kun yu 77e1ddd81b branch-0.4.0
Former-commit-id: a4df63653202df32d0b983de27f5c969905d17ac
2019-07-30 10:23:34 +08:00

176 lines
7.0 KiB
C++

// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// 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.
#pragma once
#include <array>
#include <cstdint>
#include <limits>
#include <string>
#include <type_traits>
#include "arrow/util/macros.h"
#include "arrow/util/type_traits.h"
#include "arrow/util/visibility.h"
namespace arrow {
enum class DecimalStatus {
kSuccess,
kDivideByZero,
kOverflow,
kRescaleDataLoss,
};
/// Represents a signed 128-bit integer in two's complement.
///
/// This class is also compiled into LLVM IR - so, it should not have cpp references like
/// streams and boost.
class ARROW_EXPORT BasicDecimal128 {
public:
/// \brief Create a BasicDecimal128 from the two's complement representation.
constexpr BasicDecimal128(int64_t high, uint64_t low) noexcept
: low_bits_(low), high_bits_(high) {}
/// \brief Empty constructor creates a BasicDecimal128 with a value of 0.
constexpr BasicDecimal128() noexcept : BasicDecimal128(0, 0) {}
/// \brief Convert any integer value into a BasicDecimal128.
template <typename T,
typename = typename std::enable_if<std::is_integral<T>::value, T>::type>
constexpr BasicDecimal128(T value) noexcept
: BasicDecimal128(static_cast<int64_t>(value) >= 0 ? 0 : -1,
static_cast<uint64_t>(value)) {}
/// \brief Create a BasicDecimal128 from an array of bytes. Bytes are assumed to be in
/// little-endian byte order.
explicit BasicDecimal128(const uint8_t* bytes);
/// \brief Negate the current value (in-place)
BasicDecimal128& Negate();
/// \brief Absolute value (in-place)
BasicDecimal128& Abs();
/// \brief Absolute value
static BasicDecimal128 Abs(const BasicDecimal128& left);
/// \brief Add a number to this one. The result is truncated to 128 bits.
BasicDecimal128& operator+=(const BasicDecimal128& right);
/// \brief Subtract a number from this one. The result is truncated to 128 bits.
BasicDecimal128& operator-=(const BasicDecimal128& right);
/// \brief Multiply this number by another number. The result is truncated to 128 bits.
BasicDecimal128& operator*=(const BasicDecimal128& right);
/// Divide this number by right and return the result.
///
/// This operation is not destructive.
/// The answer rounds to zero. Signs work like:
/// 21 / 5 -> 4, 1
/// -21 / 5 -> -4, -1
/// 21 / -5 -> -4, 1
/// -21 / -5 -> 4, -1
/// \param[in] divisor the number to divide by
/// \param[out] result the quotient
/// \param[out] remainder the remainder after the division
DecimalStatus Divide(const BasicDecimal128& divisor, BasicDecimal128* result,
BasicDecimal128* remainder) const;
/// \brief In-place division.
BasicDecimal128& operator/=(const BasicDecimal128& right);
/// \brief Bitwise "or" between two BasicDecimal128.
BasicDecimal128& operator|=(const BasicDecimal128& right);
/// \brief Bitwise "and" between two BasicDecimal128.
BasicDecimal128& operator&=(const BasicDecimal128& right);
/// \brief Shift left by the given number of bits.
BasicDecimal128& operator<<=(uint32_t bits);
/// \brief Shift right by the given number of bits. Negative values will
BasicDecimal128& operator>>=(uint32_t bits);
/// \brief Get the high bits of the two's complement representation of the number.
inline int64_t high_bits() const { return high_bits_; }
/// \brief Get the low bits of the two's complement representation of the number.
inline uint64_t low_bits() const { return low_bits_; }
/// \brief Return the raw bytes of the value in little-endian byte order.
std::array<uint8_t, 16> ToBytes() const;
void ToBytes(uint8_t* out) const;
/// \brief seperate the integer and fractional parts for the given scale.
void GetWholeAndFraction(int32_t scale, BasicDecimal128* whole,
BasicDecimal128* fraction) const;
/// \brief Scale multiplier for given scale value.
static const BasicDecimal128& GetScaleMultiplier(int32_t scale);
/// \brief Convert BasicDecimal128 from one scale to another
DecimalStatus Rescale(int32_t original_scale, int32_t new_scale,
BasicDecimal128* out) const;
/// \brief Scale up.
BasicDecimal128 IncreaseScaleBy(int32_t increase_by) const;
/// \brief Scale down.
/// - If 'round' is true, the right-most digits are dropped and the result value is
/// rounded up (+1 for +ve, -1 for -ve) based on the value of the dropped digits
/// (>= 10^reduce_by / 2).
/// - If 'round' is false, the right-most digits are simply dropped.
BasicDecimal128 ReduceScaleBy(int32_t reduce_by, bool round = true) const;
// returns 1 for positive and zero decimal values, -1 for negative decimal values.
inline int64_t Sign() const { return 1 | (high_bits_ >> 63); }
/// \brief count the number of leading binary zeroes.
int32_t CountLeadingBinaryZeros() const;
/// \brief Get the maximum valid unscaled decimal value.
static const BasicDecimal128& GetMaxValue();
private:
uint64_t low_bits_;
int64_t high_bits_;
};
ARROW_EXPORT bool operator==(const BasicDecimal128& left, const BasicDecimal128& right);
ARROW_EXPORT bool operator!=(const BasicDecimal128& left, const BasicDecimal128& right);
ARROW_EXPORT bool operator<(const BasicDecimal128& left, const BasicDecimal128& right);
ARROW_EXPORT bool operator<=(const BasicDecimal128& left, const BasicDecimal128& right);
ARROW_EXPORT bool operator>(const BasicDecimal128& left, const BasicDecimal128& right);
ARROW_EXPORT bool operator>=(const BasicDecimal128& left, const BasicDecimal128& right);
ARROW_EXPORT BasicDecimal128 operator-(const BasicDecimal128& operand);
ARROW_EXPORT BasicDecimal128 operator~(const BasicDecimal128& operand);
ARROW_EXPORT BasicDecimal128 operator+(const BasicDecimal128& left,
const BasicDecimal128& right);
ARROW_EXPORT BasicDecimal128 operator-(const BasicDecimal128& left,
const BasicDecimal128& right);
ARROW_EXPORT BasicDecimal128 operator*(const BasicDecimal128& left,
const BasicDecimal128& right);
ARROW_EXPORT BasicDecimal128 operator/(const BasicDecimal128& left,
const BasicDecimal128& right);
ARROW_EXPORT BasicDecimal128 operator%(const BasicDecimal128& left,
const BasicDecimal128& right);
} // namespace arrow