It supports structures by-value and by-reference with and without saving C-pointer on lisp side. Also there is type object, that allows to send lisp object with pointer slot or C-pointer. No documentation yet. Look into sources of GTK-CFFI for usage examples.
Depends on: CFFI, trivial-garbage, closer-mop
Repository: https://common-lisp.net/viewvc/cffi-objects/
BSD license FFI