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tdfec/td/fec/online/Decoder.cpp

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+/*
+    This file is part of TON Blockchain Library.
+
+    TON Blockchain Library is free software: you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation, either version 2 of the License, or
+    (at your option) any later version.
+
+    TON Blockchain Library is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with TON Blockchain Library.  If not, see <http://www.gnu.org/licenses/>.
+
+    Copyright 2017-2019 Telegram Systems LLP
+*/
+#include "td/fec/online/Decoder.h"
+
+namespace td {
+namespace online_code {
+Result<std::unique_ptr<Decoder>> Decoder::create(Encoder::Parameters p) {
+  return std::make_unique<Decoder>(p.symbol_size, p.data_size);
+}
+
+Decoder::Decoder(size_t symbol_size, size_t data_size)
+    : parameters_(Rfc::get_parameters((data_size + symbol_size - 1) / symbol_size).move_as_ok())
+    , symbol_size_(symbol_size)
+    , data_size_(data_size) {
+  MatrixGF256 d_{1, symbol_size_};
+  d_.set_zero();
+  std::vector<uint32> e_cnt(parameters_.outer_encoding_blocks_count(), 0);
+  std::vector<std::vector<uint32>> e(parameters_.outer_encoding_blocks_count());
+  parameters_.outer_encoding_for_each([&](uint32 i, uint32 j) { e_cnt[i]++; });
+  for (uint32 i = 0; i < parameters_.outer_encoding_blocks_count(); i++) {
+    e[i].reserve(e_cnt[i]);
+  }
+  parameters_.outer_encoding_for_each([&](uint32 i, uint32 j) { e[i].push_back(j); });
+  for (uint32 i = 0; i < parameters_.outer_encoding_blocks_count(); i++) {
+    decoding_.add_equation(e[i], d_.row(0));
+  }
+}
+
+Status Decoder::add_symbol(raptorq::SymbolRef symbol_ref) {
+  if (symbol_ref.data.size() != symbol_size_) {
+    return Status::Error("Symbol has invalid length");
+  }
+
+  auto offset = decoding_.ready_symbols().size();
+  decoding_.add_equation(parameters_.get_inner_encoding_row(symbol_ref.id), symbol_ref.data);
+
+  //LOG(ERROR) << inner_decoding_.ready_symbols().size();
+  for (auto symbol_id : decoding_.ready_symbols().substr(offset)) {
+    if (symbol_id < parameters_.source_blocks_count()) {
+      ready_cnt_++;
+    }
+  }
+  return Status::OK();
+}
+
+bool Decoder::is_ready() const {
+  return ready_cnt_ == parameters_.source_blocks_count();
+}
+
+BufferSlice Decoder::get_data() const {
+  CHECK(is_ready());
+  BufferSlice res(data_size_);
+  for (uint32 i = 0; i < parameters_.source_blocks_count(); i++) {
+    auto dest = res.as_slice().substr(i * symbol_size_);
+    dest.copy_from(decoding_.get_symbol(i).truncate(dest.size()));
+  }
+  return res;
+}
+
+}  // namespace online_code
+}  // namespace td