tvl-depot/absl/numeric/int128.h
Abseil Team 0d40cb771e Changes imported from Abseil "staging" branch:
- 5d9197f54029dd26e144365738e99a1d3582cc18 Change alignment requirement for uint128. by Alex Strelnikov <strel@google.com>

GitOrigin-RevId: 5d9197f54029dd26e144365738e99a1d3582cc18
Change-Id: Ibac0689c5d95a019441be9d4479b65c5aba1c286
2018-02-23 11:27:57 -05:00

656 lines
21 KiB
C++

//
// Copyright 2017 The Abseil Authors.
//
// Licensed 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.
//
// -----------------------------------------------------------------------------
// File: int128.h
// -----------------------------------------------------------------------------
//
// This header file defines 128-bit integer types.
//
// Currently, this file defines `uint128`, an unsigned 128-bit integer; a signed
// 128-bit integer is forthcoming.
#ifndef ABSL_NUMERIC_INT128_H_
#define ABSL_NUMERIC_INT128_H_
#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstring>
#include <iosfwd>
#include <limits>
#include "absl/base/config.h"
#include "absl/base/macros.h"
#include "absl/base/port.h"
namespace absl {
// uint128
//
// An unsigned 128-bit integer type. The API is meant to mimic an intrinsic type
// as closely as is practical, including exhibiting undefined behavior in
// analogous cases (e.g. division by zero). This type is intended to be a
// drop-in replacement once C++ supports an intrinsic `uint128_t` type; when
// that occurs, existing well-behaved uses of `uint128` will continue to work
// using that new type.
//
// Note: code written with this type will continue to compile once `uint128_t`
// is introduced, provided the replacement helper functions
// `Uint128(Low|High)64()` and `MakeUint128()` are made.
//
// A `uint128` supports the following:
//
// * Implicit construction from integral types
// * Explicit conversion to integral types
//
// Additionally, if your compiler supports `__int128`, `uint128` is
// interoperable with that type. (Abseil checks for this compatibility through
// the `ABSL_HAVE_INTRINSIC_INT128` macro.)
//
// However, a `uint128` differs from intrinsic integral types in the following
// ways:
//
// * Errors on implicit conversions that do not preserve value (such as
// loss of precision when converting to float values).
// * Requires explicit construction from and conversion to floating point
// types.
// * Conversion to integral types requires an explicit static_cast() to
// mimic use of the `-Wnarrowing` compiler flag.
// * The alignment requirement of `uint128` may differ from that of an
// intrinsic 128-bit integer type depending on platform and build
// configuration.
//
// Example:
//
// float y = absl::Uint128Max(); // Error. uint128 cannot be implicitly
// // converted to float.
//
// absl::uint128 v;
// absl::uint64_t i = v; // Error
// absl::uint64_t i = static_cast<uint64_t>(v); // OK
//
class
#if defined(ABSL_HAVE_INTRINSIC_INT128)
alignas(unsigned __int128)
#endif // ABSL_HAVE_INTRINSIC_INT128
uint128 {
public:
uint128() = default;
// Constructors from arithmetic types
constexpr uint128(int v); // NOLINT(runtime/explicit)
constexpr uint128(unsigned int v); // NOLINT(runtime/explicit)
constexpr uint128(long v); // NOLINT(runtime/int)
constexpr uint128(unsigned long v); // NOLINT(runtime/int)
constexpr uint128(long long v); // NOLINT(runtime/int)
constexpr uint128(unsigned long long v); // NOLINT(runtime/int)
#ifdef ABSL_HAVE_INTRINSIC_INT128
constexpr uint128(__int128 v); // NOLINT(runtime/explicit)
constexpr uint128(unsigned __int128 v); // NOLINT(runtime/explicit)
#endif // ABSL_HAVE_INTRINSIC_INT128
