1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#ifndef _AVL_IMPL_H
28#define _AVL_IMPL_H
29
30#pragma ident "%Z%%M% %I% %E% SMI"
31
32/*
33 * This is a private header file. Applications should not directly include
34 * this file.
35 */
36
37#include <sys/types.h>
38
39#ifdef __cplusplus
40extern "C" {
41#endif
42
43
44/*
45 * generic AVL tree implementation for kernel use
46 *
47 * There are 5 pieces of information stored for each node in an AVL tree
48 *
49 * pointer to less than child
50 * pointer to greater than child
51 * a pointer to the parent of this node
52 * an indication [0/1] of which child I am of my parent
53 * a "balance" (-1, 0, +1) indicating which child tree is taller
54 *
55 * Since they only need 3 bits, the last two fields are packed into the
56 * bottom bits of the parent pointer on 64 bit machines to save on space.
57 */
58
59#ifndef _LP64
60
61struct avl_node {
62 struct avl_node *avl_child[2]; /* left/right children */
63 struct avl_node *avl_parent; /* this node's parent */
64 unsigned short avl_child_index; /* my index in parent's avl_child[] */
65 short avl_balance; /* balance value: -1, 0, +1 */
66};
67
68#define AVL_XPARENT(n) ((n)->avl_parent)
69#define AVL_SETPARENT(n, p) ((n)->avl_parent = (p))
70
71#define AVL_XCHILD(n) ((n)->avl_child_index)
72#define AVL_SETCHILD(n, c) ((n)->avl_child_index = (unsigned short)(c))
73
74#define AVL_XBALANCE(n) ((n)->avl_balance)
75#define AVL_SETBALANCE(n, b) ((n)->avl_balance = (short)(b))
76
77#else /* _LP64 */
78
79/*
80 * for 64 bit machines, avl_pcb contains parent pointer, balance and child_index
81 * values packed in the following manner:
82 *
83 * |63 3| 2 |1 0 |
84 * |-------------------------------------|-----------------|-------------|
85 * | avl_parent hi order bits | avl_child_index | avl_balance |
86 * | | | + 1 |
87 * |-------------------------------------|-----------------|-------------|
88 *
89 */
90struct avl_node {
91 struct avl_node *avl_child[2]; /* left/right children nodes */
92 uintptr_t avl_pcb; /* parent, child_index, balance */
93};
94
95/*
96 * macros to extract/set fields in avl_pcb
97 *
98 * pointer to the parent of the current node is the high order bits
99 */
100#define AVL_XPARENT(n) ((struct avl_node *)((n)->avl_pcb & ~7))
101#define AVL_SETPARENT(n, p) \
102 ((n)->avl_pcb = (((n)->avl_pcb & 7) | (uintptr_t)(p)))
103
104/*
105 * index of this node in its parent's avl_child[]: bit #2
106 */
107#define AVL_XCHILD(n) (((n)->avl_pcb >> 2) & 1)
108#define AVL_SETCHILD(n, c) \
109 ((n)->avl_pcb = (uintptr_t)(((n)->avl_pcb & ~4) | ((c) << 2)))
110
111/*
112 * balance indication for a node, lowest 2 bits. A valid balance is
113 * -1, 0, or +1, and is encoded by adding 1 to the value to get the
114 * unsigned values of 0, 1, 2.
115 */
116#define AVL_XBALANCE(n) ((int)(((n)->avl_pcb & 3) - 1))
117#define AVL_SETBALANCE(n, b) \
118 ((n)->avl_pcb = (uintptr_t)((((n)->avl_pcb & ~3) | ((b) + 1))))
119
120#endif /* _LP64 */
121
122
123
124/*
125 * switch between a node and data pointer for a given tree
126 * the value of "o" is tree->avl_offset
127 */
128#define AVL_NODE2DATA(n, o) ((void *)((uintptr_t)(n) - (o)))
129#define AVL_DATA2NODE(d, o) ((struct avl_node *)((uintptr_t)(d) + (o)))
130
131
132
133/*
134 * macros used to create/access an avl_index_t
135 */
136#define AVL_INDEX2NODE(x) ((avl_node_t *)((x) & ~1))
137#define AVL_INDEX2CHILD(x) ((x) & 1)
138#define AVL_MKINDEX(n, c) ((avl_index_t)(n) | (c))
139
140
141/*
142 * The tree structure. The fields avl_root, avl_compar, and avl_offset come
143 * first since they are needed for avl_find(). We want them to fit into
144 * a single 64 byte cache line to make avl_find() as fast as possible.
145 */
146struct avl_tree {
147 struct avl_node *avl_root; /* root node in tree */
148 int (*avl_compar)(const void *, const void *);
149 size_t avl_offset; /* offsetof(type, avl_link_t field) */
150 ulong_t avl_numnodes; /* number of nodes in the tree */
151 size_t avl_size; /* sizeof user type struct */
152};
153
154
155/*
156 * This will only by used via AVL_NEXT() or AVL_PREV()
157 */
158extern void *avl_walk(struct avl_tree *, void *, int);
159
160#ifdef __cplusplus
161}
162#endif
163
164#endif /* _AVL_IMPL_H */
165