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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. /** @addtogroup genericadt
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #ifndef KERN_BTREE_H_
  36. #define KERN_BTREE_H_
  37.  
  38. #include <arch/types.h>
  39. #include <adt/list.h>
  40.  
  41. #define BTREE_M     5
  42. #define BTREE_MAX_KEYS  (BTREE_M - 1)
  43.  
  44. typedef uint64_t btree_key_t;
  45.  
  46. /** B-tree node structure. */
  47. typedef struct btree_node {
  48.     /** Number of keys. */
  49.     count_t keys;
  50.  
  51.     /**
  52.      * Keys. We currently support only single keys. Additional room for one
  53.      * extra key is provided.
  54.      */
  55.     btree_key_t key[BTREE_MAX_KEYS + 1];
  56.  
  57.     /**
  58.      * Pointers to values. Sorted according to the key array. Defined only in
  59.      * leaf-level. There is room for storing value for the extra key.
  60.      */
  61.     void *value[BTREE_MAX_KEYS + 1];
  62.    
  63.     /**
  64.      * Pointers to descendants of this node sorted according to the key
  65.      * array.
  66.      *
  67.      * subtree[0] points to subtree with keys lesser than to key[0].
  68.      * subtree[1] points to subtree with keys greater than or equal to
  69.      *        key[0] and lesser than key[1].
  70.      * ...
  71.      * There is room for storing a subtree pointer for the extra key.
  72.      */
  73.     struct btree_node *subtree[BTREE_M + 1];
  74.  
  75.     /** Pointer to parent node. Root node has NULL parent. */
  76.     struct btree_node *parent;
  77.  
  78.     /**
  79.      * Link connecting leaf-level nodes. Defined only when this node is a
  80.      * leaf. */
  81.     link_t leaf_link;
  82.  
  83.     /* Variables needed by btree_print(). */   
  84.     link_t bfs_link;
  85.     int depth;
  86. } btree_node_t;
  87.  
  88. /** B-tree structure. */
  89. typedef struct {
  90.     btree_node_t *root; /**< B-tree root node pointer. */
  91.     link_t leaf_head;   /**< Leaf-level list head. */
  92. } btree_t;
  93.  
  94. extern void btree_init(void);
  95.  
  96. extern void btree_create(btree_t *t);
  97. extern void btree_destroy(btree_t *t);
  98.  
  99. extern void btree_insert(btree_t *t, btree_key_t key, void *value,
  100.     btree_node_t *leaf_node);
  101. extern void btree_remove(btree_t *t, btree_key_t key, btree_node_t *leaf_node);
  102. extern void *btree_search(btree_t *t, btree_key_t key, btree_node_t **leaf_node);
  103.  
  104. extern btree_node_t *btree_leaf_node_left_neighbour(btree_t *t,
  105.     btree_node_t *node);
  106. extern btree_node_t *btree_leaf_node_right_neighbour(btree_t *t,
  107.     btree_node_t *node);
  108.  
  109. extern void btree_print(btree_t *t);
  110. #endif
  111.  
  112. /** @}
  113.  */
  114.