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345 lines
9.3 KiB
345 lines
9.3 KiB
/* SPDX-License-Identifier: GPL-2.0-or-later */ |
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/* |
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Red Black Trees |
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(C) 1999 Andrea Arcangeli <[email protected]> |
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linux/include/linux/rbtree.h |
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To use rbtrees you'll have to implement your own insert and search cores. |
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This will avoid us to use callbacks and to drop drammatically performances. |
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I know it's not the cleaner way, but in C (not in C++) to get |
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performances and genericity... |
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See Documentation/core-api/rbtree.rst for documentation and samples. |
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*/ |
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#ifndef __TOOLS_LINUX_PERF_RBTREE_H |
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#define __TOOLS_LINUX_PERF_RBTREE_H |
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#include <linux/kernel.h> |
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#include <linux/stddef.h> |
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struct rb_node { |
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unsigned long __rb_parent_color; |
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struct rb_node *rb_right; |
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struct rb_node *rb_left; |
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} __attribute__((aligned(sizeof(long)))); |
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/* The alignment might seem pointless, but allegedly CRIS needs it */ |
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struct rb_root { |
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struct rb_node *rb_node; |
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}; |
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#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3)) |
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#define RB_ROOT (struct rb_root) { NULL, } |
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#define rb_entry(ptr, type, member) container_of(ptr, type, member) |
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#define RB_EMPTY_ROOT(root) (READ_ONCE((root)->rb_node) == NULL) |
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/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */ |
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#define RB_EMPTY_NODE(node) \ |
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((node)->__rb_parent_color == (unsigned long)(node)) |
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#define RB_CLEAR_NODE(node) \ |
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((node)->__rb_parent_color = (unsigned long)(node)) |
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extern void rb_insert_color(struct rb_node *, struct rb_root *); |
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extern void rb_erase(struct rb_node *, struct rb_root *); |
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/* Find logical next and previous nodes in a tree */ |
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extern struct rb_node *rb_next(const struct rb_node *); |
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extern struct rb_node *rb_prev(const struct rb_node *); |
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extern struct rb_node *rb_first(const struct rb_root *); |
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extern struct rb_node *rb_last(const struct rb_root *); |
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/* Postorder iteration - always visit the parent after its children */ |
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extern struct rb_node *rb_first_postorder(const struct rb_root *); |
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extern struct rb_node *rb_next_postorder(const struct rb_node *); |
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/* Fast replacement of a single node without remove/rebalance/add/rebalance */ |
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extern void rb_replace_node(struct rb_node *victim, struct rb_node *new, |
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struct rb_root *root); |
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static inline void rb_link_node(struct rb_node *node, struct rb_node *parent, |
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struct rb_node **rb_link) |
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{ |
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node->__rb_parent_color = (unsigned long)parent; |
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node->rb_left = node->rb_right = NULL; |
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*rb_link = node; |
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} |
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#define rb_entry_safe(ptr, type, member) \ |
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({ typeof(ptr) ____ptr = (ptr); \ |
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____ptr ? rb_entry(____ptr, type, member) : NULL; \ |
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}) |
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/** |
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* rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of |
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* given type allowing the backing memory of @pos to be invalidated |
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* |
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* @pos: the 'type *' to use as a loop cursor. |
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* @n: another 'type *' to use as temporary storage |
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* @root: 'rb_root *' of the rbtree. |
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* @field: the name of the rb_node field within 'type'. |
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* |
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* rbtree_postorder_for_each_entry_safe() provides a similar guarantee as |
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* list_for_each_entry_safe() and allows the iteration to continue independent |
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* of changes to @pos by the body of the loop. |
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* |
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* Note, however, that it cannot handle other modifications that re-order the |
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* rbtree it is iterating over. This includes calling rb_erase() on @pos, as |
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* rb_erase() may rebalance the tree, causing us to miss some nodes. |
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*/ |
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#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \ |
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for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \ |
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pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \ |
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typeof(*pos), field); 1; }); \ |
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pos = n) |
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static inline void rb_erase_init(struct rb_node *n, struct rb_root *root) |
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{ |
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rb_erase(n, root); |
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RB_CLEAR_NODE(n); |
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} |
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/* |
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* Leftmost-cached rbtrees. |
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* |
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* We do not cache the rightmost node based on footprint |
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* size vs number of potential users that could benefit |
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* from O(1) rb_last(). Just not worth it, users that want |
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* this feature can always implement the logic explicitly. |
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* Furthermore, users that want to cache both pointers may |
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* find it a bit asymmetric, but that's ok. |
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*/ |
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struct rb_root_cached { |
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struct rb_root rb_root; |
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struct rb_node *rb_leftmost; |
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}; |
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#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL } |
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/* Same as rb_first(), but O(1) */ |
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#define rb_first_cached(root) (root)->rb_leftmost |
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static inline void rb_insert_color_cached(struct rb_node *node, |
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struct rb_root_cached *root, |
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bool leftmost) |
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{ |
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if (leftmost) |
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root->rb_leftmost = node; |
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rb_insert_color(node, &root->rb_root); |
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} |
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static inline void rb_erase_cached(struct rb_node *node, |
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struct rb_root_cached *root) |
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{ |
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if (root->rb_leftmost == node) |
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root->rb_leftmost = rb_next(node); |
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rb_erase(node, &root->rb_root); |
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} |
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static inline void rb_replace_node_cached(struct rb_node *victim, |
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struct rb_node *new, |
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struct rb_root_cached *root) |
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{ |
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if (root->rb_leftmost == victim) |
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root->rb_leftmost = new; |
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rb_replace_node(victim, new, &root->rb_root); |
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} |
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/* |
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* The below helper functions use 2 operators with 3 different |
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* calling conventions. The operators are related like: |
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* |
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* comp(a->key,b) < 0 := less(a,b) |
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* comp(a->key,b) > 0 := less(b,a) |
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* comp(a->key,b) == 0 := !less(a,b) && !less(b,a) |
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* |
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* If these operators define a partial order on the elements we make no |
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* guarantee on which of the elements matching the key is found. See |
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* rb_find(). |
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* |
