Support slicing a shallow copy of a 3-d tensor (#83)

sherpa-onnx/csrc/slice.cc

@@ -0,0 +1,34 @@
+// sherpa-onnx/csrc/slice.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/slice.h"
+
+#include <assert.h>
+
+#include <vector>
+
+namespace sherpa_onnx {
+
+template <typename T /*=float*/>
+Ort::Value Slice(const Ort::Value *v, int32_t dim0, int32_t dim1_start,
+                 int32_t dim1_end) {
+  std::vector<int64_t> shape = v->GetTensorTypeAndShapeInfo().GetShape();
+  assert(shape.size() == 3);
+
+  auto memory_info =
+      Ort::MemoryInfo::CreateCpu(OrtDeviceAllocator, OrtMemTypeDefault);
+
+  std::array<int64_t, 2> ans_shape{dim1_end - dim1_start, shape[2]};
+  const T *src = v->GetTensorData<T>();
+  src += dim0 * shape[1] * shape[2] + dim1_start * shape[2];
+
+  return Ort::Value::CreateTensor(memory_info, const_cast<T *>(src),
+                                  ans_shape[0] * ans_shape[1], ans_shape.data(),
+                                  ans_shape.size());
+}
+
+template Ort::Value Slice<float>(const Ort::Value *v, int32_t dim0,
+                                 int32_t dim1_start, int32_t dim1_end);
+
+}  // namespace sherpa_onnx