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/* SPDX-License-Identifier: BSD-2-Clause */
/* Copyright 1996-2020 The NASM Authors - All Rights Reserved */
#ifndef NASM_RBTREE_H
#define NASM_RBTREE_H
#include "compiler.h"
/*
* This structure should be embedded in a larger data structure;
* the final output from rb_search() can then be converted back
* to the larger data structure via container_of().
*
* An empty tree is simply represented by a NULL pointer.
*/
/* Note: the values of these flags is significant */
enum rbtree_node_flags {
RBTREE_NODE_BLACK = 1, /* Node color is black */
RBTREE_NODE_PRED = 2, /* Left pointer is an uplink */
RBTREE_NODE_SUCC = 4 /* Right pointer is an uplink */
};
struct rbtree {
uint64_t key;
struct rbtree_metadata {
struct rbtree *left, *right;
enum rbtree_node_flags flags;
} m;
};
/*
* Add a node to a tree. Returns the new root pointer.
* The key value in the structure needs to be preinitialized;
* the rest of the structure should be zero.
*/
struct rbtree *rb_insert(struct rbtree *, struct rbtree *);
/*
* Find a node in the tree corresponding to the key immediately
* <= the passed-in key value.
*/
struct rbtree * pure_func rb_search(const struct rbtree *, uint64_t);
/*
* Find a node in the tree exactly matching the key value.
*/
struct rbtree * pure_func rb_search_exact(const struct rbtree *, uint64_t);
/*
* Return the immediately previous or next node in key order.
* Returns NULL if this node is the end of the tree.
* These operations are safe for complete (but not partial!)
* tree walk-with-destruction in key order.
*/
struct rbtree * pure_func rb_prev(const struct rbtree *);
struct rbtree * pure_func rb_next(const struct rbtree *);
/*
* Return the very first or very last node in key order.
*/
struct rbtree * pure_func rb_first(const struct rbtree *);
struct rbtree * pure_func rb_last(const struct rbtree *);
/*
* Left and right nodes, if real. These operations are
* safe for tree destruction, but not for splitting a tree.
*/
static inline struct rbtree *rb_left(const struct rbtree *rb)
{
return (rb->m.flags & RBTREE_NODE_PRED) ? NULL : rb->m.left;
}
static inline struct rbtree *rb_right(const struct rbtree *rb)
{
return (rb->m.flags & RBTREE_NODE_SUCC) ? NULL : rb->m.right;
}
#endif /* NASM_RBTREE_H */
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