Parse size as long

ddrio.c

@@ -90,7 +90,7 @@ parse_options (int argc, char *const *argv, Options *opts)
                 opts->output = optarg;
                 break;
             case OPT_SIZE:
-                opts->size = (size_t) atoi (optarg);
+                opts->size = (size_t) atol (optarg);
                 break;
             case OPT_COPY:
                 if (!strcmp (optarg, "memcpy"))