312 lines
11 KiB
C++
312 lines
11 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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// https://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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// This file contains :int128 implementation details that depend on internal
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// representation when ABSL_HAVE_INTRINSIC_INT128 is *not* defined. This file
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// is included by int128.h and relies on ABSL_INTERNAL_WCHAR_T being defined.
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constexpr uint64_t Int128Low64(int128 v) { return v.lo_; }
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constexpr int64_t Int128High64(int128 v) { return v.hi_; }
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#if defined(ABSL_IS_LITTLE_ENDIAN)
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constexpr int128::int128(int64_t high, uint64_t low) :
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lo_(low), hi_(high) {}
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constexpr int128::int128(int v)
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: lo_{static_cast<uint64_t>(v)}, hi_{v < 0 ? ~int64_t{0} : 0} {}
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constexpr int128::int128(long v) // NOLINT(runtime/int)
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: lo_{static_cast<uint64_t>(v)}, hi_{v < 0 ? ~int64_t{0} : 0} {}
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constexpr int128::int128(long long v) // NOLINT(runtime/int)
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: lo_{static_cast<uint64_t>(v)}, hi_{v < 0 ? ~int64_t{0} : 0} {}
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constexpr int128::int128(unsigned int v) : lo_{v}, hi_{0} {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr int128::int128(unsigned long v) : lo_{v}, hi_{0} {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr int128::int128(unsigned long long v) : lo_{v}, hi_{0} {}
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constexpr int128::int128(uint128 v)
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: lo_{Uint128Low64(v)}, hi_{static_cast<int64_t>(Uint128High64(v))} {}
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#elif defined(ABSL_IS_BIG_ENDIAN)
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constexpr int128::int128(int64_t high, uint64_t low) :
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hi_{high}, lo_{low} {}
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constexpr int128::int128(int v)
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: hi_{v < 0 ? ~int64_t{0} : 0}, lo_{static_cast<uint64_t>(v)} {}
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constexpr int128::int128(long v) // NOLINT(runtime/int)
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: hi_{v < 0 ? ~int64_t{0} : 0}, lo_{static_cast<uint64_t>(v)} {}
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constexpr int128::int128(long long v) // NOLINT(runtime/int)
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: hi_{v < 0 ? ~int64_t{0} : 0}, lo_{static_cast<uint64_t>(v)} {}
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constexpr int128::int128(unsigned int v) : hi_{0}, lo_{v} {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr int128::int128(unsigned long v) : hi_{0}, lo_{v} {}
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// NOLINTNEXTLINE(runtime/int)
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constexpr int128::int128(unsigned long long v) : hi_{0}, lo_{v} {}
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constexpr int128::int128(uint128 v)
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: hi_{static_cast<int64_t>(Uint128High64(v))}, lo_{Uint128Low64(v)} {}
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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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constexpr int128::operator bool() const { return lo_ || hi_; }
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constexpr int128::operator char() const {
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// NOLINTNEXTLINE(runtime/int)
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return static_cast<char>(static_cast<long long>(*this));
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}
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constexpr int128::operator signed char() const {
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// NOLINTNEXTLINE(runtime/int)
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return static_cast<signed char>(static_cast<long long>(*this));
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}
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constexpr int128::operator unsigned char() const {
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return static_cast<unsigned char>(lo_);
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}
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constexpr int128::operator char16_t() const {
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return static_cast<char16_t>(lo_);
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}
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constexpr int128::operator char32_t() const {
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return static_cast<char32_t>(lo_);
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}
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constexpr int128::operator ABSL_INTERNAL_WCHAR_T() const {
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// NOLINTNEXTLINE(runtime/int)
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return static_cast<ABSL_INTERNAL_WCHAR_T>(static_cast<long long>(*this));
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}
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constexpr int128::operator short() const { // NOLINT(runtime/int)
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// NOLINTNEXTLINE(runtime/int)
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return static_cast<short>(static_cast<long long>(*this));
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}
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constexpr int128::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 int128::operator int() const {
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// NOLINTNEXTLINE(runtime/int)
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return static_cast<int>(static_cast<long long>(*this));
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}
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constexpr int128::operator unsigned int() const {
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return static_cast<unsigned int>(lo_);
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}
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constexpr int128::operator long() const { // NOLINT(runtime/int)
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// NOLINTNEXTLINE(runtime/int)
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return static_cast<long>(static_cast<long long>(*this));
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}
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constexpr int128::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 int128::operator long long() const { // NOLINT(runtime/int)
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// We don't bother checking the value of hi_. If *this < 0, lo_'s high bit
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// must be set in order for the value to fit into a long long. Conversely, if
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// lo_'s high bit is set, *this must be < 0 for the value to fit.
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return int128_internal::BitCastToSigned(lo_);
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}
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constexpr int128::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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inline int128::operator float() const {
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// We must convert the absolute value and then negate as needed, because
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// floating point types are typically sign-magnitude. Otherwise, the
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// difference between the high and low 64 bits when interpreted as two's
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// complement overwhelms the precision of the mantissa.
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//
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// Also check to make sure we don't negate Int128Min()
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return hi_ < 0 && *this != Int128Min()
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? -static_cast<float>(-*this)
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: static_cast<float>(lo_) +
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std::ldexp(static_cast<float>(hi_), 64);
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}
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inline int128::operator double() const {
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// See comment in int128::operator float() above.
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return hi_ < 0 && *this != Int128Min()
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? -static_cast<double>(-*this)
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: static_cast<double>(lo_) +
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std::ldexp(static_cast<double>(hi_), 64);
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}
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inline int128::operator long double() const {
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// See comment in int128::operator float() above.
