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2 * Copyright (c) 2008, 2009, 2010, 2012, 2013, 2014, 2016 Nicira, Inc.
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at:
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
29 static inline uint32_t
30 hash_rot(uint32_t x
, int k
)
32 return (x
<< k
) | (x
>> (32 - k
));
35 uint32_t hash_bytes(const void *, size_t n_bytes
, uint32_t basis
);
36 /* The hash input must be a word larger than 128 bits. */
37 void hash_bytes128(const void *_
, size_t n_bytes
, uint32_t basis
,
40 static inline uint32_t hash_int(uint32_t x
, uint32_t basis
);
41 static inline uint32_t hash_2words(uint32_t, uint32_t);
42 static inline uint32_t hash_uint64(const uint64_t);
43 static inline uint32_t hash_uint64_basis(const uint64_t x
,
44 const uint32_t basis
);
45 uint32_t hash_3words(uint32_t, uint32_t, uint32_t);
47 static inline uint32_t hash_boolean(bool x
, uint32_t basis
);
48 uint32_t hash_double(double, uint32_t basis
);
50 static inline uint32_t hash_pointer(const void *, uint32_t basis
);
51 static inline uint32_t hash_string(const char *, uint32_t basis
);
53 /* Murmurhash by Austin Appleby,
54 * from https://github.com/aappleby/smhasher/blob/master/src/MurmurHash3.cpp
56 * The upstream license there says:
58 * MurmurHash3 was written by Austin Appleby, and is placed in the public
59 * domain. The author hereby disclaims copyright to this source code.
61 * See hash_words() for sample usage. */
63 static inline uint32_t mhash_add__(uint32_t hash
, uint32_t data
)
65 /* zero-valued 'data' will not change the 'hash' value */
71 data
= hash_rot(data
, 15);
76 static inline uint32_t mhash_add(uint32_t hash
, uint32_t data
)
78 hash
= mhash_add__(hash
, data
);
79 hash
= hash_rot(hash
, 13);
80 return hash
* 5 + 0xe6546b64;
83 static inline uint32_t mhash_finish(uint32_t hash
)
93 static inline uint32_t hash_add(uint32_t hash
, uint32_t data
);
94 static inline uint32_t hash_add64(uint32_t hash
, uint64_t data
);
96 static inline uint32_t hash_add_words(uint32_t, const uint32_t *, size_t);
97 static inline uint32_t hash_add_words64(uint32_t, const uint64_t *, size_t);
98 static inline uint32_t hash_add_bytes32(uint32_t, const uint32_t *, size_t);
99 static inline uint32_t hash_add_bytes64(uint32_t, const uint64_t *, size_t);
101 #if (defined(__ARM_FEATURE_CRC32) && defined(__aarch64__))
102 #include "hash-aarch64.h"
104 #elif !(defined(__SSE4_2__) && defined(__x86_64__))
105 /* Mhash-based implementation. */
107 static inline uint32_t hash_add(uint32_t hash
, uint32_t data
)
109 return mhash_add(hash
, data
);
112 static inline uint32_t hash_add64(uint32_t hash
, uint64_t data
)
114 return hash_add(hash_add(hash
, data
), data
>> 32);
117 static inline uint32_t hash_finish(uint32_t hash
, uint32_t final
)
119 return mhash_finish(hash
^ final
);
122 /* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'.
123 * 'p' must be properly aligned.
125 * This is inlined for the compiler to have access to the 'n_words', which
126 * in many cases is a constant. */
127 static inline uint32_t
128 hash_words_inline(const uint32_t *p
, size_t n_words
, uint32_t basis
)
130 return hash_finish(hash_add_words(basis
, p
, n_words
), n_words
* 4);
133 static inline uint32_t
134 hash_words64_inline(const uint64_t *p
, size_t n_words
, uint32_t basis
)
136 return hash_finish(hash_add_words64(basis
, p
, n_words
), n_words
* 8);
139 static inline uint32_t hash_pointer(const void *p
, uint32_t basis
)
141 /* Often pointers are hashed simply by casting to integer type, but that
142 * has pitfalls since the lower bits of a pointer are often all 0 for
143 * alignment reasons. It's hard to guess where the entropy really is, so
144 * we give up here and just use a high-quality hash function.
