rem: ClearSemaphore (&_MemorySem);
add: ClearSemaphore (_MemorySem);
context: mem_simple_access(MEM_HANDLE h){	SetSemaphore (&_MemorySem);	if (h > 0 && h <= MAX_EXTENTS && extents[h - 1].handle == h)	{		++extents[h - 1].refcount;		ClearSemaphore (&_MemorySem);		return (extents[h - 1].memory);	}	ClearSemaphore (&_MemorySem);	return (0);}