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422 giacomo 1
/*
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  Red Black Trees
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  (C) 1999  Andrea Arcangeli <andrea@suse.de>
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  This program is free software; you can redistribute it and/or modify
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  it under the terms of the GNU General Public License as published by
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  the Free Software Foundation; either version 2 of the License, or
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  (at your option) any later version.
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  This program is distributed in the hope that it will be useful,
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  but WITHOUT ANY WARRANTY; without even the implied warranty of
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  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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  GNU General Public License for more details.
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  You should have received a copy of the GNU General Public License
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  along with this program; if not, write to the Free Software
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  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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  linux/include/linux/rbtree.h
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  To use rbtrees you'll have to implement your own insert and search cores.
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  This will avoid us to use callbacks and to drop drammatically performances.
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  I know it's not the cleaner way,  but in C (not in C++) to get
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  performances and genericity...
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  Some example of insert and search follows here. The search is a plain
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  normal search over an ordered tree. The insert instead must be implemented
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  int two steps: as first thing the code must insert the element in
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  order as a red leaf in the tree, then the support library function
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  rb_insert_color() must be called. Such function will do the
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  not trivial work to rebalance the rbtree if necessary.
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-----------------------------------------------------------------------
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static inline struct page * rb_search_page_cache(struct inode * inode,
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                                                 unsigned long offset)
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{
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        struct rb_node * n = inode->i_rb_page_cache.rb_node;
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        struct page * page;
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        while (n)
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        {
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                page = rb_entry(n, struct page, rb_page_cache);
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                if (offset < page->offset)
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                        n = n->rb_left;
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                else if (offset > page->offset)
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                        n = n->rb_right;
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                else
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                        return page;
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        }
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        return NULL;
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}
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static inline struct page * __rb_insert_page_cache(struct inode * inode,
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                                                   unsigned long offset,
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                                                   struct rb_node * node)
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{
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        struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
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        struct rb_node * parent = NULL;
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        struct page * page;
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        while (*p)
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        {
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                parent = *p;
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                page = rb_entry(parent, struct page, rb_page_cache);
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                if (offset < page->offset)
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                        p = &(*p)->rb_left;
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                else if (offset > page->offset)
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                        p = &(*p)->rb_right;
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                else
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                        return page;
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        }
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        rb_link_node(node, parent, p);
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        return NULL;
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}
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static inline struct page * rb_insert_page_cache(struct inode * inode,
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                                                 unsigned long offset,
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                                                 struct rb_node * node)
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{
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        struct page * ret;
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        if ((ret = __rb_insert_page_cache(inode, offset, node)))
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                goto out;
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        rb_insert_color(node, &inode->i_rb_page_cache);
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 out:
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        return ret;
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}
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-----------------------------------------------------------------------
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*/
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#ifndef _LINUX_RBTREE_H
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#define _LINUX_RBTREE_H
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#include <linux/kernel.h>
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#include <linux/stddef.h>
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struct rb_node
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{
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        struct rb_node *rb_parent;
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        int rb_color;
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#define RB_RED          0
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#define RB_BLACK        1
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        struct rb_node *rb_right;
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        struct rb_node *rb_left;
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};
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struct rb_root
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{
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        struct rb_node *rb_node;
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};
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#define RB_ROOT (struct rb_root) { NULL, }
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#define rb_entry(ptr, type, member)                                     \
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        ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))
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extern void rb_insert_color(struct rb_node *, struct rb_root *);
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extern void rb_erase(struct rb_node *, struct rb_root *);
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/* Find logical next and previous nodes in a tree */
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extern struct rb_node *rb_next(struct rb_node *);
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extern struct rb_node *rb_prev(struct rb_node *);
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extern struct rb_node *rb_first(struct rb_root *);
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/* Fast replacement of a single node without remove/rebalance/add/rebalance */
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extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
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                            struct rb_root *root);
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static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
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                                struct rb_node ** rb_link)
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{
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        node->rb_parent = parent;
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        node->rb_color = RB_RED;
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        node->rb_left = node->rb_right = NULL;
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        *rb_link = node;
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}
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#endif  /* _LINUX_RBTREE_H */