--- a/src/move.c
+++ b/src/move.c
@@ -1,3634 +1,3634 @@
-/* vi:set ts=8 sts=4 sw=4 noet:
- *
- * VIM - Vi IMproved	by Bram Moolenaar
- *
- * Do ":help uganda"  in Vim to read copying and usage conditions.
- * Do ":help credits" in Vim to see a list of people who contributed.
- * See README.txt for an overview of the Vim source code.
- */
-/*
- * move.c: Functions for moving the cursor and scrolling text.
- *
- * There are two ways to move the cursor:
- * 1. Move the cursor directly, the text is scrolled to keep the cursor in the
- *    window.
- * 2. Scroll the text, the cursor is moved into the text visible in the
- *    window.
- * The 'scrolloff' option makes this a bit complicated.
- */
-
-#include "vim.h"
-
-static int scrolljump_value(void);
-static int check_top_offset(void);
-static void curs_rows(win_T *wp);
-
-typedef struct
-{
-    linenr_T	    lnum;	// line number
-#ifdef FEAT_DIFF
-    int		    fill;	// filler lines
-#endif
-    int		    height;	// height of added line
-} lineoff_T;
-
-static void topline_back(lineoff_T *lp);
-static void botline_forw(lineoff_T *lp);
-
-/*
- * Reduce "n" for the screen lines skipped with "wp->w_skipcol".
- */
-    int
-adjust_plines_for_skipcol(win_T *wp, int n)
-{
-    if (wp->w_skipcol == 0)
-	return n;
-
-    int off = 0;
-    int width = wp->w_width - win_col_off(wp);
-    if (wp->w_skipcol >= width)
-    {
-	++off;
-	int skip = wp->w_skipcol - width;
-	width += win_col_off2(wp);
-	while (skip >= width)
-	{
-	    ++off;
-	    skip -= width;
-	}
-    }
-    wp->w_valid &= ~VALID_WROW;
-    return n - off;
-}
-
-/*
- * Return how many lines "lnum" will take on the screen, taking into account
- * whether it is the first line, whether w_skipcol is non-zero and limiting to
- * the window height.
- */
-    static int
-plines_correct_topline(win_T *wp, linenr_T lnum)
-{
-    int n;
-#ifdef FEAT_DIFF
-    if (lnum == wp->w_topline)
-	n = plines_win_nofill(wp, lnum, FALSE) + wp->w_topfill;
-    else
-#endif
-	n = plines_win(wp, lnum, FALSE);
-    if (lnum == wp->w_topline)
-	n = adjust_plines_for_skipcol(wp, n);
-    if (n > wp->w_height)
-	n = wp->w_height;
-    return n;
-}
-
-/*
- * Compute wp->w_botline for the current wp->w_topline.  Can be called after
- * wp->w_topline changed.
- */
-    static void
-comp_botline(win_T *wp)
-{
-    int		n;
-    linenr_T	lnum;
-    int		done;
-#ifdef FEAT_FOLDING
-    linenr_T    last;
-    int		folded;
-#endif
-
-    /*
-     * If w_cline_row is valid, start there.
-     * Otherwise have to start at w_topline.
-     */
-    check_cursor_moved(wp);
-    if (wp->w_valid & VALID_CROW)
-    {
-	lnum = wp->w_cursor.lnum;
-	done = wp->w_cline_row;
-    }
-    else
-    {
-	lnum = wp->w_topline;
-	done = 0;
-    }
-
-    for ( ; lnum <= wp->w_buffer->b_ml.ml_line_count; ++lnum)
-    {
-#ifdef FEAT_FOLDING
-	last = lnum;
-	folded = FALSE;
-	if (hasFoldingWin(wp, lnum, NULL, &last, TRUE, NULL))
-	{
-	    n = 1;
-	    folded = TRUE;
-	}
-	else
-#endif
-	{
-	    n = plines_correct_topline(wp, lnum);
-	}
-	if (
-#ifdef FEAT_FOLDING
-		lnum <= wp->w_cursor.lnum && last >= wp->w_cursor.lnum
-#else
-		lnum == wp->w_cursor.lnum
-#endif
-	   )
-	{
-	    wp->w_cline_row = done;
-	    wp->w_cline_height = n;
-#ifdef FEAT_FOLDING
-	    wp->w_cline_folded = folded;
-#endif
-	    redraw_for_cursorline(wp);
-	    wp->w_valid |= (VALID_CROW|VALID_CHEIGHT);
-	}
-	if (done + n > wp->w_height)
-	    break;
-	done += n;
-#ifdef FEAT_FOLDING
-	lnum = last;
-#endif
-    }
-
-    // wp->w_botline is the line that is just below the window
-    wp->w_botline = lnum;
-    wp->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
-
-    set_empty_rows(wp, done);
-}
-
-/*
- * Redraw when w_cline_row changes and 'relativenumber' or 'cursorline' is
- * set.
- */
-    void
-redraw_for_cursorline(win_T *wp)
-{
-    if ((wp->w_p_rnu
-#ifdef FEAT_SYN_HL
-		|| wp->w_p_cul
-#endif
-		)
-	    && (wp->w_valid & VALID_CROW) == 0
-	    && !pum_visible())
-    {
-	// win_line() will redraw the number column and cursorline only.
-	redraw_win_later(wp, UPD_VALID);
-    }
-}
-
-#ifdef FEAT_SYN_HL
-/*
- * Redraw when w_virtcol changes and 'cursorcolumn' is set or 'cursorlineopt'
- * contains "screenline".
- */
-    static void
-redraw_for_cursorcolumn(win_T *wp)
-{
-    if ((wp->w_valid & VALID_VIRTCOL) == 0 && !pum_visible())
-    {
-	// When 'cursorcolumn' is set need to redraw with UPD_SOME_VALID.
-	if (wp->w_p_cuc)
-	    redraw_win_later(wp, UPD_SOME_VALID);
-	// When 'cursorlineopt' contains "screenline" need to redraw with
-	// UPD_VALID.
-	else if (wp->w_p_cul && (wp->w_p_culopt_flags & CULOPT_SCRLINE))
-	    redraw_win_later(wp, UPD_VALID);
-    }
-}
-#endif
-
-/*
- * Calculates how much the 'listchars' "precedes" or 'smoothscroll' "<<<"
- * marker overlaps with buffer text for window "wp".
- * Parameter "extra2" should be the padding on the 2nd line, not the first
- * line.
- * Returns the number of columns of overlap with buffer text, excluding the
- * extra padding on the ledge.
- */
-     int
-sms_marker_overlap(win_T *wp, int extra2)
-{
-#if defined(FEAT_LINEBREAK)
-    // There is no marker overlap when in showbreak mode, thus no need to
-    // account for it.  See wlv_screen_line().
-    if (*get_showbreak_value(wp) != NUL)
-	return 0;
-#endif
-    // Overlap when 'list' and 'listchars' "precedes" are set is 1.
-    if (wp->w_p_list && wp->w_lcs_chars.prec)
-	return 1;
-
-    return extra2 > 3 ? 0 : 3 - extra2;
-}
-
-/*
- * Calculates the skipcol offset for window "wp" given how many
- * physical lines we want to scroll down.
- */
-    static int
-skipcol_from_plines(win_T *wp, int plines_off)
-{
-    int width1 = wp->w_width - win_col_off(wp);
-
-    int skipcol = 0;
-    if (plines_off > 0)
-	skipcol += width1;
-    if (plines_off > 1)
-	skipcol += (width1 + win_col_off2(wp)) * (plines_off - 1);
-    return skipcol;
-}
-
-/*
- * Set curwin->w_skipcol to zero and redraw later if needed.
- */
-    static void
-reset_skipcol(void)
-{
-    if (curwin->w_skipcol == 0)
-	return;
-
-    curwin->w_skipcol = 0;
-
-    // Should use the least expensive way that displays all that changed.
-    // UPD_NOT_VALID is too expensive, UPD_REDRAW_TOP does not redraw
-    // enough when the top line gets another screen line.
-    redraw_later(UPD_SOME_VALID);
-}
-
-/*
- * Update curwin->w_topline and redraw if necessary.
- * Used to update the screen before printing a message.
- */
-    void
-update_topline_redraw(void)
-{
-    update_topline();
-    if (must_redraw)
-	update_screen(0);
-}
-
-/*
- * Update curwin->w_topline to move the cursor onto the screen.
- */
-    void
-update_topline(void)
-{
-    long	line_count;
-    int		halfheight;
-    int		n;
-#ifdef FEAT_FOLDING
-    linenr_T	lnum;
-#endif
-    int		check_topline = FALSE;
-    int		check_botline = FALSE;
-    long	*so_ptr = curwin->w_p_so >= 0 ? &curwin->w_p_so : &p_so;
-    int		save_so = *so_ptr;
-
-    // Cursor is updated instead when this is TRUE for 'splitkeep'.
-    if (skip_update_topline)
-	return;
-
-    // If there is no valid screen and when the window height is zero just use
-    // the cursor line.
-    if (!screen_valid(TRUE) || curwin->w_height == 0)
-    {
-	check_cursor_lnum();
-	curwin->w_topline = curwin->w_cursor.lnum;
-	curwin->w_botline = curwin->w_topline;
-	curwin->w_scbind_pos = 1;
-	return;
-    }
-
-    check_cursor_moved(curwin);
-    if (curwin->w_valid & VALID_TOPLINE)
-	return;
-
-    // When dragging with the mouse, don't scroll that quickly
-    if (mouse_dragging > 0)
-	*so_ptr = mouse_dragging - 1;
-
-    linenr_T old_topline = curwin->w_topline;
-#ifdef FEAT_DIFF
-    int old_topfill = curwin->w_topfill;
-#endif
-
-    /*
-     * If the buffer is empty, always set topline to 1.
-     */
-    if (BUFEMPTY())		// special case - file is empty
-    {
-	if (curwin->w_topline != 1)
-	    redraw_later(UPD_NOT_VALID);
-	curwin->w_topline = 1;
-	curwin->w_botline = 2;
-	curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
-	curwin->w_scbind_pos = 1;
-    }
-
-    /*
-     * If the cursor is above or near the top of the window, scroll the window
-     * to show the line the cursor is in, with 'scrolloff' context.
-     */
-    else
-    {
-	if (curwin->w_topline > 1 || curwin->w_skipcol > 0)
-	{
-	    // If the cursor is above topline, scrolling is always needed.
-	    // If the cursor is far below topline and there is no folding,
-	    // scrolling down is never needed.
-	    if (curwin->w_cursor.lnum < curwin->w_topline)
-		check_topline = TRUE;
-	    else if (check_top_offset())
-		check_topline = TRUE;
-	    else if (curwin->w_skipcol > 0
-				 && curwin->w_cursor.lnum == curwin->w_topline)
-	    {
-		colnr_T vcol;
-
-		// Check that the cursor position is visible.  Add columns for
-		// the marker displayed in the top-left if needed.
-		getvvcol(curwin, &curwin->w_cursor, &vcol, NULL, NULL);
-		int overlap = sms_marker_overlap(curwin, curwin_col_off()
-							- curwin_col_off2());
-		if (curwin->w_skipcol + overlap > vcol)
-		    check_topline = TRUE;
-	    }
-	}
-#ifdef FEAT_DIFF
-	    // Check if there are more filler lines than allowed.
-	if (!check_topline && curwin->w_topfill > diff_check_fill(curwin,
-							   curwin->w_topline))
-	    check_topline = TRUE;
-#endif
-
-	if (check_topline)
-	{
-	    halfheight = curwin->w_height / 2 - 1;
-	    if (halfheight < 2)
-		halfheight = 2;
-
-#ifdef FEAT_FOLDING
-	    if (hasAnyFolding(curwin))
-	    {
-		// Count the number of logical lines between the cursor and
-		// topline + scrolloff (approximation of how much will be
-		// scrolled).
-		n = 0;
-		for (lnum = curwin->w_cursor.lnum;
-				    lnum < curwin->w_topline + *so_ptr; ++lnum)
-		{
-		    ++n;
-		    // stop at end of file or when we know we are far off
-		    if (lnum >= curbuf->b_ml.ml_line_count || n >= halfheight)
-			break;
-		    (void)hasFolding(lnum, NULL, &lnum);
-		}
-	    }
-	    else
-#endif
-		n = curwin->w_topline + *so_ptr - curwin->w_cursor.lnum;
-
-	    // If we weren't very close to begin with, we scroll to put the
-	    // cursor in the middle of the window.  Otherwise put the cursor
-	    // near the top of the window.
-	    if (n >= halfheight)
-		scroll_cursor_halfway(FALSE, FALSE);
-	    else
-	    {
-		scroll_cursor_top(scrolljump_value(), FALSE);
-		check_botline = TRUE;
-	    }
-	}
-
-	else
-	{
-#ifdef FEAT_FOLDING
-	    // Make sure topline is the first line of a fold.
-	    (void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-	    check_botline = TRUE;
-	}
-    }
-
-    /*
-     * If the cursor is below the bottom of the window, scroll the window
-     * to put the cursor on the window.
-     * When w_botline is invalid, recompute it first, to avoid a redraw later.
-     * If w_botline was approximated, we might need a redraw later in a few
-     * cases, but we don't want to spend (a lot of) time recomputing w_botline
-     * for every small change.
-     */
-    if (check_botline)
-    {
-	if (!(curwin->w_valid & VALID_BOTLINE_AP))
-	    validate_botline();
-
-	if (curwin->w_botline <= curbuf->b_ml.ml_line_count)
-	{
-	    if (curwin->w_cursor.lnum < curwin->w_botline)
-	    {
-	      if (((long)curwin->w_cursor.lnum
-					   >= (long)curwin->w_botline - *so_ptr
-#ifdef FEAT_FOLDING
-			|| hasAnyFolding(curwin)
-#endif
-			))
-	      {
-		lineoff_T	loff;
-
-		// Cursor is (a few lines) above botline, check if there are
-		// 'scrolloff' window lines below the cursor.  If not, need to
-		// scroll.
-		n = curwin->w_empty_rows;
-		loff.lnum = curwin->w_cursor.lnum;
-#ifdef FEAT_FOLDING
-		// In a fold go to its last line.
-		(void)hasFolding(loff.lnum, NULL, &loff.lnum);
-#endif
-#ifdef FEAT_DIFF
-		loff.fill = 0;
-		n += curwin->w_filler_rows;
-#endif
-		loff.height = 0;
-		while (loff.lnum < curwin->w_botline
-#ifdef FEAT_DIFF
-			&& (loff.lnum + 1 < curwin->w_botline || loff.fill == 0)
-#endif
-			)
-		{
-		    n += loff.height;
-		    if (n >= *so_ptr)
-			break;
-		    botline_forw(&loff);
-		}
-		if (n >= *so_ptr)
-		    // sufficient context, no need to scroll
-		    check_botline = FALSE;
-	      }
-	      else
-		  // sufficient context, no need to scroll
-		  check_botline = FALSE;
-	    }
-	    if (check_botline)
-	    {
-#ifdef FEAT_FOLDING
-		if (hasAnyFolding(curwin))
-		{
-		    // Count the number of logical lines between the cursor and
-		    // botline - scrolloff (approximation of how much will be
-		    // scrolled).
-		    line_count = 0;
-		    for (lnum = curwin->w_cursor.lnum;
-				   lnum >= curwin->w_botline - *so_ptr; --lnum)
-		    {
-			++line_count;
-			// stop at end of file or when we know we are far off
-			if (lnum <= 0 || line_count > curwin->w_height + 1)
-			    break;
-			(void)hasFolding(lnum, &lnum, NULL);
-		    }
-		}
-		else
-#endif
-		    line_count = curwin->w_cursor.lnum - curwin->w_botline
-								 + 1 + *so_ptr;
-		if (line_count <= curwin->w_height + 1)
-		    scroll_cursor_bot(scrolljump_value(), FALSE);
-		else
-		    scroll_cursor_halfway(FALSE, FALSE);
-	    }
-	}
-    }
-    curwin->w_valid |= VALID_TOPLINE;
-
-    /*
-     * Need to redraw when topline changed.
-     */
-    if (curwin->w_topline != old_topline
-#ifdef FEAT_DIFF
-	    || curwin->w_topfill != old_topfill
-#endif
-	    )
-    {
-	dollar_vcol = -1;
-	redraw_later(UPD_VALID);
-
-	// When 'smoothscroll' is not set, should reset w_skipcol.
-	if (!curwin->w_p_sms)
-	    reset_skipcol();
-	else if (curwin->w_skipcol != 0)
-	    redraw_later(UPD_SOME_VALID);
-
-	// May need to set w_skipcol when cursor in w_topline.
-	if (curwin->w_cursor.lnum == curwin->w_topline)
-	    validate_cursor();
-    }
-
-    *so_ptr = save_so;
-}
-
-/*
- * Return the scrolljump value to use for the current window.
- * When 'scrolljump' is positive use it as-is.
- * When 'scrolljump' is negative use it as a percentage of the window height.
- */
-    static int
-scrolljump_value(void)
-{
-    if (p_sj >= 0)
-	return (int)p_sj;
-    return (curwin->w_height * -p_sj) / 100;
-}
-
-/*
- * Return TRUE when there are not 'scrolloff' lines above the cursor for the
- * current window.
- */
-    static int
-check_top_offset(void)
-{
-    lineoff_T	loff;
-    int		n;
-    long	so = get_scrolloff_value();
-
-    if (curwin->w_cursor.lnum < curwin->w_topline + so
-#ifdef FEAT_FOLDING
-		    || hasAnyFolding(curwin)
-#endif
-	    )
-    {
-	loff.lnum = curwin->w_cursor.lnum;
-#ifdef FEAT_DIFF
-	loff.fill = 0;
-	n = curwin->w_topfill;	    // always have this context
-#else
-	n = 0;
-#endif
-	// Count the visible screen lines above the cursor line.
-	while (n < so)
-	{
-	    topline_back(&loff);
-	    // Stop when included a line above the window.
-	    if (loff.lnum < curwin->w_topline
-#ifdef FEAT_DIFF
-		    || (loff.lnum == curwin->w_topline && loff.fill > 0)
-#endif
-		    )
-		break;
-	    n += loff.height;
-	}
-	if (n < so)
-	    return TRUE;
-    }
-    return FALSE;
-}
-
-/*
- * Update w_curswant.
- */
-    void
-update_curswant_force(void)
-{
-    validate_virtcol();
-    curwin->w_curswant = curwin->w_virtcol
-#ifdef FEAT_PROP_POPUP
-	- curwin->w_virtcol_first_char
-#endif
-	;
-    curwin->w_set_curswant = FALSE;
-}
-
-/*
- * Update w_curswant if w_set_curswant is set.
- */
-    void
-update_curswant(void)
-{
-    if (curwin->w_set_curswant)
-	update_curswant_force();
-}
-
-/*
- * Check if the cursor has moved.  Set the w_valid flag accordingly.
- */
-    void
-check_cursor_moved(win_T *wp)
-{
-    if (wp->w_cursor.lnum != wp->w_valid_cursor.lnum)
-    {
-	wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
-				      |VALID_CHEIGHT|VALID_CROW|VALID_TOPLINE
-				      |VALID_BOTLINE|VALID_BOTLINE_AP);
-	wp->w_valid_cursor = wp->w_cursor;
-	wp->w_valid_leftcol = wp->w_leftcol;
-	wp->w_valid_skipcol = wp->w_skipcol;
-    }
-    else if (wp->w_skipcol != wp->w_valid_skipcol)
-    {
-	wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
-				      |VALID_CHEIGHT|VALID_CROW
-				      |VALID_BOTLINE|VALID_BOTLINE_AP);
-	wp->w_valid_cursor = wp->w_cursor;
-	wp->w_valid_leftcol = wp->w_leftcol;
-	wp->w_valid_skipcol = wp->w_skipcol;
-    }
-    else if (wp->w_cursor.col != wp->w_valid_cursor.col
-	     || wp->w_leftcol != wp->w_valid_leftcol
-	     || wp->w_cursor.coladd != wp->w_valid_cursor.coladd)
-    {
-	wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL);
-	wp->w_valid_cursor.col = wp->w_cursor.col;
-	wp->w_valid_leftcol = wp->w_leftcol;
-	wp->w_valid_cursor.coladd = wp->w_cursor.coladd;
-    }
-}
-
-/*
- * Call this function when some window settings have changed, which require
- * the cursor position, botline and topline to be recomputed and the window to
- * be redrawn.  E.g, when changing the 'wrap' option or folding.
- */
-    void
-changed_window_setting(void)
-{
-    changed_window_setting_win(curwin);
-}
-
-    void
-changed_window_setting_win(win_T *wp)
-{
-    wp->w_lines_valid = 0;
-    changed_line_abv_curs_win(wp);
-    wp->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP|VALID_TOPLINE);
-    redraw_win_later(wp, UPD_NOT_VALID);
-}
-
-#if defined(FEAT_PROP_POPUP) || defined(PROTO)
-/*
- * Call changed_window_setting_win() for every window containing "buf".
- */
-    void
-changed_window_setting_buf(buf_T *buf)
-{
-    tabpage_T	*tp;
-    win_T	*wp;
-
-    FOR_ALL_TAB_WINDOWS(tp, wp)
-	if (wp->w_buffer == buf)
-	    changed_window_setting_win(wp);
-}
-#endif
-
-/*
- * Set wp->w_topline to a certain number.
- */
-    void
-set_topline(win_T *wp, linenr_T lnum)
-{
-#ifdef FEAT_DIFF
-    linenr_T prev_topline = wp->w_topline;
-#endif
-
-#ifdef FEAT_FOLDING
-    // go to first of folded lines
-    (void)hasFoldingWin(wp, lnum, &lnum, NULL, TRUE, NULL);
-#endif
-    // Approximate the value of w_botline
-    wp->w_botline += lnum - wp->w_topline;
-    if (wp->w_botline > wp->w_buffer->b_ml.ml_line_count + 1)
-	wp->w_botline = wp->w_buffer->b_ml.ml_line_count + 1;
-    wp->w_topline = lnum;
-    wp->w_topline_was_set = TRUE;
-#ifdef FEAT_DIFF
-    if (lnum != prev_topline)
-	// Keep the filler lines when the topline didn't change.
-	wp->w_topfill = 0;
-#endif
-    wp->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_TOPLINE);
-    // Don't set VALID_TOPLINE here, 'scrolloff' needs to be checked.
-    redraw_later(UPD_VALID);
-}
-
-/*
- * Call this function when the length of the cursor line (in screen
- * characters) has changed, and the change is before the cursor.
- * If the line length changed the number of screen lines might change,
- * requiring updating w_topline.  That may also invalidate w_crow.
- * Need to take care of w_botline separately!
- */
-    void
-changed_cline_bef_curs(void)
-{
-    curwin->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
-						|VALID_CHEIGHT|VALID_TOPLINE);
-}
-
-    void
-changed_cline_bef_curs_win(win_T *wp)
-{
-    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
-						|VALID_CHEIGHT|VALID_TOPLINE);
-}
-
-/*
- * Call this function when the length of a line (in screen characters) above
- * the cursor have changed.
- * Need to take care of w_botline separately!
- */
-    void
-changed_line_abv_curs(void)
-{
-    curwin->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
-						|VALID_CHEIGHT|VALID_TOPLINE);
-}
-
-    void
-changed_line_abv_curs_win(win_T *wp)
-{
-    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
-						|VALID_CHEIGHT|VALID_TOPLINE);
-}
-
-#if defined(FEAT_PROP_POPUP) || defined(PROTO)
-/*
- * Display of line has changed for "buf", invalidate cursor position and
- * w_botline.
- */
-    void
-changed_line_display_buf(buf_T *buf)
-{
-    win_T *wp;
-
-    FOR_ALL_WINDOWS(wp)
-	if (wp->w_buffer == buf)
-	    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
-				|VALID_CROW|VALID_CHEIGHT
-				|VALID_TOPLINE|VALID_BOTLINE|VALID_BOTLINE_AP);
-}
-#endif
-
-/*
- * Make sure the value of curwin->w_botline is valid.
- */
-    void
-validate_botline(void)
-{
-    validate_botline_win(curwin);
-}
-
-/*
- * Make sure the value of wp->w_botline is valid.
- */
-    void
-validate_botline_win(win_T *wp)
-{
-    if (!(wp->w_valid & VALID_BOTLINE))
-	comp_botline(wp);
-}
-
-/*
- * Mark curwin->w_botline as invalid (because of some change in the buffer).
- */
-    void
-invalidate_botline(void)
-{
-    curwin->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
-}
-
-    void
-invalidate_botline_win(win_T *wp)
-{
-    wp->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
-}
-
-    void
-approximate_botline_win(
-    win_T	*wp)
-{
-    wp->w_valid &= ~VALID_BOTLINE;
-}
-
-/*
- * Return TRUE if curwin->w_wrow and curwin->w_wcol are valid.
- */
-    int
-cursor_valid(void)
-{
-    check_cursor_moved(curwin);
-    return ((curwin->w_valid & (VALID_WROW|VALID_WCOL)) ==
-						      (VALID_WROW|VALID_WCOL));
-}
-
-/*
- * Validate cursor position.  Makes sure w_wrow and w_wcol are valid.
- * w_topline must be valid, you may need to call update_topline() first!
- */
-    void
-validate_cursor(void)
-{
-    check_cursor_lnum();
-    check_cursor_moved(curwin);
-    if ((curwin->w_valid & (VALID_WCOL|VALID_WROW)) != (VALID_WCOL|VALID_WROW))
-	curs_columns(TRUE);
-}
-
-#if defined(FEAT_GUI) || defined(PROTO)
-/*
- * validate w_cline_row.
- */
-    void
-validate_cline_row(void)
-{
-    /*
-     * First make sure that w_topline is valid (after moving the cursor).
-     */
-    update_topline();
-    check_cursor_moved(curwin);
-    if (!(curwin->w_valid & VALID_CROW))
-	curs_rows(curwin);
-}
-#endif
-
-/*
- * Compute wp->w_cline_row and wp->w_cline_height, based on the current value
- * of wp->w_topline.
- */
-    static void
-curs_rows(win_T *wp)
-{
-    linenr_T	lnum;
-    int		i;
-    int		all_invalid;
-    int		valid;
-#ifdef FEAT_FOLDING
-    long	fold_count;
-#endif
-
-    // Check if wp->w_lines[].wl_size is invalid
-    all_invalid = (!redrawing()
-			|| wp->w_lines_valid == 0
-			|| wp->w_lines[0].wl_lnum > wp->w_topline);
-    i = 0;
-    wp->w_cline_row = 0;
-    for (lnum = wp->w_topline; lnum < wp->w_cursor.lnum; ++i)
-    {
-	valid = FALSE;
-	if (!all_invalid && i < wp->w_lines_valid)
-	{
-	    if (wp->w_lines[i].wl_lnum < lnum || !wp->w_lines[i].wl_valid)
-		continue;		// skip changed or deleted lines
-	    if (wp->w_lines[i].wl_lnum == lnum)
-	    {
-#ifdef FEAT_FOLDING
-		// Check for newly inserted lines below this row, in which
-		// case we need to check for folded lines.
