Hello,

I am using Gambit4b12 to write a plugin for a C++ program.
I've done some tests and had some success although right now I'm having some problems when using it in a DLL.

First I would like to suggest a small improvement for the C code generation.
Maybe I'm missing a switch to pass to gsc but every time I generate the C code I have to add extern "C" {} wrapper around each file after I move all the #include outside that block. I also noticed that gambit.c doesn't have a extern "C" wrapper and I had to add it.

I think it would be simple to automatically add:
#ifdef __cplusplus extern "C" {} #endif wrapper when generating the code.
I don't know how easy would be to extract the includes in c-declare outside that wrapper but it would be nice to avoid manually editing the file.

The problem I'm having right now is that the code which runs fine in a single standalone program crashes when is called in a loaded DLL.

I think it must be something in the way the initialization has to be done but the documentation is not too clear.

If someone would be able to give me a hint I would appreciate it.
I am using mingw on Windows and I get this error:

Program received signal SIGSEGV, Segmentation fault.
0x1012a67f in ___CHARSTRING_to_UCS2STRING ()
   from c:\Gambitc_project\finalePlugin\testing\test.dll
(gdb) bt
#0  0x1012a67f in ___CHARSTRING_to_UCS2STRING ()
   from c:\Gambitc_project\finalePlugin\testing\test.dll
#1  0x00000000 in ?? () from
#2  0x0022fe68 in ?? ()
#3  0x101248b1 in ___alloc_mem ()
   from c:\Gambitc_project\finalePlugin\testing\test.dll
Previous frame inner to this frame (corrupt stack?)

The code is bellow.

Thank you,
Dan Hristodorescu.

- Main program:
#include <windows.h>
#include <stdio.h>
#include "note.h"

typedef void (*EntryPointfuncPtr)(EXNOTE*);
EntryPointfuncPtr callEntryPoint;
HINSTANCE library;

int main(int argc,char **argv)
{
        library = LoadLibrary("test.dll");     
        // Check to see if the library was loaded successfully
        if (library == 0)
        {
                printf("Couldn't load the DLL");
                exit(1);
        }      
    EXNOTE* note1 = new EXNOTE();
    note1->tcd=1;
    note1->alteration=1;
    note1->noteID=1;
    note1->flag=1;
    printf("Address=0x%X\n", note1);
       
        callEntryPoint = (EntryPointfuncPtr)GetProcAddress(library,"_Z10entryPointP6EXNOTE");
        (*callEntryPoint)(note1);
        printf("Note->tcd= %d\n", note1->tcd);
    printf("Note->alteration= %d\n", note1->alteration);
    printf("Note->noteID= %d\n", note1->noteID);
    printf("Note->flag= %d\n", note1->flag);
    delete note1;      
}

DLL code:
#include <windows.h>
#include <stdio.h>
#include "note.h"

extern "C" void pluginEntry(EXNOTE*);

#define ___VERSION 40062
#include "gambit.h"

#define SCHEME_LIBRARY_LINKER ____20_testscm__

___BEGIN_C_LINKAGE
extern ___mod_or_lnk SCHEME_LIBRARY_LINKER (___global_state_struct*);
___END_C_LINKAGE

CALLBACK void  entryPoint(EXNOTE* note1)
{
  ___setup_params_struct setup_params;
  ___setup_params_reset (&setup_params);
  setup_params.version = ___VERSION;
  setup_params.linker  = SCHEME_LIBRARY_LINKER;
  ___setup (&setup_params);            

  pluginEntry(note1);

   ___cleanup ();
}

note.h file:
#ifndef _NOTE_H_
#define _NOTE_H_

typedef short twobyte;
typedef unsigned long ufourbyte;
typedef ufourbyte FLAG_32;

class EXNOTE
{
public:
        twobyte tcd;
        twobyte alteration;
        twobyte noteID;
        FLAG_32 flag;

        EXNOTE() : tcd(0), alteration(0), noteID(0), flag(0) {}
        ~EXNOTE() {}
};
#endif

Scheme code:

(c-declare "
#include \"note.h\"
")

(c-define-type twobyte short)
(c-define-type ufourbyte unsigned-long)
(c-define-type FLAG_32 ufourbyte)

;;
;;;;   EXNOTE
;;;

(c-define-type EXNOTE* (pointer "EXNOTE"))

(define EXNOTE-tcd
  (c-lambda (EXNOTE*)
            twobyte
            "___result = ___arg1->tcd;"))

(define EXNOTE-tcd-set!
  (c-lambda (EXNOTE* twobyte)
            void
            "___arg1->tcd = ___arg2;"))

(define transpose-note
  (lambda (note step)
    (EXNOTE-tcd-set! note (+ (EXNOTE-tcd note) step))))
               
(c-define (pluginEntry x) (EXNOTE*) void "pluginEntry" "extern"
      (write x)
      (newline)
      (transpose-note x 3))