/*-
 * Copyright (c) 2019 Taylor R. Campbell
 * 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, 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 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 AUTHOR 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.
 */

#ifndef	CRADIX_H
#define	CRADIX_H

#ifdef _KERNEL
#include <sys/types.h>
#include <machine/limits.h>
#else
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#endif

#ifdef _LP64
#define	CRADIX_CHUNK_SIZE	5u
typedef uint32_t cradix_bitmap_t;
#else
#define	CRADIX_CHUNK_SIZE	4u
typedef uint16_t cradix_bitmap_t;
#endif

#define	CRADIX_MAX_FANOUT	(1u << CRADIX_CHUNK_SIZE)
#define	CRADIX_CHUNK_MASK	(CRADIX_MAX_FANOUT - 1)

/*
 * Chunk indices are stored in 8 bits in branch nodes, so there can be
 * up to 256 chunks per key.  For the smallest chunk size, 4 bits, 256
 * chunks is 1024 bits = 128 bytes.
 */
#define	CRADIX_MAX_KEYLEN	128u

struct cradix_ops;

struct cradix {
	const struct cradix_ops	*ops;
	uintptr_t		root;
};

/*
 * Should be treated as opaque; used only for alignment and
 * type-checking.
 */
struct cradix_node {
} __aligned(2);

/* Opaque; allocated via the allocator.  */
struct cradix_branch;

struct cradix_ops {
	unsigned	keylen;
	const void *	(*key)(const struct cradix *,
			    const struct cradix_node *);
	void *		(*alloc)(struct cradix *, size_t);
	void		(*free)(struct cradix *, void *, size_t);
	void		(*recycle)(struct cradix *, void *, size_t);
};

void	cradix_init(struct cradix *, const struct cradix_ops *);
void	cradix_destroy(struct cradix *);

bool	cradix_empty(const struct cradix *);

struct cradix_node *
	cradix_lookup(const struct cradix *, const void *);
struct cradix_node *
	cradix_min(const struct cradix *);
struct cradix_node *
	cradix_max(const struct cradix *);
struct cradix_node *
	cradix_min_prefix(const struct cradix *, const void *, size_t);
struct cradix_node *
	cradix_max_prefix(const struct cradix *, const void *, size_t);

struct cradix_insert {
	struct cradix_branch	*alloc[CRADIX_CHUNK_SIZE];
	struct cradix_branch	*recycle;
};

bool	cradix_insert_begin(struct cradix *, struct cradix_insert *);
void	cradix_insert_end(struct cradix *, struct cradix_insert *);
struct cradix_node *
	cradix_insert(struct cradix *, struct cradix_node *,
	    struct cradix_insert *);

struct cradix_delete {
	struct cradix_branch	*recycle;
};

void	cradix_delete_begin(struct cradix *, struct cradix_delete *);
void	cradix_delete_end(struct cradix *, struct cradix_delete *);
void	cradix_delete(struct cradix *, struct cradix_node *,
	    struct cradix_delete *);
struct cradix_node *
	cradix_delete_key(struct cradix *, const void *,
	    struct cradix_delete *);

struct cradix_iter {
	struct cradix			*cradix;
	cradix_bitmap_t			submask;
	const struct cradix_branch	**branchstack;
	uint8_t				*chunkstack;
	unsigned			depth;
	unsigned			maxdepth;
};

#define	CRADIX_ITER_STACKDEPTH(KEYLEN)					      \
	((CHAR_BIT*(KEYLEN) + CRADIX_CHUNK_SIZE - 1) / CRADIX_CHUNK_SIZE)

#define	CRADIX_ITER_STACKTYPE(KEYLEN)					      \
	struct {							      \
		const struct cradix_branch *				      \
			branchstack[CRADIX_ITER_STACKDEPTH(KEYLEN)];	      \
		uint8_t	chunkstack[CRADIX_ITER_STACKDEPTH(KEYLEN)];	      \
	}

#define	CRADIX_ITER_STACKSIZE(KEYLEN)	sizeof(CRADIX_ITER_STACKTYPE(KEYLEN))
#define	CRADIX_ITER_ALIGNED	__attribute__((__aligned__(sizeof(void *))))

#ifdef _LP64
__CTASSERT(CRADIX_ITER_STACKSIZE(CRADIX_MAX_KEYLEN) == 1848);
#else
__CTASSERT(CRADIX_ITER_STACKSIZE(CRADIX_MAX_KEYLEN) == 1280);
#endif

#define	CRADIX_ITER_STACK(NAME, KEYLEN)					      \
	CRADIX_ITER_STACKTYPE(KEYLEN) NAME[1]
/* Alternatively:
	char NAME[CRADIX_ITER_STACKSIZE(KEYLEN)] CRADIX_ITER_ALIGNED */

void	cradix_iter_init(struct cradix *, struct cradix_iter *, void *,
	    size_t);
void	cradix_iter_destroy(struct cradix *, struct cradix_iter *);
bool	cradix_iter_begin(struct cradix *, struct cradix_iter *);
void	cradix_iter_end(struct cradix *, struct cradix_iter *);

struct cradix_node *
	cradix_iter_min(struct cradix *, struct cradix_iter *);
struct cradix_node *
	cradix_iter_max(struct cradix *, struct cradix_iter *);
struct cradix_node *
	cradix_iter_min_prefix(struct cradix *, struct cradix_iter *,
	    const void *, size_t);
struct cradix_node *
	cradix_iter_max_prefix(struct cradix *, struct cradix_iter *,
	    const void *, size_t);

struct cradix_node *
	cradix_iter_next(struct cradix *, struct cradix_iter *);
struct cradix_node *
	cradix_iter_prev(struct cradix *, struct cradix_iter *);

void	cradix_dump(const struct cradix *);

#endif	/* CRADIX_H */