1.rbtree.h
/* 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 in two steps: First, the code must insert the element in order as a red leaf in the tree, and 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 <linux/kernel.h> #include "stddef.h" 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 */ 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)) extern void rb_insert_color(struct rb_node *, struct rb_root *); extern void rb_erase(struct rb_node *, struct rb_root *); /* Find logical next and previous nodes in a tree */ extern struct rb_node *rb_next(const struct rb_node *); extern struct rb_node *rb_prev(const struct rb_node *); extern struct rb_node *rb_first(const struct rb_root *); extern struct rb_node *rb_last(const struct rb_root *); /* Fast replacement of a single node without remove/rebalance/add/rebalance */ extern 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; } #endif /* _LINUX_RBTREE_H */
2.rbtree.c
#include "rbtree.h" static void __rb_rotate_left(struct rb_node *node, struct rb_root *root) { struct rb_node *right = node->rb_right; struct rb_node *parent = rb_parent(node); if ((node->rb_right = right->rb_left)) rb_set_parent(right->rb_left, node); right->rb_left = node; rb_set_parent(right, parent); if (parent) { if (node == parent->rb_left) parent->rb_left = right; else parent->rb_right = right; } else root->rb_node = right; rb_set_parent(node, right); } static void __rb_rotate_right(struct rb_node *node, struct rb_root *root) { struct rb_node *left = node->rb_left; struct rb_node *parent = rb_parent(node); if ((node->rb_left = left->rb_right)) rb_set_parent(left->rb_right, node); left->rb_right = node; rb_set_parent(left, parent); if (parent) { if (node == parent->rb_right) parent->rb_right = left; else parent->rb_left = left; } else root->rb_node = left; rb_set_parent(node, left); } void rb_insert_color(struct rb_node *node, struct rb_root *root) { struct rb_node *parent, *gparent; while ((parent = rb_parent(node)) && rb_is_red(parent)) { gparent = rb_parent(parent); if (parent == gparent->rb_left) { { register struct rb_node *uncle = gparent->rb_right; if (uncle && rb_is_red(uncle)) { rb_set_black(uncle); rb_set_black(parent); rb_set_red(gparent); node = gparent; continue; } } if (parent->rb_right == node) { register struct rb_node *tmp; __rb_rotate_left(parent, root); tmp = parent; parent = node; node = tmp; } rb_set_black(parent); rb_set_red(gparent); __rb_rotate_right(gparent, root); } else { { register struct rb_node *uncle = gparent->rb_left; if (uncle && rb_is_red(uncle)) { rb_set_black(uncle); rb_set_black(parent); rb_set_red(gparent); node = gparent; continue; } } if (parent->rb_left == node) { register struct rb_node *tmp; __rb_rotate_right(parent, root); tmp = parent; parent = node; node = tmp; } rb_set_black(parent); rb_set_red(gparent); __rb_rotate_left(gparent, root); } } rb_set_black(root->rb_node); } static void __rb_erase_color(struct rb_node *node, struct rb_node *parent, struct rb_root *root) { struct rb_node *other; while ((!node || rb_is_black(node)) && node != root->rb_node) { if (parent->rb_left == node) { other = parent->rb_right; if (rb_is_red(other)) { rb_set_black(other); rb_set_red(parent); __rb_rotate_left(parent, root); other = parent->rb_right; } if ((!other->rb_left || rb_is_black(other->rb_left)) && (!other->rb_right || rb_is_black(other->rb_right))) { rb_set_red(other); node = parent; parent = rb_parent(node); } else { if (!other->rb_right || rb_is_black(other->rb_right)) { rb_set_black(other->rb_left); rb_set_red(other); __rb_rotate_right(other, root); other = parent->rb_right; } rb_set_color(other, rb_color(parent)); rb_set_black(parent); rb_set_black(other->rb_right); __rb_rotate_left(parent, root); node = root->rb_node; break; } } else { other = parent->rb_left; if (rb_is_red(other)) { rb_set_black(other); rb_set_red(parent); __rb_rotate_right(parent, root); other = parent->rb_left; } if ((!other->rb_left || rb_is_black(other->rb_left)) && (!other->rb_right || rb_is_black(other->rb_right))) { rb_set_red(other); node = parent; parent = rb_parent(node); } else { if (!other->rb_left || rb_is_black(other->rb_left)) { rb_set_black(other->rb_right); rb_set_red(other); __rb_rotate_left(other, root); other = parent->rb_left; } rb_set_color(other, rb_color(parent)); rb_set_black(parent); rb_set_black(other->rb_left); __rb_rotate_right(parent, root); node = root->rb_node; break; } } } if (node) rb_set_black(node); } void rb_erase(struct rb_node *node, struct rb_root *root) { struct rb_node *child, *parent; int color; if (!node->rb_left) child = node->rb_right; else if (!node->rb_right) child = node->rb_left; else { struct rb_node *old = node, *left; node = node->rb_right; while ((left = node->rb_left) != NULL) node = left; if (rb_parent(old)) { if (rb_parent(old)->rb_left == old) rb_parent(old)->rb_left = node; else rb_parent(old)->rb_right = node; } else root->rb_node = node; child = node->rb_right; parent = rb_parent(node); color = rb_color(node); if (parent == old) { parent = node; } else { if (child) rb_set_parent(child, parent); parent->rb_left = child; node->rb_right = old->rb_right; rb_set_parent(old->rb_right, node); } node->rb_parent_color = old->rb_parent_color; node->rb_left = old->rb_left; rb_set_parent(old->rb_left, node); goto color; } parent = rb_parent(node); color = rb_color(node); if (child) rb_set_parent(child, parent); if (parent) { if (parent->rb_left == node) parent->rb_left = child; else parent->rb_right = child; } else root->rb_node = child; color: if (color == RB_BLACK) __rb_erase_color(child, parent, root); } /* * This function returns the first node (in sort order) of the tree. */ struct rb_node *rb_first(const struct rb_root *root) { struct rb_node *n; n = root->rb_node; if (!n) return NULL; while (n->rb_left) n = n->rb_left; return n; } struct rb_node *rb_last(const struct rb_root *root) { struct rb_node *n; n = root->rb_node; if (!n) return NULL; while (n->rb_right) n = n->rb_right; return n; } struct rb_node *rb_next(const struct rb_node *node) { struct rb_node *parent; if (rb_parent(node) == node) return NULL; /* If we have a right-hand child, go down and then left as far as we can. */ if (node->rb_right) { node = node->rb_right; while (node->rb_left) node=node->rb_left; return (struct rb_node *)node; } /* No right-hand children. Everything down and left is smaller than us, so any 'next' node must be in the general direction of our parent. Go up the tree; any time the ancestor is a right-hand child of its parent, keep going up. First time it's a left-hand child of its parent, said parent is our 'next' node. */ while ((parent = rb_parent(node)) && node == parent->rb_right) node = parent; return parent; } struct rb_node *rb_prev(const struct rb_node *node) { struct rb_node *parent; if (rb_parent(node) == node) return NULL; /* If we have a left-hand child, go down and then right as far as we can. */ if (node->rb_left) { node = node->rb_left; while (node->rb_right) node=node->rb_right; return (struct rb_node *)node; } /* No left-hand children. Go up till we find an ancestor which is a right-hand child of its parent */ while ((parent = rb_parent(node)) && node == parent->rb_left) node = parent; return parent; } void rb_replace_node(struct rb_node *victim, struct rb_node *new, struct rb_root *root) { struct rb_node *parent = rb_parent(victim); /* Set the surrounding nodes to point to the replacement */ if (parent) { if (victim == parent->rb_left) parent->rb_left = new; else parent->rb_right = new; } else { root->rb_node = new; } if (victim->rb_left) rb_set_parent(victim->rb_left, new); if (victim->rb_right) rb_set_parent(victim->rb_right, new); /* Copy the pointers/colour from the victim to the replacement */ *new = *victim; }