1b8dacca62
- 536d004b7e2d48927a5f82e71e9e3a0a9afedbc8 Change uint128 parameters to pass by value. by Alex Strelnikov <strel@google.com> GitOrigin-RevId: 536d004b7e2d48927a5f82e71e9e3a0a9afedbc8 Change-Id: I9c5e73ce06c8423a27ec7bff2c4accc434e99cb2
632 lines
19 KiB
C++
632 lines
19 KiB
C++
//
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// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// -----------------------------------------------------------------------------
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// File: int128.h
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// -----------------------------------------------------------------------------
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//
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// This header file defines 128-bit integer types. Currently, this file defines
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// `uint128`, an unsigned 128-bit integer; a signed 128-bit integer is
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// forthcoming.
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#ifndef ABSL_NUMERIC_INT128_H_
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#define ABSL_NUMERIC_INT128_H_
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#include <cassert>
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#include <cmath>
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#include <cstdint>
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#include <cstring>
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#include <iosfwd>
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#include <limits>
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#include "absl/base/config.h"
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#include "absl/base/macros.h"
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#include "absl/base/port.h"
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namespace absl {
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// uint128
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//
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// An unsigned 128-bit integer type. The API is meant to mimic an intrinsic type
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// as closely as is practical, including exhibiting undefined behavior in
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// analogous cases (e.g. division by zero). This type is intended to be a
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// drop-in replacement once C++ supports an intrinsic `uint128_t` type; when
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// that occurs, existing uses of `uint128` will continue to work using that new
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// type.
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//
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// Note: code written with this type will continue to compile once `uint128_t`
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// is introduced, provided the replacement helper functions
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// `Uint128(Low|High)64()` and `MakeUint128()` are made.
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//
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// A `uint128` supports the following:
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//
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// * Implicit construction from integral types
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// * Explicit conversion to integral types
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//
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// Additionally, if your compiler supports `__int128`, `uint128` is
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// interoperable with that type. (Abseil checks for this compatibility through
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// the `ABSL_HAVE_INTRINSIC_INT128` macro.)
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//
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// However, a `uint128` differs from intrinsic integral types in the following
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// ways:
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//
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// * Errors on implicit conversions that does not preserve value (such as
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// loss of precision when converting to float values).
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// * Requires explicit construction from and conversion to floating point
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// types.
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// * Conversion to integral types requires an explicit static_cast() to
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// mimic use of the `-Wnarrowing` compiler flag.
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//
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// Example:
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//
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// float y = absl::kuint128max; // Error. uint128 cannot be implicitly
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// // converted to float.
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//
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// absl::uint128 v;
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// absl::uint64_t i = v; // Error
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// absl::uint64_t i = static_cast<uint64_t>(v); // OK
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//
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class alignas(16) uint128 {
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public:
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uint128() = default;
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// Constructors from arithmetic types
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constexpr uint128(int v); // NOLINT(runtime/explicit)
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constexpr uint128(unsigned int v); // NOLINT(runtime/explicit)
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constexpr uint128(long v); // NOLINT(runtime/int)
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constexpr uint128(unsigned long v); // NOLINT(runtime/int)
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constexpr uint128(long long v); // NOLINT(runtime/int)
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constexpr uint128(unsigned long long v); // NOLINT(runtime/int)
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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constexpr uint128(__int128 v); // NOLINT(runtime/explicit)
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constexpr uint128(unsigned __int128 v); // NOLINT(runtime/explicit)
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#endif // ABSL_HAVE_INTRINSIC_INT128
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explicit uint128(float v);
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explicit uint128(double v);
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explicit uint128(long double v);
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// Assignment operators from arithmetic types
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uint128& operator=(int v);
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uint128& operator=(unsigned int v);
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uint128& operator=(long v); // NOLINT(runtime/int)
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uint128& operator=(unsigned long v); // NOLINT(runtime/int)
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uint128& operator=(long long v); // NOLINT(runtime/int)
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uint128& operator=(unsigned long long v); // NOLINT(runtime/int)
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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uint128& operator=(__int128 v);
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uint128& operator=(unsigned __int128 v);
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#endif // ABSL_HAVE_INTRINSIC_INT128
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// Conversion operators to other arithmetic types
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constexpr explicit operator bool() const;
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constexpr explicit operator char() const;
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constexpr explicit operator signed char() const;
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constexpr explicit operator unsigned char() const;
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constexpr explicit operator char16_t() const;
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constexpr explicit operator char32_t() const;
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constexpr explicit operator wchar_t() const;
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constexpr explicit operator short() const; // NOLINT(runtime/int)
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// NOLINTNEXTLINE(runtime/int)
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constexpr explicit operator unsigned short() const;
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constexpr explicit operator int() const;
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constexpr explicit operator unsigned int() const;
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constexpr explicit operator long() const; // NOLINT(runtime/int)
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// NOLINTNEXTLINE(runtime/int)
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constexpr explicit operator unsigned long() const;
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// NOLINTNEXTLINE(runtime/int)
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constexpr explicit operator long long() const;
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// NOLINTNEXTLINE(runtime/int)
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constexpr explicit operator unsigned long long() const;
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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constexpr explicit operator __int128() const;
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constexpr explicit operator unsigned __int128() const;
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#endif // ABSL_HAVE_INTRINSIC_INT128
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explicit operator float() const;
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explicit operator double() const;
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explicit operator long double() const;
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// Trivial copy constructor, assignment operator and destructor.
