[linux.git] / lib / rbtree.c

/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <[email protected]>
  (C) 2002  David Woodhouse <[email protected]>
  
  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(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);
}
EXPORT_SYMBOL(rb_insert_color);

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))
				{
					struct rb_node *o_left;
					if ((o_left = other->rb_left))
						rb_set_black(o_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);
				if (other->rb_right)
					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))
				{
					register struct rb_node *o_right;
					if ((o_right = other->rb_right))
						rb_set_black(o_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);
				if (other->rb_left)
					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;
		child = node->rb_right;
		parent = rb_parent(node);
		color = rb_color(node);

		if (child)
			rb_set_parent(child, parent);
		if (parent == old) {
			parent->rb_right = child;
			parent = node;
		} else
			parent->rb_left = child;

		node->rb_parent_color = old->rb_parent_color;
		node->rb_right = old->rb_right;
		node->rb_left = old->rb_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;

		rb_set_parent(old->rb_left, node);
		if (old->rb_right)
			rb_set_parent(old->rb_right, 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);
}
EXPORT_SYMBOL(rb_erase);

/*
 * 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;
}
EXPORT_SYMBOL(rb_first);

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;
}
EXPORT_SYMBOL(rb_last);

struct rb_node *rb_next(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 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;
}
EXPORT_SYMBOL(rb_next);

struct rb_node *rb_prev(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 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;
}
EXPORT_SYMBOL(rb_prev);

