LCOV - code coverage report
Current view: directory - js/src/v8-dtoa - diy-fp.cc (source / functions) Found Hit Coverage
Test: app.info Lines: 16 16 100.0 %
Date: 2012-06-02 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                 : #include "v8.h"
      29                 : 
      30                 : #include "diy-fp.h"
      31                 : 
      32                 : namespace v8 {
      33                 : namespace internal {
      34                 : 
      35          772005 : void DiyFp::Multiply(const DiyFp& other) {
      36                 :   // Simply "emulates" a 128 bit multiplication.
      37                 :   // However: the resulting number only contains 64 bits. The least
      38                 :   // significant 64 bits are only used for rounding the most significant 64
      39                 :   // bits.
      40          772005 :   const uint64_t kM32 = 0xFFFFFFFFu;
      41          772005 :   uint64_t a = f_ >> 32;
      42          772005 :   uint64_t b = f_ & kM32;
      43          772005 :   uint64_t c = other.f_ >> 32;
      44          772005 :   uint64_t d = other.f_ & kM32;
      45          772005 :   uint64_t ac = a * c;
      46          772005 :   uint64_t bc = b * c;
      47          772005 :   uint64_t ad = a * d;
      48          772005 :   uint64_t bd = b * d;
      49          772005 :   uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32);
      50                 :   // By adding 1U << 31 to tmp we round the final result.
      51                 :   // Halfway cases will be round up.
      52          772005 :   tmp += 1U << 31;
      53          772005 :   uint64_t result_f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
      54          772005 :   e_ += other.e_ + 64;
      55          772005 :   f_ = result_f;
      56          772005 : }
      57                 : 
      58                 : } }  // namespace v8::internal

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