146 * The double cast suppresses a warning on 64-bit systems about casting to
147 * an integer to different size. That's OK in this case, since most of the
148 * entropy in the pointer is almost certainly in the lower 32 bits. */
149 return hash_int((uint32_t) (uintptr_t) p
, basis
);
152 static inline uint32_t hash_2words(uint32_t x
, uint32_t y
)
154 return hash_finish(hash_add(hash_add(x
, 0), y
), 8);
157 static inline uint32_t hash_uint64_basis(const uint64_t x
,
158 const uint32_t basis
)
160 return hash_finish(hash_add64(basis
, x
), 8);
163 static inline uint32_t hash_uint64(const uint64_t x
)
165 return hash_uint64_basis(x
, 0);
168 #else /* __SSE4_2__ && __x86_64__ */
169 #include <smmintrin.h>
171 static inline uint32_t hash_add(uint32_t hash
, uint32_t data
)
173 return _mm_crc32_u32(hash
, data
);
176 /* Add the halves of 'data' in the memory order. */
177 static inline uint32_t hash_add64(uint32_t hash
, uint64_t data
)
179 return _mm_crc32_u64(hash
, data
);
182 static inline uint32_t hash_finish(uint64_t hash
, uint64_t final
)
184 /* The finishing multiplier 0x805204f3 has been experimentally
185 * derived to pass the testsuite hash tests. */
186 hash
= _mm_crc32_u64(hash
, final
) * 0x805204f3;
187 return hash
^ (uint32_t)hash
>> 16; /* Increase entropy in LSBs. */
190 /* Returns the hash of the 'n' 32-bit words at 'p_', starting from 'basis'.
191 * We access 'p_' as a uint64_t pointer, which is fine for __SSE_4_2__.
193 * This is inlined for the compiler to have access to the 'n_words', which
194 * in many cases is a constant. */
195 static inline uint32_t
196 hash_words_inline(const uint32_t p_
[], size_t n_words
, uint32_t basis
)
198 const uint64_t *p
= (const void *)p_
;
199 uint64_t hash1
= basis
;
201 uint64_t hash3
= n_words
;
202 const uint32_t *endp
= (const uint32_t *)p
+ n_words
;
203 const uint64_t *limit
= p
+ n_words
/ 2 - 3;
206 hash1
= _mm_crc32_u64(hash1
, p
[0]);
207 hash2
= _mm_crc32_u64(hash2
, p
[1]);
208 hash3
= _mm_crc32_u64(hash3
, p
[2]);
211 switch (endp
- (const uint32_t *)p
) {
213 hash1
= _mm_crc32_u32(hash1
, *(const uint32_t *)&p
[0]);
216 hash1
= _mm_crc32_u64(hash1
, p
[0]);
219 hash1
= _mm_crc32_u64(hash1
, p
[0]);
220 hash2
= _mm_crc32_u32(hash2
, *(const uint32_t *)&p
[1]);
223 hash1
= _mm_crc32_u64(hash1
, p
[0]);
224 hash2
= _mm_crc32_u64(hash2
, p
[1]);
227 hash1
= _mm_crc32_u64(hash1
, p
[0]);
228 hash2
= _mm_crc32_u64(hash2
, p
[1]);
229 hash3
= _mm_crc32_u32(hash3
, *(const uint32_t *)&p
[2]);
232 return hash_finish(hash1
, hash2
<< 32 | hash3
);
235 /* A simpler version for 64-bit data.
