+#if HAVE_WCSRTOMBS
+#define count_wchars(src, len, state) wcsrtombs(0, &src, len, state)
+#define trans_wchars(dst, src, len, state) wcsrtombs(dst, &src, len, state)
+#define reset_wchars(state) memset(&state, 0, sizeof(state))
+#elif HAVE_WCSTOMBS && HAVE_MBTOWC && HAVE_MBLEN
+#define count_wchars(src, len, state) wcstombs(0, src, len)
+#define trans_wchars(dst, src, len, state) wcstombs(dst, src, len)
+#define reset_wchars(state) mblen(NULL, 0), mbtowc(NULL, NULL, 0)
+#define state_unused
+#endif
+
+#if HAVE_MBSRTOWCS
+#define count_mbytes(src, len, state) mbsrtowcs(0, &src, len, state)
+#define trans_mbytes(dst, src, len, state) mbsrtowcs(dst, &src, len, state)
+#define reset_mbytes(state) memset(&state, 0, sizeof(state))
+#elif HAVE_MBSTOWCS && HAVE_MBTOWC && HAVE_MBLEN
+#define count_mbytes(src, len, state) mbstowcs(0, src, len)
+#define trans_mbytes(dst, src, len, state) mbstowcs(dst, src, len)
+#define reset_mbytes(state) mblen(NULL, 0), mbtowc(NULL, NULL, 0)
+#define state_unused
+#endif
+