-		if (!wp->w_buffer->b_mod_set
-			|| wp->w_lines[i].wl_lastlnum < wp->w_cursor.lnum
-			|| wp->w_buffer->b_mod_top
-					     > wp->w_lines[i].wl_lastlnum + 1)
-#endif
-		valid = TRUE;
-	    }
-	    else if (wp->w_lines[i].wl_lnum > lnum)
-		--i;			// hold at inserted lines
-	}
-	if (valid
-	       && (lnum != wp->w_topline || (wp->w_skipcol == 0
-#ifdef FEAT_DIFF
-					    && !wp->w_p_diff
-#endif
-	       )))
-	{
-#ifdef FEAT_FOLDING
-	    lnum = wp->w_lines[i].wl_lastlnum + 1;
-	    // Cursor inside folded lines, don't count this row
-	    if (lnum > wp->w_cursor.lnum)
-		break;
-#else
-	    ++lnum;
-#endif
-	    wp->w_cline_row += wp->w_lines[i].wl_size;
-	}
-	else
-	{
-#ifdef FEAT_FOLDING
-	    fold_count = foldedCount(wp, lnum, NULL);
-	    if (fold_count)
-	    {
-		lnum += fold_count;
-		if (lnum > wp->w_cursor.lnum)
-		    break;
-		++wp->w_cline_row;
-	    }
-	    else
-#endif
-	    {
-		wp->w_cline_row += plines_correct_topline(wp, lnum);
-		++lnum;
-	    }
-	}
-    }
-
-    check_cursor_moved(wp);
-    if (!(wp->w_valid & VALID_CHEIGHT))
-    {
-	if (all_invalid
-		|| i == wp->w_lines_valid
-		|| (i < wp->w_lines_valid
-		    && (!wp->w_lines[i].wl_valid
-			|| wp->w_lines[i].wl_lnum != wp->w_cursor.lnum)))
-	{
-#ifdef FEAT_DIFF
-	    if (wp->w_cursor.lnum == wp->w_topline)
-		wp->w_cline_height = plines_win_nofill(wp, wp->w_cursor.lnum,
-							TRUE) + wp->w_topfill;
-	    else
-#endif
-		wp->w_cline_height = plines_win(wp, wp->w_cursor.lnum, TRUE);
-#ifdef FEAT_FOLDING
-	    wp->w_cline_folded = hasFoldingWin(wp, wp->w_cursor.lnum,
-						      NULL, NULL, TRUE, NULL);
-#endif
-	}
-	else if (i > wp->w_lines_valid)
-	{
-	    // a line that is too long to fit on the last screen line
-	    wp->w_cline_height = 0;
-#ifdef FEAT_FOLDING
-	    wp->w_cline_folded = hasFoldingWin(wp, wp->w_cursor.lnum,
-						      NULL, NULL, TRUE, NULL);
-#endif
-	}
-	else
-	{
-	    wp->w_cline_height = wp->w_lines[i].wl_size;
-#ifdef FEAT_FOLDING
-	    wp->w_cline_folded = wp->w_lines[i].wl_folded;
-#endif
-	}
-    }
-
-    redraw_for_cursorline(curwin);
-    wp->w_valid |= VALID_CROW|VALID_CHEIGHT;
-}
-
-/*
- * Validate curwin->w_virtcol only.
- */
-    void
-validate_virtcol(void)
-{
-    validate_virtcol_win(curwin);
-}
-
-/*
- * Validate wp->w_virtcol only.
- */
-    void
-validate_virtcol_win(win_T *wp)
-{
-    check_cursor_moved(wp);
-
-    if (wp->w_valid & VALID_VIRTCOL)
-	return;
-
-#ifdef FEAT_PROP_POPUP
-    wp->w_virtcol_first_char = 0;
-#endif
-    getvvcol(wp, &wp->w_cursor, NULL, &(wp->w_virtcol), NULL);
-#ifdef FEAT_SYN_HL
-    redraw_for_cursorcolumn(wp);
-#endif
-    wp->w_valid |= VALID_VIRTCOL;
-}
-
-/*
- * Validate curwin->w_cline_height only.
- */
-    void
-validate_cheight(void)
-{
-    check_cursor_moved(curwin);
-
-    if (curwin->w_valid & VALID_CHEIGHT)
-	return;
-
-#ifdef FEAT_DIFF
-    if (curwin->w_cursor.lnum == curwin->w_topline)
-	curwin->w_cline_height = plines_nofill(curwin->w_cursor.lnum)
-	    + curwin->w_topfill;
-    else
-#endif
-	curwin->w_cline_height = plines(curwin->w_cursor.lnum);
-#ifdef FEAT_FOLDING
-    curwin->w_cline_folded = hasFolding(curwin->w_cursor.lnum, NULL, NULL);
-#endif
-    curwin->w_valid |= VALID_CHEIGHT;
-}
-
-/*
- * Validate w_wcol and w_virtcol only.
- */
-    void
-validate_cursor_col(void)
-{
-    colnr_T off;
-    colnr_T col;
-    int     width;
-
-    validate_virtcol();
-
-    if (curwin->w_valid & VALID_WCOL)
-	return;
-
-    col = curwin->w_virtcol;
-    off = curwin_col_off();
-    col += off;
-    width = curwin->w_width - off + curwin_col_off2();
-
-    // long line wrapping, adjust curwin->w_wrow
-    if (curwin->w_p_wrap
-	    && col >= (colnr_T)curwin->w_width
-	    && width > 0)
-	// use same formula as what is used in curs_columns()
-	col -= ((col - curwin->w_width) / width + 1) * width;
-    if (col > (int)curwin->w_leftcol)
-	col -= curwin->w_leftcol;
-    else
-	col = 0;
-    curwin->w_wcol = col;
-
-    curwin->w_valid |= VALID_WCOL;
-#ifdef FEAT_PROP_POPUP
-    curwin->w_flags &= ~WFLAG_WCOL_OFF_ADDED;
-#endif
-}
-
-/*
- * Compute offset of a window, occupied by absolute or relative line number,
- * fold column and sign column (these don't move when scrolling horizontally).
- */
-    int
-win_col_off(win_T *wp)
-{
-    return (((wp->w_p_nu || wp->w_p_rnu) ? number_width(wp) + 1 : 0)
-	    + (cmdwin_type == 0 || wp != curwin ? 0 : 1)
-#ifdef FEAT_FOLDING
-	    + wp->w_p_fdc
-#endif
-#ifdef FEAT_SIGNS
-	    + (signcolumn_on(wp) ? 2 : 0)
-#endif
-	   );
-}
-
-    int
-curwin_col_off(void)
-{
-    return win_col_off(curwin);
-}
-
-/*
- * Return the difference in column offset for the second screen line of a
- * wrapped line.  It's positive if 'number' or 'relativenumber' is on and 'n'
- * is in 'cpoptions'.
- */
-    int
-win_col_off2(win_T *wp)
-{
-    if ((wp->w_p_nu || wp->w_p_rnu) && vim_strchr(p_cpo, CPO_NUMCOL) != NULL)
-	return number_width(wp) + 1;
-    return 0;
-}
-
-    int
-curwin_col_off2(void)
-{
-    return win_col_off2(curwin);
-}
-
-/*
- * Compute curwin->w_wcol and curwin->w_virtcol.
- * Also updates curwin->w_wrow and curwin->w_cline_row.
- * Also updates curwin->w_leftcol.
- */
-    void
-curs_columns(
-    int		may_scroll)	// when TRUE, may scroll horizontally
-{
-    int		diff;
-    int		extra;		// offset for first screen line
-    int		off_left, off_right;
-    int		n;
-    int		p_lines;
-    int		width1;		// text width for first screen line
-    int		width2 = 0;	// text width for second and later screen line
-    int		new_leftcol;
-    colnr_T	startcol;
-    colnr_T	endcol;
-    colnr_T	prev_skipcol;
-    long	so = get_scrolloff_value();
-    long	siso = get_sidescrolloff_value();
-    int		did_sub_skipcol = FALSE;
-
-    /*
-     * First make sure that w_topline is valid (after moving the cursor).
-     */
-    update_topline();
-
-    /*
-     * Next make sure that w_cline_row is valid.
-     */
-    if (!(curwin->w_valid & VALID_CROW))
-	curs_rows(curwin);
-
-#ifdef FEAT_PROP_POPUP
-    // will be set by getvvcol() but not reset
-    curwin->w_virtcol_first_char = 0;
-#endif
-
-    /*
-     * Compute the number of virtual columns.
-     */
-#ifdef FEAT_FOLDING
-    if (curwin->w_cline_folded)
-	// In a folded line the cursor is always in the first column
-	startcol = curwin->w_virtcol = endcol = curwin->w_leftcol;
-    else
-#endif
-	getvvcol(curwin, &curwin->w_cursor,
-				&startcol, &(curwin->w_virtcol), &endcol);
-
-    // remove '$' from change command when cursor moves onto it
-    if (startcol > dollar_vcol)
-	dollar_vcol = -1;
-
-    extra = curwin_col_off();
-    curwin->w_wcol = curwin->w_virtcol + extra;
-    endcol += extra;
-
-    /*
-     * Now compute w_wrow, counting screen lines from w_cline_row.
-     */
-    curwin->w_wrow = curwin->w_cline_row;
-
-    width1 = curwin->w_width - extra;
-    if (width1 <= 0)
-    {
-	// No room for text, put cursor in last char of window.
-	// If not wrapping, the last non-empty line.
-	curwin->w_wcol = curwin->w_width - 1;
-	if (curwin->w_p_wrap)
-	    curwin->w_wrow = curwin->w_height - 1;
-	else
-	    curwin->w_wrow = curwin->w_height - 1 - curwin->w_empty_rows;
-    }
-    else if (curwin->w_p_wrap && curwin->w_width != 0)
-    {
-	width2 = width1 + curwin_col_off2();
-
-	// skip columns that are not visible
-	if (curwin->w_cursor.lnum == curwin->w_topline
-		&& curwin->w_skipcol > 0
-		&& curwin->w_wcol >= curwin->w_skipcol)
-	{
-	    // Deduct by multiples of width2.  This allows the long line
-	    // wrapping formula below to correctly calculate the w_wcol value
-	    // when wrapping.
-	    if (curwin->w_skipcol <= width1)
-		curwin->w_wcol -= width2;
-	    else
-		curwin->w_wcol -= width2
-			       * (((curwin->w_skipcol - width1) / width2) + 1);
-
-	    did_sub_skipcol = TRUE;
-	}
-
-	// long line wrapping, adjust curwin->w_wrow
-	if (curwin->w_wcol >= curwin->w_width)
-	{
-	    // this same formula is used in validate_cursor_col()
-	    n = (curwin->w_wcol - curwin->w_width) / width2 + 1;
-	    curwin->w_wcol -= n * width2;
-	    curwin->w_wrow += n;
-
-#ifdef FEAT_LINEBREAK
-	    // When cursor wraps to first char of next line in Insert
-	    // mode, the 'showbreak' string isn't shown, backup to first
-	    // column
-	    char_u *sbr = get_showbreak_value(curwin);
-	    if (*sbr && *ml_get_cursor() == NUL
-				    && curwin->w_wcol == vim_strsize(sbr))
-		curwin->w_wcol = 0;
-#endif
-	}
-    }
-
-    // No line wrapping: compute curwin->w_leftcol if scrolling is on and line
-    // is not folded.
-    // If scrolling is off, curwin->w_leftcol is assumed to be 0
-    else if (may_scroll
-#ifdef FEAT_FOLDING
-	    && !curwin->w_cline_folded
-#endif
-	    )
-    {
-#ifdef FEAT_PROP_POPUP
-	if (curwin->w_virtcol_first_char > 0)
-	{
-	    int cols = (curwin->w_width - extra);
-	    int rows = cols > 0 ? curwin->w_virtcol_first_char / cols : 1;
-
-	    // each "above" text prop shifts the text one row down
-	    curwin->w_wrow += rows;
-	    curwin->w_wcol -= rows * cols;
-	    endcol -= rows * cols;
-	    curwin->w_cline_height = rows + 1;
-	}
-#endif
-	/*
-	 * If Cursor is left of the screen, scroll rightwards.
-	 * If Cursor is right of the screen, scroll leftwards
-	 * If we get closer to the edge than 'sidescrolloff', scroll a little
-	 * extra
-	 */
-	off_left = (int)startcol - (int)curwin->w_leftcol - siso;
-	off_right = (int)endcol - (int)(curwin->w_leftcol + curwin->w_width
-								- siso) + 1;
-	if (off_left < 0 || off_right > 0)
-	{
-	    if (off_left < 0)
-		diff = -off_left;
-	    else
-		diff = off_right;
-
-	    // When far off or not enough room on either side, put cursor in
-	    // middle of window.
-	    if (p_ss == 0 || diff >= width1 / 2 || off_right >= off_left)
-		new_leftcol = curwin->w_wcol - extra - width1 / 2;
-	    else
-	    {
-		if (diff < p_ss)
-		    diff = p_ss;
-		if (off_left < 0)
-		    new_leftcol = curwin->w_leftcol - diff;
-		else
-		    new_leftcol = curwin->w_leftcol + diff;
-	    }
-	    if (new_leftcol < 0)
-		new_leftcol = 0;
-	    if (new_leftcol != (int)curwin->w_leftcol)
-	    {
-		curwin->w_leftcol = new_leftcol;
-		// screen has to be redrawn with new curwin->w_leftcol
-		redraw_later(UPD_NOT_VALID);
-	    }
-	}
-	curwin->w_wcol -= curwin->w_leftcol;
-    }
-    else if (curwin->w_wcol > (int)curwin->w_leftcol)
-	curwin->w_wcol -= curwin->w_leftcol;
-    else
-	curwin->w_wcol = 0;
-
-#ifdef FEAT_DIFF
-    // Skip over filler lines.  At the top use w_topfill, there
-    // may be some filler lines above the window.
-    if (curwin->w_cursor.lnum == curwin->w_topline)
-	curwin->w_wrow += curwin->w_topfill;
-    else
-	curwin->w_wrow += diff_check_fill(curwin, curwin->w_cursor.lnum);
-#endif
-
-    prev_skipcol = curwin->w_skipcol;
-
-    p_lines = 0;
-
-    if ((curwin->w_wrow >= curwin->w_height
-		|| ((prev_skipcol > 0
-			|| curwin->w_wrow + so >= curwin->w_height)
-		    && (p_lines =
-#ifdef FEAT_DIFF
-			plines_win_nofill
-#else
-			plines_win
-#endif
-			(curwin, curwin->w_cursor.lnum, FALSE))
-						    - 1 >= curwin->w_height))
-	    && curwin->w_height != 0
-	    && curwin->w_cursor.lnum == curwin->w_topline
-	    && width2 > 0
-	    && curwin->w_width != 0)
-    {
-	// Cursor past end of screen.  Happens with a single line that does
-	// not fit on screen.  Find a skipcol to show the text around the
-	// cursor.  Avoid scrolling all the time. compute value of "extra":
-	// 1: Less than 'scrolloff' lines above
-	// 2: Less than 'scrolloff' lines below
-	// 3: both of them
-	extra = 0;
-	if (curwin->w_skipcol + so * width2 > curwin->w_virtcol)
-	    extra = 1;
-	// Compute last display line of the buffer line that we want at the
-	// bottom of the window.
-	if (p_lines == 0)
-	    p_lines = plines_win(curwin, curwin->w_cursor.lnum, FALSE);
-	--p_lines;
-	if (p_lines > curwin->w_wrow + so)
-	    n = curwin->w_wrow + so;
-	else
-	    n = p_lines;
-	if ((colnr_T)n >= curwin->w_height + curwin->w_skipcol / width2 - so)
-	    extra += 2;
-
-	if (extra == 3 || curwin->w_height <= so * 2)
-	{
-	    // not enough room for 'scrolloff', put cursor in the middle
-	    n = curwin->w_virtcol / width2;
-	    if (n > curwin->w_height / 2)
-		n -= curwin->w_height / 2;
-	    else
-		n = 0;
-	    // don't skip more than necessary
-	    if (n > p_lines - curwin->w_height + 1)
-		n = p_lines - curwin->w_height + 1;
-	    curwin->w_skipcol = n * width2;
-	}
-	else if (extra == 1)
-	{
-	    // less than 'scrolloff' lines above, decrease skipcol
-	    extra = (curwin->w_skipcol + so * width2 - curwin->w_virtcol
-				     + width2 - 1) / width2;
-	    if (extra > 0)
-	    {
-		if ((colnr_T)(extra * width2) > curwin->w_skipcol)
-		    extra = curwin->w_skipcol / width2;
-		curwin->w_skipcol -= extra * width2;
-	    }
-	}
-	else if (extra == 2)
-	{
-	    // less than 'scrolloff' lines below, increase skipcol
-	    endcol = (n - curwin->w_height + 1) * width2;
-	    while (endcol > curwin->w_virtcol)
-		endcol -= width2;
-	    if (endcol > curwin->w_skipcol)
-		curwin->w_skipcol = endcol;
-	}
-
-	// adjust w_wrow for the changed w_skipcol
-	if (did_sub_skipcol)
-	    curwin->w_wrow -= (curwin->w_skipcol - prev_skipcol) / width2;
-	else
-	    curwin->w_wrow -= curwin->w_skipcol / width2;
-
-	if (curwin->w_wrow >= curwin->w_height)
-	{
-	    // small window, make sure cursor is in it
-	    extra = curwin->w_wrow - curwin->w_height + 1;
-	    curwin->w_skipcol += extra * width2;
-	    curwin->w_wrow -= extra;
-	}
-
-	extra = ((int)prev_skipcol - (int)curwin->w_skipcol) / width2;
-	if (extra > 0)
-	    win_ins_lines(curwin, 0, extra, FALSE, FALSE);
-	else if (extra < 0)
-	    win_del_lines(curwin, 0, -extra, FALSE, FALSE, 0);
-    }
-    else if (!curwin->w_p_sms)
-	curwin->w_skipcol = 0;
-    if (prev_skipcol != curwin->w_skipcol)
-	redraw_later(UPD_SOME_VALID);
-
-#ifdef FEAT_SYN_HL
-    redraw_for_cursorcolumn(curwin);
-#endif
-#if defined(FEAT_PROP_POPUP) && defined(FEAT_TERMINAL)
-    if (popup_is_popup(curwin) && curbuf->b_term != NULL)
-    {
-	curwin->w_wrow += popup_top_extra(curwin);
-	curwin->w_wcol += popup_left_extra(curwin);
-	curwin->w_flags |= WFLAG_WCOL_OFF_ADDED + WFLAG_WROW_OFF_ADDED;
-    }
-    else
-	curwin->w_flags &= ~(WFLAG_WCOL_OFF_ADDED + WFLAG_WROW_OFF_ADDED);
-#endif
-
-    // now w_leftcol and w_skipcol are valid, avoid check_cursor_moved()
-    // thinking otherwise
-    curwin->w_valid_leftcol = curwin->w_leftcol;
-    curwin->w_valid_skipcol = curwin->w_skipcol;
-
-    curwin->w_valid |= VALID_WCOL|VALID_WROW|VALID_VIRTCOL;
-}
-
-#if (defined(FEAT_EVAL) || defined(FEAT_PROP_POPUP)) || defined(PROTO)
-/*
- * Compute the screen position of text character at "pos" in window "wp"
- * The resulting values are one-based, zero when character is not visible.
- */
-    void
-textpos2screenpos(
-	win_T	*wp,
-	pos_T	*pos,
-	int	*rowp,	// screen row
-	int	*scolp,	// start screen column
-	int	*ccolp,	// cursor screen column
-	int	*ecolp)	// end screen column
-{
-    colnr_T	scol = 0, ccol = 0, ecol = 0;
-    int		row = 0;
-    int		rowoff = 0;
-    colnr_T	coloff = 0;
-
-    if (pos->lnum >= wp->w_topline && pos->lnum <= wp->w_botline)
-    {
-	colnr_T	    col;
-	int	    width;
-	linenr_T    lnum = pos->lnum;
-#ifdef FEAT_FOLDING
-	int	    is_folded;
-
-	is_folded = hasFoldingWin(wp, lnum, &lnum, NULL, TRUE, NULL);
-#endif
-	row = plines_m_win(wp, wp->w_topline, lnum - 1) + 1;
-
-#ifdef FEAT_DIFF
-	// Add filler lines above this buffer line.
-	row += lnum == wp->w_topline ? wp->w_topfill
-				     : diff_check_fill(wp, lnum);
-#endif
-
-	colnr_T	off = win_col_off(wp);
-#ifdef FEAT_FOLDING
-	if (is_folded)
-	{
-	    row += W_WINROW(wp);
-	    coloff = wp->w_wincol + 1 + off;
-	}
-	else
-#endif
-	{
-	    getvcol(wp, pos, &scol, &ccol, &ecol);
-
-	    // similar to what is done in validate_cursor_col()
-	    col = scol;
-	    col += off;
-	    width = wp->w_width - off + win_col_off2(wp);
-
-	    if (lnum == wp->w_topline)
-		col -= wp->w_skipcol;
-
-	    // long line wrapping, adjust row
-	    if (wp->w_p_wrap
-		    && col >= (colnr_T)wp->w_width
-		    && width > 0)
-	    {
-		// use same formula as what is used in curs_columns()
-		rowoff = ((col - wp->w_width) / width + 1);
-		col -= rowoff * width;
-	    }
-	    col -= wp->w_leftcol;
-	    if (col >= wp->w_width)
-		col = -1;
-	    if (col >= 0 && row + rowoff <= wp->w_height)
-	    {
-		coloff = col - scol + wp->w_wincol + 1;
-		row += W_WINROW(wp);
-	    }
-	    else
-		// character is left, right or below of the window
-		row = rowoff = scol = ccol = ecol = 0;
-	}
-    }
-    *rowp = row + rowoff;
-    *scolp = scol + coloff;
-    *ccolp = ccol + coloff;
-    *ecolp = ecol + coloff;
-}
-#endif
-
-#if defined(FEAT_EVAL) || defined(PROTO)
-/*
- * "screenpos({winid}, {lnum}, {col})" function
- */
-    void
-f_screenpos(typval_T *argvars UNUSED, typval_T *rettv)
-{
-    dict_T	*dict;
-    win_T	*wp;
-    pos_T	pos;
-    int		row = 0;
-    int		scol = 0, ccol = 0, ecol = 0;
-
-    if (rettv_dict_alloc(rettv) == FAIL)
-	return;
-    dict = rettv->vval.v_dict;
-
-    if (in_vim9script()
-	    && (check_for_number_arg(argvars, 0) == FAIL
-		|| check_for_number_arg(argvars, 1) == FAIL
-		|| check_for_number_arg(argvars, 2) == FAIL))
-	return;
-
-    wp = find_win_by_nr_or_id(&argvars[0]);
-    if (wp == NULL)
-	return;
-
-    pos.lnum = tv_get_number(&argvars[1]);
-    if (pos.lnum > wp->w_buffer->b_ml.ml_line_count)
-    {
-	semsg(_(e_invalid_line_number_nr), pos.lnum);
-	return;
-    }
-    pos.col = tv_get_number(&argvars[2]) - 1;
-    pos.coladd = 0;
-    textpos2screenpos(wp, &pos, &row, &scol, &ccol, &ecol);
-
-    dict_add_number(dict, "row", row);
-    dict_add_number(dict, "col", scol);
-    dict_add_number(dict, "curscol", ccol);
-    dict_add_number(dict, "endcol", ecol);
-}
-
-/*
- * "virtcol2col({winid}, {lnum}, {col})" function
- */
-    void
-f_virtcol2col(typval_T *argvars UNUSED, typval_T *rettv)
-{
-    win_T	*wp;
-    linenr_T	lnum;
-    int		screencol;
-    int		error = FALSE;
-
-    rettv->vval.v_number = -1;
-
-    if (check_for_number_arg(argvars, 0) == FAIL
-	    || check_for_number_arg(argvars, 1) == FAIL
-	    || check_for_number_arg(argvars, 2) == FAIL)
-	return;
-
-    wp = find_win_by_nr_or_id(&argvars[0]);
-    if (wp == NULL)
-	return;
-
-    lnum = tv_get_number_chk(&argvars[1], &error);
-    if (error || lnum < 0 || lnum > wp->w_buffer->b_ml.ml_line_count)
-	return;
-
-    screencol = tv_get_number_chk(&argvars[2], &error);
-    if (error || screencol < 0)
-	return;
-
-    rettv->vval.v_number = vcol2col(wp, lnum, screencol);
-}
-#endif
-
-/*
- * Scroll the current window down by "line_count" logical lines.  "CTRL-Y"
- */
-    void
-scrolldown(
-    long	line_count,
-    int		byfold UNUSED)	// TRUE: count a closed fold as one line
-{
-    long	done = 0;	// total # of physical lines done
-    int		wrow;
-    int		moved = FALSE;
-    int		do_sms = curwin->w_p_wrap && curwin->w_p_sms;
-    int		width1 = 0;
-    int		width2 = 0;
-
-    if (do_sms)
-    {
-	width1 = curwin->w_width - curwin_col_off();
-	width2 = width1 + curwin_col_off2();
-    }
-
-#ifdef FEAT_FOLDING
-    linenr_T	first;
-
-    // Make sure w_topline is at the first of a sequence of folded lines.
-    (void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-    validate_cursor();		// w_wrow needs to be valid
-    for (int todo = line_count; todo > 0; --todo)
-    {
-#ifdef FEAT_DIFF
-	if (curwin->w_topfill < diff_check(curwin, curwin->w_topline)
-		&& curwin->w_topfill < curwin->w_height - 1)
-	{
-	    ++curwin->w_topfill;
-	    ++done;
-	}
-	else
-#endif
-	{
-	    // break when at the very top
-	    if (curwin->w_topline == 1
-				   && (!do_sms || curwin->w_skipcol < width1))
-		break;
-	    if (do_sms && curwin->w_skipcol >= width1)
-	    {
-		// scroll a screen line down
-		if (curwin->w_skipcol >= width1 + width2)
-		    curwin->w_skipcol -= width2;
-		else
-		    curwin->w_skipcol -= width1;
-		redraw_later(UPD_NOT_VALID);
-		++done;
-	    }
-	    else
-	    {
-		// scroll a text line down
-		--curwin->w_topline;
-		curwin->w_skipcol = 0;
-#ifdef FEAT_DIFF
-		curwin->w_topfill = 0;
-#endif
-#ifdef FEAT_FOLDING
-		// A sequence of folded lines only counts for one logical line
-		if (hasFolding(curwin->w_topline, &first, NULL))
-		{
-		    ++done;
-		    if (!byfold)
-			todo -= curwin->w_topline - first - 1;
-		    curwin->w_botline -= curwin->w_topline - first;
-		    curwin->w_topline = first;
-		}
-		else
-#endif
-		if (do_sms)
-		{
-		    int size = win_linetabsize(curwin, curwin->w_topline,
-				   ml_get(curwin->w_topline), (colnr_T)MAXCOL);
-		    if (size > width1)
-		    {
-			curwin->w_skipcol = width1;
-			size -= width1;
-			redraw_later(UPD_NOT_VALID);
-		    }
-		    while (size > width2)
-		    {
-			curwin->w_skipcol += width2;
-			size -= width2;
-		    }
-		    ++done;
-		}
-		else
-		    done += PLINES_NOFILL(curwin->w_topline);
-	    }
-	}
-	--curwin->w_botline;		// approximate w_botline
-	invalidate_botline();
-    }
-    curwin->w_wrow += done;		// keep w_wrow updated
-    curwin->w_cline_row += done;	// keep w_cline_row updated
-
-#ifdef FEAT_DIFF
-    if (curwin->w_cursor.lnum == curwin->w_topline)
-	curwin->w_cline_row = 0;
-    check_topfill(curwin, TRUE);
-#endif
-
-    /*
-     * Compute the row number of the last row of the cursor line
-     * and move the cursor onto the displayed part of the window.
-     */
-    wrow = curwin->w_wrow;
-    if (curwin->w_p_wrap && curwin->w_width != 0)
-    {
-	validate_virtcol();
-	validate_cheight();
-	wrow += curwin->w_cline_height - 1 -
-	    curwin->w_virtcol / curwin->w_width;
-    }
-    while (wrow >= curwin->w_height && curwin->w_cursor.lnum > 1)
-    {
-#ifdef FEAT_FOLDING
-	if (hasFolding(curwin->w_cursor.lnum, &first, NULL))
-	{
-	    --wrow;
-	    if (first == 1)
-		curwin->w_cursor.lnum = 1;
-	    else
-		curwin->w_cursor.lnum = first - 1;
-	}
-	else
-#endif
-	    wrow -= plines(curwin->w_cursor.lnum--);
-	curwin->w_valid &=
-	      ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW|VALID_VIRTCOL);
-	moved = TRUE;
-    }
-    if (moved)
-    {
-#ifdef FEAT_FOLDING
-	// Move cursor to first line of closed fold.
