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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 // | 4 // |
5 // Defines methods for hashing a pair of integers. | 5 // Defines methods for hashing a pair of integers. |
6 | 6 |
7 #ifndef CC_BASE_HASH_PAIR_H_ | 7 #ifndef CC_BASE_HASH_PAIR_H_ |
8 #define CC_BASE_HASH_PAIR_H_ | 8 #define CC_BASE_HASH_PAIR_H_ |
9 | 9 |
| 10 #include <utility> |
| 11 |
| 12 #include "base/basictypes.h" |
10 #include "base/hash_tables.h" | 13 #include "base/hash_tables.h" |
11 | 14 |
12 #if defined(COMPILER_MSVC) | 15 #if defined(COMPILER_MSVC) |
13 | 16 |
14 #define DEFINE_PAIR_HASH_FUNCTION_START(type1, type2) \ | 17 #define DEFINE_PAIR_HASH_FUNCTION_START(type1, type2) \ |
15 template<> \ | 18 template<> \ |
16 inline std::size_t hash_value<std::pair<type1, type2> >( \ | 19 inline std::size_t hash_value<std::pair<type1, type2> >( \ |
17 const std::pair<type1, type2>& value) | 20 const std::pair<type1, type2>& value) |
18 | 21 |
19 #define DEFINE_PAIR_HASH_FUNCTION_END() | 22 #define DEFINE_PAIR_HASH_FUNCTION_END() |
20 | 23 |
21 #elif defined(COMPILER_GCC) | 24 #elif defined(COMPILER_GCC) |
22 | 25 |
23 #define DEFINE_PAIR_HASH_FUNCTION_START(type1, type2) \ | 26 #define DEFINE_PAIR_HASH_FUNCTION_START(type1, type2) \ |
24 template<> \ | 27 template<> \ |
25 struct hash<std::pair<type1, type2> > { \ | 28 struct hash<std::pair<type1, type2> > { \ |
26 std::size_t operator()(std::pair<type1, type2> value) const | 29 std::size_t operator()(std::pair<type1, type2> value) const |
27 | 30 |
28 #define DEFINE_PAIR_HASH_FUNCTION_END() \ | 31 #define DEFINE_PAIR_HASH_FUNCTION_END() \ |
29 }; | 32 }; |
30 | 33 |
31 #else | 34 #else |
32 #error define DEFINE_PAIR_HASH_FUNCTION_START for your compiler | 35 #error define DEFINE_PAIR_HASH_FUNCTION_START for your compiler |
33 #endif // COMPILER | 36 #endif // COMPILER |
34 | 37 |
35 namespace BASE_HASH_NAMESPACE { | 38 namespace BASE_HASH_NAMESPACE { |
36 | 39 |
37 // Implement hashing for pairs of at-most 32 bit integer values. | 40 // Implement hashing for pairs of at-most 32 bit integer values. |
38 // When size_t is 32 bits, we turn the 64-bit hash code into 32 bits by using | 41 // When size_t is 32 bits, we turn the 64-bit hash code into 32 bits by using |
39 // multiply-add hashing. This algorithm, as described in | 42 // multiply-add hashing. This algorithm, as described in |
40 // Theorem 4.3.3 of the thesis "Über die Komplexität der Multiplikation in | 43 // Theorem 4.3.3 of the thesis "Über die Komplexität der Multiplikation in |
41 // eingeschränkten Branchingprogrammmodellen" by Woelfel, is: | 44 // eingeschränkten Branchingprogrammmodellen" by Woelfel, is: |
42 // | 45 // |
43 // h32(x32, y32) = (h64(x32, y32) * rand_odd64 + rand16 * 2^16) % 2^64 / 2^32 | 46 // h32(x32, y32) = (h64(x32, y32) * rand_odd64 + rand16 * 2^16) % 2^64 / 2^32 |
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54 uint64 odd_random = 481046412LL << 32 | 1025306954LL; \ | 57 uint64 odd_random = 481046412LL << 32 | 1025306954LL; \ |
