Function CreateCipClass

source/src/cip/cipcommon.c:189–302

}

CipClass *CreateCipClass(const EipUint32 class_id,
                         const int number_of_class_attributes,
                         const EipUint32 highest_class_attribute_number,
                         const int number_of_class_services,
                         const int number_of_instance_attributes,
                         const EipUint32 highest_instance_attribute_number,
                         const int number_of_instance_services,
                         const int number_of_instances,
                         char *name,
                         const EipUint16 revision,
                         void (*InitializeCipClass)(CipClass *) ) {

  OPENER_TRACE_INFO("creating class '%s' with id: 0x%" PRIX32 "\n", name,
                    class_id);

  OPENER_ASSERT(NULL == GetCipClass(class_id) )     /* check if an class with the ClassID already exists */
  /* should never try to redefine a class*/

  /* a metaClass is a class that holds the class attributes and services
     CIP can talk to an instance, therefore an instance has a pointer to its class
     CIP can talk to a class, therefore a class struct is a subclass of the instance struct,
     and contains a pointer to a metaclass
     CIP never explicitly addresses a metaclass*/

  CipClass * const class = (CipClass *) CipCalloc(1, sizeof(CipClass) );       /* create the class object*/
  CipClass *const meta_class = (CipClass *) CipCalloc(1, sizeof(CipClass) );       /* create the metaclass object*/

  /* initialize the class-specific fields of the Class struct*/
  class->class_id = class_id;       /* the class remembers the class ID */
  class->revision = revision;       /* the class remembers the class ID */
  class->number_of_instances = 0;       /* the number of instances initially zero (more created below) */
  class->instances = 0;
  class->number_of_attributes = number_of_instance_attributes;       /* the class remembers the number of instances of that class */
  class->highest_attribute_number = highest_instance_attribute_number;       /* indicate which attributes are included in instance getAttributeAll */
  class->number_of_services = number_of_instance_services;       /* the class manages the behavior of the instances */
  class->services = 0;
  class->class_name = name;       /* initialize the class-specific fields of the metaClass struct */
  meta_class->class_id = 0xffffffff;       /* set metaclass ID (this should never be referenced) */
  meta_class->number_of_instances = 1;       /* the class object is the only instance of the metaclass */
  meta_class->instances = (CipInstance *) class;
  meta_class->number_of_attributes = number_of_class_attributes + 7;       /* the metaclass remembers how many class attributes exist*/
  meta_class->highest_attribute_number = highest_class_attribute_number;       /* indicate which attributes are included in class getAttributeAll*/
  meta_class->number_of_services = number_of_class_services;       /* the metaclass manages the behavior of the class itself */
  meta_class->class_name = (char *) CipCalloc(1, strlen(name) + 6);       /* fabricate the name "meta<classname>"*/
  snprintf(meta_class->class_name, strlen(name) + 6, "meta-%s", name);

  /* initialize the instance-specific fields of the Class struct*/
  class->class_instance.instance_number = 0;       /* the class object is instance zero of the class it describes (weird, but that's the spec)*/
  class->class_instance.attributes = 0;       /* this will later point to the class attibutes*/
  class->class_instance.cip_class = meta_class;       /* the class's class is the metaclass (like SmallTalk)*/
  class->class_instance.next = 0;       /* the next link will always be zero, sinc there is only one instance of any particular class object */

  meta_class->class_instance.instance_number = 0xffffffff;       /*the metaclass object does not really have a valid instance number*/
  meta_class->class_instance.attributes = 0;       /* the metaclass has no attributes*/
  meta_class->class_instance.cip_class = 0;       /* the metaclass has no class*/
  meta_class->class_instance.next = 0;       /* the next link will always be zero, since there is only one instance of any particular metaclass object*/

  /* further initialization of the class object*/