diff --git a/absl/numeric/int128.h b/absl/numeric/int128.h
new file mode 100644
index 0000000..10be8ec
--- /dev/null
+++ b/absl/numeric/int128.h
@@ -0,0 +1,732 @@
+//
+// 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
+//
+//      https://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 <utility>
+
+#include "absl/base/config.h"
+#include "absl/base/macros.h"
+#include "absl/base/port.h"
+
+#if defined(_MSC_VER)
+// In very old versions of MSVC and when the /Zc:wchar_t flag is off, wchar_t is
+// a typedef for unsigned short.  Otherwise wchar_t is mapped to the __wchar_t
+// builtin type.  We need to make sure not to define operator wchar_t()
+// alongside operator unsigned short() in these instances.
+#define ABSL_INTERNAL_WCHAR_T __wchar_t
+#if defined(_M_X64)
+#include <intrin.h>
+#pragma intrinsic(_umul128)
+#endif  // defined(_M_X64)
+#else   // defined(_MSC_VER)
+#define ABSL_INTERNAL_WCHAR_T wchar_t
+#endif  // defined(_MSC_VER)
+
+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;
+//     uint64_t i = v;                         // Error
+//     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 ABSL_INTERNAL_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();
+
+  // Support for absl::Hash.
+  template <typename H>
+  friend H AbslHashValue(H h, uint128 v) {
+    return H::combine(std::move(h), Uint128High64(v), Uint128Low64(v));
+  }
+
+ 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)
+
+constexpr uint128 Uint128Max() {
+  return uint128((std::numeric_limits<uint64_t>::max)(),
+                 (std::numeric_limits<uint64_t>::max)());
+}
+
+}  // namespace absl
+
+// Specialized numeric_limits for uint128.
+namespace std {
+template <>
+class numeric_limits<absl::uint128> {
+ public:
+  static constexpr bool is_specialized = true;
+  static constexpr bool is_signed = false;
+  static constexpr bool is_integer = true;
+  static constexpr bool is_exact = true;
+  static constexpr bool has_infinity = false;
+  static constexpr bool has_quiet_NaN = false;
+  static constexpr bool has_signaling_NaN = false;
+  static constexpr float_denorm_style has_denorm = denorm_absent;
+  static constexpr bool has_denorm_loss = false;
+  static constexpr float_round_style round_style = round_toward_zero;
+  static constexpr bool is_iec559 = false;
+  static constexpr bool is_bounded = true;
+  static constexpr bool is_modulo = true;
+  static constexpr int digits = 128;
+  static constexpr int digits10 = 38;
+  static constexpr int max_digits10 = 0;
+  static constexpr int radix = 2;
+  static constexpr int min_exponent = 0;
+  static constexpr int min_exponent10 = 0;
+  static constexpr int max_exponent = 0;
+  static constexpr int max_exponent10 = 0;
+#ifdef ABSL_HAVE_INTRINSIC_INT128
+  static constexpr bool traps = numeric_limits<unsigned __int128>::traps;
+#else   // ABSL_HAVE_INTRINSIC_INT128
+  static constexpr bool traps = numeric_limits<uint64_t>::traps;
+#endif  // ABSL_HAVE_INTRINSIC_INT128
+  static constexpr bool tinyness_before = false;
+
+  static constexpr absl::uint128 (min)() { return 0; }
+  static constexpr absl::uint128 lowest() { return 0; }
+  static constexpr absl::uint128 (max)() { return absl::Uint128Max(); }
+  static constexpr absl::uint128 epsilon() { return 0; }
+  static constexpr absl::uint128 round_error() { return 0; }
+  static constexpr absl::uint128 infinity() { return 0; }
+  static constexpr absl::uint128 quiet_NaN() { return 0; }
+  static constexpr absl::uint128 signaling_NaN() { return 0; }
+  static constexpr absl::uint128 denorm_min() { return 0; }
+};
+}  // namespace std
+
+// TODO(absl-team): Implement signed 128-bit type
+
+// --------------------------------------------------------------------------
+//                      Implementation details follow
+// --------------------------------------------------------------------------
+namespace absl {
+
+constexpr uint128 MakeUint128(uint64_t high, uint64_t low) {
+  return uint128(high, low);
+}
+
+// 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 ABSL_INTERNAL_WCHAR_T() const {
+  return static_cast<ABSL_INTERNAL_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);
+#elif defined(_MSC_VER) && defined(_M_X64)
+  uint64_t carry;
+  uint64_t low = _umul128(Uint128Low64(lhs), Uint128Low64(rhs), &carry);
+  return MakeUint128(Uint128Low64(lhs) * Uint128High64(rhs) +
+                         Uint128High64(lhs) * Uint128Low64(rhs) + carry,
+                     low);
+#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
+
+#undef ABSL_INTERNAL_WCHAR_T
+
+#endif  // ABSL_NUMERIC_INT128_H_