Research On Interrupt Processing Mechanism Of Embedded System Based On Deterministic Finite Automaton

The interrupts are indispensable constituent in computer systems. In input/output processing, multichannel procedure, time-sharing operation, real-time processing of man-machine interface, accident processing, surveillance and track of procedures and in multi-processor systems, interrupts play a key role. An embedded system is able to perform without the support of an operating system, but the interrupt processing all there is no place not in. When an embedded system is actually in use, massive interrupt processing of amounts of interrupt signals triggered by outside interrupt sources is required. The signals, in most situations, are disordered, whereas completing of each task,asks for an ordered interrupt sequence composed by a set of interrupt signals. This kind of situation is called complex interrupt. As the existing interruption mechanism is facing vital challengs when dealing with the complex interruption., a more effective and stable interruption mechanism which is able to handle disordered and complex interrupt requests with efficiency will add huge flexibility to designing and using of embedded systems, thus enhance the working efficiency of the systems.In this paper, we target on solutions to reasonably schedule and orderly process disordered interruption signals that an embedded system received,.mainly analyzed traditional interrupt processing ways in SCMs and external interrupt controllers. We also studied the interruption processing mechanism in Linux operating system. At last, we proposed an interruption mechanism based on DFA (Deterministic Finite Automaton), which without support for multi-task operating system embedded in the system how to make a number of tasks can be orderly implementation and without the interruption of disorder signal interference.This mechanism adopted a two-step approach to get interruption signals as many as possible, then it sequentially scheduled the received signals according to working principles of DFA. In this way, we are able to deal with disordered complex interrupt requests.In Chapter2, we focused on interrupt mechanisms workig in embedded systems without support of an operating system. In this kind of embedded system, interrupt processing solely rely on the processing power of CPU or the capacity of interrupt controller. When facing complex interruptions, the system is very vulnerable to logic confusions, leading to system malfunction or even system crash. Complex interruptions also cause great distress for designers.In Chapter3, we talk about interrupt processing in Linux, including initialization process of the interruption, hardware handling of interruptions and abnormities, interrupt process and Linux soft interrupt mechanism. Some code about the interruption in Linux system is also discussed in this chapter.In the fourth chapter, we proposed a new interruption mechanism based on DFA. The new mechanism is mainly used in embedded systems without support of an operating system. The interruption mechanism introduced DFA working principles which enabled orderly completion of various tasks by disorder interruption signals managed under DFA, thus multi-tasking is better supported in actual application.