-	foldAdjustCursor();
-#endif
-	coladvance(curwin->w_curswant);
-    }
-
-    if (curwin->w_cursor.lnum == curwin->w_topline && do_sms)
-    {
-	long	so = get_scrolloff_value();
-	int	scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
-
-	// make sure the cursor is in the visible text
-	validate_virtcol();
-	int col = curwin->w_virtcol - curwin->w_skipcol + scrolloff_cols;
-	int row = 0;
-	if (col >= width1)
-	{
-	    col -= width1;
-	    ++row;
-	}
-	if (col > width2 && width2 > 0)
-	{
-	    row += col / width2;
-	    col = col % width2;
-	}
-	if (row >= curwin->w_height)
-	{
-	    curwin->w_curswant = curwin->w_virtcol
-				       - (row - curwin->w_height + 1) * width2;
-	    coladvance(curwin->w_curswant);
-	}
-    }
-}
-
-/*
- * Scroll the current window up by "line_count" logical lines.  "CTRL-E"
- */
-    void
-scrollup(
-    long	line_count,
-    int		byfold UNUSED)	// TRUE: count a closed fold as one line
-{
-    int		do_sms = curwin->w_p_wrap && curwin->w_p_sms;
-
-    if (do_sms
-# ifdef FEAT_FOLDING
-	    || (byfold && hasAnyFolding(curwin))
-# endif
-# ifdef FEAT_DIFF
-	    || (curwin->w_p_diff && !curwin->w_p_wrap)
-# endif
-       )
-    {
-	int	    width1 = curwin->w_width - curwin_col_off();
-	int	    width2 = width1 + curwin_col_off2();
-	int	    size = 0;
-	colnr_T	    prev_skipcol = curwin->w_skipcol;
-
-	if (do_sms)
-	    size = linetabsize(curwin, curwin->w_topline);
-
-	// diff mode: first consume "topfill"
-	// 'smoothscroll': increase "w_skipcol" until it goes over the end of
-	// the line, then advance to the next line.
-	// folding: count each sequence of folded lines as one logical line.
-	for (int todo = line_count; todo > 0; --todo)
-	{
-# ifdef FEAT_DIFF
-	    if (curwin->w_topfill > 0)
-		--curwin->w_topfill;
-	    else
-# endif
-	    {
-		linenr_T lnum = curwin->w_topline;
-
-# ifdef FEAT_FOLDING
-		if (byfold)
-		    // for a closed fold: go to the last line in the fold
-		    (void)hasFolding(lnum, NULL, &lnum);
-# endif
-		if (lnum == curwin->w_topline && do_sms)
-		{
-		    // 'smoothscroll': increase "w_skipcol" until it goes over
-		    // the end of the line, then advance to the next line.
-		    int add = curwin->w_skipcol > 0 ? width2 : width1;
-		    curwin->w_skipcol += add;
-		    if (curwin->w_skipcol >= size)
-		    {
-			if (lnum == curbuf->b_ml.ml_line_count)
-			{
-			    // at the last screen line, can't scroll further
-			    curwin->w_skipcol -= add;
-			    break;
-			}
-			++lnum;
-		    }
-		}
-		else
-		{
-		    if (lnum >= curbuf->b_ml.ml_line_count)
-			break;
-		    ++lnum;
-		}
-
-		if (lnum > curwin->w_topline)
-		{
-		    // approximate w_botline
-		    curwin->w_botline += lnum - curwin->w_topline;
-		    curwin->w_topline = lnum;
-# ifdef FEAT_DIFF
-		    curwin->w_topfill = diff_check_fill(curwin, lnum);
-# endif
-		    curwin->w_skipcol = 0;
-		    if (todo > 1 && do_sms)
-			size = linetabsize(curwin, curwin->w_topline);
-		}
-	    }
-	}
-
-	if (prev_skipcol > 0 || curwin->w_skipcol > 0)
-	    // need to redraw more, because wl_size of the (new) topline may
-	    // now be invalid
-	    redraw_later(UPD_NOT_VALID);
-    }
-    else
-    {
-	curwin->w_topline += line_count;
-	curwin->w_botline += line_count;	// approximate w_botline
-    }
-
-    if (curwin->w_topline > curbuf->b_ml.ml_line_count)
-	curwin->w_topline = curbuf->b_ml.ml_line_count;
-    if (curwin->w_botline > curbuf->b_ml.ml_line_count + 1)
-	curwin->w_botline = curbuf->b_ml.ml_line_count + 1;
-
-#ifdef FEAT_DIFF
-    check_topfill(curwin, FALSE);
-#endif
-
-#ifdef FEAT_FOLDING
-    if (hasAnyFolding(curwin))
-	// Make sure w_topline is at the first of a sequence of folded lines.
-	(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-
-    curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-    if (curwin->w_cursor.lnum < curwin->w_topline)
-    {
-	curwin->w_cursor.lnum = curwin->w_topline;
-	curwin->w_valid &=
-	      ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW|VALID_VIRTCOL);
-	coladvance(curwin->w_curswant);
-    }
-    if (curwin->w_cursor.lnum == curwin->w_topline
-					    && do_sms && curwin->w_skipcol > 0)
-    {
-	int	col_off = curwin_col_off();
-	int	col_off2 = curwin_col_off2();
-
-	int	width1 = curwin->w_width - col_off;
-	int	width2 = width1 + col_off2;
-	int	extra2 = col_off - col_off2;
-	long	so = get_scrolloff_value();
-	int	scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
-	int	space_cols = (curwin->w_height - 1) * width2;
-
-	// If we have non-zero scrolloff, just ignore the marker as we are
-	// going past it anyway.
-	int overlap = scrolloff_cols != 0 ? 0
-					  : sms_marker_overlap(curwin, extra2);
-
-	// Make sure the cursor is in a visible part of the line, taking
-	// 'scrolloff' into account, but using screen lines.
-	// If there are not enough screen lines put the cursor in the middle.
-	if (scrolloff_cols > space_cols / 2)
-	    scrolloff_cols = space_cols / 2;
-	validate_virtcol();
-	if (curwin->w_virtcol < curwin->w_skipcol + overlap + scrolloff_cols)
-	{
-	    colnr_T col = curwin->w_virtcol;
-
-	    if (col < width1)
-		col += width1;
-	    while (col < curwin->w_skipcol + overlap + scrolloff_cols)
-		col += width2;
-	    curwin->w_curswant = col;
-	    coladvance(curwin->w_curswant);
-
-	    // validate_virtcol() marked various things as valid, but after
-	    // moving the cursor they need to be recomputed
-	    curwin->w_valid &=
-	       ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW|VALID_VIRTCOL);
-	}
-    }
-}
-
-/*
- * Called after changing the cursor column: make sure that curwin->w_skipcol is
- * valid for 'smoothscroll'.
- */
-    void
-adjust_skipcol(void)
-{
-    if (!curwin->w_p_wrap
-	    || !curwin->w_p_sms
-	    || curwin->w_cursor.lnum != curwin->w_topline)
-	return;
-
-    int	    width1 = curwin->w_width - curwin_col_off();
-    if (width1 <= 0)
-	return;  // no text will be displayed
-
-    int	    width2 = width1 + curwin_col_off2();
-    long    so = get_scrolloff_value();
-    int	    scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
-    int	    scrolled = FALSE;
-
-    validate_cheight();
-    if (curwin->w_cline_height == curwin->w_height
-	    // w_cline_height may be capped at w_height, check there aren't
-	    // actually more lines.
-	    && plines_win(curwin, curwin->w_cursor.lnum, FALSE)
-							   <= curwin->w_height)
-    {
-	// the line just fits in the window, don't scroll
-	reset_skipcol();
-	return;
-    }
-
-    validate_virtcol();
-    int overlap = sms_marker_overlap(curwin,
-					 curwin_col_off() - curwin_col_off2());
-    while (curwin->w_skipcol > 0
-	    && curwin->w_virtcol < curwin->w_skipcol + overlap + scrolloff_cols)
-    {
-	// scroll a screen line down
-	if (curwin->w_skipcol >= width1 + width2)
-	    curwin->w_skipcol -= width2;
-	else
-	    curwin->w_skipcol -= width1;
-	scrolled = TRUE;
-    }
-    if (scrolled)
-    {
-	validate_virtcol();
-	redraw_later(UPD_NOT_VALID);
-	return;  // don't scroll in the other direction now
-    }
-
-    int col = curwin->w_virtcol - curwin->w_skipcol + scrolloff_cols;
-    int row = 0;
-    if (col >= width1)
-    {
-	col -= width1;
-	++row;
-    }
-    if (col > width2)
-    {
-	row += col / width2;
-	col = col % width2;
-    }
-    if (row >= curwin->w_height)
-    {
-	if (curwin->w_skipcol == 0)
-	{
-	    curwin->w_skipcol += width1;
-	    --row;
-	}
-	if (row >= curwin->w_height)
-	    curwin->w_skipcol += (row - curwin->w_height) * width2;
-	redraw_later(UPD_NOT_VALID);
-    }
-}
-
-#ifdef FEAT_DIFF
-/*
- * Don't end up with too many filler lines in the window.
- */
-    void
-check_topfill(
-    win_T	*wp,
-    int		down)	// when TRUE scroll down when not enough space
-{
-    int		n;
-
-    if (wp->w_topfill <= 0)
-	return;
-
-    n = plines_win_nofill(wp, wp->w_topline, TRUE);
-    if (wp->w_topfill + n > wp->w_height)
-    {
-	if (down && wp->w_topline > 1)
-	{
-	    --wp->w_topline;
-	    wp->w_topfill = 0;
-	}
-	else
-	{
-	    wp->w_topfill = wp->w_height - n;
-	    if (wp->w_topfill < 0)
-		wp->w_topfill = 0;
-	}
-    }
-}
-
-/*
- * Use as many filler lines as possible for w_topline.  Make sure w_topline
- * is still visible.
- */
-    static void
-max_topfill(void)
-{
-    int		n;
-
-    n = plines_nofill(curwin->w_topline);
-    if (n >= curwin->w_height)
-	curwin->w_topfill = 0;
-    else
-    {
-	curwin->w_topfill = diff_check_fill(curwin, curwin->w_topline);
-	if (curwin->w_topfill + n > curwin->w_height)
-	    curwin->w_topfill = curwin->w_height - n;
-    }
-}
-#endif
-
-/*
- * Scroll the screen one line down, but don't do it if it would move the
- * cursor off the screen.
- */
-    void
-scrolldown_clamp(void)
-{
-    int		end_row;
-#ifdef FEAT_DIFF
-    int		can_fill = (curwin->w_topfill
-				< diff_check_fill(curwin, curwin->w_topline));
-#endif
-
-    if (curwin->w_topline <= 1
-#ifdef FEAT_DIFF
-	    && !can_fill
-#endif
-	    )
-	return;
-
-    validate_cursor();	    // w_wrow needs to be valid
-
-    /*
-     * Compute the row number of the last row of the cursor line
-     * and make sure it doesn't go off the screen. Make sure the cursor
-     * doesn't go past 'scrolloff' lines from the screen end.
-     */
-    end_row = curwin->w_wrow;
-#ifdef FEAT_DIFF
-    if (can_fill)
-	++end_row;
-    else
-	end_row += plines_nofill(curwin->w_topline - 1);
-#else
-    end_row += plines(curwin->w_topline - 1);
-#endif
-    if (curwin->w_p_wrap && curwin->w_width != 0)
-    {
-	validate_cheight();
-	validate_virtcol();
-	end_row += curwin->w_cline_height - 1 -
-	    curwin->w_virtcol / curwin->w_width;
-    }
-    if (end_row < curwin->w_height - get_scrolloff_value())
-    {
-#ifdef FEAT_DIFF
-	if (can_fill)
-	{
-	    ++curwin->w_topfill;
-	    check_topfill(curwin, TRUE);
-	}
-	else
-	{
-	    --curwin->w_topline;
-	    curwin->w_topfill = 0;
-	}
-#else
-	--curwin->w_topline;
-#endif
-#ifdef FEAT_FOLDING
-	(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-	--curwin->w_botline;	    // approximate w_botline
-	curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-    }
-}
-
-/*
- * Scroll the screen one line up, but don't do it if it would move the cursor
- * off the screen.
- */
-    void
-scrollup_clamp(void)
-{
-    int	    start_row;
-
-    if (curwin->w_topline == curbuf->b_ml.ml_line_count
-#ifdef FEAT_DIFF
-	    && curwin->w_topfill == 0
-#endif
-	    )
-	return;
-
-    validate_cursor();	    // w_wrow needs to be valid
-
-    /*
-     * Compute the row number of the first row of the cursor line
-     * and make sure it doesn't go off the screen. Make sure the cursor
-     * doesn't go before 'scrolloff' lines from the screen start.
-     */
-#ifdef FEAT_DIFF
-    start_row = curwin->w_wrow - plines_nofill(curwin->w_topline)
-							  - curwin->w_topfill;
-#else
-    start_row = curwin->w_wrow - plines(curwin->w_topline);
-#endif
-    if (curwin->w_p_wrap && curwin->w_width != 0)
-    {
-	validate_virtcol();
-	start_row -= curwin->w_virtcol / curwin->w_width;
-    }
-    if (start_row >= get_scrolloff_value())
-    {
-#ifdef FEAT_DIFF
-	if (curwin->w_topfill > 0)
-	    --curwin->w_topfill;
-	else
-#endif
-	{
-#ifdef FEAT_FOLDING
-	    (void)hasFolding(curwin->w_topline, NULL, &curwin->w_topline);
-#endif
-	    ++curwin->w_topline;
-	}
-	++curwin->w_botline;		// approximate w_botline
-	curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-    }
-}
-
-/*
- * Add one line above "lp->lnum".  This can be a filler line, a closed fold or
- * a (wrapped) text line.  Uses and sets "lp->fill".
- * Returns the height of the added line in "lp->height".
- * Lines above the first one are incredibly high: MAXCOL.
- */
-    static void
-topline_back_winheight(
-    lineoff_T	*lp,
-    int		winheight)	// when TRUE limit to window height
-{
-#ifdef FEAT_DIFF
-    if (lp->fill < diff_check_fill(curwin, lp->lnum))
-    {
-	// Add a filler line.
-	++lp->fill;
-	lp->height = 1;
-    }
-    else
-#endif
-    {
-	--lp->lnum;
-#ifdef FEAT_DIFF
-	lp->fill = 0;
-#endif
-	if (lp->lnum < 1)
-	    lp->height = MAXCOL;
-	else
-#ifdef FEAT_FOLDING
-	    if (hasFolding(lp->lnum, &lp->lnum, NULL))
-	    // Add a closed fold
-	    lp->height = 1;
-	else
-#endif
-	    lp->height = PLINES_WIN_NOFILL(curwin, lp->lnum, winheight);
-    }
-}
-
-    static void
-topline_back(lineoff_T *lp)
-{
-    topline_back_winheight(lp, TRUE);
-}
-
-
-/*
- * Add one line below "lp->lnum".  This can be a filler line, a closed fold or
- * a (wrapped) text line.  Uses and sets "lp->fill".
- * Returns the height of the added line in "lp->height".
- * Lines below the last one are incredibly high.
- */
-    static void
-botline_forw(lineoff_T *lp)
-{
-#ifdef FEAT_DIFF
-    if (lp->fill < diff_check_fill(curwin, lp->lnum + 1))
-    {
-	// Add a filler line.
-	++lp->fill;
-	lp->height = 1;
-    }
-    else
-#endif
-    {
-	++lp->lnum;
-#ifdef FEAT_DIFF
-	lp->fill = 0;
-#endif
-	if (lp->lnum > curbuf->b_ml.ml_line_count)
-	    lp->height = MAXCOL;
-	else
-#ifdef FEAT_FOLDING
-	    if (hasFolding(lp->lnum, NULL, &lp->lnum))
-	    // Add a closed fold
-	    lp->height = 1;
-	else
-#endif
-	    lp->height = PLINES_NOFILL(lp->lnum);
-    }
-}
-
-#ifdef FEAT_DIFF
-/*
- * Switch from including filler lines below lp->lnum to including filler
- * lines above loff.lnum + 1.  This keeps pointing to the same line.
- * When there are no filler lines nothing changes.
- */
-    static void
-botline_topline(lineoff_T *lp)
-{
-    if (lp->fill > 0)
-    {
-	++lp->lnum;
-	lp->fill = diff_check_fill(curwin, lp->lnum) - lp->fill + 1;
-    }
-}
-
-/*
- * Switch from including filler lines above lp->lnum to including filler
- * lines below loff.lnum - 1.  This keeps pointing to the same line.
- * When there are no filler lines nothing changes.
- */
-    static void
-topline_botline(lineoff_T *lp)
-{
-    if (lp->fill > 0)
-    {
-	lp->fill = diff_check_fill(curwin, lp->lnum) - lp->fill + 1;
-	--lp->lnum;
-    }
-}
-#endif
-
-/*
- * Recompute topline to put the cursor at the top of the window.
- * Scroll at least "min_scroll" lines.
- * If "always" is TRUE, always set topline (for "zt").
- */
-    void
-scroll_cursor_top(int min_scroll, int always)
-{
-    int		scrolled = 0;
-    int		extra = 0;
-    int		used;
-    int		i;
-    linenr_T	top;		// just above displayed lines
-    linenr_T	bot;		// just below displayed lines
-    linenr_T	old_topline = curwin->w_topline;
-    int		old_skipcol = curwin->w_skipcol;
-#ifdef FEAT_DIFF
-    linenr_T	old_topfill = curwin->w_topfill;
-#endif
-    linenr_T	new_topline;
-    int		off = get_scrolloff_value();
-
-    if (mouse_dragging > 0)
-	off = mouse_dragging - 1;
-
-    /*
-     * Decrease topline until:
-     * - it has become 1
-     * - (part of) the cursor line is moved off the screen or
-     * - moved at least 'scrolljump' lines and
-     * - at least 'scrolloff' lines above and below the cursor
-     */
-    validate_cheight();
-    used = curwin->w_cline_height; // includes filler lines above
-    if (curwin->w_cursor.lnum < curwin->w_topline)
-	scrolled = used;
-
-#ifdef FEAT_FOLDING
-    if (hasFolding(curwin->w_cursor.lnum, &top, &bot))
-    {
-	--top;
-	++bot;
-    }
-    else
-#endif
-    {
-	top = curwin->w_cursor.lnum - 1;
-	bot = curwin->w_cursor.lnum + 1;
-    }
-    new_topline = top + 1;
-
-#ifdef FEAT_DIFF
-    // "used" already contains the number of filler lines above, don't add it
-    // again.
-    // Hide filler lines above cursor line by adding them to "extra".
-    extra += diff_check_fill(curwin, curwin->w_cursor.lnum);
-#endif
-
-    /*
-     * Check if the lines from "top" to "bot" fit in the window.  If they do,
-     * set new_topline and advance "top" and "bot" to include more lines.
-     */
-    while (top > 0)
-    {
-#ifdef FEAT_FOLDING
-	if (hasFolding(top, &top, NULL))
-	    // count one logical line for a sequence of folded lines
-	    i = 1;
-	else
-#endif
-	    i = PLINES_NOFILL(top);
-	if (top < curwin->w_topline)
-	    scrolled += i;
-
-	// If scrolling is needed, scroll at least 'sj' lines.
-	if ((new_topline >= curwin->w_topline || scrolled > min_scroll)
-		&& extra >= off)
-	    break;
-
-	used += i;
-	if (extra + i <= off && bot < curbuf->b_ml.ml_line_count)
-	{
-#ifdef FEAT_FOLDING
-	    if (hasFolding(bot, NULL, &bot))
-		// count one logical line for a sequence of folded lines
-		++used;
-	    else
-#endif
-		used += plines(bot);
-	}
-	if (used > curwin->w_height)
-	    break;
-
-	extra += i;
-	new_topline = top;
-	--top;
-	++bot;
-    }
-
-    /*
-     * If we don't have enough space, put cursor in the middle.
-     * This makes sure we get the same position when using "k" and "j"
-     * in a small window.
-     */
-    if (used > curwin->w_height)
-	scroll_cursor_halfway(FALSE, FALSE);
-    else
-    {
-	/*
-	 * If "always" is FALSE, only adjust topline to a lower value, higher
-	 * value may happen with wrapping lines.
-	 */
-	if (new_topline < curwin->w_topline || always)
-	    curwin->w_topline = new_topline;
-	if (curwin->w_topline > curwin->w_cursor.lnum)
-	    curwin->w_topline = curwin->w_cursor.lnum;
-#ifdef FEAT_DIFF
-	curwin->w_topfill = diff_check_fill(curwin, curwin->w_topline);
-	if (curwin->w_topfill > 0 && extra > off)
-	{
-	    curwin->w_topfill -= extra - off;
-	    if (curwin->w_topfill < 0)
-		curwin->w_topfill = 0;
-	}
-	check_topfill(curwin, FALSE);
-#endif
-	if (curwin->w_topline == curwin->w_cursor.lnum)
-	{
-	    validate_virtcol();
-	    if (curwin->w_skipcol >= curwin->w_virtcol)
-		// TODO: if the line doesn't fit may optimize w_skipcol instead
-		// of making it zero
-		reset_skipcol();
-	}
-	if (curwin->w_topline != old_topline
-		|| curwin->w_skipcol != old_skipcol
-#ifdef FEAT_DIFF
-		|| curwin->w_topfill != old_topfill
-#endif
-		)
-	    curwin->w_valid &=
-		      ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
-	curwin->w_valid |= VALID_TOPLINE;
-    }
-}
-
-/*
- * Set w_empty_rows and w_filler_rows for window "wp", having used up "used"
- * screen lines for text lines.
- */
-    void
-set_empty_rows(win_T *wp, int used)
-{
-#ifdef FEAT_DIFF
-    wp->w_filler_rows = 0;
-#endif
-    if (used == 0)
-	wp->w_empty_rows = 0;	// single line that doesn't fit
-    else
-    {
-	wp->w_empty_rows = wp->w_height - used;
-#ifdef FEAT_DIFF
-	if (wp->w_botline <= wp->w_buffer->b_ml.ml_line_count)
-	{
-	    wp->w_filler_rows = diff_check_fill(wp, wp->w_botline);
-	    if (wp->w_empty_rows > wp->w_filler_rows)
-		wp->w_empty_rows -= wp->w_filler_rows;
-	    else
-	    {
-		wp->w_filler_rows = wp->w_empty_rows;
-		wp->w_empty_rows = 0;
-	    }
-	}
-#endif
-    }
-}
-
-/*
- * Recompute topline to put the cursor at the bottom of the window.
- * When scrolling scroll at least "min_scroll" lines.
- * If "set_topbot" is TRUE, set topline and botline first (for "zb").
- * This is messy stuff!!!
- */
-    void
-scroll_cursor_bot(int min_scroll, int set_topbot)
-{
-    int		used;
-    int		scrolled = 0;
-    int		extra = 0;
-    int		i;
-    linenr_T	line_count;
-    linenr_T	old_topline = curwin->w_topline;
-    int		old_skipcol = curwin->w_skipcol;
-    lineoff_T	loff;
-    lineoff_T	boff;
-#ifdef FEAT_DIFF
-    int		old_topfill = curwin->w_topfill;
-    int		fill_below_window;
-#endif
-    linenr_T	old_botline = curwin->w_botline;
-    linenr_T	old_valid = curwin->w_valid;
-    int		old_empty_rows = curwin->w_empty_rows;
-    linenr_T	cln;		    // Cursor Line Number
-    long	so = get_scrolloff_value();
-    int		do_sms = curwin->w_p_wrap && curwin->w_p_sms;
-
-    cln = curwin->w_cursor.lnum;
-    if (set_topbot)
-    {
-	int set_skipcol = FALSE;
-
-	used = 0;
-	curwin->w_botline = cln + 1;
-#ifdef FEAT_DIFF
-	loff.fill = 0;
-#endif
-	for (curwin->w_topline = curwin->w_botline;
-		curwin->w_topline > 1;
-		curwin->w_topline = loff.lnum)
-	{
-	    loff.lnum = curwin->w_topline;
-	    topline_back_winheight(&loff, FALSE);
-	    if (loff.height == MAXCOL)
-		break;
-	    if (used + loff.height > curwin->w_height)
-	    {
-		if (do_sms)
-		{
-		    // 'smoothscroll' and 'wrap' are set.  The above line is
-		    // too long to show in its entirety, so we show just a part
-		    // of it.
-		    if (used < curwin->w_height)
-		    {
-			int plines_offset = used + loff.height
-							    - curwin->w_height;
-			used = curwin->w_height;
-#ifdef FEAT_DIFF
-			curwin->w_topfill = loff.fill;
-#endif
-			curwin->w_topline = loff.lnum;
-			curwin->w_skipcol = skipcol_from_plines(
-							curwin, plines_offset);
-			set_skipcol = TRUE;
-		    }
-		}
-		break;
-	    }
-	    used += loff.height;
-#ifdef FEAT_DIFF
-	    curwin->w_topfill = loff.fill;
-#endif
-	}
-	set_empty_rows(curwin, used);
-	curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
-	if (curwin->w_topline != old_topline
-#ifdef FEAT_DIFF
-		|| curwin->w_topfill != old_topfill
-#endif
-		|| set_skipcol
-		|| curwin->w_skipcol != 0)
-	{
-	    curwin->w_valid &= ~(VALID_WROW|VALID_CROW);
-	    if (set_skipcol)
-		redraw_later(UPD_NOT_VALID);
-	    else
-		reset_skipcol();
-	}
-    }
-    else
-	validate_botline();
-
-    // The lines of the cursor line itself are always used.
-#ifdef FEAT_DIFF
-    used = plines_nofill(cln);
-#else
-    validate_cheight();
-    used = curwin->w_cline_height;
-#endif
-
-    // If the cursor is on or below botline, we will at least scroll by the
-    // height of the cursor line, which is "used".  Correct for empty lines,
-    // which are really part of botline.
-    if (cln >= curwin->w_botline)
-    {
-	scrolled = used;
-	if (cln == curwin->w_botline)
-	    scrolled -= curwin->w_empty_rows;
-	if (do_sms)
-	{
-	    // 'smoothscroll' and 'wrap' are set.
-	    // Calculate how many screen lines the current top line of window
-	    // occupies. If it is occupying more than the entire window, we
-	    // need to scroll the additional clipped lines to scroll past the
-	    // top line before we can move on to the other lines.
-	    int top_plines =
-#ifdef FEAT_DIFF
-			    plines_win_nofill
-#else
-			    plines_win
-#endif
-					(curwin, curwin->w_topline, FALSE);
-	    int skip_lines = 0;
-	    int width1 = curwin->w_width - curwin_col_off();
-	    if (width1 > 0)
-	    {
-		int width2 = width1 + curwin_col_off2();
-		// similar formula is used in curs_columns()
-		if (curwin->w_skipcol > width1)
-		    skip_lines += (curwin->w_skipcol - width1) / width2 + 1;
-		else if (curwin->w_skipcol > 0)
-		    skip_lines = 1;
-
-		top_plines -= skip_lines;
-		if (top_plines > curwin->w_height)
-		{
-		    scrolled += (top_plines - curwin->w_height);
-		}
-	    }
-	}
-    }
-
-    /*
-     * Stop counting lines to scroll when
-     * - hitting start of the file
-     * - scrolled nothing or at least 'sj' lines
-     * - at least 'scrolloff' lines below the cursor
-     * - lines between botline and cursor have been counted
-     */
-#ifdef FEAT_FOLDING
-    if (!hasFolding(curwin->w_cursor.lnum, &loff.lnum, &boff.lnum))
-#endif
-    {
-	loff.lnum = cln;
-	boff.lnum = cln;
-    }
-#ifdef FEAT_DIFF
-    loff.fill = 0;
-    boff.fill = 0;
-    fill_below_window = diff_check_fill(curwin, curwin->w_botline)
-						      - curwin->w_filler_rows;
-#endif
-
-    while (loff.lnum > 1)
-    {
-	// Stop when scrolled nothing or at least "min_scroll", found "extra"
-	// context for 'scrolloff' and counted all lines below the window.
-	if ((((scrolled <= 0 || scrolled >= min_scroll)
-		    && extra >= (mouse_dragging > 0 ? mouse_dragging - 1 : so))
-		    || boff.lnum + 1 > curbuf->b_ml.ml_line_count)
-		&& loff.lnum <= curwin->w_botline
-#ifdef FEAT_DIFF
-		&& (loff.lnum < curwin->w_botline
-		    || loff.fill >= fill_below_window)
-#endif
-		)
-	    break;
-
-	// Add one line above
-	topline_back(&loff);
-	if (loff.height == MAXCOL)
-	    used = MAXCOL;
-	else
-	    used += loff.height;
-	if (used > curwin->w_height)
-	    break;
-	if (loff.lnum >= curwin->w_botline
-#ifdef FEAT_DIFF
-		&& (loff.lnum > curwin->w_botline
-		    || loff.fill <= fill_below_window)
-#endif
-		)
-	{
-	    // Count screen lines that are below the window.