explicit uint128(float v);
explicit uint128(double v);
explicit uint128(long double v);
// Assignment operators from arithmetic types
uint128& operator=(int v);
uint128& operator=(unsigned int v);
uint128& operator=(long v); // NOLINT(runtime/int)
uint128& operator=(unsigned long v); // NOLINT(runtime/int)
uint128& operator=(long long v); // NOLINT(runtime/int)
uint128& operator=(unsigned long long v); // NOLINT(runtime/int)
#ifdef ABSL_HAVE_INTRINSIC_INT128
uint128& operator=(__int128 v);
uint128& operator=(unsigned __int128 v);
#endif // ABSL_HAVE_INTRINSIC_INT128
// Conversion operators to other arithmetic types
constexpr explicit operator bool() const;
constexpr explicit operator char() const;
constexpr explicit operator signed char() const;
constexpr explicit operator unsigned char() const;
constexpr explicit operator char16_t() const;
constexpr explicit operator char32_t() const;
constexpr explicit operator wchar_t() const;
constexpr explicit operator short() const; // NOLINT(runtime/int)
// NOLINTNEXTLINE(runtime/int)
constexpr explicit operator unsigned short() const;
constexpr explicit operator int() const;
constexpr explicit operator unsigned int() const;
constexpr explicit operator long() const; // NOLINT(runtime/int)
// NOLINTNEXTLINE(runtime/int)
constexpr explicit operator unsigned long() const;
// NOLINTNEXTLINE(runtime/int)
constexpr explicit operator long long() const;
// NOLINTNEXTLINE(runtime/int)
constexpr explicit operator unsigned long long() const;
#ifdef ABSL_HAVE_INTRINSIC_INT128
constexpr explicit operator __int128() const;
constexpr explicit operator unsigned __int128() const;
#endif // ABSL_HAVE_INTRINSIC_INT128
explicit operator float() const;
explicit operator double() const;
explicit operator long double() const;
// Trivial copy constructor, assignment operator and destructor.
// Arithmetic operators.
uint128& operator+=(uint128 other);
uint128& operator-=(uint128 other);
uint128& operator*=(uint128 other);
// Long division/modulo for uint128.
uint128& operator/=(uint128 other);
uint128& operator%=(uint128 other);
uint128 operator++(int);
uint128 operator--(int);
uint128& operator<<=(int);
uint128& operator>>=(int);
uint128& operator&=(uint128 other);
uint128& operator|=(uint128 other);
uint128& operator^=(uint128 other);
uint128& operator++();
uint128& operator--();
// Uint128Low64()
//
// Returns the lower 64-bit value of a `uint128` value.
friend constexpr uint64_t Uint128Low64(uint128 v);
// Uint128High64()
//
// Returns the higher 64-bit value of a `uint128` value.
friend constexpr uint64_t Uint128High64(uint128 v);
// MakeUInt128()
//
// Constructs a `uint128` numeric value from two 64-bit unsigned integers.
// Note that this factory function is the only way to construct a `uint128`
// from integer values greater than 2^64.
//
// Example:
//
// absl::uint128 big = absl::MakeUint128(1, 0);
friend constexpr uint128 MakeUint128(uint64_t high, uint64_t low);
// Uint128Max()
//
// Returns the highest value for a 128-bit unsigned integer.
friend constexpr uint128 Uint128Max();
private:
constexpr uint128(uint64_t high, uint64_t low);
// TODO(strel) Update implementation to use __int128 once all users of
// uint128 are fixed to not depend on alignof(uint128) == 8. Also add
// alignas(16) to class definition to keep alignment consistent across
// platforms.
#if defined(ABSL_IS_LITTLE_ENDIAN)
uint64_t lo_;
uint64_t hi_;
#elif defined(ABSL_IS_BIG_ENDIAN)
uint64_t hi_;
uint64_t lo_;
#else // byte order
#error "Unsupported byte order: must be little-endian or big-endian."
#endif // byte order
};
// Prefer to use the constexpr `Uint128Max()`.
