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 // 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 <climits>
 #include <cstdint>
 #include <cstring>
 #include <limits>
 #include <string>
 #include <type_traits>
 
 #include "arrow/util/endian.h"
 #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,
 };
 
 template <typename Derived, int BIT_WIDTH, int NWORDS = BIT_WIDTH / 64>
 class GenericBasicDecimal {
  protected:
   struct LittleEndianArrayTag {};
 
 #if ARROW_LITTLE_ENDIAN
   static constexpr int kHighWordIndex = NWORDS - 1;
   static constexpr int kLowWordIndex = 0;
 #else
   static constexpr int kHighWordIndex = 0;
   static constexpr int kLowWordIndex = NWORDS - 1;
 #endif
 
  public:
   static constexpr int kBitWidth = BIT_WIDTH;
   static constexpr int kByteWidth = kBitWidth / 8;
   static constexpr int kNumWords = NWORDS;
 
   // A constructor tag to introduce a little-endian encoded array
   static constexpr LittleEndianArrayTag LittleEndianArray{};
 
   using WordArray = std::array<uint64_t, NWORDS>;
 
   /// \brief Empty constructor creates a decimal with a value of 0.
   constexpr GenericBasicDecimal() noexcept : array_({0}) {}
 
   /// \brief Create a decimal from the two's complement representation.
   ///
   /// Input array is assumed to be in native endianness.
   explicit constexpr GenericBasicDecimal(const WordArray& array) noexcept
       : array_(array) {}
 
   /// \brief Create a decimal from the two's complement representation.
   ///
   /// Input array is assumed to be in little endianness, with native endian elements.
   GenericBasicDecimal(LittleEndianArrayTag, const WordArray& array) noexcept
       : GenericBasicDecimal(bit_util::little_endian::ToNative(array)) {}
 
   /// \brief Create a decimal from any integer not wider than 64 bits.
   template <typename T,
             typename = typename std::enable_if<
                 std::is_integral<T>::value && (sizeof(T) <= sizeof(uint64_t)), T>::type>
   constexpr GenericBasicDecimal(T value) noexcept  // NOLINT(runtime/explicit)
       : array_(WordsFromLowBits(value)) {}
 
   /// \brief Create a decimal from an array of bytes.
   ///
   /// Bytes are assumed to be in native-endian byte order.
   explicit GenericBasicDecimal(const uint8_t* bytes) {
     memcpy(array_.data(), bytes, sizeof(array_));
   }
 
   /// \brief Get the bits of the two's complement representation of the number.
   ///
   /// The elements are in native endian order. The bits within each uint64_t element
   /// are in native endian order. For example, on a little endian machine,
   /// BasicDecimal128(123).native_endian_array() = {123, 0};
   /// but on a big endian machine,
   /// BasicDecimal128(123).native_endian_array() = {0, 123};
   constexpr const WordArray& native_endian_array() const { return array_; }
 
   /// \brief Get the bits of the two's complement representation of the number.
   ///
   /// The elements are in little endian order. However, the bits within each
   /// uint64_t element are in native endian order.
   /// For example, BasicDecimal128(123).little_endian_array() = {123, 0};
   WordArray little_endian_array() const {
     return bit_util::little_endian::FromNative(array_);
   }
 
   const uint8_t* native_endian_bytes() const {
     return reinterpret_cast<const uint8_t*>(array_.data());
   }
 
   uint8_t* mutable_native_endian_bytes() {
     return reinterpret_cast<uint8_t*>(array_.data());
   }
 
   /// \brief Return the raw bytes of the value in native-endian byte order.
   std::array<uint8_t, kByteWidth> ToBytes() const {
     std::array<uint8_t, kByteWidth> out{{0}};
     memcpy(out.data(), array_.data(), kByteWidth);
     return out;
   }
 
   /// \brief Copy the raw bytes of the value in native-endian byte order.
   void ToBytes(uint8_t* out) const { memcpy(out, array_.data(), kByteWidth); }
 