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;
}
EXPORT_SYMBOL(rb_replace_node);
Commit	Line	Data
1da177e4 LT	1	/*
	2	Red Black Trees
	3	(C) 1999 Andrea Arcangeli <[email protected]>
	4	(C) 2002 David Woodhouse <[email protected]>
	5
	6	This program is free software; you can redistribute it and/or modify
	7	it under the terms of the GNU General Public License as published by
	8	the Free Software Foundation; either version 2 of the License, or
	9	(at your option) any later version.
	10
	11	This program is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	GNU General Public License for more details.
	15
	16	You should have received a copy of the GNU General Public License
	17	along with this program; if not, write to the Free Software
	18	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	19
	20	linux/lib/rbtree.c
	21	*/
	22
	23	#include <linux/rbtree.h>
	24	#include <linux/module.h>
	25
	26	static void __rb_rotate_left(struct rb_node node, struct rb_root root)
	27	{
	28	struct rb_node *right = node->rb_right;
55a98102	29	struct rb_node *parent = rb_parent(node);
1da177e4 LT	30
1da177e4 LT	31	if ((node->rb_right = right->rb_left))
55a98102	32	rb_set_parent(right->rb_left, node);
1da177e4 LT	33	right->rb_left = node;
1da177e4 LT	34
55a98102 DW	35	rb_set_parent(right, parent);
	36
	37	if (parent)
1da177e4	38	{
55a98102 DW	39	if (node == parent->rb_left)
55a98102 DW	40	parent->rb_left = right;
1da177e4	41	else
55a98102	42	parent->rb_right = right;
1da177e4 LT	43	}
	44	else
	45	root->rb_node = right;
55a98102	46	rb_set_parent(node, right);
1da177e4 LT	47	}
	48
	49	static void __rb_rotate_right(struct rb_node node, struct rb_root root)
	50	{
	51	struct rb_node *left = node->rb_left;
55a98102	52	struct rb_node *parent = rb_parent(node);
1da177e4 LT	53
1da177e4 LT	54	if ((node->rb_left = left->rb_right))
55a98102	55	rb_set_parent(left->rb_right, node);
1da177e4 LT	56	left->rb_right = node;
1da177e4 LT	57
55a98102 DW	58	rb_set_parent(left, parent);
	59
	60	if (parent)
1da177e4	61	{
55a98102 DW	62	if (node == parent->rb_right)
55a98102 DW	63	parent->rb_right = left;
1da177e4	64	else
55a98102	65	parent->rb_left = left;
1da177e4 LT	66	}
	67	else
	68	root->rb_node = left;
55a98102	69	rb_set_parent(node, left);
1da177e4 LT	70	}
	71
	72	void rb_insert_color(struct rb_node node, struct rb_root root)
	73	{
	74	struct rb_node parent, gparent;
	75
55a98102	76	while ((parent = rb_parent(node)) && rb_is_red(parent))
1da177e4	77	{
55a98102	78	gparent = rb_parent(parent);
1da177e4 LT	79
	80	if (parent == gparent->rb_left)
	81	{
	82	{
	83	register struct rb_node *uncle = gparent->rb_right;
55a98102	84	if (uncle && rb_is_red(uncle))
1da177e4	85	{
55a98102 DW	86	rb_set_black(uncle);
	87	rb_set_black(parent);
	88	rb_set_red(gparent);
1da177e4 LT	89	node = gparent;
	90	continue;
	91	}
	92	}
	93
	94	if (parent->rb_right == node)
	95	{
	96	register struct rb_node *tmp;
	97	__rb_rotate_left(parent, root);
	98	tmp = parent;
	99	parent = node;
	100	node = tmp;
	101	}
	102
55a98102 DW	103	rb_set_black(parent);
55a98102 DW	104	rb_set_red(gparent);
1da177e4 LT	105	__rb_rotate_right(gparent, root);
	106	} else {
	107	{
	108	register struct rb_node *uncle = gparent->rb_left;
55a98102	109	if (uncle && rb_is_red(uncle))
1da177e4	110	{
55a98102 DW	111	rb_set_black(uncle);
	112	rb_set_black(parent);
	113	rb_set_red(gparent);
1da177e4 LT	114	node = gparent;
	115	continue;
	116	}
	117	}
	118
	119	if (parent->rb_left == node)
	120	{
	121	register struct rb_node *tmp;
	122	__rb_rotate_right(parent, root);
	123	tmp = parent;
	124	parent = node;
	125	node = tmp;
	126	}
	127
55a98102 DW	128	rb_set_black(parent);
55a98102 DW	129	rb_set_red(gparent);
1da177e4 LT	130	__rb_rotate_left(gparent, root);
	131	}
	132	}
	133
