LCOV - app.info - js/src/v8-dtoa/cached-powers.h

LCOV - code coverage report
| Current view: | directory - js/src/v8-dtoa - cached-powers.h (source / functions) |  | Found | Hit | Coverage |
| Test: | app.info | Lines: | 31 | 27 | 87.1 %
| Date: | 2012-04-07 | Functions: | 1 | 1 | 100.0 %

           1                 : // Copyright 2010 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                 : #ifndef V8_CACHED_POWERS_H_
          29                 : #define V8_CACHED_POWERS_H_
          30                 :
          31                 : #include "diy-fp.h"
          32                 :
          33                 : namespace v8 {
          34                 : namespace internal {
          35                 :
          36                 : struct CachedPower {
          37                 :   uint64_t significand;
          38                 :   int16_t binary_exponent;
          39                 :   int16_t decimal_exponent;
          40                 : };
          41                 :
          42                 : // The following defines implement the interface between this file and the
          43                 : // generated 'powers_ten.h'.
          44                 : // GRISU_CACHE_NAME(1) contains all possible cached powers.
          45                 : // GRISU_CACHE_NAME(i) contains GRISU_CACHE_NAME(1) where only every 'i'th
          46                 : // element is kept. More formally GRISU_CACHE_NAME(i) contains the elements j*i
          47                 : // with 0 <= j < k with k such that j*k < the size of GRISU_CACHE_NAME(1).
          48                 : // The higher 'i' is the fewer elements we use.
          49                 : // Given that there are less elements, the exponent-distance between two
          50                 : // elements in the cache grows. The variable GRISU_CACHE_MAX_DISTANCE(i) stores
          51                 : // the maximum distance between two elements.
          52                 : #define GRISU_CACHE_STRUCT CachedPower
          53                 : #define GRISU_CACHE_NAME(i) kCachedPowers##i
          54                 : #define GRISU_CACHE_MAX_DISTANCE(i) kCachedPowersMaxDistance##i
          55                 : #define GRISU_CACHE_OFFSET kCachedPowerOffset
          56                 : #define GRISU_UINT64_C V8_2PART_UINT64_C
          57                 : // The following include imports the precompiled cached powers.
          58                 : #include "powers-ten.h"  // NOLINT
          59                 :
          60                 : static const double kD_1_LOG2_10 = 0.30102999566398114;  //  1 / lg(10)
          61                 :
          62                 : // We can't use a function since we reference variables depending on the 'i'.
          63                 : // This way the compiler is able to see at compile time that only one
          64                 : // cache-array variable is used and thus can remove all the others.
          65                 : #define COMPUTE_FOR_CACHE(i) \
          66                 :   if (!found && (gamma - alpha + 1 >= GRISU_CACHE_MAX_DISTANCE(i))) {   \
          67                 :     int kQ = DiyFp::kSignificandSize;                                   \
          68                 :     double k = ceiling((alpha - e + kQ - 1) * kD_1_LOG2_10);            \
          69                 :     int index = (GRISU_CACHE_OFFSET + static_cast<int>(k) - 1) / i + 1; \
          70                 :     cached_power = GRISU_CACHE_NAME(i)[index];                          \
          71                 :     found = true;                                                       \
          72                 :   }                                                                     \
          73                 :
          74          213007 : static void GetCachedPower(int e, int alpha, int gamma, int* mk, DiyFp* c_mk) {
          75                 :   // The following if statement should be optimized by the compiler so that only
          76                 :   // one array is referenced and the others are not included in the object file.
          77          213007 :   bool found = false;
          78                 :   CachedPower cached_power;
          79          213007 :   COMPUTE_FOR_CACHE(20);
          80          213007 :   COMPUTE_FOR_CACHE(19);
          81          213007 :   COMPUTE_FOR_CACHE(18);
          82          213007 :   COMPUTE_FOR_CACHE(17);
          83          213007 :   COMPUTE_FOR_CACHE(16);
          84          213007 :   COMPUTE_FOR_CACHE(15);
          85          213007 :   COMPUTE_FOR_CACHE(14);
          86          213007 :   COMPUTE_FOR_CACHE(13);
          87          213007 :   COMPUTE_FOR_CACHE(12);
          88          213007 :   COMPUTE_FOR_CACHE(11);
          89          213007 :   COMPUTE_FOR_CACHE(10);
          90          213007 :   COMPUTE_FOR_CACHE(9);
          91          213007 :   COMPUTE_FOR_CACHE(8);
          92          213007 :   COMPUTE_FOR_CACHE(7);
          93          213007 :   COMPUTE_FOR_CACHE(6);
          94          213007 :   COMPUTE_FOR_CACHE(5);
          95          213007 :   COMPUTE_FOR_CACHE(4);
          96          213007 :   COMPUTE_FOR_CACHE(3);
          97          213007 :   COMPUTE_FOR_CACHE(2);
          98          213007 :   COMPUTE_FOR_CACHE(1);
          99          213007 :   if (!found) {
         100               0 :     UNIMPLEMENTED();
         101                 :     // Silence compiler warnings.
         102               0 :     cached_power.significand = 0;
         103               0 :     cached_power.binary_exponent = 0;
         104               0 :     cached_power.decimal_exponent = 0;
         105                 :   }
         106          213007 :   *c_mk = DiyFp(cached_power.significand, cached_power.binary_exponent);
         107          213007 :   *mk = cached_power.decimal_exponent;
         108          213007 :   ASSERT((alpha <= c_mk->e() + e) && (c_mk->e() + e <= gamma));
         109          213007 : }
         110                 : #undef GRISU_REDUCTION
         111                 : #undef GRISU_CACHE_STRUCT
         112                 : #undef GRISU_CACHE_NAME
         113                 : #undef GRISU_CACHE_MAX_DISTANCE
         114                 : #undef GRISU_CACHE_OFFSET
         115                 : #undef GRISU_UINT64_C
         116                 :
         117                 : } }  // namespace v8::internal
         118                 :
         119                 : #endif  // V8_CACHED_POWERS_H_

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