rbtree.h

#ifndef	__RBTREE_H__
#define	__RBTREE_H__

struct rb_node
{
    unsigned long  rb_parent_color;
#define	RB_RED		0
#define	RB_BLACK	1
    struct rb_node *rb_right;
    struct rb_node *rb_left;
} __attribute__((aligned(sizeof(long))));

struct rb_root
{
    struct rb_node *rb_node;
};

#define rb_parent(r)    ((struct rb_node *)((r)->rb_parent_color & ~3))
#define rb_color(r)     ((r)->rb_parent_color & 1)
#define rb_is_red(r)    (!rb_color(r))
#define rb_is_black(r)  rb_color(r)
#define rb_set_red(r)   do { (r)->rb_parent_color &= ~1; } while (0)
#define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0)

static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
{
    rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
}

static inline void rb_set_color(struct rb_node *rb, int color)
{
    rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
}

#define RB_ROOT	(struct rb_root) { NULL, }
#define	rb_entry(ptr, type, member) container_of(ptr, type, member)

#define RB_EMPTY_ROOT(root)	((root)->rb_node == NULL)
#define RB_EMPTY_NODE(node)	(rb_parent(node) == node)
#define RB_CLEAR_NODE(node)	(rb_set_parent(node, node))

void rb_insert_color(struct rb_node *, struct rb_root *);
void rb_erase(struct rb_node *, struct rb_root *);

/* Find logical next and previous nodes in a tree */
struct rb_node *rb_next(const struct rb_node *);
struct rb_node *rb_prev(const struct rb_node *);
struct rb_node *rb_first(const struct rb_root *);
struct rb_node *rb_last(const struct rb_root *);

/* Fast replacement of a single node without remove/rebalance/add/rebalance */
void rb_replace_node(struct rb_node *victim, struct rb_node *new,
                          struct rb_root *root);

static inline void rb_link_node(struct rb_node *node, struct rb_node *parent,
                                struct rb_node **rb_link)
{
    node->rb_parent_color = (unsigned long)parent;
    node->rb_left = node->rb_right = NULL;

    *rb_link = node;
}

#endif