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2 * Copyright (c) 2008, 2009, 2010, 2012, 2013, 2014 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 http://code.google.com/p/smhasher/source/browse/trunk/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
)
66 data
= hash_rot(data
, 15);
71 static inline uint32_t mhash_add(uint32_t hash
, uint32_t data
)
73 hash
= mhash_add__(hash
, data
);
74 hash
= hash_rot(hash
, 13);
75 return hash
* 5 + 0xe6546b64;
78 static inline uint32_t mhash_finish(uint32_t hash
)
88 #if !(defined(__SSE4_2__) && defined(__x86_64__))
89 /* Mhash-based implementation. */
91 static inline uint32_t hash_add(uint32_t hash
, uint32_t data
)
93 return mhash_add(hash
, data
);
96 static inline uint32_t hash_add64(uint32_t hash
, uint64_t data
)
98 return hash_add(hash_add(hash
, data
), data
>> 32);
101 static inline uint32_t hash_finish(uint32_t hash
, uint32_t final
)
103 return mhash_finish(hash
^ final
);
106 /* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'.
107 * 'p' must be properly aligned.
109 * This is inlined for the compiler to have access to the 'n_words', which
110 * in many cases is a constant. */
111 static inline uint32_t
112 hash_words_inline(const uint32_t p
[], size_t n_words
, uint32_t basis
)
118 for (i
= 0; i
< n_words
; i
++) {
119 hash
= hash_add(hash
, p
[i
]);
121 return hash_finish(hash
, n_words
* 4);
124 static inline uint32_t
125 hash_words64_inline(const uint64_t p
[], size_t n_words
, uint32_t basis
)
131 for (i
= 0; i
< n_words
; i
++) {
132 hash
= hash_add64(hash
, p
[i
]);
134 return hash_finish(hash
, n_words
* 8);
137 static inline uint32_t hash_pointer(const void *p
, uint32_t basis
)
139 /* Often pointers are hashed simply by casting to integer type, but that
140 * has pitfalls since the lower bits of a pointer are often all 0 for
141 * alignment reasons. It's hard to guess where the entropy really is, so
142 * we give up here and just use a high-quality hash function.
144 * The double cast suppresses a warning on 64-bit systems about casting to
145 * an integer to different size. That's OK in this case, since most of the
146 * entropy in the pointer is almost certainly in the lower 32 bits. */
147 return hash_int((uint32_t) (uintptr_t) p
, basis
);
150 static inline uint32_t hash_2words(uint32_t x
, uint32_t y
)
152 return hash_finish(hash_add(hash_add(x
, 0), y
), 8);
155 static inline uint32_t hash_uint64_basis(const uint64_t x
,
156 const uint32_t basis
)
158 return hash_finish(hash_add64(basis
, x
), 8);
161 static inline uint32_t hash_uint64(const uint64_t x
)
163 return hash_uint64_basis(x
, 0);
166 #else /* __SSE4_2__ && __x86_64__ */
167 #include <smmintrin.h>
169 static inline uint32_t hash_add(uint32_t hash
, uint32_t data
)
171 return _mm_crc32_u32(hash
, data
);
174 /* Add the halves of 'data' in the memory order. */
175 static inline uint32_t hash_add64(uint32_t hash
, uint64_t data
)
177 return _mm_crc32_u64(hash
, data
);
180 static inline uint32_t hash_finish(uint64_t hash
, uint64_t final
)
182 /* The finishing multiplier 0x805204f3 has been experimentally
183 * derived to pass the testsuite hash tests. */
184 hash
= _mm_crc32_u64(hash
, final
) * 0x805204f3;
185 return hash
^ (uint32_t)hash
>> 16; /* Increase entropy in LSBs. */
188 /* Returns the hash of the 'n' 32-bit words at 'p_', starting from 'basis'.
189 * We access 'p_' as a uint64_t pointer, which is fine for __SSE_4_2__.
