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 int two steps: as first thing the code must insert the element in 29 order as a red leaf in the tree, then the support library function 30 rb_insert_color() must be called. Such function will do the 31 not trivial work to rebalance the 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 #include <inttypes.h> 99 100 struct rb_node 101 { 102 intptr_t rb_parent_color; 103 #define RB_RED 0 104 #define RB_BLACK 1 105 struct rb_node *rb_right; 106 struct rb_node *rb_left; 107 } __attribute__((aligned(sizeof(long)))); 108 /* The alignment might seem pointless, but allegedly CRIS needs it */ 109 110 struct rb_root 111 { 112 struct rb_node *rb_node; 113 }; 114 115 116 #define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3)) 117 #define rb_color(r) ((r)->rb_parent_color & 1) 118 #define rb_is_red(r) (!rb_color(r)) 119 #define rb_is_black(r) rb_color(r) 120 #define rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0) 121 #define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0) 122 123 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) 124 { 125 rb->rb_parent_color = (rb->rb_parent_color & 3) | (uintptr_t)p; 126 } 127 static inline void rb_set_color(struct rb_node *rb, int color) 128 { 129 rb->rb_parent_color = (rb->rb_parent_color & ~1) | color; 130 } 131 132 #define RB_ROOT (struct rb_root) { NULL, } 133 #define rb_entry(ptr, type, member) container_of(ptr, type, member) 134 135 #define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL) 136 #define RB_EMPTY_NODE(node) (rb_parent(node) == node) 137 #define RB_CLEAR_NODE(node) (rb_set_parent(node, node)) 138 139 extern void rb_insert_color(struct rb_node *, struct rb_root *); 140 extern void rb_erase(struct rb_node *, struct rb_root *); 141 142 /* Find logical next and previous nodes in a tree */ 143 extern struct rb_node *rb_first(struct rb_root *); 144 extern struct rb_node *rb_next(const struct rb_node *); 145 146 static inline void rb_link_node(struct rb_node * node, struct rb_node * parent, 147 struct rb_node ** rb_link) 148 { 149 node->rb_parent_color = (uintptr_t)parent; 150 node->rb_left = node->rb_right = NULL; 151 152 *rb_link = node; 153 } 154 155 #endif /* _LINUX_RBTREE_H */ 156
