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064af421 | 1 | /* |
468cdd91 | 2 | * Copyright (c) 2008, 2009, 2010, 2012, 2013, 2014 Nicira, Inc. |
064af421 | 3 | * |
a14bc59f BP |
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: | |
064af421 | 7 | * |
a14bc59f BP |
8 | * http://www.apache.org/licenses/LICENSE-2.0 |
9 | * | |
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. | |
064af421 BP |
15 | */ |
16 | #ifndef HASH_H | |
17 | #define HASH_H 1 | |
18 | ||
8e542118 | 19 | #include <stdbool.h> |
064af421 BP |
20 | #include <stddef.h> |
21 | #include <stdint.h> | |
22 | #include <string.h> | |
cce1d8bd | 23 | #include "util.h" |
064af421 | 24 | |
43d1478b CB |
25 | #ifdef __cplusplus |
26 | extern "C" { | |
27 | #endif | |
28 | ||
d556327b BP |
29 | static inline uint32_t |
30 | hash_rot(uint32_t x, int k) | |
31 | { | |
32 | return (x << k) | (x >> (32 - k)); | |
33 | } | |
064af421 | 34 | |
c49d1dd1 | 35 | uint32_t hash_bytes(const void *, size_t n_bytes, uint32_t basis); |
2a638b8d | 36 | /* The hash input must be a word larger than 128 bits. */ |
468cdd91 JS |
37 | void hash_bytes128(const void *_, size_t n_bytes, uint32_t basis, |
38 | ovs_u128 *out); | |
c49d1dd1 BP |
39 | |
40 | static inline uint32_t hash_int(uint32_t x, uint32_t basis); | |
41 | static inline uint32_t hash_2words(uint32_t, uint32_t); | |
5df26bd0 GS |
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); | |
c49d1dd1 BP |
45 | uint32_t hash_3words(uint32_t, uint32_t, uint32_t); |
46 | ||
47 | static inline uint32_t hash_boolean(bool x, uint32_t basis); | |
48 | uint32_t hash_double(double, uint32_t basis); | |
49 | ||
50 | static inline uint32_t hash_pointer(const void *, uint32_t basis); | |
51 | static inline uint32_t hash_string(const char *, uint32_t basis); | |
52 | ||
53 | /* Murmurhash by Austin Appleby, | |
54 | * from http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp. | |
55 | * | |
56 | * The upstream license there says: | |
57 | * | |
58 | * // MurmurHash3 was written by Austin Appleby, and is placed in the public | |
59 | * // domain. The author hereby disclaims copyright to this source code. | |
60 | * | |
61 | * See hash_words() for sample usage. */ | |
62 | ||
63 | static inline uint32_t mhash_add__(uint32_t hash, uint32_t data) | |
d556327b | 64 | { |
c49d1dd1 BP |
65 | data *= 0xcc9e2d51; |
66 | data = hash_rot(data, 15); | |
67 | data *= 0x1b873593; | |
68 | return hash ^ data; | |
d556327b | 69 | } |
064af421 | 70 | |
c49d1dd1 | 71 | static inline uint32_t mhash_add(uint32_t hash, uint32_t data) |
d556327b | 72 | { |
c49d1dd1 BP |
73 | hash = mhash_add__(hash, data); |
74 | hash = hash_rot(hash, 13); | |
75 | return hash * 5 + 0xe6546b64; | |
d556327b | 76 | } |
064af421 | 77 | |
468cdd91 | 78 | static inline uint32_t mhash_finish(uint32_t hash) |
c49d1dd1 | 79 | { |
c49d1dd1 BP |
80 | hash ^= hash >> 16; |
81 | hash *= 0x85ebca6b; | |
82 | hash ^= hash >> 13; | |
83 | hash *= 0xc2b2ae35; | |
84 | hash ^= hash >> 16; | |
85 | return hash; | |
86 | } | |
064af421 | 87 | |
ff8eeabd | 88 | #if !(defined(__SSE4_2__) && defined(__x86_64__)) |
468cdd91 | 89 | /* Mhash-based implementation. */ |
ff8eeabd | 90 | |
33c6a1b9 JR |
91 | static inline uint32_t hash_add(uint32_t hash, uint32_t data) |
92 | { | |
93 | return mhash_add(hash, data); | |
94 | } | |
95 | ||
aae7c34f JR |
96 | static inline uint32_t hash_add64(uint32_t hash, uint64_t data) |
97 | { | |
98 | return hash_add(hash_add(hash, data), data >> 32); | |
99 | } | |
100 | ||
33c6a1b9 JR |
101 | static inline uint32_t hash_finish(uint32_t hash, uint32_t final) |
102 | { | |
468cdd91 | 103 | return mhash_finish(hash ^ final); |
33c6a1b9 JR |
104 | } |
105 | ||
ff8eeabd JR |
106 | /* Returns the hash of the 'n' 32-bit words at 'p', starting from 'basis'. |
