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 explicit Double(double d) : d_(d) {} 27 explicit 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 IsNormal() const { return (u_ & kExponentMask) != 0 || Significand() == 0; } 44 bool IsZero() const { return (u_ & (kExponentMask | kSignificandMask)) == 0; } 45 46 uint64_t IntegerSignificand() const { return IsNormal() ? Significand() | kHiddenBit : Significand(); } 47 int IntegerExponent() const { return (IsNormal() ? Exponent() : kDenormalExponent) - kSignificandSize; } 48 uint64_t ToBias() const { return (u_ & kSignMask) ? ~u_ + 1 : u_ | kSignMask; } 49 50 static unsigned EffectiveSignificandSize(int order) { 51 if (order >= -1021) 52 return 53; 53 else if (order <= -1074) 54 return 0; 55 else 56 return (unsigned)order + 1074; 57 } 58 59 private: 60 static const int kSignificandSize = 52; 61 static const int kExponentBias = 0x3FF; 62 static const int kDenormalExponent = 1 - kExponentBias; 63 static const uint64_t kSignMask = RAPIDJSON_UINT64_C2(0x80000000, 0x00000000); 64 static const uint64_t kExponentMask = RAPIDJSON_UINT64_C2(0x7FF00000, 0x00000000); 65 static const uint64_t kSignificandMask = RAPIDJSON_UINT64_C2(0x000FFFFF, 0xFFFFFFFF); 66 static const uint64_t kHiddenBit = RAPIDJSON_UINT64_C2(0x00100000, 0x00000000); 67 68 union { 69 double d_; 70 uint64_t u_; 71 }; 72 }; 73 74 } // namespace internal 75 RAPIDJSON_NAMESPACE_END 76 77 #endif // RAPIDJSON_IEEE754_ 78
