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基于VxWorks的CompactPCI总线中断机制研究.docx

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基于VxWorks的CompactPCI总线中断机制研究 Introduction CompactPCIisahigh-speedopenarchitecturesystemthatutilizesthePeripheralComponentInterconnect(PCI)busstandard.Itprovidesareliableandscalableplatformforhigh-performancecomputinginvariousfieldssuchastelecommunications,industrialautomation,anddefensesystems.VxWorksisareal-timeoperatingsystemwidelyusedinCompactPCI-basedsystems.Itprovidesarobustandflexibleenvironmentfordevelopingmission-criticalapplications.Interrupt-handlingisacriticalcomponentofanyreal-timeoperatingsystem,andthispaperaimstoexploretheinterrupthandlingmechanisminVxWorks-basedCompactPCIsystems. OverviewofInterrupts InterruptsareanessentialmechanismthatallowsaCPUtorespondtoexternaleventsquickly.Whenaninterruptoccurs,theCPUpausesitscurrentprogramexecutionandswitchestoaninterrupt-handlerroutinetoservicetheinterrupt.Interruptscanbegeneratedbyvarioussources,suchashardwaredevices,softwareprograms,orexternalevents. Inareal-timesystem,interruptsmustbehandledpromptlytoavoiddatalossorcorruption.Theinterrupthandlingprocessconsistsoftwostages:interruptserviceroutine(ISR)andinterrupthandler.TheISRisresponsibleforperformingtheimmediateresponsetotheinterrupt,whilethehandlerisresponsibleformanagingandschedulingtheISR.InaVxWorks-basedCompactPCIsystem,theISRistypicallyalow-levelroutinethatperformsbasictaskssuchasacknowledgingtheinterruptandstoringanydataassociatedwiththeinterrupt.TheinterrupthandlerisresponsibleformanagingtheISRandcoordinatingtheresponseofothersystemcomponents. InterruptHandlinginVxWorks-basedCompactPCISystems InVxWorks-basedCompactPCIsystems,interruptsarehandledusingapriority-basedinterruptcontroller.Theinterruptcontrollerisresponsibleformanagingtheinterruptrequest(IRQ)signalsgeneratedbythevariousdevicesonthePCIbus.Thepriorityofthesesignalsdetermineswhichinterruptwillbeservicedfirst.TheinterruptcontrollersendstheIRQtotheCPU,whichthenforwardstheIRQtothecorrespondinginterrupt-handlerroutine. VxWorksprovidesseveralAPIfunctionstohandleinterrupts,suchasintConnect()andint