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// Arithmetic operators.
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uint128& operator+=(uint128 other);
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uint128& operator-=(uint128 other);
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uint128& operator*=(uint128 other);
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// Long division/modulo for uint128.
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uint128& operator/=(uint128 other);
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uint128& operator%=(uint128 other);
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uint128 operator++(int);
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uint128 operator--(int);
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uint128& operator<<=(int);
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uint128& operator>>=(int);
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uint128& operator&=(uint128 other);
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uint128& operator|=(uint128 other);
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uint128& operator^=(uint128 other);
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uint128& operator++();
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uint128& operator--();
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// Uint128Low64()
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//
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// Returns the lower 64-bit value of a `uint128` value.
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friend constexpr uint64_t Uint128Low64(uint128 v);
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// Uint128High64()
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//
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// Returns the higher 64-bit value of a `uint128` value.
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friend constexpr uint64_t Uint128High64(uint128 v);
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// MakeUInt128()
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//
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// Constructs a `uint128` numeric value from two 64-bit unsigned integers.
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// Note that this factory function is the only way to construct a `uint128`
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// from integer values greater than 2^64.
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//
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// Example:
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//
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// absl::uint128 big = absl::MakeUint128(1, 0);
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friend constexpr uint128 MakeUint128(uint64_t top, uint64_t bottom);
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private:
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constexpr uint128(uint64_t top, uint64_t bottom);
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// TODO(strel) Update implementation to use __int128 once all users of
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// uint128 are fixed to not depend on alignof(uint128) == 8. Also add
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// alignas(16) to class definition to keep alignment consistent across
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// platforms.
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#if defined(ABSL_IS_LITTLE_ENDIAN)
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uint64_t lo_;
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uint64_t hi_;
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#elif defined(ABSL_IS_BIG_ENDIAN)
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uint64_t hi_;
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uint64_t lo_;
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#else // byte order
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#error "Unsupported byte order: must be little-endian or big-endian."
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#endif // byte order
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};
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extern const uint128 kuint128max;
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// allow uint128 to be logged
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extern std::ostream& operator<<(std::ostream& o, uint128 b);
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// TODO(strel) add operator>>(std::istream&, uint128)
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// TODO(absl-team): Implement signed 128-bit type
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// --------------------------------------------------------------------------
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// Implementation details follow
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// --------------------------------------------------------------------------
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constexpr uint128 MakeUint128(uint64_t top, uint64_t bottom) {
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return uint128(top, bottom);
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}
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// Assignment from integer types.
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inline uint128& uint128::operator=(int v) { return *this = uint128(v); }
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inline uint128& uint128::operator=(unsigned int v) {
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return *this = uint128(v);
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}
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inline uint128& uint128::operator=(long v) { // NOLINT(runtime/int)
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return *this = uint128(v);
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}
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// NOLINTNEXTLINE(runtime/int)
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inline uint128& uint128::operator=(unsigned long v) {
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return *this = uint128(v);
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}
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// NOLINTNEXTLINE(runtime/int)
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inline uint128& uint128::operator=(long long v) {
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return *this = uint128(v);
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}
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// NOLINTNEXTLINE(runtime/int)
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inline uint128& uint128::operator=(unsigned long long v) {
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return *this = uint128(v);
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}
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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inline uint128& uint128::operator=(__int128 v) {
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return *this = uint128(v);
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}
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inline uint128& uint128::operator=(unsigned __int128 v) {
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return *this = uint128(v);
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}
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#endif // ABSL_HAVE_INTRINSIC_INT128
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// Shift and arithmetic operators.