55a98102	134	rb_set_black(root->rb_node);
1da177e4 LT	135	}
	136	EXPORT_SYMBOL(rb_insert_color);
	137
	138	static void __rb_erase_color(struct rb_node node, struct rb_node parent,
	139	struct rb_root *root)
	140	{
	141	struct rb_node *other;
	142
55a98102	143	while ((!node \|\| rb_is_black(node)) && node != root->rb_node)
1da177e4 LT	144	{
	145	if (parent->rb_left == node)
	146	{
	147	other = parent->rb_right;
55a98102	148	if (rb_is_red(other))
1da177e4	149	{
55a98102 DW	150	rb_set_black(other);
55a98102 DW	151	rb_set_red(parent);
1da177e4 LT	152	__rb_rotate_left(parent, root);
	153	other = parent->rb_right;
	154	}
55a98102 DW	155	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	156	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	157	{
55a98102	158	rb_set_red(other);
1da177e4	159	node = parent;
55a98102	160	parent = rb_parent(node);
1da177e4 LT	161	}
	162	else
	163	{
55a98102	164	if (!other->rb_right \|\| rb_is_black(other->rb_right))
1da177e4	165	{
55a98102	166	struct rb_node *o_left;
1da177e4	167	if ((o_left = other->rb_left))
55a98102 DW	168	rb_set_black(o_left);
55a98102 DW	169	rb_set_red(other);
1da177e4 LT	170	__rb_rotate_right(other, root);
	171	other = parent->rb_right;
	172	}
2f3243ae	173	rb_set_color(other, rb_color(parent));
55a98102	174	rb_set_black(parent);
1da177e4	175	if (other->rb_right)
55a98102	176	rb_set_black(other->rb_right);
1da177e4 LT	177	__rb_rotate_left(parent, root);
	178	node = root->rb_node;
	179	break;
	180	}
	181	}
	182	else
	183	{
	184	other = parent->rb_left;
55a98102	185	if (rb_is_red(other))
1da177e4	186	{
55a98102 DW	187	rb_set_black(other);
55a98102 DW	188	rb_set_red(parent);
1da177e4 LT	189	__rb_rotate_right(parent, root);
	190	other = parent->rb_left;
	191	}
55a98102 DW	192	if ((!other->rb_left \|\| rb_is_black(other->rb_left)) &&
55a98102 DW	193	(!other->rb_right \|\| rb_is_black(other->rb_right)))
1da177e4	194	{
55a98102	195	rb_set_red(other);
1da177e4	196	node = parent;
55a98102	197	parent = rb_parent(node);
1da177e4 LT	198	}
	199	else
	200	{
55a98102	201	if (!other->rb_left \|\| rb_is_black(other->rb_left))
1da177e4 LT	202	{
	203	register struct rb_node *o_right;
	204	if ((o_right = other->rb_right))
55a98102 DW	205	rb_set_black(o_right);
55a98102 DW	206	rb_set_red(other);
1da177e4 LT	207	__rb_rotate_left(other, root);
	208	other = parent->rb_left;
	209	}
2f3243ae	210	rb_set_color(other, rb_color(parent));
55a98102	211	rb_set_black(parent);
1da177e4	212	if (other->rb_left)
55a98102	213	rb_set_black(other->rb_left);
1da177e4 LT	214	__rb_rotate_right(parent, root);
	215	node = root->rb_node;
	216	break;
	217	}
	218	}
	219	}
	220	if (node)
55a98102	221	rb_set_black(node);
1da177e4 LT	222	}
	223
	224	void rb_erase(struct rb_node node, struct rb_root root)
	225	{
	226	struct rb_node child, parent;
	227	int color;
	228
	229	if (!node->rb_left)
	230	child = node->rb_right;
	231	else if (!node->rb_right)
	232	child = node->rb_left;
	233	else
	234	{
	235	struct rb_node old = node, left;
	236
	237	node = node->rb_right;
	238	while ((left = node->rb_left) != NULL)
	239	node = left;
	240	child = node->rb_right;
55a98102	241	parent = rb_parent(node);
2f3243ae	242	color = rb_color(node);
1da177e4 LT	243
1da177e4 LT	244	if (child)
55a98102 DW	245	rb_set_parent(child, parent);
55a98102 DW	246	if (parent == old) {
1975e593	247	parent->rb_right = child;
1da177e4	248	parent = node;
55a98102	249	} else
1975e593 DW	250	parent->rb_left = child;
1975e593 DW	251
2f3243ae	252	node->rb_parent_color = old->rb_parent_color;
1da177e4 LT	253	node->rb_right = old->rb_right;
	254	node->rb_left = old->rb_left;
	255
55a98102	256	if (rb_parent(old))
1da177e4	257	{
55a98102 DW	258	if (rb_parent(old)->rb_left == old)
55a98102 DW	259	rb_parent(old)->rb_left = node;