-	    scrolled += loff.height;
-	    if (loff.lnum == curwin->w_botline
-#ifdef FEAT_DIFF
-			    && loff.fill == 0
-#endif
-		    )
-		scrolled -= curwin->w_empty_rows;
-	}
-
-	if (boff.lnum < curbuf->b_ml.ml_line_count)
-	{
-	    // Add one line below
-	    botline_forw(&boff);
-	    used += boff.height;
-	    if (used > curwin->w_height)
-		break;
-	    if (extra < ( mouse_dragging > 0 ? mouse_dragging - 1 : so)
-		    || scrolled < min_scroll)
-	    {
-		extra += boff.height;
-		if (boff.lnum >= curwin->w_botline
-#ifdef FEAT_DIFF
-			|| (boff.lnum + 1 == curwin->w_botline
-			    && boff.fill > curwin->w_filler_rows)
-#endif
-		   )
-		{
-		    // Count screen lines that are below the window.
-		    scrolled += boff.height;
-		    if (boff.lnum == curwin->w_botline
-#ifdef FEAT_DIFF
-			    && boff.fill == 0
-#endif
-			    )
-			scrolled -= curwin->w_empty_rows;
-		}
-	    }
-	}
-    }
-
-    // curwin->w_empty_rows is larger, no need to scroll
-    if (scrolled <= 0)
-	line_count = 0;
-    // more than a screenfull, don't scroll but redraw
-    else if (used > curwin->w_height)
-	line_count = used;
-    // scroll minimal number of lines
-    else
-    {
-	line_count = 0;
-#ifdef FEAT_DIFF
-	boff.fill = curwin->w_topfill;
-#endif
-	boff.lnum = curwin->w_topline - 1;
-	for (i = 0; i < scrolled && boff.lnum < curwin->w_botline; )
-	{
-	    botline_forw(&boff);
-	    i += boff.height;
-	    ++line_count;
-	}
-	if (i < scrolled)	// below curwin->w_botline, don't scroll
-	    line_count = 9999;
-    }
-
-    /*
-     * Scroll up if the cursor is off the bottom of the screen a bit.
-     * Otherwise put it at 1/2 of the screen.
-     */
-    if (line_count >= curwin->w_height && line_count > min_scroll)
-	scroll_cursor_halfway(FALSE, TRUE);
-    else if (line_count > 0)
-    {
-	if (do_sms)
-	    scrollup(scrolled, TRUE);  // TODO
-	else
-	    scrollup(line_count, TRUE);
-    }
-
-    /*
-     * If topline didn't change we need to restore w_botline and w_empty_rows
-     * (we changed them).
-     * If topline did change, update_screen() will set botline.
-     */
-    if (curwin->w_topline == old_topline
-	    && curwin->w_skipcol == old_skipcol
-	    && set_topbot)
-    {
-	curwin->w_botline = old_botline;
-	curwin->w_empty_rows = old_empty_rows;
-	curwin->w_valid = old_valid;
-    }
-    curwin->w_valid |= VALID_TOPLINE;
-}
-
-/*
- * Recompute topline to put the cursor halfway the window
- * If "atend" is TRUE, also put it halfway at the end of the file.
- */
-    void
-scroll_cursor_halfway(int atend, int prefer_above)
-{
-    int		above = 0;
-    linenr_T	topline;
-    colnr_T	skipcol = 0;
-#ifdef FEAT_DIFF
-    int		topfill = 0;
-#endif
-    int		below = 0;
-    int		used;
-    lineoff_T	loff;
-    lineoff_T	boff;
-#ifdef FEAT_DIFF
-    linenr_T	old_topline = curwin->w_topline;
-#endif
-
-#ifdef FEAT_PROP_POPUP
-    // if the width changed this needs to be updated first
-    may_update_popup_position();
-#endif
-    loff.lnum = boff.lnum = curwin->w_cursor.lnum;
-#ifdef FEAT_FOLDING
-    (void)hasFolding(loff.lnum, &loff.lnum, &boff.lnum);
-#endif
-#ifdef FEAT_DIFF
-    used = plines_nofill(loff.lnum);
-    loff.fill = 0;
-    boff.fill = 0;
-#else
-    used = plines(loff.lnum);
-#endif
-    topline = loff.lnum;
-
-    int want_height;
-    int do_sms = curwin->w_p_wrap && curwin->w_p_sms;
-    if (do_sms)
-    {
-	// 'smoothscroll' and 'wrap' are set
-	if (atend)
-	{
-	    want_height = (curwin->w_height - used) / 2;
-	    used = 0;
-	}
-	else
-	    want_height = curwin->w_height;
-    }
-
-    while (topline > 1)
-    {
-	// If using smoothscroll, we can precisely scroll to the
-	// exact point where the cursor is halfway down the screen.
-	if (do_sms)
-	{
-	    topline_back_winheight(&loff, FALSE);
-	    if (loff.height == MAXCOL)
-		break;
-	    used += loff.height;
-	    if (!atend && boff.lnum < curbuf->b_ml.ml_line_count)
-	    {
-		botline_forw(&boff);
-		used += boff.height;
-	    }
-	    if (used > want_height)
-	    {
-		if (used - loff.height < want_height)
-		{
-		    topline = loff.lnum;
-#ifdef FEAT_DIFF
-		    topfill = loff.fill;
-#endif
-		    skipcol = skipcol_from_plines(curwin, used - want_height);
-		}
-		break;
-	    }
-	    topline = loff.lnum;
-#ifdef FEAT_DIFF
-	    topfill = loff.fill;
-#endif
-	    continue;
-	}
-
-	// If not using smoothscroll, we have to iteratively find how many
-	// lines to scroll down to roughly fit the cursor.
-	// This may not be right in the middle if the lines'
-	// physical height > 1 (e.g. 'wrap' is on).
-
-	// Depending on "prefer_above" we add a line above or below first.
-	// Loop twice to avoid duplicating code.
-	int done = FALSE;
-	for (int round = 1; round <= 2; ++round)
-	{
-	    if (prefer_above ? (round == 2 && below < above)
-			     : (round == 1 && below <= above))
-	    {
-		// add a line below the cursor
-		if (boff.lnum < curbuf->b_ml.ml_line_count)
-		{
-		    botline_forw(&boff);
-		    used += boff.height;
-		    if (used > curwin->w_height)
-		    {
-			done = TRUE;
-			break;
-		    }
-		    below += boff.height;
-		}
-		else
-		{
-		    ++below;	    // count a "~" line
-		    if (atend)
-			++used;
-		}
-	    }
-
-	    if (prefer_above ? (round == 1 && below >= above)
-			     : (round == 1 && below > above))
-	    {
-		// add a line above the cursor
-		topline_back(&loff);
-		if (loff.height == MAXCOL)
-		    used = MAXCOL;
-		else
-		    used += loff.height;
-		if (used > curwin->w_height)
-		{
-		    done = TRUE;
-		    break;
-		}
-		above += loff.height;
-		topline = loff.lnum;
-#ifdef FEAT_DIFF
-		topfill = loff.fill;
-#endif
-	    }
-	}
-	if (done)
-	    break;
-    }
-
-#ifdef FEAT_FOLDING
-    if (!hasFolding(topline, &curwin->w_topline, NULL))
-#endif
-    {
-	if (curwin->w_topline != topline
-		|| skipcol != 0
-		|| curwin->w_skipcol != 0)
-	{
-	    curwin->w_topline = topline;
-	    if (skipcol != 0)
-	    {
-		curwin->w_skipcol = skipcol;
-		redraw_later(UPD_NOT_VALID);
-	    }
-	    else if (do_sms)
-		reset_skipcol();
-	}
-    }
-#ifdef FEAT_DIFF
-    curwin->w_topfill = topfill;
-    if (old_topline > curwin->w_topline + curwin->w_height)
-	curwin->w_botfill = FALSE;
-    check_topfill(curwin, FALSE);
-#endif
-    curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
-    curwin->w_valid |= VALID_TOPLINE;
-}
-
-/*
- * Correct the cursor position so that it is in a part of the screen at least
- * 'scrolloff' lines from the top and bottom, if possible.
- * If not possible, put it at the same position as scroll_cursor_halfway().
- * When called topline must be valid!
- */
-    void
-cursor_correct(void)
-{
-    int		above = 0;	    // screen lines above topline
-    linenr_T	topline;
-    int		below = 0;	    // screen lines below botline
-    linenr_T	botline;
-    int		above_wanted, below_wanted;
-    linenr_T	cln;		    // Cursor Line Number
-    int		max_off;
-    long	so = get_scrolloff_value();
-
-    /*
-     * How many lines we would like to have above/below the cursor depends on
-     * whether the first/last line of the file is on screen.
-     */
-    above_wanted = so;
-    below_wanted = so;
-    if (mouse_dragging > 0)
-    {
-	above_wanted = mouse_dragging - 1;
-	below_wanted = mouse_dragging - 1;
-    }
-    if (curwin->w_topline == 1)
-    {
-	above_wanted = 0;
-	max_off = curwin->w_height / 2;
-	if (below_wanted > max_off)
-	    below_wanted = max_off;
-    }
-    validate_botline();
-    if (curwin->w_botline == curbuf->b_ml.ml_line_count + 1
-	    && mouse_dragging == 0)
-    {
-	below_wanted = 0;
-	max_off = (curwin->w_height - 1) / 2;
-	if (above_wanted > max_off)
-	    above_wanted = max_off;
-    }
-
-    /*
-     * If there are sufficient file-lines above and below the cursor, we can
-     * return now.
-     */
-    cln = curwin->w_cursor.lnum;
-    if (cln >= curwin->w_topline + above_wanted
-	    && cln < curwin->w_botline - below_wanted
-#ifdef FEAT_FOLDING
-	    && !hasAnyFolding(curwin)
-#endif
-	    )
-	return;
-
-    if (curwin->w_p_sms && !curwin->w_p_wrap)
-    {
-	// 'smoothscroll' is active
-	if (curwin->w_cline_height == curwin->w_height)
-	{
-	    // The cursor line just fits in the window, don't scroll.
-	    reset_skipcol();
-	    return;
-	}
-	// TODO: If the cursor line doesn't fit in the window then only adjust
-	// w_skipcol.
-    }
-
-    /*
-     * Narrow down the area where the cursor can be put by taking lines from
-     * the top and the bottom until:
-     * - the desired context lines are found
-     * - the lines from the top is past the lines from the bottom
-     */
-    topline = curwin->w_topline;
-    botline = curwin->w_botline - 1;
-#ifdef FEAT_DIFF
-    // count filler lines as context
-    above = curwin->w_topfill;
-    below = curwin->w_filler_rows;
-#endif
-    while ((above < above_wanted || below < below_wanted) && topline < botline)
-    {
-	if (below < below_wanted && (below <= above || above >= above_wanted))
-	{
-#ifdef FEAT_FOLDING
-	    if (hasFolding(botline, &botline, NULL))
-		++below;
-	    else
-#endif
-		below += plines(botline);
-	    --botline;
-	}
-	if (above < above_wanted && (above < below || below >= below_wanted))
-	{
-#ifdef FEAT_FOLDING
-	    if (hasFolding(topline, NULL, &topline))
-		++above;
-	    else
-#endif
-		above += PLINES_NOFILL(topline);
-#ifdef FEAT_DIFF
-	    // Count filler lines below this line as context.
-	    if (topline < botline)
-		above += diff_check_fill(curwin, topline + 1);
-#endif
-	    ++topline;
-	}
-    }
-    if (topline == botline || botline == 0)
-	curwin->w_cursor.lnum = topline;
-    else if (topline > botline)
-	curwin->w_cursor.lnum = botline;
-    else
-    {
-	if (cln < topline && curwin->w_topline > 1)
-	{
-	    curwin->w_cursor.lnum = topline;
-	    curwin->w_valid &=
-			    ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW);
-	}
-	if (cln > botline && curwin->w_botline <= curbuf->b_ml.ml_line_count)
-	{
-	    curwin->w_cursor.lnum = botline;
-	    curwin->w_valid &=
-			    ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW);
-	}
-    }
-    curwin->w_valid |= VALID_TOPLINE;
-}
-
-static void get_scroll_overlap(lineoff_T *lp, int dir);
-
-/*
- * Move screen "count" pages up ("dir" is BACKWARD) or down ("dir" is FORWARD)
- * and update the screen.
- *
- * Return FAIL for failure, OK otherwise.
- */
-    int
-onepage(int dir, long count)
-{
-    long	n;
-    int		retval = OK;
-    lineoff_T	loff;
-    linenr_T	old_topline = curwin->w_topline;
-    long	so = get_scrolloff_value();
-
-    if (curbuf->b_ml.ml_line_count == 1)    // nothing to do
-    {
-	beep_flush();
-	return FAIL;
-    }
-
-    for ( ; count > 0; --count)
-    {
-	validate_botline();
-	/*
-	 * It's an error to move a page up when the first line is already on
-	 * the screen.	It's an error to move a page down when the last line
-	 * is on the screen and the topline is 'scrolloff' lines from the
-	 * last line.
-	 */
-	if (dir == FORWARD
-		? ((curwin->w_topline >= curbuf->b_ml.ml_line_count - so)
-		    && curwin->w_botline > curbuf->b_ml.ml_line_count)
-		: (curwin->w_topline == 1
-#ifdef FEAT_DIFF
-		    && curwin->w_topfill ==
-				    diff_check_fill(curwin, curwin->w_topline)
-#endif
-		    ))
-	{
-	    beep_flush();
-	    retval = FAIL;
-	    break;
-	}
-
-#ifdef FEAT_DIFF
-	loff.fill = 0;
-#endif
-	if (dir == FORWARD)
-	{
-	    if (ONE_WINDOW && p_window > 0 && p_window < Rows - 1)
-	    {
-		// Vi compatible scrolling
-		if (p_window <= 2)
-		    ++curwin->w_topline;
-		else
-		    curwin->w_topline += p_window - 2;
-		if (curwin->w_topline > curbuf->b_ml.ml_line_count)
-		    curwin->w_topline = curbuf->b_ml.ml_line_count;
-		curwin->w_cursor.lnum = curwin->w_topline;
-	    }
-	    else if (curwin->w_botline > curbuf->b_ml.ml_line_count)
-	    {
-		// at end of file
-		curwin->w_topline = curbuf->b_ml.ml_line_count;
-#ifdef FEAT_DIFF
-		curwin->w_topfill = 0;
-#endif
-		curwin->w_valid &= ~(VALID_WROW|VALID_CROW);
-	    }
-	    else
-	    {
-		// For the overlap, start with the line just below the window
-		// and go upwards.
-		loff.lnum = curwin->w_botline;
-#ifdef FEAT_DIFF
-		loff.fill = diff_check_fill(curwin, loff.lnum)
-						      - curwin->w_filler_rows;
-#endif
-		get_scroll_overlap(&loff, -1);
-		curwin->w_topline = loff.lnum;
-#ifdef FEAT_DIFF
-		curwin->w_topfill = loff.fill;
-		check_topfill(curwin, FALSE);
-#endif
-		curwin->w_cursor.lnum = curwin->w_topline;
-		curwin->w_valid &= ~(VALID_WCOL|VALID_CHEIGHT|VALID_WROW|
-				   VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
-	    }
-	}
-	else	// dir == BACKWARDS
-	{
-#ifdef FEAT_DIFF
-	    if (curwin->w_topline == 1)
-	    {
-		// Include max number of filler lines
-		max_topfill();
-		continue;
-	    }
-#endif
-	    if (ONE_WINDOW && p_window > 0 && p_window < Rows - 1)
-	    {
-		// Vi compatible scrolling (sort of)
-		if (p_window <= 2)
-		    --curwin->w_topline;
-		else
-		    curwin->w_topline -= p_window - 2;
-		if (curwin->w_topline < 1)
-		    curwin->w_topline = 1;
-		curwin->w_cursor.lnum = curwin->w_topline + p_window - 1;
-		if (curwin->w_cursor.lnum > curbuf->b_ml.ml_line_count)
-		    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
-		continue;
-	    }
-
-	    // Find the line at the top of the window that is going to be the
-	    // line at the bottom of the window.  Make sure this results in
-	    // the same line as before doing CTRL-F.
-	    loff.lnum = curwin->w_topline - 1;
-#ifdef FEAT_DIFF
-	    loff.fill = diff_check_fill(curwin, loff.lnum + 1)
-							  - curwin->w_topfill;
-#endif
-	    get_scroll_overlap(&loff, 1);
-
-	    if (loff.lnum >= curbuf->b_ml.ml_line_count)
-	    {
-		loff.lnum = curbuf->b_ml.ml_line_count;
-#ifdef FEAT_DIFF
-		loff.fill = 0;
-	    }
-	    else
-	    {
-		botline_topline(&loff);
-#endif
-	    }
-	    curwin->w_cursor.lnum = loff.lnum;
-
-	    // Find the line just above the new topline to get the right line
-	    // at the bottom of the window.
-	    n = 0;
-	    while (n <= curwin->w_height && loff.lnum >= 1)
-	    {
-		topline_back(&loff);
-		if (loff.height == MAXCOL)
-		    n = MAXCOL;
-		else
-		    n += loff.height;
-	    }
-	    if (loff.lnum < 1)			// at begin of file
-	    {
-		curwin->w_topline = 1;
-#ifdef FEAT_DIFF
-		max_topfill();
-#endif
-		curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-	    }
-	    else
-	    {
-		// Go two lines forward again.
-#ifdef FEAT_DIFF
-		topline_botline(&loff);
-#endif
-		botline_forw(&loff);
-		botline_forw(&loff);
-#ifdef FEAT_DIFF
-		botline_topline(&loff);
-#endif
-#ifdef FEAT_FOLDING
-		// We're at the wrong end of a fold now.
-		(void)hasFolding(loff.lnum, &loff.lnum, NULL);
-#endif
-
-		// Always scroll at least one line.  Avoid getting stuck on
-		// very long lines.
-		if (loff.lnum >= curwin->w_topline
-#ifdef FEAT_DIFF
-			&& (loff.lnum > curwin->w_topline
-			    || loff.fill >= curwin->w_topfill)
-#endif
-			)
-		{
-#ifdef FEAT_DIFF
-		    // First try using the maximum number of filler lines.  If
-		    // that's not enough, backup one line.
-		    loff.fill = curwin->w_topfill;
-		    if (curwin->w_topfill < diff_check_fill(curwin,
-							   curwin->w_topline))
-			max_topfill();
-		    if (curwin->w_topfill == loff.fill)
-#endif
-		    {
-			--curwin->w_topline;
-#ifdef FEAT_DIFF
-			curwin->w_topfill = 0;
-#endif
-		    }
-		    comp_botline(curwin);
-		    curwin->w_cursor.lnum = curwin->w_botline - 1;
-		    curwin->w_valid &=
-			    ~(VALID_WCOL|VALID_CHEIGHT|VALID_WROW|VALID_CROW);
-		}
-		else
-		{
-		    curwin->w_topline = loff.lnum;
-#ifdef FEAT_DIFF
-		    curwin->w_topfill = loff.fill;
-		    check_topfill(curwin, FALSE);
-#endif
-		    curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
-		}
-	    }
-	}
-    }
-#ifdef FEAT_FOLDING
-    foldAdjustCursor();
-#endif
-    cursor_correct();
-    check_cursor_col();
-    if (retval == OK)
-	beginline(BL_SOL | BL_FIX);
-    curwin->w_valid &= ~(VALID_WCOL|VALID_WROW|VALID_VIRTCOL);
-
-    if (retval == OK && dir == FORWARD)
-    {
-	// Avoid the screen jumping up and down when 'scrolloff' is non-zero.
-	// But make sure we scroll at least one line (happens with mix of long
-	// wrapping lines and non-wrapping line).
-	if (check_top_offset())
-	{
-	    scroll_cursor_top(1, FALSE);
-	    if (curwin->w_topline <= old_topline
-				  && old_topline < curbuf->b_ml.ml_line_count)
-	    {
-		curwin->w_topline = old_topline + 1;
-#ifdef FEAT_FOLDING
-		(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-	    }
-	}
-#ifdef FEAT_FOLDING
-	else if (curwin->w_botline > curbuf->b_ml.ml_line_count)
-	    (void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-    }
-
-    redraw_later(UPD_VALID);
-    return retval;
-}
-
-/*
- * Decide how much overlap to use for page-up or page-down scrolling.
- * This is symmetric, so that doing both keeps the same lines displayed.
- * Three lines are examined:
- *
- *  before CTRL-F	    after CTRL-F / before CTRL-B
- *     etc.			l1
- *  l1 last but one line	------------
- *  l2 last text line		l2 top text line
- *  -------------		l3 second text line
- *  l3				   etc.
- */
-    static void
-get_scroll_overlap(lineoff_T *lp, int dir)
-{
-    int		h1, h2, h3, h4;
-    int		min_height = curwin->w_height - 2;
-    lineoff_T	loff0, loff1, loff2;
-
-#ifdef FEAT_DIFF
-    if (lp->fill > 0)
-	lp->height = 1;
-    else
-	lp->height = plines_nofill(lp->lnum);
-#else
-    lp->height = plines(lp->lnum);
-#endif
-    h1 = lp->height;
-    if (h1 > min_height)
-	return;		// no overlap
-
-    loff0 = *lp;
-    if (dir > 0)
-	botline_forw(lp);
-    else
-	topline_back(lp);
-    h2 = lp->height;
-    if (h2 == MAXCOL || h2 + h1 > min_height)
-    {
-	*lp = loff0;	// no overlap
-	return;
-    }
-
-    loff1 = *lp;
-    if (dir > 0)
-	botline_forw(lp);
-    else
-	topline_back(lp);
-    h3 = lp->height;
-    if (h3 == MAXCOL || h3 + h2 > min_height)
-    {
-	*lp = loff0;	// no overlap
-	return;
-    }
-
-    loff2 = *lp;
-    if (dir > 0)
-	botline_forw(lp);
-    else
-	topline_back(lp);
-    h4 = lp->height;
-    if (h4 == MAXCOL || h4 + h3 + h2 > min_height || h3 + h2 + h1 > min_height)
-	*lp = loff1;	// 1 line overlap
-    else
-	*lp = loff2;	// 2 lines overlap
-}
-
-/*
- * Scroll 'scroll' lines up or down.
- */
-    void
-halfpage(int flag, linenr_T Prenum)
-{
-    long	scrolled = 0;
-    int		i;
-    int		n;
-    int		room;
-
-    if (Prenum)
-	curwin->w_p_scr = (Prenum > curwin->w_height) ?
-						curwin->w_height : Prenum;
-    n = (curwin->w_p_scr <= curwin->w_height) ?
-				    curwin->w_p_scr : curwin->w_height;
-
-    update_topline();
-    validate_botline();
-    room = curwin->w_empty_rows;
-#ifdef FEAT_DIFF
-    room += curwin->w_filler_rows;
-#endif
-    if (flag)
-    {
-	/*
-	 * scroll the text up
-	 */
-	while (n > 0 && curwin->w_botline <= curbuf->b_ml.ml_line_count)
-	{
-#ifdef FEAT_DIFF
-	    if (curwin->w_topfill > 0)
-	    {
-		i = 1;
-		--n;
-		--curwin->w_topfill;
-	    }
-	    else
-#endif
-	    {
-		i = PLINES_NOFILL(curwin->w_topline);
-		n -= i;
-		if (n < 0 && scrolled > 0)
-		    break;
-#ifdef FEAT_FOLDING
-		(void)hasFolding(curwin->w_topline, NULL, &curwin->w_topline);
-#endif
-		++curwin->w_topline;
-#ifdef FEAT_DIFF
-		curwin->w_topfill = diff_check_fill(curwin, curwin->w_topline);
-#endif
-
-		if (curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
-		{
-		    ++curwin->w_cursor.lnum;
-		    curwin->w_valid &=
-				    ~(VALID_VIRTCOL|VALID_CHEIGHT|VALID_WCOL);
-		}
-	    }
-	    curwin->w_valid &= ~(VALID_CROW|VALID_WROW);
-	    scrolled += i;
-
-	    /*
-	     * Correct w_botline for changed w_topline.
-	     * Won't work when there are filler lines.
-	     */
-#ifdef FEAT_DIFF
-	    if (curwin->w_p_diff)
-		curwin->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
-	    else
-#endif
-	    {
-		room += i;
-		do
-		{
-		    i = plines(curwin->w_botline);
-		    if (i > room)
-			break;
-#ifdef FEAT_FOLDING
-		    (void)hasFolding(curwin->w_botline, NULL,
-							  &curwin->w_botline);
-#endif
-		    ++curwin->w_botline;
-		    room -= i;
-		} while (curwin->w_botline <= curbuf->b_ml.ml_line_count);
-	    }
-	}
-
-	/*
-	 * When hit bottom of the file: move cursor down.
-	 */
-	if (n > 0)
-	{
-# ifdef FEAT_FOLDING
-	    if (hasAnyFolding(curwin))
-	    {
-		while (--n >= 0
-			&& curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
-		{
-		    (void)hasFolding(curwin->w_cursor.lnum, NULL,
-						      &curwin->w_cursor.lnum);
-		    ++curwin->w_cursor.lnum;
-		}
-	    }
-	    else
-# endif
-		curwin->w_cursor.lnum += n;
-	    check_cursor_lnum();
-	}
-    }
-    else
-    {
-	/*
-	 * scroll the text down
-	 */
-	while (n > 0 && curwin->w_topline > 1)
-	{
-#ifdef FEAT_DIFF
-	    if (curwin->w_topfill < diff_check_fill(curwin, curwin->w_topline))
-	    {
-		i = 1;
-		--n;
-		++curwin->w_topfill;
-	    }
-	    else
-#endif
-	    {
-		i = PLINES_NOFILL(curwin->w_topline - 1);
-		n -= i;
-		if (n < 0 && scrolled > 0)
-		    break;
-		--curwin->w_topline;
-#ifdef FEAT_FOLDING
-		(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
-#endif
-#ifdef FEAT_DIFF
-		curwin->w_topfill = 0;
-#endif
-	    }
-	    curwin->w_valid &= ~(VALID_CROW|VALID_WROW|
-					      VALID_BOTLINE|VALID_BOTLINE_AP);
-	    scrolled += i;
-	    if (curwin->w_cursor.lnum > 1)
-	    {
-		--curwin->w_cursor.lnum;
-		curwin->w_valid &= ~(VALID_VIRTCOL|VALID_CHEIGHT|VALID_WCOL);
-	    }
-	}
-
-	/*
-	 * When hit top of the file: move cursor up.
-	 */
-	if (n > 0)
-	{
-	    if (curwin->w_cursor.lnum <= (linenr_T)n)
-		curwin->w_cursor.lnum = 1;
-	    else
-# ifdef FEAT_FOLDING
-	    if (hasAnyFolding(curwin))
-	    {
-		while (--n >= 0 && curwin->w_cursor.lnum > 1)
-		{
-		    --curwin->w_cursor.lnum;
-		    (void)hasFolding(curwin->w_cursor.lnum,
-						&curwin->w_cursor.lnum, NULL);
-		}
-	    }
-	    else
-# endif
-		curwin->w_cursor.lnum -= n;
-	}
-    }
-# ifdef FEAT_FOLDING
-    // Move cursor to first line of closed fold.
-    foldAdjustCursor();
-# endif
-#ifdef FEAT_DIFF
-    check_topfill(curwin, !flag);
-#endif
-    cursor_correct();
-    beginline(BL_SOL | BL_FIX);
-    redraw_later(UPD_VALID);
-}
-
-    void
-do_check_cursorbind(void)
-{
-    linenr_T	line = curwin->w_cursor.lnum;
-    colnr_T	col = curwin->w_cursor.col;
-    colnr_T	coladd = curwin->w_cursor.coladd;
-    colnr_T	curswant = curwin->w_curswant;
-    int		set_curswant = curwin->w_set_curswant;
-    win_T	*old_curwin = curwin;
-    buf_T	*old_curbuf = curbuf;
-    int		old_VIsual_select = VIsual_select;
-    int		old_VIsual_active = VIsual_active;
-
-    /*
-     * loop through the cursorbound windows
-     */
-    VIsual_select = VIsual_active = 0;
-    FOR_ALL_WINDOWS(curwin)
-    {
-	curbuf = curwin->w_buffer;
-	// skip original window  and windows with 'noscrollbind'
-	if (curwin != old_curwin && curwin->w_p_crb)
-	{
-# ifdef FEAT_DIFF
-	    if (curwin->w_p_diff)
-		curwin->w_cursor.lnum =
-				 diff_get_corresponding_line(old_curbuf, line);
-	    else
-# endif
-		curwin->w_cursor.lnum = line;
-	    curwin->w_cursor.col = col;
-	    curwin->w_cursor.coladd = coladd;
-	    curwin->w_curswant = curswant;
-	    curwin->w_set_curswant = set_curswant;
-
-	    // Make sure the cursor is in a valid position.  Temporarily set
-	    // "restart_edit" to allow the cursor to be beyond the EOL.
