During the two last weeks, I began by healing. Now I'm in perfect health and I can do a better work.
I created a lot of unit tests. It was not an easy task because there is not a lot of comments on the code, and it can be difficult to understand what is the goal of each class/method. Also, my main language is not the C++ so I had some small issues with details.
Next week, I will implement Gcov. The goal is to know the test coverage of each part of the code. After that, I will create other unit tests.