107 | * 'p' must be properly aligned. | |
108 | * | |
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) | |
064af421 | 113 | { |
ff8eeabd JR |
114 | uint32_t hash; |
115 | size_t i; | |
064af421 | 116 | |
ff8eeabd JR |
117 | hash = basis; |
118 | for (i = 0; i < n_words; i++) { | |
119 | hash = hash_add(hash, p[i]); | |
120 | } | |
121 | return hash_finish(hash, n_words * 4); | |
064af421 BP |
122 | } |
123 | ||
ff8eeabd | 124 | static inline uint32_t |
4ad07ad7 | 125 | hash_words64_inline(const uint64_t p[], size_t n_words, uint32_t basis) |
8e542118 | 126 | { |
aae7c34f JR |
127 | uint32_t hash; |
128 | size_t i; | |
129 | ||
130 | hash = basis; | |
131 | for (i = 0; i < n_words; i++) { | |
132 | hash = hash_add64(hash, p[i]); | |
133 | } | |
134 | return hash_finish(hash, n_words * 8); | |
8e542118 BP |
135 | } |
136 | ||
00644675 BP |
137 | static inline uint32_t hash_pointer(const void *p, uint32_t basis) |
138 | { | |
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. | |
143 | * | |
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); | |
148 | } | |
149 | ||
c49d1dd1 | 150 | static inline uint32_t hash_2words(uint32_t x, uint32_t y) |
9879b94f | 151 | { |
33c6a1b9 | 152 | return hash_finish(hash_add(hash_add(x, 0), y), 8); |
9879b94f BP |
153 | } |
154 | ||
aae7c34f JR |
155 | static inline uint32_t hash_uint64_basis(const uint64_t x, |
156 | const uint32_t basis) | |
965607c8 | 157 | { |
aae7c34f | 158 | return hash_finish(hash_add64(basis, x), 8); |
965607c8 AZ |
159 | } |
160 | ||
aae7c34f | 161 | static inline uint32_t hash_uint64(const uint64_t x) |
7e36ac42 | 162 | { |
aae7c34f | 163 | return hash_uint64_basis(x, 0); |
7e36ac42 | 164 | } |
ff8eeabd JR |
165 | |
166 | #else /* __SSE4_2__ && __x86_64__ */ | |
167 | #include <smmintrin.h> | |
168 | ||
169 | static inline uint32_t hash_add(uint32_t hash, uint32_t data) | |
170 | { | |
171 | return _mm_crc32_u32(hash, data); | |
172 | } | |
173 | ||
aae7c34f JR |
174 | /* Add the halves of 'data' in the memory order. */ |
175 | static inline uint32_t hash_add64(uint32_t hash, uint64_t data) | |
176 | { | |
177 | return _mm_crc32_u64(hash, data); | |
178 | } | |
179 | ||
ff8eeabd JR |
180 | static inline uint32_t hash_finish(uint64_t hash, uint64_t final) |
181 | { | |
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. */ | |
186 | } | |
187 | ||
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__. | |
190 | * | |
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) | |
195 | { | |
196 | const uint64_t *p = (const void *)p_; | |
197 | uint64_t hash1 = basis; | |
198 | uint64_t hash2 = 0; | |
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; | |
202 | ||
203 | while (p <= limit) { | |
204 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
205 | hash2 = _mm_crc32_u64(hash2, p[1]); | |
206 | hash3 = _mm_crc32_u64(hash3, p[2]); | |
207 | p += 3; | |
208 | } | |
209 | switch (endp - (const uint32_t *)p) { | |
210 | case 1: | |
211 | hash1 = _mm_crc32_u32(hash1, *(const uint32_t *)&p[0]); | |
212 | break; | |
213 | case 2: | |
214 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
215 | break; | |
216 | case 3: | |
217 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
218 | hash2 = _mm_crc32_u32(hash2, *(const uint32_t *)&p[1]); | |
219 | break; | |
220 | case 4: | |
221 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
222 | hash2 = _mm_crc32_u64(hash2, p[1]); | |
223 | break; | |
224 | case 5: | |
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]); | |
228 | break; | |
229 | } | |
230 | return hash_finish(hash1, hash2 << 32 | hash3); | |
231 | } | |
232 | ||
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 | |
4ad07ad7 | 236 | hash_words64_inline(const uint64_t p[], size_t n_words, uint32_t basis) |