-	    int restart_edit_save = restart_edit;
-	    restart_edit = 'a';
-	    check_cursor();
-
-	    // Avoid a scroll here for the cursor position, 'scrollbind' is
-	    // more important.
-	    if (!curwin->w_p_scb)
-		validate_cursor();
-
-	    restart_edit = restart_edit_save;
-	    // Correct cursor for multi-byte character.
-	    if (has_mbyte)
-		mb_adjust_cursor();
-	    redraw_later(UPD_VALID);
-
-	    // Only scroll when 'scrollbind' hasn't done this.
-	    if (!curwin->w_p_scb)
-		update_topline();
-	    curwin->w_redr_status = TRUE;
-	}
-    }
-
-    /*
-     * reset current-window
-     */
-    VIsual_select = old_VIsual_select;
-    VIsual_active = old_VIsual_active;
-    curwin = old_curwin;
-    curbuf = old_curbuf;
-}
+/* vi:set ts=8 sts=4 sw=4 noet:
+ *
+ * VIM - Vi IMproved	by Bram Moolenaar
+ *
+ * Do ":help uganda"  in Vim to read copying and usage conditions.
+ * Do ":help credits" in Vim to see a list of people who contributed.
+ * See README.txt for an overview of the Vim source code.
+ */
+/*
+ * move.c: Functions for moving the cursor and scrolling text.
+ *
+ * There are two ways to move the cursor:
+ * 1. Move the cursor directly, the text is scrolled to keep the cursor in the
+ *    window.
+ * 2. Scroll the text, the cursor is moved into the text visible in the
+ *    window.
+ * The 'scrolloff' option makes this a bit complicated.
+ */
+
+#include "vim.h"
+
+static int scrolljump_value(void);
+static int check_top_offset(void);
+static void curs_rows(win_T *wp);
+
+typedef struct
+{
+    linenr_T	    lnum;	// line number
+#ifdef FEAT_DIFF
+    int		    fill;	// filler lines
+#endif
+    int		    height;	// height of added line
+} lineoff_T;
+
+static void topline_back(lineoff_T *lp);
+static void botline_forw(lineoff_T *lp);
+
+/*
+ * Reduce "n" for the screen lines skipped with "wp->w_skipcol".
+ */
+    int
+adjust_plines_for_skipcol(win_T *wp, int n)
+{
+    if (wp->w_skipcol == 0)
+	return n;
+
+    int off = 0;
+    int width = wp->w_width - win_col_off(wp);
+    if (wp->w_skipcol >= width)
+    {
+	++off;
+	int skip = wp->w_skipcol - width;
+	width += win_col_off2(wp);
+	while (skip >= width)
+	{
+	    ++off;
+	    skip -= width;
+	}
+    }
+    wp->w_valid &= ~VALID_WROW;
+    return n - off;
+}
+
+/*
+ * Return how many lines "lnum" will take on the screen, taking into account
+ * whether it is the first line, whether w_skipcol is non-zero and limiting to
+ * the window height.
+ */
+    static int
+plines_correct_topline(win_T *wp, linenr_T lnum)
+{
+    int n;
+#ifdef FEAT_DIFF
+    if (lnum == wp->w_topline)
+	n = plines_win_nofill(wp, lnum, FALSE) + wp->w_topfill;
+    else
+#endif
+	n = plines_win(wp, lnum, FALSE);
+    if (lnum == wp->w_topline)
+	n = adjust_plines_for_skipcol(wp, n);
+    if (n > wp->w_height)
+	n = wp->w_height;
+    return n;
+}
+
+/*
+ * Compute wp->w_botline for the current wp->w_topline.  Can be called after
+ * wp->w_topline changed.
+ */
+    static void
+comp_botline(win_T *wp)
+{
+    int		n;
+    linenr_T	lnum;
+    int		done;
+#ifdef FEAT_FOLDING
+    linenr_T    last;
+    int		folded;
+#endif
+
+    /*
+     * If w_cline_row is valid, start there.
+     * Otherwise have to start at w_topline.
+     */
+    check_cursor_moved(wp);
+    if (wp->w_valid & VALID_CROW)
+    {
+	lnum = wp->w_cursor.lnum;
+	done = wp->w_cline_row;
+    }
+    else
+    {
+	lnum = wp->w_topline;
+	done = 0;
+    }
+
+    for ( ; lnum <= wp->w_buffer->b_ml.ml_line_count; ++lnum)
+    {
+#ifdef FEAT_FOLDING
+	last = lnum;
+	folded = FALSE;
+	if (hasFoldingWin(wp, lnum, NULL, &last, TRUE, NULL))
+	{
+	    n = 1;
+	    folded = TRUE;
+	}
+	else
+#endif
+	{
+	    n = plines_correct_topline(wp, lnum);
+	}
+	if (
+#ifdef FEAT_FOLDING
+		lnum <= wp->w_cursor.lnum && last >= wp->w_cursor.lnum
+#else
+		lnum == wp->w_cursor.lnum
+#endif
+	   )
+	{
+	    wp->w_cline_row = done;
+	    wp->w_cline_height = n;
+#ifdef FEAT_FOLDING
+	    wp->w_cline_folded = folded;
+#endif
+	    redraw_for_cursorline(wp);
+	    wp->w_valid |= (VALID_CROW|VALID_CHEIGHT);
+	}
+	if (done + n > wp->w_height)
+	    break;
+	done += n;
+#ifdef FEAT_FOLDING
+	lnum = last;
+#endif
+    }
+
+    // wp->w_botline is the line that is just below the window
+    wp->w_botline = lnum;
+    wp->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+
+    set_empty_rows(wp, done);
+}
+
+/*
+ * Redraw when w_cline_row changes and 'relativenumber' or 'cursorline' is
+ * set.
+ */
+    void
+redraw_for_cursorline(win_T *wp)
+{
+    if ((wp->w_p_rnu
+#ifdef FEAT_SYN_HL
+		|| wp->w_p_cul
+#endif
+		)
+	    && (wp->w_valid & VALID_CROW) == 0
+	    && !pum_visible())
+    {
+	// win_line() will redraw the number column and cursorline only.
+	redraw_win_later(wp, UPD_VALID);
+    }
+}
+
+#ifdef FEAT_SYN_HL
+/*
+ * Redraw when w_virtcol changes and 'cursorcolumn' is set or 'cursorlineopt'
+ * contains "screenline".
+ */
+    static void
+redraw_for_cursorcolumn(win_T *wp)
+{
+    if ((wp->w_valid & VALID_VIRTCOL) == 0 && !pum_visible())
+    {
+	// When 'cursorcolumn' is set need to redraw with UPD_SOME_VALID.
+	if (wp->w_p_cuc)
+	    redraw_win_later(wp, UPD_SOME_VALID);
+	// When 'cursorlineopt' contains "screenline" need to redraw with
+	// UPD_VALID.
+	else if (wp->w_p_cul && (wp->w_p_culopt_flags & CULOPT_SCRLINE))
+	    redraw_win_later(wp, UPD_VALID);
+    }
+}
+#endif
+
+/*
+ * Calculates how much the 'listchars' "precedes" or 'smoothscroll' "<<<"
+ * marker overlaps with buffer text for window "wp".
+ * Parameter "extra2" should be the padding on the 2nd line, not the first
+ * line.
+ * Returns the number of columns of overlap with buffer text, excluding the
+ * extra padding on the ledge.
+ */
+     int
+sms_marker_overlap(win_T *wp, int extra2)
+{
+#if defined(FEAT_LINEBREAK)
+    // There is no marker overlap when in showbreak mode, thus no need to
+    // account for it.  See wlv_screen_line().
+    if (*get_showbreak_value(wp) != NUL)
+	return 0;
+#endif
+    // Overlap when 'list' and 'listchars' "precedes" are set is 1.
+    if (wp->w_p_list && wp->w_lcs_chars.prec)
+	return 1;
+
+    return extra2 > 3 ? 0 : 3 - extra2;
+}
+
+/*
+ * Calculates the skipcol offset for window "wp" given how many
+ * physical lines we want to scroll down.
+ */
+    static int
+skipcol_from_plines(win_T *wp, int plines_off)
+{
+    int width1 = wp->w_width - win_col_off(wp);
+
+    int skipcol = 0;
+    if (plines_off > 0)
+	skipcol += width1;
+    if (plines_off > 1)
+	skipcol += (width1 + win_col_off2(wp)) * (plines_off - 1);
+    return skipcol;
+}
+
+/*
+ * Set curwin->w_skipcol to zero and redraw later if needed.
+ */
+    static void
+reset_skipcol(void)
+{
+    if (curwin->w_skipcol == 0)
+	return;
+
+    curwin->w_skipcol = 0;
+
+    // Should use the least expensive way that displays all that changed.
+    // UPD_NOT_VALID is too expensive, UPD_REDRAW_TOP does not redraw
+    // enough when the top line gets another screen line.
+    redraw_later(UPD_SOME_VALID);
+}
+
+/*
+ * Update curwin->w_topline and redraw if necessary.
+ * Used to update the screen before printing a message.
+ */
+    void
+update_topline_redraw(void)
+{
+    update_topline();
+    if (must_redraw)
+	update_screen(0);
+}
+
+/*
+ * Update curwin->w_topline to move the cursor onto the screen.
+ */
+    void
+update_topline(void)
+{
+    long	line_count;
+    int		halfheight;
+    int		n;
+#ifdef FEAT_FOLDING
+    linenr_T	lnum;
+#endif
+    int		check_topline = FALSE;
+    int		check_botline = FALSE;
+    long	*so_ptr = curwin->w_p_so >= 0 ? &curwin->w_p_so : &p_so;
+    int		save_so = *so_ptr;
+
+    // Cursor is updated instead when this is TRUE for 'splitkeep'.
+    if (skip_update_topline)
+	return;
+
+    // If there is no valid screen and when the window height is zero just use
+    // the cursor line.
+    if (!screen_valid(TRUE) || curwin->w_height == 0)
+    {
+	check_cursor_lnum();
+	curwin->w_topline = curwin->w_cursor.lnum;
+	curwin->w_botline = curwin->w_topline;
+	curwin->w_scbind_pos = 1;
+	return;
+    }
+
+    check_cursor_moved(curwin);
+    if (curwin->w_valid & VALID_TOPLINE)
+	return;
+
+    // When dragging with the mouse, don't scroll that quickly
+    if (mouse_dragging > 0)
+	*so_ptr = mouse_dragging - 1;
+
+    linenr_T old_topline = curwin->w_topline;
+#ifdef FEAT_DIFF
+    int old_topfill = curwin->w_topfill;
+#endif
+
+    /*
+     * If the buffer is empty, always set topline to 1.
+     */
+    if (BUFEMPTY())		// special case - file is empty
+    {
+	if (curwin->w_topline != 1)
+	    redraw_later(UPD_NOT_VALID);
+	curwin->w_topline = 1;
+	curwin->w_botline = 2;
+	curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+	curwin->w_scbind_pos = 1;
+    }
+
+    /*
+     * If the cursor is above or near the top of the window, scroll the window
+     * to show the line the cursor is in, with 'scrolloff' context.
+     */
+    else
+    {
+	if (curwin->w_topline > 1 || curwin->w_skipcol > 0)
+	{
+	    // If the cursor is above topline, scrolling is always needed.
+	    // If the cursor is far below topline and there is no folding,
+	    // scrolling down is never needed.
+	    if (curwin->w_cursor.lnum < curwin->w_topline)
+		check_topline = TRUE;
+	    else if (check_top_offset())
+		check_topline = TRUE;
+	    else if (curwin->w_skipcol > 0
+				 && curwin->w_cursor.lnum == curwin->w_topline)
+	    {
+		colnr_T vcol;
+
+		// Check that the cursor position is visible.  Add columns for
+		// the marker displayed in the top-left if needed.
+		getvvcol(curwin, &curwin->w_cursor, &vcol, NULL, NULL);
+		int overlap = sms_marker_overlap(curwin, curwin_col_off()
+							- curwin_col_off2());
+		if (curwin->w_skipcol + overlap > vcol)
+		    check_topline = TRUE;
+	    }
+	}
+#ifdef FEAT_DIFF
+	    // Check if there are more filler lines than allowed.
+	if (!check_topline && curwin->w_topfill > diff_check_fill(curwin,
+							   curwin->w_topline))
+	    check_topline = TRUE;
+#endif
+
+	if (check_topline)
+	{
+	    halfheight = curwin->w_height / 2 - 1;
+	    if (halfheight < 2)
+		halfheight = 2;
+
+#ifdef FEAT_FOLDING
+	    if (hasAnyFolding(curwin))
+	    {
+		// Count the number of logical lines between the cursor and
+		// topline + scrolloff (approximation of how much will be
+		// scrolled).
+		n = 0;
+		for (lnum = curwin->w_cursor.lnum;
+				    lnum < curwin->w_topline + *so_ptr; ++lnum)
+		{
+		    ++n;
+		    // stop at end of file or when we know we are far off
+		    if (lnum >= curbuf->b_ml.ml_line_count || n >= halfheight)
+			break;
+		    (void)hasFolding(lnum, NULL, &lnum);
+		}
+	    }
+	    else
+#endif
+		n = curwin->w_topline + *so_ptr - curwin->w_cursor.lnum;
+
+	    // If we weren't very close to begin with, we scroll to put the
+	    // cursor in the middle of the window.  Otherwise put the cursor
+	    // near the top of the window.
+	    if (n >= halfheight)
+		scroll_cursor_halfway(FALSE, FALSE);
+	    else
+	    {
+		scroll_cursor_top(scrolljump_value(), FALSE);
+		check_botline = TRUE;
+	    }
+	}
+
+	else
+	{
+#ifdef FEAT_FOLDING
+	    // Make sure topline is the first line of a fold.
+	    (void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+	    check_botline = TRUE;
+	}
+    }
+
+    /*
+     * If the cursor is below the bottom of the window, scroll the window
+     * to put the cursor on the window.
+     * When w_botline is invalid, recompute it first, to avoid a redraw later.
+     * If w_botline was approximated, we might need a redraw later in a few
+     * cases, but we don't want to spend (a lot of) time recomputing w_botline
+     * for every small change.
+     */
+    if (check_botline)
+    {
+	if (!(curwin->w_valid & VALID_BOTLINE_AP))
+	    validate_botline();
+
+	if (curwin->w_botline <= curbuf->b_ml.ml_line_count)
+	{
+	    if (curwin->w_cursor.lnum < curwin->w_botline)
+	    {
+	      if (((long)curwin->w_cursor.lnum
+					   >= (long)curwin->w_botline - *so_ptr
+#ifdef FEAT_FOLDING
+			|| hasAnyFolding(curwin)
+#endif
+			))
+	      {
+		lineoff_T	loff;
+
+		// Cursor is (a few lines) above botline, check if there are
+		// 'scrolloff' window lines below the cursor.  If not, need to
+		// scroll.
+		n = curwin->w_empty_rows;
+		loff.lnum = curwin->w_cursor.lnum;
+#ifdef FEAT_FOLDING
+		// In a fold go to its last line.
+		(void)hasFolding(loff.lnum, NULL, &loff.lnum);
+#endif
+#ifdef FEAT_DIFF
+		loff.fill = 0;
+		n += curwin->w_filler_rows;
+#endif
+		loff.height = 0;
+		while (loff.lnum < curwin->w_botline
+#ifdef FEAT_DIFF
+			&& (loff.lnum + 1 < curwin->w_botline || loff.fill == 0)
+#endif
+			)
+		{
+		    n += loff.height;
+		    if (n >= *so_ptr)
+			break;
+		    botline_forw(&loff);
+		}
+		if (n >= *so_ptr)
+		    // sufficient context, no need to scroll
+		    check_botline = FALSE;
+	      }
+	      else
+		  // sufficient context, no need to scroll
+		  check_botline = FALSE;
+	    }
+	    if (check_botline)
+	    {
+#ifdef FEAT_FOLDING
+		if (hasAnyFolding(curwin))
+		{
+		    // Count the number of logical lines between the cursor and
+		    // botline - scrolloff (approximation of how much will be
+		    // scrolled).
+		    line_count = 0;
+		    for (lnum = curwin->w_cursor.lnum;
+				   lnum >= curwin->w_botline - *so_ptr; --lnum)
+		    {
+			++line_count;
+			// stop at end of file or when we know we are far off
+			if (lnum <= 0 || line_count > curwin->w_height + 1)
+			    break;
+			(void)hasFolding(lnum, &lnum, NULL);
+		    }
+		}
+		else
+#endif
+		    line_count = curwin->w_cursor.lnum - curwin->w_botline
+								 + 1 + *so_ptr;
+		if (line_count <= curwin->w_height + 1)
+		    scroll_cursor_bot(scrolljump_value(), FALSE);
+		else
+		    scroll_cursor_halfway(FALSE, FALSE);
+	    }
+	}
+    }
+    curwin->w_valid |= VALID_TOPLINE;
+
+    /*
+     * Need to redraw when topline changed.
+     */
+    if (curwin->w_topline != old_topline
+#ifdef FEAT_DIFF
+	    || curwin->w_topfill != old_topfill
+#endif
+	    )
+    {
+	dollar_vcol = -1;
+	redraw_later(UPD_VALID);
+
+	// When 'smoothscroll' is not set, should reset w_skipcol.
+	if (!curwin->w_p_sms)
+	    reset_skipcol();
+	else if (curwin->w_skipcol != 0)
+	    redraw_later(UPD_SOME_VALID);
+
+	// May need to set w_skipcol when cursor in w_topline.
+	if (curwin->w_cursor.lnum == curwin->w_topline)
+	    validate_cursor();
+    }
+
+    *so_ptr = save_so;
+}
+
+/*
+ * Return the scrolljump value to use for the current window.
+ * When 'scrolljump' is positive use it as-is.
+ * When 'scrolljump' is negative use it as a percentage of the window height.
+ */
+    static int
+scrolljump_value(void)
+{
+    if (p_sj >= 0)
+	return (int)p_sj;
+    return (curwin->w_height * -p_sj) / 100;
+}
+
+/*
+ * Return TRUE when there are not 'scrolloff' lines above the cursor for the
+ * current window.
+ */
+    static int
+check_top_offset(void)
+{
+    lineoff_T	loff;
+    int		n;
+    long	so = get_scrolloff_value();
+
+    if (curwin->w_cursor.lnum < curwin->w_topline + so
+#ifdef FEAT_FOLDING
+		    || hasAnyFolding(curwin)
+#endif
+	    )
+    {
+	loff.lnum = curwin->w_cursor.lnum;
+#ifdef FEAT_DIFF
+	loff.fill = 0;
+	n = curwin->w_topfill;	    // always have this context
+#else
+	n = 0;
+#endif
+	// Count the visible screen lines above the cursor line.
+	while (n < so)
+	{
+	    topline_back(&loff);
+	    // Stop when included a line above the window.
+	    if (loff.lnum < curwin->w_topline
+#ifdef FEAT_DIFF
+		    || (loff.lnum == curwin->w_topline && loff.fill > 0)
+#endif
+		    )
+		break;
+	    n += loff.height;
+	}
+	if (n < so)
+	    return TRUE;
+    }
+    return FALSE;
+}
+
+/*
+ * Update w_curswant.
+ */
+    void
+update_curswant_force(void)
+{
+    validate_virtcol();
+    curwin->w_curswant = curwin->w_virtcol
+#ifdef FEAT_PROP_POPUP
+	- curwin->w_virtcol_first_char
+#endif
+	;
+    curwin->w_set_curswant = FALSE;
+}
+
+/*
+ * Update w_curswant if w_set_curswant is set.
+ */
+    void
+update_curswant(void)
+{
+    if (curwin->w_set_curswant)
+	update_curswant_force();
+}
+
+/*
+ * Check if the cursor has moved.  Set the w_valid flag accordingly.
+ */
+    void
+check_cursor_moved(win_T *wp)
+{
+    if (wp->w_cursor.lnum != wp->w_valid_cursor.lnum)
+    {
+	wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
+				      |VALID_CHEIGHT|VALID_CROW|VALID_TOPLINE
+				      |VALID_BOTLINE|VALID_BOTLINE_AP);
+	wp->w_valid_cursor = wp->w_cursor;
+	wp->w_valid_leftcol = wp->w_leftcol;
+	wp->w_valid_skipcol = wp->w_skipcol;
+    }
+    else if (wp->w_skipcol != wp->w_valid_skipcol)
+    {
+	wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
+				      |VALID_CHEIGHT|VALID_CROW
+				      |VALID_BOTLINE|VALID_BOTLINE_AP);
+	wp->w_valid_cursor = wp->w_cursor;
+	wp->w_valid_leftcol = wp->w_leftcol;
+	wp->w_valid_skipcol = wp->w_skipcol;
+    }
+    else if (wp->w_cursor.col != wp->w_valid_cursor.col
+	     || wp->w_leftcol != wp->w_valid_leftcol
+	     || wp->w_cursor.coladd != wp->w_valid_cursor.coladd)
+    {
+	wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL);
+	wp->w_valid_cursor.col = wp->w_cursor.col;
+	wp->w_valid_leftcol = wp->w_leftcol;
+	wp->w_valid_cursor.coladd = wp->w_cursor.coladd;
+    }
+}
+
+/*
+ * Call this function when some window settings have changed, which require
+ * the cursor position, botline and topline to be recomputed and the window to
+ * be redrawn.  E.g, when changing the 'wrap' option or folding.
+ */
+    void
+changed_window_setting(void)
+{
+    changed_window_setting_win(curwin);
+}
+
+    void
+changed_window_setting_win(win_T *wp)
+{
+    wp->w_lines_valid = 0;
+    changed_line_abv_curs_win(wp);
+    wp->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP|VALID_TOPLINE);
+    redraw_win_later(wp, UPD_NOT_VALID);
+}
+
+#if defined(FEAT_PROP_POPUP) || defined(PROTO)
+/*
+ * Call changed_window_setting_win() for every window containing "buf".
+ */
+    void
+changed_window_setting_buf(buf_T *buf)
+{
+    tabpage_T	*tp;
+    win_T	*wp;
+
+    FOR_ALL_TAB_WINDOWS(tp, wp)
+	if (wp->w_buffer == buf)
+	    changed_window_setting_win(wp);
+}
+#endif
+
+/*
+ * Set wp->w_topline to a certain number.
+ */
+    void
+set_topline(win_T *wp, linenr_T lnum)
+{
+#ifdef FEAT_DIFF
+    linenr_T prev_topline = wp->w_topline;
+#endif
+
+#ifdef FEAT_FOLDING
+    // go to first of folded lines
+    (void)hasFoldingWin(wp, lnum, &lnum, NULL, TRUE, NULL);
+#endif
+    // Approximate the value of w_botline
+    wp->w_botline += lnum - wp->w_topline;
+    if (wp->w_botline > wp->w_buffer->b_ml.ml_line_count + 1)
+	wp->w_botline = wp->w_buffer->b_ml.ml_line_count + 1;
+    wp->w_topline = lnum;
+    wp->w_topline_was_set = TRUE;
+#ifdef FEAT_DIFF
+    if (lnum != prev_topline)
+	// Keep the filler lines when the topline didn't change.
+	wp->w_topfill = 0;
+#endif
+    wp->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_TOPLINE);
+    // Don't set VALID_TOPLINE here, 'scrolloff' needs to be checked.
+    redraw_later(UPD_VALID);
+}
+
+/*
+ * Call this function when the length of the cursor line (in screen
+ * characters) has changed, and the change is before the cursor.
+ * If the line length changed the number of screen lines might change,
+ * requiring updating w_topline.  That may also invalidate w_crow.
+ * Need to take care of w_botline separately!
+ */
+    void
+changed_cline_bef_curs(void)
+{
+    curwin->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
+						|VALID_CHEIGHT|VALID_TOPLINE);
+}
+
+    void
+changed_cline_bef_curs_win(win_T *wp)
+{
+    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
+						|VALID_CHEIGHT|VALID_TOPLINE);
+}
+
+/*
+ * Call this function when the length of a line (in screen characters) above
+ * the cursor have changed.
+ * Need to take care of w_botline separately!
+ */
+    void
+changed_line_abv_curs(void)
+{
+    curwin->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
+						|VALID_CHEIGHT|VALID_TOPLINE);
+}
+
+    void
+changed_line_abv_curs_win(win_T *wp)
+{
+    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL|VALID_CROW
+						|VALID_CHEIGHT|VALID_TOPLINE);
+}
+
+#if defined(FEAT_PROP_POPUP) || defined(PROTO)
+/*
+ * Display of line has changed for "buf", invalidate cursor position and
+ * w_botline.
+ */
+    void
+changed_line_display_buf(buf_T *buf)
+{
+    win_T *wp;
+
+    FOR_ALL_WINDOWS(wp)
+	if (wp->w_buffer == buf)
+	    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
+				|VALID_CROW|VALID_CHEIGHT
+				|VALID_TOPLINE|VALID_BOTLINE|VALID_BOTLINE_AP);
+}
+#endif
+
+/*
+ * Make sure the value of curwin->w_botline is valid.
+ */
+    void
+validate_botline(void)
+{
+    validate_botline_win(curwin);
+}
+
+/*
+ * Make sure the value of wp->w_botline is valid.
+ */
+    void
+validate_botline_win(win_T *wp)
+{
+    if (!(wp->w_valid & VALID_BOTLINE))
+	comp_botline(wp);
+}
+
+/*
+ * Mark curwin->w_botline as invalid (because of some change in the buffer).
+ */
+    void
+invalidate_botline(void)
+{
+    curwin->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
+}
+
+    void
+invalidate_botline_win(win_T *wp)
+{
+    wp->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
+}
+
+    void
+approximate_botline_win(
+    win_T	*wp)
+{
+    wp->w_valid &= ~VALID_BOTLINE;
+}
+
+/*
+ * Return TRUE if curwin->w_wrow and curwin->w_wcol are valid.
+ */
+    int
+cursor_valid(void)
+{
+    check_cursor_moved(curwin);
+    return ((curwin->w_valid & (VALID_WROW|VALID_WCOL)) ==
+						      (VALID_WROW|VALID_WCOL));
+}
+
+/*
+ * Validate cursor position.  Makes sure w_wrow and w_wcol are valid.
+ * w_topline must be valid, you may need to call update_topline() first!
+ */
+    void
+validate_cursor(void)
+{
+    check_cursor_lnum();
+    check_cursor_moved(curwin);
+    if ((curwin->w_valid & (VALID_WCOL|VALID_WROW)) != (VALID_WCOL|VALID_WROW))
+	curs_columns(TRUE);
+}
+
+#if defined(FEAT_GUI) || defined(PROTO)
+/*
+ * validate w_cline_row.
+ */
+    void
+validate_cline_row(void)
+{
+    /*
+     * First make sure that w_topline is valid (after moving the cursor).
+     */
+    update_topline();
+    check_cursor_moved(curwin);
+    if (!(curwin->w_valid & VALID_CROW))
+	curs_rows(curwin);
+}
+#endif
+
+/*
+ * Compute wp->w_cline_row and wp->w_cline_height, based on the current value
+ * of wp->w_topline.
+ */
+    static void
+curs_rows(win_T *wp)
+{
+    linenr_T	lnum;
+    int		i;
+    int		all_invalid;
+    int		valid;
+#ifdef FEAT_FOLDING
+    long	fold_count;
+#endif
+
+    // Check if wp->w_lines[].wl_size is invalid
+    all_invalid = (!redrawing()
+			|| wp->w_lines_valid == 0
+			|| wp->w_lines[0].wl_lnum > wp->w_topline);
+    i = 0;
+    wp->w_cline_row = 0;
+    for (lnum = wp->w_topline; lnum < wp->w_cursor.lnum; ++i)
+    {
+	valid = FALSE;
+	if (!all_invalid && i < wp->w_lines_valid)
+	{
+	    if (wp->w_lines[i].wl_lnum < lnum || !wp->w_lines[i].wl_valid)
+		continue;		// skip changed or deleted lines
+	    if (wp->w_lines[i].wl_lnum == lnum)
+	    {
+#ifdef FEAT_FOLDING
+		// Check for newly inserted lines below this row, in which
+		// case we need to check for folded lines.
