+/*
+ Red Black Trees
+ (C) 1999 Andrea Arcangeli <andrea@suse.de>
+ (C) 2002 David Woodhouse <dwmw2@infradead.org>
+
+ 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 "rbtree.h"
+
+static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
+{
+ struct rb_node *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(struct rb_node *node, struct rb_root *root)
+{
+ struct rb_node *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(struct rb_node *node, struct rb_root *root)
+{
+ struct rb_node *parent, *gparent;
+
+ while ((parent = node->rb_parent) && parent->rb_color == RB_RED)
+ {
+ gparent = parent->rb_parent;
+
+ if (parent == gparent->rb_left)
+ {
+ {
+ register struct rb_node *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 struct rb_node *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 struct rb_node *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 struct rb_node *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;
+}
+
+static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
+ struct rb_root *root)
+{
+ struct rb_node *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 struct rb_node *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 struct rb_node *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(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;
+ 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);
+}
+
+/*
+ * This function returns the first node (in sort order) of the tree.
+ */
+struct rb_node *rb_first(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(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(struct rb_node *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;
+}
+
+struct rb_node *rb_prev(struct rb_node *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;
+}
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