add example5 - simple stencil2d (#6)

* add example5 - simple stencil2d

* review fixes

change to a floating point number
remove unused variables

.github/workflows/docker_workflow.yml

@@ -47,6 +47,8 @@ jobs:
           cmake --build build -j
       - name: Run examples
         run: |
-          mpirun -n 2 ./build/src/example1
-          mpirun -n 2 ./build/src/example2
-          mpirun -n 2 ./build/src/example3
+          mpirun -n 3 ./build/src/example1
+          mpirun -n 3 ./build/src/example2
+          mpirun -n 3 ./build/src/example3
+          mpirun -n 3 ./build/src/example4
+          mpirun -n 3 ./build/src/example5

scripts/build_run.sh

@@ -13,3 +13,5 @@ cmake --build build -j
 mpirun -n 2 ./build/src/example1
 mpirun -n 2 ./build/src/example2
 mpirun -n 2 ./build/src/example3
+mpirun -n 2 ./build/src/example4
+mpirun -n 2 ./build/src/example5

src/CMakeLists.txt

@@ -31,3 +31,8 @@ add_executable(example4 example4.cpp)
 
 target_compile_definitions(example4 INTERFACE DR_FORMAT)
 target_link_libraries(example4 DR::mpi fmt::fmt)
+
+add_executable(example5 example5.cpp)
+
+target_compile_definitions(example5 INTERFACE DR_FORMAT)
+target_link_libraries(example5 DR::mpi fmt::fmt)

src/example5.cpp

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: Intel Corporation
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <dr/mhp.hpp>
+#include <fmt/core.h>
+
+namespace mhp = dr::mhp;
+
+using T = float;
+using MDA = dr::mhp::distributed_mdarray<T, 2>;
+
+/* 2d stencil - simple operation on multi-dimensional array */
+int main() {
+  mhp::init(sycl::default_selector_v);
+
+  std::size_t arr_size = 4;
+  std::size_t radius = 1;
+  std::array slice_starts{radius, radius};
+  std::array slice_ends{arr_size - radius, arr_size - radius};
+
+  auto dist = dr::mhp::distribution().halo(radius);
+  MDA a({arr_size, arr_size}, dist);
+  MDA b({arr_size, arr_size}, dist);
+  mhp::iota(a, 1);
+  mhp::iota(b, 1);
+
+  auto in = dr::mhp::views::submdspan(a.view(), slice_starts, slice_ends);
+  auto out = dr::mhp::views::submdspan(b.view(), slice_starts, slice_ends);
+
+  auto mdspan_stencil_op = [](auto &&v) {
+    auto [in, out] = v;
+    out(0, 0) = (in(-1, 0) + in(0, -1) + in(0, 0) + in(0, 1) + in(1, 0)) / 4;
+  };
+
+  mhp::halo(a).exchange();
+  mhp::stencil_for_each(mdspan_stencil_op, in, out);
+
+  if (mhp::rank() == 0) {
+    fmt::print("a: \n{} \n", a.mdspan());
+    fmt::print("b: \n{} \n", b.mdspan());
+    fmt::print("in: \n{} \n", in.mdspan());
+    fmt::print("out: \n{} \n", out.mdspan());
+  }
+
+  mhp::finalize();
+
+  return 0;
+}