+#ifdef OPTIMISE_SCROLL
+/*
+ * Scroll the physical display, and our conception of it in disptext.
+ */
+static void scroll_display(Terminal *term, int topline, int botline, int lines)
+{
+ unsigned long *start, *end;
+ int distance, size, i;
+
+ start = term->disptext + topline * (term->cols + 1);
+ end = term->disptext + (botline + 1) * (term->cols + 1);
+ distance = (lines > 0 ? lines : -lines) * (term->cols + 1);
+ size = end - start - distance;
+ if (lines > 0) {
+ memmove(start, start + distance, size * TSIZE);
+ if (term->dispcurs >= start + distance &&
+ term->dispcurs <= start + distance + size)
+ term->dispcurs -= distance;
+ for (i = 0; i < distance; i++)
+ (start + size)[i] |= ATTR_INVALID;
+ } else {
+ memmove(start + distance, start, size * TSIZE);
+ if (term->dispcurs >= start && term->dispcurs <= start + size)
+ term->dispcurs += distance;
+ for (i = 0; i < distance; i++)
+ start[i] |= ATTR_INVALID;
+ }
+ do_scroll(term->frontend, topline, botline, lines);
+}
+#endif /* OPTIMISE_SCROLL */
+