diff nasmbuild/nasm-2.13rc9/nasmlib/rbtree.c @ 10554:587a0a262d22

<moonythedwarf> ` cd nasmbuild; tar -xf nasm.tar.gz
author HackBot
date Thu, 30 Mar 2017 20:58:41 +0000
parents
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nasmbuild/nasm-2.13rc9/nasmlib/rbtree.c	Thu Mar 30 20:58:41 2017 +0000
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+/* ----------------------------------------------------------------------- *
+ *   
+ *   Copyright 1996-2009 The NASM Authors - All Rights Reserved
+ *   See the file AUTHORS included with the NASM distribution for
+ *   the specific copyright holders.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following
+ *   conditions are met:
+ *
+ *   * Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *   * 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 COPYRIGHT HOLDERS AND
+ *     CONTRIBUTORS "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 COPYRIGHT OWNER OR
+ *     CONTRIBUTORS 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.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * rbtree.c
+ *
+ * Simple implementation of a left-leaning red-black tree with 64-bit
+ * integer keys.  The search operation will return the highest node <=
+ * the key; only search and insert are supported, but additional
+ * standard llrbtree operations can be coded up at will.
+ *
+ * See http://www.cs.princeton.edu/~rs/talks/LLRB/RedBlack.pdf for
+ * information about left-leaning red-black trees.
+ */
+
+#include "rbtree.h"
+
+struct rbtree *rb_search(struct rbtree *tree, uint64_t key)
+{
+    struct rbtree *best = NULL;
+
+    while (tree) {
+	if (tree->key == key)
+	    return tree;
+	else if (tree->key > key)
+	    tree = tree->left;
+	else {
+	    best = tree;
+	    tree = tree->right;
+	}
+    }
+    return best;
+}
+
+static bool is_red(struct rbtree *h)
+{
+    return h && h->red;
+}
+
+static struct rbtree *rotate_left(struct rbtree *h)
+{
+    struct rbtree *x = h->right;
+    h->right = x->left;
+    x->left = h;
+    x->red = x->left->red;
+    x->left->red = true;
+    return x;
+}
+
+static struct rbtree *rotate_right(struct rbtree *h)
+{
+    struct rbtree *x = h->left;
+    h->left = x->right;
+    x->right = h;
+    x->red = x->right->red;
+    x->right->red = true;
+    return x;
+}
+
+static void color_flip(struct rbtree *h)
+{
+    h->red = !h->red;
+    h->left->red = !h->left->red;
+    h->right->red = !h->right->red;
+}
+
+struct rbtree *rb_insert(struct rbtree *tree, struct rbtree *node)
+{
+    if (!tree) {
+	node->red = true;
+	return node;
+    }
+
+    if (is_red(tree->left) && is_red(tree->right))
+	color_flip(tree);
+
+    if (node->key < tree->key)
+	tree->left = rb_insert(tree->left, node);
+    else
+	tree->right = rb_insert(tree->right, node);
+
+    if (is_red(tree->right))
+	tree = rotate_left(tree);
+
+    if (is_red(tree->left) && is_red(tree->left->left))
+	tree = rotate_right(tree);
+
+    return tree;
+}