-typedef unsigned char _pdata * va_list ;
-#define va_arg(marker,type) *((type _data * )(marker -= sizeof(type)))
-#define va_start(marker,first) { marker = (va_list) ((char _pdata * )&first) ; }
+typedef unsigned char * va_list;
+#define va_start(list, last) list = (unsigned char *)&last + sizeof(last)
+#define va_arg(list, type) *((type *)((list += sizeof(type)) - sizeof(type)))
+
+#elif defined(__ds390) || defined(__ds400)
+
+typedef unsigned char * va_list ;
+#define va_arg(marker,type) *((type *)(marker -= sizeof(type)))
+#define va_start(marker,first) { marker = &first; }
+
+#elif defined(SDCC_USE_XSTACK)
+
+typedef unsigned char pdata * va_list ;
+#define va_arg(marker,type) *((type data *)(marker -= sizeof(type)))
+#define va_start(marker,first) { marker = (va_list)((char pdata *)&first); }