7.3 Using the Foreign Parser

The interface is the function foreign-parser:process-foreign-file.

The following example uses this C source code in file test.c . It needs to be slightly different depending on your platform.

Windows version:

#include <stdio.h>

#include <string.h>

__declspec(dllexport) void __cdecl modify(char *string)

{

  char temp[256];

  sprintf(temp, "'%s' modified in a C function", string);

  strcpy(string, temp);

}

Linux/Unix version:

#include <stdio.h>

#include <string.h>

void modify(char *string)

{

  char temp[256];

  sprintf(temp, "'%s' modified in a C function", string);

  strcpy(string, temp);

}

1. Load the Foreign Parser:
(require "foreign-parser")
2. Now generate prototype FLI definitions:

(foreign-parser:process-foreign-file

 "test.c"

 :case-sensitive nil)

=>

;;;    Output dff file #P"test-dff.lisp"

;;;    Parsing source file "test.c"

;;; Process-foreign-file : Preprocessing file

;;; Process-foreign-file : Level 1 parsing

;;; Process-foreign-file : Selecting foreign forms

NIL

3. You should now have a Lisp file test-dff.lisp containing a form like this:

(fli:define-foreign-function

    (modify "modify" :source)

    ((string (:pointer :char)))

  :result-type

  :void

  :language

  :c

  :calling-convention

  :cdecl)

4. This edited version passes a string using :ef-mb-string :

(fli:define-foreign-function

    (modify "modify" :source)

    ((string (:reference (:ef-mb-string :limit 256))))

  :result-type

  :void

  :language

  :c

  :calling-convention

  :cdecl)

=>

MODIFY

5. Load the foreign code by
(fli:register-module "test.dll")

or

(fli:register-module "/tmp/test.so")
6. Call the C function from LISP:

(modify "Hello, I am in LISP")

=>

NIL

"'Hello, I am in LISP' modified in a C function"