55 uint32 shift_random = 10121U << 16; \ | 58 uint32 shift_random = 10121U << 16; \ |
56 \ | 59 \ |
57 hash64 = hash64 * odd_random + shift_random; \ | 60 hash64 = hash64 * odd_random + shift_random; \ |
58 std::size_t high_bits = static_cast<std::size_t>( \ | 61 std::size_t high_bits = static_cast<std::size_t>( \ |
59 hash64 >> (sizeof(uint64) - sizeof(std::size_t))); \ | 62 hash64 >> (sizeof(uint64) - sizeof(std::size_t))); \ |
60 return high_bits; \ | 63 return high_bits; \ |
61 } \ | 64 } \ |
62 DEFINE_PAIR_HASH_FUNCTION_END(); | 65 DEFINE_PAIR_HASH_FUNCTION_END(); |
63 | 66 |
64 DEFINE_32BIT_PAIR_HASH(short, short); | 67 DEFINE_32BIT_PAIR_HASH(int16, int16); |
65 DEFINE_32BIT_PAIR_HASH(short, unsigned short); | 68 DEFINE_32BIT_PAIR_HASH(int16, uint16); |
66 DEFINE_32BIT_PAIR_HASH(short, int); | 69 DEFINE_32BIT_PAIR_HASH(int16, int32); |
67 DEFINE_32BIT_PAIR_HASH(short, unsigned); | 70 DEFINE_32BIT_PAIR_HASH(int16, uint32); |
68 DEFINE_32BIT_PAIR_HASH(unsigned short, short); | 71 DEFINE_32BIT_PAIR_HASH(uint16, int16); |
69 DEFINE_32BIT_PAIR_HASH(unsigned short, unsigned short); | 72 DEFINE_32BIT_PAIR_HASH(uint16, uint16); |
70 DEFINE_32BIT_PAIR_HASH(unsigned short, int); | 73 DEFINE_32BIT_PAIR_HASH(uint16, int32); |
71 DEFINE_32BIT_PAIR_HASH(unsigned short, unsigned); | 74 DEFINE_32BIT_PAIR_HASH(uint16, uint32); |
72 DEFINE_32BIT_PAIR_HASH(int, short); | 75 DEFINE_32BIT_PAIR_HASH(int32, int16); |
73 DEFINE_32BIT_PAIR_HASH(int, unsigned short); | 76 DEFINE_32BIT_PAIR_HASH(int32, uint16); |
74 DEFINE_32BIT_PAIR_HASH(int, int); | 77 DEFINE_32BIT_PAIR_HASH(int32, int32); |
75 DEFINE_32BIT_PAIR_HASH(int, unsigned); | 78 DEFINE_32BIT_PAIR_HASH(int32, uint32); |
76 DEFINE_32BIT_PAIR_HASH(unsigned, short); | 79 DEFINE_32BIT_PAIR_HASH(uint32, int16); |
77 DEFINE_32BIT_PAIR_HASH(unsigned, unsigned short); | 80 DEFINE_32BIT_PAIR_HASH(uint32, uint16); |
78 DEFINE_32BIT_PAIR_HASH(unsigned, int); | 81 DEFINE_32BIT_PAIR_HASH(uint32, int32); |
79 DEFINE_32BIT_PAIR_HASH(unsigned, unsigned); | 82 DEFINE_32BIT_PAIR_HASH(uint32, uint32); |
80 | 83 |
81 #undef DEFINE_32BIT_PAIR_HASH | 84 #undef DEFINE_32BIT_PAIR_HASH |
82 | 85 |
83 // Implement hashing for pairs of up-to 64-bit integer values. | 86 // Implement hashing for pairs of up-to 64-bit integer values. |
84 // We use the compound integer hash method to produce a 64-bit hash code, by | 87 // We use the compound integer hash method to produce a 64-bit hash code, by |
85 // breaking the two 64-bit inputs into 4 32-bit values: | 88 // breaking the two 64-bit inputs into 4 32-bit values: |
86 // http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECT
ION00832000000000000000 | 89 // http://opendatastructures.org/versions/edition-0.1d/ods-java/node33.html#SECT
ION00832000000000000000 |
87 // Then we reduce our result to 32 bits if required, similar to above. | 90 // Then we reduce our result to 32 bits if required, similar to above. |
88 | 91 |
89 #define DEFINE_64BIT_PAIR_HASH(type1, type2) \ | 92 #define DEFINE_64BIT_PAIR_HASH(type1, type2) \ |
