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7f97c7ea9a
As we start refactoring the code to break dependencies (see doc/refactoring.txt), I want us to use full paths in the includes (eg, #include "base/data-struct/list.h"). This makes it more obvious when we're breaking abstraction boundaries, eg, including a file in metadata/ from base/
138 lines
2.5 KiB
C
138 lines
2.5 KiB
C
/*
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* Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
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* Copyright (C) 2004-2007 Red Hat, Inc. All rights reserved.
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*
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* This file is part of LVM2.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU Lesser General Public License v.2.1.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "lib/misc/lib.h"
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#include "lib/datastruct/btree.h"
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struct node {
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uint32_t key;
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struct node *l, *r, *p;
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void *data;
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};
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struct btree {
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struct dm_pool *mem;
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struct node *root;
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};
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struct btree *btree_create(struct dm_pool *mem)
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{
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struct btree *t = dm_pool_alloc(mem, sizeof(*t));
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if (t) {
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t->mem = mem;
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t->root = NULL;
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}
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return t;
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}
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/*
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* Shuffle the bits in a key, to try and remove
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* any ordering.
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*/
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static uint32_t _shuffle(uint32_t k)
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{
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#if 1
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return ((k & 0xff) << 24 |
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(k & 0xff00) << 8 |
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(k & 0xff0000) >> 8 | (k & 0xff000000) >> 24);
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#else
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return k;
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#endif
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}
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static struct node *const *_lookup(struct node *const *c, uint32_t key,
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struct node **p)
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{
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*p = NULL;
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while (*c) {
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*p = *c;
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if ((*c)->key == key)
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break;
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if (key < (*c)->key)
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c = &(*c)->l;
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else
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c = &(*c)->r;
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}
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return c;
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}
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void *btree_lookup(const struct btree *t, uint32_t k)
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{
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uint32_t key = _shuffle(k);
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struct node *p, *const *c = _lookup(&t->root, key, &p);
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return (*c) ? (*c)->data : NULL;
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}
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int btree_insert(struct btree *t, uint32_t k, void *data)
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{
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uint32_t key = _shuffle(k);
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struct node *p, **c = (struct node **) _lookup(&t->root, key, &p), *n;
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if (!*c) {
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if (!(n = dm_pool_alloc(t->mem, sizeof(*n))))
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return_0;
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n->key = key;
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n->data = data;
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n->l = n->r = NULL;
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n->p = p;
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*c = n;
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}
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return 1;
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}
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void *btree_get_data(const struct btree_iter *it)
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{
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return ((const struct node *) it)->data;
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}
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static struct node *_left(struct node *n)
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{
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while (n->l)
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n = n->l;
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return n;
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}
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struct btree_iter *btree_first(const struct btree *t)
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{
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if (!t->root)
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return NULL;
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return (struct btree_iter *) _left(t->root);
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}
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struct btree_iter *btree_next(const struct btree_iter *it)
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{
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struct node *n = (struct node *) it;
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uint32_t k = n->key;
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if (n->r)
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return (struct btree_iter *) _left(n->r);
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do
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n = n->p;
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while (n && k > n->key);
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return (struct btree_iter *) n;
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}
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