diff options
Diffstat (limited to 'absl/numeric/int128.h')
| -rw-r--r-- | absl/numeric/int128.h | 363 |
1 files changed, 358 insertions, 5 deletions
diff --git a/absl/numeric/int128.h b/absl/numeric/int128.h index 4f965686c393..506176127fe6 100644 --- a/absl/numeric/int128.h +++ b/absl/numeric/int128.h @@ -17,10 +17,7 @@ // 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. +// This header file defines 128-bit integer types, `uint128` and `int128`. #ifndef ABSL_NUMERIC_INT128_H_ #define ABSL_NUMERIC_INT128_H_ @@ -53,6 +50,8 @@ namespace absl { +class int128; + // uint128 // // An unsigned 128-bit integer type. The API is meant to mimic an intrinsic type @@ -116,6 +115,7 @@ class constexpr uint128(__int128 v); // NOLINT(runtime/explicit) constexpr uint128(unsigned __int128 v); // NOLINT(runtime/explicit) #endif // ABSL_HAVE_INTRINSIC_INT128 + constexpr uint128(int128 v); // NOLINT(runtime/explicit) explicit uint128(float v); explicit uint128(double v); explicit uint128(long double v); @@ -131,6 +131,7 @@ class uint128& operator=(__int128 v); uint128& operator=(unsigned __int128 v); #endif // ABSL_HAVE_INTRINSIC_INT128 + uint128& operator=(int128 v); // Conversion operators to other arithmetic types constexpr explicit operator bool() const; @@ -291,7 +292,238 @@ class numeric_limits<absl::uint128> { }; } // namespace std -// TODO(absl-team): Implement signed 128-bit type +namespace absl { + +// int128 +// +// A signed 128-bit integer type. The API is meant to mimic an intrinsic +// integral type as closely as is practical, including exhibiting undefined +// behavior in analogous cases (e.g. division by zero). +// +// An `int128` supports the following: +// +// * Implicit construction from integral types +// * Explicit conversion to integral types +// +// However, an `int128` differs from intrinsic integral types in the following +// ways: +// +// * It is not implicitly convertible to other integral types. +// * Requires explicit construction from and conversion to floating point +// types. + +// Additionally, if your compiler supports `__int128`, `int128` is +// interoperable with that type. (Abseil checks for this compatibility through +// the `ABSL_HAVE_INTRINSIC_INT128` macro.) +// +// The design goal for `int128` is that it will be compatible with a future +// `int128_t`, if that type becomes a part of the standard. +// +// Example: +// +// float y = absl::int128(17); // Error. int128 cannot be implicitly +// // converted to float. +// +// absl::int128 v; +// int64_t i = v; // Error +// int64_t i = static_cast<int64_t>(v); // OK +// +class int128 { + public: + int128() = default; + + // Constructors from arithmetic types + constexpr int128(int v); // NOLINT(runtime/explicit) + constexpr int128(unsigned int v); // NOLINT(runtime/explicit) + constexpr int128(long v); // NOLINT(runtime/int) + constexpr int128(unsigned long v); // NOLINT(runtime/int) + constexpr int128(long long v); // NOLINT(runtime/int) + constexpr int128(unsigned long long v); // NOLINT(runtime/int) +#ifdef ABSL_HAVE_INTRINSIC_INT128 + constexpr int128(__int128 v); // NOLINT(runtime/explicit) + constexpr explicit int128(unsigned __int128 v); +#endif // ABSL_HAVE_INTRINSIC_INT128 + constexpr explicit int128(uint128 v); + explicit int128(float v); + explicit int128(double v); + explicit int128(long double v); + + // Assignment operators from arithmetic types + int128& operator=(int v); + int128& operator=(unsigned int v); + int128& operator=(long v); // NOLINT(runtime/int) + int128& operator=(unsigned long v); // NOLINT(runtime/int) + int128& operator=(long long v); // NOLINT(runtime/int) + int128& operator=(unsigned long long v); // NOLINT(runtime/int) +#ifdef ABSL_HAVE_INTRINSIC_INT128 + int128& operator=(__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 + int128& operator+=(int128 other); + int128& operator-=(int128 