I started a while ago to learn the C language, and has spent several hours I search THE miracle software.
I am looking for software that import sources of software in C (files.c) and generates a "mind map" of the code with all files, functions, variables, etc ...
Do you know if it exists? It'll help me a lot to understand the architecture of complex software.
Thank you very much for all your answers.
Take a look at the "call graph". This sort of visualization should get you started.
As the comment suggests, Doxygen is a good open-source tool. Take a look at some output here. Doxygen is straight-forward to configure for call-graph generation under *nix. It's a little more complex for Windows. First, check out this SO post: how to get doxygen to produce call & caller graphs for c functions. Doxygen's HTML output provides a number of nice cross-referencing features (files, variables, structs, etc.) in addition to caller/callee graphs.
On the commercial side, Understand for C/C++ has first-rate visualization features. Google "c call graph diagram" for other commercial and open-source options.
Finally, there are some older SO posts, like this one Tools to get a pictorial function call graph of code. Take a look at it.