/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * This file is part of SableVM.                             *
 * See the file "LICENSE" for Copyright information and the  *
 * terms and conditions for copying, distribution and        *
 * modification of SableVM.                                  *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

/*
----------------------------------------------------------------------
_svmh_new_native_local
----------------------------------------------------------------------
*/

static jint
_svmh_new_native_local (_svmt_JNIEnv *env, jobject *pobj)
{
  _svmt_JavaVM *vm = env->vm;
  _svmt_native_ref *native_local = NULL;

  /* do we already have a free reference available? */
  if (env->native_locals.free_list != NULL)
    {
      native_local = env->native_locals.free_list;

      env->native_locals.free_list = native_local->next;
      if (env->native_locals.free_list != NULL)
	{
	  assert (env->native_locals.free_list->previous == native_local);

	  env->native_locals.free_list->previous = NULL;
	}

      assert (native_local->previous == NULL);

      native_local->next = env->native_locals.list;
      env->native_locals.list = native_local;
      if (native_local->next != NULL)
	{
	  assert (native_local->next->previous == NULL);

	  native_local->next->previous = native_local;
	}

      *pobj = _svmf_cast_jobject_nref (native_local);
      return JNI_OK;
    }

  /* Can we steal a free global native reference? */
  _svmm_mutex_lock (vm->global_mutex);

  if (vm->native_globals.free_list != NULL)
    {
      native_local = vm->native_globals.free_list;

      vm->native_globals.free_list = native_local->next;
      if (vm->native_globals.free_list != NULL)
	{
	  assert (vm->native_globals.free_list->previous == native_local);

	  vm->native_globals.free_list->previous = NULL;
	}
    }

  _svmm_mutex_unlock ();

  if (native_local != NULL)
    {
      assert (native_local->previous == NULL);

      native_local->next = env->native_locals.list;
      env->native_locals.list = native_local;
      if (native_local->next != NULL)
	{
	  assert (native_local->next->previous == NULL);

	  native_local->next->previous = native_local;
	}

      *pobj = _svmf_cast_jobject_nref (native_local);
      return JNI_OK;
    }

  /* we're out of luck; let's allocate a new reference */
  if (_svmm_gzalloc_native_ref_no_exception (native_local) != JNI_OK)
    {
      _svmf_error_OutOfMemoryError (env);
      return JNI_ERR;
    }

  native_local->next = env->native_locals.list;
  env->native_locals.list = native_local;

  if (native_local->next != NULL)
    {
      assert (native_local->next->previous == NULL);

      native_local->next->previous = native_local;
    }

  *pobj = _svmf_cast_jobject_nref (native_local);
  return JNI_OK;
}

/*
----------------------------------------------------------------------
_svmh_free_native_local
----------------------------------------------------------------------
*/

static void
_svmh_free_native_local (_svmt_JNIEnv *env, jobject *pobj)
{
  _svmt_native_ref *native_local = _svmf_cast_nref_jobject (*pobj);

  if (native_local->next != NULL)
    {
      native_local->next->previous = native_local->previous;
    }

  if (native_local->previous != NULL)
    {
      native_local->previous->next = native_local->next;
    }
  else
    {
      env->native_locals.list = native_local->next;
    }

  native_local->ref = NULL;
  native_local->previous = NULL;
  native_local->next = env->native_locals.free_list;

  env->native_locals.free_list = native_local;

  if (native_local->next != NULL)
    {
      assert (native_local->next->previous == NULL);

      native_local->next->previous = native_local;
    }

  *pobj = NULL;
}

/*
----------------------------------------------------------------------
_svmf_get_jni_frame_native_local
----------------------------------------------------------------------
*/

/* NOTE: IT IS IMPORTANT to assign a value OTHER THAN NULL into the
 * returned jobject BEFORE calling this method again. IF YOU DON'T
 * follow rigorously this rule, you will probably experience problems,
 * as this function will repeatedly return the exact same jobject.
 *
 * This function is provided as a convenient way to avoid checking
 * return values (as would be necessary with _svmf_new_native_local),
 * by using stack frame reserved JNI jobjects.  Its primary function
 * is to help implement the JNI mechanism.  So, if you're not sure,
 * simply use _svmf_new_native_local; you'll then be safe.
 */

static jobject
_svmf_get_jni_frame_native_local (_svmt_JNIEnv *env)
{
  _svmt_JavaVM *vm = env->vm;
  _svmt_stack_frame *frame = env->stack.current_frame;
  _svmt_method_info *method = frame->method;
  _svmt_stack_native_reference *lrefs = (_svmt_stack_native_reference *)
    (((char *) frame) + frame->end_offset);
  jint lrefs_count = lrefs[-1].jint;
  size_t lrefs_size = lrefs[-2].size_t;
  jint i;

  assert (method == &vm->stack_bottom_method
	  || _svmf_is_set_flag (method->access_flags, SVM_ACC_NATIVE));

  lrefs = (_svmt_stack_native_reference *) (((char *) lrefs) - lrefs_size);

  for (i = 0; i < lrefs_count; i++)
    {
      if (*(lrefs[i].jobject) == NULL)
	{
	  return lrefs[i].jobject;
	}
    }

  _svmf_jni_fatal_error ("Local reference capacity exceeded");
  return NULL;			/* to keep compiler happy. */
}

/*
----------------------------------------------------------------------
_svmm_release_jni_frame_native_local
----------------------------------------------------------------------
*/

#define _svmm_release_jni_frame_native_local(obj) \
_svmh_release_jni_frame_native_local (&obj)

static void
_svmh_release_jni_frame_native_local (jobject *pobj)
{
  **pobj = NULL;
  *pobj = NULL;
}

/*
----------------------------------------------------------------------
_svmf_get_jni_frame_native_local_array
----------------------------------------------------------------------
*/

/* NOTE: IT IS IMPORTANT to assign a value OTHER THAN NULL into the
 * returned jarray BEFORE calling this method again. IF YOU DON'T
 * follow rigorously this rule, you will probably experience problems,
 * as this function will repeatedly return the exact same jarray.
 *
 * This function is provided as a convenient way to avoid checking
 * return values (as would be necessary with
 * _svmf_new_native_local_array), by using stack frame reserved JNI
 * jobjects.  Its primary function is to help implement the JNI
 * mechanism.  So, if you're not sure, simply use
 * _svmf_new_native_local_array; you'll then be safe.
 */

static jarray
_svmf_get_jni_frame_native_local_array (_svmt_JNIEnv *env)
{
  return _svmf_cast_jarray (_svmf_get_jni_frame_native_local (env));
}

/*
----------------------------------------------------------------------
_svmm_release_jni_frame_native_local_array
----------------------------------------------------------------------
*/

#define _svmm_release_jni_frame_native_local_array(array) \
_svmh_release_jni_frame_native_local_array (&array)

static void
_svmh_release_jni_frame_native_local_array (jarray *parray)
{
  **parray = NULL;
  *parray = NULL;
}