Add `FMPI_PRIV_FUTHARK_FUNC_IDX()`

include/internal/generic/fmpi_futhark_generic.h

@@ -42,8 +42,11 @@ struct fmpi_futhark_ctx;
 #define FMPI_FUTHARK_TYPES \
     FMPI_TYPE_REAL
 
+#define FMPI_PRIV_FUTHARK_FUNC_IDX(d, t) \
+    (((t) * FMPI_DIM_MAX) + (d) - 1)
+
 #define FMPI_PRIV_FUTHARK_ARRAY_ENTRY(D, T) \
-    [FMPI_TYPE_##T * (FMPI_DIM_MAX) + ((D)-1)] = fmpi_futhark_new_##D##d_##T
+    [FMPI_PRIV_FUTHARK_FUNC_IDX(D, FMPI_TYPE_##T)] = fmpi_futhark_new_##D##d_##T
 
 #define FMPI_FUTHARK_ARRAY_ENTRY_LIST(D) \
     CPL_MAP_FIXED(FMPI_PRIV_FUTHARK_ARRAY_ENTRY, CPL_COMMA, (D), FMPI_FUTHARK_TYPES)

src/fmpi_futhark.c

@@ -148,7 +148,7 @@ void * fmpi_futhark_new_data(
     assert(ctx != NULL);
     assert(data != NULL);
     assert(dim_cnt <= FMPI_DIM_MAX);
-    const size_t idx = (type * (FMPI_DIM_MAX) + ((dim_cnt)-1));
+    const size_t idx = FMPI_PRIV_FUTHARK_FUNC_IDX(dim_cnt, type);
     return fmpi_futhark_new_data_func_list[idx](ctx, data, x, y, z);
 }