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inline uint128 operator<<(uint128 lhs, int amount) {
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return uint128(lhs) <<= amount;
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}
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inline uint128 operator>>(uint128 lhs, int amount) {
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return uint128(lhs) >>= amount;
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}
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inline uint128 operator+(uint128 lhs, uint128 rhs) {
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return uint128(lhs) += rhs;
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}
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inline uint128 operator-(uint128 lhs, uint128 rhs) {
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return uint128(lhs) -= rhs;
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}
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inline uint128 operator*(uint128 lhs, uint128 rhs) {
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return uint128(lhs) *= rhs;
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}
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inline uint128 operator/(uint128 lhs, uint128 rhs) {
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return uint128(lhs) /= rhs;
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}
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inline uint128 operator%(uint128 lhs, uint128 rhs) {
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return uint128(lhs) %= rhs;
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}
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constexpr uint64_t Uint128Low64(uint128 v) { return v.lo_; }
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constexpr uint64_t Uint128High64(uint128 v) { return v.hi_; }
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// Constructors from integer types.
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#if defined(ABSL_IS_LITTLE_ENDIAN)
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constexpr uint128::uint128(uint64_t top, uint64_t bottom)
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: lo_(bottom), hi_(top) {}
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constexpr uint128::uint128(int v)
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: lo_(v), hi_(v < 0 ? std::numeric_limits<uint64_t>::max() : 0) {}
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constexpr uint128::uint128(long v) // NOLINT(runtime/int)
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: lo_(v), hi_(v < 0 ? std::numeric_limits<uint64_t>::max() : 0) {}
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constexpr uint128::uint128(long long v) // NOLINT(runtime/int)
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: lo_(v), hi_(v < 0 ? std::numeric_limits<uint64_t>::max() : 0) {}
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constexpr uint128::uint128(unsigned int v) : lo_(v), hi_(0) {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr uint128::uint128(unsigned long v) : lo_(v), hi_(0) {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr uint128::uint128(unsigned long long v) : lo_(v), hi_(0) {}
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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constexpr uint128::uint128(__int128 v)
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: lo_(static_cast<uint64_t>(v & ~uint64_t{0})),
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hi_(static_cast<uint64_t>(static_cast<unsigned __int128>(v) >> 64)) {}
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constexpr uint128::uint128(unsigned __int128 v)
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: lo_(static_cast<uint64_t>(v & ~uint64_t{0})),
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hi_(static_cast<uint64_t>(v >> 64)) {}
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#endif // ABSL_HAVE_INTRINSIC_INT128
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#elif defined(ABSL_IS_BIG_ENDIAN)
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constexpr uint128::uint128(uint64_t top, uint64_t bottom)
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: hi_(top), lo_(bottom) {}
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constexpr uint128::uint128(int v)
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: hi_(v < 0 ? std::numeric_limits<uint64_t>::max() : 0), lo_(v) {}
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constexpr uint128::uint128(long v) // NOLINT(runtime/int)
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: hi_(v < 0 ? std::numeric_limits<uint64_t>::max() : 0), lo_(v) {}
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constexpr uint128::uint128(long long v) // NOLINT(runtime/int)
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: hi_(v < 0 ? std::numeric_limits<uint64_t>::max() : 0), lo_(v) {}
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constexpr uint128::uint128(unsigned int v) : hi_(0), lo_(v) {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr uint128::uint128(unsigned long v) : hi_(0), lo_(v) {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr uint128::uint128(unsigned long long v) : hi_(0), lo_(v) {}
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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constexpr uint128::uint128(__int128 v)
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: hi_(static_cast<uint64_t>(static_cast<unsigned __int128>(v) >> 64)),
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lo_(static_cast<uint64_t>(v & ~uint64_t{0})) {}
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constexpr uint128::uint128(unsigned __int128 v)
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: hi_(static_cast<uint64_t>(v >> 64)),
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lo_(static_cast<uint64_t>(v & ~uint64_t{0})) {}
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#endif // ABSL_HAVE_INTRINSIC_INT128
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#else // byte order
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#error "Unsupported byte order: must be little-endian or big-endian."
