| /* |
| 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/lib/rbtree.c |
| */ |
| |
| #include <linux/rbtree.h> |
| #include <linux/module.h> |
| |
| static void __rb_rotate_left(rb_node_t * node, rb_root_t * root) |
| { |
| rb_node_t * right = node->rb_right; |
| |
| if ((node->rb_right = right->rb_left)) |
| right->rb_left->rb_parent = node; |
| right->rb_left = node; |
| |
| if ((right->rb_parent = node->rb_parent)) |
| { |
| if (node == node->rb_parent->rb_left) |
| node->rb_parent->rb_left = right; |
| else |
| node->rb_parent->rb_right = right; |
| } |
| else |
| root->rb_node = right; |
| node->rb_parent = right; |
| } |
| |
| static void __rb_rotate_right(rb_node_t * node, rb_root_t * root) |
| { |
| rb_node_t * left = node->rb_left; |
| |
| if ((node->rb_left = left->rb_right)) |
| left->rb_right->rb_parent = node; |
| left->rb_right = node; |
| |
| if ((left->rb_parent = node->rb_parent)) |
| { |
| if (node == node->rb_parent->rb_right) |
| node->rb_parent->rb_right = left; |
| else |
| node->rb_parent->rb_left = left; |
| } |
| else |
| root->rb_node = left; |
| node->rb_parent = left; |
| } |
| |
| void rb_insert_color(rb_node_t * node, rb_root_t * root) |
| { |
| rb_node_t * parent, * gparent; |
| |
| while ((parent = node->rb_parent) && parent->rb_color == RB_RED) |
| { |
| gparent = parent->rb_parent; |
| |
| if (parent == gparent->rb_left) |
| { |
| { |
| register rb_node_t * uncle = gparent->rb_right; |
| if (uncle && uncle->rb_color == RB_RED) |
| { |
| uncle->rb_color = RB_BLACK; |
| parent->rb_color = RB_BLACK; |
| gparent->rb_color = RB_RED; |
| node = gparent; |
| continue; |
| } |
| } |
| |
| if (parent->rb_right == node) |
| { |
| register rb_node_t * tmp; |
| __rb_rotate_left(parent, root); |
| tmp = parent; |
| parent = node; |
| node = tmp; |
| } |
| |
| parent->rb_color = RB_BLACK; |
| gparent->rb_color = RB_RED; |
| __rb_rotate_right(gparent, root); |
| } else { |
| { |
| register rb_node_t * uncle = gparent->rb_left; |
| if (uncle && uncle->rb_color == RB_RED) |
| { |
| uncle->rb_color = RB_BLACK; |
| parent->rb_color = RB_BLACK; |
| gparent->rb_color = RB_RED; |
| node = gparent; |
| continue; |
| } |
| } |
| |
| if (parent->rb_left == node) |
| { |
| register rb_node_t * tmp; |
| __rb_rotate_right(parent, root); |
| tmp = parent; |
| parent = node; |
| node = tmp; |
| } |
| |
| parent->rb_color = RB_BLACK; |
| gparent->rb_color = RB_RED; |
| __rb_rotate_left(gparent, root); |
| } |
| } |
| |
| root->rb_node->rb_color = RB_BLACK; |
| } |
| EXPORT_SYMBOL(rb_insert_color); |
| |
| static void __rb_erase_color(rb_node_t * node, rb_node_t * parent, |
| rb_root_t * root) |
| { |
| rb_node_t * other; |
| |
| while ((!node || node->rb_color == RB_BLACK) && node != root->rb_node) |
| { |
| if (parent->rb_left == node) |
| { |
| other = parent->rb_right; |
| if (other->rb_color == RB_RED) |
| { |
| other->rb_color = RB_BLACK; |
| parent->rb_color = RB_RED; |
| __rb_rotate_left(parent, root); |
| other = parent->rb_right; |
| } |
| if ((!other->rb_left || |
| other->rb_left->rb_color == RB_BLACK) |
| && (!other->rb_right || |
| other->rb_right->rb_color == RB_BLACK)) |
| { |
| other->rb_color = RB_RED; |
| node = parent; |
| parent = node->rb_parent; |
| } |
| else |
| { |
| if (!other->rb_right || |
| other->rb_right->rb_color == RB_BLACK) |
| { |
| register rb_node_t * o_left; |
| if ((o_left = other->rb_left)) |
| o_left->rb_color = RB_BLACK; |
| other->rb_color = RB_RED; |
| __rb_rotate_right(other, root); |
| other = parent->rb_right; |
| } |
| other->rb_color = parent->rb_color; |
| parent->rb_color = RB_BLACK; |
| if (other->rb_right) |
| other->rb_right->rb_color = RB_BLACK; |
