From 5e0b8d508ed51004bd836384293be00950ee62c9 Mon Sep 17 00:00:00 2001 From: Pasha Date: Tue, 20 Feb 2024 18:49:50 +0000 Subject: init gnumach copy --- kern/rbtree_i.h | 186 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 186 insertions(+) create mode 100644 kern/rbtree_i.h (limited to 'kern/rbtree_i.h') diff --git a/kern/rbtree_i.h b/kern/rbtree_i.h new file mode 100644 index 0000000..69dfb9d --- /dev/null +++ b/kern/rbtree_i.h @@ -0,0 +1,186 @@ +/* + * Copyright (c) 2010, 2011 Richard Braun. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef _KERN_RBTREE_I_H +#define _KERN_RBTREE_I_H + +#include + +/* + * Red-black node structure. + * + * To reduce the number of branches and the instruction cache footprint, + * the left and right child pointers are stored in an array, and the symmetry + * of most tree operations is exploited by using left/right variables when + * referring to children. + * + * In addition, this implementation assumes that all nodes are 4-byte aligned, + * so that the least significant bit of the parent member can be used to store + * the color of the node. This is true for all modern 32 and 64 bits + * architectures, as long as the nodes aren't embedded in structures with + * special alignment constraints such as member packing. + */ +struct rbtree_node { + unsigned long parent; + struct rbtree_node *children[2]; +}; + +/* + * Red-black tree structure. + */ +struct rbtree { + struct rbtree_node *root; +}; + +/* + * Masks applied on the parent member of a node to obtain either the + * color or the parent address. + */ +#define RBTREE_COLOR_MASK 0x1UL +#define RBTREE_PARENT_MASK (~0x3UL) + +/* + * Node colors. + */ +#define RBTREE_COLOR_RED 0 +#define RBTREE_COLOR_BLACK 1 + +/* + * Masks applied on slots to obtain either the child index or the parent + * address. + */ +#define RBTREE_SLOT_INDEX_MASK 0x1UL +#define RBTREE_SLOT_PARENT_MASK (~RBTREE_SLOT_INDEX_MASK) + +/* + * Return true if the given pointer is suitably aligned. + */ +static inline int rbtree_check_alignment(const struct rbtree_node *node) +{ + return ((unsigned long)node & (~RBTREE_PARENT_MASK)) == 0; +} + +/* + * Return true if the given index is a valid child index. + */ +static inline int rbtree_check_index(int index) +{ + return index == (index & 1); +} + +/* + * Convert the result of a comparison into an index in the children array + * (0 or 1). + * + * This function is mostly used when looking up a node. + */ +static inline int rbtree_d2i(int diff) +{ + return !(diff <= 0); +} + +/* + * Return the parent of a node. + */ +static inline struct rbtree_node * rbtree_parent(const struct rbtree_node *node) +{ + return (struct rbtree_node *)(node->parent & RBTREE_PARENT_MASK); +} + +/* + * Translate an insertion point into a slot. + */ +static inline unsigned long rbtree_slot(struct rbtree_node *parent, int index) +{ + assert(rbtree_check_alignment(parent)); + assert(rbtree_check_index(index)); + return (unsigned long)parent | index; +} + +/* + * Extract the parent address from a slot. + */ +static inline struct rbtree_node * rbtree_slot_parent(unsigned long slot) +{ + return (struct rbtree_node *)(slot & RBTREE_SLOT_PARENT_MASK); +} + +/* + * Extract the index from a slot. + */ +static inline int rbtree_slot_index(unsigned long slot) +{ + return slot & RBTREE_SLOT_INDEX_MASK; +} + +/* + * Insert a node in a tree, rebalancing it if necessary. + * + * The index parameter is the index in the children array of the parent where + * the new node is to be inserted. It is ignored if the parent is null. + * + * This function is intended to be used by the rbtree_insert() macro only. + */ +void rbtree_insert_rebalance(struct rbtree *tree, struct rbtree_node *parent, + int index, struct rbtree_node *node); + +/* + * Return the previous or next node relative to a location in a tree. + * + * The parent and index parameters define the location, which can be empty. + * The direction parameter is either RBTREE_LEFT (to obtain the previous + * node) or RBTREE_RIGHT (to obtain the next one). + */ +struct rbtree_node * rbtree_nearest(struct rbtree_node *parent, int index, + int direction); + +/* + * Return the first or last node of a tree. + * + * The direction parameter is either RBTREE_LEFT (to obtain the first node) + * or RBTREE_RIGHT (to obtain the last one). + */ +struct rbtree_node * rbtree_firstlast(const struct rbtree *tree, int direction); + +/* + * Return the node next to, or previous to the given node. + * + * The direction parameter is either RBTREE_LEFT (to obtain the previous node) + * or RBTREE_RIGHT (to obtain the next one). + */ +struct rbtree_node * rbtree_walk(struct rbtree_node *node, int direction); + +/* + * Return the left-most deepest node of a tree, which is the starting point of + * the postorder traversal performed by rbtree_for_each_remove(). + */ +struct rbtree_node * rbtree_postwalk_deepest(const struct rbtree *tree); + +/* + * Unlink a node from its tree and return the next (right) node in postorder. + */ +struct rbtree_node * rbtree_postwalk_unlink(struct rbtree_node *node); + +#endif /* _KERN_RBTREE_I_H */ -- cgit v1.2.1