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1 // Copyright 2011 the V8 project authors. All rights reserved. | 1 // Copyright 2011 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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230 // Extracts the bit field from the value. | 230 // Extracts the bit field from the value. |
231 static T decode(uint32_t value) { | 231 static T decode(uint32_t value) { |
232 return static_cast<T>((value & kMask) >> shift); | 232 return static_cast<T>((value & kMask) >> shift); |
233 } | 233 } |
234 }; | 234 }; |
235 | 235 |
236 | 236 |
237 // ---------------------------------------------------------------------------- | 237 // ---------------------------------------------------------------------------- |
238 // Hash function. | 238 // Hash function. |
239 | 239 |
| 240 static const uint32_t kZeroHashSeed = 0; |
| 241 |
240 // Thomas Wang, Integer Hash Functions. | 242 // Thomas Wang, Integer Hash Functions. |
241 // http://www.concentric.net/~Ttwang/tech/inthash.htm | 243 // http://www.concentric.net/~Ttwang/tech/inthash.htm |
242 static inline uint32_t ComputeIntegerHash(uint32_t key) { | 244 static inline uint32_t ComputeIntegerHash(uint32_t key, uint32_t seed) { |
243 uint32_t hash = key; | 245 uint32_t hash = key; |
| 246 hash = hash ^ seed; |
244 hash = ~hash + (hash << 15); // hash = (hash << 15) - hash - 1; | 247 hash = ~hash + (hash << 15); // hash = (hash << 15) - hash - 1; |
245 hash = hash ^ (hash >> 12); | 248 hash = hash ^ (hash >> 12); |
246 hash = hash + (hash << 2); | 249 hash = hash + (hash << 2); |
247 hash = hash ^ (hash >> 4); | 250 hash = hash ^ (hash >> 4); |
248 hash = hash * 2057; // hash = (hash + (hash << 3)) + (hash << 11); | 251 hash = hash * 2057; // hash = (hash + (hash << 3)) + (hash << 11); |
249 hash = hash ^ (hash >> 16); | 252 hash = hash ^ (hash >> 16); |
250 return hash; | 253 return hash; |
251 } | 254 } |
252 | 255 |
253 | 256 |
254 static inline uint32_t ComputePointerHash(void* ptr) { | 257 static inline uint32_t ComputePointerHash(void* ptr) { |
255 return ComputeIntegerHash( | 258 return ComputeIntegerHash( |
256 static_cast<uint32_t>(reinterpret_cast<intptr_t>(ptr))); | 259 static_cast<uint32_t>(reinterpret_cast<intptr_t>(ptr)), |
| 260 v8::internal::kZeroHashSeed); |
257 } | 261 } |
258 | 262 |
259 | 263 |
260 // ---------------------------------------------------------------------------- | 264 // ---------------------------------------------------------------------------- |
261 // Miscellaneous | 265 // Miscellaneous |
262 | 266 |
263 // A static resource holds a static instance that can be reserved in | 267 // A static resource holds a static instance that can be reserved in |
264 // a local scope using an instance of Access. Attempts to re-reserve | 268 // a local scope using an instance of Access. Attempts to re-reserve |
265 // the instance will cause an error. | 269 // the instance will cause an error. |
266 template <typename T> | 270 template <typename T> |
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911 ASSERT(element < static_cast<int>(sizeof(T) * CHAR_BIT)); | 915 ASSERT(element < static_cast<int>(sizeof(T) * CHAR_BIT)); |
912 return 1 << element; | 916 return 1 << element; |
913 } | 917 } |
914 | 918 |
915 T bits_; | 919 T bits_; |
916 }; | 920 }; |
917 | 921 |
918 } } // namespace v8::internal | 922 } } // namespace v8::internal |
919 | 923 |
920 #endif // V8_UTILS_H_ | 924 #endif // V8_UTILS_H_ |
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