[practice] [Common Lisp] hello CFFI (Common Lisp + C)

README.md

This is a practice project to test Common Lisp + C with CFFI.

CFFI is a protocal for common lisp, and most popular impl like sbcl,ccl,cmucl,ecl and abcl have to this. So We can eazy to access C code from Common Lisp.

Env need

just only write for Linux(Unix) and need a lisp impl with cffi package. I pratice it with sbcl. You can install it with Roswell, or you can also ues more friendly env - cl-repl which also can install by roswell.

• OS: Linux(Unix)
• A Common lisp impl with cffi
• C compiler
  • gcc
• Make (or compile c file to library by self)

How to test

1. First compile C to a library(.so).
2. rum Common Lisp REPL
3. load lisp file

compile C to a library

just type make to gen libhello.so file

make

run Common Lisp REPL

sbcl

use sbcl, or ccl, ecl,ros run,cl-repl et.

load lisp file

(load "hello")

Output

direct call c function
56
Hello, World
Hello, Bob
Hello, Andy
---------------------------
define c function, then call
56
Hello, World
Hello, Bob
---------------------------
change var a to 100,
then sccess a:100

call showA:100

hello.c

#include<stdio.h>
#include<stdlib.h>

int a = 56;

void Hello(char *name){
  printf("Hello, %s\n", name);
}

/* int main(void){ */
/*   Hello("john"); */
/* } */


void HelloWorld(void){
  printf("Hello, World\n");
}


void ShowA(void){
  printf("%d\n", a);
}

hello.lisp

(require :cffi)
;;(use-package :cffi)

(defun write-hr nil
  (format t "~&---------------------------~&"))

;;; seting foreign library
(push '*default-pathname-defaults* cffi:*foreign-library-directories*)  ;; Add current directory to search Paths, or when use 'use-foreign-library will not Found.
(cffi:define-foreign-library libhello
  (:unix (:or "libhello.so.1" "libhello.so" "libhello.so.1.0.0")) ;; here can write as "./libhello.so" to select relative path file(current directory).
  (t (:default "libhello")))

(cffi:use-foreign-library libhello) ;; use forenign or use `(cffi:load-foreign-library "./libhello.so"), the later not need to define-foreign-library

(cffi:defcvar ("a" a) :int "A C var named a") ;; access C var which named a


;;; direct call c function
(format t "direct call c function~&")
(cffi:foreign-funcall "ShowA")
(cffi:foreign-funcall "HelloWorld")
(cffi:with-foreign-string (name "Bob")
  (cffi:foreign-funcall "Hello" :string name))
(cffi:foreign-funcall "Hello" :string "Andy")

(write-hr)
(format t "~&~&define c function, then call~&")
(cffi:defcfun ("ShowA" showA) :void )
(cffi:defcfun ("HelloWorld" hello-world) :void)
(cffi:defcfun ("Hello" hello) :void (name :string))
;; call c function
(showa)
(hello-world)
(hello "Bob")

(write-hr)
(format t "change var a to ~A,
then sccess a:~A~&
call showA:" (setf a 100) a)
(showA)

makefile

hello.so:
	gcc hello.c -shared -fPIC -Wl,-soname,libhello.so.1 -o libhello.so.1.0.0
	ln -rs libhello.so.1.0.0 libhello.so