| __rb_rotate_left(parent, root); |
| node = root->rb_node; |
| break; |
| } |
| } |
| else |
| { |
| other = parent->rb_left; |
| if (other->rb_color == RB_RED) |
| { |
| other->rb_color = RB_BLACK; |
| parent->rb_color = RB_RED; |
| __rb_rotate_right(parent, root); |
| other = parent->rb_left; |
| } |
| if ((!other->rb_left || |
| other->rb_left->rb_color == RB_BLACK) |
| && (!other->rb_right || |
| other->rb_right->rb_color == RB_BLACK)) |
| { |
| other->rb_color = RB_RED; |
| node = parent; |
| parent = node->rb_parent; |
| } |
| else |
| { |
| if (!other->rb_left || |
| other->rb_left->rb_color == RB_BLACK) |
| { |
| register rb_node_t * o_right; |
| if ((o_right = other->rb_right)) |
| o_right->rb_color = RB_BLACK; |
| other->rb_color = RB_RED; |
| __rb_rotate_left(other, root); |
| other = parent->rb_left; |
| } |
| other->rb_color = parent->rb_color; |
| parent->rb_color = RB_BLACK; |
| if (other->rb_left) |
| other->rb_left->rb_color = RB_BLACK; |
| __rb_rotate_right(parent, root); |
| node = root->rb_node; |
| break; |
| } |
| } |
| } |
| if (node) |
| node->rb_color = RB_BLACK; |
| } |
| |
| void rb_erase(rb_node_t * node, rb_root_t * root) |
| { |
| rb_node_t * child, * parent; |
| int color; |
| |
| if (!node->rb_left) |
| child = node->rb_right; |
| else if (!node->rb_right) |
| child = node->rb_left; |
| else |
| { |
| rb_node_t * old = node, * left; |
| |
| node = node->rb_right; |
| while ((left = node->rb_left)) |
| node = left; |
| child = node->rb_right; |
| parent = node->rb_parent; |
| color = node->rb_color; |
| |
| if (child) |
| child->rb_parent = parent; |
| if (parent) |
| { |
| if (parent->rb_left == node) |
| parent->rb_left = child; |
| else |
| parent->rb_right = child; |
| } |
| else |
| root->rb_node = child; |
| |
| if (node->rb_parent == old) |
| parent = node; |
| node->rb_parent = old->rb_parent; |
| node->rb_color = old->rb_color; |
| node->rb_right = old->rb_right; |
| node->rb_left = old->rb_left; |
| |
| if (old->rb_parent) |
| { |
| if (old->rb_parent->rb_left == old) |
| old->rb_parent->rb_left = node; |
| else |
| old->rb_parent->rb_right = node; |
| } else |
| root->rb_node = node; |
| |
| old->rb_left->rb_parent = node; |
| if (old->rb_right) |
| old->rb_right->rb_parent = node; |
| goto color; |
| } |
| |
| parent = node->rb_parent; |
| color = node->rb_color; |
| |
| if (child) |
| child->rb_parent = 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); |
| } |
| EXPORT_SYMBOL(rb_erase); |
| |
| /* |
| * This function returns the first node (in sort order) of the tree. |
| */ |
| rb_node_t *rb_first(rb_root_t *root) |
| { |
| rb_node_t *n; |
| |
| n = root->rb_node; |
| if (!n) |
| return NULL; |
| while (n->rb_left) |
| n = n->rb_left; |
| return n; |
| } |
| EXPORT_SYMBOL(rb_first); |
| |
| rb_node_t *rb_last(rb_root_t *root) |
| { |
| rb_node_t *n; |
| |
| n = root->rb_node; |
| if (!n) |
| return NULL; |
| while (n->rb_right) |
| n = n->rb_right; |
| return n; |
| } |
| EXPORT_SYMBOL(rb_last); |
| |
| rb_node_t *rb_next(rb_node_t *node) |
| { |
| /* 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 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 (node->rb_parent && node == node->rb_parent->rb_right) |
| node = node->rb_parent; |
| |
| return node->rb_parent; |
| } |
| EXPORT_SYMBOL(rb_next); |
| |
| rb_node_t *rb_prev(rb_node_t *node) |
| { |
| /* 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 node; |
| } |
| |
| /* No left-hand children. Go up till we find an ancestor which |
| is a right-hand child of its parent */ |
| while (node->rb_parent && node == node->rb_parent->rb_left) |
| node = node->rb_parent; |
| |
| return node->rb_parent; |
| } |
| EXPORT_SYMBOL(rb_prev); |