//
// TODO(absl-team) deprecate kuint128max once migration tool is released.
extern const uint128 kuint128max;
// allow uint128 to be logged
std::ostream& operator<<(std::ostream& os, uint128 v);
// TODO(strel) add operator>>(std::istream&, uint128)
// TODO(absl-team): Implement signed 128-bit type
// --------------------------------------------------------------------------
// Implementation details follow
// --------------------------------------------------------------------------
constexpr uint128 MakeUint128(uint64_t high, uint64_t low) {
return uint128(high, low);
}
constexpr uint128 Uint128Max() {
return uint128(std::numeric_limits<uint64_t>::max(),
std::numeric_limits<uint64_t>::max());
}
// Assignment from integer types.
inline uint128& uint128::operator=(int v) { return *this = uint128(v); }
inline uint128& uint128::operator=(unsigned int v) {
return *this = uint128(v);
}
inline uint128& uint128::operator=(long v) { // NOLINT(runtime/int)
return *this = uint128(v);
}
// NOLINTNEXTLINE(runtime/int)
inline uint128& uint128::operator=(unsigned long v) {
return *this = uint128(v);
}
// NOLINTNEXTLINE(runtime/int)
inline uint128& uint128::operator=(long long v) {
return *this = uint128(v);
}
// NOLINTNEXTLINE(runtime/int)
inline uint128& uint128::operator=(unsigned long long v) {
return *this = uint128(v);
}
#ifdef ABSL_HAVE_INTRINSIC_INT128
inline uint128& uint128::operator=(__int128 v) {
return *this = uint128(v);
}
inline uint128& uint128::operator=(unsigned __int128 v) {
return *this = uint128(v);
}
#endif // ABSL_HAVE_INTRINSIC_INT128
// Arithmetic operators.
uint128 operator<<(uint128 lhs, int amount);
uint128 operator>>(uint128 lhs, int amount);
uint128 operator+(uint128 lhs, uint128 rhs);
uint128 operator-(uint128 lhs, uint128 rhs);
uint128 operator*(uint128 lhs, uint128 rhs);
uint128 operator/(uint128 lhs, uint128 rhs);
uint128 operator%(uint128 lhs, uint128 rhs);
inline uint128& uint128::operator<<=(int amount) {
*this = *this << amount;
return *this;
}
inline uint128& uint128::operator>>=(int amount) {
*this = *this >> amount;
return *this;
}
inline uint128& uint128::operator+=(uint128 other) {
*this = *this + other;
return *this;
}
inline uint128& uint128::operator-=(uint128 other) {
*this = *this - other;
return *this;
}
inline uint128& uint128::operator*=(uint128 other) {
*this = *this * other;
return *this;
}
inline uint128& uint128::operator/=(uint128 other) {
*this = *this / other;
return *this;
}
inline uint128& uint128::operator%=(uint128 other) {
*this = *this % other;
return *this;
}
constexpr uint64_t Uint128Low64(uint128 v) { return v.lo_; }
constexpr uint64_t Uint128High64(uint128 v) { return v.hi_; }
// Constructors from integer types.
