RapidJSON: include/rapidjson/internal/ieee754.h Source File

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.
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 int EffectiveSignificandSize(int order) {
52 if (order >= -1021)
53 return 53;
54 else if (order <= -1074)
55 return 0;
56 else
57 return 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_
RAPIDJSON_ASSERT
#define RAPIDJSON_ASSERT(x)
Assertion.
Definition: rapidjson.h:406
rapidjson::Value
GenericValue< UTF8<> > Value
GenericValue with UTF8 encoding.
Definition: document.h:2192
RAPIDJSON_UINT64_C2
#define RAPIDJSON_UINT64_C2(high32, low32)
Construct a 64-bit literal by a pair of 32-bit integer.
Definition: rapidjson.h:289