   /// Return 1 if positive or zero, -1 if strictly negative.
   int64_t Sign() const {
     return 1 | (static_cast<int64_t>(array_[kHighWordIndex]) >> 63);
   }
 
   bool IsNegative() const { return static_cast<int64_t>(array_[kHighWordIndex]) < 0; }
 
   explicit operator bool() const { return array_ != WordArray{}; }
 
   friend bool operator==(const GenericBasicDecimal& left,
                          const GenericBasicDecimal& right) {
     return left.array_ == right.array_;
   }
 
   friend bool operator!=(const GenericBasicDecimal& left,
                          const GenericBasicDecimal& right) {
     return left.array_ != right.array_;
   }
 
  protected:
   WordArray array_;
 
   template <typename T>
   static constexpr uint64_t SignExtend(T low_bits) noexcept {
     return low_bits >= T{} ? uint64_t{0} : ~uint64_t{0};
   }
 
   template <typename T>
   static constexpr WordArray WordsFromLowBits(T low_bits) {
     WordArray words{};
     if (low_bits < T{}) {
       for (auto& word : words) {
         word = ~uint64_t{0};
       }
     }
     words[kLowWordIndex] = static_cast<uint64_t>(low_bits);
     return words;
   }
 };
 
 template <typename DigitType>
 class ARROW_EXPORT SmallBasicDecimal {
  public:
   static_assert(
       std::is_same_v<DigitType, int32_t> || std::is_same_v<DigitType, int64_t>,
       "for bitwidths larger than 64 bits use BasicDecimal128 and BasicDecimal256");
 
   static constexpr int kMaxPrecision = std::numeric_limits<DigitType>::digits10;
   static constexpr int kMaxScale = kMaxPrecision;
   static constexpr int kBitWidth = sizeof(DigitType) * CHAR_BIT;
   static constexpr int kByteWidth = sizeof(DigitType);
 
   using WordArray = std::array<std::make_unsigned_t<DigitType>, 1>;
 
   /// \brief Empty constructor creates a decimal with a value of 0.
   constexpr SmallBasicDecimal() noexcept : value_(0) {}
 
   /// \brief Create a decimal from any integer not wider than 64 bits.
   template <typename T,
             typename = typename std::enable_if<
                 std::is_integral<T>::value && (sizeof(T) <= sizeof(int64_t)), T>::type>
   constexpr SmallBasicDecimal(T value) noexcept  // NOLINT(runtime/explicit)
       : value_(static_cast<DigitType>(value)) {}
 
   /// \brief Create a decimal from an array of bytes.
   ///
   /// Bytes are assumed to be in native-endian byte order.
   explicit SmallBasicDecimal(const uint8_t* bytes) {
     memcpy(&value_, bytes, sizeof(value_));
   }
 
   constexpr const WordArray native_endian_array() const {
     return WordArray{static_cast<typename WordArray::value_type>(value_)};
   }
 
   constexpr const WordArray little_endian_array() const {
     return bit_util::little_endian::FromNative(
         WordArray{static_cast<typename WordArray::value_type>(value_)});
   }
 
   const uint8_t* native_endian_bytes() const {
     return reinterpret_cast<const uint8_t*>(&value_);
   }
 
   uint8_t* mutable_native_endian_bytes() { return reinterpret_cast<uint8_t*>(&value_); }
 
   /// \brief Return the raw bytes of the value in native-endian byte order.
   std::array<uint8_t, kByteWidth> ToBytes() const {
     std::array<uint8_t, kByteWidth> out{{0}};
     memcpy(out.data(), &value_, kByteWidth);
     return out;
   }
 
   /// \brief Copy the raw bytes of the value in native-endian byte order
   void ToBytes(uint8_t* out) const { memcpy(out, &value_, kByteWidth); }
 
   /// \brief Return 1 if positive or 0, -1 if strictly negative
   int64_t Sign() const { return 1 | (value_ >> (kBitWidth - 1)); }
 
   bool IsNegative() const { return value_ < 0; }
 
   explicit operator bool() const { return value_ != 0; }
 
   friend bool operator==(const SmallBasicDecimal& left, const SmallBasicDecimal& right) {
     return left.value_ == right.value_;
   }
 
   friend bool operator!=(const SmallBasicDecimal& left, const SmallBasicDecimal& right) {
     return left.value_ != right.value_;
   }
 
