><apiname>KSoundRate22050Hz</apiname></xref>  </p> </li>

<li id="GUID-9D0D7E14-1FBE-5C80-A108-D3903D57ED49"><p> <xref href="GUID-73C38AA3-92AD-3EF0-BF60-3A207CD29C0E.dita"><apiname>KSoundRate24000Hz</apiname></xref>  </p> </li>

<li id="GUID-721DCA57-6E9B-5B02-9EA4-7640C652C5CE"><p> <xref href="GUID-9092C33B-C406-3044-AC8F-885F3EAE8B86.dita"><apiname>KSoundRate29400Hz</apiname></xref>  </p> </li>

<li id="GUID-5362CD78-1981-559B-9E1B-C999CDC8E3D9"><p> <xref href="GUID-0237DB93-3C16-3DCF-836E-CDECE95EAB1E.dita"><apiname>KSoundRate32000Hz</apiname></xref>  </p> </li>

<li id="GUID-61D0A788-2160-538F-82DB-414E6A34EC97"><p> <xref href="GUID-D3045D52-3092-3CCA-9AA5-05DE1ACAB92C.dita"><apiname>KSoundRate44100Hz</apiname></xref>  </p> </li>

<li id="GUID-28474DAC-AD25-506B-9112-F56825F845D2"><p> <xref href="GUID-DBD2AD6A-79F9-3D94-B6CB-1ED1E45F401A.dita"><apiname>KSoundRate48000Hz</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-CB112345-C035-5F7E-9AE5-B5222FF4F0A9"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-21F664A7-046E-3B1F-8C0B-A8B0EC0EC16C"><apiname>TSoundFormatsSupportedV02::iEncodings</apiname></xref>  </p> <ul>

<li id="GUID-F5833DD3-D273-5B62-9F4B-FEEC51D8CDF2"><p> <xref href="GUID-5BE58F42-47B2-3EB8-9F3B-DEF019C79499.dita"><apiname>KSoundEncodings8BitPCM</apiname></xref>  </p> </li>

<li id="GUID-B58CB616-CDCD-5CD0-AEC4-622F5AAB2474"><p> <xref href="GUID-790BA733-2B34-33B2-BF7B-7113DB1856A6.dita"><apiname>KSoundEncodings16BitPCM</apiname></xref>  </p> </li>

<li id="GUID-A4019328-CC8B-5224-8808-F3822230C389"><p> <xref href="GUID-EAB5A509-B0D6-3E2F-8106-D87A7C9D504F.dita"><apiname>KSoundEncodings24BitPCM</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-52DDB751-925B-5CC5-81F9-6F65A9D2039E"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-7950BC29-5C2E-34E0-B037-DDDDE0261DB7"><apiname>TSoundFormatsSupportedV02::iDataFormats</apiname></xref>  </p> <ul>

<li id="GUID-AD7EA560-7914-5D9D-B548-14DB3FA4AC7A"><p> <xref href="GUID-E02D661C-430F-306F-BD12-42238A91D83A.dita"><apiname>KSoundDataFormatInterleaved</apiname></xref>  </p> </li>

<li id="GUID-36EAAA69-B18A-555A-9646-FB8F6EC66505"><p> <xref href="GUID-ACC09AC6-A29B-3926-8AE4-4DA60416A3C1.dita"><apiname>KSoundDataFormatNonInterleaved</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-905CC707-760B-52F3-A942-0ADA02B69FA8"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-6F2D37B3-C465-3C77-A861-7FF9061F8EB9"><apiname>TSoundFormatsSupportedV02::iRequestMinSize</apiname></xref>  </p> </li>

<li id="GUID-8FCD4F3E-F70F-5E1B-8952-B667DC9D4AD2"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-472BCD65-11CE-3AEE-8DAE-9E56523AC096"><apiname>TSoundFormatsSupportedV02::iRequestAlignment</apiname></xref>  </p> </li>

<li id="GUID-749CE201-0554-5202-ABFC-FF9C0C4B1C1A"><p> <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita#GUID-39915413-31A6-360F-9758-5DBDF9D70103/GUID-AB35243B-ECD9-3268-A6FF-5079D1A45EA0"><apiname>TSoundFormatsSupportedV02::iHwConfigNotificationSupport</apiname></xref> </p> </li>