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113 uint64 odd_random = 1578233944LL << 32 | 194370989LL; \ | 116 uint64 odd_random = 1578233944LL << 32 | 194370989LL; \ |
114 uint32 shift_random = 20591U << 16; \ | 117 uint32 shift_random = 20591U << 16; \ |
115 \ | 118 \ |
116 hash64 = hash64 * odd_random + shift_random; \ | 119 hash64 = hash64 * odd_random + shift_random; \ |
117 std::size_t high_bits = static_cast<std::size_t>( \ | 120 std::size_t high_bits = static_cast<std::size_t>( \ |
118 hash64 >> (sizeof(uint64) - sizeof(std::size_t))); \ | 121 hash64 >> (sizeof(uint64) - sizeof(std::size_t))); \ |
119 return high_bits; \ | 122 return high_bits; \ |
120 } \ | 123 } \ |
121 DEFINE_PAIR_HASH_FUNCTION_END(); | 124 DEFINE_PAIR_HASH_FUNCTION_END(); |
122 | 125 |
123 DEFINE_64BIT_PAIR_HASH(short, int64); | 126 DEFINE_64BIT_PAIR_HASH(int16, int64); |
124 DEFINE_64BIT_PAIR_HASH(short, uint64); | 127 DEFINE_64BIT_PAIR_HASH(int16, uint64); |
125 DEFINE_64BIT_PAIR_HASH(unsigned short, int64); | 128 DEFINE_64BIT_PAIR_HASH(uint16, int64); |
126 DEFINE_64BIT_PAIR_HASH(unsigned short, uint64); | 129 DEFINE_64BIT_PAIR_HASH(uint16, uint64); |
127 DEFINE_64BIT_PAIR_HASH(int, int64); | 130 DEFINE_64BIT_PAIR_HASH(int32, int64); |
128 DEFINE_64BIT_PAIR_HASH(int, uint64); | 131 DEFINE_64BIT_PAIR_HASH(int32, uint64); |
129 DEFINE_64BIT_PAIR_HASH(unsigned, int64); | 132 DEFINE_64BIT_PAIR_HASH(uint32, int64); |
130 DEFINE_64BIT_PAIR_HASH(unsigned, uint64); | 133 DEFINE_64BIT_PAIR_HASH(uint32, uint64); |
131 DEFINE_64BIT_PAIR_HASH(int64, short); | 134 DEFINE_64BIT_PAIR_HASH(int64, int16); |
132 DEFINE_64BIT_PAIR_HASH(int64, unsigned short); | 135 DEFINE_64BIT_PAIR_HASH(int64, uint16); |
133 DEFINE_64BIT_PAIR_HASH(int64, int); | 136 DEFINE_64BIT_PAIR_HASH(int64, int32); |
134 DEFINE_64BIT_PAIR_HASH(int64, unsigned); | 137 DEFINE_64BIT_PAIR_HASH(int64, uint32); |
135 DEFINE_64BIT_PAIR_HASH(int64, int64); | 138 DEFINE_64BIT_PAIR_HASH(int64, int64); |
136 DEFINE_64BIT_PAIR_HASH(int64, uint64); | 139 DEFINE_64BIT_PAIR_HASH(int64, uint64); |
137 DEFINE_64BIT_PAIR_HASH(uint64, short); | 140 DEFINE_64BIT_PAIR_HASH(uint64, int16); |
138 DEFINE_64BIT_PAIR_HASH(uint64, unsigned short); | 141 DEFINE_64BIT_PAIR_HASH(uint64, uint16); |
139 DEFINE_64BIT_PAIR_HASH(uint64, int); | 142 DEFINE_64BIT_PAIR_HASH(uint64, int32); |
140 DEFINE_64BIT_PAIR_HASH(uint64, unsigned); | 143 DEFINE_64BIT_PAIR_HASH(uint64, uint32); |
141 DEFINE_64BIT_PAIR_HASH(uint64, int64); | 144 DEFINE_64BIT_PAIR_HASH(uint64, int64); |
142 DEFINE_64BIT_PAIR_HASH(uint64, uint64); | 145 DEFINE_64BIT_PAIR_HASH(uint64, uint64); |
143 | 146 |
144 #undef DEFINE_64BIT_PAIR_HASH | 147 #undef DEFINE_64BIT_PAIR_HASH |
145 } | 148 } |
146 | 149 |
147 #undef DEFINE_PAIR_HASH_FUNCTION_START | 150 #undef DEFINE_PAIR_HASH_FUNCTION_START |
148 #undef DEFINE_PAIR_HASH_FUNCTION_END | 151 #undef DEFINE_PAIR_HASH_FUNCTION_END |
149 | 152 |
150 #endif // CC_BASE_HASH_PAIR_H_ | 153 #endif // CC_BASE_HASH_PAIR_H_ |
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