#define SGEN_TV_GETTIME(tv) tv = mono_100ns_ticks ()
#define SGEN_TV_ELAPSED(start,end) ((gint64)(end-start))
+guint64 mono_time_since_last_stw (void);
+
typedef MonoSemType SgenSemaphore;
#define SGEN_SEMAPHORE_INIT(sem,initial) mono_os_sem_init ((sem), (initial))