</ul> <p>Many of the attribute ranges are passed as bit settings, and can

assume all the values independently of one another. </p> <p>The following

is a portion of the <xref href="GUID-161BA615-FD2C-3A7E-992E-FBBED621CBBB.dita"><apiname>Caps()</apiname></xref> function for the template port

for the playback path of the AC97 Controller Unit (UCB140) codec device. </p> <p>The

PDD maintains a <xref href="GUID-39915413-31A6-360F-9758-5DBDF9D70103.dita"><apiname>TSoundFormatsSupportedV02</apiname></xref> object as one

of its data members named <codeph>iCaps</codeph>. The contents of <codeph>iCaps</codeph> is

copied into the descriptor and passed as an argument to the <xref href="GUID-161BA615-FD2C-3A7E-992E-FBBED621CBBB.dita"><apiname>Caps()</apiname></xref> function: </p> <codeblock id="GUID-21B70DCD-7133-53A1-AE5C-848E0F68DF43" xml:space="preserve">void DTemplateSoundScTxPdd::Caps(TDes8&amp; aCapsBuf) const

    {

     __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::Caps"));

     // Copy iCaps back.

     TPtrC8 ptr((const TUint8*)&iCaps,sizeof(iCaps));

     aCapsBuf.FillZ(aCapsBuf.MaxLength());

     aCapsBuf=ptr.Left(Min(ptr.Length(),aCapsBuf.MaxLength()));        

    }

</codeblock> <p>The data member <codeph>iCaps</codeph> is initialised by the

function <xref href="GUID-681FB26E-0027-38E6-88A1-9E9046011312.dita"><apiname>SetCaps()</apiname></xref> called from the second stage constructor

of the PDD object: </p> <codeblock id="GUID-B17BA93D-14D6-56A9-8F1F-9FFEF88559D3" xml:space="preserve">void DTemplateSoundScTxPdd::SetCaps()

    {

     __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::SetCaps"));

     // The data transfer direction for this unit is play.

     iCaps.iDirection=ESoundDirPlayback;

     // TO DO: (mandatory)

     // Setup the rest of the capabilities structure DTemplateSoundScTxPdd::iCaps with the capabilities of this

     // audio playback device.

    }</codeblock> </section>

<section id="GUID-A2A7A6FF-8F46-589D-B5D6-E33ED3FF0692"><title>MaxTransferLen()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-534D46F4-2CB1-3130-9E72-A1C3BF085865"><apiname>DSoundScPdd::MaxTransferLen()</apiname></xref> function for both playback

and record driver channels. The function has the following signature: </p> <codeblock id="GUID-039E8EF1-AA13-5C38-92DD-46AFC8E1E8F3" xml:space="preserve">TInt DSoundScPdd::MaxTransferLen() const</codeblock> <p>The

supplied implementation is as follows: </p> <codeblock id="GUID-E27E52F5-175A-5264-8B08-AE0BDAD5B495" xml:space="preserve">TInt DTemplateSoundScTxPdd::MaxTransferLen() const

    {

    return(KTemplateMaxTxDmaTransferLen);

    }</codeblock> <p>This function is called each time the LDD alters the

audio configuration of the channel. For example, after calling <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-39AA2B2D-E98B-33A0-9C46-08B783413860"><apiname>DSoundScPdd::SetConfig()</apiname></xref>.

The LDD uses the value returned to fragment record and playback data transfers

so that they are manageable by the PDD. See <xref href="GUID-15FDDEED-89F1-5BE5-97AD-8DFD3640369A.dita">playback</xref> and <xref href="GUID-4AEF7595-17C0-513E-9568-B212E6194388.dita">record</xref>. </p> <p>The

value returned by <xref href="GUID-615DF55C-EC50-3BF0-9C46-AB24E9505C5E.dita"><apiname>MaxTransferLen()</apiname></xref> is not as important

for PDDs that use the Symbian DMA framework because the DMA framework handles

fragmentation. </p> <p>If the PDD has to employ mono-to-stereo data conversion

using a conversion buffer when configured in mono mode, then it needs to return

the value that corresponds with the size of the conversion buffer each time

it is configured in mono mode. See <xref href="GUID-E2641957-8163-5EF4-B282-FC3FD9CA75A6.dita#GUID-E2641957-8163-5EF4-B282-FC3FD9CA75A6/GUID-5C66667B-55C0-521D-86E3-67593DB381C9">mono

to stereo conversion</xref>. </p> </section>

<section id="GUID-B72057E6-B93C-505F-9789-83251D09B78E"><title>PowerUp()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-6301A4AA-CC41-3DBC-A349-9BD5C9B01276"><apiname>DSoundScPdd::PowerUp</apiname></xref> function for both the playback

and record driver channels. The function has the following signature: </p> <codeblock id="GUID-F9706BE3-125F-56B3-947E-3534FB3A5D23" xml:space="preserve">TInt DSoundScPdd::PowerUp()</codeblock> <p>The

supplied implementation is as follows: </p> <codeblock id="GUID-DB986B0B-CC10-5842-BB54-76683A35EB38" xml:space="preserve">TInt DTemplateSoundScTxPdd::PowerUp()

