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comparison: mfbt/double-conversion/cached-powers.cc
mfbt/double-conversion/cached-powers.cc
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- changeset 8
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| -1:000000000000 | 0:25415a032572 |
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| 1 // Copyright 2006-2008 the V8 project authors. All rights reserved. | |
| 2 // Redistribution and use in source and binary forms, with or without | |
| 3 // modification, are permitted provided that the following conditions are | |
| 4 // met: | |
| 5 // | |
| 6 // * Redistributions of source code must retain the above copyright | |
| 7 // notice, this list of conditions and the following disclaimer. | |
| 8 // * Redistributions in binary form must reproduce the above | |
| 9 // copyright notice, this list of conditions and the following | |
| 10 // disclaimer in the documentation and/or other materials provided | |
| 11 // with the distribution. | |
| 12 // * Neither the name of Google Inc. nor the names of its | |
| 13 // contributors may be used to endorse or promote products derived | |
| 14 // from this software without specific prior written permission. | |
| 15 // | |
| 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 27 | |
| 28 #include <stdarg.h> | |
| 29 #include <limits.h> | |
| 30 #include <math.h> | |
| 31 | |
| 32 #include "utils.h" | |
| 33 | |
| 34 #include "cached-powers.h" | |
| 35 | |
| 36 namespace double_conversion { | |
| 37 | |
| 38 struct CachedPower { | |
| 39 uint64_t significand; | |
| 40 int16_t binary_exponent; | |
| 41 int16_t decimal_exponent; | |
| 42 }; | |
| 43 | |
| 44 static const CachedPower kCachedPowers[] = { | |
| 45 {UINT64_2PART_C(0xfa8fd5a0, 081c0288), -1220, -348}, | |
| 46 {UINT64_2PART_C(0xbaaee17f, a23ebf76), -1193, -340}, | |
| 47 {UINT64_2PART_C(0x8b16fb20, 3055ac76), -1166, -332}, | |
| 48 {UINT64_2PART_C(0xcf42894a, 5dce35ea), -1140, -324}, | |
| 49 {UINT64_2PART_C(0x9a6bb0aa, 55653b2d), -1113, -316}, | |
| 50 {UINT64_2PART_C(0xe61acf03, 3d1a45df), -1087, -308}, | |
| 51 {UINT64_2PART_C(0xab70fe17, c79ac6ca), -1060, -300}, | |
| 52 {UINT64_2PART_C(0xff77b1fc, bebcdc4f), -1034, -292}, | |
| 53 {UINT64_2PART_C(0xbe5691ef, 416bd60c), -1007, -284}, | |
| 54 {UINT64_2PART_C(0x8dd01fad, 907ffc3c), -980, -276}, | |
| 55 {UINT64_2PART_C(0xd3515c28, 31559a83), -954, -268}, | |
| 56 {UINT64_2PART_C(0x9d71ac8f, ada6c9b5), -927, -260}, | |
| 57 {UINT64_2PART_C(0xea9c2277, 23ee8bcb), -901, -252}, | |
| 58 {UINT64_2PART_C(0xaecc4991, 4078536d), -874, -244}, | |
| 59 {UINT64_2PART_C(0x823c1279, 5db6ce57), -847, -236}, | |
| 60 {UINT64_2PART_C(0xc2109436, 4dfb5637), -821, -228}, | |
| 61 {UINT64_2PART_C(0x9096ea6f, 3848984f), -794, -220}, | |
| 62 {UINT64_2PART_C(0xd77485cb, 25823ac7), -768, -212}, | |
| 63 {UINT64_2PART_C(0xa086cfcd, 97bf97f4), -741, -204}, | |
| 64 {UINT64_2PART_C(0xef340a98, 172aace5), -715, -196}, | |
| 65 {UINT64_2PART_C(0xb23867fb, 2a35b28e), -688, -188}, | |
