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