1da177e4	260	else
55a98102	261	rb_parent(old)->rb_right = node;
1da177e4 LT	262	} else
	263	root->rb_node = node;
	264
55a98102	265	rb_set_parent(old->rb_left, node);
1da177e4	266	if (old->rb_right)
55a98102	267	rb_set_parent(old->rb_right, node);
1da177e4 LT	268	goto color;
	269	}
	270
55a98102	271	parent = rb_parent(node);
2f3243ae	272	color = rb_color(node);
1da177e4 LT	273
1da177e4 LT	274	if (child)
55a98102	275	rb_set_parent(child, parent);
1da177e4 LT	276	if (parent)
	277	{
	278	if (parent->rb_left == node)
	279	parent->rb_left = child;
	280	else
	281	parent->rb_right = child;
	282	}
	283	else
	284	root->rb_node = child;
	285
	286	color:
	287	if (color == RB_BLACK)
	288	__rb_erase_color(child, parent, root);
	289	}
	290	EXPORT_SYMBOL(rb_erase);
	291
	292	/*
	293	* This function returns the first node (in sort order) of the tree.
	294	*/
	295	struct rb_node rb_first(struct rb_root root)
	296	{
	297	struct rb_node *n;
	298
	299	n = root->rb_node;
	300	if (!n)
	301	return NULL;
	302	while (n->rb_left)
	303	n = n->rb_left;
	304	return n;
	305	}
	306	EXPORT_SYMBOL(rb_first);
	307
	308	struct rb_node rb_last(struct rb_root root)
	309	{
	310	struct rb_node *n;
	311
	312	n = root->rb_node;
	313	if (!n)
	314	return NULL;
	315	while (n->rb_right)
	316	n = n->rb_right;
	317	return n;
	318	}
	319	EXPORT_SYMBOL(rb_last);
	320
	321	struct rb_node rb_next(struct rb_node node)
	322	{
55a98102 DW	323	struct rb_node *parent;
55a98102 DW	324
10fd48f2 JA	325	if (rb_parent(node) == node)
	326	return NULL;
	327
1da177e4 LT	328	/* If we have a right-hand child, go down and then left as far
	329	as we can. */
	330	if (node->rb_right) {
	331	node = node->rb_right;
	332	while (node->rb_left)
	333	node=node->rb_left;
	334	return node;
	335	}
	336
	337	/* No right-hand children. Everything down and left is
	338	smaller than us, so any 'next' node must be in the general
	339	direction of our parent. Go up the tree; any time the
	340	ancestor is a right-hand child of its parent, keep going
	341	up. First time it's a left-hand child of its parent, said
	342	parent is our 'next' node. */
55a98102 DW	343	while ((parent = rb_parent(node)) && node == parent->rb_right)
55a98102 DW	344	node = parent;
1da177e4	345
55a98102	346	return parent;
1da177e4 LT	347	}
	348	EXPORT_SYMBOL(rb_next);
	349
	350	struct rb_node rb_prev(struct rb_node node)
	351	{
55a98102 DW	352	struct rb_node *parent;
55a98102 DW	353
10fd48f2 JA	354	if (rb_parent(node) == node)
	355	return NULL;
	356
1da177e4 LT	357	/* If we have a left-hand child, go down and then right as far
	358	as we can. */
	359	if (node->rb_left) {
	360	node = node->rb_left;
	361	while (node->rb_right)
	362	node=node->rb_right;
	363	return node;
	364	}
	365
	366	/* No left-hand children. Go up till we find an ancestor which
	367	is a right-hand child of its parent */
55a98102 DW	368	while ((parent = rb_parent(node)) && node == parent->rb_left)
55a98102 DW	369	node = parent;
1da177e4	370
55a98102	371	return parent;
1da177e4 LT	372	}
	373	EXPORT_SYMBOL(rb_prev);
	374
	375	void rb_replace_node(struct rb_node victim, struct rb_node new,
	376	struct rb_root *root)
	377	{
55a98102	378	struct rb_node *parent = rb_parent(victim);
1da177e4 LT	379
	380	/* Set the surrounding nodes to point to the replacement */
	381	if (parent) {
	382	if (victim == parent->rb_left)
	383	parent->rb_left = new;
	384	else
	385	parent->rb_right = new;
	386	} else {
	387	root->rb_node = new;
	388	}
	389	if (victim->rb_left)
55a98102	390	rb_set_parent(victim->rb_left, new);
1da177e4	391	if (victim->rb_right)
55a98102	392	rb_set_parent(victim->rb_right, new);
1da177e4 LT	393
	394	/* Copy the pointers/colour from the victim to the replacement */
	395	new = victim;
	396	}
	397	EXPORT_SYMBOL(rb_replace_node);