236 * 'n_words' is the count of 64-bit words, basis is 64 bits. */
237 static inline uint32_t
238 hash_words64_inline(const uint64_t p
[], size_t n_words
, uint32_t basis
)
240 uint64_t hash1
= basis
;
242 uint64_t hash3
= n_words
;
243 const uint64_t *endp
= p
+ n_words
;
244 const uint64_t *limit
= endp
- 3;
247 hash1
= _mm_crc32_u64(hash1
, p
[0]);
248 hash2
= _mm_crc32_u64(hash2
, p
[1]);
249 hash3
= _mm_crc32_u64(hash3
, p
[2]);
254 hash1
= _mm_crc32_u64(hash1
, p
[0]);
257 hash1
= _mm_crc32_u64(hash1
, p
[0]);
258 hash2
= _mm_crc32_u64(hash2
, p
[1]);
261 return hash_finish(hash1
, hash2
<< 32 | hash3
);
264 static inline uint32_t hash_uint64_basis(const uint64_t x
,
265 const uint32_t basis
)
267 /* '23' chosen to mix bits enough for the test-hash to pass. */
268 return hash_finish(hash_add64(basis
, x
), 23);
271 static inline uint32_t hash_uint64(const uint64_t x
)
273 return hash_uint64_basis(x
, 0);
276 static inline uint32_t hash_2words(uint32_t x
, uint32_t y
)
278 return hash_uint64((uint64_t)y
<< 32 | x
);
281 static inline uint32_t hash_pointer(const void *p
, uint32_t basis
)
283 return hash_uint64_basis((uint64_t) (uintptr_t) p
, basis
);
287 uint32_t hash_words__(const uint32_t p
[], size_t n_words
, uint32_t basis
);
288 uint32_t hash_words64__(const uint64_t p
[], size_t n_words
, uint32_t basis
);
290 /* Inline the larger hash functions only when 'n_words' is known to be
291 * compile-time constant. */
293 static inline uint32_t
294 hash_words(const uint32_t p
[], size_t n_words
, uint32_t basis
)
296 if (__builtin_constant_p(n_words
)) {
297 return hash_words_inline(p
, n_words
, basis
);
299 return hash_words__(p
, n_words
, basis
);
303 static inline uint32_t
304 hash_words64(const uint64_t p
[], size_t n_words
, uint32_t basis
)
306 if (__builtin_constant_p(n_words
)) {
307 return hash_words64_inline(p
, n_words
, basis
);
309 return hash_words64__(p
, n_words
, basis
);
315 static inline uint32_t
316 hash_words(const uint32_t p
[], size_t n_words
, uint32_t basis
)
318 return hash_words__(p
, n_words
, basis
);
321 static inline uint32_t
322 hash_words64(const uint64_t p
[], size_t n_words
, uint32_t basis
)
324 return hash_words64__(p
, n_words
, basis
);
328 static inline uint32_t
329 hash_bytes32(const uint32_t p
[], size_t n_bytes
, uint32_t basis
)
331 return hash_words(p
, n_bytes
/ 4, basis
);
334 static inline uint32_t
335 hash_bytes64(const uint64_t p
[], size_t n_bytes
, uint32_t basis
)
337 return hash_words64(p
, n_bytes
/ 8, basis
);
340 static inline uint32_t hash_string(const char *s
, uint32_t basis
)
342 return hash_bytes(s
, strlen(s
), basis
);
345 static inline uint32_t hash_int(uint32_t x
, uint32_t basis
)
347 return hash_2words(x
, basis
);
350 /* An attempt at a useful 1-bit hash function. Has not been analyzed for
352 static inline uint32_t hash_boolean(bool x
, uint32_t basis
)
354 const uint32_t P0
= 0xc2b73583; /* This is hash_int(1, 0). */
355 const uint32_t P1
= 0xe90f1258; /* This is hash_int(2, 0). */
356 return (x
? P0
: P1
) ^ hash_rot(basis
, 1);
359 /* Helper functions for calling hash_add() for several 32- or 64-bit words in a
360 * buffer. These are not hash functions by themselves, since they need
361 * hash_finish() to be called, so if you are looking for a full hash function
362 * see hash_words(), etc. */
364 static inline uint32_t
365 hash_add_words(uint32_t hash
, const uint32_t *p
, size_t n_words
)
367 for (size_t i
= 0; i
< n_words
; i
++) {
368 hash
= hash_add(hash
, p
[i
]);
373 static inline uint32_t
374 hash_add_words64(uint32_t hash
, const uint64_t *p
, size_t n_words
)
376 for (size_t i
= 0; i
< n_words
; i
++) {
377 hash
= hash_add64(hash
, p
[i
]);
382 static inline uint32_t
383 hash_add_bytes32(uint32_t hash
, const uint32_t *p
, size_t n_bytes
)
385 return hash_add_words(hash
, p
, n_bytes
/ 4);
388 static inline uint32_t
389 hash_add_bytes64(uint32_t hash
, const uint64_t *p
, size_t n_bytes
)
391 return hash_add_words64(hash
, p
, n_bytes
/ 8);