+struct nitni_instance {
+ struct nitni_instance *next,
+ *prev; /* adjacent global references in global list */
+ int count; /* number of time this global reference has been marked */
+ struct instance *value;
+};
+
+/* Native reference to Nit objects */
+/* This structure is used to represent every Nit type in extern methods and custom C code. */
+struct nitni_ref {
+ struct nitni_ref *next,
+ *prev; /* adjacent global references in global list */
+ int count; /* number of time this global reference has been marked */
+};
+
+/* List of global references from C code to Nit objects */
+/* Instanciated empty at init of Nit system and filled explicitly by user in C code */
+struct nitni_global_ref_list_t {
+ struct nitni_ref *head, *tail;
+};
+extern struct nitni_global_ref_list_t *nitni_global_ref_list;
+
+/* Initializer of global reference list */
+extern void nitni_global_ref_list_init();
+
+/* Intern function to add a global reference to the list */
+extern void nitni_global_ref_add( struct nitni_ref *ref );
+
+/* Intern function to remove a global reference from the list */
+extern void nitni_global_ref_remove( struct nitni_ref *ref );
+
+/* Increase count on an existing global reference */
+extern void nitni_global_ref_incr( struct nitni_ref *ref );
+
+/* Decrease count on an existing global reference */
+extern void nitni_global_ref_decr( struct nitni_ref *ref );
+
+void show_backtrace(int) __attribute__ ((noreturn));
+#define likely(x) __builtin_expect((x),1)
+#define unlikely(x) __builtin_expect((x),0)