Steel Bank Common Lisp

Hi SBCL helpers.

I think I may have tripped upon a possible problem with how SBCL deals with certain procedure parameters for foreign functions called with the stdcall calling convention in WIN32.  It appears that c-strings (or char *'s) may not be passed correctly  (or I am doing something wrong).  Here is an example with C++  code and lisp.  Note that I build a DLL using the C++ compiler, but this is just simple C code.  I have built this dll with both MSVC and Eclipse (with some gcc-specific changes) on Windows.

*********** The C++ code ************************
typedef struct  simple_s
{
    int (__stdcall* simple)( int in_1);
    char (__stdcall  * simple_1)( char * in_string, int * strlen );
    char (__stdcall  * simple_2)( char * in_string );
} simple_struct;


int  __stdcall  simple( int in_1)
{
    return in_1 + 10;
}

__declspec(dllexport) char  __stdcall simple_1( char * in_string , int * the_strlen)
{
    char c;
    printf( "Hello\n" );
    c = in_string[0];
    *the_strlen = strlen( in_string );
    return c;
    //return 'A';
}


/// this one does not work!! 
__declspec(dllexport) char  __stdcall simple_2( char * in_string )
{
    char c;
    printf( "Hello\n" );
    c = in_string[0];
    return c;
}

__declspec(dllexport) simple_struct s =
{
        &simple,
        &simple_1,
        &simple_2
};


__declspec(dllexport) int  __stdcall GetSimpleStruct( simple_struct ** the_out_struct_ptr )
{
    *the_out_struct_ptr = &s;
    return 0;
}


**************** The Lisp Interaction *************************
(sb-alien:load-shared-object 
      "C:/Documents and Settings/John Whittaker/My Documents/Visual Studio 2005/Projects/simple_dll/debug/simple_dll.dll")
#P"C:\\Documents and Settings\\John Whittaker\\My Documents\\Visual Studio 2005\\Projects\\simple_dll\\debug\\simple_dll.dll"
CL-USER> (sb-alien:define-alien-type simple-struct 
         (sb-alien:struct simple-struct
                  (simple (* (sb-alien:function int int)))
                  (simple_1(* (sb-alien:function char (* char ) (* int))))
                  (simple_2 (* (sb-alien:function char (* char))))))
SIMPLE-STRUCT
CL-USER> (setf me-len (make-alien int))

; in: LAMBDA NIL
;     SETF
; ==>
;   (SETQ ME-LEN (MAKE-ALIEN INT))
; 
; caught WARNING:
;   undefined variable: ME-LEN

; 
; caught WARNING:
;   This variable is undefined:
;     ME-LEN
; 
; compilation unit finished
;   caught 2 WARNING conditions
#<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #X003D71A8 :TYPE (* (SIGNED 32))>
#<SB-ALIEN-INTERNALS:ALIEN-VALUE :SAP #X003D71A8 :TYPE (* (SIGNED 32))>

CL-USER> (sb-alien:define-alien-routine  ("simple_2" simple-2 )
  char
  (the-in-string  (* char)))
STYLE-WARNING: redefining SIMPLE-2 in DEFUN
SIMPLE-2
CL-USER> 
; No value
CL-USER> 
; No value
CL-USER> (sb-alien:define-alien-routine  ("simple_1" simple-1 )
  char
  (the-in-string  c-string) (the-out-strlen (* int)))
STYLE-WARNING: redefining SIMPLE-1 in DEFUN
SIMPLE-1
CL-USER> (simple-1 "hello there" (addr (deref me-len)))
104
CL-USER> (char-int #\h)
104
CL-USER> (deref me-len)
11
CL-USER> (sb-alien:define-alien-routine  ("simple_2" simple-2 )
  char
  (the-in-string  c-string))
STYLE-WARNING: redefining SIMPLE-2 in DEFUN
SIMPLE-2
CL-USER> (simple-2 "hello")
182057064   <<<<<----------- What is this?????????????????
CL-USER> 


Is there something I am doing wrong in the interface definition for the single parameter function?    I seem to get the same results whether I call the functions directly or through the function table.  (I'm trying to ultimately get JFLI working with SBCL and the JNI interface is a large function table).

Thanks for any help you could provide!!

BTW: I love the foreign function interface of SBCL.  I have tried to do the same JFLI work with clisp and have thrown it over for SBCL now that I see SBCL runs (pretty well) on Windows.  The SBCL FFI is SOOOOO MUCH easier to understand even though it could be further documented.

John Whittaker