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#endif // byte order
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// Conversion operators to integer types.
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constexpr uint128::operator bool() const { return lo_ || hi_; }
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constexpr uint128::operator char() const { return static_cast<char>(lo_); }
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constexpr uint128::operator signed char() const {
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return static_cast<signed char>(lo_);
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}
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constexpr uint128::operator unsigned char() const {
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return static_cast<unsigned char>(lo_);
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}
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constexpr uint128::operator char16_t() const {
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return static_cast<char16_t>(lo_);
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}
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constexpr uint128::operator char32_t() const {
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return static_cast<char32_t>(lo_);
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}
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constexpr uint128::operator wchar_t() const {
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return static_cast<wchar_t>(lo_);
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}
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// NOLINTNEXTLINE(runtime/int)
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constexpr uint128::operator short() const { return static_cast<short>(lo_); }
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constexpr uint128::operator unsigned short() const { // NOLINT(runtime/int)
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return static_cast<unsigned short>(lo_); // NOLINT(runtime/int)
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}
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constexpr uint128::operator int() const { return static_cast<int>(lo_); }
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constexpr uint128::operator unsigned int() const {
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return static_cast<unsigned int>(lo_);
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}
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// NOLINTNEXTLINE(runtime/int)
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constexpr uint128::operator long() const { return static_cast<long>(lo_); }
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constexpr uint128::operator unsigned long() const { // NOLINT(runtime/int)
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return static_cast<unsigned long>(lo_); // NOLINT(runtime/int)
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}
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constexpr uint128::operator long long() const { // NOLINT(runtime/int)
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return static_cast<long long>(lo_); // NOLINT(runtime/int)
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}
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constexpr uint128::operator unsigned long long() const { // NOLINT(runtime/int)
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return static_cast<unsigned long long>(lo_); // NOLINT(runtime/int)
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}
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#ifdef ABSL_HAVE_INTRINSIC_INT128
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constexpr uint128::operator __int128() const {
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return (static_cast<__int128>(hi_) << 64) + lo_;
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}
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constexpr uint128::operator unsigned __int128() const {
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return (static_cast<unsigned __int128>(hi_) << 64) + lo_;
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}
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#endif // ABSL_HAVE_INTRINSIC_INT128
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// Conversion operators to floating point types.
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inline uint128::operator float() const {
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return static_cast<float>(lo_) + std::ldexp(static_cast<float>(hi_), 64);
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}
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inline uint128::operator double() const {
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return static_cast<double>(lo_) + std::ldexp(static_cast<double>(hi_), 64);
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}
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inline uint128::operator long double() const {
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return static_cast<long double>(lo_) +
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std::ldexp(static_cast<long double>(hi_), 64);
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}
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// Comparison operators.
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inline bool operator==(uint128 lhs, uint128 rhs) {
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return (Uint128Low64(lhs) == Uint128Low64(rhs) &&
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Uint128High64(lhs) == Uint128High64(rhs));
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}
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inline bool operator!=(uint128 lhs, uint128 rhs) {
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return !(lhs == rhs);
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}
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inline bool operator<(uint128 lhs, uint128 rhs) {
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return (Uint128High64(lhs) == Uint128High64(rhs))
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? (Uint128Low64(lhs) < Uint128Low64(rhs))
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: (Uint128High64(lhs) < Uint128High64(rhs));
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}
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inline bool operator>(uint128 lhs, uint128 rhs) {
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return (Uint128High64(lhs) == Uint128High64(rhs))
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? (Uint128Low64(lhs) > Uint128Low64(rhs))
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: (Uint128High64(lhs) > Uint128High64(rhs));
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}
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inline bool operator<=(uint128 lhs, uint128 rhs) {
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return (Uint128High64(lhs) == Uint128High64(rhs))
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? (Uint128Low64(lhs) <= Uint128Low64(rhs))
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: (Uint128High64(lhs) <= Uint128High64(rhs));
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}
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inline bool operator>=(uint128 lhs, uint128 rhs) {
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return (Uint128High64(lhs) == Uint128High64(rhs))
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? (Uint128Low64(lhs) >= Uint128Low64(rhs))
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: (Uint128High64(lhs) >= Uint128High64(rhs));
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}
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// Unary operators.
