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Diffstat (limited to 'include/linux/interval_tree_tmpl.h')
-rw-r--r-- | include/linux/interval_tree_tmpl.h | 215 |
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 index 0000000..c65deda --- /dev/null +++ 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; + } +} |