   DigitType value() const { return value_; }
 
   /// \brief count the number of leading binary zeroes.
   int32_t CountLeadingBinaryZeros() const;
 
   constexpr uint64_t low_bits() const { return static_cast<uint64_t>(value_); }
 
  protected:
   DigitType value_;
 };
 
 class BasicDecimal32;
 class BasicDecimal64;
 
 ARROW_EXPORT bool operator<(const BasicDecimal32& left, const BasicDecimal32& right);
 ARROW_EXPORT bool operator<=(const BasicDecimal32& left, const BasicDecimal32& right);
 ARROW_EXPORT bool operator>(const BasicDecimal32& left, const BasicDecimal32& right);
 ARROW_EXPORT bool operator>=(const BasicDecimal32& left, const BasicDecimal32& right);
 
 ARROW_EXPORT BasicDecimal32 operator-(const BasicDecimal32& self);
 ARROW_EXPORT BasicDecimal32 operator~(const BasicDecimal32& self);
 ARROW_EXPORT BasicDecimal32 operator+(const BasicDecimal32& left,
                                       const BasicDecimal32& right);
 ARROW_EXPORT BasicDecimal32 operator-(const BasicDecimal32& left,
                                       const BasicDecimal32& right);
 ARROW_EXPORT BasicDecimal32 operator*(const BasicDecimal32& left,
                                       const BasicDecimal32& right);
 ARROW_EXPORT BasicDecimal32 operator/(const BasicDecimal32& left,
                                       const BasicDecimal32& right);
 ARROW_EXPORT BasicDecimal32 operator%(const BasicDecimal32& left,
                                       const BasicDecimal32& right);
 
 class ARROW_EXPORT BasicDecimal32 : public SmallBasicDecimal<int32_t> {
  public:
   using SmallBasicDecimal<int32_t>::SmallBasicDecimal;
   using ValueType = int32_t;
 
   /// \brief Negate the current value (in-place)
   BasicDecimal32& Negate();
 
   /// \brief Absolute value (in-place)
   BasicDecimal32& Abs() { return *this < 0 ? Negate() : *this; }
 
   /// \brief Absolute value
   static BasicDecimal32 Abs(const BasicDecimal32& in) {
     BasicDecimal32 result(in);
     return result.Abs();
   }
 
   /// \brief Add a number to this one. The result is truncated to 32 bits.
   BasicDecimal32& operator+=(const BasicDecimal32& right) {
     value_ += right.value_;
     return *this;
   }
 
   /// \brief Subtract a number from this one. The result is truncated to 32 bits.
   BasicDecimal32& operator-=(const BasicDecimal32& right) {
     value_ -= right.value_;
     return *this;
   }
 
   /// \brief Multiply this number by another. The result is truncated to 32 bits.
   BasicDecimal32& operator*=(const BasicDecimal32& right) {
     value_ *= static_cast<uint64_t>(right.value_);
     return *this;
   }
 
   /// \brief Divide this number by the divisor 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 BasicDecimal32& divisor, BasicDecimal32* result,
                        BasicDecimal32* remainder) const;
 
   /// \brief In-place division
   BasicDecimal32& operator/=(const BasicDecimal32& right) {
     value_ /= right.value_;
     return *this;
   }
 
   /// \brief Bitwise "or" between two BasicDecimal32s
   BasicDecimal32& operator|=(const BasicDecimal32& right) {
     value_ |= right.value_;
     return *this;
   }
 
   /// \brief Bitwise "and" between two BasicDecimal32s
   BasicDecimal32& operator&=(const BasicDecimal32& right) {
     value_ &= right.value_;
     return *this;
   }
   /// \brief Shift left by the given number of bits.
   BasicDecimal32& operator<<=(uint32_t bits);
 
   BasicDecimal32 operator<<(uint32_t bits) const {
     auto res = *this;
     res <<= bits;
     return res;
   }
 
   /// \brief Shift right by the given number of bits.
   ///
   /// Negative values will sign-extend
   BasicDecimal32& operator>>=(uint32_t bits);
 
   BasicDecimal32 operator>>(uint32_t bits) const {
     auto res = *this;
     res >>= bits;
     return res;
   }
 
   /// \brief Convert BasicDecimal32 from one scale to another
   DecimalStatus Rescale(int32_t original_scale, int32_t new_scale,
                         BasicDecimal32* out) const;
 
   void GetWholeAndFraction(int scale, BasicDecimal32* whole,
                            BasicDecimal32* fraction) const;
 
