text: // Tencent is pleased to support the open source community by making RapidJSON available.
  // 
  // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
  //
  // Licensed under the MIT License (the "License"); you may not use this file except
  // in compliance with the License. You may obtain a copy of the License at
  //
  // http://opensource.org/licenses/MIT
  //
  // Unless required by applicable law or agreed to in writing, software distributed 
  // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
  // CONDITIONS OF ANY KIND, either express or implied. See the License for the 
  // specific language governing permissions and limitations under the License.
  
  #ifndef CEREAL_RAPIDJSON_IEEE754_
  #define CEREAL_RAPIDJSON_IEEE754_
  
  #include "../rapidjson.h"
  
  CEREAL_RAPIDJSON_NAMESPACE_BEGIN
  namespace internal {
  
  class Double {
  public:
      Double() {}
      Double(double d) : d_(d) {}
      Double(uint64_t u) : u_(u) {}
  
      double Value() const { return d_; }
      uint64_t Uint64Value() const { return u_; }
  
      double NextPositiveDouble() const {
          CEREAL_RAPIDJSON_ASSERT(!Sign());
          return Double(u_ + 1).Value();
      }
  
      bool Sign() const { return (u_ & kSignMask) != 0; }
      uint64_t Significand() const { return u_ & kSignificandMask; }
      int Exponent() const { return static_cast<int>(((u_ & kExponentMask) >> kSignificandSize) - kExponentBias); }
  
      bool IsNan() const { return (u_ & kExponentMask) == kExponentMask && Significand() != 0; }
      bool IsInf() const { return (u_ & kExponentMask) == kExponentMask && Significand() == 0; }
      bool IsNanOrInf() const { return (u_ & kExponentMask) == kExponentMask; }
      bool IsNormal() const { return (u_ & kExponentMask) != 0 || Significand() == 0; }
      bool IsZero() const { return (u_ & (kExponentMask | kSignificandMask)) == 0; }
  
      uint64_t IntegerSignificand() const { return IsNormal() ? Significand() | kHiddenBit : Significand(); }
      int IntegerExponent() const { return (IsNormal() ? Exponent() : kDenormalExponent) - kSignificandSize; }
      uint64_t ToBias() const { return (u_ & kSignMask) ? ~u_ + 1 : u_ | kSignMask; }
  
      static unsigned EffectiveSignificandSize(int order) {
          if (order >= -1021)
              return 53;
          else if (order <= -1074)
              return 0;
          else
              return static_cast<unsigned>(order) + 1074;
      }
  
  private:
      static const int kSignificandSize = 52;
      static const int kExponentBias = 0x3FF;
      static const int kDenormalExponent = 1 - kExponentBias;
      static const uint64_t kSignMask = CEREAL_RAPIDJSON_UINT64_C2(0x80000000, 0x00000000);
      static const uint64_t kExponentMask = CEREAL_RAPIDJSON_UINT64_C2(0x7FF00000, 0x00000000);
      static const uint64_t kSignificandMask = CEREAL_RAPIDJSON_UINT64_C2(0x000FFFFF, 0xFFFFFFFF);
      static const uint64_t kHiddenBit = CEREAL_RAPIDJSON_UINT64_C2(0x00100000, 0x00000000);
  
      union {
          double d_;
          uint64_t u_;
      };
  };
  
  } // namespace internal
  CEREAL_RAPIDJSON_NAMESPACE_END
  
  #endif // CEREAL_RAPIDJSON_IEEE754_
  