[mirror_ubuntu-bionic-kernel.git] / include / linux / rbtree_augmented.h

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  (C) 2012  Michel Lespinasse <walken@google.com>

  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 <linux/rbtree.h>

/*
 * 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));
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)
			parent->rb_left = new;
		else
			parent->rb_right = new;
	} else
		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 void
rb_erase_augmented(struct rb_node *node, struct rb_root *root,
		   const struct rb_augment_callbacks *augment)
{
	struct rb_node *child = node->rb_right, *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);
			parent->rb_left = child2 = successor->rb_right;
			successor->rb_right = child;
			rb_set_parent(child, successor);
			augment->copy(node, successor);
			augment->propagate(parent, successor);
		}

		successor->rb_left = tmp = node->rb_left;
		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);
	if (rebalance)
		__rb_erase_color(rebalance, root, augment->rotate);
}

#endif	/* _LINUX_RBTREE_AUGMENTED_H */
Commit	Line	Data
9c079add ML	1	/*
	2	Red Black Trees
	3	(C) 1999 Andrea Arcangeli <andrea@suse.de>
	4	(C) 2002 David Woodhouse <dwmw2@infradead.org>
	5	(C) 2012 Michel Lespinasse <walken@google.com>
	6
	7	This program is free software; you can redistribute it and/or modify
	8	it under the terms of the GNU General Public License as published by
	9	the Free Software Foundation; either version 2 of the License, or
	10	(at your option) any later version.
	11
	12	This program is distributed in the hope that it will be useful,
	13	but WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	15	GNU General Public License for more details.
	16
	17	You should have received a copy of the GNU General Public License
	18	along with this program; if not, write to the Free Software
	19	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	20
	21	linux/include/linux/rbtree_augmented.h
	22	*/
	23
	24	#ifndef _LINUX_RBTREE_AUGMENTED_H
	25	#define _LINUX_RBTREE_AUGMENTED_H
	26
	27	#include <linux/rbtree.h>
	28
	29	/*
	30	* Please note - only struct rb_augment_callbacks and the prototypes for
	31	* rb_insert_augmented() and rb_erase_augmented() are intended to be public.
	32	* The rest are implementation details you are not expected to depend on.
	33	*
	34	* See Documentation/rbtree.txt for documentation and samples.
	35	*/
	36
	37	struct rb_augment_callbacks {
	38	void (propagate)(struct rb_node node, struct rb_node *stop);
	39	void (copy)(struct rb_node old, struct rb_node *new);
	40	void (rotate)(struct rb_node old, struct rb_node *new);
	41	};
	42
	43	extern void __rb_insert_augmented(struct rb_node node, struct rb_root root,
	44	void (augment_rotate)(struct rb_node old, struct rb_node *new));
	45	static inline void
	46	rb_insert_augmented(struct rb_node node, struct rb_root root,
	47	const struct rb_augment_callbacks *augment)
	48	{
	49	__rb_insert_augmented(node, root, augment->rotate);
	50	}
	51
	52	#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
	53	rbtype, rbaugmented, rbcompute) \
	54	static inline void \
	55	rbname ## _propagate(struct rb_node rb, struct rb_node stop) \
	56	{ \
	57	while (rb != stop) { \
	58	rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
	59	rbtype augmented = rbcompute(node); \
	60	if (node->rbaugmented == augmented) \
	61	break; \
	62	node->rbaugmented = augmented; \
	63	rb = rb_parent(&node->rbfield); \
	64	} \
65	} \
66	static inline void \
67	rbname ## _copy(struct rb_node rb_old, struct rb_node rb_new) \
68	{ \
69	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
70	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
71	new->rbaugmented = old->rbaugmented; \
72	} \
73	static void \
74	rbname ## _rotate(struct rb_node rb_old, struct rb_node rb_new) \
75	{ \
76	rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
77	rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
78	new->rbaugmented = old->rbaugmented; \