   /// \brief Scale up.
   BasicDecimal32 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.
   BasicDecimal32 ReduceScaleBy(int32_t reduce_by, bool round = true) const;
 
   /// \brief Whether this number fits in the given precision
   ///
   /// Return true if the number of significant digits is less or equal to 'precision'.
   bool FitsInPrecision(int32_t precision) const;
 
   /// \brief Get the maximum valid unscaled decimal value.
   static const BasicDecimal32& GetMaxValue();
   /// \brief Get the maximum valid unscaled decimal value for the given precision.
   static BasicDecimal32 GetMaxValue(int32_t precision);
 
   /// \brief Get the maximum decimal value (is not a valid value).
   static constexpr BasicDecimal32 GetMaxSentinel() {
     return BasicDecimal32(std::numeric_limits<int32_t>::max());
   }
 
   /// \brief Get the minimum decimal value (is not a valid value).
   static constexpr BasicDecimal32 GetMinSentinel() {
     return BasicDecimal32(std::numeric_limits<int32_t>::min());
   }
 
   /// \brief Scale multiplier for a given scale value.
   static const BasicDecimal32& GetScaleMultiplier(int32_t scale);
   /// \brief Half-scale multiplier for a given scale value.
   static const BasicDecimal32& GetHalfScaleMultiplier(int32_t scale);
 
   explicit operator BasicDecimal64() const;
 };
 
 ARROW_EXPORT bool operator<(const BasicDecimal64& left, const BasicDecimal64& right);
 ARROW_EXPORT bool operator<=(const BasicDecimal64& left, const BasicDecimal64& right);
 ARROW_EXPORT bool operator>(const BasicDecimal64& left, const BasicDecimal64& right);
 ARROW_EXPORT bool operator>=(const BasicDecimal64& left, const BasicDecimal64& right);
 
 ARROW_EXPORT BasicDecimal64 operator-(const BasicDecimal64& self);
 ARROW_EXPORT BasicDecimal64 operator~(const BasicDecimal64& self);
 ARROW_EXPORT BasicDecimal64 operator+(const BasicDecimal64& left,
                                       const BasicDecimal64& right);
 ARROW_EXPORT BasicDecimal64 operator-(const BasicDecimal64& left,
                                       const BasicDecimal64& right);
 ARROW_EXPORT BasicDecimal64 operator*(const BasicDecimal64& left,
                                       const BasicDecimal64& right);
 ARROW_EXPORT BasicDecimal64 operator/(const BasicDecimal64& left,
                                       const BasicDecimal64& right);
 ARROW_EXPORT BasicDecimal64 operator%(const BasicDecimal64& left,
                                       const BasicDecimal64& right);
 
 class ARROW_EXPORT BasicDecimal64 : public SmallBasicDecimal<int64_t> {
  public:
   using SmallBasicDecimal<int64_t>::SmallBasicDecimal;
   using ValueType = int64_t;
 
   /// \brief Negate the current value (in-place)
   BasicDecimal64& Negate();
 
   /// \brief Absolute value (in-place)
   BasicDecimal64& Abs() { return *this < 0 ? Negate() : *this; }
 
   /// \brief Absolute value
   static BasicDecimal64 Abs(const BasicDecimal64& in) {
     BasicDecimal64 result(in);
     return result.Abs();
   }
 
   /// \brief Add a number to this one. The result is truncated to 32 bits.
   BasicDecimal64& operator+=(const BasicDecimal64& right) {
     value_ += right.value_;
     return *this;
   }
 
   /// \brief Subtract a number from this one. The result is truncated to 32 bits.
   BasicDecimal64& operator-=(const BasicDecimal64& right) {
     value_ -= right.value_;
     return *this;
   }
 
   /// \brief Multiply this number by another. The result is truncated to 32 bits.
   BasicDecimal64& operator*=(const BasicDecimal64& right) {
     value_ *= static_cast<uint64_t>(right.value_);
     return *this;
   }
 
   /// \brief Divide this number by the divisor 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 BasicDecimal64& divisor, BasicDecimal64* result,
                        BasicDecimal64* remainder) const;
 
