include/sys/avl_impl.h

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