Added algo/cmspan.h: multi-dim span, similar to c++23 mdspan. May get some API changes. Changed cspan.h, these may merge.

1 files changed, 49 insertions, 0 deletions

diff --git a/misc/examples/multidim.c b/misc/examples/multidim.c
new file mode 100644
index 00000000..044693be
--- /dev/null
+++ b/misc/examples/multidim.c
@@ -0,0 +1,49 @@
+// Example from https://en.cppreference.com/w/cpp/container/mdspan
+#define i_val int
+#include <stc/cstack.h>
+#include <stc/algo/cmspan.h>
+#include <stdio.h>
+using_cmspan(ispan1, int, 1);
+using_cmspan(ispan2, int, 2);
+using_cmspan(ispan3, int, 3);
+ 
+int main()
+{
+  cstack_int v = {0};
+  c_FORLIST (i, unsigned, {1,2,3,4,5,6,7,8,9,10,11,12})
+    cstack_int_push(&v, *i.ref);
+
+  // View data as contiguous memory representing 12 ints
+  ispan1 ms1 = cmspan_make(v.data, 12);
+  // View data as contiguous memory representing 2 rows of 6 ints each
+  ispan2 ms2 = cmspan_make(v.data, 2, 6);
+  // View the same data as a 3D array 2 x 3 x 2
+  ispan3 ms3 = cmspan_make(v.data, 2, 3, 2);
+
+  // write data using 2D view
+  for(unsigned i=0; i != ms2.dim[0]; i++)
+    for(unsigned j=0; j != ms2.dim[1]; j++)
+      *cmspan_at(&ms2, i, j) = i*1000 + j;
+
+  // print data using 1D view
+  for(unsigned i=0; i != ms1.dim[0]; i++)
+    printf(" %d", *cmspan_at(&ms1, i));
+  puts("");
+
+  c_FOREACH (i, ispan1, ms1)
+    printf(" %d", *i.ref);
+  puts("");
+
+  // read back using 3D view
+  for(unsigned i=0; i != ms3.dim[0]; i++)
+  {
+    printf("slice @ i = %u\n", i);
+    for(unsigned j=0; j != ms3.dim[1]; j++)
+    {
+      for(unsigned k=0; k != ms3.dim[2]; k++)
+        printf("%d ", *cmspan_at(&ms3, i, j, k));
+      puts("");
+    }
+  }
+  cstack_int_drop(&v);
+}