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rbtree.h

/* Stolen from Linux 2.6.34 */

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

  linux/include/linux/rbtree.h

  To use rbtrees you'll have to implement your own insert and search cores.
  This will avoid us to use callbacks and to drop drammatically performances.
  I know it's not the cleaner way,  but in C (not in C++) to get
  performances and genericity...

  Some example of insert and search follows here. The search is a plain
  normal search over an ordered tree. The insert instead must be implemented
  int two steps: as first thing the code must insert the element in
  order as a red leaf in the tree, then the support library function
  rb_insert_color() must be called. Such function will do the
  not trivial work to rebalance the rbtree if necessary.

-----------------------------------------------------------------------
static inline struct page * rb_search_page_cache(struct inode * inode,
                                     unsigned long offset)
{
      struct rb_node * n = inode->i_rb_page_cache.rb_node;
      struct page * page;

      while (n)
      {
            page = rb_entry(n, struct page, rb_page_cache);

            if (offset < page->offset)
                  n = n->rb_left;
            else if (offset > page->offset)
                  n = n->rb_right;
            else
                  return page;
      }
      return NULL;
}

static inline struct page * __rb_insert_page_cache(struct inode * inode,
                                       unsigned long offset,
                                       struct rb_node * node)
{
      struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
      struct rb_node * parent = NULL;
      struct page * page;

      while (*p)
      {
            parent = *p;
            page = rb_entry(parent, struct page, rb_page_cache);

            if (offset < page->offset)
                  p = &(*p)->rb_left;
            else if (offset > page->offset)
                  p = &(*p)->rb_right;
            else
                  return page;
      }

      rb_link_node(node, parent, p);

      return NULL;
}

static inline struct page * rb_insert_page_cache(struct inode * inode,
                                     unsigned long offset,
                                     struct rb_node * node)
{
      struct page * ret;
      if ((ret = __rb_insert_page_cache(inode, offset, node)))
            goto out;
      rb_insert_color(node, &inode->i_rb_page_cache);
 out:
      return ret;
}
-----------------------------------------------------------------------
*/

#ifndef     _LINUX_RBTREE_H
#define     _LINUX_RBTREE_H

#include "compiler.h" /* container_of */
#include <stddef.h>

00102 struct rb_node
{
      unsigned long  rb_parent_color;
#define     RB_RED            0
#define     RB_BLACK    1
      struct rb_node *rb_right;
      struct rb_node *rb_left;
} __attribute__((aligned(sizeof(long))));
    /* The alignment might seem pointless, but allegedly CRIS needs it */

00112 struct rb_root
{
      struct rb_node *rb_node;
};


#define rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
#define rb_color(r)   ((r)->rb_parent_color & 1)
#define rb_is_red(r)   (!rb_color(r))
#define rb_is_black(r) rb_color(r)
#define rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
#define rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
{
      rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
}
static inline void rb_set_color(struct rb_node *rb, int color)
{
      rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
}

#define RB_ROOT   (struct rb_root) { NULL, }
#define     rb_entry(ptr, type, member) container_of(ptr, type, member)

#define RB_EMPTY_ROOT(root)   ((root)->rb_node == NULL)
#define RB_EMPTY_NODE(node)   (rb_parent(node) == node)
#define RB_CLEAR_NODE(node)   (rb_set_parent(node, node))

void rb_insert_color(struct rb_node *, struct rb_root *);
void rb_erase(struct rb_node *, struct rb_root *);

/* Find logical next and previous nodes in a tree */
struct rb_node *rb_next(const struct rb_node *);
struct rb_node *rb_prev(const struct rb_node *);
struct rb_node *rb_first(const struct rb_root *);
struct rb_node *rb_last(const struct rb_root *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */
void rb_replace_node(struct rb_node *victim, struct rb_node *new, 
                  struct rb_root *root);

static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
                        struct rb_node ** rb_link)
{
      node->rb_parent_color = (unsigned long )parent;
      node->rb_left = node->rb_right = NULL;

      *rb_link = node;
}


/* Cmus extensions */

static inline void rb_root_init(struct rb_root *root)
{
      root->rb_node = NULL;
}

static inline int rb_root_empty(struct rb_root *root)
{
      return RB_EMPTY_ROOT(root);
}

/**
 * rb_for_each        -       iterate over a rbtree
 * @pos:        the &struct rb_node to use as a loop counter.
 * @root:       the root for your rbtree.
 */
#define rb_for_each(pos, root) \
      for (pos = rb_first(root); pos; pos = rb_next(pos))

/**
 * rb_for_each_prev   -       iterate over a rbtree backwards
 * @pos:        the &struct rb_node to use as a loop counter.
 * @root:       the root for your rbtree.
 */
#define rb_for_each_prev(pos, root) \
      for (pos = rb_last(root); pos; pos = rb_prev(pos))

/**
 * rb_for_each_safe   -       iterate over a rbtree safe against removal of rbtree node
 * @pos:        the &struct rb_node to use as a loop counter.
 * @n:          another &struct rb_node to use as temporary storage
 * @root:       the root for your rbtree.
 */
#define rb_for_each_safe(pos, n, root) \
      for (pos = rb_first(root), n = pos ? rb_next(pos) : NULL; pos; \
            pos = n, n = pos ? rb_next(pos) : NULL)

/**
 * rb_for_each_entry        -       iterate over a rbtree of given type
 * @pos:        the &struct rb_node to use as a loop counter.
 * @t:          the type * to use as a loop counter.
 * @root:       the root for your rbtree.
 * @member: the name of the rb_node-struct within the struct.
 */
#define rb_for_each_entry(t, pos, root, member) \
      for (pos = rb_first(root), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL; \
            pos; pos = rb_next(pos), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL)

/**
 * rb_for_each_entry_reverse        -       iterate backwards over a rbtree of given type
 * @pos:        the &struct rb_node to use as a loop counter.
 * @t:          the type * to use as a loop counter.
 * @root:       the root for your rbtree.
 * @member: the name of the rb_node-struct within the struct.
 */
#define rb_for_each_entry_reverse(t, pos, root, member) \
      for (pos = rb_last(root), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL; \
            pos; pos = rb_prev(pos), t = pos ? rb_entry(pos, __typeof__(*t), member) : NULL)

#endif      /* _LINUX_RBTREE_H */

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