The "Muditulib" library is introduced and explained. Muditulib is mainly a library consisting of a collection of C header files that include functions written for the purpose of tuning tonal music within the diatonic scale. This scale, as well as the library's functions, along with pitch representation systems, will be explained in detail or just shortly with reference to other literature. A music theoretical background is useful, though not necessary. Along with the core of header files an implementation for Pure Data is published. Developers are encouraged to write implementations for other synthesizers, music production platforms or any other link in the chain of tonal music production workflow.