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<concept id="GUID-A26A3F76-54C8-5D0C-80AF-63EC9C81C050" xml:lang="en"><title>Interrupt

Dispatcher</title><shortdesc/><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This is a list of the major differences between EKA1 and EKA2: </p>

<ul>

<li id="GUID-E745D0ED-DA8A-5941-B847-593CC05FAA34"><p>In EKA1, the generic

kernel provided the code for binding and unbinding interrupts, and for maintaining

a table of ISRs in the generic kernel. This was done through functions in

the <codeph>TInterrupt</codeph> class, which no longer exists in EKA2. </p> <p>In

EKA2, this is all implemented in the port </p> </li>

<li id="GUID-777735EF-7836-52E1-8D4E-63EB8270CD2D"><p>In EKA1, is was possible

to bind multiple interrupt service routines to a single interrupt source through

a call to the <codeph>TInterrupt::Bind()</codeph> function and specifying

the appropriate value of <codeph>TBindBehaviour</codeph>. </p> <p>In EKA2,

only one ISR per interrupt source is permitted. </p> </li>

<li id="GUID-7468FC40-E348-5DA6-AD22-84C2B5164E70"><p>In EKA1, ISRs were implementations

of the <codeph>TInterrupt::Service()</codeph> function, defined as pure virtual

in <codeph>TInterrupt</codeph>. </p> <p>In EKA2, an ISR is a bare function,

not a class member. The functions for enabling, disabling and clearing interrupts

are now defined in a single, static, class called <xref href="GUID-E7A7083C-97B9-39B9-A147-4A6E314EE3A3.dita"><apiname>Interrupt</apiname></xref>.

Symbian platform defines this class, but does not provide a default implementation;

instead, the port must provide an implementation, and this is invariably in

the ASSP layer. </p> </li>

<li id="GUID-D7A41BEF-206B-5E50-BB26-59E204954E09"><p>In EKA1, interrupts

were identified by a text string defined in the ASSP layer and had to be translated

by the layer into a vector number that indexed into the interrupt vector table. </p> <p>In

EKA2, interrupts are now identified by a simple <xref href="GUID-7A2A43EC-6125-3BFE-834B-23C37F7B40D5.dita"><apiname>TInt</apiname></xref> value

defined by the port. </p> </li>

<li id="GUID-B990CB6C-856D-5B2F-BE9E-D75D898E2E60"><p>In EKA1, it was difficult

to implement support for chained, pseudo or external variant interrupts. </p> <p>In

EKA2, it is much easier because you can bind an ISR that is itself a dispatcher. </p> </li>

<li id="GUID-ED0FAE44-6396-578E-A4D4-D4B881BFB009"><p>IN EKA1, there was no

clear policy for dealing with spurious interrupts. Any spurious interrupt

would be consumed and an attempt made to disable it in hardware. </p> <p>In

EKA2, all interrupt sources are, by default, bound to the spurious interrupts

handler, which is intended to raise a panic so that spurious interrupts are

not overlooked during testing. </p> </li>

</ul>

</conbody></concept>