+=cut
+*/
+
+/*
+=for apidoc is_ascii_string
+
+Returns true if first C<len> bytes of the given string are ASCII (i.e. none
+of them even raise the question of UTF-8-ness).
+
+See also is_utf8_string(), is_utf8_string_loclen(), and is_utf8_string_loc().
+
+=cut
+*/
+
+bool
+Perl_is_ascii_string(const U8 *s, STRLEN len)
+{
+ const U8* const send = s + (len ? len : strlen((const char *)s));
+ const U8* x = s;
+
+ PERL_ARGS_ASSERT_IS_ASCII_STRING;
+
+ for (; x < send; ++x) {
+ if (!UTF8_IS_INVARIANT(*x))
+ break;
+ }
+
+ return x == send;
+}
+
+/*
+=for apidoc uvuni_to_utf8_flags