+		if (!wp->w_buffer->b_mod_set
+			|| wp->w_lines[i].wl_lastlnum < wp->w_cursor.lnum
+			|| wp->w_buffer->b_mod_top
+					     > wp->w_lines[i].wl_lastlnum + 1)
+#endif
+		valid = TRUE;
+	    }
+	    else if (wp->w_lines[i].wl_lnum > lnum)
+		--i;			// hold at inserted lines
+	}
+	if (valid
+	       && (lnum != wp->w_topline || (wp->w_skipcol == 0
+#ifdef FEAT_DIFF
+					    && !wp->w_p_diff
+#endif
+	       )))
+	{
+#ifdef FEAT_FOLDING
+	    lnum = wp->w_lines[i].wl_lastlnum + 1;
+	    // Cursor inside folded lines, don't count this row
+	    if (lnum > wp->w_cursor.lnum)
+		break;
+#else
+	    ++lnum;
+#endif
+	    wp->w_cline_row += wp->w_lines[i].wl_size;
+	}
+	else
+	{
+#ifdef FEAT_FOLDING
+	    fold_count = foldedCount(wp, lnum, NULL);
+	    if (fold_count)
+	    {
+		lnum += fold_count;
+		if (lnum > wp->w_cursor.lnum)
+		    break;
+		++wp->w_cline_row;
+	    }
+	    else
+#endif
+	    {
+		wp->w_cline_row += plines_correct_topline(wp, lnum);
+		++lnum;
+	    }
+	}
+    }
+
+    check_cursor_moved(wp);
+    if (!(wp->w_valid & VALID_CHEIGHT))
+    {
+	if (all_invalid
+		|| i == wp->w_lines_valid
+		|| (i < wp->w_lines_valid
+		    && (!wp->w_lines[i].wl_valid
+			|| wp->w_lines[i].wl_lnum != wp->w_cursor.lnum)))
+	{
+#ifdef FEAT_DIFF
+	    if (wp->w_cursor.lnum == wp->w_topline)
+		wp->w_cline_height = plines_win_nofill(wp, wp->w_cursor.lnum,
+							TRUE) + wp->w_topfill;
+	    else
+#endif
+		wp->w_cline_height = plines_win(wp, wp->w_cursor.lnum, TRUE);
+#ifdef FEAT_FOLDING
+	    wp->w_cline_folded = hasFoldingWin(wp, wp->w_cursor.lnum,
+						      NULL, NULL, TRUE, NULL);
+#endif
+	}
+	else if (i > wp->w_lines_valid)
+	{
+	    // a line that is too long to fit on the last screen line
+	    wp->w_cline_height = 0;
+#ifdef FEAT_FOLDING
+	    wp->w_cline_folded = hasFoldingWin(wp, wp->w_cursor.lnum,
+						      NULL, NULL, TRUE, NULL);
+#endif
+	}
+	else
+	{
+	    wp->w_cline_height = wp->w_lines[i].wl_size;
+#ifdef FEAT_FOLDING
+	    wp->w_cline_folded = wp->w_lines[i].wl_folded;
+#endif
+	}
+    }
+
+    redraw_for_cursorline(curwin);
+    wp->w_valid |= VALID_CROW|VALID_CHEIGHT;
+}
+
+/*
+ * Validate curwin->w_virtcol only.
+ */
+    void
+validate_virtcol(void)
+{
+    validate_virtcol_win(curwin);
+}
+
+/*
+ * Validate wp->w_virtcol only.
+ */
+    void
+validate_virtcol_win(win_T *wp)
+{
+    check_cursor_moved(wp);
+
+    if (wp->w_valid & VALID_VIRTCOL)
+	return;
+
+#ifdef FEAT_PROP_POPUP
+    wp->w_virtcol_first_char = 0;
+#endif
+    getvvcol(wp, &wp->w_cursor, NULL, &(wp->w_virtcol), NULL);
+#ifdef FEAT_SYN_HL
+    redraw_for_cursorcolumn(wp);
+#endif
+    wp->w_valid |= VALID_VIRTCOL;
+}
+
+/*
+ * Validate curwin->w_cline_height only.
+ */
+    void
+validate_cheight(void)
+{
+    check_cursor_moved(curwin);
+
+    if (curwin->w_valid & VALID_CHEIGHT)
+	return;
+
+#ifdef FEAT_DIFF
+    if (curwin->w_cursor.lnum == curwin->w_topline)
+	curwin->w_cline_height = plines_nofill(curwin->w_cursor.lnum)
+	    + curwin->w_topfill;
+    else
+#endif
+	curwin->w_cline_height = plines(curwin->w_cursor.lnum);
+#ifdef FEAT_FOLDING
+    curwin->w_cline_folded = hasFolding(curwin->w_cursor.lnum, NULL, NULL);
+#endif
+    curwin->w_valid |= VALID_CHEIGHT;
+}
+
+/*
+ * Validate w_wcol and w_virtcol only.
+ */
+    void
+validate_cursor_col(void)
+{
+    colnr_T off;
+    colnr_T col;
+    int     width;
+
+    validate_virtcol();
+
+    if (curwin->w_valid & VALID_WCOL)
+	return;
+
+    col = curwin->w_virtcol;
+    off = curwin_col_off();
+    col += off;
+    width = curwin->w_width - off + curwin_col_off2();
+
+    // long line wrapping, adjust curwin->w_wrow
+    if (curwin->w_p_wrap
+	    && col >= (colnr_T)curwin->w_width
+	    && width > 0)
+	// use same formula as what is used in curs_columns()
+	col -= ((col - curwin->w_width) / width + 1) * width;
+    if (col > (int)curwin->w_leftcol)
+	col -= curwin->w_leftcol;
+    else
+	col = 0;
+    curwin->w_wcol = col;
+
+    curwin->w_valid |= VALID_WCOL;
+#ifdef FEAT_PROP_POPUP
+    curwin->w_flags &= ~WFLAG_WCOL_OFF_ADDED;
+#endif
+}
+
+/*
+ * Compute offset of a window, occupied by absolute or relative line number,
+ * fold column and sign column (these don't move when scrolling horizontally).
+ */
+    int
+win_col_off(win_T *wp)
+{
+    return (((wp->w_p_nu || wp->w_p_rnu) ? number_width(wp) + 1 : 0)
+	    + (cmdwin_type == 0 || wp != curwin ? 0 : 1)
+#ifdef FEAT_FOLDING
+	    + wp->w_p_fdc
+#endif
+#ifdef FEAT_SIGNS
+	    + (signcolumn_on(wp) ? 2 : 0)
+#endif
+	   );
+}
+
+    int
+curwin_col_off(void)
+{
+    return win_col_off(curwin);
+}
+
+/*
+ * Return the difference in column offset for the second screen line of a
+ * wrapped line.  It's positive if 'number' or 'relativenumber' is on and 'n'
+ * is in 'cpoptions'.
+ */
+    int
+win_col_off2(win_T *wp)
+{
+    if ((wp->w_p_nu || wp->w_p_rnu) && vim_strchr(p_cpo, CPO_NUMCOL) != NULL)
+	return number_width(wp) + 1;
+    return 0;
+}
+
+    int
+curwin_col_off2(void)
+{
+    return win_col_off2(curwin);
+}
+
+/*
+ * Compute curwin->w_wcol and curwin->w_virtcol.
+ * Also updates curwin->w_wrow and curwin->w_cline_row.
+ * Also updates curwin->w_leftcol.
+ */
+    void
+curs_columns(
+    int		may_scroll)	// when TRUE, may scroll horizontally
+{
+    int		diff;
+    int		extra;		// offset for first screen line
+    int		off_left, off_right;
+    int		n;
+    int		p_lines;
+    int		width1;		// text width for first screen line
+    int		width2 = 0;	// text width for second and later screen line
+    int		new_leftcol;
+    colnr_T	startcol;
+    colnr_T	endcol;
+    colnr_T	prev_skipcol;
+    long	so = get_scrolloff_value();
+    long	siso = get_sidescrolloff_value();
+    int		did_sub_skipcol = FALSE;
+
+    /*
+     * First make sure that w_topline is valid (after moving the cursor).
+     */
+    update_topline();
+
+    /*
+     * Next make sure that w_cline_row is valid.
+     */
+    if (!(curwin->w_valid & VALID_CROW))
+	curs_rows(curwin);
+
+#ifdef FEAT_PROP_POPUP
+    // will be set by getvvcol() but not reset
+    curwin->w_virtcol_first_char = 0;
+#endif
+
+    /*
+     * Compute the number of virtual columns.
+     */
+#ifdef FEAT_FOLDING
+    if (curwin->w_cline_folded)
+	// In a folded line the cursor is always in the first column
+	startcol = curwin->w_virtcol = endcol = curwin->w_leftcol;
+    else
+#endif
+	getvvcol(curwin, &curwin->w_cursor,
+				&startcol, &(curwin->w_virtcol), &endcol);
+
+    // remove '$' from change command when cursor moves onto it
+    if (startcol > dollar_vcol)
+	dollar_vcol = -1;
+
+    extra = curwin_col_off();
+    curwin->w_wcol = curwin->w_virtcol + extra;
+    endcol += extra;
+
+    /*
+     * Now compute w_wrow, counting screen lines from w_cline_row.
+     */
+    curwin->w_wrow = curwin->w_cline_row;
+
+    width1 = curwin->w_width - extra;
+    if (width1 <= 0)
+    {
+	// No room for text, put cursor in last char of window.
+	// If not wrapping, the last non-empty line.
+	curwin->w_wcol = curwin->w_width - 1;
+	if (curwin->w_p_wrap)
+	    curwin->w_wrow = curwin->w_height - 1;
+	else
+	    curwin->w_wrow = curwin->w_height - 1 - curwin->w_empty_rows;
+    }
+    else if (curwin->w_p_wrap && curwin->w_width != 0)
+    {
+	width2 = width1 + curwin_col_off2();
+
+	// skip columns that are not visible
+	if (curwin->w_cursor.lnum == curwin->w_topline
+		&& curwin->w_skipcol > 0
+		&& curwin->w_wcol >= curwin->w_skipcol)
+	{
+	    // Deduct by multiples of width2.  This allows the long line
+	    // wrapping formula below to correctly calculate the w_wcol value
+	    // when wrapping.
+	    if (curwin->w_skipcol <= width1)
+		curwin->w_wcol -= width2;
+	    else
+		curwin->w_wcol -= width2
+			       * (((curwin->w_skipcol - width1) / width2) + 1);
+
+	    did_sub_skipcol = TRUE;
+	}
+
+	// long line wrapping, adjust curwin->w_wrow
+	if (curwin->w_wcol >= curwin->w_width)
+	{
+	    // this same formula is used in validate_cursor_col()
+	    n = (curwin->w_wcol - curwin->w_width) / width2 + 1;
+	    curwin->w_wcol -= n * width2;
+	    curwin->w_wrow += n;
+
+#ifdef FEAT_LINEBREAK
+	    // When cursor wraps to first char of next line in Insert
+	    // mode, the 'showbreak' string isn't shown, backup to first
+	    // column
+	    char_u *sbr = get_showbreak_value(curwin);
+	    if (*sbr && *ml_get_cursor() == NUL
+				    && curwin->w_wcol == vim_strsize(sbr))
+		curwin->w_wcol = 0;
+#endif
+	}
+    }
+
+    // No line wrapping: compute curwin->w_leftcol if scrolling is on and line
+    // is not folded.
+    // If scrolling is off, curwin->w_leftcol is assumed to be 0
+    else if (may_scroll
+#ifdef FEAT_FOLDING
+	    && !curwin->w_cline_folded
+#endif
+	    )
+    {
+#ifdef FEAT_PROP_POPUP
+	if (curwin->w_virtcol_first_char > 0)
+	{
+	    int cols = (curwin->w_width - extra);
+	    int rows = cols > 0 ? curwin->w_virtcol_first_char / cols : 1;
+
+	    // each "above" text prop shifts the text one row down
+	    curwin->w_wrow += rows;
+	    curwin->w_wcol -= rows * cols;
+	    endcol -= rows * cols;
+	    curwin->w_cline_height = rows + 1;
+	}
+#endif
+	/*
+	 * If Cursor is left of the screen, scroll rightwards.
+	 * If Cursor is right of the screen, scroll leftwards
+	 * If we get closer to the edge than 'sidescrolloff', scroll a little
+	 * extra
+	 */
+	off_left = (int)startcol - (int)curwin->w_leftcol - siso;
+	off_right = (int)endcol - (int)(curwin->w_leftcol + curwin->w_width
+								- siso) + 1;
+	if (off_left < 0 || off_right > 0)
+	{
+	    if (off_left < 0)
+		diff = -off_left;
+	    else
+		diff = off_right;
+
+	    // When far off or not enough room on either side, put cursor in
+	    // middle of window.
+	    if (p_ss == 0 || diff >= width1 / 2 || off_right >= off_left)
+		new_leftcol = curwin->w_wcol - extra - width1 / 2;
+	    else
+	    {
+		if (diff < p_ss)
+		    diff = p_ss;
+		if (off_left < 0)
+		    new_leftcol = curwin->w_leftcol - diff;
+		else
+		    new_leftcol = curwin->w_leftcol + diff;
+	    }
+	    if (new_leftcol < 0)
+		new_leftcol = 0;
+	    if (new_leftcol != (int)curwin->w_leftcol)
+	    {
+		curwin->w_leftcol = new_leftcol;
+		// screen has to be redrawn with new curwin->w_leftcol
+		redraw_later(UPD_NOT_VALID);
+	    }
+	}
+	curwin->w_wcol -= curwin->w_leftcol;
+    }
+    else if (curwin->w_wcol > (int)curwin->w_leftcol)
+	curwin->w_wcol -= curwin->w_leftcol;
+    else
+	curwin->w_wcol = 0;
+
+#ifdef FEAT_DIFF
+    // Skip over filler lines.  At the top use w_topfill, there
+    // may be some filler lines above the window.
+    if (curwin->w_cursor.lnum == curwin->w_topline)
+	curwin->w_wrow += curwin->w_topfill;
+    else
+	curwin->w_wrow += diff_check_fill(curwin, curwin->w_cursor.lnum);
+#endif
+
+    prev_skipcol = curwin->w_skipcol;
+
+    p_lines = 0;
+
+    if ((curwin->w_wrow >= curwin->w_height
+		|| ((prev_skipcol > 0
+			|| curwin->w_wrow + so >= curwin->w_height)
+		    && (p_lines =
+#ifdef FEAT_DIFF
+			plines_win_nofill
+#else
+			plines_win
+#endif
+			(curwin, curwin->w_cursor.lnum, FALSE))
+						    - 1 >= curwin->w_height))
+	    && curwin->w_height != 0
+	    && curwin->w_cursor.lnum == curwin->w_topline
+	    && width2 > 0
+	    && curwin->w_width != 0)
+    {
+	// Cursor past end of screen.  Happens with a single line that does
+	// not fit on screen.  Find a skipcol to show the text around the
+	// cursor.  Avoid scrolling all the time. compute value of "extra":
+	// 1: Less than 'scrolloff' lines above
+	// 2: Less than 'scrolloff' lines below
+	// 3: both of them
+	extra = 0;
+	if (curwin->w_skipcol + so * width2 > curwin->w_virtcol)
+	    extra = 1;
+	// Compute last display line of the buffer line that we want at the
+	// bottom of the window.
+	if (p_lines == 0)
+	    p_lines = plines_win(curwin, curwin->w_cursor.lnum, FALSE);
+	--p_lines;
+	if (p_lines > curwin->w_wrow + so)
+	    n = curwin->w_wrow + so;
+	else
+	    n = p_lines;
+	if ((colnr_T)n >= curwin->w_height + curwin->w_skipcol / width2 - so)
+	    extra += 2;
+
+	if (extra == 3 || curwin->w_height <= so * 2)
+	{
+	    // not enough room for 'scrolloff', put cursor in the middle
+	    n = curwin->w_virtcol / width2;
+	    if (n > curwin->w_height / 2)
+		n -= curwin->w_height / 2;
+	    else
+		n = 0;
+	    // don't skip more than necessary
+	    if (n > p_lines - curwin->w_height + 1)
+		n = p_lines - curwin->w_height + 1;
+	    curwin->w_skipcol = n * width2;
+	}
+	else if (extra == 1)
+	{
+	    // less than 'scrolloff' lines above, decrease skipcol
+	    extra = (curwin->w_skipcol + so * width2 - curwin->w_virtcol
+				     + width2 - 1) / width2;
+	    if (extra > 0)
+	    {
+		if ((colnr_T)(extra * width2) > curwin->w_skipcol)
+		    extra = curwin->w_skipcol / width2;
+		curwin->w_skipcol -= extra * width2;
+	    }
+	}
+	else if (extra == 2)
+	{
+	    // less than 'scrolloff' lines below, increase skipcol
+	    endcol = (n - curwin->w_height + 1) * width2;
+	    while (endcol > curwin->w_virtcol)
+		endcol -= width2;
+	    if (endcol > curwin->w_skipcol)
+		curwin->w_skipcol = endcol;
+	}
+
+	// adjust w_wrow for the changed w_skipcol
+	if (did_sub_skipcol)
+	    curwin->w_wrow -= (curwin->w_skipcol - prev_skipcol) / width2;
+	else
+	    curwin->w_wrow -= curwin->w_skipcol / width2;
+
+	if (curwin->w_wrow >= curwin->w_height)
+	{
+	    // small window, make sure cursor is in it
+	    extra = curwin->w_wrow - curwin->w_height + 1;
+	    curwin->w_skipcol += extra * width2;
+	    curwin->w_wrow -= extra;
+	}
+
+	extra = ((int)prev_skipcol - (int)curwin->w_skipcol) / width2;
+	if (extra > 0)
+	    win_ins_lines(curwin, 0, extra, FALSE, FALSE);
+	else if (extra < 0)
+	    win_del_lines(curwin, 0, -extra, FALSE, FALSE, 0);
+    }
+    else if (!curwin->w_p_sms)
+	curwin->w_skipcol = 0;
+    if (prev_skipcol != curwin->w_skipcol)
+	redraw_later(UPD_SOME_VALID);
+
+#ifdef FEAT_SYN_HL
+    redraw_for_cursorcolumn(curwin);
+#endif
+#if defined(FEAT_PROP_POPUP) && defined(FEAT_TERMINAL)
+    if (popup_is_popup(curwin) && curbuf->b_term != NULL)
+    {
+	curwin->w_wrow += popup_top_extra(curwin);
+	curwin->w_wcol += popup_left_extra(curwin);
+	curwin->w_flags |= WFLAG_WCOL_OFF_ADDED + WFLAG_WROW_OFF_ADDED;
+    }
+    else
+	curwin->w_flags &= ~(WFLAG_WCOL_OFF_ADDED + WFLAG_WROW_OFF_ADDED);
+#endif
+
+    // now w_leftcol and w_skipcol are valid, avoid check_cursor_moved()
+    // thinking otherwise
+    curwin->w_valid_leftcol = curwin->w_leftcol;
+    curwin->w_valid_skipcol = curwin->w_skipcol;
+
+    curwin->w_valid |= VALID_WCOL|VALID_WROW|VALID_VIRTCOL;
+}
+
+#if (defined(FEAT_EVAL) || defined(FEAT_PROP_POPUP)) || defined(PROTO)
+/*
+ * Compute the screen position of text character at "pos" in window "wp"
+ * The resulting values are one-based, zero when character is not visible.
+ */
+    void
+textpos2screenpos(
+	win_T	*wp,
+	pos_T	*pos,
+	int	*rowp,	// screen row
+	int	*scolp,	// start screen column
+	int	*ccolp,	// cursor screen column
+	int	*ecolp)	// end screen column
+{
+    colnr_T	scol = 0, ccol = 0, ecol = 0;
+    int		row = 0;
+    int		rowoff = 0;
+    colnr_T	coloff = 0;
+
+    if (pos->lnum >= wp->w_topline && pos->lnum <= wp->w_botline)
+    {
+	colnr_T	    col;
+	int	    width;
+	linenr_T    lnum = pos->lnum;
+#ifdef FEAT_FOLDING
+	int	    is_folded;
+
+	is_folded = hasFoldingWin(wp, lnum, &lnum, NULL, TRUE, NULL);
+#endif
+	row = plines_m_win(wp, wp->w_topline, lnum - 1) + 1;
+
+#ifdef FEAT_DIFF
+	// Add filler lines above this buffer line.
+	row += lnum == wp->w_topline ? wp->w_topfill
+				     : diff_check_fill(wp, lnum);
+#endif
+
+	colnr_T	off = win_col_off(wp);
+#ifdef FEAT_FOLDING
+	if (is_folded)
+	{
+	    row += W_WINROW(wp);
+	    coloff = wp->w_wincol + 1 + off;
+	}
+	else
+#endif
+	{
+	    getvcol(wp, pos, &scol, &ccol, &ecol);
+
+	    // similar to what is done in validate_cursor_col()
+	    col = scol;
+	    col += off;
+	    width = wp->w_width - off + win_col_off2(wp);
+
+	    if (lnum == wp->w_topline)
+		col -= wp->w_skipcol;
+
+	    // long line wrapping, adjust row
+	    if (wp->w_p_wrap
+		    && col >= (colnr_T)wp->w_width
+		    && width > 0)
+	    {
+		// use same formula as what is used in curs_columns()
+		rowoff = ((col - wp->w_width) / width + 1);
+		col -= rowoff * width;
+	    }
+	    col -= wp->w_leftcol;
+	    if (col >= wp->w_width)
+		col = -1;
+	    if (col >= 0 && row + rowoff <= wp->w_height)
+	    {
+		coloff = col - scol + wp->w_wincol + 1;
+		row += W_WINROW(wp);
+	    }
+	    else
+		// character is left, right or below of the window
+		row = rowoff = scol = ccol = ecol = 0;
+	}
+    }
+    *rowp = row + rowoff;
+    *scolp = scol + coloff;
+    *ccolp = ccol + coloff;
+    *ecolp = ecol + coloff;
+}
+#endif
+
+#if defined(FEAT_EVAL) || defined(PROTO)
+/*
+ * "screenpos({winid}, {lnum}, {col})" function
+ */
+    void
+f_screenpos(typval_T *argvars UNUSED, typval_T *rettv)
+{
+    dict_T	*dict;
+    win_T	*wp;
+    pos_T	pos;
+    int		row = 0;
+    int		scol = 0, ccol = 0, ecol = 0;
+
+    if (rettv_dict_alloc(rettv) == FAIL)
+	return;
+    dict = rettv->vval.v_dict;
+
+    if (in_vim9script()
+	    && (check_for_number_arg(argvars, 0) == FAIL
+		|| check_for_number_arg(argvars, 1) == FAIL
+		|| check_for_number_arg(argvars, 2) == FAIL))
+	return;
+
+    wp = find_win_by_nr_or_id(&argvars[0]);
+    if (wp == NULL)
+	return;
+
+    pos.lnum = tv_get_number(&argvars[1]);
+    if (pos.lnum > wp->w_buffer->b_ml.ml_line_count)
+    {
+	semsg(_(e_invalid_line_number_nr), pos.lnum);
+	return;
+    }
+    pos.col = tv_get_number(&argvars[2]) - 1;
+    pos.coladd = 0;
+    textpos2screenpos(wp, &pos, &row, &scol, &ccol, &ecol);
+
+    dict_add_number(dict, "row", row);
+    dict_add_number(dict, "col", scol);
+    dict_add_number(dict, "curscol", ccol);
+    dict_add_number(dict, "endcol", ecol);
+}
+
+/*
+ * "virtcol2col({winid}, {lnum}, {col})" function
+ */
+    void
+f_virtcol2col(typval_T *argvars UNUSED, typval_T *rettv)
+{
+    win_T	*wp;
+    linenr_T	lnum;
+    int		screencol;
+    int		error = FALSE;
+
+    rettv->vval.v_number = -1;
+
+    if (check_for_number_arg(argvars, 0) == FAIL
+	    || check_for_number_arg(argvars, 1) == FAIL
+	    || check_for_number_arg(argvars, 2) == FAIL)
+	return;
+
+    wp = find_win_by_nr_or_id(&argvars[0]);
+    if (wp == NULL)
+	return;
+
+    lnum = tv_get_number_chk(&argvars[1], &error);
+    if (error || lnum < 0 || lnum > wp->w_buffer->b_ml.ml_line_count)
+	return;
+
+    screencol = tv_get_number_chk(&argvars[2], &error);
+    if (error || screencol < 0)
+	return;
+
+    rettv->vval.v_number = vcol2col(wp, lnum, screencol);
+}
+#endif
+
+/*
+ * Scroll the current window down by "line_count" logical lines.  "CTRL-Y"
+ */
+    void
+scrolldown(
+    long	line_count,
+    int		byfold UNUSED)	// TRUE: count a closed fold as one line
+{
+    long	done = 0;	// total # of physical lines done
+    int		wrow;
+    int		moved = FALSE;
+    int		do_sms = curwin->w_p_wrap && curwin->w_p_sms;
+    int		width1 = 0;
+    int		width2 = 0;
+
+    if (do_sms)
+    {
+	width1 = curwin->w_width - curwin_col_off();
+	width2 = width1 + curwin_col_off2();
+    }
+
+#ifdef FEAT_FOLDING
+    linenr_T	first;
+
+    // Make sure w_topline is at the first of a sequence of folded lines.
+    (void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+    validate_cursor();		// w_wrow needs to be valid
+    for (int todo = line_count; todo > 0; --todo)
+    {
+#ifdef FEAT_DIFF
+	if (curwin->w_topfill < diff_check(curwin, curwin->w_topline)
+		&& curwin->w_topfill < curwin->w_height - 1)
+	{
+	    ++curwin->w_topfill;
+	    ++done;
+	}
+	else
+#endif
+	{
+	    // break when at the very top
+	    if (curwin->w_topline == 1
+				   && (!do_sms || curwin->w_skipcol < width1))
+		break;
+	    if (do_sms && curwin->w_skipcol >= width1)
+	    {
+		// scroll a screen line down
+		if (curwin->w_skipcol >= width1 + width2)
+		    curwin->w_skipcol -= width2;
+		else
+		    curwin->w_skipcol -= width1;
+		redraw_later(UPD_NOT_VALID);
+		++done;
+	    }
+	    else
+	    {
+		// scroll a text line down
+		--curwin->w_topline;
+		curwin->w_skipcol = 0;
+#ifdef FEAT_DIFF
+		curwin->w_topfill = 0;
+#endif
+#ifdef FEAT_FOLDING
+		// A sequence of folded lines only counts for one logical line
+		if (hasFolding(curwin->w_topline, &first, NULL))
+		{
+		    ++done;
+		    if (!byfold)
+			todo -= curwin->w_topline - first - 1;
+		    curwin->w_botline -= curwin->w_topline - first;
+		    curwin->w_topline = first;
+		}
+		else
+#endif
+		if (do_sms)
+		{
+		    int size = win_linetabsize(curwin, curwin->w_topline,
+				   ml_get(curwin->w_topline), (colnr_T)MAXCOL);
+		    if (size > width1)
+		    {
+			curwin->w_skipcol = width1;
+			size -= width1;
+			redraw_later(UPD_NOT_VALID);
+		    }
+		    while (size > width2)
+		    {
+			curwin->w_skipcol += width2;
+			size -= width2;
+		    }
+		    ++done;
+		}
+		else
+		    done += PLINES_NOFILL(curwin->w_topline);
+	    }
+	}
+	--curwin->w_botline;		// approximate w_botline
+	invalidate_botline();
+    }
+    curwin->w_wrow += done;		// keep w_wrow updated
+    curwin->w_cline_row += done;	// keep w_cline_row updated
+
+#ifdef FEAT_DIFF
+    if (curwin->w_cursor.lnum == curwin->w_topline)
+	curwin->w_cline_row = 0;
+    check_topfill(curwin, TRUE);
+#endif
+
+    /*
+     * Compute the row number of the last row of the cursor line
+     * and move the cursor onto the displayed part of the window.
