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9e6747ccac
Add copyright headers to the *.c/*.h files in the main directory. For files where I'm sure enough that we have all the approvals, I have given them the 2-BSD license, the others have been given the "LGPL for now" license header. Most of them can probably be changed after auditing. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
120 lines
3.4 KiB
C
120 lines
3.4 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 1996-2009 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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/*
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* rbtree.c
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*
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* Simple implementation of a left-leaning red-black tree with 64-bit
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* integer keys. The search operation will return the highest node <=
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* the key; only search and insert are supported, but additional
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* standard llrbtree operations can be coded up at will.
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*
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* See http://www.cs.princeton.edu/~rs/talks/LLRB/RedBlack.pdf for
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* information about left-leaning red-black trees.
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*/
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#include "rbtree.h"
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struct rbtree *rb_search(struct rbtree *tree, uint64_t key)
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{
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struct rbtree *best = NULL;
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while (tree) {
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if (tree->key == key)
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return tree;
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else if (tree->key > key)
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tree = tree->left;
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else {
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best = tree;
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tree = tree->right;
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}
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}
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return best;
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}
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static bool is_red(struct rbtree *h)
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{
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return h && h->red;
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}
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static struct rbtree *rotate_left(struct rbtree *h)
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{
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struct rbtree *x = h->right;
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h->right = x->left;
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x->left = h;
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x->red = x->left->red;
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x->left->red = true;
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return x;
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}
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static struct rbtree *rotate_right(struct rbtree *h)
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{
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struct rbtree *x = h->left;
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h->left = x->right;
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x->right = h;
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x->red = x->right->red;
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x->right->red = true;
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return x;
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}
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static void color_flip(struct rbtree *h)
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{
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h->red = !h->red;
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h->left->red = !h->left->red;
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h->right->red = !h->right->red;
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}
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struct rbtree *rb_insert(struct rbtree *tree, struct rbtree *node)
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{
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if (!tree) {
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node->red = true;
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return node;
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}
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if (is_red(tree->left) && is_red(tree->right))
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color_flip(tree);
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if (node->key < tree->key)
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tree->left = rb_insert(tree->left, node);
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else
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tree->right = rb_insert(tree->right, node);
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if (is_red(tree->right))
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tree = rotate_left(tree);
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if (is_red(tree->left) && is_red(tree->left->left))
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tree = rotate_right(tree);
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return tree;
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}
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