other); + int128& operator*=(int128 other); + int128& operator/=(int128 other); + int128& operator%=(int128 other); + int128 operator++(int); // postfix increment: i++ + int128 operator--(int); // postfix decrement: i-- + int128& operator++(); // prefix increment: ++i + int128& operator--(); // prefix decrement: --i + int128& operator&=(int128 other); + int128& operator|=(int128 other); + int128& operator^=(int128 other); + int128& operator<<=(int amount); + int128& operator>>=(int amount); + + // Int128Low64() + // + // Returns the lower 64-bit value of a `int128` value. + friend constexpr uint64_t Int128Low64(int128 v); + + // Int128High64() + // + // Returns the higher 64-bit value of a `int128` value. + friend constexpr int64_t Int128High64(int128 v); + + // MakeInt128() + // + // Constructs a `int128` numeric value from two 64-bit integers. Note that + // signedness is conveyed in the upper `high` value. + // + // (absl::int128(1) << 64) * high + low + // + // Note that this factory function is the only way to construct a `int128` + // from integer values greater than 2^64 or less than -2^64. + // + // Example: + // + // absl::int128 big = absl::MakeInt128(1, 0); + // absl::int128 big_n = absl::MakeInt128(-1, 0); + friend constexpr int128 MakeInt128(int64_t high, uint64_t low); + + // Int128Max() + // + // Returns the maximum value for a 128-bit signed integer. + friend constexpr int128 Int128Max(); + + // Int128Min() + // + // Returns the minimum value for a 128-bit signed integer. + friend constexpr int128 Int128Min(); + + // Support for absl::Hash. + template <typename H> + friend H AbslHashValue(H h, int128 v) { + return H::combine(std::move(h), Int128High64(v), Int128Low64(v)); + } + + private: + constexpr int128(int64_t high, uint64_t low); + +#if defined(ABSL_HAVE_INTRINSIC_INT128) + __int128 v_; +#else // ABSL_HAVE_INTRINSIC_INT128 +#if defined(ABSL_IS_LITTLE_ENDIAN) + uint64_t lo_; + int64_t hi_; +#elif defined(ABSL_IS_BIG_ENDIAN) + int64_t hi_; + uint64_t lo_; +#else // byte order +#error "Unsupported byte order: must be little-endian or big-endian." +#endif // byte order +#endif // ABSL_HAVE_INTRINSIC_INT128 +}; + +std::ostream& operator<<(std::ostream& os, int128 v); + +// TODO(absl-team) add operator>>(std::istream&, int128) + +constexpr int128 Int128Max() { + return int128((std::numeric_limits<int64_t>::max)(), + (std::numeric_limits<uint64_t>::max)()); +} + +constexpr int128 Int128Min() { + return int128((std::numeric_limits<int64_t>::min)(), 0); +} + +} // namespace absl + +// Specialized numeric_limits for int128. +namespace std { +template <> +class numeric_limits<absl::int128> { + public: + static constexpr bool is_specialized = true; + static constexpr bool is_signed = true; + 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 = false; + static constexpr int digits = 127; + 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<__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::int128 (min)() { return absl::Int128Min(); } + static constexpr absl::int128 lowest() { return absl::Int128Min(); } + static constexpr absl::int128 (max)() { return absl::Int128Max(); } + static constexpr absl::int128 epsilon() { return 0; } + static constexpr absl::int128 round_error() { return 0; } + static constexpr absl::int128 infinity() { return 0; } + static constexpr absl::int128 quiet_NaN() { return 0; } + static constexpr absl::int128 signaling_NaN() { return 0; } + static constexpr absl::int128 denorm_min() { return 0; } +}; +} // namespace std // -------------------------------------------------------------------------- // Implementation details follow @@ -339,6 +571,10 @@ inline uint128& uint128::operator=(unsigned __int128 v) { } #endif // ABSL_HAVE_INTRINSIC_INT128 +inline uint128& uint128::operator=(int128 v) { + return *this = uint128(v); +} + // Arithmetic operators. uint128 operator<<(uint128 lhs, int amount); @@ -420,6 +656,9 @@ constexpr uint128::uint128(unsigned __int128 v) hi_{static_cast<uint64_t>(v >> 64)} {} #endif // ABSL_HAVE_INTRINSIC_INT128 +constexpr uint128::uint128(int128 v) + : lo_{Int128Low64(v)}, hi_{static_cast<uint64_t>(Int128High64(v))} {} + #elif defined(ABSL_IS_BIG_ENDIAN) constexpr uint128::uint128(uint64_t high, uint64_t low) @@ -450,6 +689,9 @@ constexpr uint128::uint128(unsigned __int128 v) lo_{static_cast<uint64_t>(v & ~uint64_t{0})} {} #endif // ABSL_HAVE_INTRINSIC_INT128 +constexpr uint128::uint128(int128 v) + : hi_{static_cast<uint64_t>(Int128High64(v))}, lo_{Int128Low64(v)} {} + #else // byte order #error "Unsupported byte order: must be little-endian or big-endian." #endif // byte order @@ -719,6 +961,117 @@ inline uint128& uint128::operator--() { return *this; } +constexpr int128 MakeInt128(int64_t high, uint64_t low) { + return int128(high, low); +} + +// Assignment from integer types. +inline int128& int128::operator=(int v) { + return *this = int128(v); +} + +inline int128& int128::operator=(unsigned int v) { + return *this = int128(v); +} + +inline int128& int128::operator=(long v) { // NOLINT(runtime/int) + return *this = int128(v); +} + +// NOLINTNEXTLINE(runtime/int) +inline int128& int128::operator=(unsigned long v) { + return *this = int128(v); +} + +// NOLINTNEXTLINE(runtime/int) +inline int128& int128::operator=(long long v) { + return *this = int128(v); +} + +// NOLINTNEXTLINE(runtime/int) +inline int128& int128::operator=(unsigned long long v) { + return *this = int128(v); +} + +// Arithmetic operators. + +int128 operator+(int128 lhs, int128 rhs); +int128 operator-(int128 lhs, int128 rhs); +int128 operator*(int128 lhs, int128 rhs); +int128 operator/(int128 lhs, int128 rhs); +int128 operator%(int128 lhs, int128 rhs); +int128 operator|(int128 lhs, int128 rhs); +int128 operator&(int128 lhs, int128 rhs); +int128 operator^(int128 lhs, int128 rhs); +int128 operator<<(int128 lhs, int amount); +int128 operator>>(int128 lhs, int amount); + +inline int128& int128::operator+=(int128 other) { + *this = *this + other; + return *this; +} + +inline int128& int128::operator-=(int128 other) { + *this = *this - other; + return *this; +} + +inline int128& int128::operator*=(int128 other) { + *this = *this * other; + return *this; +} + +inline int128& int128::operator/=(int128 other) { + *this = *this / other; + return *this; +} + +inline int128& int128::operator%=(int128 other) { + *this = *this % other; + return *this; +} + +inline int128& int128::operator|=(int128 other) { + *this = *this | other; + return *this; +} + +inline int128& int128::operator&=(int128 other) { + *this = *this & other; + return *this; +} + +inline int128& int128::operator^=(int128 other) { + *this = *this ^ other; + return *this; +} + +inline int128& int128::operator<<=(int amount) { + *this = *this << amount; + return *this; +} + +inline int128& int128::operator>>=(int amount) { + *this = *this >> amount; + return *this; +} + +namespace int128_internal { + +// Casts from unsigned to signed while preserving the underlying binary +// representation. +constexpr int64_t BitCastToSigned(uint64_t v) { + // Casting an unsigned integer to a signed integer of the same + // width is implementation defined behavior if the source value would not fit + // in the destination type. We step around it with a roundtrip bitwise not + // operation to make sure this function remains constexpr. Clang, GCC, and + // MSVC optimize this to a no-op on x86-64. + return v & (uint64_t{1} << 63) ? ~static_cast<int64_t>(~v) + : static_cast<int64_t>(v); +} + +} // namespace int128_internal + #if defined(ABSL_HAVE_INTRINSIC_INT128) #include "absl/numeric/int128_have_intrinsic.inc" // IWYU pragma: export #else // ABSL_HAVE_INTRINSIC_INT128 |