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mfbt/double-conversion/cached-powers.cc@6474c204b198 (annotated)

mfbt/double-conversion/cached-powers.cc

Wed, 31 Dec 2014 06:09:35 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Wed, 31 Dec 2014 06:09:35 +0100
changeset 0
6474c204b198
permissions
-rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

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

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