LCOV - code coverage report
Current view: top level - src - cached-powers.cc (source / functions) Hit Total Coverage
Test: app.info Lines: 13 13 100.0 %
Date: 2019-03-21 Functions: 2 2 100.0 %

          Line data    Source code
       1             : // Copyright 2011 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #include "src/cached-powers.h"
       6             : 
       7             : #include <limits.h>
       8             : #include <stdarg.h>
       9             : #include <stdint.h>
      10             : #include <cmath>
      11             : 
      12             : #include "src/base/logging.h"
      13             : #include "src/globals.h"
      14             : 
      15             : namespace v8 {
      16             : namespace internal {
      17             : 
      18             : struct CachedPower {
      19             :   uint64_t significand;
      20             :   int16_t binary_exponent;
      21             :   int16_t decimal_exponent;
      22             : };
      23             : 
      24             : static const CachedPower kCachedPowers[] = {
      25             :     {V8_2PART_UINT64_C(0xFA8FD5A0, 081C0288), -1220, -348},
      26             :     {V8_2PART_UINT64_C(0xBAAEE17F, A23EBF76), -1193, -340},
      27             :     {V8_2PART_UINT64_C(0x8B16FB20, 3055AC76), -1166, -332},
      28             :     {V8_2PART_UINT64_C(0xCF42894A, 5DCE35EA), -1140, -324},
      29             :     {V8_2PART_UINT64_C(0x9A6BB0AA, 55653B2D), -1113, -316},
      30             :     {V8_2PART_UINT64_C(0xE61ACF03, 3D1A45DF), -1087, -308},
      31             :     {V8_2PART_UINT64_C(0xAB70FE17, C79AC6CA), -1060, -300},
      32             :     {V8_2PART_UINT64_C(0xFF77B1FC, BEBCDC4F), -1034, -292},
      33             :     {V8_2PART_UINT64_C(0xBE5691EF, 416BD60C), -1007, -284},
      34             :     {V8_2PART_UINT64_C(0x8DD01FAD, 907FFC3C), -980, -276},
      35             :     {V8_2PART_UINT64_C(0xD3515C28, 31559A83), -954, -268},
      36             :     {V8_2PART_UINT64_C(0x9D71AC8F, ADA6C9B5), -927, -260},
      37             :     {V8_2PART_UINT64_C(0xEA9C2277, 23EE8BCB), -901, -252},
      38             :     {V8_2PART_UINT64_C(0xAECC4991, 4078536D), -874, -244},
      39             :     {V8_2PART_UINT64_C(0x823C1279, 5DB6CE57), -847, -236},
      40             :     {V8_2PART_UINT64_C(0xC2109436, 4DFB5637), -821, -228},
      41             :     {V8_2PART_UINT64_C(0x9096EA6F, 3848984F), -794, -220},
      42             :     {V8_2PART_UINT64_C(0xD77485CB, 25823AC7), -768, -212},
      43             :     {V8_2PART_UINT64_C(0xA086CFCD, 97BF97F4), -741, -204},
      44             :     {V8_2PART_UINT64_C(0xEF340A98, 172AACE5), -715, -196},
      45             :     {V8_2PART_UINT64_C(0xB23867FB, 2A35B28E), -688, -188},
      46             :     {V8_2PART_UINT64_C(0x84C8D4DF, D2C63F3B), -661, -180},
      47             :     {V8_2PART_UINT64_C(0xC5DD4427, 1AD3CDBA), -635, -172},
      48             :     {V8_2PART_UINT64_C(0x936B9FCE, BB25C996), -608, -164},
      49             :     {V8_2PART_UINT64_C(0xDBAC6C24, 7D62A584), -582, -156},
      50             :     {V8_2PART_UINT64_C(0xA3AB6658, 0D5FDAF6), -555, -148},
      51             :     {V8_2PART_UINT64_C(0xF3E2F893, DEC3F126), -529, -140},
      52             :     {V8_2PART_UINT64_C(0xB5B5ADA8, AAFF80B8), -502, -132},
      53             :     {V8_2PART_UINT64_C(0x87625F05, 6C7C4A8B), -475, -124},
      54             :     {V8_2PART_UINT64_C(0xC9BCFF60, 34C13053), -449, -116},
      55             :     {V8_2PART_UINT64_C(0x964E858C, 91BA2655), -422, -108},
      56             :     {V8_2PART_UINT64_C(0xDFF97724, 70297EBD), -396, -100},
      57             :     {V8_2PART_UINT64_C(0xA6DFBD9F, B8E5B88F), -369, -92},