79	old->rbaugmented = rbcompute(old); \
80	} \
81	rbstatic const struct rb_augment_callbacks rbname = { \
82	rbname ## _propagate, rbname ## _copy, rbname ## _rotate \
83	};
84
85
86	#define RB_RED 0
87	#define RB_BLACK 1
88
89	#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
90
91	#define __rb_color(pc) ((pc) & 1)
92	#define __rb_is_black(pc) __rb_color(pc)
93	#define __rb_is_red(pc) (!__rb_color(pc))
94	#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
95	#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
96	#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
97
98	static inline void rb_set_parent(struct rb_node rb, struct rb_node p)
99	{
100	rb->__rb_parent_color = rb_color(rb) \| (unsigned long)p;
101	}
102
103	static inline void rb_set_parent_color(struct rb_node *rb,
104	struct rb_node *p, int color)
105	{
106	rb->__rb_parent_color = (unsigned long)p \| color;
107	}
108
109	static inline void
110	__rb_change_child(struct rb_node old, struct rb_node new,
111	struct rb_node parent, struct rb_root root)
112	{
113	if (parent) {
114	if (parent->rb_left == old)
115	parent->rb_left = new;
116	else
117	parent->rb_right = new;
118	} else
119	root->rb_node = new;
120	}
121
122	extern void __rb_erase_color(struct rb_node parent, struct rb_root root,
123	void (augment_rotate)(struct rb_node old, struct rb_node *new));
124
125	static __always_inline void
126	rb_erase_augmented(struct rb_node node, struct rb_root root,
127	const struct rb_augment_callbacks *augment)
128	{
129	struct rb_node child = node->rb_right, tmp = node->rb_left;
130	struct rb_node parent, rebalance;
131	unsigned long pc;
132
133	if (!tmp) {
134	/*
135	* Case 1: node to erase has no more than 1 child (easy!)
136	*
137	* Note that if there is one child it must be red due to 5)
138	* and node must be black due to 4). We adjust colors locally
139	* so as to bypass __rb_erase_color() later on.
140	*/
141	pc = node->__rb_parent_color;
142	parent = __rb_parent(pc);
143	__rb_change_child(node, child, parent, root);
144	if (child) {
145	child->__rb_parent_color = pc;
146	rebalance = NULL;
147	} else
148	rebalance = __rb_is_black(pc) ? parent : NULL;
149	tmp = parent;
150	} else if (!child) {
151	/* Still case 1, but this time the child is node->rb_left */
152	tmp->__rb_parent_color = pc = node->__rb_parent_color;
153	parent = __rb_parent(pc);
154	__rb_change_child(node, tmp, parent, root);
155	rebalance = NULL;
156	tmp = parent;
157	} else {
158	struct rb_node successor = child, child2;
159	tmp = child->rb_left;
160	if (!tmp) {
161	/*
162	* Case 2: node's successor is its right child
163	*
164	* (n) (s)
165	* / \ / \
166	* (x) (s) -> (x) (c)
167	* \
168	* (c)
169	*/
170	parent = successor;
171	child2 = successor->rb_right;
172	augment->copy(node, successor);
173	} else {
174	/*
175	* Case 3: node's successor is leftmost under
176	* node's right child subtree
177	*
178	* (n) (s)
179	* / \ / \
180	* (x) (y) -> (x) (y)
181	* / /
182	* (p) (p)
183	* / /
184	* (s) (c)
185	* \
186	* (c)
187	*/
188	do {
189	parent = successor;
190	successor = tmp;
191	tmp = tmp->rb_left;
192	} while (tmp);
193	parent->rb_left = child2 = successor->rb_right;
194	successor->rb_right = child;
195	rb_set_parent(child, successor);
196	augment->copy(node, successor);
197	augment->propagate(parent, successor);
198	}
199
200	successor->rb_left = tmp = node->rb_left;
201	rb_set_parent(tmp, successor);
202
203	pc = node->__rb_parent_color;
204	tmp = __rb_parent(pc);
205	__rb_change_child(node, successor, tmp, root);
206	if (child2) {
207	successor->__rb_parent_color = pc;
208	rb_set_parent_color(child2, parent, RB_BLACK);
209	rebalance = NULL;
210	} else {
211	unsigned long pc2 = successor->__rb_parent_color;
212	successor->__rb_parent_color = pc;
213	rebalance = __rb_is_black(pc2) ? parent : NULL;
214	}
215	tmp = successor;
216	}
217
218	augment->propagate(tmp, NULL);
219	if (rebalance)
220	__rb_erase_color(rebalance, root, augment->rotate);
221	}
222
223	#endif /* _LINUX_RBTREE_AUGMENTED_H */