Embedded File System Design And Implementation

With the development of the embedded technology and the lower price of the hardware , the storage ability of the embedded system improve rapidly. There're so many complicated data resources need to be manage that the importance of the embedded file system become more and more prominent.Unlike the general file system, the embedded file system is based on the kernel of the real time operation system. The design of the embedded file system should not only satisfy all kinds of requirement needed by data storage but also reduce the negative impact on the whole system caused by the adding of file system. This demands the exploration of the coupling mechanism between the file system and the kernel on the fundamental of the research on both of them. This work is focused on the research of the real time response, transplantable, reducible and configurable of the file system.Embedded file system CEFS is developed on the basis of the real time operation system CRTOSII. The CEFS is implemented using the technology of the IMPS and the FAT bitmap which is a wildly used file system format. The CEFS can be divided into three levels: the drivers of the devices, the management of the Cache and the kernel of the file system. The CEFS also have provided the POSIX API Interface.In order to support different file systems without perceiving by users, the CEFS provides only a group of API to users. The kernel of the file system is composed of two parts: the virtual file system and the specialized format file systems. The virtual file system provides the unified API to users. The CEFS hasimplemented two specialized format file systems-the IMFS and the FAT, whichis under the level of the virtual file system. The IMFS is a UNIX similar file system based on the memory and the FAT is based on the Flash Memory.This thesis analyzes the main characters of the architecture of the CEFS, the design plan and the implementation technology in detail.