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: 2017-04-26 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     5275791 : 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     5275791 :   double k = std::ceil((min_exponent + kQ - 1) * kD_1_LOG2_10);
     134             :   int foo = kCachedPowersOffset;
     135             :   int index =
     136     5275791 :       (foo + static_cast<int>(k) - 1) / kDecimalExponentDistance + 1;
     137             :   DCHECK(0 <= index && index < kCachedPowersLength);
     138     5275791 :   CachedPower cached_power = kCachedPowers[index];
     139             :   DCHECK(min_exponent <= cached_power.binary_exponent);
     140             :   DCHECK(cached_power.binary_exponent <= max_exponent);
     141     5275791 :   *decimal_exponent = cached_power.decimal_exponent;
     142     5275791 :   *power = DiyFp(cached_power.significand, cached_power.binary_exponent);
     143     5275791 : }
     144             : 
     145             : 
     146       67435 : void PowersOfTenCache::GetCachedPowerForDecimalExponent(int requested_exponent,
     147             :                                                         DiyFp* power,
     148             :                                                         int* found_exponent) {
     149             :   DCHECK(kMinDecimalExponent <= requested_exponent);
     150             :   DCHECK(requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance);
     151             :   int index =
     152       67435 :       (requested_exponent + kCachedPowersOffset) / kDecimalExponentDistance;
     153       67435 :   CachedPower cached_power = kCachedPowers[index];
     154       67435 :   *power = DiyFp(cached_power.significand, cached_power.binary_exponent);
     155       67435 :   *found_exponent = cached_power.decimal_exponent;
     156             :   DCHECK(*found_exponent <= requested_exponent);
     157             :   DCHECK(requested_exponent < *found_exponent + kDecimalExponentDistance);
     158       67435 : }
     159             : 
     160             : }  // namespace internal
     161             : }  // namespace v8

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