The libffi library provides a portable, high level programming
interface to various calling conventions. This allows a programmer
to call any function specified by a call interface description at
run-time.

FFI stands for Foreign Function Interface. A foreign function
interface is the popular name for the interface that allows code
written in one language to call code written in another language.
The libffi library really only provides the lowest, machine
dependent layer of a fully featured foreign function interface. A
layer must exist above libffi that handles type conversions for
values passed between the two languages.