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  */
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  * 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 
xxhash(const void * input,size_t length,uint64_t seed)123 static 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 xxh32_state - private xxh32 state, do not use members directly
145  */
146 struct xxh32_state {
147 	uint32_t total_len_32;
148 	uint32_t large_len;
149 	uint32_t v1;
150 	uint32_t v2;
151 	uint32_t v3;
152 	uint32_t v4;
153 	uint32_t mem32[4];
154 	uint32_t memsize;
155 };
156 
157 /**
158  * struct xxh32_state - private xxh64 state, do not use members directly
159  */
160 struct xxh64_state {
161 	uint64_t total_len;
162 	uint64_t v1;
163 	uint64_t v2;
164 	uint64_t v3;
165 	uint64_t v4;
166 	uint64_t mem64[4];
167 	uint32_t memsize;
168 };
169 
170 /**
171  * xxh32_reset() - reset the xxh32 state to start a new hashing operation
172  *
173  * @state: The xxh32 state to reset.
174  * @seed:  Initialize the hash state with this seed.
175  *
176  * Call this function on any xxh32_state to prepare for a new hashing operation.
177  */
178 void xxh32_reset(struct xxh32_state *state, uint32_t seed);
179 
180 /**
181  * xxh32_update() - hash the data given and update the xxh32 state
182  *
183  * @state:  The xxh32 state to update.
184  * @input:  The data to hash.
185  * @length: The length of the data to hash.
186  *
187  * After calling xxh32_reset() call xxh32_update() as many times as necessary.
188  *
189  * Return:  Zero on success, otherwise an error code.
190  */
191 int xxh32_update(struct xxh32_state *state, const void *input, size_t length);
192 
193 /**
194  * xxh32_digest() - produce the current xxh32 hash
195  *
196  * @state: Produce the current xxh32 hash of this state.
197  *
198  * A hash value can be produced at any time. It is still possible to continue
199  * inserting input into the hash state after a call to xxh32_digest(), and
200  * generate new hashes later on, by calling xxh32_digest() again.
201  *
202  * Return: The xxh32 hash stored in the state.
203  */
204 uint32_t xxh32_digest(const struct xxh32_state *state);
205 
206 /**
207  * xxh64_reset() - reset the xxh64 state to start a new hashing operation
208  *
209  * @state: The xxh64 state to reset.
210  * @seed:  Initialize the hash state with this seed.
211  */
212 void xxh64_reset(struct xxh64_state *state, uint64_t seed);
213 
214 /**
215  * xxh64_update() - hash the data given and update the xxh64 state
216  * @state:  The xxh64 state to update.
217  * @input:  The data to hash.
218  * @length: The length of the data to hash.
219  *
220  * After calling xxh64_reset() call xxh64_update() as many times as necessary.
221  *
222  * Return:  Zero on success, otherwise an error code.
223  */
224 int xxh64_update(struct xxh64_state *state, const void *input, size_t length);
225 
226 /**
227  * xxh64_digest() - produce the current xxh64 hash
228  *
229  * @state: Produce the current xxh64 hash of this state.
230  *
231  * A hash value can be produced at any time. It is still possible to continue
232  * inserting input into the hash state after a call to xxh64_digest(), and
233  * generate new hashes later on, by calling xxh64_digest() again.
234  *
235  * Return: The xxh64 hash stored in the state.
236  */
237 uint64_t xxh64_digest(const struct xxh64_state *state);
238 
239 /*-**************************
240  * Utils
241  ***************************/
242 
243 /**
244  * xxh32_copy_state() - copy the source state into the destination state
245  *
246  * @src: The source xxh32 state.
247  * @dst: The destination xxh32 state.
248  */
249 void xxh32_copy_state(struct xxh32_state *dst, const struct xxh32_state *src);
250 
251 /**
252  * xxh64_copy_state() - copy the source state into the destination state
253  *
254  * @src: The source xxh64 state.
255  * @dst: The destination xxh64 state.
256  */
257 void xxh64_copy_state(struct xxh64_state *dst, const struct xxh64_state *src);
258 
259 #endif /* XXHASH_H */
260