ceph/src/rapidjson/include/rapidjson/internal/ieee754.h

   1 // Tencent is pleased to support the open source community by making RapidJSON available.
   2 //
   3 // Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
   4 //
   5 // Licensed under the MIT License (the "License"); you may not use this file except
   6 // in compliance with the License. You may obtain a copy of the License at
   7 //
   8 // http://opensource.org/licenses/MIT
   9 //
  10 // Unless required by applicable law or agreed to in writing, software distributed
  11 // under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
  12 // CONDITIONS OF ANY KIND, either express or implied. See the License for the
  13 // specific language governing permissions and limitations under the License.
  14
  15 #ifndef RAPIDJSON_IEEE754_
  16 #define RAPIDJSON_IEEE754_
  17
  18 #include "../rapidjson.h"
  19
  20 RAPIDJSON_NAMESPACE_BEGIN
  21 namespace internal {
  22
  23 class Double {
  24 public:
  25     Double() {}
  26     Double(double d) : d_(d) {}
  27     Double(uint64_t u) : u_(u) {}
  28
  29     double Value() const { return d_; }
  30     uint64_t Uint64Value() const { return u_; }
  31
  32     double NextPositiveDouble() const {
  33         RAPIDJSON_ASSERT(!Sign());
  34         return Double(u_ + 1).Value();
  35     }
  36
  37     bool Sign() const { return (u_ & kSignMask) != 0; }
  38     uint64_t Significand() const { return u_ & kSignificandMask; }
  39     int Exponent() const { return static_cast<int>(((u_ & kExponentMask) >> kSignificandSize) - kExponentBias); }
  40
  41     bool IsNan() const { return (u_ & kExponentMask) == kExponentMask && Significand() != 0; }
  42     bool IsInf() const { return (u_ & kExponentMask) == kExponentMask && Significand() == 0; }
  43     bool IsNanOrInf() const { return (u_ & kExponentMask) == kExponentMask; }
  44     bool IsNormal() const { return (u_ & kExponentMask) != 0 || Significand() == 0; }
  45     bool IsZero() const { return (u_ & (kExponentMask | kSignificandMask)) == 0; }
  46
  47     uint64_t IntegerSignificand() const { return IsNormal() ? Significand() | kHiddenBit : Significand(); }
  48     int IntegerExponent() const { return (IsNormal() ? Exponent() : kDenormalExponent) - kSignificandSize; }
  49     uint64_t ToBias() const { return (u_ & kSignMask) ? ~u_ + 1 : u_ | kSignMask; }
  50
  51     static unsigned EffectiveSignificandSize(int order) {
  52         if (order >= -1021)
  53             return 53;
  54         else if (order <= -1074)
  55             return 0;
  56         else
  57             return static_cast<unsigned>(order) + 1074;
  58     }
  59
  60 private:
  61     static const int kSignificandSize = 52;
  62     static const int kExponentBias = 0x3FF;
  63     static const int kDenormalExponent = 1 - kExponentBias;
  64     static const uint64_t kSignMask = RAPIDJSON_UINT64_C2(0x80000000, 0x00000000);
  65     static const uint64_t kExponentMask = RAPIDJSON_UINT64_C2(0x7FF00000, 0x00000000);
  66     static const uint64_t kSignificandMask = RAPIDJSON_UINT64_C2(0x000FFFFF, 0xFFFFFFFF);
  67     static const uint64_t kHiddenBit = RAPIDJSON_UINT64_C2(0x00100000, 0x00000000);
  68
  69     union {
  70         double d_;
  71         uint64_t u_;
  72     };
  73 };
  74
  75 } // namespace internal
  76 RAPIDJSON_NAMESPACE_END
  77
  78 #endif // RAPIDJSON_IEEE754_