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9 --> |
10 <!DOCTYPE concept |
10 <!DOCTYPE concept |
11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
11 PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd"> |
12 <concept xml:lang="en" id="GUID-FE3825C5-BDEE-5F18-9FFD-2E794E618FEC"><title>Data Access Example</title><shortdesc>This example describes typical processing of the data in an RMBufChain. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><section><title>Downwards flow</title> <fig id="GUID-43219AE7-A0E4-570A-98ED-07D44D849979"><title> |
12 <concept xml:lang="en" id="GUID-FE3825C5-BDEE-5F18-9FFD-2E794E618FEC"><title>Data Access Example</title><shortdesc>This example describes typical processing of the data in an RMBufChain. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody><section><title>Downwards flow</title> <fig id="GUID-43219AE7-A0E4-570A-98ED-07D44D849979"><title> |
13 Example : flow going downwards |
13 Example : flow going downwards |
14 </title> <image href="GUID-30987768-8B0A-5A35-820C-DBB410D2053B_d0e113991_href.png" placement="inline"/></fig> <p>The following function is a simplified example of how a component in the middle of the stack could process data sent to the driver. As shown in the above diagram, the upper layer provides the data in the <codeph>RMBufChain</codeph> parameter. </p> <codeblock id="GUID-4C87CEB3-DCFD-5765-BF89-6EF9275EB584" xml:space="preserve"> |
14 </title> <image href="GUID-30987768-8B0A-5A35-820C-DBB410D2053B_d0e107453_href.png" placement="inline"/></fig> <p>The following function is a simplified example of how a component in the middle of the stack could process data sent to the driver. As shown in the above diagram, the upper layer provides the data in the <codeph>RMBufChain</codeph> parameter. </p> <codeblock id="GUID-4C87CEB3-DCFD-5765-BF89-6EF9275EB584" xml:space="preserve"> |
15 void Send (RMBufChain &aChain) |
15 void Send (RMBufChain &aChain) |
16 { |
16 { |
17 TBuf8<KHeaderLength> aHeader; |
17 TBuf8<KHeaderLength> aHeader; |
18 |
18 |
19 // [...] fill the header |
19 // [...] fill the header |
27 // send the updated chain to the next layer |
27 // send the updated chain to the next layer |
28 downwardComponent->Send(aChain); |
28 downwardComponent->Send(aChain); |
29 } |
29 } |
30 </codeblock> <p>Note that depending on the available space remaining in front of the data in the MBuf, the <xref href="GUID-F024208C-ED19-3301-85C1-53F397C9910F.dita#GUID-F024208C-ED19-3301-85C1-53F397C9910F/GUID-A7CEF452-AB4E-378C-A262-B1C5FCBA68BB"><apiname>RMBufChain::Prepend()</apiname></xref> method may request the pond to add a new MBuf to the front of the chain. For more information, see <xref href="GUID-B4F15CA3-CAD4-5A87-9610-A656CA337B72.dita#GUID-B4F15CA3-CAD4-5A87-9610-A656CA337B72/GUID-5EBCD46C-5E07-5DB1-90D9-6A5CA3E36C0B">Buffer layout</xref>. </p> </section> <section><title>Upwards flow</title> <fig id="GUID-402331EB-6DE8-5DC5-9FF7-7D5DD8D816D5"><title> |
30 </codeblock> <p>Note that depending on the available space remaining in front of the data in the MBuf, the <xref href="GUID-F024208C-ED19-3301-85C1-53F397C9910F.dita#GUID-F024208C-ED19-3301-85C1-53F397C9910F/GUID-A7CEF452-AB4E-378C-A262-B1C5FCBA68BB"><apiname>RMBufChain::Prepend()</apiname></xref> method may request the pond to add a new MBuf to the front of the chain. For more information, see <xref href="GUID-B4F15CA3-CAD4-5A87-9610-A656CA337B72.dita#GUID-B4F15CA3-CAD4-5A87-9610-A656CA337B72/GUID-5EBCD46C-5E07-5DB1-90D9-6A5CA3E36C0B">Buffer layout</xref>. </p> </section> <section><title>Upwards flow</title> <fig id="GUID-402331EB-6DE8-5DC5-9FF7-7D5DD8D816D5"><title> |
31 Example : flow going upwards |
31 Example : flow going upwards |
32 </title> <image href="GUID-11CBC0BA-3683-584A-9DC9-8BD3C9573F01_d0e114021_href.png" placement="inline"/></fig> <p>The following function is a simplified example of how a component in the middle of the stack could process data received by the driver. As shown in the above diagram, the underlying layer provides the data in the <codeph>RMBufChain</codeph> parameter. </p> <codeblock id="GUID-C36656D9-AEB0-5DBF-A469-0183F80AE057" xml:space="preserve"> |
32 </title> <image href="GUID-11CBC0BA-3683-584A-9DC9-8BD3C9573F01_d0e107483_href.png" placement="inline"/></fig> <p>The following function is a simplified example of how a component in the middle of the stack could process data received by the driver. As shown in the above diagram, the underlying layer provides the data in the <codeph>RMBufChain</codeph> parameter. </p> <codeblock id="GUID-C36656D9-AEB0-5DBF-A469-0183F80AE057" xml:space="preserve"> |
33 void Process (RMBufChain &aChain) |
33 void Process (RMBufChain &aChain) |
34 { |
34 { |
35 TBuf8<KHeaderLength> aHeader; |
35 TBuf8<KHeaderLength> aHeader; |
36 |
36 |
37 // get a copy of the header |
37 // get a copy of the header |