Add online LSTM transducer model (#25)

sherpa-onnx/csrc/onnx-utils.h

@@ -0,0 +1,60 @@
+// sherpa/csrc/onnx-utils.h
+//
+// Copyright (c)  2023  Xiaomi Corporation
+#ifndef SHERPA_ONNX_CSRC_ONNX_UTILS_H_
+#define SHERPA_ONNX_CSRC_ONNX_UTILS_H_
+
+#ifdef _MSC_VER
+// For ToWide() below
+#include <codecvt>
+#include <locale>
+#endif
+
+#include <ostream>
+#include <string>
+#include <vector>
+
+#include "onnxruntime_cxx_api.h"  // NOLINT
+
+namespace sherpa_onnx {
+
+#ifdef _MSC_VER
+// See
+// https://stackoverflow.com/questions/2573834/c-convert-string-or-char-to-wstring-or-wchar-t
+static std::wstring ToWide(const std::string &s) {
+  std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
+  return converter.from_bytes(s);
+}
+#define SHERPA_MAYBE_WIDE(s) ToWide(s)
+#else
+#define SHERPA_MAYBE_WIDE(s) s
+#endif
+
+/**
+ * Get the input names of a model.
+ *
+ * @param sess An onnxruntime session.
+ * @param input_names. On return, it contains the input names of the model.
+ * @param input_names_ptr. On return, input_names_ptr[i] contains
+ *                         input_names[i].c_str()
+ */
+void GetInputNames(Ort::Session *sess, std::vector<std::string> *input_names,
+                   std::vector<const char *> *input_names_ptr);
+
+/**
+ * Get the output names of a model.
+ *
+ * @param sess An onnxruntime session.
+ * @param output_names. On return, it contains the output names of the model.
+ * @param output_names_ptr. On return, output_names_ptr[i] contains
+ *                         output_names[i].c_str()
+ */
+void GetOutputNames(Ort::Session *sess, std::vector<std::string> *output_names,
+                    std::vector<const char *> *output_names_ptr);
+
+void PrintModelMetadata(std::ostream &os,
+                        const Ort::ModelMetadata &meta_data);  // NOLINT
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_ONNX_UTILS_H_