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      1 /*
      2   Red Black Trees
      3   (C) 1999  Andrea Arcangeli <andrea (at) suse.de>
      4 
      5   This program is free software; you can redistribute it and/or modify
      6   it under the terms of the GNU General Public License as published by
      7   the Free Software Foundation; either version 2 of the License, or
      8   (at your option) any later version.
      9 
     10   This program is distributed in the hope that it will be useful,
     11   but WITHOUT ANY WARRANTY; without even the implied warranty of
     12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     13   GNU General Public License for more details.
     14 
     15   You should have received a copy of the GNU General Public License
     16   along with this program; if not, write to the Free Software
     17   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     18 
     19   linux/include/linux/rbtree.h
     20 
     21   To use rbtrees you'll have to implement your own insert and search cores.
     22   This will avoid us to use callbacks and to drop drammatically performances.
     23   I know it's not the cleaner way,  but in C (not in C++) to get
     24   performances and genericity...
     25 
     26   Some example of insert and search follows here. The search is a plain
     27   normal search over an ordered tree. The insert instead must be implemented
     28   in two steps: First, the code must insert the element in order as a red leaf
     29   in the tree, and then the support library function rb_insert_color() must
     30   be called. Such function will do the not trivial work to rebalance the
     31   rbtree, if necessary.
     32 
     33 -----------------------------------------------------------------------
     34 static inline struct page * rb_search_page_cache(struct inode * inode,
     35 						 unsigned long offset)
     36 {
     37 	struct rb_node * n = inode->i_rb_page_cache.rb_node;
     38 	struct page * page;
     39 
     40 	while (n)
     41 	{
     42 		page = rb_entry(n, struct page, rb_page_cache);
     43 
     44 		if (offset < page->offset)
     45 			n = n->rb_left;
     46 		else if (offset > page->offset)
     47 			n = n->rb_right;
     48 		else
     49 			return page;
     50 	}
     51 	return NULL;
     52 }
     53 
     54 static inline struct page * __rb_insert_page_cache(struct inode * inode,
     55 						   unsigned long offset,
     56 						   struct rb_node * node)
     57 {
     58 	struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
     59 	struct rb_node * parent = NULL;
     60 	struct page * page;
     61 
     62 	while (*p)
     63 	{
     64 		parent = *p;
     65 		page = rb_entry(parent, struct page, rb_page_cache);
     66 
     67 		if (offset < page->offset)
     68 			p = &(*p)->rb_left;
     69 		else if (offset > page->offset)
     70 			p = &(*p)->rb_right;
     71 		else
     72 			return page;
     73 	}
     74 
     75 	rb_link_node(node, parent, p);
     76 
     77 	return NULL;
     78 }
     79 
     80 static inline struct page * rb_insert_page_cache(struct inode * inode,
     81 						 unsigned long offset,
     82 						 struct rb_node * node)
     83 {
     84 	struct page * ret;
     85 	if ((ret = __rb_insert_page_cache(inode, offset, node)))
     86 		goto out;
     87 	rb_insert_color(node, &inode->i_rb_page_cache);
     88  out:
     89 	return ret;
     90 }
     91 -----------------------------------------------------------------------
     92 */
     93 
     94 #ifndef	_LINUX_RBTREE_H
     95 #define	_LINUX_RBTREE_H
     96 
     97 #include <stdlib.h>
     98 
     99 #undef offsetof
    100 #ifdef __compiler_offsetof
    101 #define offsetof(TYPE,MEMBER) __compiler_offsetof(TYPE,MEMBER)
    102 #else
    103 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
    104 #endif
    105 
    106 #define container_of(ptr, type, member) ({			\
    107 	const __typeof__( ((type *)0)->member ) *__mptr = (ptr);	\
    108 	(type *)( (char *)__mptr - offsetof(type,member) );})
    109 
    110 struct rb_node
    111 {
    112 	unsigned long  rb_parent_color;
    113 #define	RB_RED		0
    114 #define	RB_BLACK	1
    115 	struct rb_node *rb_right;
    116 	struct rb_node *rb_left;
    117 } __attribute__((aligned(sizeof(long))));
    118     /* The alignment might seem pointless, but allegedly CRIS needs it */
    119 
    120 struct rb_root
    121 {
    122 	struct rb_node *rb_node;
    123 };
    124 
    125 
    126 #define ext2fs_rb_parent(r)   ((struct rb_node *)((r)->rb_parent_color & ~3))
    127 #define ext2fs_rb_color(r)   ((r)->rb_parent_color & 1)
    128 #define ext2fs_rb_is_red(r)   (!ext2fs_rb_color(r))
    129 #define ext2fs_rb_is_black(r) ext2fs_rb_color(r)
    130 #define ext2fs_rb_set_red(r)  do { (r)->rb_parent_color &= ~1; } while (0)
    131 #define ext2fs_rb_set_black(r)  do { (r)->rb_parent_color |= 1; } while (0)
    132 
    133 static inline void ext2fs_rb_set_parent(struct rb_node *rb, struct rb_node *p)
    134 {
    135 	rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
    136 }
    137 static inline void ext2fs_rb_set_color(struct rb_node *rb, int color)
    138 {
    139 	rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
    140 }
    141 
    142 #define RB_ROOT	(struct rb_root) { NULL, }
    143 #define	ext2fs_rb_entry(ptr, type, member) container_of(ptr, type, member)
    144 
    145 #define EXT2FS_RB_EMPTY_ROOT(root)	((root)->rb_node == NULL)
    146 #define EXT2FS_RB_EMPTY_NODE(node)	(ext2fs_rb_parent(node) == node)
    147 #define EXT2FS_RB_CLEAR_NODE(node)	(ext2fs_rb_set_parent(node, node))
    148 
    149 extern void ext2fs_rb_insert_color(struct rb_node *, struct rb_root *);
    150 extern void ext2fs_rb_erase(struct rb_node *, struct rb_root *);
    151 
    152 typedef void (*rb_augment_f)(struct rb_node *node, void *data);
    153 
    154 extern void ext2fs_rb_augment_insert(struct rb_node *node,
    155 			      rb_augment_f func, void *data);
    156 extern struct rb_node *ext2fs_rb_augment_erase_begin(struct rb_node *node);
    157 extern void ext2fs_rb_augment_erase_end(struct rb_node *node,
    158 				 rb_augment_f func, void *data);
    159 
    160 /* Find logical next and previous nodes in a tree */
    161 extern struct rb_node *ext2fs_rb_next(struct rb_node *);
    162 extern struct rb_node *ext2fs_rb_prev(struct rb_node *);
    163 extern struct rb_node *ext2fs_rb_first(const struct rb_root *);
    164 extern struct rb_node *ext2fs_rb_last(const struct rb_root *);
    165 
    166 /* Fast replacement of a single node without remove/rebalance/add/rebalance */
    167 extern void ext2fs_rb_replace_node(struct rb_node *victim, struct rb_node *new,
    168 				 struct rb_root *root);
    169 
    170 static inline void ext2fs_rb_link_node(struct rb_node * node,
    171 				     struct rb_node * parent,
    172 				     struct rb_node ** rb_link)
    173 {
    174 	node->rb_parent_color = (unsigned long )parent;
    175 	node->rb_left = node->rb_right = NULL;
    176 
    177 	*rb_link = node;
    178 }
    179 
    180 #endif	/* _LINUX_RBTREE_H */
    181