A Program Loading Method Research And Application During Mobile Phones Softwares' Development

In present day feature phones are use static linking, they can compile all the application programs and the kernel into binary files which can be run on a target machine and then download these files to nonvolatile memorizer to run. In this method, the only thing to do is to add the native application programs if you want to perfect the feature phones'features. But it cannot load the third application programs. However, the hardware resources of feature phones system are limit, the increasing native application programs are conflict with the nonvolatile memorizer. So most feature telephones are basically implement the third application programs through middlewares, such as through transplanting J2ME. But the transplantation will add the substantial amount of system overhead; it will take about 1.2MB ROM loading space and about 600KB RAM space at runtime. This method has not a perfect effect.This paper put forward and realized a new method of dynamic loading which based on a project (to implement the dynamic loading of third application programs on feature phones with lower system overhead ) through the research of the embeded system programs'static loading method, the implementation method of functions'jumping table, the feature phones'dynamic loading method of the third application programs and the ELF files'dynamic loading method. Its main ideal is: first, compiling the programs through ADS1.2 on the side of PCs to specify the virtual ROM address and RAM address to form ELF files. In these files contain the addresses (virtual addresses) of all data which need to be reloaded. Then, transforming each segment of ELF file according to its own file format to form a new file. During dynamic loading, the RAM of feature phones requires the same size space of the file, and then the entire file loaded into RAM. Through reloading of the data, the data's location will be found. The data address minus the virtual RAM address, and adds the first address of the space which applied on the target side. Thus, this completed the reloading. Then let the PC pointer of the feature phones point to the code's first address, and directly run to complete the dynamic loading.According to dynamic loading method proposed by this paper, it successfully designed and implemented a dynamic loading platform of application programs which is developed by the third party's in MTK feature phone development environment, and extends the program's loading function of feature phones. After the test, the dynamic loading platform occupies very few system resources. During loading, it needed the target side 31KB ROM space and less than 1KB RAM space at non-runtime and successfully loaded 2450 third party developers'application programs which meet the MTK programming standards in the 1GB card and occupied less than 600MB space in t card. It runs smoothly, its speed is good, and it gives a very good solution to the issue raised by the application and manufacturers.