Coverage Report

Created: 2025-06-13 07:02

/src/tesseract/src/lstm/parallel.h
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///////////////////////////////////////////////////////////////////////
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// File:        parallel.h
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// Description: Runs networks in parallel on the same input.
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// Author:      Ray Smith
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//
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// (C) Copyright 2013, Google Inc.
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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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// http://www.apache.org/licenses/LICENSE-2.0
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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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///////////////////////////////////////////////////////////////////////
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#ifndef TESSERACT_LSTM_PARALLEL_H_
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#define TESSERACT_LSTM_PARALLEL_H_
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#include "plumbing.h"
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namespace tesseract {
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// Runs multiple networks in parallel, interlacing their outputs.
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class Parallel : public Plumbing {
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public:
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  // ni_ and no_ will be set by AddToStack.
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  TESS_API
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  Parallel(const std::string &name, NetworkType type);
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  // Returns the shape output from the network given an input shape (which may
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  // be partially unknown ie zero).
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  StaticShape OutputShape(const StaticShape &input_shape) const override;
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  std::string spec() const override {
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    std::string spec;
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    if (type_ == NT_PAR_2D_LSTM) {
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      // We have 4 LSTMs operating in parallel here, so the size of each is
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      // the number of outputs/4.
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      spec += "L2xy" + std::to_string(no_ / 4);
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    } else if (type_ == NT_PAR_RL_LSTM) {
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      // We have 2 LSTMs operating in parallel here, so the size of each is
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      // the number of outputs/2.
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      if (stack_[0]->type() == NT_LSTM_SUMMARY) {
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        spec += "Lbxs" + std::to_string(no_ / 2);
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      } else {
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        spec += "Lbx" + std::to_string(no_ / 2);
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      }
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    } else {
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      if (type_ == NT_REPLICATED) {
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        spec += "R" + std::to_string(stack_.size()) + "(" + stack_[0]->spec();
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      } else {
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        for (auto &it : stack_) {
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          spec += it->spec();
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        }
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      }
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      spec += ")";
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    }
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    return spec;
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  }
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  // Runs forward propagation of activations on the input line.
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  // See Network for a detailed discussion of the arguments.
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  void Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose,
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               NetworkScratch *scratch, NetworkIO *output) override;
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  // Runs backward propagation of errors on the deltas line.
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  // See Network for a detailed discussion of the arguments.
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  bool Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,
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                NetworkIO *back_deltas) override;
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private:
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  // If *this is a NT_REPLICATED, then it feeds a replicated network with
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  // identical inputs, and it would be extremely wasteful for them to each
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  // calculate and store the same transpose of the inputs, so Parallel does it
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  // and passes a pointer to the replicated network, allowing it to use the
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  // transpose on the next call to Backward.
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  TransposedArray transposed_input_;
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};
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} // namespace tesseract.
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#endif // TESSERACT_LSTM_PARALLEL_H_