linux/include/linux/jhash.h

#ifndef _LINUX_JHASH_H
#define _LINUX_JHASH_H

/* jhash.h: Jenkins hash support.
 *
 * Copyright (C) 2006. Bob Jenkins ([email protected])
 *
 * https://burtleburtle.net/bob/hash/
 *
 * These are the credits from Bob's sources:
 *
 * lookup3.c, by Bob Jenkins, May 2006, Public Domain.
 *
 * These are functions for producing 32-bit hashes for hash table lookup.
 * hashword(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
 * are externally useful functions.  Routines to test the hash are included
 * if SELF_TEST is defined.  You can use this free for any purpose.  It's in
 * the public domain.  It has no warranty.
 *
 * Copyright (C) 2009-2010 Jozsef Kadlecsik ([email protected])
 *
 * I've modified Bob's hash to be useful in the Linux kernel, and
 * any bugs present are my fault.
 * Jozsef
 */
#include <linux/bitops.h>
#include <linux/unaligned/packed_struct.h>

/* Best hash sizes are of power of two */
#define jhash_size(n) …
/* Mask the hash value, i.e (value & jhash_mask(n)) instead of (value % n) */
#define jhash_mask(n) …

/* __jhash_mix - mix 3 32-bit values reversibly. */
#define __jhash_mix(a, b, c) …

/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
#define __jhash_final(a, b, c) …

/* An arbitrary initial parameter */
#define JHASH_INITVAL …

/* jhash - hash an arbitrary key
 * @k: sequence of bytes as key
 * @length: the length of the key
 * @initval: the previous hash, or an arbitrary value
 *
 * The generic version, hashes an arbitrary sequence of bytes.
 * No alignment or length assumptions are made about the input key.
 *
 * Returns the hash value of the key. The result depends on endianness.
 */
static inline u32 jhash(const void *key, u32 length, u32 initval)
{ … }

/* jhash2 - hash an array of u32's
 * @k: the key which must be an array of u32's
 * @length: the number of u32's in the key
 * @initval: the previous hash, or an arbitrary value
 *
 * Returns the hash value of the key.
 */
static inline u32 jhash2(const u32 *k, u32 length, u32 initval)
{ … }


/* __jhash_nwords - hash exactly 3, 2 or 1 word(s) */
static inline u32 __jhash_nwords(u32 a, u32 b, u32 c, u32 initval)
{ … }

static inline u32 jhash_3words(u32 a, u32 b, u32 c, u32 initval)
{ … }

static inline u32 jhash_2words(u32 a, u32 b, u32 initval)
{ … }

static inline u32 jhash_1word(u32 a, u32 initval)
{ … }

#endif /* _LINUX_JHASH_H */