cffi-lua

This is a portable C FFI for Lua, based on libffi. It aims to be
mostly compatible with the LuaJIT FFI, but written from scratch
and compatible with different systems and CPU architectures.

It doesn't aim to provide strictly only what LuaJIT FFI provides;
there is also support for features from newer Lua versions as well
as various other extensions, both in its API and in its language
support.