嵌入式操作系统设计

《嵌入式操作系统设计》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、EmbeddedOperatingSystemdesignEmbeddedSystemsSummaryFormfactorPowerWeightconstraintsApplicationspecificReal-timeReliabilitySafetyArchitectureofHardwareEmbeddedOperatingsystemRequirementsandFeaturesMultitaskingScalabilityRealtimeReliabilitySafetyMultitaskingScalabilityRealtimeInreal-timesystems,co

2、rrectnessimpliesnotonlylogicalcorrectnessoftheresults,butthetimeatwhichtheresultsareproducedisimportant.Hardreal-timetasksFirmreal-timetasksSoftreal-timetasksAhardreal-timetaskisonethatisconstrainedtoproduceitsresultswithincertainpredefinedtimebounds.Thesystemisconsideredtohavefailedwheneveranyo

3、fitshardreal-timetasksdoesnotproduceitsrequiredresultsbeforethespecifiedtimebound.Everyfirmreal-timetaskisassociatedwithsomepredefineddeadlinebeforewhichitisrequiredtoproduceitsresults.However,unlikeahardreal-timetask,evenwhenafirmreal-timetaskdoesnotcompletewithinitsdeadline,thesystemdoesnotfai

4、l.Thelateresultsaremerelydiscarded.Softreal-timetasksalsohavetimeboundsassociatedwiththem,However,unlikehardandfirmreal-timetasks,thetimingconstrainsonsoftreal-timetasksarenotexpressedasabsolutevalues.Instead,theconstrainsareexpressedeitherintermsoftheaverageresponsetimesrequired.Real-timeoperat

5、ingsystemmustbefastandpredictable.Interruptlatency:Interruptlatencyisthetimedifferencebetweenadeviceraisinganinterruptandthecorrespondinghandlerbeingcalled.ISRduration:thetimeneededbyaninterrupthandlertoexecute.Schedulerlatency:Schedulerlatencyistheamountoftimethatelapsesbetweentheinterruptservi

6、ceroutinecompletingandtheschedulingfunctionbeingrun.Schedulerduration:Thisisthetimetakenbytheschedulerfunctiontoselectthenexttasktorunandcontextswitchtoit.ServicesofEmbeddedOSpSOSOSEK/VDX(ISO17356)Services参数作用说明ActivateTaskTaskID激活任务。TerminateTaskVoid终止任务。任务由运行变为挂起态。ChainTaskTaskID任务链。调用该函数的任务本身

7、终止，然后激活TaskID指定的任务。ScheduleVoid调度函数。GetTaskIDTaskID获得当前运行任务的TaskIDGetTaskStateTaskID，State获得TaskID任务的状态。Services参数作用说明GetResourceResID获取资源。ReleaseResourceResID释放资源。Services参数作用说明SetEventTaskID，Mask设置事件。ClearEventMask清除事件。Get