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diff --git a/c-user/red_black_trees.rst b/c-user/red_black_trees.rst new file mode 100644 index 0000000..77dcf3f --- /dev/null +++ b/c-user/red_black_trees.rst @@ -0,0 +1,119 @@ +.. comment SPDX-License-Identifier: CC-BY-SA-4.0 + +.. COMMENT: COPYRIGHT (c) 1988-2012. +.. COMMENT: On-Line Applications Research Corporation (OAR). +.. COMMENT: All rights reserved. + +Red-Black Trees +############### + +.. index:: rbtrees + +Introduction +============ + +The Red-Black Tree API is an interface to the SuperCore (score) rbtree +implementation. Within RTEMS, red-black trees are used when a binary search +tree is needed, including dynamic priority thread queues and non-contiguous +heap memory. The Red-Black Tree API provided by RTEMS is: + +- ``rtems_rtems_rbtree_node`` - Red-Black Tree node embedded in another struct + +- ``rtems_rtems_rbtree_control`` - Red-Black Tree control node for an entire tree + +- ``rtems_rtems_rbtree_initialize`` - initialize the red-black tree with nodes + +- ``rtems_rtems_rbtree_initialize_empty`` - initialize the red-black tree as empty + +- ``rtems_rtems_rbtree_set_off_tree`` - Clear a node's links + +- ``rtems_rtems_rbtree_root`` - Return the red-black tree's root node + +- ``rtems_rtems_rbtree_min`` - Return the red-black tree's minimum node + +- ``rtems_rtems_rbtree_max`` - Return the red-black tree's maximum node + +- ``rtems_rtems_rbtree_left`` - Return a node's left child node + +- ``rtems_rtems_rbtree_right`` - Return a node's right child node + +- ``rtems_rtems_rbtree_parent`` - Return a node's parent node + +- ``rtems_rtems_rbtree_are_nodes_equal`` - Are the node's equal ? + +- ``rtems_rtems_rbtree_is_empty`` - Is the red-black tree empty ? + +- ``rtems_rtems_rbtree_is_min`` - Is the Node the minimum in the red-black tree ? + +- ``rtems_rtems_rbtree_is_max`` - Is the Node the maximum in the red-black tree ? + +- ``rtems_rtems_rbtree_is_root`` - Is the Node the root of the red-black tree ? + +- ``rtems_rtems_rbtree_find`` - Find the node with a matching key in the red-black tree + +- ``rtems_rtems_rbtree_predecessor`` - Return the in-order predecessor of a node. + +- ``rtems_rtems_rbtree_successor`` - Return the in-order successor of a node. + +- ``rtems_rtems_rbtree_extract`` - Remove the node from the red-black tree + +- ``rtems_rtems_rbtree_get_min`` - Remove the minimum node from the red-black tree + +- ``rtems_rtems_rbtree_get_max`` - Remove the maximum node from the red-black tree + +- ``rtems_rtems_rbtree_peek_min`` - Returns the minimum node from the red-black tree + +- ``rtems_rtems_rbtree_peek_max`` - Returns the maximum node from the red-black tree + +- ``rtems_rtems_rbtree_insert`` - Add the node to the red-black tree + +Background +========== + +The Red-Black Trees API is a thin layer above the SuperCore Red-Black Trees +implementation. A Red-Black Tree is defined by a control node with pointers to +the root, minimum, and maximum nodes in the tree. Each node in the tree +consists of a parent pointer, two children pointers, and a color attribute. A +tree is parameterized as either unique, meaning identical keys are rejected, or +not, in which case duplicate keys are allowed. + +Users must provide a comparison functor that gets passed to functions that need +to compare nodes. In addition, no internal synchronization is offered within +the red-black tree implementation, thus users must ensure at most one thread +accesses a red-black tree instance at a time. + +Nodes +----- + +A red-black tree is made up from nodes that orginate from a red-black tree +control object. A node is of type ``rtems_rtems_rbtree_node``. The node is +designed to be part of a user data structure. To obtain the encapsulating +structure users can use the ``RTEMS_CONTAINER_OF`` macro. The node can be +placed anywhere within the user's structure and the macro will calculate the +structure's address from the node's address. + +Controls +-------- + +A red-black tree is rooted with a control object. Red-Black Tree control +provide the user with access to the nodes on the red-black tree. The +implementation does not require special checks for manipulating the root of the +red-black tree. To accomplish this the ``rtems_rtems_rbtree_control`` structure +is treated as a ``rtems_rtems_rbtree_node`` structure with a ``NULL`` parent +and left child pointing to the root. + +Operations +========== + +Examples for using the red-black trees can be found in the +``testsuites/sptests/sprbtree01/init.c`` file. + +Directives +========== + +Documentation for the Red-Black Tree Directives +----------------------------------------------- +.. index:: rbtree doc + +Source documentation for the Red-Black Tree API can be found in the generated +Doxygen output for ``cpukit/sapi``. |