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1 // Copyright 2006-2008 the V8 project authors. All rights reserved. | 1 // Copyright 2006-2008 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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35 namespace v8 { | 35 namespace v8 { |
36 namespace internal { | 36 namespace internal { |
37 | 37 |
38 struct CachedPower { | 38 struct CachedPower { |
39 uint64_t significand; | 39 uint64_t significand; |
40 int16_t binary_exponent; | 40 int16_t binary_exponent; |
41 int16_t decimal_exponent; | 41 int16_t decimal_exponent; |
42 }; | 42 }; |
43 | 43 |
44 static const CachedPower kCachedPowers[] = { | 44 static const CachedPower kCachedPowers[] = { |
| 45 {V8_2PART_UINT64_C(0xfa8fd5a0, 081c0288), -1220, -348}, |
| 46 {V8_2PART_UINT64_C(0xbaaee17f, a23ebf76), -1193, -340}, |
| 47 {V8_2PART_UINT64_C(0x8b16fb20, 3055ac76), -1166, -332}, |
| 48 {V8_2PART_UINT64_C(0xcf42894a, 5dce35ea), -1140, -324}, |
| 49 {V8_2PART_UINT64_C(0x9a6bb0aa, 55653b2d), -1113, -316}, |
45 {V8_2PART_UINT64_C(0xe61acf03, 3d1a45df), -1087, -308}, | 50 {V8_2PART_UINT64_C(0xe61acf03, 3d1a45df), -1087, -308}, |
46 {V8_2PART_UINT64_C(0xab70fe17, c79ac6ca), -1060, -300}, | 51 {V8_2PART_UINT64_C(0xab70fe17, c79ac6ca), -1060, -300}, |
47 {V8_2PART_UINT64_C(0xff77b1fc, bebcdc4f), -1034, -292}, | 52 {V8_2PART_UINT64_C(0xff77b1fc, bebcdc4f), -1034, -292}, |
48 {V8_2PART_UINT64_C(0xbe5691ef, 416bd60c), -1007, -284}, | 53 {V8_2PART_UINT64_C(0xbe5691ef, 416bd60c), -1007, -284}, |
49 {V8_2PART_UINT64_C(0x8dd01fad, 907ffc3c), -980, -276}, | 54 {V8_2PART_UINT64_C(0x8dd01fad, 907ffc3c), -980, -276}, |
50 {V8_2PART_UINT64_C(0xd3515c28, 31559a83), -954, -268}, | 55 {V8_2PART_UINT64_C(0xd3515c28, 31559a83), -954, -268}, |
51 {V8_2PART_UINT64_C(0x9d71ac8f, ada6c9b5), -927, -260}, | 56 {V8_2PART_UINT64_C(0x9d71ac8f, ada6c9b5), -927, -260}, |
52 {V8_2PART_UINT64_C(0xea9c2277, 23ee8bcb), -901, -252}, | 57 {V8_2PART_UINT64_C(0xea9c2277, 23ee8bcb), -901, -252}, |
53 {V8_2PART_UINT64_C(0xaecc4991, 4078536d), -874, -244}, | 58 {V8_2PART_UINT64_C(0xaecc4991, 4078536d), -874, -244}, |
54 {V8_2PART_UINT64_C(0x823c1279, 5db6ce57), -847, -236}, | 59 {V8_2PART_UINT64_C(0x823c1279, 5db6ce57), -847, -236}, |
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122 {V8_2PART_UINT64_C(0x8e679c2f, 5e44ff8f), 960, 308}, | 127 {V8_2PART_UINT64_C(0x8e679c2f, 5e44ff8f), 960, 308}, |
123 {V8_2PART_UINT64_C(0xd433179d, 9c8cb841), 986, 316}, | 128 {V8_2PART_UINT64_C(0xd433179d, 9c8cb841), 986, 316}, |
124 {V8_2PART_UINT64_C(0x9e19db92, b4e31ba9), 1013, 324}, | 129 {V8_2PART_UINT64_C(0x9e19db92, b4e31ba9), 1013, 324}, |
125 {V8_2PART_UINT64_C(0xeb96bf6e, badf77d9), 1039, 332}, | 130 {V8_2PART_UINT64_C(0xeb96bf6e, badf77d9), 1039, 332}, |
126 {V8_2PART_UINT64_C(0xaf87023b, 9bf0ee6b), 1066, 340}, | 131 {V8_2PART_UINT64_C(0xaf87023b, 9bf0ee6b), 1066, 340}, |
127 }; | 132 }; |
128 | 133 |
129 static const int kCachedPowersLength = ARRAY_SIZE(kCachedPowers); | 134 static const int kCachedPowersLength = ARRAY_SIZE(kCachedPowers); |
