Add CTC HLG decoding using OpenFst (#349)

sherpa-onnx/csrc/offline-zipformer-ctc-model-config.h

@@ -0,0 +1,32 @@
+// sherpa-onnx/csrc/offline-zipformer-ctc-model-config.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_OFFLINE_ZIPFORMER_CTC_MODEL_CONFIG_H_
+#define SHERPA_ONNX_CSRC_OFFLINE_ZIPFORMER_CTC_MODEL_CONFIG_H_
+
+#include <string>
+
+#include "sherpa-onnx/csrc/parse-options.h"
+
+namespace sherpa_onnx {
+
+// for
+// https://github.com/k2-fsa/icefall/blob/master/egs/librispeech/ASR/zipformer/export-onnx-ctc.py
+struct OfflineZipformerCtcModelConfig {
+  std::string model;
+
+  OfflineZipformerCtcModelConfig() = default;
+
+  explicit OfflineZipformerCtcModelConfig(const std::string &model)
+      : model(model) {}
+
+  void Register(ParseOptions *po);
+
+  bool Validate() const;
+
+  std::string ToString() const;
+};
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_OFFLINE_ZIPFORMER_CTC_MODEL_CONFIG_H_