    {

    // TO DO: (mandatory)

    // Power up the audio device.

    return(KErrNone);

    }</codeblock> <p>This function initialises the codec device and any associated

controller hardware that allows the CPU to communicate with it. However, at

this stage only basic initialisation of these hardware components is required,

as the specific audio configuration has not yet been specified, and data transfer

has not yet started. </p> <p>If the PDD supports both record and playback

driver channels then most, if not all, of this hardware initialisation is

common to both channels. It may be necessary to ensure that such initialisation

on one channel cannot interfere with the other. For example, when calling <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-1B2E2F89-75A8-3740-893A-4DCDB0A350D3"><apiname>DSoundScPdd::PowerUp()</apiname></xref> on

the record driver channel while the playback driver channel is active, make

sure that it does not interfere with audio playback. This typically requires

hardware status information to be held in the PDD factory object that is common

to both channels. </p> </section>

<section id="GUID-3764C238-A458-5D13-8AB2-EE53CA91F6E5"><title>SetConfig()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-39AA2B2D-E98B-33A0-9C46-08B783413860"><apiname>DSoundScPdd::SetConfig()</apiname></xref> function for both playback

and record driver channels. The function has the following signature: </p> <codeblock id="GUID-DB782F12-E5CE-5D13-8C12-8E57AB47BDB4" xml:space="preserve">TInt DSoundScPdd::SetConfig(const TDesC8&amp; aConfigBuf)</codeblock> <codeblock id="GUID-868A3301-3CAD-5077-88AC-2A2A6C125AFD" xml:space="preserve">TInt DTemplateSoundScTxPdd::SetConfig(const TDesC8&amp; aConfigBuf)

    {

    __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::SetConfig"));

    // Read the new configuration from the LDD.

    TCurrentSoundFormatV02 config;

    TPtr8 ptr((TUint8*)&config,sizeof(config));

    Kern::InfoCopy(ptr,aConfigBuf);

    // TO DO: (mandatory)

    // Apply the specified audio configuration to the audio device.

    TInt r=KErrNone;

    __KTRACE_SND(Kern::Printf("<DTemplateSoundScTxPdd::SetConfig - %d",r));

    return(r);

    }</codeblock> <p>A configuration buffer in a packaged <xref href="GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68.dita"><apiname>TCurrentSoundFormatV02</apiname></xref> object

containing the new configuration settings. </p> <ul>

<li id="GUID-2D88064E-2258-55FA-BE68-831889E9E2C8"><p> <xref href="GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68.dita#GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68/GUID-AE4EDE94-5902-3D73-BAE4-4A49B3E3CC6C"><apiname>TCurrentSoundFormatV02::iChannels</apiname></xref>  </p> </li>

<li id="GUID-CBACC0C9-1C73-59E0-BAA4-63110DECDED9"><p> <xref href="GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68.dita#GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68/GUID-FA39A28F-4B0C-3B89-AB4B-763E0369AD31"><apiname>TCurrentSoundFormatV02::iRate</apiname></xref>  </p> <ul>

<li id="GUID-00FD1F5A-7941-5ED8-9878-69EDAE03F630"><p> <xref href="GUID-306655BD-FD24-37CE-8F67-F6BC5FBAA455.dita"><apiname>ESoundRate7350Hz</apiname></xref>  </p> </li>

<li id="GUID-3BEB74D8-B829-5B49-A740-F4BC0597E389"><p> <xref href="GUID-F6D595E9-BE6E-3D5F-AEEF-57FEBA5D165F.dita"><apiname>ESoundRate8000Hz</apiname></xref>  </p> </li>

<li id="GUID-E077B1A6-A625-55C8-8587-96EF7242C5F0"><p> <xref href="GUID-256AD4BA-8D30-38B8-8AC3-A63AFDCDF82E.dita"><apiname>ESoundRate8820Hz</apiname></xref>  </p> </li>