      58             :     {V8_2PART_UINT64_C(0xF8A95FCF, 88747D94), -343, -84},
      59             :     {V8_2PART_UINT64_C(0xB9447093, 8FA89BCF), -316, -76},
      60             :     {V8_2PART_UINT64_C(0x8A08F0F8, BF0F156B), -289, -68},
      61             :     {V8_2PART_UINT64_C(0xCDB02555, 653131B6), -263, -60},
      62             :     {V8_2PART_UINT64_C(0x993FE2C6, D07B7FAC), -236, -52},
      63             :     {V8_2PART_UINT64_C(0xE45C10C4, 2A2B3B06), -210, -44},
      64             :     {V8_2PART_UINT64_C(0xAA242499, 697392D3), -183, -36},
      65             :     {V8_2PART_UINT64_C(0xFD87B5F2, 8300CA0E), -157, -28},
      66             :     {V8_2PART_UINT64_C(0xBCE50864, 92111AEB), -130, -20},
      67             :     {V8_2PART_UINT64_C(0x8CBCCC09, 6F5088CC), -103, -12},
      68             :     {V8_2PART_UINT64_C(0xD1B71758, E219652C), -77, -4},
      69             :     {V8_2PART_UINT64_C(0x9C400000, 00000000), -50, 4},
      70             :     {V8_2PART_UINT64_C(0xE8D4A510, 00000000), -24, 12},
      71             :     {V8_2PART_UINT64_C(0xAD78EBC5, AC620000), 3, 20},
      72             :     {V8_2PART_UINT64_C(0x813F3978, F8940984), 30, 28},
      73             :     {V8_2PART_UINT64_C(0xC097CE7B, C90715B3), 56, 36},
      74             :     {V8_2PART_UINT64_C(0x8F7E32CE, 7BEA5C70), 83, 44},
      75             :     {V8_2PART_UINT64_C(0xD5D238A4, ABE98068), 109, 52},
      76             :     {V8_2PART_UINT64_C(0x9F4F2726, 179A2245), 136, 60},
      77             :     {V8_2PART_UINT64_C(0xED63A231, D4C4FB27), 162, 68},
      78             :     {V8_2PART_UINT64_C(0xB0DE6538, 8CC8ADA8), 189, 76},
      79             :     {V8_2PART_UINT64_C(0x83C7088E, 1AAB65DB), 216, 84},
      80             :     {V8_2PART_UINT64_C(0xC45D1DF9, 42711D9A), 242, 92},
      81             :     {V8_2PART_UINT64_C(0x924D692C, A61BE758), 269, 100},
      82             :     {V8_2PART_UINT64_C(0xDA01EE64, 1A708DEA), 295, 108},
      83             :     {V8_2PART_UINT64_C(0xA26DA399, 9AEF774A), 322, 116},
      84             :     {V8_2PART_UINT64_C(0xF209787B, B47D6B85), 348, 124},
      85             :     {V8_2PART_UINT64_C(0xB454E4A1, 79DD1877), 375, 132},
      86             :     {V8_2PART_UINT64_C(0x865B8692, 5B9BC5C2), 402, 140},
      87             :     {V8_2PART_UINT64_C(0xC83553C5, C8965D3D), 428, 148},
      88             :     {V8_2PART_UINT64_C(0x952AB45C, FA97A0B3), 455, 156},
      89             :     {V8_2PART_UINT64_C(0xDE469FBD, 99A05FE3), 481, 164},
      90             :     {V8_2PART_UINT64_C(0xA59BC234, DB398C25), 508, 172},
      91             :     {V8_2PART_UINT64_C(0xF6C69A72, A3989F5C), 534, 180},
      92             :     {V8_2PART_UINT64_C(0xB7DCBF53, 54E9BECE), 561, 188},
      93             :     {V8_2PART_UINT64_C(0x88FCF317, F22241E2), 588, 196},
      94             :     {V8_2PART_UINT64_C(0xCC20CE9B, D35C78A5), 614, 204},
      95             :     {V8_2PART_UINT64_C(0x98165AF3, 7B2153DF), 641, 212},
      96             :     {V8_2PART_UINT64_C(0xE2A0B5DC, 971F303A), 667, 220},
      97             :     {V8_2PART_UINT64_C(0xA8D9D153, 5CE3B396), 694, 228},
      98             :     {V8_2PART_UINT64_C(0xFB9B7CD9, A4A7443C), 720, 236},
      99             :     {V8_2PART_UINT64_C(0xBB764C4C, A7A44410), 747, 244},
     100             :     {V8_2PART_UINT64_C(0x8BAB8EEF, B6409C1A), 774, 252},
     101             :     {V8_2PART_UINT64_C(0xD01FEF10, A657842C), 800, 260},
     102             :     {V8_2PART_UINT64_C(0x9B10A4E5, E9913129), 827, 268},
     103             :     {V8_2PART_UINT64_C(0xE7109BFB, A19C0C9D), 853, 276},
     104             :     {V8_2PART_UINT64_C(0xAC2820D9, 623BF429), 880, 284},
     105             :     {V8_2PART_UINT64_C(0x80444B5E, 7AA7CF85), 907, 292},
