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104 lines
3.0 KiB
C++
104 lines
3.0 KiB
C++
/*
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This file is part of TON Blockchain Library.
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TON Blockchain Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 2 of the License, or
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(at your option) any later version.
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TON Blockchain Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with TON Blockchain Library. If not, see <http://www.gnu.org/licenses/>.
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Copyright 2017-2019 Telegram Systems LLP
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*/
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#pragma once
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#include <random>
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#include <algorithm>
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#include "td/utils/Status.h"
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#include "td/utils/Span.h"
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#include "td/utils/Random.h"
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namespace td {
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namespace online_code {
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template <class Random>
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class UniformDistributionSimple {
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public:
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UniformDistributionSimple(uint32 L, uint32 R) : L_(L), R_(R) {
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}
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void set_random(Random *random) {
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random_ = random;
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}
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uint32 operator()() {
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return static_cast<uint32>((*random_)() % (R_ - L_ + 1)) + L_;
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}
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private:
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Random *random_{nullptr};
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uint32 L_;
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uint32 R_;
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};
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using Random = Random::Xorshift128plus;
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using UniformDistribution = UniformDistributionSimple<Random>;
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class Rfc {
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public:
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class Parameters {
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public:
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Parameters(size_t source_blocks, double epsilon, uint32 quality);
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size_t source_blocks_count() const;
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size_t outer_encoding_blocks_count() const;
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size_t estimated_packets() const;
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template <class F>
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void outer_encoding_for_each(F &&f) const {
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Random r(static_cast<uint32>(1));
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outer_distribution_.set_random(&r);
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for (uint32 j = 0; j < outer_encoding_blocks_count(); j++) {
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f(j, uint32(source_blocks_count() + j));
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}
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for (uint32 i = 0; i < source_blocks_count(); i++) {
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for (uint32 j = 0; j < quality_; j++) {
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f(outer_distribution_(), i);
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}
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}
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}
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Span<uint32> get_inner_encoding_row(size_t row_id) const;
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private:
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struct DegreeDistribution {
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public:
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DegreeDistribution(double epsilon);
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uint32 get_degree(double x) const;
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size_t get_max_degree() const;
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private:
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std::vector<double> p_;
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};
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uint32 source_blocks_;
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double epsilon_;
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uint32 quality_;
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DegreeDistribution degree_distribution_;
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size_t outer_encoding_blocks_count_;
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mutable std::vector<uint32> row_buffer_ = std::vector<uint32>(degree_distribution_.get_max_degree(), 0);
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mutable UniformDistribution outer_distribution_{0, static_cast<uint32>(outer_encoding_blocks_count()) - 1};
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mutable UniformDistribution inner_distribution_{
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0, static_cast<uint32>(outer_encoding_blocks_count() + source_blocks_count()) - 1};
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};
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static Result<Parameters> get_parameters(size_t K);
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};
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} // namespace online_code
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} // namespace td
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