/*
 * vim:tw=76:ts=4:sts=4:sw=4:cindent:expandtab
 */

#ifndef _PRIO_TREE_H
#define _PRIO_TREE_H

#ifdef DEBUG
#  ifdef NDEBUG
#    undef NDEBUG
#  endif
#else
#  ifndef NDEBUG
#    define NDEBUG
#  endif
#endif

#include <assert.h>
#include <limits.h>
#include <stdint.h>

#include "list.h"
#include "rbtree.h"
#include "helper.h"

/*
 * K&R 2nd ed. A8.3 somewhat obliquely hints that initial sequences of struct
 * fields with identical types should end up at the same location. We'll use
 * this until we can scrap struct raw_prio_tree_node.
 *
 * Note: all this could be done more elegantly by using unnamed union/struct
 * fields. However, gcc 2.95.3 and apparently also gcc 3.0.4 don't support this
 * language extension.
 */

typedef unsigned long pgoff_t;

struct raw_prio_tree_node {
    struct prio_tree_node *left;
    struct prio_tree_node *right;
    struct prio_tree_node *parent;
};

struct prio_tree_node {
    struct prio_tree_node *left;
    struct prio_tree_node *right;
    struct prio_tree_node *parent;
    unsigned long start;
    unsigned long last;         /* last location _in_ interval */
};

struct prio_tree_root {
    struct prio_tree_node *prio_tree_node;
    unsigned short index_bits;
    unsigned short raw;
    /*
     * 0: nodes are of type struct prio_tree_node
     * 1: nodes are of type raw_prio_tree_node
     */
};

struct prio_tree_iter {
    struct prio_tree_node *cur;
    unsigned long mask;
    unsigned long value;
    int size_level;

    struct prio_tree_root *root;
    pgoff_t r_index;
    pgoff_t h_index;
};

struct vm_area_struct {
    /* linked list of VM areas per task, sorted by address */
    struct vm_area_struct *vm_next;
    struct rb_node vm_rb;
    pgoff_t vm_pgoff;           /* Offset (within vm_file) in PAGE_SIZE
                                   units, *not* PAGE_CACHE_SIZE */
    pgoff_t vm_start;           /* Our start address within vm_mm. */
    pgoff_t vm_end;             /* The first byte after our end address */
    unsigned long vm_flags;     /* Flags, listed below. */
    union {
        struct {
            struct list_head list;
            void *parent;       /* aligns with prio_tree_node parent */
            struct vm_area_struct *head;
        } vm_set;
        struct raw_prio_tree_node prio_tree_node;
    } shared;
};

static inline void prio_tree_iter_init(struct prio_tree_iter *iter,
                                       struct prio_tree_root *root,
                                       pgoff_t r_index, pgoff_t h_index)
{
    iter->root = root;
    iter->r_index = r_index;
    iter->h_index = h_index;
    iter->cur = NULL;
}

#define __INIT_PRIO_TREE_ROOT(ptr, _raw)	\
do {					\
	(ptr)->prio_tree_node = NULL;	\
	(ptr)->index_bits = 1;		\
	(ptr)->raw = (_raw);		\
} while (0)

#define INIT_PRIO_TREE_ROOT(ptr)	__INIT_PRIO_TREE_ROOT(ptr, 0)
#define INIT_RAW_PRIO_TREE_ROOT(ptr)	__INIT_PRIO_TREE_ROOT(ptr, 1)

#define INIT_PRIO_TREE_NODE(ptr)				\
do {								\
	(ptr)->left = (ptr)->right = (ptr)->parent = (ptr);	\
} while (0)

#define INIT_PRIO_TREE_ITER(ptr)	\
do {					\
	(ptr)->cur = NULL;		\
	(ptr)->mask = 0UL;		\
	(ptr)->value = 0UL;		\
	(ptr)->size_level = 0;		\
} while (0)

#define prio_tree_entry(ptr, type, member) \
       ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

static inline int prio_tree_empty(const struct prio_tree_root *root)
{
    return root->prio_tree_node == NULL;
}

static inline int prio_tree_root(const struct prio_tree_node *node)
{
    return node->parent == node;
}

static inline int prio_tree_left_empty(const struct prio_tree_node *node)
{
    return node->left == node;
}

static inline int prio_tree_right_empty(const struct prio_tree_node *node)
{
    return node->right == node;
}


struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
                                         struct prio_tree_node *old,
                                         struct prio_tree_node *node);
struct prio_tree_node *prio_tree_insert(struct prio_tree_root *root,
                                        struct prio_tree_node *node);
void prio_tree_remove(struct prio_tree_root *root,
                      struct prio_tree_node *node);
struct prio_tree_node *prio_tree_next(struct prio_tree_iter *iter);

#define raw_prio_tree_replace(root, old, node) \
	prio_tree_replace(root, (struct prio_tree_node *) (old), \
	    (struct prio_tree_node *) (node))
#define raw_prio_tree_insert(root, node) \
	prio_tree_insert(root, (struct prio_tree_node *) (node))
#define raw_prio_tree_remove(root, node) \
	prio_tree_remove(root, (struct prio_tree_node *) (node))

#endif                          /* _PRIO_TREE_H */