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 https://opensource.org/licenses/CDDL-1.0.
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 extern __attribute__((visibility("default")))
29 
30 
31 /*
32  * This is a private header file.  Applications should not directly include
33  * this file.
34  */
35 
36 #include <sys/types.h>
37 
38 #ifdef	__cplusplus
39 extern "C" {
40 #endif
41 
42 
43 /*
44  * generic AVL tree implementation for kernel use
45  *
46  * There are 5 pieces of information stored for each node in an AVL tree
47  *
48  * 	pointer to less than child
49  * 	pointer to greater than child
50  * 	a pointer to the parent of this node
51  *	an indication  [0/1]  of which child I am of my parent
52  * 	a "balance" (-1, 0, +1)  indicating which child tree is taller
53  *
54  * Since they only need 3 bits, the last two fields are packed into the
55  * bottom bits of the parent pointer on 64 bit machines to save on space.
56  */
57 
58 #ifndef _LP64
59 
60 struct avl_node {
61 	struct avl_node *avl_child[2];	/* left/right children */
62 	struct avl_node *avl_parent;	/* this node's parent */
63 	unsigned short avl_child_index;	/* my index in parent's avl_child[] */
64 	short avl_balance;		/* balance value: -1, 0, +1 */
65 };
66 
67 #define	AVL_XPARENT(n)		((n)->avl_parent)
68 #define	AVL_SETPARENT(n, p)	((n)->avl_parent = (p))
69 
70 #define	AVL_XCHILD(n)		((n)->avl_child_index)
71 #define	AVL_SETCHILD(n, c)	((n)->avl_child_index = (unsigned short)(c))
72 
73 #define	AVL_XBALANCE(n)		((n)->avl_balance)
74 #define	AVL_SETBALANCE(n, b)	((n)->avl_balance = (short)(b))
75 
76 #else /* _LP64 */
77 
78 /*
79  * for 64 bit machines, avl_pcb contains parent pointer, balance and child_index
80  * values packed in the following manner:
81  *
82  * |63                                  3|        2        |1          0 |
83  * |-------------------------------------|-----------------|-------------|
84  * |      avl_parent hi order bits       | avl_child_index | avl_balance |
85  * |                                     |                 |     + 1     |
86  * |-------------------------------------|-----------------|-------------|
87  *
88  */
89 struct avl_node {
90 	struct avl_node *avl_child[2];	/* left/right children nodes */
91 	uintptr_t avl_pcb;		/* parent, child_index, balance */
92 };
93 
94 /*
95  * macros to extract/set fields in avl_pcb
96  *
97  * pointer to the parent of the current node is the high order bits
98  */
99 #define	AVL_XPARENT(n)		((struct avl_node *)((n)->avl_pcb & ~7))
100 #define	AVL_SETPARENT(n, p)						\
101 	((n)->avl_pcb = (((n)->avl_pcb & 7) | (uintptr_t)(p)))
102 
103 /*
104  * index of this node in its parent's avl_child[]: bit #2
105  */
106 #define	AVL_XCHILD(n)		(((n)->avl_pcb >> 2) & 1)
107 #define	AVL_SETCHILD(n, c)						\
108 	((n)->avl_pcb = (uintptr_t)(((n)->avl_pcb & ~4) | ((c) << 2)))
109 
110 /*
111  * balance indication for a node, lowest 2 bits. A valid balance is
112  * -1, 0, or +1, and is encoded by adding 1 to the value to get the
113  * unsigned values of 0, 1, 2.
114  */
115 #define	AVL_XBALANCE(n)		((int)(((n)->avl_pcb & 3) - 1))
116 #define	AVL_SETBALANCE(n, b)						\
117 	((n)->avl_pcb = (uintptr_t)((((n)->avl_pcb & ~3) | ((b) + 1))))
118 
119 #endif /* _LP64 */
120 
121 
122 
123 /*
124  * switch between a node and data pointer for a given tree
125  * the value of "o" is tree->avl_offset
126  */
127 #define	AVL_NODE2DATA(n, o)	((void *)((uintptr_t)(n) - (o)))
128 #define	AVL_DATA2NODE(d, o)	((struct avl_node *)((uintptr_t)(d) + (o)))
129 
130 
131 
132 /*
133  * macros used to create/access an avl_index_t
134  */
135 #define	AVL_INDEX2NODE(x)	((avl_node_t *)((x) & ~1))
136 #define	AVL_INDEX2CHILD(x)	((x) & 1)
137 #define	AVL_MKINDEX(n, c)	((avl_index_t)(n) | (c))
138 
139 
140 /*
141  * The tree structure. The fields avl_root, avl_compar, and avl_offset come
142  * first since they are needed for avl_find().  We want them to fit into
143  * a single 64 byte cache line to make avl_find() as fast as possible.
144  */
145 struct avl_tree {
146 	struct avl_node *avl_root;	/* root node in tree */
147 	int (*avl_compar)(const void *, const void *);
148 	size_t avl_offset;		/* offsetof(type, avl_link_t field) */
149 	ulong_t avl_numnodes;		/* number of nodes in the tree */
150 #ifndef _KERNEL
151 	size_t avl_pad;			/* For backwards ABI compatibility. */
152 #endif
153 };
154 
155 
156 /*
157  * This will only by used via AVL_NEXT() or AVL_PREV()
158  */
159 _AVL_IMPL_H void *avl_walk(struct avl_tree *, void *, int);
160 
161 #ifdef	__cplusplus
162 }
163 #endif
164 
165 #endif	/* _AVL_IMPL_H */
166