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<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept id="GUID-8FA1B2B0-5842-4D5D-BD61-C2D79B56ADC6" xml:lang="en"><title>Interrupt Service Routine (ISR)</title><shortdesc>This document describes interrupt service routines as used by device

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

<p>An ISR is a static function that will be executed when an interrupt occurs

on the interrupt source bound to the ISR. </p>

<codeblock id="GUID-E8416619-9314-5420-8EC1-F8BF804230DF" xml:space="preserve">// Interrupt service routines

static void UartIsr(TAny* aParam);

</codeblock>

<p>An ISR performs the actions necessary to service the event of the peripheral

that generated the interrupt and to remove the condition that caused it to

interrupt. It queues a DFC to do the required processing. It disables the

interrupts and FIQs on ARM, if required, to handle the interrupt, and enables

them before leaving. It can also disable the source of the interrupt that

it is servicing. </p>

</conbody></concept>