#if defined(ABSL_IS_LITTLE_ENDIAN)
constexpr uint128::uint128(uint64_t high, uint64_t low)
: lo_{low}, hi_{high} {}
constexpr uint128::uint128(int v)
: lo_{static_cast<uint64_t>(v)},
hi_{v < 0 ? std::numeric_limits<uint64_t>::max() : 0} {}
constexpr uint128::uint128(long v) // NOLINT(runtime/int)
: lo_{static_cast<uint64_t>(v)},
hi_{v < 0 ? std::numeric_limits<uint64_t>::max() : 0} {}
constexpr uint128::uint128(long long v) // NOLINT(runtime/int)
: lo_{static_cast<uint64_t>(v)},
hi_{v < 0 ? std::numeric_limits<uint64_t>::max() : 0} {}
constexpr uint128::uint128(unsigned int v) : lo_{v}, hi_{0} {}
// NOLINTNEXTLINE(runtime/int)
constexpr uint128::uint128(unsigned long v) : lo_{v}, hi_{0} {}
// NOLINTNEXTLINE(runtime/int)
constexpr uint128::uint128(unsigned long long v) : lo_{v}, hi_{0} {}
#ifdef ABSL_HAVE_INTRINSIC_INT128
constexpr uint128::uint128(__int128 v)
: lo_{static_cast<uint64_t>(v & ~uint64_t{0})},
hi_{static_cast<uint64_t>(static_cast<unsigned __int128>(v) >> 64)} {}
constexpr uint128::uint128(unsigned __int128 v)
: lo_{static_cast<uint64_t>(v & ~uint64_t{0})},
hi_{static_cast<uint64_t>(v >> 64)} {}
#endif // ABSL_HAVE_INTRINSIC_INT128
#elif defined(ABSL_IS_BIG_ENDIAN)
constexpr uint128::uint128(uint64_t high, uint64_t low)
: hi_{high}, lo_{low} {}
constexpr uint128::uint128(int v)
: hi_{v < 0 ? std::numeric_limits<uint64_t>::max() : 0},
lo_{static_cast<uint64_t>(v)} {}
constexpr uint128::uint128(long v) // NOLINT(runtime/int)
: hi_{v < 0 ? std::numeric_limits<uint64_t>::max() : 0},
lo_{static_cast<uint64_t>(v)} {}
constexpr uint128::uint128(long long v) // NOLINT(runtime/int)
: hi_{v < 0 ? std::numeric_limits<uint64_t>::max() : 0},
lo_{static_cast<uint64_t>(v)} {}
constexpr uint128::uint128(unsigned int v) : hi_{0}, lo_{v} {}
// NOLINTNEXTLINE(runtime/int)
constexpr uint128::uint128(unsigned long v) : hi_{0}, lo_{v} {}
// NOLINTNEXTLINE(runtime/int)
constexpr uint128::uint128(unsigned long long v) : hi_{0}, lo_{v} {}
#ifdef ABSL_HAVE_INTRINSIC_INT128
constexpr uint128::uint128(__int128 v)
: hi_{static_cast<uint64_t>(static_cast<unsigned __int128>(v) >> 64)},
lo_{static_cast<uint64_t>(v & ~uint64_t{0})} {}
constexpr uint128::uint128(unsigned __int128 v)
: hi_{static_cast<uint64_t>(v >> 64)},
lo_{static_cast<uint64_t>(v & ~uint64_t{0})} {}
#endif // ABSL_HAVE_INTRINSIC_INT128
#else // byte order
#error "Unsupported byte order: must be little-endian or big-endian."
#endif // byte order
// Conversion operators to integer types.
constexpr uint128::operator bool() const { return lo_ || hi_; }
constexpr uint128::operator char() const { return static_cast<char>(lo_); }
constexpr uint128::operator signed char() const {
return static_cast<signed char>(lo_);
}
constexpr uint128::operator unsigned char() const {
return static_cast<unsigned char>(lo_);
}
constexpr uint128::operator char16_t() const {
return static_cast<char16_t>(lo_);
}
constexpr uint128::operator char32_t() const {
return static_cast<char32_t>(lo_);
}
constexpr uint128::operator wchar_t() const {
return static_cast<wchar_t>(lo_);
}
// NOLINTNEXTLINE(runtime/int)
constexpr uint128::operator short() const { return static_cast<short>(lo_); }
constexpr uint128::operator unsigned short() const { // NOLINT(runtime/int)
return static_cast<unsigned short>(lo_); // NOLINT(runtime/int)
}
constexpr uint128::operator int() const { return static_cast<int>(lo_); }
constexpr uint128::operator unsigned int() const {
return static_cast<unsigned int>(lo_);
}
// NOLINTNEXTLINE(runtime/int)
constexpr uint128::operator long() const { return static_cast<long>(lo_); }
constexpr uint128::operator unsigned long() const { // NOLINT(runtime/int)
return static_cast<unsigned long>(lo_); // NOLINT(runtime/int)
}
constexpr uint128::operator long long() const { // NOLINT(runtime/int)
return static_cast<long long>(lo_); // NOLINT(runtime/int)
}
constexpr uint128::operator unsigned long long() const { // NOLINT(runtime/int)
return static_cast<unsigned long long>(lo_); // NOLINT(runtime/int)
}
#ifdef ABSL_HAVE_INTRINSIC_INT128
constexpr uint128::operator __int128() const {
return (static_cast<__int128>(hi_) << 64) + lo_;
}
constexpr uint128::operator unsigned __int128() const {
return (static_cast<unsigned __int128>(hi_) << 64) + lo_;
}
#endif // ABSL_HAVE_INTRINSIC_INT128
// Conversion operators to floating point types.