   /// \brief In-place division
   BasicDecimal64& operator/=(const BasicDecimal64& right) {
     value_ /= right.value_;
     return *this;
   }
 
   /// \brief Bitwise "or" between two BasicDecimal64s
   BasicDecimal64& operator|=(const BasicDecimal64& right) {
     value_ |= right.value_;
     return *this;
   }
 
   /// \brief Bitwise "and" between two BasicDecimal64s
   BasicDecimal64& operator&=(const BasicDecimal64& right) {
     value_ &= right.value_;
     return *this;
   }
 
   /// \brief Shift left by the given number of bits.
   BasicDecimal64& operator<<=(uint32_t bits);
 
   BasicDecimal64 operator<<(uint32_t bits) const {
     auto res = *this;
     res <<= bits;
     return res;
   }
 
   /// \brief Shift right by the given number of bits.
   ///
   /// Negative values will sign-extend
   BasicDecimal64& operator>>=(uint32_t bits);
 
   BasicDecimal64 operator>>(uint32_t bits) const {
     auto res = *this;
     res >>= bits;
     return res;
   }
 
   /// \brief Convert BasicDecimal32 from one scale to another
   DecimalStatus Rescale(int32_t original_scale, int32_t new_scale,
                         BasicDecimal64* out) const;
 
   void GetWholeAndFraction(int scale, BasicDecimal64* whole,
                            BasicDecimal64* fraction) const;
 
   /// \brief Scale up.
   BasicDecimal64 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.
   BasicDecimal64 ReduceScaleBy(int32_t reduce_by, bool round = true) const;
 
   /// \brief Whether this number fits in the given precision
   ///
   /// Return true if the number of significant digits is less or equal to 'precision'.
   bool FitsInPrecision(int32_t precision) const;
 
   /// \brief Get the maximum valid unscaled decimal value.
   static const BasicDecimal64& GetMaxValue();
   /// \brief Get the maximum valid unscaled decimal value for the given precision.
   static BasicDecimal64 GetMaxValue(int32_t precision);
 
   /// \brief Get the maximum decimal value (is not a valid value).
   static constexpr BasicDecimal64 GetMaxSentinel() {
     return BasicDecimal64(std::numeric_limits<int32_t>::max());
   }
 
   /// \brief Get the minimum decimal value (is not a valid value).
   static constexpr BasicDecimal64 GetMinSentinel() {
     return BasicDecimal64(std::numeric_limits<int32_t>::min());
   }
 
   /// \brief Scale multiplier for a given scale value.
   static const BasicDecimal64& GetScaleMultiplier(int32_t scale);
   /// \brief Half-scale multiplier for a given scale value.
   static const BasicDecimal64& GetHalfScaleMultiplier(int32_t scale);
 };
 
 /// 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 GenericBasicDecimal<BasicDecimal128, 128> {
  public:
   static constexpr int kMaxPrecision = 38;
   static constexpr int kMaxScale = 38;
 
   using GenericBasicDecimal::GenericBasicDecimal;
 
   constexpr BasicDecimal128() noexcept : GenericBasicDecimal() {}
 
   /// \brief Create a BasicDecimal128 from the two's complement representation.
 #if ARROW_LITTLE_ENDIAN
   constexpr BasicDecimal128(int64_t high, uint64_t low) noexcept
       : BasicDecimal128(WordArray{low, static_cast<uint64_t>(high)}) {}
 #else
   constexpr BasicDecimal128(int64_t high, uint64_t low) noexcept
       : BasicDecimal128(WordArray{static_cast<uint64_t>(high), low}) {}
 #endif
 
   /// \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);
 
   BasicDecimal128 operator<<(uint32_t bits) const {
     auto res = *this;
     res <<= bits;
     return res;
   }
 
   /// \brief Shift right by the given number of bits.
   ///
   /// Negative values will sign-extend.
   BasicDecimal128& operator>>=(uint32_t bits);
 
   BasicDecimal128 operator>>(uint32_t bits) const {
     auto res = *this;
     res >>= bits;
     return res;
   }
 
   /// \brief Get the high bits of the two's complement representation of the number.
   constexpr int64_t high_bits() const {
 #if ARROW_LITTLE_ENDIAN
     return static_cast<int64_t>(array_[1]);
 #else
     return static_cast<int64_t>(array_[0]);
 #endif
   }
 
