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Diffstat (limited to 'kernel-lib/interval_tree_generic.h')
| -rw-r--r-- | kernel-lib/interval_tree_generic.h | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/kernel-lib/interval_tree_generic.h b/kernel-lib/interval_tree_generic.h new file mode 100644 index 00000000..e26c7322 --- /dev/null +++ b/kernel-lib/interval_tree_generic.h @@ -0,0 +1,193 @@ +/* + 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_generic.h +*/ + +#include <stdbool.h> + +#include "rbtree_augmented.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 endpoint of ITSTRUCT node n + * ITSTATIC: 'static' or empty + * ITPREFIX: prefix to use for the inline tree definitions + * + * Note - before using this, please consider if non-generic version + * (interval_tree.h) would work for you... + */ + +#define INTERVAL_TREE_DEFINE(ITSTRUCT, ITRB, ITTYPE, ITSUBTREE, \ + ITSTART, ITLAST, ITSTATIC, ITPREFIX) \ + \ +/* Callbacks for augmented rbtree insert and remove */ \ + \ +static inline ITTYPE ITPREFIX ## _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; \ +} \ + \ +RB_DECLARE_CALLBACKS(static, ITPREFIX ## _augment, ITSTRUCT, ITRB, \ + ITTYPE, ITSUBTREE, ITPREFIX ## _compute_subtree_last) \ + \ +/* Insert / remove interval nodes from the tree */ \ + \ +ITSTATIC void ITPREFIX ## _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, &ITPREFIX ## _augment); \ +} \ + \ +ITSTATIC void ITPREFIX ## _remove(ITSTRUCT *node, struct rb_root *root) \ +{ \ + rb_erase_augmented(&node->ITRB, root, &ITPREFIX ## _augment); \ +} \ + \ +/* \ + * 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 * \ +ITPREFIX ## _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 * \ +ITPREFIX ## _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 ITPREFIX ## _subtree_search(node, start, last); \ +} \ + \ +ITSTATIC ITSTRUCT * \ +ITPREFIX ## _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 ITPREFIX ## _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; \ + } \ +} |