-int line, j;
-size_t to_copy = (size_t)(sizeof(chtype) * (win->_maxx + 1));
-
- TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %d, %d)", win, n, top,bottom));
-
- /*
- * This used to do a line-text pointer-shuffle instead of text copies.
- * That (a) doesn't work when the window is derived and doesn't have
- * its own storage, (b) doesn't save you a lot on modern machines
- * anyway. Your typical memcpy implementations are coded in
- * assembler using a tight BLT loop; for the size of copies we're
- * talking here, the total execution time is dominated by the one-time
- * setup cost. So there is no point in trying to be excessively
- * clever -- esr.
- */
-
- /* shift n lines downwards */
- if (n < 0) {
- for (line = bottom; line >= top-n; line--) {
- memcpy(win->_line[line].text,
- win->_line[line+n].text,
- to_copy);
- if_USE_SCROLL_HINTS(win->_line[line].oldindex = win->_line[line+n].oldindex);
- }
- for (line = top; line < top-n; line++) {
- for (j = 0; j <= win->_maxx; j ++)
- win->_line[line].text[j] = blank;
- if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
- }
- }
-
- /* shift n lines upwards */
- if (n > 0) {
- for (line = top; line <= bottom-n; line++) {
- memcpy(win->_line[line].text,
- win->_line[line+n].text,
- to_copy);
- if_USE_SCROLL_HINTS(win->_line[line].oldindex = win->_line[line+n].oldindex);
- }
- for (line = bottom; line > bottom-n; line--) {
- for (j = 0; j <= win->_maxx; j ++)
- win->_line[line].text[j] = blank;
- if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
- }
+ int limit;
+ int line;
+ int j;
+ size_t to_copy = (sizeof(NCURSES_CH_T) * (size_t) (win->_maxx + 1));
+
+ TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %ld, %ld)",
+ (void *) win, n, (long) top, (long) bottom));
+
+ if (top < 0
+ || bottom < top
+ || bottom > win->_maxy) {
+ TR(TRACE_MOVE, ("nothing to scroll"));
+ return;
+ }
+
+ /*
+ * This used to do a line-text pointer-shuffle instead of text copies.
+ * That (a) doesn't work when the window is derived and doesn't have
+ * its own storage, (b) doesn't save you a lot on modern machines
+ * anyway. Your typical memcpy implementations are coded in
+ * assembler using a tight BLT loop; for the size of copies we're
+ * talking here, the total execution time is dominated by the one-time
+ * setup cost. So there is no point in trying to be excessively
+ * clever -- esr.
+ */
+
+ /* shift n lines downwards */
+ if (n < 0) {
+ limit = top - n;
+ for (line = bottom; line >= limit && line >= 0; line--) {
+ TR(TRACE_MOVE, ("...copying %d to %d", line + n, line));
+ memcpy(win->_line[line].text,
+ win->_line[line + n].text,
+ to_copy);
+ if_USE_SCROLL_HINTS(win->_line[line].oldindex =
+ win->_line[line + n].oldindex);
+ }
+ for (line = top; line < limit && line <= win->_maxy; line++) {
+ TR(TRACE_MOVE, ("...filling %d", line));
+ for (j = 0; j <= win->_maxx; j++)
+ win->_line[line].text[j] = blank;
+ if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);