/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2010 iX Systems, Inc.
 * Copyright (c) 2010 Panasas, Inc.
 * Copyright (c) 2013-2018 Mellanox Technologies, Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice unmodified, this list of conditions, and the following
 *    disclaimer.
 * 2. 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 AUTHOR ``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 AUTHOR 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.
 */
#ifndef _LINUXKPI_LINUX_RADIX_TREE_H_
#define _LINUXKPI_LINUX_RADIX_TREE_H_

#include <linux/rcupdate.h>
#include <linux/types.h>

#define RADIX_TREE_MAP_SHIFT    6
#define RADIX_TREE_MAP_SIZE     (1UL << RADIX_TREE_MAP_SHIFT)
#define RADIX_TREE_MAP_MASK     (RADIX_TREE_MAP_SIZE - 1UL)
#define RADIX_TREE_MAX_HEIGHT \
        howmany(sizeof(long) * NBBY, RADIX_TREE_MAP_SHIFT)

#define RADIX_TREE_MAX_TAGS     3
#define RADIX_TREE_TAG_LONGS    RADIX_TREE_MAP_SIZE

#define RADIX_TREE_ENTRY_MASK 3UL
#define RADIX_TREE_EXCEPTIONAL_ENTRY 2UL
#define RADIX_TREE_EXCEPTIONAL_SHIFT 2

#define RADIX_TREE_ITER_TAG_MASK        0x0f
#define RADIX_TREE_ITER_TAGGED          0x10

struct radix_tree_node {
        void            *slots[RADIX_TREE_MAP_SIZE];
        unsigned long   tags[RADIX_TREE_MAX_TAGS][RADIX_TREE_TAG_LONGS];
        int             count;
};

struct radix_tree_root {
        struct radix_tree_node  *rnode;
        gfp_t                   gfp_mask;
        int                     height;
        /* Linux stores root tags inside `gfp_mask`. */
        unsigned long           tags[RADIX_TREE_MAX_TAGS];
};

struct radix_tree_iter {
        unsigned long index;
};

#define RADIX_TREE_INIT(mask)                                           \
            { .rnode = NULL, .gfp_mask = mask, .height = 0 };
#define INIT_RADIX_TREE(root, mask)                                     \
            { (root)->rnode = NULL; (root)->gfp_mask = mask; (root)->height = 0; }
#define RADIX_TREE(name, mask)                                          \
            struct radix_tree_root name = RADIX_TREE_INIT(mask)

#define radix_tree_for_each_slot(slot, root, iter, start)               \
        for ((iter)->index = (start);                                   \
             radix_tree_iter_find(root, iter, &(slot), 0);              \
             (iter)->index++)

#define radix_tree_for_each_slot_tagged(slot, root, iter, start, tag)   \
        for ((iter)->index = (start);                                   \
             radix_tree_iter_find(root, iter, &(slot),                  \
                 RADIX_TREE_ITER_TAGGED | tag);                         \
             (iter)->index++)

static inline void *
radix_tree_deref_slot(void **slot)
{
        return (*slot);
}

static inline int
radix_tree_exception(void *arg)
{
        return ((uintptr_t)arg & RADIX_TREE_ENTRY_MASK);
}

void    *radix_tree_lookup(const struct radix_tree_root *, unsigned long);
void    *radix_tree_delete(struct radix_tree_root *, unsigned long);
int     radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
int     radix_tree_store(struct radix_tree_root *, unsigned long, void **);
bool    radix_tree_iter_find(const struct radix_tree_root *, struct radix_tree_iter *, void ***, int);
void    radix_tree_iter_delete(struct radix_tree_root *, struct radix_tree_iter *, void **);
void    *radix_tree_tag_set(struct radix_tree_root *root, unsigned long index, unsigned int tag);
void    *radix_tree_tag_clear(struct radix_tree_root *root, unsigned long index, unsigned int tag);
int     radix_tree_tagged(const struct radix_tree_root *root, unsigned int tag);
unsigned int    radix_tree_gang_lookup(const struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items);
unsigned int    radix_tree_gang_lookup_tag(const struct radix_tree_root *root, void **results, unsigned long first_index, unsigned int max_items, unsigned int tag);

#endif  /* _LINUXKPI_LINUX_RADIX_TREE_H_ */