Support cross compiling for aarch64 (#52)

sherpa-onnx/csrc/alsa.h

@@ -0,0 +1,46 @@
+// sherpa-onnx/csrc/sherpa-alsa.h
+//
+// Copyright (c)  2022-2023  Xiaomi Corporation
+
+#ifndef SHERPA_ONNX_CSRC_ALSA_H_
+#define SHERPA_ONNX_CSRC_ALSA_H_
+
+#include <memory>
+#include <vector>
+
+#include "alsa/asoundlib.h"
+#include "sherpa-onnx/csrc/resample.h"
+
+namespace sherpa_onnx {
+
+class Alsa {
+ public:
+  explicit Alsa(const char *device_name);
+  ~Alsa();
+
+  // This is a blocking read.
+  //
+  // @param num_samples  Number of samples to read.
+  //
+  // The returned value is valid until the next call to Read().
+  const std::vector<float> &Read(int32_t num_samples);
+
+  int32_t GetExpectedSampleRate() const { return expected_sample_rate_; }
+  int32_t GetActualSampleRate() const { return actual_sample_rate_; }
+
+ private:
+  snd_pcm_t *capture_handle_;
+  int32_t expected_sample_rate_ = 16000;
+  int32_t actual_sample_rate_;
+
+  int32_t actual_channel_count_ = 1;
+
+  std::unique_ptr<LinearResample> resampler_;
+  std::vector<int16_t> samples_;  // directly from the microphone
+  std::vector<float> samples1_;   // normalized version of samples_
+  std::vector<float> samples2_;   // possibly resampled from samples1_
+};
+
+}  // namespace sherpa_onnx
+
+#endif  // SHERPA_ONNX_CSRC_ALSA_H_