include/linux/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: http://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  */
  95 uint32_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  */
 108 uint64_t xxh64(const void *input, size_t length, uint64_t seed);
 109
 110 /*-****************************
 111  * Streaming Hash Functions
 112  *****************************/
 113
 114 /*
 115  * These definitions are only meant to allow allocation of XXH state
 116  * statically, on stack, or in a struct for example.
 117  * Do not use members directly.
 118  */
 119
 120 /**
 121  * struct xxh32_state - private xxh32 state, do not use members directly
 122  */
 123 struct xxh32_state {
 124         uint32_t total_len_32;
 125         uint32_t large_len;
 126         uint32_t v1;
 127         uint32_t v2;
 128         uint32_t v3;
 129         uint32_t v4;
 130         uint32_t mem32[4];
 131         uint32_t memsize;
 132 };
 133
 134 /**
 135  * struct xxh32_state - private xxh64 state, do not use members directly
 136  */
 137 struct xxh64_state {
 138         uint64_t total_len;
 139         uint64_t v1;
 140         uint64_t v2;
 141         uint64_t v3;
 142         uint64_t v4;
 143         uint64_t mem64[4];
 144         uint32_t memsize;
 145 };
 146
 147 /**
 148  * xxh32_reset() - reset the xxh32 state to start a new hashing operation
 149  *
 150  * @state: The xxh32 state to reset.
 151  * @seed:  Initialize the hash state with this seed.
 152  *
 153  * Call this function on any xxh32_state to prepare for a new hashing operation.
 154  */
 155 void xxh32_reset(struct xxh32_state *state, uint32_t seed);
 156
 157 /**
 158  * xxh32_update() - hash the data given and update the xxh32 state
 159  *
 160  * @state:  The xxh32 state to update.
 161  * @input:  The data to hash.
 162  * @length: The length of the data to hash.
 163  *
 164  * After calling xxh32_reset() call xxh32_update() as many times as necessary.
 165  *
 166  * Return:  Zero on success, otherwise an error code.
 167  */
 168 int xxh32_update(struct xxh32_state *state, const void *input, size_t length);
 169
 170 /**
 171  * xxh32_digest() - produce the current xxh32 hash
 172  *
 173  * @state: Produce the current xxh32 hash of this state.
 174  *
 175  * A hash value can be produced at any time. It is still possible to continue
 176  * inserting input into the hash state after a call to xxh32_digest(), and
 177  * generate new hashes later on, by calling xxh32_digest() again.
 178  *
 179  * Return: The xxh32 hash stored in the state.
 180  */
 181 uint32_t xxh32_digest(const struct xxh32_state *state);
 182
 183 /**
 184  * xxh64_reset() - reset the xxh64 state to start a new hashing operation
 185  *
 186  * @state: The xxh64 state to reset.
 187  * @seed:  Initialize the hash state with this seed.
 188  */
 189 void xxh64_reset(struct xxh64_state *state, uint64_t seed);
 190
 191 /**
 192  * xxh64_update() - hash the data given and update the xxh64 state
 193  * @state:  The xxh64 state to update.
 194  * @input:  The data to hash.
 195  * @length: The length of the data to hash.
 196  *
 197  * After calling xxh64_reset() call xxh64_update() as many times as necessary.
 198  *
 199  * Return:  Zero on success, otherwise an error code.
 200  */
 201 int xxh64_update(struct xxh64_state *state, const void *input, size_t length);
 202
 203 /**
 204  * xxh64_digest() - produce the current xxh64 hash
 205  *
 206  * @state: Produce the current xxh64 hash of this state.
 207  *
 208  * A hash value can be produced at any time. It is still possible to continue
 209  * inserting input into the hash state after a call to xxh64_digest(), and
 210  * generate new hashes later on, by calling xxh64_digest() again.
 211  *
 212  * Return: The xxh64 hash stored in the state.
 213  */
 214 uint64_t xxh64_digest(const struct xxh64_state *state);
 215
 216 /*-**************************
 217  * Utils
 218  ***************************/
 219
 220 /**
 221  * xxh32_copy_state() - copy the source state into the destination state
 222  *
 223  * @src: The source xxh32 state.
 224  * @dst: The destination xxh32 state.
 225  */
 226 void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src);
 227
 228 /**
 229  * xxh64_copy_state() - copy the source state into the destination state
 230  *
 231  * @src: The source xxh64 state.
 232  * @dst: The destination xxh64 state.
 233  */
 234 void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src);
 235
 236 #endif /* XXHASH_H */