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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _AVL_IMPL_H
#define _AVL_IMPL_H
/*
* This is a private header file. Applications should not directly include
* this file.
*/
#include <sys/types.h>
#ifdef __cplusplus
extern "C" {
#endif
/*
* generic AVL tree implementation for kernel use
*
* There are 5 pieces of information stored for each node in an AVL tree
*
* pointer to less than child
* pointer to greater than child
* a pointer to the parent of this node
* an indication [0/1] of which child I am of my parent
* a "balance" (-1, 0, +1) indicating which child tree is taller
*
* Since they only need 3 bits, the last two fields are packed into the
* bottom bits of the parent pointer on 64 bit machines to save on space.
*/
#ifndef _LP64
struct avl_node {
struct avl_node *avl_child[2]; /* left/right children */
struct avl_node *avl_parent; /* this node's parent */
unsigned short avl_child_index; /* my index in parent's avl_child[] */
short avl_balance; /* balance value: -1, 0, +1 */
};
#define AVL_XPARENT(n) ((n)->avl_parent)
#define AVL_SETPARENT(n, p) ((n)->avl_parent = (p))
#define AVL_XCHILD(n) ((n)->avl_child_index)
#define AVL_SETCHILD(n, c) ((n)->avl_child_index = (unsigned short)(c))
#define AVL_XBALANCE(n) ((n)->avl_balance)
#define AVL_SETBALANCE(n, b) ((n)->avl_balance = (short)(b))
#else /* _LP64 */
/*
* for 64 bit machines, avl_pcb contains parent pointer, balance and child_index
* values packed in the following manner:
*
* |63 3| 2 |1 0 |
* |-------------------------------------|-----------------|-------------|
* | avl_parent hi order bits | avl_child_index | avl_balance |
* | | | + 1 |
* |-------------------------------------|-----------------|-------------|
*
*/
struct avl_node {
struct avl_node *avl_child[2]; /* left/right children nodes */
uintptr_t avl_pcb; /* parent, child_index, balance */
};
/*
* macros to extract/set fields in avl_pcb
*
* pointer to the parent of the current node is the high order bits
*/
#define AVL_XPARENT(n) ((struct avl_node *)((n)->avl_pcb & ~7))
#define AVL_SETPARENT(n, p) \
((n)->avl_pcb = (((n)->avl_pcb & 7) | (uintptr_t)(p)))
/*
* index of this node in its parent's avl_child[]: bit #2
*/
#define AVL_XCHILD(n) (((n)->avl_pcb >> 2) & 1)
#define AVL_SETCHILD(n, c) \
((n)->avl_pcb = (uintptr_t)(((n)->avl_pcb & ~4) | ((c) << 2)))
/*
* balance indication for a node, lowest 2 bits. A valid balance is
* -1, 0, or +1, and is encoded by adding 1 to the value to get the
* unsigned values of 0, 1, 2.
*/
#define AVL_XBALANCE(n) ((int)(((n)->avl_pcb & 3) - 1))
#define AVL_SETBALANCE(n, b) \
((n)->avl_pcb = (uintptr_t)((((n)->avl_pcb & ~3) | ((b) + 1))))
#endif /* _LP64 */
/*
* switch between a node and data pointer for a given tree
* the value of "o" is tree->avl_offset
*/
#define AVL_NODE2DATA(n, o) ((void *)((uintptr_t)(n) - (o)))
#define AVL_DATA2NODE(d, o) ((struct avl_node *)((uintptr_t)(d) + (o)))
/*
* macros used to create/access an avl_index_t
*/
#define AVL_INDEX2NODE(x) ((avl_node_t *)((x) & ~1))
#define AVL_INDEX2CHILD(x) ((x) & 1)
#define AVL_MKINDEX(n, c) ((avl_index_t)(n) | (c))
/*
* The tree structure. The fields avl_root, avl_compar, and avl_offset come
* first since they are needed for avl_find(). We want them to fit into
* a single 64 byte cache line to make avl_find() as fast as possible.
*/
struct avl_tree {
struct avl_node *avl_root; /* root node in tree */
int (*avl_compar)(const void *, const void *);
size_t avl_offset; /* offsetof(type, avl_link_t field) */
ulong_t avl_numnodes; /* number of nodes in the tree */
size_t avl_size; /* sizeof user type struct */
};
/*
* This will only by used via AVL_NEXT() or AVL_PREV()
*/
extern void *avl_walk(struct avl_tree *, void *, int);
#ifdef __cplusplus
}
#endif
#endif /* _AVL_IMPL_H */
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