// 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_