英语翻译Many applications written for ARM-based systems are embe

英语翻译Many applications written for ARM-based systems are embedded applications that arecontained in ROM and execute on reset.There are a number of factors that must beconsidered when writing embedded operating systems,or embedded applications thatexecute from reset without an operating system,including:• Remapping ROM to RAM,to improve execution speed.• Initializing the execution environment,such as exception vectors,stacks,I/Os.• Initializing the application.– For example,copying initialization values for initialized variables from ROMto RAM and resetting all other variables to zero.• Linking an embedded executable image to place code and data in specific locationsin memory.For an embedded application without an operating system,the code in ROM must providea way for the application to initialize itself and start executing.No automaticinitialization takes place on reset,therefore the application entry point must performsome initialization before it can call any C code.The initialization code,located at address zero after reset,must:• Mark the entry point for the initialization code.• Set up exception vectors.• Initialize the memory system.• Initialize the stack pointer registers.• Initialize any critical I/O devices.• Initialize any RAM variables required by the interrupt system.• Enable interrupts (if handled by the initialization code).• Change processor mode if necessary.• Change processor state if necessary.After the environment has been initialized,the sequence continues with the applicationinitialization and should enter the C code.大体意思就行·