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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
+
+#pragma ident "%Z%%M% %I% %E% SMI"
+
+/*
+ * 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 */