On Wed, 10 May 2023 at 13:25, Christophe Jorssen <christophe.jorssen@gmail.com> wrote:
Hi all,

If I'm not mistaken, there is no mention of FFI in the luatex reference manual (at least in 1.16).

Indeed, it's a very specialized subject, one needs to manage C and Lua quite well  --  and the code is not portable,  it's still  somewhat experimental (in lua) and it's quite easy to break luatex.
It's definitively for dedicated applications.
You can see https://luajit.org, the FFI sections.