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 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 */