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1101 jermar 1
/*
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 * Copyright (C) 2006 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#ifndef __BTREE_H__
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#define __BTREE_H__
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#include <arch/types.h>
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#include <typedefs.h>
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#include <adt/list.h>
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#define BTREE_M     5
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#define BTREE_MAX_KEYS  (BTREE_M - 1)
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typedef __u64 btree_key_t;
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/** B-tree node structure. */
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struct btree_node {
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    /** Number of keys. */
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    count_t keys;
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    /** Keys. We currently support only single keys. Additional room for one extra key is provided. */
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    btree_key_t key[BTREE_MAX_KEYS + 1];
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    /**
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     * Pointers to values. Sorted according to the key array. Defined only in leaf-level.
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     * There is room for storing value for the extra key.
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     */
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    void *value[BTREE_MAX_KEYS + 1];
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    /**
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     * Pointers to descendants of this node sorted according to the key array.
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     * subtree[0] points to subtree with keys lesser than to key[0].
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     * subtree[1] points to subtree with keys greater than or equal to key[0] and lesser than key[1].
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     * ...
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     * There is room for storing a subtree pointer for the extra key.
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     */
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    btree_node_t *subtree[BTREE_M + 1];
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    /** Pointer to parent node. Root node has NULL parent. */
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    btree_node_t *parent;
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    /** Link connecting leaf-level nodes. Defined only when this node is a leaf. */
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    link_t leaf_link;
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    /** Variables needed by btree_print(). */  
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    link_t bfs_link;
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    int depth;
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};
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/** B-tree structure. */
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struct btree {
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    btree_node_t *root; /**< B-tree root node pointer. */
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    link_t leaf_head;   /**< Leaf-level list head. */
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};
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extern void btree_init(void);
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extern void btree_create(btree_t *t);
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extern void btree_destroy(btree_t *t);
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extern void btree_insert(btree_t *t, btree_key_t key, void *value, btree_node_t *leaf_node);
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extern void btree_remove(btree_t *t, btree_key_t key, btree_node_t *leaf_node);
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extern void *btree_search(btree_t *t, btree_key_t key, btree_node_t **leaf_node);
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extern btree_node_t *btree_leaf_node_left_neighbour(btree_t *t, btree_node_t *node);
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extern btree_node_t *btree_leaf_node_right_neighbour(btree_t *t, btree_node_t *node);
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extern void btree_print(btree_t *t);
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#endif