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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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247 return static_cast<T>((value & kMask) >> shift); | 247 return static_cast<T>((value & kMask) >> shift); |
248 } | 248 } |
249 }; | 249 }; |
250 | 250 |
251 | 251 |
252 // ---------------------------------------------------------------------------- | 252 // ---------------------------------------------------------------------------- |
253 // Hash function. | 253 // Hash function. |
254 | 254 |
255 // Thomas Wang, Integer Hash Functions. | 255 // Thomas Wang, Integer Hash Functions. |
256 // http://www.concentric.net/~Ttwang/tech/inthash.htm | 256 // http://www.concentric.net/~Ttwang/tech/inthash.htm |
257 inline uint32_t ComputeIntegerHash(uint32_t key) { | 257 inline uint32_t ComputeIntegerHash(uint32_t key, uint32_t seed = 0) { |
Erik Corry
2012/01/10 11:53:16
No default arguments.
| |
258 uint32_t hash = key; | 258 uint32_t hash = key; |
259 hash = hash ^ seed; | |
259 hash = ~hash + (hash << 15); // hash = (hash << 15) - hash - 1; | 260 hash = ~hash + (hash << 15); // hash = (hash << 15) - hash - 1; |
260 hash = hash ^ (hash >> 12); | 261 hash = hash ^ (hash >> 12); |
261 hash = hash + (hash << 2); | 262 hash = hash + (hash << 2); |
262 hash = hash ^ (hash >> 4); | 263 hash = hash ^ (hash >> 4); |
263 hash = hash * 2057; // hash = (hash + (hash << 3)) + (hash << 11); | 264 hash = hash * 2057; // hash = (hash + (hash << 3)) + (hash << 11); |
264 hash = hash ^ (hash >> 16); | 265 hash = hash ^ (hash >> 16); |
265 return hash; | 266 return hash; |
266 } | 267 } |
267 | 268 |
268 | 269 |
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938 ASSERT(element < static_cast<int>(sizeof(T) * CHAR_BIT)); | 939 ASSERT(element < static_cast<int>(sizeof(T) * CHAR_BIT)); |
939 return 1 << element; | 940 return 1 << element; |
940 } | 941 } |
941 | 942 |
942 T bits_; | 943 T bits_; |
943 }; | 944 }; |
944 | 945 |
945 } } // namespace v8::internal | 946 } } // namespace v8::internal |
946 | 947 |
947 #endif // V8_UTILS_H_ | 948 #endif // V8_UTILS_H_ |
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