Improvement Of Scheduling Algorithms And Realization Of Internet Protocol Stack Based On Embedded Operation System

With the increasing combination of Embedded system and the network, introducing TCP/IP protocol stack to support the connection of embedded device to the network has become an important research topic in embedded field. Under the circumstance of network service, Real-time embedded operation system may have to process real-time tasks, and provide certain internet service. For real-time tasks, they should be done according to the sequence of priority; for non-real-time tasks, they are expected to be done in turn. Therefore, the appointment of proper scheduling strategy is especially important. UC/OS-II is a preemptive kernel embedded operation system whose source code is opened. It includes only basic functions, such as tasks scheduling, tasks management, time management, memory management and the communication and synchronization between tasks. It doesn't provide those extra service like I/O management, file system and network. Because of the translatability and openness of uC/OS-II, users can add the required services by themselves. In order to satisfy the requirement of the network service in the Real-time embedded system,on the basis of uC/OS-II, the improvement of its task scheduling algorithm function has been made according to the characteristic of kernel priority distribution. On the aspect of the operation system, improvement has been done on kernel process scheduling and Nbuf allocation to realize the round-robin between processes. But as a whole, the priority scheduling mode is preserved. In the function for distributing memory buffer, the allocation of Nbuf resources has been done by the addition of certain signal. On the aspect of TCP/IP protocol stack,according to the characteristic of uC/OS-II operation system,Internet stack model are proposed considering the memory size occupied by embedded system. The main work has been done on the edit and rewriting of the resource code to realize the basic function of TCP/IP protocol. The main data structure, and data flow process, and relative system function are listed in order to realize the basic protocol function of internet.