yurivict / cffi

The Common Foreign Function Interface

What

CFFI, the Common Foreign Function Interface, purports to be a portable FFI for Common Lisp. It abstracts away the differences between the API of the native FFI's of the various Common Lisp implementations.

How

The CFFI library is composed of a Lisp-implementation-specific backend in the CFFI-SYS package, and a portable frontend in the CFFI package.

The CFFI-SYS backend package defines a low-level interface to the native FFI support in the Lisp implementation. It offers operators for allocating and dereferencing foreign memory, calling foreign functions, and loading shared libraries.

The CFFI frontend provides a more comfortable, declarative interface for defining foreign functions, structures, typedefs, enumerated types, etc. It is implemented in portable ANSI CL making use of the low-level operators exported by CFFI-SYS.

The CFFI-LIBFFI subsystem loads support for passing structs by value. It requires libffi for that.

Please consult the manual for further details, including installation instructions.

Where

Please visit Github for bug reports, feature suggestions, the latest version, and to send your contributions. CFFI also has a mailing list, and a project page at cffi.common-lisp.dev.

Notes

CFFI/C2FFI

CFFI/C2FFI is an ASDF-integrated mechanism to automatically generate a complete CFFI binding from a C header file. It requires a CLI tool called c2ffi, but only for the developers of the libraries, not their users. c2ffi is written in C++, and it uses LLVM/Clang as the parsing library. It generates JSON output that can be checked in into the repositories. CFFI/C2FFI uses these JSON files to automatically generate a CL file that contains the CFFI definition forms. The generated bindings mirror the C namespace into an otherwise empty CL package as closely as possible. It means that they retain the upper/lower case of the names, and it also includes the #define macros as CL constants.

Until CFFI/C2FFI is properly documented, you may check out these projects as examples: hu.dwim.zlib, hu.dwim.sdl, hu.dwim.bluez, and hu.dwim.mosquitto.

Related projects

• cl-autowrap is another project that uses c2ffi to generate CFFI bindings.