   /// \brief Get the low bits of the two's complement representation of the number.
   constexpr uint64_t low_bits() const {
 #if ARROW_LITTLE_ENDIAN
     return array_[0];
 #else
     return array_[1];
 #endif
   }
 
   /// \brief separate 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 Half-scale multiplier for given scale value.
   static const BasicDecimal128& GetHalfScaleMultiplier(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;
 
   /// \brief Whether this number fits in the given precision
   ///
   /// Return true if the number of significant digits is less or equal to `precision`.
   bool FitsInPrecision(int32_t precision) const;
 
   /// \brief count the number of leading binary zeroes.
   int32_t CountLeadingBinaryZeros() const;
 
   /// \brief Get the maximum valid unscaled decimal value.
   static const BasicDecimal128& GetMaxValue();
 
   /// \brief Get the maximum valid unscaled decimal value for the given precision.
   static BasicDecimal128 GetMaxValue(int32_t precision);
 
   /// \brief Get the maximum decimal value (is not a valid value).
   static constexpr BasicDecimal128 GetMaxSentinel() {
     return BasicDecimal128(/*high=*/std::numeric_limits<int64_t>::max(),
                            /*low=*/std::numeric_limits<uint64_t>::max());
   }
   /// \brief Get the minimum decimal value (is not a valid value).
   static constexpr BasicDecimal128 GetMinSentinel() {
     return BasicDecimal128(/*high=*/std::numeric_limits<int64_t>::min(),
                            /*low=*/std::numeric_limits<uint64_t>::min());
   }
 };
 
 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);
 
 class ARROW_EXPORT BasicDecimal256 : public GenericBasicDecimal<BasicDecimal256, 256> {
  public:
   using GenericBasicDecimal::GenericBasicDecimal;
 
   static constexpr int kMaxPrecision = 76;
   static constexpr int kMaxScale = 76;
 
   constexpr BasicDecimal256() noexcept : GenericBasicDecimal() {}
 
   explicit BasicDecimal256(const BasicDecimal128& value) noexcept
       : BasicDecimal256(bit_util::little_endian::ToNative<uint64_t, 4>(
             {value.low_bits(), static_cast<uint64_t>(value.high_bits()),
              SignExtend(value.high_bits()), SignExtend(value.high_bits())})) {}
 
   explicit BasicDecimal256(const BasicDecimal64& value) noexcept
       : BasicDecimal256(bit_util::little_endian::ToNative<uint64_t, 4>(
             {value.low_bits(), SignExtend(value.value()), SignExtend(value.value()),
              SignExtend(value.value())})) {}
 
   explicit BasicDecimal256(const BasicDecimal32& value) noexcept
       : BasicDecimal256(bit_util::little_endian::ToNative<uint64_t, 4>(
             {value.low_bits(), SignExtend(value.value()), SignExtend(value.value()),
              SignExtend(value.value())})) {}
 
   /// \brief Negate the current value (in-place)
   BasicDecimal256& Negate();
 
   /// \brief Absolute value (in-place)
   BasicDecimal256& Abs();
 
   /// \brief Absolute value
   static BasicDecimal256 Abs(const BasicDecimal256& left);
 
   /// \brief Add a number to this one. The result is truncated to 256 bits.
   BasicDecimal256& operator+=(const BasicDecimal256& right);
 
   /// \brief Subtract a number from this one. The result is truncated to 256 bits.
   BasicDecimal256& operator-=(const BasicDecimal256& right);
 
   /// \brief Get the lowest bits of the two's complement representation of the number.
   uint64_t low_bits() const { return bit_util::little_endian::Make(array_)[0]; }
 
   /// \brief separate the integer and fractional parts for the given scale.
   void GetWholeAndFraction(int32_t scale, BasicDecimal256* whole,
                            BasicDecimal256* fraction) const;
 
   /// \brief Scale multiplier for given scale value.
   static const BasicDecimal256& GetScaleMultiplier(int32_t scale);
   /// \brief Half-scale multiplier for given scale value.
   static const BasicDecimal256& GetHalfScaleMultiplier(int32_t scale);
 