| 66 {UINT64_2PART_C(0x84c8d4df, d2c63f3b), -661, -180}, | |
| 67 {UINT64_2PART_C(0xc5dd4427, 1ad3cdba), -635, -172}, | |
| 68 {UINT64_2PART_C(0x936b9fce, bb25c996), -608, -164}, | |
| 69 {UINT64_2PART_C(0xdbac6c24, 7d62a584), -582, -156}, | |
| 70 {UINT64_2PART_C(0xa3ab6658, 0d5fdaf6), -555, -148}, | |
| 71 {UINT64_2PART_C(0xf3e2f893, dec3f126), -529, -140}, | |
| 72 {UINT64_2PART_C(0xb5b5ada8, aaff80b8), -502, -132}, | |
| 73 {UINT64_2PART_C(0x87625f05, 6c7c4a8b), -475, -124}, | |
| 74 {UINT64_2PART_C(0xc9bcff60, 34c13053), -449, -116}, | |
| 75 {UINT64_2PART_C(0x964e858c, 91ba2655), -422, -108}, | |
| 76 {UINT64_2PART_C(0xdff97724, 70297ebd), -396, -100}, | |
| 77 {UINT64_2PART_C(0xa6dfbd9f, b8e5b88f), -369, -92}, | |
| 78 {UINT64_2PART_C(0xf8a95fcf, 88747d94), -343, -84}, | |
| 79 {UINT64_2PART_C(0xb9447093, 8fa89bcf), -316, -76}, | |
| 80 {UINT64_2PART_C(0x8a08f0f8, bf0f156b), -289, -68}, | |
| 81 {UINT64_2PART_C(0xcdb02555, 653131b6), -263, -60}, | |
| 82 {UINT64_2PART_C(0x993fe2c6, d07b7fac), -236, -52}, | |
| 83 {UINT64_2PART_C(0xe45c10c4, 2a2b3b06), -210, -44}, | |
| 84 {UINT64_2PART_C(0xaa242499, 697392d3), -183, -36}, | |
| 85 {UINT64_2PART_C(0xfd87b5f2, 8300ca0e), -157, -28}, | |
| 86 {UINT64_2PART_C(0xbce50864, 92111aeb), -130, -20}, | |
| 87 {UINT64_2PART_C(0x8cbccc09, 6f5088cc), -103, -12}, | |
| 88 {UINT64_2PART_C(0xd1b71758, e219652c), -77, -4}, | |
| 89 {UINT64_2PART_C(0x9c400000, 00000000), -50, 4}, | |
| 90 {UINT64_2PART_C(0xe8d4a510, 00000000), -24, 12}, | |
| 91 {UINT64_2PART_C(0xad78ebc5, ac620000), 3, 20}, | |
| 92 {UINT64_2PART_C(0x813f3978, f8940984), 30, 28}, | |
| 93 {UINT64_2PART_C(0xc097ce7b, c90715b3), 56, 36}, | |
| 94 {UINT64_2PART_C(0x8f7e32ce, 7bea5c70), 83, 44}, | |
| 95 {UINT64_2PART_C(0xd5d238a4, abe98068), 109, 52}, | |
| 96 {UINT64_2PART_C(0x9f4f2726, 179a2245), 136, 60}, | |
| 97 {UINT64_2PART_C(0xed63a231, d4c4fb27), 162, 68}, | |
| 98 {UINT64_2PART_C(0xb0de6538, 8cc8ada8), 189, 76}, | |
| 99 {UINT64_2PART_C(0x83c7088e, 1aab65db), 216, 84}, | |
| 100 {UINT64_2PART_C(0xc45d1df9, 42711d9a), 242, 92}, | |
| 101 {UINT64_2PART_C(0x924d692c, a61be758), 269, 100}, | |
| 102 {UINT64_2PART_C(0xda01ee64, 1a708dea), 295, 108}, | |
| 103 {UINT64_2PART_C(0xa26da399, 9aef774a), 322, 116}, | |
| 104 {UINT64_2PART_C(0xf209787b, b47d6b85), 348, 124}, | |
| 105 {UINT64_2PART_C(0xb454e4a1, 79dd1877), 375, 132}, | |
| 106 {UINT64_2PART_C(0x865b8692, 5b9bc5c2), 402, 140}, | |
| 107 {UINT64_2PART_C(0xc83553c5, c8965d3d), 428, 148}, | |
| 108 {UINT64_2PART_C(0x952ab45c, fa97a0b3), 455, 156}, | |
| 109 {UINT64_2PART_C(0xde469fbd, 99a05fe3), 481, 164}, | |
| 110 {UINT64_2PART_C(0xa59bc234, db398c25), 508, 172}, | |
| 111 {UINT64_2PART_C(0xf6c69a72, a3989f5c), 534, 180}, | |
| 112 {UINT64_2PART_C(0xb7dcbf53, 54e9bece), 561, 188}, | |
| 113 {UINT64_2PART_C(0x88fcf317, f22241e2), 588, 196}, | |
| 114 {UINT64_2PART_C(0xcc20ce9b, d35c78a5), 614, 204}, | |
| 115 {UINT64_2PART_C(0x98165af3, 7b2153df), 641, 212}, | |
| 116 {UINT64_2PART_C(0xe2a0b5dc, 971f303a), 667, 220}, | |
| 117 {UINT64_2PART_C(0xa8d9d153, 5ce3b396), 694, 228}, | |
