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Commit | Line | Data |
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9dd228b5 HS |
1 | /* |
2 | Red Black Trees | |
3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> | |
4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> | |
5 | (C) 2012 Michel Lespinasse <walken@google.com> | |
6 | ||
7 | * SPDX-License-Identifier: GPL-2.0+ | |
8 | ||
9 | linux/include/linux/rbtree_augmented.h | |
10 | */ | |
11 | ||
12 | #ifndef _LINUX_RBTREE_AUGMENTED_H | |
13 | #define _LINUX_RBTREE_AUGMENTED_H | |
14 | ||
15 | #include <linux/compiler.h> | |
16 | #include <linux/rbtree.h> | |
17 | ||
18 | /* | |
19 | * Please note - only struct rb_augment_callbacks and the prototypes for | |
20 | * rb_insert_augmented() and rb_erase_augmented() are intended to be public. | |
21 | * The rest are implementation details you are not expected to depend on. | |
22 | * | |
23 | * See Documentation/rbtree.txt for documentation and samples. | |
24 | */ | |
25 | ||
26 | struct rb_augment_callbacks { | |
27 | void (*propagate)(struct rb_node *node, struct rb_node *stop); | |
28 | void (*copy)(struct rb_node *old, struct rb_node *new); | |
29 | void (*rotate)(struct rb_node *old, struct rb_node *new); | |
30 | }; | |
31 | ||
32 | extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, | |
33 | void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); | |
34 | static inline void | |
35 | rb_insert_augmented(struct rb_node *node, struct rb_root *root, | |
36 | const struct rb_augment_callbacks *augment) | |
37 | { | |
38 | __rb_insert_augmented(node, root, augment->rotate); | |
39 | } | |
40 | ||
41 | #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \ | |
42 | rbtype, rbaugmented, rbcompute) \ | |
43 | static inline void \ | |
44 | rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \ | |
45 | { \ | |
46 | while (rb != stop) { \ | |
47 | rbstruct *node = rb_entry(rb, rbstruct, rbfield); \ | |
48 | rbtype augmented = rbcompute(node); \ | |
49 | if (node->rbaugmented == augmented) \ | |
50 | break; \ | |
51 | node->rbaugmented = augmented; \ | |
52 | rb = rb_parent(&node->rbfield); \ | |
53 | } \ | |
54 | } \ | |
55 | static inline void \ | |
56 | rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ | |
57 | { \ | |
58 | rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ | |
59 | rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ | |
60 | new->rbaugmented = old->rbaugmented; \ | |
61 | } \ | |
62 | static void \ | |
63 | rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ | |
64 | { \ | |
65 | rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ | |
66 | rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ | |
67 | new->rbaugmented = old->rbaugmented; \ | |
68 | old->rbaugmented = rbcompute(old); \ | |
69 | } \ | |
70 | rbstatic const struct rb_augment_callbacks rbname = { \ | |
71 | rbname ## _propagate, rbname ## _copy, rbname ## _rotate \ | |
72 | }; | |
73 | ||
74 | ||
75 | #define RB_RED 0 | |
76 | #define RB_BLACK 1 | |
77 | ||
78 | #define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) | |
79 | ||
80 | #define __rb_color(pc) ((pc) & 1) | |
81 | #define __rb_is_black(pc) __rb_color(pc) | |
82 | #define __rb_is_red(pc) (!__rb_color(pc)) | |
83 | #define rb_color(rb) __rb_color((rb)->__rb_parent_color) | |
84 | #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) | |
85 | #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) | |
86 | ||
87 | static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) | |
88 | { | |
89 | rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; | |
90 | } | |
91 | ||
92 | static inline void rb_set_parent_color(struct rb_node *rb, | |
93 | struct rb_node *p, int color) | |
94 | { | |
95 | rb->__rb_parent_color = (unsigned long)p | color; | |
96 | } | |
97 | ||
98 | static inline void | |
99 | __rb_change_child(struct rb_node *old, struct rb_node *new, | |
100 | struct rb_node *parent, struct rb_root *root) | |
