+static bool
+newline_forces_scroll(WINDOW *win, NCURSES_SIZE_T * ypos)
+{
+ bool result = FALSE;
+
+ if (*ypos >= win->_regtop && *ypos == win->_regbottom) {
+ *ypos = win->_regbottom;
+ result = TRUE;
+ } else {
+ *ypos = (NCURSES_SIZE_T) (*ypos + 1);
+ }
+ return result;
+}
+
+/*
+ * The _WRAPPED flag is useful only for telling an application that we've just
+ * wrapped the cursor. We don't do anything with this flag except set it when
+ * wrapping, and clear it whenever we move the cursor. If we try to wrap at
+ * the lower-right corner of a window, we cannot move the cursor (since that
+ * wouldn't be legal). So we return an error (which is what SVr4 does).
+ * Unlike SVr4, we can successfully add a character to the lower-right corner
+ * (Solaris 2.6 does this also, however).
+ */
+static int
+wrap_to_next_line(WINDOW *win)
+{
+ win->_flags |= _WRAPPED;
+ if (newline_forces_scroll(win, &(win->_cury))) {
+ win->_curx = win->_maxx;
+ if (!win->_scroll)
+ return (ERR);
+ scroll(win);
+ }
+ win->_curx = 0;
+ return (OK);
+}
+
+#if USE_WIDEC_SUPPORT
+static int waddch_literal(WINDOW *, NCURSES_CH_T);
+/*
+ * Fill the given number of cells with blanks using the current background
+ * rendition. This saves/restores the current x-position.
+ */
+static void
+fill_cells(WINDOW *win, int count)
+{
+ NCURSES_CH_T blank = blankchar;
+ int save_x = win->_curx;
+ int save_y = win->_cury;
+
+ while (count-- > 0) {
+ if (waddch_literal(win, blank) == ERR)
+ break;
+ }
+ win->_curx = (NCURSES_SIZE_T) save_x;
+ win->_cury = (NCURSES_SIZE_T) save_y;
+}
+#endif
+
+/*
+ * Build up the bytes for a multibyte character, returning the length when
+ * complete (a positive number), -1 for error and -2 for incomplete.
+ */
+#if USE_WIDEC_SUPPORT
+NCURSES_EXPORT(int)
+_nc_build_wch(WINDOW *win, ARG_CH_T ch)
+{
+ char *buffer = WINDOW_EXT(win, addch_work);
+ int len;
+ int x = win->_curx;
+ int y = win->_cury;
+ mbstate_t state;
+ wchar_t result;
+
+ if ((WINDOW_EXT(win, addch_used) != 0) &&
+ (WINDOW_EXT(win, addch_x) != x ||
+ WINDOW_EXT(win, addch_y) != y)) {
+ /* discard the incomplete multibyte character */
+ WINDOW_EXT(win, addch_used) = 0;
+ TR(TRACE_VIRTPUT,
+ ("Alert discarded multibyte on move (%d,%d) -> (%d,%d)",
+ WINDOW_EXT(win, addch_y), WINDOW_EXT(win, addch_x),
+ y, x));
+ }
+ WINDOW_EXT(win, addch_x) = x;
+ WINDOW_EXT(win, addch_y) = y;
+
+ init_mb(state);
+ buffer[WINDOW_EXT(win, addch_used)] = (char) CharOf(CHDEREF(ch));
+ WINDOW_EXT(win, addch_used) += 1;
+ buffer[WINDOW_EXT(win, addch_used)] = '\0';
+ if ((len = (int) mbrtowc(&result,
+ buffer,
+ (size_t) WINDOW_EXT(win, addch_used),
+ &state)) > 0) {
+ attr_t attrs = AttrOf(CHDEREF(ch));
+ if_EXT_COLORS(int pair = GetPair(CHDEREF(ch)));
+ SetChar(CHDEREF(ch), result, attrs);
+ if_EXT_COLORS(SetPair(CHDEREF(ch), pair));
+ WINDOW_EXT(win, addch_used) = 0;
+ } else if (len == -1) {
+ /*
+ * An error occurred. We could either discard everything,
+ * or assume that the error was in the previous input.
+ * Try the latter.
+ */
+ TR(TRACE_VIRTPUT, ("Alert! mbrtowc returns error"));
+ /* handle this with unctrl() */
+ WINDOW_EXT(win, addch_used) = 0;
+ }
+ return len;
+}
+#endif /* USE_WIDEC_SUPPORT */
+
+static
+#if !USE_WIDEC_SUPPORT /* cannot be inline if it is recursive */
+NCURSES_INLINE
+#endif
+int