<li id="GUID-5664E1E2-DBC3-5F2C-A5BD-3EE5512C254E"><p> <xref href="GUID-3A48C172-FEEF-3A5A-A986-E5C1FD8E5048.dita"><apiname>ESoundRate9600Hz</apiname></xref>  </p> </li>

<li id="GUID-7E607F76-3975-591F-AEE3-D4CBC2B0F003"><p> <xref href="GUID-0B13D3F1-57D0-3741-BCC8-3E3BE50B59DE.dita"><apiname>ESoundRate11025Hz</apiname></xref>  </p> </li>

<li id="GUID-8054CF86-27CF-531A-9233-C6602BB958EF"><p> <xref href="GUID-88C3603E-D69F-3DE9-9AA0-F6F724432C76.dita"><apiname>ESoundRate12000Hz</apiname></xref>  </p> </li>

<li id="GUID-1AD1415C-0D0D-508F-B63E-69B553AA4109"><p> <xref href="GUID-D49E0BA6-AB68-334A-BECF-7221996C71CF.dita"><apiname>ESoundRate14700Hz</apiname></xref>  </p> </li>

<li id="GUID-1D23B890-0AFC-5E2B-8D00-E56CF1E75D07"><p> <xref href="GUID-6FDDFE56-B32E-3DA1-8E90-DCAE1476A75F.dita"><apiname>ESoundRate16000Hz</apiname></xref>  </p> </li>

<li id="GUID-A2637B2C-AD6B-5A87-86AC-FDB56DBF46C0"><p> <xref href="GUID-86882923-4DB3-3461-AF9E-D36BF75125AB.dita"><apiname>ESoundRate22050Hz</apiname></xref>  </p> </li>

<li id="GUID-8682C600-A7C8-5B8B-9824-DD670812C598"><p> <xref href="GUID-2E1FC700-5B43-39DE-8B67-7DADD38B55A5.dita"><apiname>ESoundRate24000Hz</apiname></xref>  </p> </li>

<li id="GUID-51A42D66-5B71-5325-90B7-B5A1503F21C5"><p> <xref href="GUID-244A1091-0F4A-376B-AE3E-93F09029ECF0.dita"><apiname>ESoundRate29400Hz</apiname></xref>  </p> </li>

<li id="GUID-04621385-220C-587B-9C59-68115E251D8C"><p> <xref href="GUID-1C1526A2-4BA2-3296-BBE0-152070B43EE9.dita"><apiname>ESoundRate32000Hz</apiname></xref>  </p> </li>

<li id="GUID-5DECBAD3-09E7-5967-82B3-7C923F870DA6"><p> <xref href="GUID-028FCDA8-E1FC-3E5D-827B-E4513991C1F2.dita"><apiname>ESoundRate44100Hz</apiname></xref>  </p> </li>

<li id="GUID-27AA4D39-3CA5-52A0-9F97-C8543AAECB97"><p> <xref href="GUID-14D9C50A-2F72-3D1D-A15B-BDE4FAA33ED8.dita"><apiname>ESoundRate48000Hz</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-95DDDF4C-B70E-56B1-92E6-616ADCB45025"><p> <xref href="GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68.dita#GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68/GUID-1A4256A2-A2FE-3FD0-8849-A9F37E1D7A77"><apiname>TCurrentSoundFormatV02::iEncoding</apiname></xref>  </p> <ul>

<li id="GUID-48484A2E-6970-59AE-9CD5-C93BE349C28D"><p> <xref href="GUID-866386CC-C9CA-3029-95C2-800F6B6C3C2D.dita"><apiname>ESoundEncoding8BitPCM</apiname></xref>  </p> </li>

<li id="GUID-357130A0-C112-5803-A4D3-9B1237B5931C"><p> <xref href="GUID-E69FCDC5-9A22-3C5A-89C9-A7B869744948.dita"><apiname>ESoundEncoding16BitPCM</apiname></xref>  </p> </li>

<li id="GUID-E2920329-BDFC-5B28-BF53-F4CF45DBE9AC"><p> <xref href="GUID-289CBD4B-ACEF-3A43-8935-201635AC658F.dita"><apiname>ESoundEncoding24BitPCM</apiname></xref>  </p> </li>

</ul> </li>

<li id="GUID-406F8EE9-885D-5569-98E0-A473BB7462FB"><p> <xref href="GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68.dita#GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68/GUID-3A9546CB-33D6-3171-A8F7-0E642EB8E798"><apiname>TCurrentSoundFormatV02::iDataformat</apiname></xref>  </p> <ul>