101 | { | |
102 | if (parent) { | |
103 | if (parent->rb_left == old) | |
104 | parent->rb_left = new; | |
105 | else | |
106 | parent->rb_right = new; | |
107 | } else | |
108 | root->rb_node = new; | |
109 | } | |
110 | ||
111 | extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, | |
112 | void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); | |
113 | ||
114 | static __always_inline struct rb_node * | |
115 | __rb_erase_augmented(struct rb_node *node, struct rb_root *root, | |
116 | const struct rb_augment_callbacks *augment) | |
117 | { | |
118 | struct rb_node *child = node->rb_right, *tmp = node->rb_left; | |
119 | struct rb_node *parent, *rebalance; | |
120 | unsigned long pc; | |
121 | ||
122 | if (!tmp) { | |
123 | /* | |
124 | * Case 1: node to erase has no more than 1 child (easy!) | |
125 | * | |
126 | * Note that if there is one child it must be red due to 5) | |
127 | * and node must be black due to 4). We adjust colors locally | |
128 | * so as to bypass __rb_erase_color() later on. | |
129 | */ | |
130 | pc = node->__rb_parent_color; | |
131 | parent = __rb_parent(pc); | |
132 | __rb_change_child(node, child, parent, root); | |
133 | if (child) { | |
134 | child->__rb_parent_color = pc; | |
135 | rebalance = NULL; | |
136 | } else | |
137 | rebalance = __rb_is_black(pc) ? parent : NULL; | |
138 | tmp = parent; | |
139 | } else if (!child) { | |
140 | /* Still case 1, but this time the child is node->rb_left */ | |
141 | tmp->__rb_parent_color = pc = node->__rb_parent_color; | |
142 | parent = __rb_parent(pc); | |
143 | __rb_change_child(node, tmp, parent, root); | |
144 | rebalance = NULL; | |
145 | tmp = parent; | |
146 | } else { | |
147 | struct rb_node *successor = child, *child2; | |
148 | tmp = child->rb_left; | |
149 | if (!tmp) { | |
150 | /* | |
151 | * Case 2: node's successor is its right child | |
152 | * | |
153 | * (n) (s) | |
154 | * / \ / \ | |
155 | * (x) (s) -> (x) (c) | |
156 | * \ | |
157 | * (c) | |
158 | */ | |
159 | parent = successor; | |
160 | child2 = successor->rb_right; | |
161 | augment->copy(node, successor); | |
162 | } else { | |
163 | /* | |
164 | * Case 3: node's successor is leftmost under | |
165 | * node's right child subtree | |
166 | * | |
167 | * (n) (s) | |
168 | * / \ / \ | |
169 | * (x) (y) -> (x) (y) | |
170 | * / / | |
171 | * (p) (p) | |
172 | * / / | |
173 | * (s) (c) | |
174 | * \ | |
175 | * (c) | |
176 | */ | |
177 | do { | |
178 | parent = successor; | |
179 | successor = tmp; | |
180 | tmp = tmp->rb_left; | |
181 | } while (tmp); | |
182 | parent->rb_left = child2 = successor->rb_right; | |
183 | successor->rb_right = child; | |
184 | rb_set_parent(child, successor); | |
185 | augment->copy(node, successor); | |
186 | augment->propagate(parent, successor); | |
187 | } | |
188 | ||
189 | successor->rb_left = tmp = node->rb_left; | |
190 | rb_set_parent(tmp, successor); | |
191 | ||
192 | pc = node->__rb_parent_color; | |
193 | tmp = __rb_parent(pc); | |
194 | __rb_change_child(node, successor, tmp, root); | |
195 | if (child2) { | |
196 | successor->__rb_parent_color = pc; | |
197 | rb_set_parent_color(child2, parent, RB_BLACK); | |
198 | rebalance = NULL; | |
199 | } else { | |
200 | unsigned long pc2 = successor->__rb_parent_color; | |
201 | successor->__rb_parent_color = pc; | |
202 | rebalance = __rb_is_black(pc2) ? parent : NULL; | |
203 | } | |
204 | tmp = successor; | |
205 | } | |
206 | ||
207 | augment->propagate(tmp, NULL); | |
208 | return rebalance; | |
209 | } | |
210 | ||
211 | static __always_inline void | |
212 | rb_erase_augmented(struct rb_node *node, struct rb_root *root, | |
213 | const struct rb_augment_callbacks *augment) | |
214 | { | |
215 | struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); | |
216 | if (rebalance) | |
217 | __rb_erase_color(rebalance, root, augment->rotate); | |
218 | } | |
219 | ||
220 | #endif /* _LINUX_RBTREE_AUGMENTED_H */ |