--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/lstm/reversed.h	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,90 @@
+///////////////////////////////////////////////////////////////////////
+// File:        reversed.h
+// Description: Runs a single network on time-reversed input, reversing output.
+// Author:      Ray Smith
+//
+// (C) Copyright 2013, Google Inc.
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+///////////////////////////////////////////////////////////////////////
+
+#ifndef TESSERACT_LSTM_REVERSED_H_
+#define TESSERACT_LSTM_REVERSED_H_
+
+#include "matrix.h"
+#include "plumbing.h"
+
+namespace tesseract {
+
+// C++ Implementation of the Reversed class from lstm.py.
+class Reversed : public Plumbing {
+public:
+  TESS_API
+  explicit Reversed(const std::string &name, NetworkType type);
+  ~Reversed() override = default;
+
+  // Returns the shape output from the network given an input shape (which may
+  // be partially unknown ie zero).
+  StaticShape OutputShape(const StaticShape &input_shape) const override;
+
+  std::string spec() const override {
+    std::string spec(type_ == NT_XREVERSED ? "Rx" : (type_ == NT_YREVERSED ? "Ry" : "Txy"));
+    // For most simple cases, we will output Rx<net> or Ry<net> where <net> is
+    // the network in stack_[0], but in the special case that <net> is an
+    // LSTM, we will just output the LSTM's spec modified to take the reversal
+    // into account. This is because when the user specified Lfy64, we actually
+    // generated TxyLfx64, and if the user specified Lrx64 we actually
+    // generated RxLfx64, and we want to display what the user asked for.
+    std::string net_spec(stack_[0]->spec());
+    if (net_spec[0] == 'L') {
+      // Setup a from and to character according to the type of the reversal
+      // such that the LSTM spec gets modified to the spec that the user
+      // asked for
+      char from = 'f';
+      char to = 'r';
+      if (type_ == NT_XYTRANSPOSE) {
+        from = 'x';
+        to = 'y';
+      }
+      // Change the from char to the to char.
+      for (auto &it : net_spec) {
+        if (it == from) {
+          it = to;
+        }
+      }
+      spec += net_spec;
+      return spec;
+    }
+    spec += net_spec;
+    return spec;
+  }
+
+  // Takes ownership of the given network to make it the reversed one.
+  TESS_API
+  void SetNetwork(Network *network);
+
+  // Runs forward propagation of activations on the input line.
+  // See Network for a detailed discussion of the arguments.
+  void Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose,
+               NetworkScratch *scratch, NetworkIO *output) override;
+
+  // Runs backward propagation of errors on the deltas line.
+  // See Network for a detailed discussion of the arguments.
+  bool Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,
+                NetworkIO *back_deltas) override;
+
+private:
+  // Copies src to *dest with the reversal according to type_.
+  void ReverseData(const NetworkIO &src, NetworkIO *dest) const;
+};
+
+} // namespace tesseract.
+
+#endif // TESSERACT_LSTM_REVERSED_H_