ff8eeabd | 237 | { |
4ad07ad7 JR |
238 | uint64_t hash1 = basis; |
239 | uint64_t hash2 = 0; | |
ff8eeabd JR |
240 | uint64_t hash3 = n_words; |
241 | const uint64_t *endp = p + n_words; | |
242 | const uint64_t *limit = endp - 3; | |
243 | ||
244 | while (p <= limit) { | |
245 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
246 | hash2 = _mm_crc32_u64(hash2, p[1]); | |
247 | hash3 = _mm_crc32_u64(hash3, p[2]); | |
248 | p += 3; | |
249 | } | |
250 | switch (endp - p) { | |
251 | case 1: | |
252 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
253 | break; | |
254 | case 2: | |
255 | hash1 = _mm_crc32_u64(hash1, p[0]); | |
256 | hash2 = _mm_crc32_u64(hash2, p[1]); | |
257 | break; | |
258 | } | |
259 | return hash_finish(hash1, hash2 << 32 | hash3); | |
260 | } | |
261 | ||
262 | static inline uint32_t hash_uint64_basis(const uint64_t x, | |
263 | const uint32_t basis) | |
264 | { | |
265 | /* '23' chosen to mix bits enough for the test-hash to pass. */ | |
aae7c34f | 266 | return hash_finish(hash_add64(basis, x), 23); |
ff8eeabd JR |
267 | } |
268 | ||
269 | static inline uint32_t hash_uint64(const uint64_t x) | |
270 | { | |
271 | return hash_uint64_basis(x, 0); | |
272 | } | |
273 | ||
274 | static inline uint32_t hash_2words(uint32_t x, uint32_t y) | |
275 | { | |
276 | return hash_uint64((uint64_t)y << 32 | x); | |
277 | } | |
278 | ||
279 | static inline uint32_t hash_pointer(const void *p, uint32_t basis) | |
280 | { | |
281 | return hash_uint64_basis((uint64_t) (uintptr_t) p, basis); | |
282 | } | |
283 | #endif | |
284 | ||
285 | uint32_t hash_words__(const uint32_t p[], size_t n_words, uint32_t basis); | |
4ad07ad7 | 286 | uint32_t hash_words64__(const uint64_t p[], size_t n_words, uint32_t basis); |
ff8eeabd JR |
287 | |
288 | /* Inline the larger hash functions only when 'n_words' is known to be | |
289 | * compile-time constant. */ | |
290 | #if __GNUC__ >= 4 | |
291 | static inline uint32_t | |
292 | hash_words(const uint32_t p[], size_t n_words, uint32_t basis) | |
293 | { | |
294 | if (__builtin_constant_p(n_words)) { | |
295 | return hash_words_inline(p, n_words, basis); | |
296 | } else { | |
297 | return hash_words__(p, n_words, basis); | |
298 | } | |
299 | } | |
300 | ||
301 | static inline uint32_t | |
4ad07ad7 | 302 | hash_words64(const uint64_t p[], size_t n_words, uint32_t basis) |
ff8eeabd JR |
303 | { |
304 | if (__builtin_constant_p(n_words)) { | |
305 | return hash_words64_inline(p, n_words, basis); | |
306 | } else { | |
307 | return hash_words64__(p, n_words, basis); | |
308 | } | |
309 | } | |
310 | ||
311 | #else | |
312 | ||
313 | static inline uint32_t | |
314 | hash_words(const uint32_t p[], size_t n_words, uint32_t basis) | |
315 | { | |
316 | return hash_words__(p, n_words, basis); | |
317 | } | |
318 | ||
319 | static inline uint32_t | |
4ad07ad7 | 320 | hash_words64(const uint64_t p[], size_t n_words, uint32_t basis) |
ff8eeabd JR |
321 | { |
322 | return hash_words64__(p, n_words, basis); | |
323 | } | |
324 | #endif | |
325 | ||
326 | static inline uint32_t hash_string(const char *s, uint32_t basis) | |
327 | { | |
328 | return hash_bytes(s, strlen(s), basis); | |
329 | } | |
330 | ||
331 | static inline uint32_t hash_int(uint32_t x, uint32_t basis) | |
332 | { | |
333 | return hash_2words(x, basis); | |
334 | } | |
335 | ||
336 | /* An attempt at a useful 1-bit hash function. Has not been analyzed for | |
337 | * quality. */ | |
338 | static inline uint32_t hash_boolean(bool x, uint32_t basis) | |
339 | { | |
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); | |
343 | } | |
344 | ||
43d1478b CB |
345 | #ifdef __cplusplus |
346 | } | |
347 | #endif | |
348 | ||
064af421 | 349 | #endif /* hash.h */ |