计算机专业毕业设计翻译--分析与设计基于嵌入式启动加载器的电动助力向系统(编辑修改稿)

计算机专业毕业设计翻译--分析与设计基于嵌入式启动加载器的电动助力向系统(编辑修改稿)内容摘要：

tocol on development workstation, and OEMPreDownload( ) can obtain an IP address through DHCP, otherwise, it would assign a static address. OEMPreDownload( ) calls EbootInitEtherTransport( ) to perform the major initialization of the work. 5) DownloadImage: Programmer should not modify the DownloadImage( ) function which is in the BLCommon library. The function has nothing to do with the medium of transport. DownloadImage( ) could download a single .bin file, multiBin, multibin packet, or the .nb0 files. The function passes back the image start address and length to the OEM code (OEMLaunch). If the downloading address is a flash memory address, DownloadImage( ) calls the OEM function to burn the image to flash. DownloadImage( ) function calls the Download Function and flash function as the following figure 12 [4] 6) OEMLaunch: the OEMLaunch function collects postdownload connection information from Platform Builder and jumps to the newly downloaded boot loader image. OEMLaunch( ) is the last boot loader function called out of BLCommon library and is responsible for jumping to and launching the runtime image. The tasks that the OEMLaunch( ) function needs to perform are shown as the follows: OEMLaunch( ) can use the EbootWaitForHostConnect( ) function which is defined in to get information about what services to start and from which ports to start the services. Check the arguments returned from EbootWaitForHostConnect( ) and then save the port or IP information. Jump to the first instruction specified by the DwLaunchAddr parameter, which is the boot loader image. 7) OEMReadData: this function reads data from the transport during the download process. 8) OEMShowProgress: this function shows visual information, on a LED, for example, to let users know that the download is in progress. It is called as the download progress [5]. 9) OEMMapMemAddr: this function handles downloads that are destined for flash. OEMMapMemAddr remaps a flashresident address to a unique RAMbased address so that flash memory OS images can be temporarily cached in RAM while the download occurs. This provides enough time to handle the flash memory update while not stalling the download process because the flash memory operation typically takes more time than the download process. 10) OEMIsFlashAddr: this function determines whether the address provided lies in a platform39。 s flash memory or RAM address range. Based on the results of this call, the OS image being downloaded might be destined for flash memory. In that case, it might need to be handled differently, for example, by providing a RAMbased file cache area to support downloading while a flash memory update takes place. 11) OEMWriteFlash: this function writes to flash memory the OS image that might be stored in a RAM file cache area. 12) OEMStartEraseFlash: called when the download process begins, and provides the overall runtime image start address and total runtime image length. The runtime image start address and total runtime image length specify the overall flash memory address range to be erased for the new runtime image. 13) OEMFinishEraseFlash: called after the runtime image is pletely downloaded and allows the boot loader to finish all flash memory erase operations. 14) OEMContinueEraseFlash: called on every runtime image .bin record download to allow the boot loader to continue the flash memory erase operation. 4. Realization of Boot Loader Boot Loader is prised of library supplied by Microsoft, Eboot, OEM functions. The library must not be modified, Possibly the Eboot need to be written, and the OEM function need to be written by programmer. The OEM function is prised of two kind of function, one is required function, the other is optional function. BLCommon library calls the required function directly. Usually BLCommon calls the optional OEM function with the point, and the point is empty in the initialization state, if the optional OEM function is called, the point would be evaluated [6]. . Required OEM function 1) Control flow functions: This functions are called by the BootloaderMain( ) function to control the executable flow of the Boot Loader. 2) Debug functions: The main task that the Debug functions perform is to transport some information, and it would track the executable of the function, municate with user simultaneity. 3) Download function: The download function is called as the Boot Loader download the operating system image. 4) Flash function: If the boot loader would burn the operating system image to flash, the flash functions are required. As we know, there are there Erase functions, it make the boot loader can download and erase the image at same time, it can improve efficiency of system, but normally the writing is implemented after erasing. 5) Ether controller function 6) Timer function: The timer function is OEMEthGetSecs( ) function, This function returns the number of seconds that have passed since a specified fix。