RTEMS 4.9.2 On-Line Library

Chains Controls

RTEMS Ada User's Guide

28.2.2: Controls

A chain is anchored with a control object. Chain control provide the user with access to the nodes on the chain. The control is head of the node.

       Control
        next ------------------------->
        permanent_null <--------------- NODE
        last ------------------------->

The implementation does not require special checks for manipulating the first and last nodes on the chain. To accomplish this the rtems.chain_control structure is treated as two overlapping rtems.chain_node structures. The permanent head of the chain overlays a node structure on the first and permanent_null fields. The permanent_tail of the chain overlays a node structure on the permanent_null and last elements of the structure.

RTEMS Ada User's Guide