code: def do_init_cached_fields(self):
          
  
          cls_name = self.__class__
  
          # Build the fields information
          if Packet.class_default_fields.get(cls_name, None) is None:
              self.prepare_cached_fields(self.fields_desc)
  
          # Use fields information from cache
          if not Packet.class_default_fields.get(cls_name, None) is None:
              self.default_fields = Packet.class_default_fields[cls_name]
              self.fieldtype = Packet.class_fieldtype[cls_name]
              self.packetfields = Packet.class_packetfields[cls_name]
  
              # Deepcopy default references
              for fname in Packet.class_default_fields_ref[cls_name]:
                  value = copy.deepcopy(self.default_fields[fname])
                  setattr(self, fname, value)
docs: Initialize each fields of the fields_desc dict, or use the cached
          fields information