Design And Implementation For Embedded Operating System Based On OSEK/VDX Standard

The number of microprocessors in automotive vehicle is increasing rapidly since the first microprocessor was embedded into electronic control system of the engine.Now, there are more than seventy microprocessors in some automotive vehicles,so the software system of the vehicles is becoming complicated and software engineers have to spend a lot of time on developing and debugging it, this brings about the duplicated development in automotive software and inefficiency of software engineer.To solve these problems,the OSEK/VDX standards were constituted by European automobile industry for the purpose of a standard embedded and distributed operating system used not only in automotive industry but also in other fileds.Standard interfaces of embedded operating system, communication and network management were defined.The standards can improve the reusability and compatibility of the automotive electronic software,avoid the duplicated development and accelerate the software development.So it is of greate significance to research OSEK/VDX standards.Domestic research on OSEK/ VDX rose in recent years.Mechanism of the OSEK/VDX is analysed first in the dissertation according to the OSEK/ VDX operating system specification. Its architecture,task manage- ment, event mechanism,resource management, interrupt mechanism and alarm mechanism are analysed in detail.Then the key data structures and system calls of task management,event mechanism,resource management,interrupt mechamism and alarm mechanism are designed and implemented on the basis of former analysis.Next,some optimizations are proposed to met the problems in the process of design and development.A ready table is designed to manage the tasks of the operating system where there is only one task per priority and it reduce the time of searching the task with highest priority to a constant time;As there is no need to save the context when terminating a task,different task switch policies are provided:general task switch and the task switch when terminating a task;As only wait single event system call is provided,the function of event mechanism is enhanced by provided the wait multievent system call;Interrupt service routine will happen on the stack of task in default,thus every task should reserve memory to support the nest interrupts,the single interrupt stack is provided for the nest interrupts to reduce the memory requirement of entire system.At last,the transportation of the OSEK/ VDX operating system is researched.Test applications are designed based on transportation on the 80X86 to prove the correctness of the design and implementation.The space and time performance indicators are provided on the 80X86 platform.