[Util] add a first version of npy2apintstream fxns, untested

src/finn/data/cpp/npy2apintstream.hpp

+#include "cnpy.h"
+#include <vector>
+
+template <typename PackedT, typename ElemT, int ElemBits>
+npy2apintstream(const char * npy_path, hls::stream<PackedT> & out_stream) {
+  cnpy::NpyArray arr = cnpy::npy_load(npy_path);
+  float* loaded_data = arr.data<float>();
+  size_t outer_dim_elems = 1;
+  for(size_t dim = 0; dim < arr.shape.size()-1; dim++) {
+    outer_dim_elems *= arr.shape[dim];
+  }
+  size_t inner_dim_elems = arr.shape[arr.shape.size()-1];
+  for(size_t outer_elem = 0; outer_elem < outer_dim_elems; outer_elem++) {
+    PackedT packed_elem = 0;
+    for(size_t i = 0; i < inner_dim_elems; i++) {
+      packed_elem((i+1)*ElemBits-1, i*ElemBits) = (ElemT)(*loaded_data);
+      loaded_data++;
+    }
+    out_stream << packed_elem;
+  }
+}
+
+template <typename PackedT, typename ElemT, int ElemBits>
+apintstream2npy(hls::stream<PackedT> & in_stream, const std::vector<size_t> & shape, const char * npy_path) {
+  std::vector<float> data_to_save;
+  size_t outer_dim_elems = 1;
+  for(size_t dim = 0; dim < shape.size()-1; dim++) {
+    outer_dim_elems *= shape[dim];
+  }
+  size_t inner_dim_elems = shape[shape.size()-1];
+
+  for(size_t outer_elem = 0; outer_elem < outer_dim_elems; outer_elem++) {
+    PackedT packed_elem;
+    in_stream >> packed_elem;
+    for(size_t i = 0; i < inner_dim_elems; i++) {
+      data_to_save.push_back((float) packed_elem((i+1)*ElemBits-1, i*ElemBits));
+    }
+  }
+  cnpy::npy_save(npy_path, &data_to_save[0], shape, "w");
+}