280 lines
6.5 KiB
C++
280 lines
6.5 KiB
C++
//
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// Copyright Aliaksei Levin (levlam@telegram.org), Arseny Smirnov (arseny30@gmail.com) 2014-2020
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#pragma once
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#include "td/utils/bits.h"
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#include "td/utils/common.h"
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#include <limits>
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#include <type_traits>
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namespace td {
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class uint128_emulated {
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public:
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using uint128 = uint128_emulated;
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uint128_emulated(uint64 hi, uint64 lo) : hi_(hi), lo_(lo) {
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}
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template <class T, typename = std::enable_if_t<std::is_unsigned<T>::value>>
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uint128_emulated(T lo) : uint128_emulated(0, lo) {
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}
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uint128_emulated() = default;
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uint64 hi() const {
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return hi_;
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}
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uint64 lo() const {
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return lo_;
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}
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static uint128 from_signed(int64 x) {
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if (x >= 0) {
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return uint128(0, x);
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}
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return uint128(std::numeric_limits<uint64>::max(), static_cast<uint64>(x));
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}
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uint128 add(uint128 other) const {
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uint128 res(other.hi() + hi(), other.lo() + lo());
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if (res.lo() < lo()) {
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res.hi_++;
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}
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return res;
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}
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uint128 shl(int cnt) const {
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if (cnt == 0) {
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return *this;
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}
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if (cnt < 64) {
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return uint128((hi() << cnt) | (lo() >> (64 - cnt)), lo() << cnt);
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}
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if (cnt < 128) {
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return uint128(lo() << (cnt - 64), 0);
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}
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return uint128();
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}
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uint128 shr(int cnt) const {
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if (cnt == 0) {
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return *this;
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}
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if (cnt < 64) {
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return uint128(hi() >> cnt, (lo() >> cnt) | (hi() << (64 - cnt)));
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}
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if (cnt < 128) {
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return uint128(0, hi() >> (cnt - 64));
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}
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return uint128();
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}
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uint128 mult(uint128 other) const {
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uint64 a_lo = lo() & 0xffffffff;
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uint64 a_hi = lo() >> 32;
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uint64 b_lo = other.lo() & 0xffffffff;
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uint64 b_hi = other.lo() >> 32;
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uint128 res(lo() * other.hi() + hi() * other.lo() + a_hi * b_hi, a_lo * b_lo);
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uint128 add1(0, a_lo * b_hi);
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uint128 add2(0, a_hi * b_lo);
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return res.add(add1.shl(32)).add(add2.shl(32));
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}
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uint128 mult(uint64 other) const {
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return mult(uint128(0, other));
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}
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uint128 mult_signed(int64 other) const {
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return mult(uint128::from_signed(other));
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}
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bool is_zero() const {
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return lo() == 0 && hi() == 0;
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}
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uint128 sub(uint128 other) const {
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uint32 carry = 0;
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if (other.lo() > lo()) {
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carry = 1;
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}
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return uint128(hi() - other.hi() - carry, lo() - other.lo());
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}
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void divmod(uint128 other, uint128 *div_res, uint128 *mod_res) const {
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CHECK(!other.is_zero());
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auto from = *this;
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auto ctz = from.count_leading_zeroes();
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auto other_ctz = other.count_leading_zeroes();
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if (ctz > other_ctz) {
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*div_res = uint128();
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*mod_res = from;
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return;
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}
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auto shift = other_ctz - ctz;
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auto res = uint128();
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for (int i = shift; i >= 0; i--) {
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auto sub = other.shl(i);
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res = res.shl(1);
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if (from.greater_or_equal(sub)) {
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from = from.sub(sub);
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res = res.set_lower_bit();
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}
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}
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*div_res = res;
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*mod_res = from;
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}
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uint128 div(uint128 other) const {
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uint128 a, b;
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divmod(other, &a, &b);
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return a;
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}
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uint128 mod(uint128 other) const {
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uint128 a, b;
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divmod(other, &a, &b);
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return b;
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}
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void divmod_signed(int64 y, int64 *quot, int64 *rem) const {
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CHECK(y != 0);
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auto x = *this;
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int x_sgn = x.is_negative();
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int y_sgn = y < 0;
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if (x_sgn) {
