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ID:36604988
大小:1.51 MB
页数:93页
时间:2019-05-09
《vxworks嵌入式操作系统》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、嵌入式软件VxWorks编程介绍邹昕光哈尔滨工业大学自动化测控所联系电话:86413531-609E-mail:xgzou@dsp.hit.edu.cnAgendaTaskIntertaskcommunicationISRTaskEachtaskhasitsowncontext,whichistheCPUenvironmentandsystemresourcesthatthetaskseeseachtimeitisscheduledtorunbythekernel.Atask’scontextissa
2、vedinthetaskcontrolblock(TCB).TaskAtask’scontextincludes:-athreadofexecution;thatis,thetask’sprogramcounter-theCPUregistersand(optionally)floating-pointregisters-I/Oassignmentsforstandardinput,output,anderror-adelaytimer-atime-slicetimer-kernelcontrolstr
3、uctures-signalhandlers-debuggingandperformancemonitoringvaluesTaskThedefaulttaskschedulingalgorithminwindispriority-basedpreemptivescheduling.RoundRobinisanoptionalalgorithm.Thewindkernelhas256prioritylevels,numbered0through255.Priority0isthehighestandpr
4、iority255isthelowest.TaskSchedulerControlRoutinesTaskTaskLockWhenataskdisablestheschedulerbycallingtaskLock(),nopriority-basedpreemptioncantakeplacewhilethattaskisrunning.Ifthetaskexplicitlyblocksorsuspends,theschedulerselectsthenexthighest-priorityeligi
5、bletasktoexecute.Whenthepreemption-lockedtaskunblocksandbeginsrunningagain,preemptionisagaindisabled.ThetaskLock()preventtaskcontextswitching,butdonotlockoutinterrupthandling.TaskControlRoutineTasktaskSpawnTaskNameandIDRoutinesTaskInformationRoutinesTask
6、DeletingRoutinesTaskControlRoutinesTaskHookRoutinesTaskSpawnTaskNameandIDRoutinesTaskInformationRoutinesTaskInformationRoutinesTaskDeletingRoutinesTaskDeletingRoutinesTaskControlRoutinesTaskHookRoutinesSharedCodeandReentrancyAsinglecopyofcodeexecutedbymu
7、ltipletasksiscalledsharedcode.Asubroutineisreentrantifasinglecopyoftheroutinecanbecalledfromseveraltaskcontextssimultaneouslywithoutconflict.Modifyglobalorstaticvariables.CodeReentrancySolutionsDynamicStackVariablesGuardedGlobalandStaticVariablesTaskVari
8、ablesDynamicStackVariablesGuardedGlobalandStaticVariablesProvidingamutual-exclusionmechanismtoprohibittasksfromsimultaneouslyexecutingcriticalsectionsofcode.TaskVariablesIntertaskCommunicationSharedDataStructureMutualExclu
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