From 3c1c4f361ae38205c70fbc5de7f3292f79f04e3a Mon Sep 17 00:00:00 2001
From: Hans Gaiser <j.c.gaiser@delftrobotics.com>
Date: Mon, 13 Feb 2017 17:49:24 +0100
Subject: [PATCH] Add example layer module.

---
 examples/modular_layer/CMakeLists.txt        |  22 ++++
 examples/modular_layer/src/modular_layer.cpp | 108 +++++++++++++++++++
 2 files changed, 130 insertions(+)
 create mode 100644 examples/modular_layer/CMakeLists.txt
 create mode 100644 examples/modular_layer/src/modular_layer.cpp

diff --git a/examples/modular_layer/CMakeLists.txt b/examples/modular_layer/CMakeLists.txt
new file mode 100644
index 00000000000..d47779ef26c
--- /dev/null
+++ b/examples/modular_layer/CMakeLists.txt
@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.1)
+project(CaffeModularLayer)
+
+find_package(Caffe REQUIRED)
+find_package(CUDA REQUIRED)
+
+include_directories(${Caffe_INCLUDE_DIRS} ${CUDA_INCLUDE_DIRS})
+
+# This example acts as a standalone example, but Caffe insists on building
+# the cpp file. We define COMPILE_MODULAR_LAYER to let the cpp file know
+# it is being build from this CMakeLists.txt.
+add_definitions(-DCOMPILE_MODULAR_LAYER)
+
+# These variables are used as prefix and suffix for the generated module.
+# They can be overwritten as below, but make sure they match with what
+# is expected on the Caffe side (either through cmake or Makefile.config).
+#set(CMAKE_SHARED_MODULE_PREFIX "lib")
+#set(CMAKE_SHARED_MODULE_SUFFIX ".so")
+
+# Use MODULE here to generate a module which we can load during runtime.
+add_library(modular_layer MODULE src/modular_layer.cpp)
+target_link_libraries(modular_layer ${Caffe_LIBRARIES} ${CUDA_LIBRARIES})
diff --git a/examples/modular_layer/src/modular_layer.cpp b/examples/modular_layer/src/modular_layer.cpp
new file mode 100644
index 00000000000..39f6e948e5f
--- /dev/null
+++ b/examples/modular_layer/src/modular_layer.cpp
@@ -0,0 +1,108 @@
+#if defined(COMPILE_MODULAR_LAYER)
+
+#include <caffe/caffe.hpp>
+
+#include <vector>
+
+/*
+ * Example of how to use this layer in prototxt files
+ * layer {
+ *   name: "layer_module"
+ *   type: "Module"
+ *   bottom: "some_bottom"
+ *   top: "some_top"
+ *   module_param {
+ *     library: "modular_layer"
+ *     type: "ExampleModular"
+ *     param_str: "5"
+ *     #creator_symbol: "CreateExampleModularLayer" # Only when overriding
+ *     #deleter_symbol: "DeleteExampleModularlayer" # Only when overriding
+ *   }
+ * }
+*/
+
+namespace caffe {
+
+template <typename Dtype>
+class ExampleModularLayer: public Layer<Dtype> {
+ public:
+  explicit ExampleModularLayer(const LayerParameter& param)
+    : Layer<Dtype>(param) {}
+
+  void LayerSetUp(const std::vector<Blob<Dtype>*>&,
+    const std::vector<Blob<Dtype>*>&) {
+    // parse params from param_str
+    // this param is a string type, but can represent
+    // int, float, json, yaml... whatever the module implementation requires
+    // (in this case it is parsed as an int)
+    some_param = std::stoi(this->layer_param_.module_param().param_str());
+  }
+
+  virtual inline const char* type() const { return "ExampleModular"; }
+
+ protected:
+  virtual void Reshape(const vector<Blob<Dtype>*>&,
+      const vector<Blob<Dtype>*>&) {}
+
+  virtual void Forward_cpu(const vector<Blob<Dtype>*>&,
+      const vector<Blob<Dtype>*>& top) {
+    top[0]->Reshape(1, 1, 1, some_param);
+  }
+
+  virtual void Backward_cpu(const vector<Blob<Dtype>*>&,
+      const vector<bool>&,
+      const vector<Blob<Dtype>*>&) {}
+
+  int some_param;
+};
+
+EXPORT_LAYER_MODULE_CLASS(ExampleModular);
+
+// the above macro can be expanded to the code below
+
+/*
+template <typename Dtype>
+Layer<Dtype> * CreateExampleModularLayer(const LayerParameter& param) {
+  return new ExampleModularLayer<Dtype>(param);
+}
+EXPORT_LAYER_MODULE_CREATOR(ExampleModular, CreateExampleModularLayer);
+*/
+
+// for which the last macro can be expanded as follows:
+
+/*
+extern "C" Layer<float> * CreateExampleModularLayer_float(
+  const LayerParameter& param
+) {
+  return new ExampleModularLayer<float>(param);
+}
+
+extern "C" Layer<double> * CreateExampleModularLayer_double(
+  const LayerParameter& param
+) {
+  return new ExampleModularLayer<double>(param);
+}
+*/
+
+// This function is not necessary, by default Caffe
+// will already call 'delete layer;', but this can be
+// used to override deletion behaviour.
+/*
+template <typename Dtype>
+void DeleteExampleModularLayer(Layer<Dtype> * layer) {
+  delete layer;
+}
+EXPORT_LAYER_MODULE_DELETER(DeleteExampleModularLayer);
+*/
+
+}  // namespace caffe
+
+#else
+
+// Caffe insists on building this file in their build system
+// so we give it a main to build
+int main() {
+  return 0;
+}
+
+#endif