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x = x.negate();
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}
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uint128 uy = from_signed(y);
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if (uy.is_negative()) {
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uy = uy.negate();
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}
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uint128 t_quot, t_mod;
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x.divmod(uy, &t_quot, &t_mod);
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*quot = t_quot.lo();
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*rem = t_mod.lo();
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if (x_sgn != y_sgn) {
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*quot = -*quot;
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}
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if (x_sgn) {
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*rem = -*rem;
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}
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}
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private:
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uint64 hi_{0};
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uint64 lo_{0};
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bool is_negative() const {
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return (hi_ >> 63) == 1;
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}
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int32 count_leading_zeroes() const {
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if (hi() == 0) {
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return 64 + count_leading_zeroes64(lo());
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}
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return count_leading_zeroes64(hi());
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}
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uint128 set_lower_bit() const {
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return uint128(hi(), lo() | 1);
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}
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bool greater_or_equal(uint128 other) const {
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return hi() > other.hi() || (hi() == other.hi() && lo() >= other.lo());
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}
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uint128 negate() const {
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uint128 res(~hi(), ~lo() + 1);
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if (res.lo() == 0) {
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return uint128(res.hi() + 1, 0);
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}
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return res;
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}
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};
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#if TD_HAVE_INT128
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class uint128_intrinsic {
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public:
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using ValueT = unsigned __int128;
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using uint128 = uint128_intrinsic;
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explicit uint128_intrinsic(ValueT value) : value_(value) {
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}
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uint128_intrinsic(uint64 hi, uint64 lo) : value_((ValueT(hi) << 64) | lo) {
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}
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uint128_intrinsic() = default;
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static uint128 from_signed(int64 x) {
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return uint128(static_cast<ValueT>(x));
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}
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uint64 hi() const {
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return uint64(value() >> 64);
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}
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uint64 lo() const {
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return uint64(value() & std::numeric_limits<uint64>::max());
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}
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uint128 add(uint128 other) const {
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return uint128(value() + other.value());
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}
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uint128 sub(uint128 other) const {
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return uint128(value() - other.value());
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}
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uint128 shl(int cnt) const {
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if (cnt >= 128) {
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return uint128();
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}
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return uint128(value() << cnt);
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}
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uint128 shr(int cnt) const {
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if (cnt >= 128) {
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return uint128();
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}
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return uint128(value() >> cnt);
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}
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uint128 mult(uint128 other) const {
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return uint128(value() * other.value());
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}
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uint128 mult(uint64 other) const {
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return uint128(value() * other);
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}
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uint128 mult_signed(int64 other) const {
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return uint128(value() * other);
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}
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bool is_zero() const {
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return value() == 0;
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}
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void divmod(uint128 other, uint128 *div_res, uint128 *mod_res) const {
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CHECK(!other.is_zero());
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*div_res = uint128(value() / other.value());
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*mod_res = uint128(value() % other.value());
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}
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uint128 div(uint128 other) const {
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CHECK(!other.is_zero());
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return uint128(value() / other.value());
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}
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uint128 mod(uint128 other) const {
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CHECK(!other.is_zero());
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return uint128(value() % other.value());
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}
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void divmod_signed(int64 y, int64 *quot, int64 *rem) const {
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CHECK(y != 0);
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*quot = (int64)(signed_value() / y);
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*rem = (int64)(signed_value() % y);
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}
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private:
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unsigned __int128 value_{0};
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ValueT value() const {
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return value_;
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}
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__int128 signed_value() const {
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return static_cast<__int128>(value());
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}
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};
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#endif
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#if TD_HAVE_INT128
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using uint128 = uint128_intrinsic;
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#else
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using uint128 = uint128_emulated;
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#endif
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} // namespace td
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