libdragon provides a low level API for all hardware features of the N64. Currently, it provides basic console support, rudimentary higher level controller functions, a read only filesystem for appending data to the end of a rom, audio support and some 2D graphics functionality. It also includes bindings to newlib in order to provide a posix interface to filesystems.
libdragon is currently made up of three core components: the libdragon library, newlib Interface Hooks and DragonFS. The core library provides drivers for each hardware component in the N64 and low level API for interacting with the components. The system hooks provide a translation layer between libdragon and newlib for the purpose of POSIX compatibility. DragonFS provides the read only filesystem support and is hooked into newlib using the system hooks.
Please see the documentation in individual modules for additional information.