inline uint128::operator float() const {
return static_cast<float>(lo_) + std::ldexp(static_cast<float>(hi_), 64);
}
inline uint128::operator double() const {
return static_cast<double>(lo_) + std::ldexp(static_cast<double>(hi_), 64);
}
inline uint128::operator long double() const {
return static_cast<long double>(lo_) +
std::ldexp(static_cast<long double>(hi_), 64);
}
// Comparison operators.
inline bool operator==(uint128 lhs, uint128 rhs) {
return (Uint128Low64(lhs) == Uint128Low64(rhs) &&
Uint128High64(lhs) == Uint128High64(rhs));
}
inline bool operator!=(uint128 lhs, uint128 rhs) {
return !(lhs == rhs);
}
inline bool operator<(uint128 lhs, uint128 rhs) {
return (Uint128High64(lhs) == Uint128High64(rhs))
? (Uint128Low64(lhs) < Uint128Low64(rhs))
: (Uint128High64(lhs) < Uint128High64(rhs));
}
inline bool operator>(uint128 lhs, uint128 rhs) {
return (Uint128High64(lhs) == Uint128High64(rhs))
? (Uint128Low64(lhs) > Uint128Low64(rhs))
: (Uint128High64(lhs) > Uint128High64(rhs));
}
inline bool operator<=(uint128 lhs, uint128 rhs) {
return (Uint128High64(lhs) == Uint128High64(rhs))
? (Uint128Low64(lhs) <= Uint128Low64(rhs))
: (Uint128High64(lhs) <= Uint128High64(rhs));
}
inline bool operator>=(uint128 lhs, uint128 rhs) {
return (Uint128High64(lhs) == Uint128High64(rhs))
? (Uint128Low64(lhs) >= Uint128Low64(rhs))
: (Uint128High64(lhs) >= Uint128High64(rhs));
}
// Unary operators.
inline uint128 operator-(uint128 val) {
uint64_t hi = ~Uint128High64(val);
uint64_t lo = ~Uint128Low64(val) + 1;
if (lo == 0) ++hi; // carry
return MakeUint128(hi, lo);
}
inline bool operator!(uint128 val) {
return !Uint128High64(val) && !Uint128Low64(val);
}
// Logical operators.
inline uint128 operator~(uint128 val) {
return MakeUint128(~Uint128High64(val), ~Uint128Low64(val));
}
inline uint128 operator|(uint128 lhs, uint128 rhs) {
return MakeUint128(Uint128High64(lhs) | Uint128High64(rhs),
Uint128Low64(lhs) | Uint128Low64(rhs));
}
inline uint128 operator&(uint128 lhs, uint128 rhs) {
return MakeUint128(Uint128High64(lhs) & Uint128High64(rhs),
Uint128Low64(lhs) & Uint128Low64(rhs));
}
inline uint128 operator^(uint128 lhs, uint128 rhs) {
return MakeUint128(Uint128High64(lhs) ^ Uint128High64(rhs),
Uint128Low64(lhs) ^ Uint128Low64(rhs));
}
inline uint128& uint128::operator|=(uint128 other) {
hi_ |= other.hi_;
lo_ |= other.lo_;
return *this;
}
inline uint128& uint128::operator&=(uint128 other) {
hi_ &= other.hi_;
lo_ &= other.lo_;
return *this;
}
inline uint128& uint128::operator^=(uint128 other) {
hi_ ^= other.hi_;
lo_ ^= other.lo_;
return *this;
}
// Arithmetic operators.
