I want to ask about a movie i have seen awhile back?

awhile back i had seen a movie about a mixed boy who moves out of his parents home to live on the streets and become a better writer/rapper. through the story he seems to dream maybe from being homeless.. to a police officer... to a famous rapper.. and throughout the movie who undergoes changes with 2 friends i think one was a crackhead.... does anybody know the name of this movie... im sorry for being vague but i dont know what details are important