Draft: C++ port of horizontal/mo_lib_gradients.F90

Port the functions of mo_lib_gradients.F90 to C++, with C bindings. Untested, but compiles.

src/horizontal/mo_lib_gradients.cpp

@@ -66,3 +66,60 @@ void grad_fd_norm_lib(const T* psi_c,
     }
 }
 
+// Computes directional derivative of a vertex centered variable with
+// respect to direction tangent to triangle edge. Notice that the
+// tangential direction is defined by: iorient*(vertex2 - vertex1)
+//  input: lives on vertices of triangles
+//  output: lives on edges (velocity points)
+template <typename T>
+void grad_fd_norm_lib(const T* psi_v,
+                      const int* edge_vertex_idx, const int* edge_vertex_blk,
+                      const T* primal_edge_length, const T* tangent_orientation,
+                      T* grad_tang_psi_e,
+                      // Integer parameters
+                      int i_startblk, int i_endblk,
+                      int i_startidx_in, int i_endidx_in,
+                      int slev, int elev, int nproma,
+                      // Extra array dimension
+                      int nlev, int nblks_v, int nblks_e,
+                      // OpenACC flag
+                      bool lacc)
+{
+    // Host or device check
+
+    // Wrap raw pointers in unmanaged Kokkos views
+    typedef Kokkos::View<const T***, Kokkos::LayoutLeft, Kokkos::MemoryUnmanaged> UnmanagedConstT3D;
+    typedef Kokkos::View<const int***, Kokkos::LayoutLeft, Kokkos::MemoryUnmanaged> UnmanagedConstInt3D;
+    typedef Kokkos::View<const int**, Kokkos::LayoutLeft, Kokkos::MemoryUnmanaged> UnmanagedConstT2D;
+    typedef Kokkos::View<T***, Kokkos::LayoutLeft, Kokkos::MemoryUnmanaged> UnmanagedT3D;
+
+    UnmanagedConstT3D psi_v_view(psi_v, nproma, nlev, nblks_v);
+    UnmanagedConstInt3D edge_vertex_idx_view(edge_vertex_idx, nproma, nblks_e, 2);
+    UnmanagedConstInt3D edge_vertex_blk_view(edge_vertex_blk, nproma, nblks_e, 2);
+    UnmanagedConstT2D primal_edge_length_view(primal_edge_length, nproma, nblks_e);
+    UnmanagedConstT2D tangent_orientation_view(tangent_orientation, nproma, nblks_e);
+    UnmanagedT3D grad_tang_psi_e_view(grad_tang_psi_e, nproma, nlev, nblks_e);
+
+    for (int jb = i_startblk; jb < i_endblk; ++jb)
+    {
+        int i_startidx, i_endidx;
+        get_indices_e_lib(i_startidx_in, i_endidx_in, nproma, jb,
+                          i_startblk, i_endblk, i_startidx, i_endidx);
+
+        Kokkos::MDRangePolicy<Kokkos::Rank<2>> innerPolicy({slev, i_startidx},
+                                                           {elev, i_endidx});
+        Kokkos::parallel_for("grad_fd_norm_lib_inner", innerPolicy,
+                             KOKKOS_LAMBDA(const int jk, const int je)
+        {
+            grad_tang_psi_e_view(je, jk, jb) =
+                tangent_orientation_view(je, jb) *
+                (psi_v_view(edge_vertex_idx_view(je, jb, 1), jk, edge_vertex_blk_view(je, jb, 1)) -
+                 psi_v_view(edge_vertex_idx_view(je, jb, 0), jk, edge_vertex_blk_view(je, jb, 0))) /
+                primal_edge_length_view(je, jb);
+        });
+        // Is a barrier needed here?
+        // Kokkos::fence();
+    }
+}
+
+