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.