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inline uint128 operator-(uint128 val) {
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const uint64_t hi_flip = ~Uint128High64(val);
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const uint64_t lo_flip = ~Uint128Low64(val);
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const uint64_t lo_add = lo_flip + 1;
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if (lo_add < lo_flip) {
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return MakeUint128(hi_flip + 1, lo_add);
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}
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return MakeUint128(hi_flip, lo_add);
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}
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inline bool operator!(uint128 val) {
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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;
|
|
}
|
|
|
|
// Shift and arithmetic assign operators.
|
|
|
|
inline uint128& uint128::operator<<=(int amount) {
|
|
// Shifts of >= 128 are undefined.
|
|
assert(amount < 128);
|
|
|
|
// uint64_t shifts of >= 64 are undefined, so we will need some
|
|
// special-casing.
|
|
if (amount < 64) {
|
|
if (amount != 0) {
|
|
hi_ = (hi_ << amount) | (lo_ >> (64 - amount));
|
|
lo_ = lo_ << amount;
|
|
}
|
|
} else {
|
|
hi_ = lo_ << (amount - 64);
|
|
lo_ = 0;
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
inline uint128& uint128::operator>>=(int amount) {
|
|
// Shifts of >= 128 are undefined.
|
|
assert(amount < 128);
|
|
|
|
// uint64_t shifts of >= 64 are undefined, so we will need some
|
|
// special-casing.
|
|
if (amount < 64) {
|
|
if (amount != 0) {
|
|
lo_ = (lo_ >> amount) | (hi_ << (64 - amount));
|
|
hi_ = hi_ >> amount;
|
|
}
|
|
} else {
|
|
lo_ = hi_ >> (amount - 64);
|
|
hi_ = 0;
|
|
}
|
|
return *this;
|
|
}
|
|
|
|
inline uint128& uint128::operator+=(uint128 other) {
|
|
hi_ += other.hi_;
|
|
uint64_t lolo = lo_ + other.lo_;
|
|
if (lolo < lo_)
|
|
++hi_;
|
|
lo_ = lolo;
|
|
return *this;
|
|
}
|
|
|
|
inline uint128& uint128::operator-=(uint128 other) {
|
|
hi_ -= other.hi_;
|
|
if (other.lo_ > lo_) --hi_;
|
|
lo_ -= other.lo_;
|
|
return *this;
|
|
}
|
|
|
|
inline uint128& uint128::operator*=(uint128 other) {
|
|
#if defined(ABSL_HAVE_INTRINSIC_INT128)
|
|
// TODO(strel) Remove once alignment issues are resolved and unsigned __int128
|
|
// can be used for uint128 storage.
|
|
*this = static_cast<unsigned __int128>(*this) *
|
|
static_cast<unsigned __int128>(other);
|
|
return *this;
|
|
#else // ABSL_HAVE_INTRINSIC128
|
|
uint64_t a96 = hi_ >> 32;
|
|
uint64_t a64 = hi_ & 0xffffffff;
|
|
uint64_t a32 = lo_ >> 32;
|
|
uint64_t a00 = lo_ & 0xffffffff;
|
|
uint64_t b96 = other.hi_ >> 32;
|
|
uint64_t b64 = other.hi_ & 0xffffffff;
|
|
uint64_t b32 = other.lo_ >> 32;
|
|
uint64_t b00 = other.lo_ & 0xffffffff;
|
|
// multiply [a96 .. a00] x [b96 .. b00]
|
|
// terms higher than c96 disappear off the high side
|
|
// terms c96 and c64 are safe to ignore carry bit
|
|
uint64_t c96 = a96 * b00 + a64 * b32 + a32 * b64 + a00 * b96;
|
|
uint64_t c64 = a64 * b00 + a32 * b32 + a00 * b64;
|
|
this->hi_ = (c96 << 32) + c64;
|
|
this->lo_ = 0;
|
|
// add terms after this one at a time to capture carry
|
|
*this += uint128(a32 * b00) << 32;
|
|
*this += uint128(a00 * b32) << 32;
|
|
*this += a00 * b00;
|
|
return *this;
|
|
#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_
|