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:
Double()25     Double() {}
Double(double d)26     Double(double d) : d_(d) {}
Double(uint64_t u)27     Double(uint64_t u) : u_(u) {}
28 
Value()29     double Value() const { return d_; }
Uint64Value()30     uint64_t Uint64Value() const { return u_; }
31 
NextPositiveDouble()32     double NextPositiveDouble() const {
33         RAPIDJSON_ASSERT(!Sign());
34         return Double(u_ + 1).Value();
35     }
36 
Sign()37     bool Sign() const { return (u_ & kSignMask) != 0; }
Significand()38     uint64_t Significand() const { return u_ & kSignificandMask; }
Exponent()39     int Exponent() const { return static_cast<int>(((u_ & kExponentMask) >> kSignificandSize) - kExponentBias); }
40 
IsNan()41     bool IsNan() const { return (u_ & kExponentMask) == kExponentMask && Significand() != 0; }
IsInf()42     bool IsInf() const { return (u_ & kExponentMask) == kExponentMask && Significand() == 0; }
IsNormal()43     bool IsNormal() const { return (u_ & kExponentMask) != 0 || Significand() == 0; }
IsZero()44     bool IsZero() const { return (u_ & (kExponentMask | kSignificandMask)) == 0; }
45 
IntegerSignificand()46     uint64_t IntegerSignificand() const { return IsNormal() ? Significand() | kHiddenBit : Significand(); }
IntegerExponent()47     int IntegerExponent() const { return (IsNormal() ? Exponent() : kDenormalExponent) - kSignificandSize; }
ToBias()48     uint64_t ToBias() const { return (u_ & kSignMask) ? ~u_ + 1 : u_ | kSignMask; }
49 
EffectiveSignificandSize(int order)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