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return hi_ < 0 && *this != Int128Min()
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? -static_cast<long double>(-*this)
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: 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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constexpr bool operator==(int128 lhs, int128 rhs) {
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return (Int128Low64(lhs) == Int128Low64(rhs) &&
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Int128High64(lhs) == Int128High64(rhs));
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}
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constexpr bool operator!=(int128 lhs, int128 rhs) { return !(lhs == rhs); }
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constexpr bool operator<(int128 lhs, int128 rhs) {
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return (Int128High64(lhs) == Int128High64(rhs))
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? (Int128Low64(lhs) < Int128Low64(rhs))
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: (Int128High64(lhs) < Int128High64(rhs));
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}
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constexpr bool operator>(int128 lhs, int128 rhs) {
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return (Int128High64(lhs) == Int128High64(rhs))
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? (Int128Low64(lhs) > Int128Low64(rhs))
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: (Int128High64(lhs) > Int128High64(rhs));
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}
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constexpr bool operator<=(int128 lhs, int128 rhs) { return !(lhs > rhs); }
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constexpr bool operator>=(int128 lhs, int128 rhs) { return !(lhs < rhs); }
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// Unary operators.
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constexpr int128 operator-(int128 v) {
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return MakeInt128(~Int128High64(v) + (Int128Low64(v) == 0),
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~Int128Low64(v) + 1);
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}
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constexpr bool operator!(int128 v) {
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return !Int128Low64(v) && !Int128High64(v);
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}
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constexpr int128 operator~(int128 val) {
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return MakeInt128(~Int128High64(val), ~Int128Low64(val));
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}
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// Arithmetic operators.
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namespace int128_internal {
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constexpr int128 SignedAddResult(int128 result, int128 lhs) {
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// check for carry
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return (Int128Low64(result) < Int128Low64(lhs))
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? MakeInt128(Int128High64(result) + 1, Int128Low64(result))
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: result;
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}
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} // namespace int128_internal
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constexpr int128 operator+(int128 lhs, int128 rhs) {
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return int128_internal::SignedAddResult(
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MakeInt128(Int128High64(lhs) + Int128High64(rhs),
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Int128Low64(lhs) + Int128Low64(rhs)),
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lhs);
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}
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namespace int128_internal {
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constexpr int128 SignedSubstructResult(int128 result, int128 lhs, int128 rhs) {
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// check for carry
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return (Int128Low64(lhs) < Int128Low64(rhs))
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? MakeInt128(Int128High64(result) - 1, Int128Low64(result))
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: result;
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}
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} // namespace int128_internal
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constexpr int128 operator-(int128 lhs, int128 rhs) {
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return int128_internal::SignedSubstructResult(
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MakeInt128(Int128High64(lhs) - Int128High64(rhs),
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Int128Low64(lhs) - Int128Low64(rhs)),
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lhs, rhs);
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}
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inline int128 operator*(int128 lhs, int128 rhs) {
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return MakeInt128(
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int128_internal::BitCastToSigned(Uint128High64(uint128(lhs) * rhs)),
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Uint128Low64(uint128(lhs) * rhs));
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}
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inline int128 int128::operator++(int) {
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int128 tmp(*this);
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*this += 1;
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return tmp;
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}
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inline int128 int128::operator--(int) {
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int128 tmp(*this);
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*this -= 1;
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return tmp;
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}
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inline int128& int128::operator++() {
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*this += 1;
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return *this;
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}
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inline int128& int128::operator--() {
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*this -= 1;
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return *this;
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}
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constexpr int128 operator|(int128 lhs, int128 rhs) {
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return MakeInt128(Int128High64(lhs) | Int128High64(rhs),
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Int128Low64(lhs) | Int128Low64(rhs));
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}
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constexpr int128 operator&(int128 lhs, int128 rhs) {
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return MakeInt128(Int128High64(lhs) & Int128High64(rhs),
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Int128Low64(lhs) & Int128Low64(rhs));
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}
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constexpr int128 operator^(int128 lhs, int128 rhs) {
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return MakeInt128(Int128High64(lhs) ^ Int128High64(rhs),
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Int128Low64(lhs) ^ Int128Low64(rhs));
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}
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constexpr int128 operator<<(int128 lhs, int amount) {
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// int64_t shifts of >= 64 are undefined, so we need some special-casing.
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return amount >= 64
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? MakeInt128(
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static_cast<int64_t>(Int128Low64(lhs) << (amount - 64)), 0)
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: amount == 0
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? lhs
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: MakeInt128(
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(Int128High64(lhs) << amount) |
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static_cast<int64_t>(Int128Low64(lhs) >> (64 - amount)),
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Int128Low64(lhs) << amount);
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}
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constexpr int128 operator>>(int128 lhs, int amount) {
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// int64_t shifts of >= 64 are undefined, so we need some special-casing.
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// The (Int128High64(lhs) >> 32) >> 32 "trick" causes the the most significant
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// int64 to be inititialized with all zeros or all ones correctly. It takes
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// into account whether the number is negative or positive, and whether the
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// current architecture does arithmetic or logical right shifts for negative
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// numbers.
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return amount >= 64
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? MakeInt128(
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(Int128High64(lhs) >> 32) >> 32,
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static_cast<uint64_t>(Int128High64(lhs) >> (amount - 64)))
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: amount == 0
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? lhs
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: MakeInt128(Int128High64(lhs) >> amount,
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(Int128Low64(lhs) >> amount) |
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(static_cast<uint64_t>(Int128High64(lhs))
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<< (64 - amount)));
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}
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