ieee754.h Source File

ieee754.h Source File#

Composable Kernel: ieee754.h Source File
// 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.
//
// 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 RAPIDJSON_IEEE754_
#define RAPIDJSON_IEEE754_
 
#include "../rapidjson.h"
 
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
    {
        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 int EffectiveSignificandSize(int order)
    {
        if(order >= -1021)
            return 53;
        else if(order <= -1074)
            return 0;
        else
            return order + 1074;
    }
 
    private:
    static const int kSignificandSize      = 52;
    static const int kExponentBias         = 0x3FF;
    static const int kDenormalExponent     = 1 - kExponentBias;
    static const uint64_t kSignMask        = RAPIDJSON_UINT64_C2(0x80000000, 0x00000000);
    static const uint64_t kExponentMask    = RAPIDJSON_UINT64_C2(0x7FF00000, 0x00000000);
    static const uint64_t kSignificandMask = RAPIDJSON_UINT64_C2(0x000FFFFF, 0xFFFFFFFF);
    static const uint64_t kHiddenBit       = RAPIDJSON_UINT64_C2(0x00100000, 0x00000000);
 
    union
    {
        double d_;
        uint64_t u_;
    };
};
 
} // namespace internal
RAPIDJSON_NAMESPACE_END
 
#endif // RAPIDJSON_IEEE754_