where are source files and what are the ".a" files

[electronicsguy]

Hello,
    I am new to rockbox dev and compiling. I followed all the instructions in the first sticky thread on this forum and was able to compile the cross compiler and run make in the rockbox/build directory.

So my questions now are:
1) where are the source files for me to work with (I am using sansa E200R)
2) when i do the make in the rockbox/build directory, it creates a lot of lib*.a files. What are these files? Are these the final compiled files for the ARM firmware?
3) If I modify any source files (once I can find them!) what steps do I need to take to recompile them and create a final build?

Thanks

[MarcGuay]

Check out the developer's section in the documentation index.  The SimpleGuideToCompiling may be particularly useful.

[saratoga]

The source code is in the folder you downloaded or checked out of SVN.  Specifically, apps and firmware contain most of it.

[gnu]

*.c files are (usually) the source files.

[nls]

and the lib*.a files are various libraries that are linked together to become the final rockbox binary as well as codecs and plugins.