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367350319b
Change the left-leaning red-black (LLRB) trees into left-leaning threaded red-black trees. Instead of NULL pointers at leaf nodes, use the otherwise unused field as a pointer to the lexical predecessor (left) or successor (right). This allows fast previous/next interator operation without needing to keep track of the root of the tree at all times. The additional metadata that needs to be kept can be done for "free" simply by changing "bool red" into a flag field. Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
83 lines
3.0 KiB
C
83 lines
3.0 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 1996-2020 The NASM Authors - All Rights Reserved
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* See the file AUTHORS included with the NASM distribution for
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* the specific copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following
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* conditions are met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following
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* disclaimer in the documentation and/or other materials provided
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* with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* ----------------------------------------------------------------------- */
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#ifndef NASM_RBTREE_H
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#define NASM_RBTREE_H
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#include "compiler.h"
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/*
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* This structure should be embedded in a larger data structure;
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* the final output from rb_search() can then be converted back
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* to the larger data structure via container_of().
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*
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* An empty tree is simply represented by a NULL pointer.
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*/
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/* Note: the values of these flags is significant */
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enum rbtree_node_flags {
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RBTREE_NODE_BLACK = 1, /* Node color is black */
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RBTREE_NODE_PRED = 2, /* Left pointer is an uplink */
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RBTREE_NODE_SUCC = 4 /* Right pointer is an uplink */
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};
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struct rbtree {
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uint64_t key;
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struct rbtree_metadata {
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struct rbtree *left, *right;
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enum rbtree_node_flags flags;
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} m;
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};
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/*
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* Add a node to a tree. Returns the new root pointer.
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* The key value in the structure needs to be preinitialized;
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* the rest of the structure should be zero.
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*/
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struct rbtree *rb_insert(struct rbtree *, struct rbtree *);
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/*
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* Find a node in the tree corresponding to the key immediately
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* <= the passed-in key value.
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*/
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struct rbtree *rb_search(const struct rbtree *, uint64_t);
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/*
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* Return the immediately previous or next node in key order.
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* Returns NULL if this node is the end of the
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*/
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struct rbtree *rb_prev(const struct rbtree *);
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struct rbtree *rb_next(const struct rbtree *);
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#endif /* NASM_RBTREE_H */
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