英语翻译

ManyapplicationswrittenforARM-basedsystemsareembeddedapplicationsthatare

containedinROMandexecuteonreset.Thereareanumberoffactorsthatmustbe

consideredwhenwritingembeddedoperatingsystems,orembeddedapplicationsthat

executefromresetwithoutanoperatingsystem,including:

•RemappingROMtoRAM,toimproveexecutionspeed.

•Initializingtheexecutionenvironment,suchasexceptionvectors,stacks,I/Os.

•Initializingtheapplication.

–Forexample,copyinginitializationvaluesforinitializedvariablesfromROM

toRAMandresettingallothervariablestozero.

•Linkinganembeddedexecutableimagetoplacecodeanddatainspecificlocations

inmemory.

Foranembeddedapplicationwithoutanoperatingsystem,thecodeinROMmustprovide

awayfortheapplicationtoinitializeitselfandstartexecuting.Noautomatic

initializationtakesplaceonreset,thereforetheapplicationentrypointmustperform

someinitializationbeforeitcancallanyCcode.

Theinitializationcode,locatedataddresszeroafterreset,must:

•Marktheentrypointfortheinitializationcode.

•Setupexceptionvectors.

•Initializethememorysystem.

•Initializethestackpointerregisters.

•InitializeanycriticalI/Odevices.

•InitializeanyRAMvariablesrequiredbytheinterruptsystem.

•Enableinterrupts(ifhandledbytheinitializationcode).

•Changeprocessormodeifnecessary.

•Changeprocessorstateifnecessary.

Aftertheenvironmenthasbeeninitialized,thesequencecontinueswiththeapplication

initializationandshouldentertheCcode.

大体意思就行·