191 * This is inlined for the compiler to have access to the 'n_words', which
192 * in many cases is a constant. */
193 static inline uint32_t
194 hash_words_inline(const uint32_t p_
[], size_t n_words
, uint32_t basis
)
196 const uint64_t *p
= (const void *)p_
;
197 uint64_t hash1
= basis
;
199 uint64_t hash3
= n_words
;
200 const uint32_t *endp
= (const uint32_t *)p
+ n_words
;
201 const uint64_t *limit
= p
+ n_words
/ 2 - 3;
204 hash1
= _mm_crc32_u64(hash1
, p
[0]);
205 hash2
= _mm_crc32_u64(hash2
, p
[1]);
206 hash3
= _mm_crc32_u64(hash3
, p
[2]);
209 switch (endp
- (const uint32_t *)p
) {
211 hash1
= _mm_crc32_u32(hash1
, *(const uint32_t *)&p
[0]);
214 hash1
= _mm_crc32_u64(hash1
, p
[0]);
217 hash1
= _mm_crc32_u64(hash1
, p
[0]);
218 hash2
= _mm_crc32_u32(hash2
, *(const uint32_t *)&p
[1]);
221 hash1
= _mm_crc32_u64(hash1
, p
[0]);
222 hash2
= _mm_crc32_u64(hash2
, p
[1]);
225 hash1
= _mm_crc32_u64(hash1
, p
[0]);
226 hash2
= _mm_crc32_u64(hash2
, p
[1]);
227 hash3
= _mm_crc32_u32(hash3
, *(const uint32_t *)&p
[2]);
230 return hash_finish(hash1
, hash2
<< 32 | hash3
);
233 /* A simpler version for 64-bit data.
234 * 'n_words' is the count of 64-bit words, basis is 64 bits. */
235 static inline uint32_t
236 hash_words64_inline(const uint64_t p
[], size_t n_words
, uint32_t basis
)
238 uint64_t hash1
= basis
;
240 uint64_t hash3
= n_words
;
241 const uint64_t *endp
= p
+ n_words
;
242 const uint64_t *limit
= endp
- 3;
245 hash1
= _mm_crc32_u64(hash1
, p
[0]);
246 hash2
= _mm_crc32_u64(hash2
, p
[1]);
247 hash3
= _mm_crc32_u64(hash3
, p
[2]);
252 hash1
= _mm_crc32_u64(hash1
, p
[0]);
255 hash1
= _mm_crc32_u64(hash1
, p
[0]);
256 hash2
= _mm_crc32_u64(hash2
, p
[1]);
259 return hash_finish(hash1
, hash2
<< 32 | hash3
);
262 static inline uint32_t hash_uint64_basis(const uint64_t x
,
263 const uint32_t basis
)
265 /* '23' chosen to mix bits enough for the test-hash to pass. */
266 return hash_finish(hash_add64(basis
, x
), 23);
269 static inline uint32_t hash_uint64(const uint64_t x
)
271 return hash_uint64_basis(x
, 0);
274 static inline uint32_t hash_2words(uint32_t x
, uint32_t y
)
276 return hash_uint64((uint64_t)y
<< 32 | x
);
279 static inline uint32_t hash_pointer(const void *p
, uint32_t basis
)
281 return hash_uint64_basis((uint64_t) (uintptr_t) p
, basis
);
285 uint32_t hash_words__(const uint32_t p
[], size_t n_words
, uint32_t basis
);
286 uint32_t hash_words64__(const uint64_t p
[], size_t n_words
, uint32_t basis
);
288 /* Inline the larger hash functions only when 'n_words' is known to be
289 * compile-time constant. */
291 static inline uint32_t
292 hash_words(const uint32_t p
[], size_t n_words
, uint32_t basis
)
294 if (__builtin_constant_p(n_words
)) {
295 return hash_words_inline(p
, n_words
, basis
);
297 return hash_words__(p
, n_words
, basis
);
301 static inline uint32_t
302 hash_words64(const uint64_t p
[], size_t n_words
, uint32_t basis
)
304 if (__builtin_constant_p(n_words
)) {
305 return hash_words64_inline(p
, n_words
, basis
);
307 return hash_words64__(p
, n_words
, basis
);
313 static inline uint32_t
314 hash_words(const uint32_t p
[], size_t n_words
, uint32_t basis
)
316 return hash_words__(p
, n_words
, basis
);
319 static inline uint32_t
320 hash_words64(const uint64_t p
[], size_t n_words
, uint32_t basis
)
322 return hash_words64__(p
, n_words
, basis
);
326 static inline uint32_t hash_string(const char *s
, uint32_t basis
)
328 return hash_bytes(s
, strlen(s
), basis
);
331 static inline uint32_t hash_int(uint32_t x
, uint32_t basis
)
333 return hash_2words(x
, basis
);
336 /* An attempt at a useful 1-bit hash function. Has not been analyzed for
338 static inline uint32_t hash_boolean(bool x
, uint32_t basis
)
340 const uint32_t P0
= 0xc2b73583; /* This is hash_int(1, 0). */
341 const uint32_t P1
= 0xe90f1258; /* This is hash_int(2, 0). */
342 return (x
? P0
: P1
) ^ hash_rot(basis
, 1);