1 files changed, 215 insertions, 0 deletions
diff --git a/include/linux/interval_tree_tmpl.h b/include/linux/interval_tree_tmpl.h
new file mode 100644
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+++ b/include/linux/interval_tree_tmpl.h
@@ -0,0 +1,215 @@
+/*
+  Interval Trees
+  (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
+
+  include/linux/interval_tree_tmpl.h
+*/
+
+/*
+ * Template for implementing interval trees
+ *
+ * ITSTRUCT:   struct type of the interval tree nodes
+ * ITRB:       name of struct rb_node field within ITSTRUCT
+ * ITTYPE:     type of the interval endpoints
+ * ITSUBTREE:  name of ITTYPE field within ITSTRUCT holding last-in-subtree
+ * ITSTART(n): start endpoint of ITSTRUCT node n
+ * ITLAST(n):  last endpoing of ITSTRUCT node n
+ * ITSTATIC:   'static' or empty
+ * ITPREFIX:   prefix to use for the inline tree definitions
+ */
+
+/* IT(name) -> ITPREFIX_name */
+#define _ITNAME(prefix, name) prefix ## _ ## name
+#define ITNAME(prefix, name) _ITNAME(prefix, name)
+#define IT(name) ITNAME(ITPREFIX, name)
+
+/* Callbacks for augmented rbtree insert and remove */
+
+static inline ITTYPE IT(compute_subtree_last)(ITSTRUCT *node)
+{
+	ITTYPE max = ITLAST(node), subtree_last;
+	if (node->ITRB.rb_left) {
+		subtree_last = rb_entry(node->ITRB.rb_left,
+					ITSTRUCT, ITRB)->ITSUBTREE;
+		if (max < subtree_last)
+			max = subtree_last;
+	}
+	if (node->ITRB.rb_right) {
+		subtree_last = rb_entry(node->ITRB.rb_right,
+					ITSTRUCT, ITRB)->ITSUBTREE;
+		if (max < subtree_last)
+			max = subtree_last;
+	}
+	return max;
+}
+
+static void IT(augment_propagate)(struct rb_node *rb, struct rb_node *stop)
+{
+	while (rb != stop) {
+		ITSTRUCT *node = rb_entry(rb, ITSTRUCT, ITRB);
+		ITTYPE subtree_last = IT(compute_subtree_last)(node);
+		if (node->ITSUBTREE == subtree_last)
+			break;
+		node->ITSUBTREE = subtree_last;
+		rb = rb_parent(&node->ITRB);
+	}
+}
+
+static void IT(augment_copy)(struct rb_node *rb_old, struct rb_node *rb_new)
+{
+	ITSTRUCT *old = rb_entry(rb_old, ITSTRUCT, ITRB);
+	ITSTRUCT *new = rb_entry(rb_new, ITSTRUCT, ITRB);
+
+	new->ITSUBTREE = old->ITSUBTREE;
+}
+
+static void IT(augment_rotate)(struct rb_node *rb_old, struct rb_node *rb_new)
+{
+	ITSTRUCT *old = rb_entry(rb_old, ITSTRUCT, ITRB);
+	ITSTRUCT *new = rb_entry(rb_new, ITSTRUCT, ITRB);
+
+	new->ITSUBTREE = old->ITSUBTREE;
+	old->ITSUBTREE = IT(compute_subtree_last)(old);
+}
+
+static const struct rb_augment_callbacks IT(augment_callbacks) = {
+	IT(augment_propagate), IT(augment_copy), IT(augment_rotate)
+};
+
+/* Insert / remove interval nodes from the tree */
+
+ITSTATIC void IT(insert)(ITSTRUCT *node, struct rb_root *root)
+{
+	struct rb_node **link = &root->rb_node, *rb_parent = NULL;
+	ITTYPE start = ITSTART(node), last = ITLAST(node);
+	ITSTRUCT *parent;
+
+	while (*link) {
+		rb_parent = *link;
+		parent = rb_entry(rb_parent, ITSTRUCT, ITRB);
