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  1. /*
  2.  * Copyright (C) 2006 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. #ifndef __BTREE_H__
  30. #define __BTREE_H__
  31.  
  32. #include <arch/types.h>
  33. #include <typedefs.h>
  34. #include <adt/list.h>
  35.  
  36. #define BTREE_M     5
  37. #define BTREE_MAX_KEYS  (BTREE_M - 1)
  38.  
  39. typedef __u64 btree_key_t;
  40.  
  41. /** B-tree node structure. */
  42. struct btree_node {
  43.     /** Number of keys. */
  44.     count_t keys;
  45.  
  46.     /** Keys. We currently support only single keys. Additional room for one extra key is provided. */
  47.     btree_key_t key[BTREE_MAX_KEYS + 1];
  48.  
  49.     /**
  50.      * Pointers to values. Sorted according to the key array. Defined only in leaf-level.
  51.      * There is room for storing value for the extra key.
  52.      */
  53.     void *value[BTREE_MAX_KEYS + 1];
  54.    
  55.     /**
  56.      * Pointers to descendants of this node sorted according to the key array.
  57.      * subtree[0] points to subtree with keys lesser than to key[0].
  58.      * subtree[1] points to subtree with keys greater than or equal to key[0] and lesser than key[1].
  59.      * ...
  60.      * There is room for storing a subtree pointer for the extra key.
  61.      */
  62.     btree_node_t *subtree[BTREE_M + 1];
  63.  
  64.     /** Pointer to parent node. Root node has NULL parent. */
  65.     btree_node_t *parent;
  66.  
  67.     /** Link connecting leaf-level nodes. Defined only when this node is a leaf. */
  68.     link_t leaf_link;
  69.  
  70.     /** Variables needed by btree_print(). */  
  71.     link_t bfs_link;
  72.     int depth;
  73. };
  74.  
  75. /** B-tree structure. */
  76. struct btree {
  77.     btree_node_t *root; /**< B-tree root node pointer. */
  78.     link_t leaf_head;   /**< Leaf-level list head. */
  79. };
  80.  
  81. extern void btree_init(void);
  82.  
  83. extern void btree_create(btree_t *t);
  84. extern void btree_destroy(btree_t *t);
  85.  
  86. extern void btree_insert(btree_t *t, btree_key_t key, void *value, btree_node_t *leaf_node);
  87. extern void btree_remove(btree_t *t, btree_key_t key, btree_node_t *leaf_node);
  88. extern void *btree_search(btree_t *t, btree_key_t key, btree_node_t **leaf_node);
  89.  
  90. extern btree_node_t *btree_leaf_node_left_neighbour(btree_t *t, btree_node_t *node);
  91. extern btree_node_t *btree_leaf_node_right_neighbour(btree_t *t, btree_node_t *node);
  92.  
  93. extern void btree_print(btree_t *t);
  94. #endif
  95.