130 static const int kCachedPowersOffset = -kCachedPowers[0].decimal_exponent; | 135 static const int kCachedPowersOffset = -kCachedPowers[0].decimal_exponent; |
131 static const double kD_1_LOG2_10 = 0.30102999566398114; // 1 / lg(10) | 136 static const double kD_1_LOG2_10 = 0.30102999566398114; // 1 / lg(10) |
132 static const int kCachedPowersDecimalDistance = | 137 const int PowersOfTenCache::kDecimalExponentDistance = |
133 kCachedPowers[1].decimal_exponent - kCachedPowers[0].decimal_exponent; | 138 kCachedPowers[1].decimal_exponent - kCachedPowers[0].decimal_exponent; |
| 139 const int PowersOfTenCache::kMinDecimalExponent = |
| 140 kCachedPowers[0].decimal_exponent; |
| 141 const int PowersOfTenCache::kMaxDecimalExponent = |
| 142 kCachedPowers[kCachedPowersLength - 1].decimal_exponent; |
134 | 143 |
135 void GetCachedPowerForBinaryExponentRange(int min_exponent, | 144 void PowersOfTenCache::GetCachedPowerForBinaryExponentRange( |
136 int max_exponent, | 145 int min_exponent, |
137 DiyFp* power, | 146 int max_exponent, |
138 int* decimal_exponent) { | 147 DiyFp* power, |
139 int kQ = DiyFp::kSignificandSize; | 148 int* decimal_exponent) { |
140 double k = ceiling((min_exponent + kQ - 1) * kD_1_LOG2_10); | 149 int kQ = DiyFp::kSignificandSize; |
141 int foo = kCachedPowersOffset; | 150 double k = ceiling((min_exponent + kQ - 1) * kD_1_LOG2_10); |
142 int index = | 151 int foo = kCachedPowersOffset; |
143 (foo + static_cast<int>(k) - 1) / kCachedPowersDecimalDistance + 1; | 152 int index = |
144 ASSERT(0 <= index && index < kCachedPowersLength); | 153 (foo + static_cast<int>(k) - 1) / kDecimalExponentDistance + 1; |
145 CachedPower cached_power = kCachedPowers[index]; | 154 ASSERT(0 <= index && index < kCachedPowersLength); |
146 ASSERT(min_exponent <= cached_power.binary_exponent); | 155 CachedPower cached_power = kCachedPowers[index]; |
147 ASSERT(cached_power.binary_exponent <= max_exponent); | 156 ASSERT(min_exponent <= cached_power.binary_exponent); |
148 *decimal_exponent = cached_power.decimal_exponent; | 157 ASSERT(cached_power.binary_exponent <= max_exponent); |
149 *power = DiyFp(cached_power.significand, cached_power.binary_exponent); | 158 *decimal_exponent = cached_power.decimal_exponent; |
| 159 *power = DiyFp(cached_power.significand, cached_power.binary_exponent); |
| 160 } |
| 161 |
| 162 |
| 163 void PowersOfTenCache::GetCachedPowerForDecimalExponent(int requested_exponent, |
| 164 DiyFp* power, |
| 165 int* found_exponent) { |
| 166 ASSERT(kMinDecimalExponent <= requested_exponent); |
| 167 ASSERT(requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance); |
| 168 int index = |
| 169 (requested_exponent + kCachedPowersOffset) / kDecimalExponentDistance; |
| 170 CachedPower cached_power = kCachedPowers[index]; |
| 171 *power = DiyFp(cached_power.significand, cached_power.binary_exponent); |
| 172 *found_exponent = cached_power.decimal_exponent; |
| 173 ASSERT(*found_exponent <= requested_exponent); |
| 174 ASSERT(requested_exponent < *found_exponent + kDecimalExponentDistance); |
150 } | 175 } |
151 | 176 |
152 } } // namespace v8::internal | 177 } } // namespace v8::internal |
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