+     */
+    wrow = curwin->w_wrow;
+    if (curwin->w_p_wrap && curwin->w_width != 0)
+    {
+	validate_virtcol();
+	validate_cheight();
+	wrow += curwin->w_cline_height - 1 -
+	    curwin->w_virtcol / curwin->w_width;
+    }
+    while (wrow >= curwin->w_height && curwin->w_cursor.lnum > 1)
+    {
+#ifdef FEAT_FOLDING
+	if (hasFolding(curwin->w_cursor.lnum, &first, NULL))
+	{
+	    --wrow;
+	    if (first == 1)
+		curwin->w_cursor.lnum = 1;
+	    else
+		curwin->w_cursor.lnum = first - 1;
+	}
+	else
+#endif
+	    wrow -= plines(curwin->w_cursor.lnum--);
+	curwin->w_valid &=
+	      ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW|VALID_VIRTCOL);
+	moved = TRUE;
+    }
+    if (moved)
+    {
+#ifdef FEAT_FOLDING
+	// Move cursor to first line of closed fold.
+	foldAdjustCursor();
+#endif
+	coladvance(curwin->w_curswant);
+    }
+
+    if (curwin->w_cursor.lnum == curwin->w_topline && do_sms)
+    {
+	long	so = get_scrolloff_value();
+	int	scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
+
+	// make sure the cursor is in the visible text
+	validate_virtcol();
+	int col = curwin->w_virtcol - curwin->w_skipcol + scrolloff_cols;
+	int row = 0;
+	if (col >= width1)
+	{
+	    col -= width1;
+	    ++row;
+	}
+	if (col > width2 && width2 > 0)
+	{
+	    row += col / width2;
+	    col = col % width2;
+	}
+	if (row >= curwin->w_height)
+	{
+	    curwin->w_curswant = curwin->w_virtcol
+				       - (row - curwin->w_height + 1) * width2;
+	    coladvance(curwin->w_curswant);
+	}
+    }
+}
+
+/*
+ * Scroll the current window up by "line_count" logical lines.  "CTRL-E"
+ */
+    void
+scrollup(
+    long	line_count,
+    int		byfold UNUSED)	// TRUE: count a closed fold as one line
+{
+    int		do_sms = curwin->w_p_wrap && curwin->w_p_sms;
+
+    if (do_sms
+# ifdef FEAT_FOLDING
+	    || (byfold && hasAnyFolding(curwin))
+# endif
+# ifdef FEAT_DIFF
+	    || (curwin->w_p_diff && !curwin->w_p_wrap)
+# endif
+       )
+    {
+	int	    width1 = curwin->w_width - curwin_col_off();
+	int	    width2 = width1 + curwin_col_off2();
+	int	    size = 0;
+	colnr_T	    prev_skipcol = curwin->w_skipcol;
+
+	if (do_sms)
+	    size = linetabsize(curwin, curwin->w_topline);
+
+	// diff mode: first consume "topfill"
+	// 'smoothscroll': increase "w_skipcol" until it goes over the end of
+	// the line, then advance to the next line.
+	// folding: count each sequence of folded lines as one logical line.
+	for (int todo = line_count; todo > 0; --todo)
+	{
+# ifdef FEAT_DIFF
+	    if (curwin->w_topfill > 0)
+		--curwin->w_topfill;
+	    else
+# endif
+	    {
+		linenr_T lnum = curwin->w_topline;
+
+# ifdef FEAT_FOLDING
+		if (byfold)
+		    // for a closed fold: go to the last line in the fold
+		    (void)hasFolding(lnum, NULL, &lnum);
+# endif
+		if (lnum == curwin->w_topline && do_sms)
+		{
+		    // 'smoothscroll': increase "w_skipcol" until it goes over
+		    // the end of the line, then advance to the next line.
+		    int add = curwin->w_skipcol > 0 ? width2 : width1;
+		    curwin->w_skipcol += add;
+		    if (curwin->w_skipcol >= size)
+		    {
+			if (lnum == curbuf->b_ml.ml_line_count)
+			{
+			    // at the last screen line, can't scroll further
+			    curwin->w_skipcol -= add;
+			    break;
+			}
+			++lnum;
+		    }
+		}
+		else
+		{
+		    if (lnum >= curbuf->b_ml.ml_line_count)
+			break;
+		    ++lnum;
+		}
+
+		if (lnum > curwin->w_topline)
+		{
+		    // approximate w_botline
+		    curwin->w_botline += lnum - curwin->w_topline;
+		    curwin->w_topline = lnum;
+# ifdef FEAT_DIFF
+		    curwin->w_topfill = diff_check_fill(curwin, lnum);
+# endif
+		    curwin->w_skipcol = 0;
+		    if (todo > 1 && do_sms)
+			size = linetabsize(curwin, curwin->w_topline);
+		}
+	    }
+	}
+
+	if (prev_skipcol > 0 || curwin->w_skipcol > 0)
+	    // need to redraw more, because wl_size of the (new) topline may
+	    // now be invalid
+	    redraw_later(UPD_NOT_VALID);
+    }
+    else
+    {
+	curwin->w_topline += line_count;
+	curwin->w_botline += line_count;	// approximate w_botline
+    }
+
+    if (curwin->w_topline > curbuf->b_ml.ml_line_count)
+	curwin->w_topline = curbuf->b_ml.ml_line_count;
+    if (curwin->w_botline > curbuf->b_ml.ml_line_count + 1)
+	curwin->w_botline = curbuf->b_ml.ml_line_count + 1;
+
+#ifdef FEAT_DIFF
+    check_topfill(curwin, FALSE);
+#endif
+
+#ifdef FEAT_FOLDING
+    if (hasAnyFolding(curwin))
+	// Make sure w_topline is at the first of a sequence of folded lines.
+	(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+
+    curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
+    if (curwin->w_cursor.lnum < curwin->w_topline)
+    {
+	curwin->w_cursor.lnum = curwin->w_topline;
+	curwin->w_valid &=
+	      ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW|VALID_VIRTCOL);
+	coladvance(curwin->w_curswant);
+    }
+    if (curwin->w_cursor.lnum == curwin->w_topline
+					    && do_sms && curwin->w_skipcol > 0)
+    {
+	int	col_off = curwin_col_off();
+	int	col_off2 = curwin_col_off2();
+
+	int	width1 = curwin->w_width - col_off;
+	int	width2 = width1 + col_off2;
+	int	extra2 = col_off - col_off2;
+	long	so = get_scrolloff_value();
+	int	scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
+	int	space_cols = (curwin->w_height - 1) * width2;
+
+	// If we have non-zero scrolloff, just ignore the marker as we are
+	// going past it anyway.
+	int overlap = scrolloff_cols != 0 ? 0
+					  : sms_marker_overlap(curwin, extra2);
+
+	// Make sure the cursor is in a visible part of the line, taking
+	// 'scrolloff' into account, but using screen lines.
+	// If there are not enough screen lines put the cursor in the middle.
+	if (scrolloff_cols > space_cols / 2)
+	    scrolloff_cols = space_cols / 2;
+	validate_virtcol();
+	if (curwin->w_virtcol < curwin->w_skipcol + overlap + scrolloff_cols)
+	{
+	    colnr_T col = curwin->w_virtcol;
+
+	    if (col < width1)
+		col += width1;
+	    while (col < curwin->w_skipcol + overlap + scrolloff_cols)
+		col += width2;
+	    curwin->w_curswant = col;
+	    coladvance(curwin->w_curswant);
+
+	    // validate_virtcol() marked various things as valid, but after
+	    // moving the cursor they need to be recomputed
+	    curwin->w_valid &=
+	       ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW|VALID_VIRTCOL);
+	}
+    }
+}
+
+/*
+ * Called after changing the cursor column: make sure that curwin->w_skipcol is
+ * valid for 'smoothscroll'.
+ */
+    void
+adjust_skipcol(void)
+{
+    if (!curwin->w_p_wrap
+	    || !curwin->w_p_sms
+	    || curwin->w_cursor.lnum != curwin->w_topline)
+	return;
+
+    int	    width1 = curwin->w_width - curwin_col_off();
+    if (width1 <= 0)
+	return;  // no text will be displayed
+
+    int	    width2 = width1 + curwin_col_off2();
+    long    so = get_scrolloff_value();
+    int	    scrolloff_cols = so == 0 ? 0 : width1 + (so - 1) * width2;
+    int	    scrolled = FALSE;
+
+    validate_cheight();
+    if (curwin->w_cline_height == curwin->w_height
+	    // w_cline_height may be capped at w_height, check there aren't
+	    // actually more lines.
+	    && plines_win(curwin, curwin->w_cursor.lnum, FALSE)
+							   <= curwin->w_height)
+    {
+	// the line just fits in the window, don't scroll
+	reset_skipcol();
+	return;
+    }
+
+    validate_virtcol();
+    int overlap = sms_marker_overlap(curwin,
+					 curwin_col_off() - curwin_col_off2());
+    while (curwin->w_skipcol > 0
+	    && curwin->w_virtcol < curwin->w_skipcol + overlap + scrolloff_cols)
+    {
+	// scroll a screen line down
+	if (curwin->w_skipcol >= width1 + width2)
+	    curwin->w_skipcol -= width2;
+	else
+	    curwin->w_skipcol -= width1;
+	scrolled = TRUE;
+    }
+    if (scrolled)
+    {
+	validate_virtcol();
+	redraw_later(UPD_NOT_VALID);
+	return;  // don't scroll in the other direction now
+    }
+
+    int col = curwin->w_virtcol - curwin->w_skipcol + scrolloff_cols;
+    int row = 0;
+    if (col >= width1)
+    {
+	col -= width1;
+	++row;
+    }
+    if (col > width2)
+    {
+	row += col / width2;
+	col = col % width2;
+    }
+    if (row >= curwin->w_height)
+    {
+	if (curwin->w_skipcol == 0)
+	{
+	    curwin->w_skipcol += width1;
+	    --row;
+	}
+	if (row >= curwin->w_height)
+	    curwin->w_skipcol += (row - curwin->w_height) * width2;
+	redraw_later(UPD_NOT_VALID);
+    }
+}
+
+#ifdef FEAT_DIFF
+/*
+ * Don't end up with too many filler lines in the window.
+ */
+    void
+check_topfill(
+    win_T	*wp,
+    int		down)	// when TRUE scroll down when not enough space
+{
+    int		n;
+
+    if (wp->w_topfill <= 0)
+	return;
+
+    n = plines_win_nofill(wp, wp->w_topline, TRUE);
+    if (wp->w_topfill + n > wp->w_height)
+    {
+	if (down && wp->w_topline > 1)
+	{
+	    --wp->w_topline;
+	    wp->w_topfill = 0;
+	}
+	else
+	{
+	    wp->w_topfill = wp->w_height - n;
+	    if (wp->w_topfill < 0)
+		wp->w_topfill = 0;
+	}
+    }
+}
+
+/*
+ * Use as many filler lines as possible for w_topline.  Make sure w_topline
+ * is still visible.
+ */
+    static void
+max_topfill(void)
+{
+    int		n;
+
+    n = plines_nofill(curwin->w_topline);
+    if (n >= curwin->w_height)
+	curwin->w_topfill = 0;
+    else
+    {
+	curwin->w_topfill = diff_check_fill(curwin, curwin->w_topline);
+	if (curwin->w_topfill + n > curwin->w_height)
+	    curwin->w_topfill = curwin->w_height - n;
+    }
+}
+#endif
+
+/*
+ * Scroll the screen one line down, but don't do it if it would move the
+ * cursor off the screen.
+ */
+    void
+scrolldown_clamp(void)
+{
+    int		end_row;
+#ifdef FEAT_DIFF
+    int		can_fill = (curwin->w_topfill
+				< diff_check_fill(curwin, curwin->w_topline));
+#endif
+
+    if (curwin->w_topline <= 1
+#ifdef FEAT_DIFF
+	    && !can_fill
+#endif
+	    )
+	return;
+
+    validate_cursor();	    // w_wrow needs to be valid
+
+    /*
+     * Compute the row number of the last row of the cursor line
+     * and make sure it doesn't go off the screen. Make sure the cursor
+     * doesn't go past 'scrolloff' lines from the screen end.
+     */
+    end_row = curwin->w_wrow;
+#ifdef FEAT_DIFF
+    if (can_fill)
+	++end_row;
+    else
+	end_row += plines_nofill(curwin->w_topline - 1);
+#else
+    end_row += plines(curwin->w_topline - 1);
+#endif
+    if (curwin->w_p_wrap && curwin->w_width != 0)
+    {
+	validate_cheight();
+	validate_virtcol();
+	end_row += curwin->w_cline_height - 1 -
+	    curwin->w_virtcol / curwin->w_width;
+    }
+    if (end_row < curwin->w_height - get_scrolloff_value())
+    {
+#ifdef FEAT_DIFF
+	if (can_fill)
+	{
+	    ++curwin->w_topfill;
+	    check_topfill(curwin, TRUE);
+	}
+	else
+	{
+	    --curwin->w_topline;
+	    curwin->w_topfill = 0;
+	}
+#else
+	--curwin->w_topline;
+#endif
+#ifdef FEAT_FOLDING
+	(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+	--curwin->w_botline;	    // approximate w_botline
+	curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
+    }
+}
+
+/*
+ * Scroll the screen one line up, but don't do it if it would move the cursor
+ * off the screen.
+ */
+    void
+scrollup_clamp(void)
+{
+    int	    start_row;
+
+    if (curwin->w_topline == curbuf->b_ml.ml_line_count
+#ifdef FEAT_DIFF
+	    && curwin->w_topfill == 0
+#endif
+	    )
+	return;
+
+    validate_cursor();	    // w_wrow needs to be valid
+
+    /*
+     * Compute the row number of the first row of the cursor line
+     * and make sure it doesn't go off the screen. Make sure the cursor
+     * doesn't go before 'scrolloff' lines from the screen start.
+     */
+#ifdef FEAT_DIFF
+    start_row = curwin->w_wrow - plines_nofill(curwin->w_topline)
+							  - curwin->w_topfill;
+#else
+    start_row = curwin->w_wrow - plines(curwin->w_topline);
+#endif
+    if (curwin->w_p_wrap && curwin->w_width != 0)
+    {
+	validate_virtcol();
+	start_row -= curwin->w_virtcol / curwin->w_width;
+    }
+    if (start_row >= get_scrolloff_value())
+    {
+#ifdef FEAT_DIFF
+	if (curwin->w_topfill > 0)
+	    --curwin->w_topfill;
+	else
+#endif
+	{
+#ifdef FEAT_FOLDING
+	    (void)hasFolding(curwin->w_topline, NULL, &curwin->w_topline);
+#endif
+	    ++curwin->w_topline;
+	}
+	++curwin->w_botline;		// approximate w_botline
+	curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
+    }
+}
+
+/*
+ * Add one line above "lp->lnum".  This can be a filler line, a closed fold or
+ * a (wrapped) text line.  Uses and sets "lp->fill".
+ * Returns the height of the added line in "lp->height".
+ * Lines above the first one are incredibly high: MAXCOL.
+ */
+    static void
+topline_back_winheight(
+    lineoff_T	*lp,
+    int		winheight)	// when TRUE limit to window height
+{
+#ifdef FEAT_DIFF
+    if (lp->fill < diff_check_fill(curwin, lp->lnum))
+    {
+	// Add a filler line.
+	++lp->fill;
+	lp->height = 1;
+    }
+    else
+#endif
+    {
+	--lp->lnum;
+#ifdef FEAT_DIFF
+	lp->fill = 0;
+#endif
+	if (lp->lnum < 1)
+	    lp->height = MAXCOL;
+	else
+#ifdef FEAT_FOLDING
+	    if (hasFolding(lp->lnum, &lp->lnum, NULL))
+	    // Add a closed fold
+	    lp->height = 1;
+	else
+#endif
+	    lp->height = PLINES_WIN_NOFILL(curwin, lp->lnum, winheight);
+    }
+}
+
+    static void
+topline_back(lineoff_T *lp)
+{
+    topline_back_winheight(lp, TRUE);
+}
+
+
+/*
+ * Add one line below "lp->lnum".  This can be a filler line, a closed fold or
+ * a (wrapped) text line.  Uses and sets "lp->fill".
+ * Returns the height of the added line in "lp->height".
+ * Lines below the last one are incredibly high.
+ */
+    static void
+botline_forw(lineoff_T *lp)
+{
+#ifdef FEAT_DIFF
+    if (lp->fill < diff_check_fill(curwin, lp->lnum + 1))
+    {
+	// Add a filler line.
+	++lp->fill;
+	lp->height = 1;
+    }
+    else
+#endif
+    {
+	++lp->lnum;
+#ifdef FEAT_DIFF
+	lp->fill = 0;
+#endif
+	if (lp->lnum > curbuf->b_ml.ml_line_count)
+	    lp->height = MAXCOL;
+	else
+#ifdef FEAT_FOLDING
+	    if (hasFolding(lp->lnum, NULL, &lp->lnum))
+	    // Add a closed fold
+	    lp->height = 1;
+	else
+#endif
+	    lp->height = PLINES_NOFILL(lp->lnum);
+    }
+}
+
+#ifdef FEAT_DIFF
+/*
+ * Switch from including filler lines below lp->lnum to including filler
+ * lines above loff.lnum + 1.  This keeps pointing to the same line.
+ * When there are no filler lines nothing changes.
+ */
+    static void
+botline_topline(lineoff_T *lp)
+{
+    if (lp->fill > 0)
+    {
+	++lp->lnum;
+	lp->fill = diff_check_fill(curwin, lp->lnum) - lp->fill + 1;
+    }
+}
+
+/*
+ * Switch from including filler lines above lp->lnum to including filler
+ * lines below loff.lnum - 1.  This keeps pointing to the same line.
+ * When there are no filler lines nothing changes.
+ */
+    static void
+topline_botline(lineoff_T *lp)
+{
+    if (lp->fill > 0)
+    {
+	lp->fill = diff_check_fill(curwin, lp->lnum) - lp->fill + 1;
+	--lp->lnum;
+    }
+}
+#endif
+
+/*
+ * Recompute topline to put the cursor at the top of the window.
+ * Scroll at least "min_scroll" lines.
+ * If "always" is TRUE, always set topline (for "zt").
+ */
+    void
+scroll_cursor_top(int min_scroll, int always)
+{
+    int		scrolled = 0;
+    int		extra = 0;
+    int		used;
+    int		i;
+    linenr_T	top;		// just above displayed lines
+    linenr_T	bot;		// just below displayed lines
+    linenr_T	old_topline = curwin->w_topline;
+    int		old_skipcol = curwin->w_skipcol;
+#ifdef FEAT_DIFF
+    linenr_T	old_topfill = curwin->w_topfill;
+#endif
+    linenr_T	new_topline;
+    int		off = get_scrolloff_value();
+
+    if (mouse_dragging > 0)
+	off = mouse_dragging - 1;
+
+    /*
+     * Decrease topline until:
+     * - it has become 1
+     * - (part of) the cursor line is moved off the screen or
+     * - moved at least 'scrolljump' lines and
+     * - at least 'scrolloff' lines above and below the cursor
+     */
+    validate_cheight();
+    used = curwin->w_cline_height; // includes filler lines above
+    if (curwin->w_cursor.lnum < curwin->w_topline)
+	scrolled = used;
+
+#ifdef FEAT_FOLDING
+    if (hasFolding(curwin->w_cursor.lnum, &top, &bot))
+    {
+	--top;
+	++bot;
+    }
+    else
+#endif
+    {
+	top = curwin->w_cursor.lnum - 1;
+	bot = curwin->w_cursor.lnum + 1;
+    }
+    new_topline = top + 1;
+
+#ifdef FEAT_DIFF
+    // "used" already contains the number of filler lines above, don't add it
+    // again.
+    // Hide filler lines above cursor line by adding them to "extra".
+    extra += diff_check_fill(curwin, curwin->w_cursor.lnum);
+#endif
+
+    /*
+     * Check if the lines from "top" to "bot" fit in the window.  If they do,
+     * set new_topline and advance "top" and "bot" to include more lines.
+     */
+    while (top > 0)
+    {
+#ifdef FEAT_FOLDING
+	if (hasFolding(top, &top, NULL))
+	    // count one logical line for a sequence of folded lines
+	    i = 1;
+	else
+#endif
+	    i = PLINES_NOFILL(top);
+	if (top < curwin->w_topline)
+	    scrolled += i;
+
+	// If scrolling is needed, scroll at least 'sj' lines.
+	if ((new_topline >= curwin->w_topline || scrolled > min_scroll)
+		&& extra >= off)
+	    break;
+
+	used += i;
+	if (extra + i <= off && bot < curbuf->b_ml.ml_line_count)
+	{
+#ifdef FEAT_FOLDING
+	    if (hasFolding(bot, NULL, &bot))
+		// count one logical line for a sequence of folded lines
+		++used;
+	    else
+#endif
+		used += plines(bot);
+	}
+	if (used > curwin->w_height)
+	    break;
+
+	extra += i;
+	new_topline = top;
+	--top;
+	++bot;
+    }
+
+    /*
+     * If we don't have enough space, put cursor in the middle.
+     * This makes sure we get the same position when using "k" and "j"
+     * in a small window.
+     */
+    if (used > curwin->w_height)
+	scroll_cursor_halfway(FALSE, FALSE);
+    else
+    {
+	/*
+	 * If "always" is FALSE, only adjust topline to a lower value, higher
+	 * value may happen with wrapping lines.
+	 */
+	if (new_topline < curwin->w_topline || always)
+	    curwin->w_topline = new_topline;
+	if (curwin->w_topline > curwin->w_cursor.lnum)
+	    curwin->w_topline = curwin->w_cursor.lnum;
+#ifdef FEAT_DIFF
+	curwin->w_topfill = diff_check_fill(curwin, curwin->w_topline);
+	if (curwin->w_topfill > 0 && extra > off)
+	{
+	    curwin->w_topfill -= extra - off;
+	    if (curwin->w_topfill < 0)
+		curwin->w_topfill = 0;
+	}
+	check_topfill(curwin, FALSE);
+#endif
+	if (curwin->w_topline == curwin->w_cursor.lnum)
+	{
+	    validate_virtcol();
+	    if (curwin->w_skipcol >= curwin->w_virtcol)
+		// TODO: if the line doesn't fit may optimize w_skipcol instead
+		// of making it zero
+		reset_skipcol();
+	}
+	if (curwin->w_topline != old_topline
+		|| curwin->w_skipcol != old_skipcol
+#ifdef FEAT_DIFF
+		|| curwin->w_topfill != old_topfill
+#endif
+		)
+	    curwin->w_valid &=
+		      ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
+	curwin->w_valid |= VALID_TOPLINE;
+    }
+}
+
+/*
+ * Set w_empty_rows and w_filler_rows for window "wp", having used up "used"
+ * screen lines for text lines.
+ */
+    void
+set_empty_rows(win_T *wp, int used)
+{
+#ifdef FEAT_DIFF
+    wp->w_filler_rows = 0;
+#endif
+    if (used == 0)
+	wp->w_empty_rows = 0;	// single line that doesn't fit
+    else
+    {
+	wp->w_empty_rows = wp->w_height - used;
+#ifdef FEAT_DIFF
+	if (wp->w_botline <= wp->w_buffer->b_ml.ml_line_count)
+	{
+	    wp->w_filler_rows = diff_check_fill(wp, wp->w_botline);
+	    if (wp->w_empty_rows > wp->w_filler_rows)
+		wp->w_empty_rows -= wp->w_filler_rows;
+	    else
+	    {
+		wp->w_filler_rows = wp->w_empty_rows;
+		wp->w_empty_rows = 0;
+	    }
+	}
+#endif
+    }
+}
+
+/*
+ * Recompute topline to put the cursor at the bottom of the window.
+ * When scrolling scroll at least "min_scroll" lines.
+ * If "set_topbot" is TRUE, set topline and botline first (for "zb").
+ * This is messy stuff!!!
+ */
+    void
+scroll_cursor_bot(int min_scroll, int set_topbot)
+{
+    int		used;
+    int		scrolled = 0;
+    int		extra = 0;
+    int		i;
+    linenr_T	line_count;
+    linenr_T	old_topline = curwin->w_topline;
+    int		old_skipcol = curwin->w_skipcol;
+    lineoff_T	loff;
+    lineoff_T	boff;
+#ifdef FEAT_DIFF
+    int		old_topfill = curwin->w_topfill;
+    int		fill_below_window;
+#endif
+    linenr_T	old_botline = curwin->w_botline;
+    linenr_T	old_valid = curwin->w_valid;
+    int		old_empty_rows = curwin->w_empty_rows;
+    linenr_T	cln;		    // Cursor Line Number
+    long	so = get_scrolloff_value();
+    int		do_sms = curwin->w_p_wrap && curwin->w_p_sms;
+
+    cln = curwin->w_cursor.lnum;
+    if (set_topbot)
+    {
+	int set_skipcol = FALSE;
+
+	used = 0;
+	curwin->w_botline = cln + 1;
+#ifdef FEAT_DIFF
+	loff.fill = 0;
+#endif
+	for (curwin->w_topline = curwin->w_botline;
+		curwin->w_topline > 1;
+		curwin->w_topline = loff.lnum)
+	{
+	    loff.lnum = curwin->w_topline;
+	    topline_back_winheight(&loff, FALSE);
+	    if (loff.height == MAXCOL)
+		break;
+	    if (used + loff.height > curwin->w_height)
+	    {
+		if (do_sms)
+		{
+		    // 'smoothscroll' and 'wrap' are set.  The above line is
+		    // too long to show in its entirety, so we show just a part
+		    // of it.
+		    if (used < curwin->w_height)
+		    {
+			int plines_offset = used + loff.height
+							    - curwin->w_height;
+			used = curwin->w_height;
+#ifdef FEAT_DIFF
+			curwin->w_topfill = loff.fill;
+#endif
+			curwin->w_topline = loff.lnum;
+			curwin->w_skipcol = skipcol_from_plines(
+							curwin, plines_offset);
+			set_skipcol = TRUE;
+		    }
+		}
+		break;
+	    }
+	    used += loff.height;
+#ifdef FEAT_DIFF
+	    curwin->w_topfill = loff.fill;
+#endif
+	}
+	set_empty_rows(curwin, used);
+	curwin->w_valid |= VALID_BOTLINE|VALID_BOTLINE_AP;
+	if (curwin->w_topline != old_topline
+#ifdef FEAT_DIFF
+		|| curwin->w_topfill != old_topfill
+#endif
+		|| set_skipcol
+		|| curwin->w_skipcol != 0)
+	{
+	    curwin->w_valid &= ~(VALID_WROW|VALID_CROW);
+	    if (set_skipcol)
+		redraw_later(UPD_NOT_VALID);
+	    else
+		reset_skipcol();
+	}
+    }
+    else
+	validate_botline();
+
+    // The lines of the cursor line itself are always used.
+#ifdef FEAT_DIFF
+    used = plines_nofill(cln);
+#else
+    validate_cheight();
+    used = curwin->w_cline_height;
+#endif
+
+    // If the cursor is on or below botline, we will at least scroll by the
+    // height of the cursor line, which is "used".  Correct for empty lines,
+    // which are really part of botline.
+    if (cln >= curwin->w_botline)
+    {
+	scrolled = used;
+	if (cln == curwin->w_botline)
+	    scrolled -= curwin->w_empty_rows;
+	if (do_sms)
+	{
+	    // 'smoothscroll' and 'wrap' are set.
+	    // Calculate how many screen lines the current top line of window
+	    // occupies. If it is occupying more than the entire window, we
+	    // need to scroll the additional clipped lines to scroll past the
+	    // top line before we can move on to the other lines.
