1 /* $NetBSD: btree.c,v 1.1.1.1 2008/12/22 00:17:54 haad Exp $ */
4 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
5 * Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
7 * This file is part of LVM2.
9 * This copyrighted material is made available to anyone wishing to use,
10 * modify, copy, or redistribute it subject to the terms and conditions
11 * of the GNU Lesser General Public License v.2.1.
13 * You should have received a copy of the GNU Lesser General Public License
14 * along with this program; if not, write to the Free Software Foundation,
15 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 struct node *l, *r, *p;
33 struct btree *btree_create(struct dm_pool *mem)
35 struct btree *t = dm_pool_alloc(mem, sizeof(*t));
46 * Shuffle the bits in a key, to try and remove
49 static uint32_t _shuffle(uint32_t k)
52 return ((k & 0xff) << 24 |
54 (k & 0xff0000) >> 8 | (k & 0xff000000) >> 24);
60 static struct node **_lookup(struct node *const *c, uint32_t key,
76 return (struct node **)c;
79 void *btree_lookup(const struct btree *t, uint32_t k)
81 uint32_t key = _shuffle(k);
82 struct node *p, **c = _lookup(&t->root, key, &p);
83 return (*c) ? (*c)->data : NULL;
86 int btree_insert(struct btree *t, uint32_t k, void *data)
88 uint32_t key = _shuffle(k);
89 struct node *p, **c = _lookup(&t->root, key, &p), *n;
92 if (!(n = dm_pool_alloc(t->mem, sizeof(*n))))
106 void *btree_get_data(const struct btree_iter *it)
108 return ((struct node *) it)->data;
111 static struct node *_left(struct node *n)
118 struct btree_iter *btree_first(const struct btree *t)
123 return (struct btree_iter *) _left(t->root);
126 struct btree_iter *btree_next(const struct btree_iter *it)
128 struct node *n = (struct node *) it;
132 return (struct btree_iter *) _left(n->r);
136 while (n && k > n->key);
138 return (struct btree_iter *) n;