xxhash.h

  1/*
  2 * xxHash - Extremely Fast Hash algorithm
  3 * Copyright (C) 2012-2016, Yann Collet.
  4 *
  5 * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
  6 *
  7 * Redistribution and use in source and binary forms, with or without
  8 * modification, are permitted provided that the following conditions are
  9 * met:
 10 *
 11 *   * Redistributions of source code must retain the above copyright
 12 *     notice, this list of conditions and the following disclaimer.
 13 *   * Redistributions in binary form must reproduce the above
 14 *     copyright notice, this list of conditions and the following disclaimer
 15 *     in the documentation and/or other materials provided with the
 16 *     distribution.
 17 *
 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 29 *
 30 * This program is free software; you can redistribute it and/or modify it under
 31 * the terms of the GNU General Public License version 2 as published by the
 32 * Free Software Foundation. This program is dual-licensed; you may select
 33 * either version 2 of the GNU General Public License ("GPL") or BSD license
 34 * ("BSD").
 35 *
 36 * You can contact the author at:
 37 * - xxHash homepage: https://cyan4973.github.io/xxHash/
 38 * - xxHash source repository: https://github.com/Cyan4973/xxHash
 39 */
 40
 41/*
 42 * Notice extracted from xxHash homepage:
 43 *
 44 * xxHash is an extremely fast Hash algorithm, running at RAM speed limits.
 45 * It also successfully passes all tests from the SMHasher suite.
 46 *
 47 * Comparison (single thread, Windows Seven 32 bits, using SMHasher on a Core 2
 48 * Duo @3GHz)
 49 *
 50 * Name            Speed       Q.Score   Author
 51 * xxHash          5.4 GB/s     10
 52 * CrapWow         3.2 GB/s      2       Andrew
 53 * MumurHash 3a    2.7 GB/s     10       Austin Appleby
 54 * SpookyHash      2.0 GB/s     10       Bob Jenkins
 55 * SBox            1.4 GB/s      9       Bret Mulvey
 56 * Lookup3         1.2 GB/s      9       Bob Jenkins
 57 * SuperFastHash   1.2 GB/s      1       Paul Hsieh
 58 * CityHash64      1.05 GB/s    10       Pike & Alakuijala
 59 * FNV             0.55 GB/s     5       Fowler, Noll, Vo
 60 * CRC32           0.43 GB/s     9
 61 * MD5-32          0.33 GB/s    10       Ronald L. Rivest
 62 * SHA1-32         0.28 GB/s    10
 63 *
 64 * Q.Score is a measure of quality of the hash function.
 65 * It depends on successfully passing SMHasher test set.
 66 * 10 is a perfect score.
 67 *
 68 * A 64-bits version, named xxh64 offers much better speed,
 69 * but for 64-bits applications only.
 70 * Name     Speed on 64 bits    Speed on 32 bits
 71 * xxh64       13.8 GB/s            1.9 GB/s
 72 * xxh32        6.8 GB/s            6.0 GB/s
 73 */
 74
 75#ifndef XXHASH_H
 76#define XXHASH_H
 77
 78#include <linux/types.h>
 79
 80/*-****************************
 81 * Simple Hash Functions
 82 *****************************/
 83
 84/**
 85 * xxh32() - calculate the 32-bit hash of the input with a given seed.
 86 *
 87 * @input:  The data to hash.
 88 * @length: The length of the data to hash.
 89 * @seed:   The seed can be used to alter the result predictably.
 90 *
 91 * Speed on Core 2 Duo @ 3 GHz (single thread, SMHasher benchmark) : 5.4 GB/s
 92 *
 93 * Return:  The 32-bit hash of the data.
 94 */
 95uint32_t xxh32(const void *input, size_t length, uint32_t seed);
 96
 97/**
 98 * xxh64() - calculate the 64-bit hash of the input with a given seed.
 99 *
100 * @input:  The data to hash.
101 * @length: The length of the data to hash.
102 * @seed:   The seed can be used to alter the result predictably.
103 *
104 * This function runs 2x faster on 64-bit systems, but slower on 32-bit systems.
105 *
106 * Return:  The 64-bit hash of the data.
107 */
108uint64_t xxh64(const void *input, size_t length, uint64_t seed);
109
110/**
111 * xxhash() - calculate wordsize hash of the input with a given seed
112 * @input:  The data to hash.
113 * @length: The length of the data to hash.
114 * @seed:   The seed can be used to alter the result predictably.
115 *
116 * If the hash does not need to be comparable between machines with
117 * different word sizes, this function will call whichever of xxh32()
118 * or xxh64() is faster.
119 *
120 * Return:  wordsize hash of the data.
121 */
122
123static inline unsigned long xxhash(const void *input, size_t length,
124				   uint64_t seed)
125{
126#if BITS_PER_LONG == 64
127       return xxh64(input, length, seed);
128#else
129       return xxh32(input, length, seed);
130#endif
131}
132
133/*-****************************
134 * Streaming Hash Functions
135 *****************************/
136
137/*
138 * These definitions are only meant to allow allocation of XXH state
139 * statically, on stack, or in a struct for example.
140 * Do not use members directly.
141 */
142
143/**
144 * struct xxh64_state - private xxh64 state, do not use members directly
145 */
146struct xxh64_state {
147	uint64_t total_len;
148	uint64_t v1;
149	uint64_t v2;
150	uint64_t v3;
151	uint64_t v4;
152	uint64_t mem64[4];
153	uint32_t memsize;
154};
155
156/**
157 * xxh64_reset() - reset the xxh64 state to start a new hashing operation
158 *
159 * @state: The xxh64 state to reset.
160 * @seed:  Initialize the hash state with this seed.
161 */
162void xxh64_reset(struct xxh64_state *state, uint64_t seed);
163
164/**
165 * xxh64_update() - hash the data given and update the xxh64 state
166 * @state:  The xxh64 state to update.
167 * @input:  The data to hash.
168 * @length: The length of the data to hash.
169 *
170 * After calling xxh64_reset() call xxh64_update() as many times as necessary.
171 *
172 * Return:  Zero on success, otherwise an error code.
173 */
174int xxh64_update(struct xxh64_state *state, const void *input, size_t length);
175
176/**
177 * xxh64_digest() - produce the current xxh64 hash
178 *
179 * @state: Produce the current xxh64 hash of this state.
180 *
181 * A hash value can be produced at any time. It is still possible to continue
182 * inserting input into the hash state after a call to xxh64_digest(), and
183 * generate new hashes later on, by calling xxh64_digest() again.
184 *
185 * Return: The xxh64 hash stored in the state.
186 */
187uint64_t xxh64_digest(const struct xxh64_state *state);
188
189#endif /* XXHASH_H */