| 118 {UINT64_2PART_C(0xfb9b7cd9, a4a7443c), 720, 236}, | |
| 119 {UINT64_2PART_C(0xbb764c4c, a7a44410), 747, 244}, | |
| 120 {UINT64_2PART_C(0x8bab8eef, b6409c1a), 774, 252}, | |
| 121 {UINT64_2PART_C(0xd01fef10, a657842c), 800, 260}, | |
| 122 {UINT64_2PART_C(0x9b10a4e5, e9913129), 827, 268}, | |
| 123 {UINT64_2PART_C(0xe7109bfb, a19c0c9d), 853, 276}, | |
| 124 {UINT64_2PART_C(0xac2820d9, 623bf429), 880, 284}, | |
| 125 {UINT64_2PART_C(0x80444b5e, 7aa7cf85), 907, 292}, | |
| 126 {UINT64_2PART_C(0xbf21e440, 03acdd2d), 933, 300}, | |
| 127 {UINT64_2PART_C(0x8e679c2f, 5e44ff8f), 960, 308}, | |
| 128 {UINT64_2PART_C(0xd433179d, 9c8cb841), 986, 316}, | |
| 129 {UINT64_2PART_C(0x9e19db92, b4e31ba9), 1013, 324}, | |
| 130 {UINT64_2PART_C(0xeb96bf6e, badf77d9), 1039, 332}, | |
| 131 {UINT64_2PART_C(0xaf87023b, 9bf0ee6b), 1066, 340}, | |
| 132 }; | |
| 133 | |
| 134 static const int kCachedPowersLength = ARRAY_SIZE(kCachedPowers); | |
| 135 static const int kCachedPowersOffset = 348; // -1 * the first decimal_exponent. | |
| 136 static const double kD_1_LOG2_10 = 0.30102999566398114; // 1 / lg(10) | |
| 137 // Difference between the decimal exponents in the table above. | |
| 138 const int PowersOfTenCache::kDecimalExponentDistance = 8; | |
| 139 const int PowersOfTenCache::kMinDecimalExponent = -348; | |
| 140 const int PowersOfTenCache::kMaxDecimalExponent = 340; | |
| 141 | |
| 142 void PowersOfTenCache::GetCachedPowerForBinaryExponentRange( | |
| 143 int min_exponent, | |
| 144 int max_exponent, | |
| 145 DiyFp* power, | |
| 146 int* decimal_exponent) { | |
| 147 int kQ = DiyFp::kSignificandSize; | |
| 148 double k = ceil((min_exponent + kQ - 1) * kD_1_LOG2_10); | |
| 149 int foo = kCachedPowersOffset; | |
| 150 int index = | |
| 151 (foo + static_cast<int>(k) - 1) / kDecimalExponentDistance + 1; | |
| 152 ASSERT(0 <= index && index < kCachedPowersLength); | |
| 153 CachedPower cached_power = kCachedPowers[index]; | |
| 154 ASSERT(min_exponent <= cached_power.binary_exponent); | |
| 155 ASSERT(cached_power.binary_exponent <= max_exponent); | |
| 156 *decimal_exponent = cached_power.decimal_exponent; | |
| 157 *power = DiyFp(cached_power.significand, cached_power.binary_exponent); | |
| 158 } | |
| 159 | |
| 160 | |
| 161 void PowersOfTenCache::GetCachedPowerForDecimalExponent(int requested_exponent, | |
| 162 DiyFp* power, | |
| 163 int* found_exponent) { | |
| 164 ASSERT(kMinDecimalExponent <= requested_exponent); | |
| 165 ASSERT(requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance); | |
| 166 int index = | |
| 167 (requested_exponent + kCachedPowersOffset) / kDecimalExponentDistance; | |
| 168 CachedPower cached_power = kCachedPowers[index]; | |
| 169 *power = DiyFp(cached_power.significand, cached_power.binary_exponent); | |
| 170 *found_exponent = cached_power.decimal_exponent; | |
| 171 ASSERT(*found_exponent <= requested_exponent); | |
| 172 ASSERT(requested_exponent < *found_exponent + kDecimalExponentDistance); | |
| 173 } | |
| 174 | |
| 175 } // namespace double_conversion |