<li id="GUID-D21416A0-3E78-5D5C-BFE3-0C8A75F80429"><p> <xref href="GUID-5ADC3C98-2D05-35E1-96D2-42B3A65BF25F.dita"><apiname>ESoundDateFormatInterleaved</apiname></xref>  </p> </li>

<li id="GUID-1A7EC2CC-D94F-514E-BB8A-9A3B3551B13F"><p> <xref href="GUID-352ED2EF-C98C-305E-80F1-FE30DF1BE4CA.dita"><apiname>ESoundDateFormatNonInterleaved</apiname></xref>  </p> </li>

</ul> </li>

</ul> <p>The PDD must read and locally save the contents of the <xref href="GUID-EF1D41AB-929D-3E51-98AA-F175DDB58F68.dita"><apiname>TCurrentSoundFormatV02</apiname></xref> configuration

object that has been passed as a descriptor from the LDD. The template version

contains the following code to achieve this: </p> <codeblock id="GUID-7FF5383E-FAE0-51A7-8E9E-0F489D841C72" xml:space="preserve">// Read the new configuration from the LDD.

TCurrentSoundFormatV02 config;

TPtr8 ptr((TUint8*)&config, sizeof(config));

Kern::InfoCopy(ptr, aConfigBuf);</codeblock> <p>It is not necessary to check

for configurations requested by the LDD that are not supported by the audio

hardware device if the <xref href="GUID-161BA615-FD2C-3A7E-992E-FBBED621CBBB.dita"><apiname>Caps()</apiname></xref> function has been implemented

correctly by the PDD. This is because the LDD rejects such audio configuration

requests from the client. However, if the PDD supports both playback and record

driver channels then it needs to check that the specified configuration does

not conflict with one already in use by the other channel. </p> <p>The PDD

sets up the audio hardware device according to the audio configuration specified

if it is required. Some, if not all of this hardware configuration may be

put off until data transfer is started, this is when <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-54D3CC19-0C00-3FFA-BD1A-62618D36EB20"><apiname>DSoundScPdd::StartTransfer()</apiname></xref> is

called, so for now the PDD needs to save the configuration. </p> <p>If the

PDD has to employ mono-to-stereo conversion of data using a conversion buffer

while the audio configuration is set to mono, then the memory for the conversion

buffer should be allocated at this time. </p> </section>

<section id="GUID-51420A2F-180B-5916-AF5A-685ABD156A2D"><title>SetVolume()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-3C56E870-1F05-31BC-B799-AF49F77E2930"><apiname>DSoundScPdd::SetVolume</apiname></xref> function for both the playback

and record driver channels. This has the following signature: </p> <codeblock id="GUID-6FEA0876-7753-54C7-A414-9A54913F1778" xml:space="preserve">TInt DSoundScPdd::SetVolume(TInt aVolume)</codeblock> <p>The

supplied implementation is as follows: </p> <codeblock id="GUID-14196DC5-8630-5E06-869A-D9A5EE423BF6" xml:space="preserve">TInt DTemplateSoundScTxPdd::SetVolume(TInt aVolume)

    {

    __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::SetVolume"));

    // TO DO: (mandatory)

    // Set the specified play volume on the audio device.

    TInt r=KErrNone;

    return(r);

    }</codeblock> <p>The PDD must first convert the volume/record level information

specified into a form which can be used to program the hardware. This may

require converting the value from a gain factor to an attenuation factor and/or

applying a scaling factor. The LDD detects situations where the client specifies

a record level /volume that is already in effect, and in this case does not

unnecessarily call the PDD. </p> <p>The PDD may opt to setup the audio hardware

device within this function or it may defer this until data transfer is started

with the function <xref href="GUID-CCACE58D-8884-37A4-B7DB-F1DFDEE4A8F1.dita#GUID-CCACE58D-8884-37A4-B7DB-F1DFDEE4A8F1/GUID-788592C9-FCCA-3E34-BEA7-5DC5E6A497C8"><apiname>DSOundScPdd::StartTransfer()</apiname></xref>. For PDDs

which support both record and playback driver channels, it is normal for audio

devices to allow the record and playback gains to be programmed independently,

this means that checking for conflicts between the channels is rarely required

for this function. </p> </section>

<section id="GUID-287BB55C-E0FD-5214-9FAA-857AB46C64ED"><title>StartTransfer()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-66F3D9DA-F61F-3C1D-8C95-02C7C561AE64"><apiname>DSoundScPdd::StartTransfer</apiname></xref> function for both the playback

and record driver channels. This has the following signature: </p> <codeblock id="GUID-02F7B0B7-35A7-525C-A88D-6555113D6D62" xml:space="preserve">TInt DSoundScPdd::StartTransfer()</codeblock> <p>The

supplied implementation is as follows: </p> <codeblock id="GUID-DE7BF31A-B5D4-5348-9280-0C326D37DAF8" xml:space="preserve">TInt DTemplateSoundScTxPdd::StartTransfer()