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* The reason for this is to allow the find() interface without requiring an |
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* on-stack dummy object, which might not be feasible due to object size. |
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*/ |
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/** |
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* rb_add_cached() - insert @node into the leftmost cached tree @tree |
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* @node: node to insert |
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* @tree: leftmost cached tree to insert @node into |
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* @less: operator defining the (partial) node order |
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*/ |
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static __always_inline void |
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rb_add_cached(struct rb_node *node, struct rb_root_cached *tree, |
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bool (*less)(struct rb_node *, const struct rb_node *)) |
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{ |
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struct rb_node **link = &tree->rb_root.rb_node; |
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struct rb_node *parent = NULL; |
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bool leftmost = true; |
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while (*link) { |
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parent = *link; |
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if (less(node, parent)) { |
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link = &parent->rb_left; |
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} else { |
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link = &parent->rb_right; |
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leftmost = false; |
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} |
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} |
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rb_link_node(node, parent, link); |
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rb_insert_color_cached(node, tree, leftmost); |
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} |
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/** |
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* rb_add() - insert @node into @tree |
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* @node: node to insert |
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* @tree: tree to insert @node into |
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* @less: operator defining the (partial) node order |
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*/ |
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static __always_inline void |
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rb_add(struct rb_node *node, struct rb_root *tree, |
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bool (*less)(struct rb_node *, const struct rb_node *)) |
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{ |
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struct rb_node **link = &tree->rb_node; |
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struct rb_node *parent = NULL; |
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while (*link) { |
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parent = *link; |
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if (less(node, parent)) |
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link = &parent->rb_left; |
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else |
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link = &parent->rb_right; |
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} |
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rb_link_node(node, parent, link); |
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rb_insert_color(node, tree); |
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} |
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/** |
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* rb_find_add() - find equivalent @node in @tree, or add @node |
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* @node: node to look-for / insert |
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* @tree: tree to search / modify |
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* @cmp: operator defining the node order |
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* |
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* Returns the rb_node matching @node, or NULL when no match is found and @node |
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* is inserted. |
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*/ |
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static __always_inline struct rb_node * |
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rb_find_add(struct rb_node *node, struct rb_root *tree, |
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int (*cmp)(struct rb_node *, const struct rb_node *)) |
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{ |
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struct rb_node **link = &tree->rb_node; |
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struct rb_node *parent = NULL; |
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int c; |
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while (*link) { |
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parent = *link; |
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c = cmp(node, parent); |
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if (c < 0) |
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link = &parent->rb_left; |
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else if (c > 0) |
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link = &parent->rb_right; |
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else |
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return parent; |
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} |
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rb_link_node(node, parent, link); |
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rb_insert_color(node, tree); |
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return NULL; |
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} |
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/** |
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* rb_find() - find @key in tree @tree |
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* @key: key to match |
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* @tree: tree to search |
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* @cmp: operator defining the node order |
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* |
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* Returns the rb_node matching @key or NULL. |
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*/ |
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static __always_inline struct rb_node * |
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rb_find(const void *key, const struct rb_root *tree, |
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int (*cmp)(const void *key, const struct rb_node *)) |
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{ |
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struct rb_node *node = tree->rb_node; |
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while (node) { |
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int c = cmp(key, node); |
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if (c < 0) |
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node = node->rb_left; |
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else if (c > 0) |
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node = node->rb_right; |
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else |
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return node; |
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} |
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return NULL; |
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} |
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/** |
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* rb_find_first() - find the first @key in @tree |
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* @key: key to match |
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* @tree: tree to search |
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* @cmp: operator defining node order |
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* |
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* Returns the leftmost node matching @key, or NULL. |
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*/ |
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static __always_inline struct rb_node * |
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rb_find_first(const void *key, const struct rb_root *tree, |
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int (*cmp)(const void *key, const struct rb_node *)) |
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{ |
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struct rb_node *node = tree->rb_node; |
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struct rb_node *match = NULL; |
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while (node) { |
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int c = cmp(key, node); |
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if (c <= 0) { |
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if (!c) |
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match = node; |
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node = node->rb_left; |
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} else if (c > 0) { |
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node = node->rb_right; |
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} |
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} |
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return match; |
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} |
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/** |
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* rb_next_match() - find the next @key in @tree |
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* @key: key to match |
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* @tree: tree to search |
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* @cmp: operator defining node order |
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* |
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* Returns the next node matching @key, or NULL. |
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*/ |
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static __always_inline struct rb_node * |
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rb_next_match(const void *key, struct rb_node *node, |
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int (*cmp)(const void *key, const struct rb_node *)) |
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{ |
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node = rb_next(node); |
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if (node && cmp(key, node)) |
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node = NULL; |
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return node; |
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} |
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/** |
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* rb_for_each() - iterates a subtree matching @key |
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* @node: iterator |
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* @key: key to match |
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* @tree: tree to search |
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* @cmp: operator defining node order |
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*/ |
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#define rb_for_each(node, key, tree, cmp) \ |
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for ((node) = rb_find_first((key), (tree), (cmp)); \ |
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(node); (node) = rb_next_match((key), (node), (cmp))) |
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#endif /* __TOOLS_LINUX_PERF_RBTREE_H */
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