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      1 //  2018 and later: Unicode, Inc. and others.
      2 // License & terms of use: http://www.unicode.org/copyright.html
      3 //
      4 // From the double-conversion library. Original license:
      5 //
      6 // Copyright 2010 the V8 project authors. All rights reserved.
      7 // Redistribution and use in source and binary forms, with or without
      8 // modification, are permitted provided that the following conditions are
      9 // met:
     10 //
     11 //     * Redistributions of source code must retain the above copyright
     12 //       notice, this list of conditions and the following disclaimer.
     13 //     * Redistributions in binary form must reproduce the above
     14 //       copyright notice, this list of conditions and the following
     15 //       disclaimer in the documentation and/or other materials provided
     16 //       with the distribution.
     17 //     * Neither the name of Google Inc. nor the names of its
     18 //       contributors may be used to endorse or promote products derived
     19 //       from this software without specific prior written permission.
     20 //
     21 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     22 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     23 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     24 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     25 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     26 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     27 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     28 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     29 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     30 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     31 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     32 
     33 // ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
     34 #include "unicode/utypes.h"
     35 #if !UCONFIG_NO_FORMATTING
     36 
     37 #ifndef DOUBLE_CONVERSION_DIY_FP_H_
     38 #define DOUBLE_CONVERSION_DIY_FP_H_
     39 
     40 // ICU PATCH: Customize header file paths for ICU.
     41 
     42 #include "double-conversion-utils.h"
     43 
     44 // ICU PATCH: Wrap in ICU namespace
     45 U_NAMESPACE_BEGIN
     46 
     47 namespace double_conversion {
     48 
     49 // This "Do It Yourself Floating Point" class implements a floating-point number
     50 // with a uint64 significand and an int exponent. Normalized DiyFp numbers will
     51 // have the most significant bit of the significand set.
     52 // Multiplication and Subtraction do not normalize their results.
     53 // DiyFp are not designed to contain special doubles (NaN and Infinity).
     54 class DiyFp {
     55  public:
     56   static const int kSignificandSize = 64;
     57 
     58   DiyFp() : f_(0), e_(0) {}
     59   DiyFp(uint64_t significand, int exponent) : f_(significand), e_(exponent) {}
     60 
     61   // this = this - other.
     62   // The exponents of both numbers must be the same and the significand of this
     63   // must be bigger than the significand of other.
     64   // The result will not be normalized.
     65   void Subtract(const DiyFp& other) {
     66     ASSERT(e_ == other.e_);
     67     ASSERT(f_ >= other.f_);
     68     f_ -= other.f_;
     69   }
     70 
     71   // Returns a - b.
     72   // The exponents of both numbers must be the same and this must be bigger
     73   // than other. The result will not be normalized.
     74   static DiyFp Minus(const DiyFp& a, const DiyFp& b) {
     75     DiyFp result = a;
     76     result.Subtract(b);
     77     return result;
     78   }
     79 
     80 
     81   // this = this * other.
     82   void Multiply(const DiyFp& other);
     83 
     84   // returns a * b;
     85   static DiyFp Times(const DiyFp& a, const DiyFp& b) {
     86     DiyFp result = a;
     87     result.Multiply(b);
     88     return result;
     89   }
     90 
     91   void Normalize() {
     92     ASSERT(f_ != 0);
     93     uint64_t significand = f_;
     94     int exponent = e_;
     95 
     96     // This method is mainly called for normalizing boundaries. In general
     97     // boundaries need to be shifted by 10 bits. We thus optimize for this case.
     98     const uint64_t k10MSBits = UINT64_2PART_C(0xFFC00000, 00000000);
     99     while ((significand & k10MSBits) == 0) {
    100       significand <<= 10;
    101       exponent -= 10;
    102     }
    103     while ((significand & kUint64MSB) == 0) {
    104       significand <<= 1;
    105       exponent--;
    106     }
    107     f_ = significand;
    108     e_ = exponent;
    109   }
    110 
    111   static DiyFp Normalize(const DiyFp& a) {
    112     DiyFp result = a;
    113     result.Normalize();
    114     return result;
    115   }
    116 
    117   uint64_t f() const { return f_; }
    118   int e() const { return e_; }
    119 
    120   void set_f(uint64_t new_value) { f_ = new_value; }
    121   void set_e(int new_value) { e_ = new_value; }
    122 
    123  private:
    124   static const uint64_t kUint64MSB = UINT64_2PART_C(0x80000000, 00000000);
    125 
    126   uint64_t f_;
    127   int e_;
    128 };
    129 
    130 }  // namespace double_conversion
    131 
    132 // ICU PATCH: Close ICU namespace
    133 U_NAMESPACE_END
    134 
    135 #endif  // DOUBLE_CONVERSION_DIY_FP_H_
    136 #endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING
    137