    {

    __KTRACE_SND(Kern::Printf(">DTemplateSoundScTxPdd::StartTransfer"));

    // TO DO: (mandatory)

    // Prepare the audio device for playback.

    TInt r=KErrNone;

    __KTRACE_SND(Kern::Printf("<DTemplateSoundScTxPdd::StartTransfer - %d",r));

    return(r);

    }</codeblock> <p>This function performs any configurations of the audio

hardware device that were deferred from the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-39AA2B2D-E98B-33A0-9C46-08B783413860"><apiname>DSoundScPdd::SetConfig()</apiname></xref> function.

These configurations may include start-up of the DMA engine, enabling any

interrupts related to audio transfer and interrupts that detect error conditions,

for example. At this stage, no data has yet been supplied to the device for

transfer as the function <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-8C79D09B-317A-3D8E-B9C2-474812F17529"><apiname>DSoundScPdd::TransferData()</apiname></xref> has

not yet been called. </p> <p>If the PDD supports both record and playback

driver channels then it may be necessary to ensure that such hardware configuration

on one channel cannot interfere with the other. </p> </section>

<section id="GUID-5E29637F-140F-5F1B-B969-DF9682CEF5E2"><title>TransferData()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-EF749829-6C35-3954-A48D-483FD0182CC9"><apiname>DSoundScPdd::TransferData</apiname></xref> function for both playback

and record driver channels. This has the following signature: </p> <codeblock id="GUID-F13C3C46-D208-5E24-B986-3A32FAFBE453" xml:space="preserve">TInt DSoundScPdd::TransferData(TUint aTransferID,TLinAddr aLinAddr,

                               TPhysAddr aPhysAddr,TInt aNumBytes)</codeblock> <p>Once

transfer has been started by calling <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-54D3CC19-0C00-3FFA-BD1A-62618D36EB20"><apiname>DSoundScPdd::StartTransfer()</apiname></xref>,

the function <xref href="GUID-209D8909-56BD-3601-98C4-FB6E004D78EE.dita"><apiname>TransferData</apiname></xref> is called repeatedly by the LDD

for the transfer of each fragment. See the <xref href="GUID-15FDDEED-89F1-5BE5-97AD-8DFD3640369A.dita">playback</xref> and <xref href="GUID-4AEF7595-17C0-513E-9568-B212E6194388.dita">record</xref> sections for

details. </p> <p>The template version for the record driver channel contains

the following code: </p> <codeblock id="GUID-C86982D4-A2FE-5904-A46C-D52D349D018E" xml:space="preserve">TInt DTemplateSoundScRxPdd::TransferData(TUint aTransferID, TLinAddr aLinAddr,

                                         TPhysAddr /*aPhysAddr*/, TInt aNumBytes)

    {  

    TInt r=KErrNone;

    // Check that we can accept the request

    if (iPendingRecord>=KTemplateMaxRxDmaRequests)

        r=KErrNotReady;

    else

        {

        // Start a DMA transfer.

        iDmaRequest[iFlag]->iTransferID=aTransferID;

        iDmaRequest[iFlag]->iTransferSize=aNumBytes;

        // TO DO: (mandatory)

        // Supply the DMA source information.

        TUint32 src=0; // ???

        r=iDmaRequest[iFlag]->Fragment(src,aLinAddr,aNumBytes,KDmaMemDest|KDmaIncDest,0);

        if (r==KErrNone)

            {

            iDmaRequest[iFlag]->Queue();

            iPendingRecord++;

            if ((++iFlag)>=KTemplateMaxRxDmaRequests)

                iFlag=0;

            // TO DO: (mandatory)

            // Start the audio device transferring data.

