--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/tesseract/src/lstm/maxpool.cpp	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,77 @@
+///////////////////////////////////////////////////////////////////////
+// File:        maxpool.cpp
+// Description: Standard Max-Pooling layer.
+// Author:      Ray Smith
+//
+// (C) Copyright 2014, 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.
+///////////////////////////////////////////////////////////////////////
+
+#include "maxpool.h"
+
+namespace tesseract {
+
+Maxpool::Maxpool(const std::string &name, int ni, int x_scale, int y_scale)
+    : Reconfig(name, ni, x_scale, y_scale) {
+  type_ = NT_MAXPOOL;
+  no_ = ni;
+}
+
+// Reads from the given file. Returns false in case of error.
+bool Maxpool::DeSerialize(TFile *fp) {
+  bool result = Reconfig::DeSerialize(fp);
+  no_ = ni_;
+  return result;
+}
+
+// Runs forward propagation of activations on the input line.
+// See NetworkCpp for a detailed discussion of the arguments.
+void Maxpool::Forward(bool debug, const NetworkIO &input, const TransposedArray *input_transpose,
+                      NetworkScratch *scratch, NetworkIO *output) {
+  output->ResizeScaled(input, x_scale_, y_scale_, no_);
+  maxes_.ResizeNoInit(output->Width(), ni_);
+  back_map_ = input.stride_map();
+
+  StrideMap::Index dest_index(output->stride_map());
+  do {
+    int out_t = dest_index.t();
+    StrideMap::Index src_index(input.stride_map(), dest_index.index(FD_BATCH),
+                               dest_index.index(FD_HEIGHT) * y_scale_,
+                               dest_index.index(FD_WIDTH) * x_scale_);
+    // Find the max input out of x_scale_ groups of y_scale_ inputs.
+    // Do it independently for each input dimension.
+    int *max_line = maxes_[out_t];
+    int in_t = src_index.t();
+    output->CopyTimeStepFrom(out_t, input, in_t);
+    for (int i = 0; i < ni_; ++i) {
+      max_line[i] = in_t;
+    }
+    for (int x = 0; x < x_scale_; ++x) {
+      for (int y = 0; y < y_scale_; ++y) {
+        StrideMap::Index src_xy(src_index);
+        if (src_xy.AddOffset(x, FD_WIDTH) && src_xy.AddOffset(y, FD_HEIGHT)) {
+          output->MaxpoolTimeStep(out_t, input, src_xy.t(), max_line);
+        }
+      }
+    }
+  } while (dest_index.Increment());
+}
+
+// Runs backward propagation of errors on the deltas line.
+// See NetworkCpp for a detailed discussion of the arguments.
+bool Maxpool::Backward(bool debug, const NetworkIO &fwd_deltas, NetworkScratch *scratch,
+                       NetworkIO *back_deltas) {
+  back_deltas->ResizeToMap(fwd_deltas.int_mode(), back_map_, ni_);
+  back_deltas->MaxpoolBackward(fwd_deltas, maxes_);
+  return true;
+}
+
+} // namespace tesseract.