2022-05-23 00:16:32 +04:00

473 lines
18 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 <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 ARROW_EXPORT GenericBasicDecimal {
protected:
struct LittleEndianArrayTag {};
#if ARROW_LITTLE_ENDIAN
static constexpr int kHighWordIndex = NWORDS - 1;
#else
static constexpr int kHighWordIndex = 0;
#endif
public:
static constexpr int kBitWidth = BIT_WIDTH;
static constexpr int kByteWidth = kBitWidth / 8;
// 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.
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 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; }
protected:
WordArray array_;
};
/// 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 Convert any integer value into a BasicDecimal128.
template <typename T,
typename = typename std::enable_if<
std::is_integral<T>::value && (sizeof(T) <= sizeof(uint64_t)), T>::type>
constexpr BasicDecimal128(T value) noexcept
: BasicDecimal128(value >= T{0} ? 0 : -1, static_cast<uint64_t>(value)) { // NOLINT
}
/// \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
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 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> {
private:
// Due to a bug in clang, we have to declare the extend method prior to its
// usage.
template <typename T>
static constexpr uint64_t extend(T low_bits) noexcept {
return low_bits >= T() ? uint64_t{0} : ~uint64_t{0};
}
public:
using GenericBasicDecimal::GenericBasicDecimal;
static constexpr int kMaxPrecision = 76;
static constexpr int kMaxScale = 76;
constexpr BasicDecimal256() noexcept : GenericBasicDecimal() {}
/// \brief Convert any integer value into a BasicDecimal256.
template <typename T,
typename = typename std::enable_if<
std::is_integral<T>::value && (sizeof(T) <= sizeof(uint64_t)), T>::type>
constexpr BasicDecimal256(T value) noexcept
: BasicDecimal256(bit_util::little_endian::ToNative<uint64_t, 4>(
{static_cast<uint64_t>(value), extend(value), extend(value),
extend(value)})) {}
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()),
extend(value.high_bits()), extend(value.high_bits())})) {}
/// \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 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 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 inline bool operator==(const BasicDecimal256& left,
const BasicDecimal256& right) {
return left.native_endian_array() == right.native_endian_array();
}
ARROW_EXPORT inline bool operator!=(const BasicDecimal256& left,
const BasicDecimal256& right) {
return left.native_endian_array() != right.native_endian_array();
}
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