            }

        }

    return(r);

    }</codeblock> <p><note> The template version used by the playback function

is very similar. </note></p> <p>The first step is for the PDD to check that

it has the capacity to accept a further transfer. For example, check that

the PDD has a DMA request object that is free and that the DMA controller

has the capacity for another transfer to be queued. If the PDD does not have

the capacity to accept another transfer then it should immediately return <xref href="GUID-51298FCE-7857-39F8-BFAB-49AF5556D0CC.dita"><apiname>KErrNotReady</apiname></xref> to

signal this. </p> <p>Otherwise, the PDD can start a DMA transfer. To do this

it must acquire a DMA request object. The class <xref href="GUID-6B0DB695-9033-3F85-AC3A-1867E99BE2BD.dita"><apiname>DTemplateSoundScRxDmaRequest</apiname></xref> is

the abstraction for a DMA record request and is defined as follows: </p> <codeblock id="GUID-04B1D7FD-4E17-5CD0-974F-A3A1BCB04C58" xml:space="preserve">/** Wrapper function for a shared chunk sound driver record DMA request. */

class DTemplateSoundScRxDmaRequest : public DDmaRequest

    {

public:  

    DTemplateSoundScRxDmaRequest(TDmaChannel& aChannel, DTemplateSoundScRxPdd* aPdd,

                                 TInt aMaxTransferSize=0);

    static void DmaService(TResult aResult, TAny* aArg);

public:

    /** Pointer back to the PDD. */

    DTemplateSoundScRxPdd* iPdd;

    /** The transfer ID for this DMA request - supplied by the LDD. */

    TUint iTransferID;

    /** The transfer sizes in progress. */

    TUint iTransferSize;

    };

    This is derived from DDmaRequest the base class

    for a DMA request.</codeblock> <p>The data member <codeph>iPdd</codeph> is

a pointer to the owning PDD object. This is used within the member function <xref href="GUID-8B538AA6-9489-309F-8756-2474310CD5DA.dita"><apiname>DmaService()</apiname></xref> which

is the DMA callback function, and is called when the DMA request has been

completed by the DMA framework. The data member <codeph>iTransferID</codeph> is

a value supplied by the LDD which it uses to identify the transfer fragment.

The PDD must save this value and pass it back to the LDD when the transfer

is completed. Similarly, the member <codeph>iTransferSize</codeph> is used

to hold the length of the transfer fragment in bytes. If the transfer is successful

then this value is also passed back to the LDD to allow it to maintain its

count of bytes recorded. </p> <p>The record PDD class owns an array of DMA

request objects: </p> <codeblock id="GUID-8314BE9B-2D19-585F-B44E-17C8529CEFEF" xml:space="preserve">/** The DMA request structures used for transfers. */             

DTemplateSoundScRxDmaRequest* iDmaRequest[KTemplateMaxRxDmaRequests];</codeblock> <p>It

also owns the data member <codeph>iFlag</codeph>, which always holds the number

for the next DMA request that should be used for transfer. Before starting

the DMA transfer, setup the appropriate DMA request object with the transfer

ID and the transfer length. </p> <codeblock id="GUID-2F4CB025-C2E2-52DD-A679-CF1DCC3677FA" xml:space="preserve">/** A flag selecting the next DMA request for transfer. */

TInt iFlag;</codeblock> <p>Next the function <xref href="GUID-780F4D53-5546-3B69-B328-0226C70EBDE2.dita#GUID-780F4D53-5546-3B69-B328-0226C70EBDE2/GUID-B14B0478-80D6-3F5E-88B6-1676411D9CF2"><apiname>DDmaRequest::Fragment()</apiname></xref> is

called to specify the details of the transfer to the DMA framework and to

allow it to analyse this. Here the appropriate platform specific 32-bit DMA

source identifier, <codeph>src</codeph>, needs to be supplied. The template

driver shown previously specifies the destination memory address as a linear

address but the physical address may be used instead. Both forms of this address

are passed as arguments to the <xref href="GUID-34E7FF1F-091A-3C45-B83A-AEB64E2AD286.dita"><apiname>TransferData()</apiname></xref> function. </p> <p>If

fragmentation is successful then the request object is queued on the DMA channel <xref href="GUID-780F4D53-5546-3B69-B328-0226C70EBDE2.dita#GUID-780F4D53-5546-3B69-B328-0226C70EBDE2/GUID-0A83F782-DB62-39ED-8D32-DBD5949C8D3F"><apiname>DDmaRequest::Queue()</apiname></xref> and

the value of <codeph>iFlag</codeph> is updated ready for the next transfer.

