From 7cf924a174a509bee2162169adc5c82d011c7116 Mon Sep 17 00:00:00 2001
From: Tyge Lovset <tylovset@gmail.com>
Date: Mon, 21 Aug 2023 08:58:24 +0200
Subject: Added kokkos submdspan example (did not make it to c++23).

---
 misc/examples/spans/submdspan.c | 44 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 misc/examples/spans/submdspan.c

diff --git a/misc/examples/spans/submdspan.c b/misc/examples/spans/submdspan.c
new file mode 100644
index 00000000..fa0d5762
--- /dev/null
+++ b/misc/examples/spans/submdspan.c
@@ -0,0 +1,44 @@
+// https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2630r0.html
+// C99:
+#include <stdio.h>
+#include <stc/cspan.h>
+
+using_cspan3(span, double); // define span, span2, span3
+
+// Set all elements of a rank-2 mdspan to zero.
+void zero_2d(span2 grid2d) {
+  c_static_assert(cspan_rank(&grid2d) == 2);
+  for (int i = 0; i < grid2d.shape[0]; ++i) {
+    for (int j = 0; j < grid2d.shape[1]; ++j) {
+      *cspan_at(&grid2d, i,j) = 0;
+    }
+  }
+}
+
+void zero_surface(span3 grid3d) {
+  c_static_assert(cspan_rank(&grid3d) == 3);
+  zero_2d(cspan_slice(span2, &grid3d, {0}, {c_ALL}, {c_ALL}));
+  zero_2d(cspan_slice(span2, &grid3d, {c_ALL}, {0}, {c_ALL}));
+  zero_2d(cspan_slice(span2, &grid3d, {c_ALL}, {c_ALL}, {0}));
+  zero_2d(cspan_slice(span2, &grid3d, {grid3d.shape[0]-1}, {c_ALL}, {c_ALL}));
+  zero_2d(cspan_slice(span2, &grid3d, {c_ALL}, {grid3d.shape[1]-1}, {c_ALL}));
+  zero_2d(cspan_slice(span2, &grid3d, {c_ALL}, {c_ALL}, {grid3d.shape[2]-1}));
+}
+
+int main() {
+  double arr[3*4*5];
+  for (int i=0; i<c_arraylen(arr); ++i) arr[i] = i + 1.0;
+
+  span3 md = cspan_md(arr, 3, 4, 5);
+
+  zero_surface(md);
+
+  for (int i = 0; i < md.shape[0]; i++) {
+    for (int j = 0; j < md.shape[1]; j++) {
+      for (int k = 0; k < md.shape[2]; k++)
+        printf(" %2g", *cspan_at(&md, i,j,k));
+      puts("");
+    }
+    puts("");
+  }
+}
\ No newline at end of file
-- 
cgit v1.2.3