   /// \brief Convert BasicDecimal256 from one scale to another
   DecimalStatus Rescale(int32_t original_scale, int32_t new_scale,
                         BasicDecimal256* out) const;
 
   /// \brief Scale up.
   BasicDecimal256 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 positive, -1 for negative) based on the value of the
   ///   dropped digits (>= 10^reduce_by / 2).
   /// - If 'round' is false, the right-most digits are simply dropped.
   BasicDecimal256 ReduceScaleBy(int32_t reduce_by, bool round = true) const;
 
   /// \brief Whether this number fits in the given precision
   ///
   /// Return true if the number of significant digits is less or equal to `precision`.
   bool FitsInPrecision(int32_t precision) const;
 
   /// \brief Multiply this number by another number. The result is truncated to 256 bits.
   BasicDecimal256& operator*=(const BasicDecimal256& 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 BasicDecimal256& divisor, BasicDecimal256* result,
                        BasicDecimal256* remainder) const;
 
   /// \brief Shift left by the given number of bits.
   BasicDecimal256& operator<<=(uint32_t bits);
 
   BasicDecimal256 operator<<(uint32_t bits) const {
     auto res = *this;
     res <<= bits;
     return res;
   }
 
   /// \brief Shift right by the given number of bits.
   ///
   /// Negative values will sign-extend.
   BasicDecimal256& operator>>=(uint32_t bits);
 
   BasicDecimal256 operator>>(uint32_t bits) const {
     auto res = *this;
     res >>= bits;
     return res;
   }
 
   /// \brief In-place division.
   BasicDecimal256& operator/=(const BasicDecimal256& right);
 
   /// \brief Get the maximum valid unscaled decimal value for the given precision.
   static BasicDecimal256 GetMaxValue(int32_t precision);
 
   /// \brief Get the maximum decimal value (is not a valid value).
   static constexpr BasicDecimal256 GetMaxSentinel() {
 #if ARROW_LITTLE_ENDIAN
     return BasicDecimal256({std::numeric_limits<uint64_t>::max(),
                             std::numeric_limits<uint64_t>::max(),
                             std::numeric_limits<uint64_t>::max(),
                             static_cast<uint64_t>(std::numeric_limits<int64_t>::max())});
 #else
     return BasicDecimal256({static_cast<uint64_t>(std::numeric_limits<int64_t>::max()),
                             std::numeric_limits<uint64_t>::max(),
                             std::numeric_limits<uint64_t>::max(),
                             std::numeric_limits<uint64_t>::max()});
 #endif
   }
   /// \brief Get the minimum decimal value (is not a valid value).
   static constexpr BasicDecimal256 GetMinSentinel() {
 #if ARROW_LITTLE_ENDIAN
     return BasicDecimal256(
         {0, 0, 0, static_cast<uint64_t>(std::numeric_limits<int64_t>::min())});
 #else
     return BasicDecimal256(
         {static_cast<uint64_t>(std::numeric_limits<int64_t>::min()), 0, 0, 0});
 #endif
   }
 };
 
 ARROW_EXPORT bool operator<(const BasicDecimal256& left, const BasicDecimal256& right);
 
 ARROW_EXPORT inline bool operator<=(const BasicDecimal256& left,
                                     const BasicDecimal256& right) {
   return !operator<(right, left);
 }
 
 ARROW_EXPORT inline bool operator>(const BasicDecimal256& left,
                                    const BasicDecimal256& right) {
   return operator<(right, left);
 }
 
 ARROW_EXPORT inline bool operator>=(const BasicDecimal256& left,
                                     const BasicDecimal256& right) {
   return !operator<(left, right);
 }
 
 ARROW_EXPORT BasicDecimal256 operator-(const BasicDecimal256& operand);
 ARROW_EXPORT BasicDecimal256 operator~(const BasicDecimal256& operand);
 ARROW_EXPORT BasicDecimal256 operator+(const BasicDecimal256& left,
                                        const BasicDecimal256& right);
 ARROW_EXPORT BasicDecimal256 operator*(const BasicDecimal256& left,
                                        const BasicDecimal256& right);
 ARROW_EXPORT BasicDecimal256 operator/(const BasicDecimal256& left,
                                        const BasicDecimal256& right);
 
 }  // namespace arrow

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