inline uint128 operator<<(uint128 lhs, int amount) {
// uint64_t shifts of >= 64 are undefined, so we will need some
// special-casing.
if (amount < 64) {
if (amount != 0) {
return MakeUint128(
(Uint128High64(lhs) << amount) | (Uint128Low64(lhs) >> (64 - amount)),
Uint128Low64(lhs) << amount);
}
return lhs;
}
return MakeUint128(Uint128Low64(lhs) << (amount - 64), 0);
}
inline uint128 operator>>(uint128 lhs, int amount) {
// uint64_t shifts of >= 64 are undefined, so we will need some
// special-casing.
if (amount < 64) {
if (amount != 0) {
return MakeUint128(Uint128High64(lhs) >> amount,
(Uint128Low64(lhs) >> amount) |
(Uint128High64(lhs) << (64 - amount)));
}
return lhs;
}
return MakeUint128(0, Uint128High64(lhs) >> (amount - 64));
}
inline uint128 operator+(uint128 lhs, uint128 rhs) {
uint128 result = MakeUint128(Uint128High64(lhs) + Uint128High64(rhs),
Uint128Low64(lhs) + Uint128Low64(rhs));
if (Uint128Low64(result) < Uint128Low64(lhs)) { // check for carry
return MakeUint128(Uint128High64(result) + 1, Uint128Low64(result));
}
return result;
}
inline uint128 operator-(uint128 lhs, uint128 rhs) {
uint128 result = MakeUint128(Uint128High64(lhs) - Uint128High64(rhs),
Uint128Low64(lhs) - Uint128Low64(rhs));
if (Uint128Low64(lhs) < Uint128Low64(rhs)) { // check for carry
return MakeUint128(Uint128High64(result) - 1, Uint128Low64(result));
}
return result;
}
inline uint128 operator*(uint128 lhs, uint128 rhs) {
#if defined(ABSL_HAVE_INTRINSIC_INT128)
// TODO(strel) Remove once alignment issues are resolved and unsigned __int128
// can be used for uint128 storage.
return static_cast<unsigned __int128>(lhs) *
static_cast<unsigned __int128>(rhs);
#else // ABSL_HAVE_INTRINSIC128
uint64_t a32 = Uint128Low64(lhs) >> 32;
uint64_t a00 = Uint128Low64(lhs) & 0xffffffff;
uint64_t b32 = Uint128Low64(rhs) >> 32;
uint64_t b00 = Uint128Low64(rhs) & 0xffffffff;
uint128 result =
MakeUint128(Uint128High64(lhs) * Uint128Low64(rhs) +
Uint128Low64(lhs) * Uint128High64(rhs) + a32 * b32,
a00 * b00);
result += uint128(a32 * b00) << 32;
result += uint128(a00 * b32) << 32;
return result;
#endif // ABSL_HAVE_INTRINSIC128
}
// Increment/decrement operators.
inline uint128 uint128::operator++(int) {
uint128 tmp(*this);
*this += 1;
return tmp;
}
inline uint128 uint128::operator--(int) {
uint128 tmp(*this);
*this -= 1;
return tmp;
}
inline uint128& uint128::operator++() {
*this += 1;
return *this;
}
inline uint128& uint128::operator--() {
*this -= 1;
return *this;
}
#if defined(ABSL_HAVE_INTRINSIC_INT128)
#include "absl/numeric/int128_have_intrinsic.inc"
#else // ABSL_HAVE_INTRINSIC_INT128
#include "absl/numeric/int128_no_intrinsic.inc"
#endif // ABSL_HAVE_INTRINSIC_INT128
} // namespace absl
#endif // ABSL_NUMERIC_INT128_H_