vcan_linkdata
=============

Here is the definition::

  typedef struct
    { long port1   CDEP_NOALIGN_ATTR;
      long id1     CDEP_NOALIGN_ATTR;
      long port2   CDEP_NOALIGN_ATTR;
      long id2     CDEP_NOALIGN_ATTR;
    } vcan_linkdata;

This is the driver-call-sub-structure that is used when 2 objects, usually
of different ports, have to be linked. It is used in conjunction with the
``VCAN_LINK`` and the ``VCAN_UNLINK`` sub-function. When two objects are
linked, data arriving on one object on one port is transferred to another
object on the second port. Note that the two ports must be the ports of a
single VME-CAN2 or VME-CAN4 card.

port1
  This is the number of the first port. Both ports must be on the same card,
  so ``port1 DIV 2`` must equal ``port2 DIV 2``, ``DIV`` meaning an
  integer-division of numbers.

id1
  This is the id of the first object that is to be linked.

port2
  This is the number of the second port. Both ports must be on the same
  card, so ``port1 DIV 2`` must equal ``port2 DIV 2``, ``DIV`` meaning an
  integer-division of numbers.

id2
  This is the id of the second object that is to be linked.