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/*

  Red Black Trees

  (C) 1999  Andrea Arcangeli 

  (C) 2002  David Woodhouse 

  (C) 2012  Michel Lespinasse 

  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_augmented.h

*/

#ifndef _LINUX_RBTREE_AUGMENTED_H

#define _LINUX_RBTREE_AUGMENTED_H

#include 

#include 

/*

 * Please note - only struct rb_augment_callbacks and the prototypes for

 * rb_insert_augmented() and rb_erase_augmented() are intended to be public.

 * The rest are implementation details you are not expected to depend on.

 *

 * See Documentation/rbtree.txt for documentation and samples.

 */

struct rb_augment_callbacks {

	void (*propagate)(struct rb_node *node, struct rb_node *stop);

	void (*copy)(struct rb_node *old, struct rb_node *new);

	void (*rotate)(struct rb_node *old, struct rb_node *new);

};

extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,

	void (*augment_rotate)(struct rb_node *old, struct rb_node *new));

/*

 * Fixup the rbtree and update the augmented information when rebalancing.

 *

 * On insertion, the user must update the augmented information on the path

 * leading to the inserted node, then call rb_link_node() as usual and

 * rb_augment_inserted() instead of the usual rb_insert_color() call.

 * If rb_augment_inserted() rebalances the rbtree, it will callback into

 * a user provided function to update the augmented information on the

 * affected subtrees.

 */

static inline void

rb_insert_augmented(struct rb_node *node, struct rb_root *root,

		    const struct rb_augment_callbacks *augment)

{

	__rb_insert_augmented(node, root, augment->rotate);

}

#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield,	\

			     rbtype, rbaugmented, rbcompute)		\

static inline void							\

rbname ## _propagate(struct rb_node *rb, struct rb_node *stop)		\

{									\

	while (rb != stop) {						\

		rbstruct *node = rb_entry(rb, rbstruct, rbfield);	\

		rbtype augmented = rbcompute(node);			\

		if (node->rbaugmented == augmented)			\

			break;						\

		node->rbaugmented = augmented;				\

		rb = rb_parent(&node->rbfield);				\

	}								\

}									\

static inline void							\

rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new)		\

{									\

	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);		\

	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);		\

	new->rbaugmented = old->rbaugmented;				\

}									\

static void								\

rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new)	\

{									\

	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield);		\

	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield);		\

	new->rbaugmented = old->rbaugmented;				\

	old->rbaugmented = rbcompute(old);				\

}									\

rbstatic const struct rb_augment_callbacks rbname = {			\

	rbname ## _propagate, rbname ## _copy, rbname ## _rotate	\

};

#define	RB_RED		0

#define	RB_BLACK	1

#define __rb_parent(pc)    ((struct rb_node *)(pc & ~3))

#define __rb_color(pc)     ((pc) & 1)

#define __rb_is_black(pc)  __rb_color(pc)

#define __rb_is_red(pc)    (!__rb_color(pc))

#define rb_color(rb)       __rb_color((rb)->__rb_parent_color)

#define rb_is_red(rb)      __rb_is_red((rb)->__rb_parent_color)

#define rb_is_black(rb)    __rb_is_black((rb)->__rb_parent_color)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)

{

	rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;

}

static inline void rb_set_parent_color(struct rb_node *rb,

				       struct rb_node *p, int color)

{

	rb->__rb_parent_color = (unsigned long)p | color;

}

static inline void

__rb_change_child(struct rb_node *old, struct rb_node *new,

		  struct rb_node *parent, struct rb_root *root)

{

	if (parent) {

		if (parent->rb_left == old)

			WRITE_ONCE(parent->rb_left, new);

		else

			WRITE_ONCE(parent->rb_right, new);

	} else

		WRITE_ONCE(root->rb_node, new);

}

extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,

	void (*augment_rotate)(struct rb_node *old, struct rb_node *new));

static __always_inline struct rb_node *

__rb_erase_augmented(struct rb_node *node, struct rb_root *root,

		     const struct rb_augment_callbacks *augment)

{

	struct rb_node *child = node->rb_right;

	struct rb_node *tmp = node->rb_left;

	struct rb_node *parent, *rebalance;

	unsigned long pc;

	if (!tmp) {

		/*

		 * Case 1: node to erase has no more than 1 child (easy!)

		 *

		 * Note that if there is one child it must be red due to 5)

		 * and node must be black due to 4). We adjust colors locally

		 * so as to bypass __rb_erase_color() later on.

		 */

		pc = node->__rb_parent_color;

		parent = __rb_parent(pc);

		__rb_change_child(node, child, parent, root);

		if (child) {

			child->__rb_parent_color = pc;

			rebalance = NULL;

		} else

			rebalance = __rb_is_black(pc) ? parent : NULL;

		tmp = parent;

	} else if (!child) {

		/* Still case 1, but this time the child is node->rb_left */

		tmp->__rb_parent_color = pc = node->__rb_parent_color;

		parent = __rb_parent(pc);

		__rb_change_child(node, tmp, parent, root);

		rebalance = NULL;

		tmp = parent;

	} else {

		struct rb_node *successor = child, *child2;

		tmp = child->rb_left;

		if (!tmp) {

			/*

			 * Case 2: node's successor is its right child

			 *

			 *    (n)          (s)

			 *    / \          / \

			 *  (x) (s)  ->  (x) (c)

			 *        \

			 *        (c)

			 */

			parent = successor;

			child2 = successor->rb_right;

			augment->copy(node, successor);

		} else {

			/*

			 * Case 3: node's successor is leftmost under

			 * node's right child subtree

			 *

			 *    (n)          (s)

			 *    / \          / \

			 *  (x) (y)  ->  (x) (y)

			 *      /            /

			 *    (p)          (p)

			 *    /            /

			 *  (s)          (c)

			 *    \

			 *    (c)

			 */

			do {

				parent = successor;

				successor = tmp;

				tmp = tmp->rb_left;

			} while (tmp);

			child2 = successor->rb_right;

			WRITE_ONCE(parent->rb_left, child2);

			WRITE_ONCE(successor->rb_right, child);

			rb_set_parent(child, successor);

			augment->copy(node, successor);

			augment->propagate(parent, successor);

		}

		tmp = node->rb_left;

		WRITE_ONCE(successor->rb_left, tmp);

		rb_set_parent(tmp, successor);

		pc = node->__rb_parent_color;

		tmp = __rb_parent(pc);

		__rb_change_child(node, successor, tmp, root);

		if (child2) {

			successor->__rb_parent_color = pc;

			rb_set_parent_color(child2, parent, RB_BLACK);

			rebalance = NULL;

		} else {

			unsigned long pc2 = successor->__rb_parent_color;

			successor->__rb_parent_color = pc;

			rebalance = __rb_is_black(pc2) ? parent : NULL;

		}

		tmp = successor;

	}

	augment->propagate(tmp, NULL);

	return rebalance;

}

static __always_inline void

rb_erase_augmented(struct rb_node *node, struct rb_root *root,

		   const struct rb_augment_callbacks *augment)

{

	struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);

	if (rebalance)

		__rb_erase_color(rebalance, root, augment->rotate);

}

#endif	/* _LINUX_RBTREE_AUGMENTED_H */