[onert] Introduce CheckpointLoader to load checkpoint file

This commit introduces CheckpointLoader class. It loads the checkpoint
file data and updates the tensor data and training information.

ONE-DCO-1.0-Signed-off-by: Jiyoung Yun <[email protected]>

runtime/onert/api/nnfw/src/nnfw_api_internal.cc

@@ -25,6 +25,7 @@
 #include "loader/ModelLoader.h"
 #include "loader/TFLiteLoader.h"
 #include "loader/TrainInfoLoader.h"
+#include "loader/train/CheckpointLoader.h"
 #include "exporter/CircleExporter.h"
 #include "exporter/train/CheckpointExporter.h"
 #include "json/json.h"
@@ -1718,7 +1719,7 @@ NNFW_STATUS nnfw_session::train_import_checkpoint(const char *path)
 
   try
   {
-    // TODO Implement importing checkpoint
+    onert::loader::train::loadCheckpoint(path, _train_info, _execution);
   }
   catch (const std::exception &e)
   {

runtime/onert/core/include/loader/train/CheckpointLoader.h

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2024 Samsung Electronics Co., Ltd. All Rights Reserved
+ *
+ * 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 __ONERT_LOADER_TRAIN_CHECKPOINT_LOADER_H__
+#define __ONERT_LOADER_TRAIN_CHECKPOINT_LOADER_H__
+
+#include <string>
+#include <memory>
+
+namespace onert
+{
+namespace exec
+{
+class Execution;
+} // namespace exec
+namespace ir
+{
+namespace train
+{
+class TrainingInfo;
+} // namespace train
+} // namespace ir
+} // namespace onert
+
+namespace onert
+{
+namespace loader
+{
+namespace train
+{
+
+void loadCheckpoint(const std::string &filename,
+                    const std::unique_ptr<ir::train::TrainingInfo> &train_info,
+                    const std::unique_ptr<exec::Execution> &exec);
+
+} // namespace train
+} // namespace loader
+} // namespace onert
+
+#endif // __ONERT_LOADER_TRAIN_CHECKPOINT_LOADER_H__

runtime/onert/core/src/loader/train/CheckpointLoader.cc

@@ -0,0 +1,108 @@
+/*
+ * Copyright (c) 2024 Samsung Electronics Co., Ltd. All Rights Reserved
+ *
+ * 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 "loader/train/CheckpointLoader.h"
+
+#include "exec/Execution.h"
+#include "ir/train/Checkpoint.h"
+#include "ir/train/TrainingInfo.h"
+
+#include <fstream>
+#include <filesystem>
+
+namespace
+{
+
+using namespace onert;
+using namespace ir;
+using namespace train;
+using namespace checkpoint;
+using namespace exec;
+
+class CheckpointLoader final
+{
+public:
+  CheckpointLoader(const std::string &filename)
+  {
+    if (filename.empty() || !std::filesystem::exists(filename))
+      throw std::runtime_error{"Invalid checkpoint file"};
+
+    _file.open(filename.c_str(), std::ios::binary | std::ios::in);
+    if (!_file.good())
+      throw std::runtime_error{"Failed to open checkpoint file"};
+
+    _file.seekg(0, std::ios::end);
+    const unsigned long filesize = _file.tellg();
+    _file.seekg(0, std::ios::beg);
+
+    if (filesize < sizeof(_header))
+      throw std::runtime_error{"Invalid checkpoint file data"};
+
+    memset(reinterpret_cast<char *>(&_header), 0, sizeof(_header));
+    _file.read(reinterpret_cast<char *>(&_header), sizeof(_header));
+    if (_file.fail())
+      throw std::runtime_error{"Failed to load header data"};
+
+    if (_header.magic != checkpoint::MAGIC_NUMBER)
+      throw std::runtime_error{"Invalid MAGIC NUMBER"};
+
+    if (_header.schema != checkpoint::SCHEMA_VERSION)
+      throw std::runtime_error{"Invalid SCHEMA VERSION"};
+
+    if (filesize - _header.other_offset != sizeof(_footer))
+      throw std::runtime_error{"Invalid checkpoint file footer data"};
+
+    memset(reinterpret_cast<char *>(&_footer), 0, sizeof(_footer));
+    _file.seekg(_header.other_offset, std::ios::beg);
+    _file.read(reinterpret_cast<char *>(&_footer), sizeof(_footer));
+  }
+
+  ~CheckpointLoader()
+  {
+    if (_file.is_open())
+      _file.close();
+  }
+
+private:
+  std::ifstream _file;
+  checkpoint::Header _header;
+  checkpoint::Footer _footer;
+};
+
+} // namespace
+
+namespace onert
+{
+namespace loader
+{
+namespace train
+{
+
+void loadCheckpoint(const std::string &filename,
+                    const std::unique_ptr<ir::train::TrainingInfo> &train_info,
+                    const std::unique_ptr<onert::exec::Execution> &exec)
+{
+  CheckpointLoader loader(filename);
+
+  // TODO Load tensor data
+  UNUSED_RELEASE(exec);
+  // TODO Update step in train_info
+  UNUSED_RELEASE(train_info);
+}
+
+} // namespace train
+} // namespace loader
+} // namespace onert