Now, I build a project which have main.c source file, then I compile and link it. Then, I want to add the RSA.c to this project, and the new file will take much more memory, so can't I affect the already memory map and make the RSA.c use the RAM memory as there isn't the main.c, How can I do it ? Thanks very much.
You already have a thread on exctly this question - don't start it all over again here!
Go back to the original thread, read the comment about Overlaying, then look-up Overlaying in the Manual.
Then Try it.