The PDD class also keeps a count of the number of transfer fragments outstanding

by incrementing the variable <codeph>iPendingRecord</codeph>: </p> <codeblock id="GUID-5C738134-0683-5FAB-8733-29D9A336402F" xml:space="preserve">/** The number of outstanding DMA record requests on the DMA channel. */   

TInt iPendingRecord;</codeblock> <p>The final part of this function requires

platform specific code to start the audio hardware device transferring data.

This needs to be executed for each fragment transferred or just for the first

fragment queued following the <xref href="GUID-FE6DE994-719C-3900-B4A0-009914697380.dita"><apiname>StartTransfer()</apiname></xref> function. </p> <p>Once

the transfer is complete, either successfully or with an error, the DMA framework

executes the static DMA callback function, <xref href="GUID-6B0DB695-9033-3F85-AC3A-1867E99BE2BD.dita#GUID-6B0DB695-9033-3F85-AC3A-1867E99BE2BD/GUID-E12BA027-3D58-30A8-A9F7-B7B7DC55D0D5"><apiname>DTemplateSoundScRxDmaRequest::DmaService()</apiname></xref>,

as follows: </p> <codeblock id="GUID-2ED07474-F489-5545-9FB6-BC229C00D4F3" xml:space="preserve">/**

DMA rx service routine. Called in the sound thread's DFC context by the s/w DMA controller.

@param aResult Status of DMA transfer.

@param aArg Argument passed to DMA controller.

*/ 

void DTemplateSoundScRxDmaRequest::DmaService(TResult aResult, TAny* aArg)

    {

    DTemplateSoundScRxDmaRequest& req=*(DTemplateSoundScRxDmaRequest*)aArg;

    TInt res=KErrNone;

    TInt bytesTransferred=req.iTransferSize;

    if (aResult!=DDmaRequest::EOk)

        {

        res=KErrCorrupt;

        bytesTransferred=0;

        }

    // Inform the LDD of the result of the transfer.

    req.iPdd->RecordCallback(req.iTransferID,res,bytesTransferred);   

    return;

    }</codeblock> <p>This function receives two arguments: </p> <ul>

<li id="GUID-7D4D15BD-3BA0-5899-B67E-C7F24F548D22"><p>the result of the transfer

from the DMA framework </p> </li>

<li id="GUID-FE18B3C9-A3B3-5599-8CC6-66977D0FA56A"><p>an argument supplied

to the DMA framework when the request object was created </p> </li>

</ul> <p>In this specific case, the argument type is a pointer to the DMA

request object, and allows the retrieval of the transfer ID and the transfer

size. In the template driver version an unsuccessful transfer returns an error

value of <xref href="GUID-253F06EA-F14E-3A8E-BA4C-8E787B5F0670.dita"><apiname>KErrCorrupt</apiname></xref> with a transfer byte count of zero. </p> <p>From

the callback function we call the record PDD function to decrement the count

of transfer fragments outstanding and to inform the LDD of the completion

of transfer. </p> <codeblock id="GUID-69C81D24-D725-51B2-8099-1D089A70AE00" xml:space="preserve">void DTemplateSoundScRxPdd::RecordCallback(TUint aTransferID, TInt aTransferResult,TInt aBytesTransferred)

    {

    iPendingRecord--;

    Ldd()->RecordCallback(aTransferID,aTransferResult,aBytesTransferred);

    } 

</codeblock> </section>

<section id="GUID-E9B63AC5-4AED-53E3-B7CA-21AACE04FC37"><title>StopTransfer()</title> <p>Implement

the <xref href="GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424.dita#GUID-61CC68CB-A01D-3CA0-93D9-F3717ABD6424/GUID-7C629A7C-0C64-32AB-8159-A4075DEEF544"><apiname>DSoundScPdd::StopTransfer</apiname></xref> function for both the play

and record driver channels. This has the following signature: </p> <codeblock id="GUID-E56EFFEC-59CA-595F-BFA8-72299999DD05" xml:space="preserve">void DSoundScPdd::StopTransfer()</codeblock> <p>The

PDD must reverse any operation performed on the audio hardware device done

as part of <xref href="GUID-FE6DE994-719C-3900-B4A0-009914697380.dita"><apiname>StartTransfer()</apiname></xref> or <xref href="GUID-34E7FF1F-091A-3C45-B83A-AEB64E2AD286.dita"><apiname>TransferData()</apiname></xref>.

This includes stopping the audio hardware device from transferring data and