+		if (parent->ITSUBTREE < last)
+			parent->ITSUBTREE = last;
+		if (start < ITSTART(parent))
+			link = &parent->ITRB.rb_left;
+		else
+			link = &parent->ITRB.rb_right;
+	}
+
+	node->ITSUBTREE = last;
+	rb_link_node(&node->ITRB, rb_parent, link);
+	rb_insert_augmented(&node->ITRB, root, &IT(augment_callbacks));
+}
+
+ITSTATIC void IT(remove)(ITSTRUCT *node, struct rb_root *root)
+{
+	rb_erase_augmented(&node->ITRB, root, &IT(augment_callbacks));
+}
+
+/*
+ * Iterate over intervals intersecting [start;last]
+ *
+ * Note that a node's interval intersects [start;last] iff:
+ *   Cond1: ITSTART(node) <= last
+ * and
+ *   Cond2: start <= ITLAST(node)
+ */
+
+static ITSTRUCT *IT(subtree_search)(ITSTRUCT *node, ITTYPE start, ITTYPE last)
+{
+	while (true) {
+		/*
+		 * Loop invariant: start <= node->ITSUBTREE
+		 * (Cond2 is satisfied by one of the subtree nodes)
+		 */
+		if (node->ITRB.rb_left) {
+			ITSTRUCT *left = rb_entry(node->ITRB.rb_left,
+						  ITSTRUCT, ITRB);
+			if (start <= left->ITSUBTREE) {
+				/*
+				 * Some nodes in left subtree satisfy Cond2.
+				 * Iterate to find the leftmost such node N.
+				 * If it also satisfies Cond1, that's the match
+				 * we are looking for. Otherwise, there is no
+				 * matching interval as nodes to the right of N
+				 * can't satisfy Cond1 either.
+				 */
+				node = left;
+				continue;
+			}
+		}
+		if (ITSTART(node) <= last) {		/* Cond1 */
+			if (start <= ITLAST(node))	/* Cond2 */
+				return node;	/* node is leftmost match */
+			if (node->ITRB.rb_right) {
+				node = rb_entry(node->ITRB.rb_right,
+						ITSTRUCT, ITRB);
+				if (start <= node->ITSUBTREE)
+					continue;
+			}
+		}
+		return NULL;	/* No match */
+	}
+}
+
+ITSTATIC ITSTRUCT *IT(iter_first)(struct rb_root *root,
+				  ITTYPE start, ITTYPE last)
+{
+	ITSTRUCT *node;
+
+	if (!root->rb_node)
+		return NULL;
+	node = rb_entry(root->rb_node, ITSTRUCT, ITRB);
+	if (node->ITSUBTREE < start)
+		return NULL;
+	return IT(subtree_search)(node, start, last);
+}
+
+ITSTATIC ITSTRUCT *IT(iter_next)(ITSTRUCT *node, ITTYPE start, ITTYPE last)
+{
+	struct rb_node *rb = node->ITRB.rb_right, *prev;
+
+	while (true) {
+		/*
+		 * Loop invariants:
+		 *   Cond1: ITSTART(node) <= last
+		 *   rb == node->ITRB.rb_right
+		 *
+		 * First, search right subtree if suitable
+		 */
+		if (rb) {
+			ITSTRUCT *right = rb_entry(rb, ITSTRUCT, ITRB);
+			if (start <= right->ITSUBTREE)
+				return IT(subtree_search)(right, start, last);
+		}
+
+		/* Move up the tree until we come from a node's left child */
+		do {
+			rb = rb_parent(&node->ITRB);
+			if (!rb)
+				return NULL;
+			prev = &node->ITRB;
+			node = rb_entry(rb, ITSTRUCT, ITRB);
+			rb = node->ITRB.rb_right;
+		} while (prev == rb);
+
+		/* Check if the node intersects [start;last] */
+		if (last < ITSTART(node))		/* !Cond1 */
+			return NULL;
+		else if (start <= ITLAST(node))		/* Cond2 */
+			return node;
+	}
+}