     106             :     {V8_2PART_UINT64_C(0xBF21E440, 03ACDD2D), 933, 300},
     107             :     {V8_2PART_UINT64_C(0x8E679C2F, 5E44FF8F), 960, 308},
     108             :     {V8_2PART_UINT64_C(0xD433179D, 9C8CB841), 986, 316},
     109             :     {V8_2PART_UINT64_C(0x9E19DB92, B4E31BA9), 1013, 324},
     110             :     {V8_2PART_UINT64_C(0xEB96BF6E, BADF77D9), 1039, 332},
     111             :     {V8_2PART_UINT64_C(0xAF87023B, 9BF0EE6B), 1066, 340},
     112             : };
     113             : 
     114             : #ifdef DEBUG
     115             : static const int kCachedPowersLength = arraysize(kCachedPowers);
     116             : #endif
     117             : 
     118             : static const int kCachedPowersOffset = 348;  // -1 * the first decimal_exponent.
     119             : static const double kD_1_LOG2_10 = 0.30102999566398114;  //  1 / lg(10)
     120             : // Difference between the decimal exponents in the table above.
     121             : const int PowersOfTenCache::kDecimalExponentDistance = 8;
     122             : const int PowersOfTenCache::kMinDecimalExponent = -348;
     123             : const int PowersOfTenCache::kMaxDecimalExponent = 340;
     124             : 
     125     3136851 : void PowersOfTenCache::GetCachedPowerForBinaryExponentRange(
     126             :     int min_exponent,
     127             :     int max_exponent,
     128             :     DiyFp* power,
     129             :     int* decimal_exponent) {
     130             :   int kQ = DiyFp::kSignificandSize;
     131             :   // Some platforms return incorrect sign on 0 result. We can ignore that here,
     132             :   // which means we can avoid depending on platform.h.
     133     3136851 :   double k = std::ceil((min_exponent + kQ - 1) * kD_1_LOG2_10);
     134             :   int foo = kCachedPowersOffset;
     135             :   int index =
     136     3136851 :       (foo + static_cast<int>(k) - 1) / kDecimalExponentDistance + 1;
     137             :   DCHECK(0 <= index && index < kCachedPowersLength);
     138     3136851 :   CachedPower cached_power = kCachedPowers[index];
     139             :   DCHECK(min_exponent <= cached_power.binary_exponent);
     140             :   DCHECK(cached_power.binary_exponent <= max_exponent);
     141     3136851 :   *decimal_exponent = cached_power.decimal_exponent;
     142     3136851 :   *power = DiyFp(cached_power.significand, cached_power.binary_exponent);
     143     3136851 : }
     144             : 
     145             : 
     146       45473 : void PowersOfTenCache::GetCachedPowerForDecimalExponent(int requested_exponent,
     147             :                                                         DiyFp* power,
     148             :                                                         int* found_exponent) {
     149             :   DCHECK_LE(kMinDecimalExponent, requested_exponent);
     150             :   DCHECK(requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance);
     151             :   int index =
     152       45473 :       (requested_exponent + kCachedPowersOffset) / kDecimalExponentDistance;
     153       45473 :   CachedPower cached_power = kCachedPowers[index];
     154       45473 :   *power = DiyFp(cached_power.significand, cached_power.binary_exponent);
     155       45473 :   *found_exponent = cached_power.decimal_exponent;
     156             :   DCHECK(*found_exponent <= requested_exponent);
     157             :   DCHECK(requested_exponent < *found_exponent + kDecimalExponentDistance);
     158       45473 : }
     159             : 
     160             : }  // namespace internal
     161             : }  // namespace v8

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