+	    int top_plines =
+#ifdef FEAT_DIFF
+			    plines_win_nofill
+#else
+			    plines_win
+#endif
+					(curwin, curwin->w_topline, FALSE);
+	    int skip_lines = 0;
+	    int width1 = curwin->w_width - curwin_col_off();
+	    if (width1 > 0)
+	    {
+		int width2 = width1 + curwin_col_off2();
+		// similar formula is used in curs_columns()
+		if (curwin->w_skipcol > width1)
+		    skip_lines += (curwin->w_skipcol - width1) / width2 + 1;
+		else if (curwin->w_skipcol > 0)
+		    skip_lines = 1;
+
+		top_plines -= skip_lines;
+		if (top_plines > curwin->w_height)
+		{
+		    scrolled += (top_plines - curwin->w_height);
+		}
+	    }
+	}
+    }
+
+    /*
+     * Stop counting lines to scroll when
+     * - hitting start of the file
+     * - scrolled nothing or at least 'sj' lines
+     * - at least 'scrolloff' lines below the cursor
+     * - lines between botline and cursor have been counted
+     */
+#ifdef FEAT_FOLDING
+    if (!hasFolding(curwin->w_cursor.lnum, &loff.lnum, &boff.lnum))
+#endif
+    {
+	loff.lnum = cln;
+	boff.lnum = cln;
+    }
+#ifdef FEAT_DIFF
+    loff.fill = 0;
+    boff.fill = 0;
+    fill_below_window = diff_check_fill(curwin, curwin->w_botline)
+						      - curwin->w_filler_rows;
+#endif
+
+    while (loff.lnum > 1)
+    {
+	// Stop when scrolled nothing or at least "min_scroll", found "extra"
+	// context for 'scrolloff' and counted all lines below the window.
+	if ((((scrolled <= 0 || scrolled >= min_scroll)
+		    && extra >= (mouse_dragging > 0 ? mouse_dragging - 1 : so))
+		    || boff.lnum + 1 > curbuf->b_ml.ml_line_count)
+		&& loff.lnum <= curwin->w_botline
+#ifdef FEAT_DIFF
+		&& (loff.lnum < curwin->w_botline
+		    || loff.fill >= fill_below_window)
+#endif
+		)
+	    break;
+
+	// Add one line above
+	topline_back(&loff);
+	if (loff.height == MAXCOL)
+	    used = MAXCOL;
+	else
+	    used += loff.height;
+	if (used > curwin->w_height)
+	    break;
+	if (loff.lnum >= curwin->w_botline
+#ifdef FEAT_DIFF
+		&& (loff.lnum > curwin->w_botline
+		    || loff.fill <= fill_below_window)
+#endif
+		)
+	{
+	    // Count screen lines that are below the window.
+	    scrolled += loff.height;
+	    if (loff.lnum == curwin->w_botline
+#ifdef FEAT_DIFF
+			    && loff.fill == 0
+#endif
+		    )
+		scrolled -= curwin->w_empty_rows;
+	}
+
+	if (boff.lnum < curbuf->b_ml.ml_line_count)
+	{
+	    // Add one line below
+	    botline_forw(&boff);
+	    used += boff.height;
+	    if (used > curwin->w_height)
+		break;
+	    if (extra < ( mouse_dragging > 0 ? mouse_dragging - 1 : so)
+		    || scrolled < min_scroll)
+	    {
+		extra += boff.height;
+		if (boff.lnum >= curwin->w_botline
+#ifdef FEAT_DIFF
+			|| (boff.lnum + 1 == curwin->w_botline
+			    && boff.fill > curwin->w_filler_rows)
+#endif
+		   )
+		{
+		    // Count screen lines that are below the window.
+		    scrolled += boff.height;
+		    if (boff.lnum == curwin->w_botline
+#ifdef FEAT_DIFF
+			    && boff.fill == 0
+#endif
+			    )
+			scrolled -= curwin->w_empty_rows;
+		}
+	    }
+	}
+    }
+
+    // curwin->w_empty_rows is larger, no need to scroll
+    if (scrolled <= 0)
+	line_count = 0;
+    // more than a screenfull, don't scroll but redraw
+    else if (used > curwin->w_height)
+	line_count = used;
+    // scroll minimal number of lines
+    else
+    {
+	line_count = 0;
+#ifdef FEAT_DIFF
+	boff.fill = curwin->w_topfill;
+#endif
+	boff.lnum = curwin->w_topline - 1;
+	for (i = 0; i < scrolled && boff.lnum < curwin->w_botline; )
+	{
+	    botline_forw(&boff);
+	    i += boff.height;
+	    ++line_count;
+	}
+	if (i < scrolled)	// below curwin->w_botline, don't scroll
+	    line_count = 9999;
+    }
+
+    /*
+     * Scroll up if the cursor is off the bottom of the screen a bit.
+     * Otherwise put it at 1/2 of the screen.
+     */
+    if (line_count >= curwin->w_height && line_count > min_scroll)
+	scroll_cursor_halfway(FALSE, TRUE);
+    else if (line_count > 0)
+    {
+	if (do_sms)
+	    scrollup(scrolled, TRUE);  // TODO
+	else
+	    scrollup(line_count, TRUE);
+    }
+
+    /*
+     * If topline didn't change we need to restore w_botline and w_empty_rows
+     * (we changed them).
+     * If topline did change, update_screen() will set botline.
+     */
+    if (curwin->w_topline == old_topline
+	    && curwin->w_skipcol == old_skipcol
+	    && set_topbot)
+    {
+	curwin->w_botline = old_botline;
+	curwin->w_empty_rows = old_empty_rows;
+	curwin->w_valid = old_valid;
+    }
+    curwin->w_valid |= VALID_TOPLINE;
+}
+
+/*
+ * Recompute topline to put the cursor halfway the window
+ * If "atend" is TRUE, also put it halfway at the end of the file.
+ */
+    void
+scroll_cursor_halfway(int atend, int prefer_above)
+{
+    int		above = 0;
+    linenr_T	topline;
+    colnr_T	skipcol = 0;
+#ifdef FEAT_DIFF
+    int		topfill = 0;
+#endif
+    int		below = 0;
+    int		used;
+    lineoff_T	loff;
+    lineoff_T	boff;
+#ifdef FEAT_DIFF
+    linenr_T	old_topline = curwin->w_topline;
+#endif
+
+#ifdef FEAT_PROP_POPUP
+    // if the width changed this needs to be updated first
+    may_update_popup_position();
+#endif
+    loff.lnum = boff.lnum = curwin->w_cursor.lnum;
+#ifdef FEAT_FOLDING
+    (void)hasFolding(loff.lnum, &loff.lnum, &boff.lnum);
+#endif
+#ifdef FEAT_DIFF
+    used = plines_nofill(loff.lnum);
+    loff.fill = 0;
+    boff.fill = 0;
+#else
+    used = plines(loff.lnum);
+#endif
+    topline = loff.lnum;
+
+    int want_height;
+    int do_sms = curwin->w_p_wrap && curwin->w_p_sms;
+    if (do_sms)
+    {
+	// 'smoothscroll' and 'wrap' are set
+	if (atend)
+	{
+	    want_height = (curwin->w_height - used) / 2;
+	    used = 0;
+	}
+	else
+	    want_height = curwin->w_height;
+    }
+
+    while (topline > 1)
+    {
+	// If using smoothscroll, we can precisely scroll to the
+	// exact point where the cursor is halfway down the screen.
+	if (do_sms)
+	{
+	    topline_back_winheight(&loff, FALSE);
+	    if (loff.height == MAXCOL)
+		break;
+	    used += loff.height;
+	    if (!atend && boff.lnum < curbuf->b_ml.ml_line_count)
+	    {
+		botline_forw(&boff);
+		used += boff.height;
+	    }
+	    if (used > want_height)
+	    {
+		if (used - loff.height < want_height)
+		{
+		    topline = loff.lnum;
+#ifdef FEAT_DIFF
+		    topfill = loff.fill;
+#endif
+		    skipcol = skipcol_from_plines(curwin, used - want_height);
+		}
+		break;
+	    }
+	    topline = loff.lnum;
+#ifdef FEAT_DIFF
+	    topfill = loff.fill;
+#endif
+	    continue;
+	}
+
+	// If not using smoothscroll, we have to iteratively find how many
+	// lines to scroll down to roughly fit the cursor.
+	// This may not be right in the middle if the lines'
+	// physical height > 1 (e.g. 'wrap' is on).
+
+	// Depending on "prefer_above" we add a line above or below first.
+	// Loop twice to avoid duplicating code.
+	int done = FALSE;
+	for (int round = 1; round <= 2; ++round)
+	{
+	    if (prefer_above ? (round == 2 && below < above)
+			     : (round == 1 && below <= above))
+	    {
+		// add a line below the cursor
+		if (boff.lnum < curbuf->b_ml.ml_line_count)
+		{
+		    botline_forw(&boff);
+		    used += boff.height;
+		    if (used > curwin->w_height)
+		    {
+			done = TRUE;
+			break;
+		    }
+		    below += boff.height;
+		}
+		else
+		{
+		    ++below;	    // count a "~" line
+		    if (atend)
+			++used;
+		}
+	    }
+
+	    if (prefer_above ? (round == 1 && below >= above)
+			     : (round == 1 && below > above))
+	    {
+		// add a line above the cursor
+		topline_back(&loff);
+		if (loff.height == MAXCOL)
+		    used = MAXCOL;
+		else
+		    used += loff.height;
+		if (used > curwin->w_height)
+		{
+		    done = TRUE;
+		    break;
+		}
+		above += loff.height;
+		topline = loff.lnum;
+#ifdef FEAT_DIFF
+		topfill = loff.fill;
+#endif
+	    }
+	}
+	if (done)
+	    break;
+    }
+
+#ifdef FEAT_FOLDING
+    if (!hasFolding(topline, &curwin->w_topline, NULL))
+#endif
+    {
+	if (curwin->w_topline != topline
+		|| skipcol != 0
+		|| curwin->w_skipcol != 0)
+	{
+	    curwin->w_topline = topline;
+	    if (skipcol != 0)
+	    {
+		curwin->w_skipcol = skipcol;
+		redraw_later(UPD_NOT_VALID);
+	    }
+	    else if (do_sms)
+		reset_skipcol();
+	}
+    }
+#ifdef FEAT_DIFF
+    curwin->w_topfill = topfill;
+    if (old_topline > curwin->w_topline + curwin->w_height)
+	curwin->w_botfill = FALSE;
+    check_topfill(curwin, FALSE);
+#endif
+    curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
+    curwin->w_valid |= VALID_TOPLINE;
+}
+
+/*
+ * Correct the cursor position so that it is in a part of the screen at least
+ * 'scrolloff' lines from the top and bottom, if possible.
+ * If not possible, put it at the same position as scroll_cursor_halfway().
+ * When called topline must be valid!
+ */
+    void
+cursor_correct(void)
+{
+    int		above = 0;	    // screen lines above topline
+    linenr_T	topline;
+    int		below = 0;	    // screen lines below botline
+    linenr_T	botline;
+    int		above_wanted, below_wanted;
+    linenr_T	cln;		    // Cursor Line Number
+    int		max_off;
+    long	so = get_scrolloff_value();
+
+    /*
+     * How many lines we would like to have above/below the cursor depends on
+     * whether the first/last line of the file is on screen.
+     */
+    above_wanted = so;
+    below_wanted = so;
+    if (mouse_dragging > 0)
+    {
+	above_wanted = mouse_dragging - 1;
+	below_wanted = mouse_dragging - 1;
+    }
+    if (curwin->w_topline == 1)
+    {
+	above_wanted = 0;
+	max_off = curwin->w_height / 2;
+	if (below_wanted > max_off)
+	    below_wanted = max_off;
+    }
+    validate_botline();
+    if (curwin->w_botline == curbuf->b_ml.ml_line_count + 1
+	    && mouse_dragging == 0)
+    {
+	below_wanted = 0;
+	max_off = (curwin->w_height - 1) / 2;
+	if (above_wanted > max_off)
+	    above_wanted = max_off;
+    }
+
+    /*
+     * If there are sufficient file-lines above and below the cursor, we can
+     * return now.
+     */
+    cln = curwin->w_cursor.lnum;
+    if (cln >= curwin->w_topline + above_wanted
+	    && cln < curwin->w_botline - below_wanted
+#ifdef FEAT_FOLDING
+	    && !hasAnyFolding(curwin)
+#endif
+	    )
+	return;
+
+    if (curwin->w_p_sms && !curwin->w_p_wrap)
+    {
+	// 'smoothscroll' is active
+	if (curwin->w_cline_height == curwin->w_height)
+	{
+	    // The cursor line just fits in the window, don't scroll.
+	    reset_skipcol();
+	    return;
+	}
+	// TODO: If the cursor line doesn't fit in the window then only adjust
+	// w_skipcol.
+    }
+
+    /*
+     * Narrow down the area where the cursor can be put by taking lines from
+     * the top and the bottom until:
+     * - the desired context lines are found
+     * - the lines from the top is past the lines from the bottom
+     */
+    topline = curwin->w_topline;
+    botline = curwin->w_botline - 1;
+#ifdef FEAT_DIFF
+    // count filler lines as context
+    above = curwin->w_topfill;
+    below = curwin->w_filler_rows;
+#endif
+    while ((above < above_wanted || below < below_wanted) && topline < botline)
+    {
+	if (below < below_wanted && (below <= above || above >= above_wanted))
+	{
+#ifdef FEAT_FOLDING
+	    if (hasFolding(botline, &botline, NULL))
+		++below;
+	    else
+#endif
+		below += plines(botline);
+	    --botline;
+	}
+	if (above < above_wanted && (above < below || below >= below_wanted))
+	{
+#ifdef FEAT_FOLDING
+	    if (hasFolding(topline, NULL, &topline))
+		++above;
+	    else
+#endif
+		above += PLINES_NOFILL(topline);
+#ifdef FEAT_DIFF
+	    // Count filler lines below this line as context.
+	    if (topline < botline)
+		above += diff_check_fill(curwin, topline + 1);
+#endif
+	    ++topline;
+	}
+    }
+    if (topline == botline || botline == 0)
+	curwin->w_cursor.lnum = topline;
+    else if (topline > botline)
+	curwin->w_cursor.lnum = botline;
+    else
+    {
+	if (cln < topline && curwin->w_topline > 1)
+	{
+	    curwin->w_cursor.lnum = topline;
+	    curwin->w_valid &=
+			    ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW);
+	}
+	if (cln > botline && curwin->w_botline <= curbuf->b_ml.ml_line_count)
+	{
+	    curwin->w_cursor.lnum = botline;
+	    curwin->w_valid &=
+			    ~(VALID_WROW|VALID_WCOL|VALID_CHEIGHT|VALID_CROW);
+	}
+    }
+    curwin->w_valid |= VALID_TOPLINE;
+}
+
+static void get_scroll_overlap(lineoff_T *lp, int dir);
+
+/*
+ * Move screen "count" pages up ("dir" is BACKWARD) or down ("dir" is FORWARD)
+ * and update the screen.
+ *
+ * Return FAIL for failure, OK otherwise.
+ */
+    int
+onepage(int dir, long count)
+{
+    long	n;
+    int		retval = OK;
+    lineoff_T	loff;
+    linenr_T	old_topline = curwin->w_topline;
+    long	so = get_scrolloff_value();
+
+    if (curbuf->b_ml.ml_line_count == 1)    // nothing to do
+    {
+	beep_flush();
+	return FAIL;
+    }
+
+    for ( ; count > 0; --count)
+    {
+	validate_botline();
+	/*
+	 * It's an error to move a page up when the first line is already on
+	 * the screen.	It's an error to move a page down when the last line
+	 * is on the screen and the topline is 'scrolloff' lines from the
+	 * last line.
+	 */
+	if (dir == FORWARD
+		? ((curwin->w_topline >= curbuf->b_ml.ml_line_count - so)
+		    && curwin->w_botline > curbuf->b_ml.ml_line_count)
+		: (curwin->w_topline == 1
+#ifdef FEAT_DIFF
+		    && curwin->w_topfill ==
+				    diff_check_fill(curwin, curwin->w_topline)
+#endif
+		    ))
+	{
+	    beep_flush();
+	    retval = FAIL;
+	    break;
+	}
+
+#ifdef FEAT_DIFF
+	loff.fill = 0;
+#endif
+	if (dir == FORWARD)
+	{
+	    if (ONE_WINDOW && p_window > 0 && p_window < Rows - 1)
+	    {
+		// Vi compatible scrolling
+		if (p_window <= 2)
+		    ++curwin->w_topline;
+		else
+		    curwin->w_topline += p_window - 2;
+		if (curwin->w_topline > curbuf->b_ml.ml_line_count)
+		    curwin->w_topline = curbuf->b_ml.ml_line_count;
+		curwin->w_cursor.lnum = curwin->w_topline;
+	    }
+	    else if (curwin->w_botline > curbuf->b_ml.ml_line_count)
+	    {
+		// at end of file
+		curwin->w_topline = curbuf->b_ml.ml_line_count;
+#ifdef FEAT_DIFF
+		curwin->w_topfill = 0;
+#endif
+		curwin->w_valid &= ~(VALID_WROW|VALID_CROW);
+	    }
+	    else
+	    {
+		// For the overlap, start with the line just below the window
+		// and go upwards.
+		loff.lnum = curwin->w_botline;
+#ifdef FEAT_DIFF
+		loff.fill = diff_check_fill(curwin, loff.lnum)
+						      - curwin->w_filler_rows;
+#endif
+		get_scroll_overlap(&loff, -1);
+		curwin->w_topline = loff.lnum;
+#ifdef FEAT_DIFF
+		curwin->w_topfill = loff.fill;
+		check_topfill(curwin, FALSE);
+#endif
+		curwin->w_cursor.lnum = curwin->w_topline;
+		curwin->w_valid &= ~(VALID_WCOL|VALID_CHEIGHT|VALID_WROW|
+				   VALID_CROW|VALID_BOTLINE|VALID_BOTLINE_AP);
+	    }
+	}
+	else	// dir == BACKWARDS
+	{
+#ifdef FEAT_DIFF
+	    if (curwin->w_topline == 1)
+	    {
+		// Include max number of filler lines
+		max_topfill();
+		continue;
+	    }
+#endif
+	    if (ONE_WINDOW && p_window > 0 && p_window < Rows - 1)
+	    {
+		// Vi compatible scrolling (sort of)
+		if (p_window <= 2)
+		    --curwin->w_topline;
+		else
+		    curwin->w_topline -= p_window - 2;
+		if (curwin->w_topline < 1)
+		    curwin->w_topline = 1;
+		curwin->w_cursor.lnum = curwin->w_topline + p_window - 1;
+		if (curwin->w_cursor.lnum > curbuf->b_ml.ml_line_count)
+		    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
+		continue;
+	    }
+
+	    // Find the line at the top of the window that is going to be the
+	    // line at the bottom of the window.  Make sure this results in
+	    // the same line as before doing CTRL-F.
+	    loff.lnum = curwin->w_topline - 1;
+#ifdef FEAT_DIFF
+	    loff.fill = diff_check_fill(curwin, loff.lnum + 1)
+							  - curwin->w_topfill;
+#endif
+	    get_scroll_overlap(&loff, 1);
+
+	    if (loff.lnum >= curbuf->b_ml.ml_line_count)
+	    {
+		loff.lnum = curbuf->b_ml.ml_line_count;
+#ifdef FEAT_DIFF
+		loff.fill = 0;
+	    }
+	    else
+	    {
+		botline_topline(&loff);
+#endif
+	    }
+	    curwin->w_cursor.lnum = loff.lnum;
+
+	    // Find the line just above the new topline to get the right line
+	    // at the bottom of the window.
+	    n = 0;
+	    while (n <= curwin->w_height && loff.lnum >= 1)
+	    {
+		topline_back(&loff);
+		if (loff.height == MAXCOL)
+		    n = MAXCOL;
+		else
+		    n += loff.height;
+	    }
+	    if (loff.lnum < 1)			// at begin of file
+	    {
+		curwin->w_topline = 1;
+#ifdef FEAT_DIFF
+		max_topfill();
+#endif
+		curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
+	    }
+	    else
+	    {
+		// Go two lines forward again.
+#ifdef FEAT_DIFF
+		topline_botline(&loff);
+#endif
+		botline_forw(&loff);
+		botline_forw(&loff);
+#ifdef FEAT_DIFF
+		botline_topline(&loff);
+#endif
+#ifdef FEAT_FOLDING
+		// We're at the wrong end of a fold now.
+		(void)hasFolding(loff.lnum, &loff.lnum, NULL);
+#endif
+
+		// Always scroll at least one line.  Avoid getting stuck on
+		// very long lines.
+		if (loff.lnum >= curwin->w_topline
+#ifdef FEAT_DIFF
+			&& (loff.lnum > curwin->w_topline
+			    || loff.fill >= curwin->w_topfill)
+#endif
+			)
+		{
+#ifdef FEAT_DIFF
+		    // First try using the maximum number of filler lines.  If
+		    // that's not enough, backup one line.
+		    loff.fill = curwin->w_topfill;
+		    if (curwin->w_topfill < diff_check_fill(curwin,
+							   curwin->w_topline))
+			max_topfill();
+		    if (curwin->w_topfill == loff.fill)
+#endif
+		    {
+			--curwin->w_topline;
+#ifdef FEAT_DIFF
+			curwin->w_topfill = 0;
+#endif
+		    }
+		    comp_botline(curwin);
+		    curwin->w_cursor.lnum = curwin->w_botline - 1;
+		    curwin->w_valid &=
+			    ~(VALID_WCOL|VALID_CHEIGHT|VALID_WROW|VALID_CROW);
+		}
+		else
+		{
+		    curwin->w_topline = loff.lnum;
+#ifdef FEAT_DIFF
+		    curwin->w_topfill = loff.fill;
+		    check_topfill(curwin, FALSE);
+#endif
+		    curwin->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
+		}
+	    }
+	}
+    }
+#ifdef FEAT_FOLDING
+    foldAdjustCursor();
+#endif
+    cursor_correct();
+    check_cursor_col();
+    if (retval == OK)
+	beginline(BL_SOL | BL_FIX);
+    curwin->w_valid &= ~(VALID_WCOL|VALID_WROW|VALID_VIRTCOL);
+
+    if (retval == OK && dir == FORWARD)
+    {
+	// Avoid the screen jumping up and down when 'scrolloff' is non-zero.
+	// But make sure we scroll at least one line (happens with mix of long
+	// wrapping lines and non-wrapping line).
+	if (check_top_offset())
+	{
+	    scroll_cursor_top(1, FALSE);
+	    if (curwin->w_topline <= old_topline
+				  && old_topline < curbuf->b_ml.ml_line_count)
+	    {
+		curwin->w_topline = old_topline + 1;
+#ifdef FEAT_FOLDING
+		(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+	    }
+	}
+#ifdef FEAT_FOLDING
+	else if (curwin->w_botline > curbuf->b_ml.ml_line_count)
+	    (void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+    }
+
+    redraw_later(UPD_VALID);
+    return retval;
+}
+
+/*
+ * Decide how much overlap to use for page-up or page-down scrolling.
+ * This is symmetric, so that doing both keeps the same lines displayed.
+ * Three lines are examined:
+ *
+ *  before CTRL-F	    after CTRL-F / before CTRL-B
+ *     etc.			l1
+ *  l1 last but one line	------------
+ *  l2 last text line		l2 top text line
+ *  -------------		l3 second text line
+ *  l3				   etc.
+ */
+    static void
+get_scroll_overlap(lineoff_T *lp, int dir)
+{
+    int		h1, h2, h3, h4;
+    int		min_height = curwin->w_height - 2;
+    lineoff_T	loff0, loff1, loff2;
+
+#ifdef FEAT_DIFF
+    if (lp->fill > 0)
+	lp->height = 1;
+    else
+	lp->height = plines_nofill(lp->lnum);
+#else
+    lp->height = plines(lp->lnum);
+#endif
+    h1 = lp->height;
+    if (h1 > min_height)
+	return;		// no overlap
+
+    loff0 = *lp;
+    if (dir > 0)
+	botline_forw(lp);
+    else
+	topline_back(lp);
+    h2 = lp->height;
+    if (h2 == MAXCOL || h2 + h1 > min_height)
+    {
+	*lp = loff0;	// no overlap
+	return;
+    }
+
+    loff1 = *lp;
+    if (dir > 0)
+	botline_forw(lp);
+    else
+	topline_back(lp);
+    h3 = lp->height;
+    if (h3 == MAXCOL || h3 + h2 > min_height)
+    {
+	*lp = loff0;	// no overlap
+	return;
+    }
+
+    loff2 = *lp;
+    if (dir > 0)
+	botline_forw(lp);
+    else
+	topline_back(lp);
+    h4 = lp->height;
+    if (h4 == MAXCOL || h4 + h3 + h2 > min_height || h3 + h2 + h1 > min_height)
+	*lp = loff1;	// 1 line overlap
+    else
+	*lp = loff2;	// 2 lines overlap
+}
+
+/*
+ * Scroll 'scroll' lines up or down.
+ */
+    void
+halfpage(int flag, linenr_T Prenum)
+{
+    long	scrolled = 0;
+    int		i;
+    int		n;
+    int		room;
+
+    if (Prenum)
+	curwin->w_p_scr = (Prenum > curwin->w_height) ?
+						curwin->w_height : Prenum;
+    n = (curwin->w_p_scr <= curwin->w_height) ?
+				    curwin->w_p_scr : curwin->w_height;
+
+    update_topline();
+    validate_botline();
+    room = curwin->w_empty_rows;
+#ifdef FEAT_DIFF
+    room += curwin->w_filler_rows;
+#endif
+    if (flag)
+    {
+	/*
+	 * scroll the text up
+	 */
+	while (n > 0 && curwin->w_botline <= curbuf->b_ml.ml_line_count)
+	{
+#ifdef FEAT_DIFF
+	    if (curwin->w_topfill > 0)
+	    {
+		i = 1;
+		--n;
+		--curwin->w_topfill;
+	    }
+	    else
+#endif
+	    {
+		i = PLINES_NOFILL(curwin->w_topline);
+		n -= i;
+		if (n < 0 && scrolled > 0)
+		    break;
+#ifdef FEAT_FOLDING
+		(void)hasFolding(curwin->w_topline, NULL, &curwin->w_topline);
+#endif
+		++curwin->w_topline;
+#ifdef FEAT_DIFF
+		curwin->w_topfill = diff_check_fill(curwin, curwin->w_topline);
+#endif
+
+		if (curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
+		{
+		    ++curwin->w_cursor.lnum;
+		    curwin->w_valid &=
+				    ~(VALID_VIRTCOL|VALID_CHEIGHT|VALID_WCOL);
+		}
+	    }
+	    curwin->w_valid &= ~(VALID_CROW|VALID_WROW);
+	    scrolled += i;
+
+	    /*
+	     * Correct w_botline for changed w_topline.
+	     * Won't work when there are filler lines.
+	     */
+#ifdef FEAT_DIFF
+	    if (curwin->w_p_diff)
+		curwin->w_valid &= ~(VALID_BOTLINE|VALID_BOTLINE_AP);
+	    else
+#endif
+	    {
+		room += i;
+		do
+		{
+		    i = plines(curwin->w_botline);
+		    if (i > room)
+			break;
+#ifdef FEAT_FOLDING
+		    (void)hasFolding(curwin->w_botline, NULL,
+							  &curwin->w_botline);
+#endif
+		    ++curwin->w_botline;
+		    room -= i;
+		} while (curwin->w_botline <= curbuf->b_ml.ml_line_count);
+	    }
+	}
+
+	/*
+	 * When hit bottom of the file: move cursor down.
+	 */
+	if (n > 0)
+	{
+# ifdef FEAT_FOLDING
+	    if (hasAnyFolding(curwin))
+	    {
+		while (--n >= 0
+			&& curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
+		{
+		    (void)hasFolding(curwin->w_cursor.lnum, NULL,
+						      &curwin->w_cursor.lnum);
+		    ++curwin->w_cursor.lnum;
+		}
+	    }
+	    else
+# endif
+		curwin->w_cursor.lnum += n;
+	    check_cursor_lnum();
+	}
+    }
+    else
+    {
+	/*
+	 * scroll the text down
+	 */
+	while (n > 0 && curwin->w_topline > 1)
+	{
+#ifdef FEAT_DIFF
+	    if (curwin->w_topfill < diff_check_fill(curwin, curwin->w_topline))
+	    {
+		i = 1;
+		--n;
+		++curwin->w_topfill;
+	    }
+	    else
+#endif
+	    {
+		i = PLINES_NOFILL(curwin->w_topline - 1);
+		n -= i;
+		if (n < 0 && scrolled > 0)
+		    break;
+		--curwin->w_topline;
+#ifdef FEAT_FOLDING
+		(void)hasFolding(curwin->w_topline, &curwin->w_topline, NULL);
+#endif
+#ifdef FEAT_DIFF
+		curwin->w_topfill = 0;
+#endif
+	    }
+	    curwin->w_valid &= ~(VALID_CROW|VALID_WROW|
+					      VALID_BOTLINE|VALID_BOTLINE_AP);
+	    scrolled += i;
+	    if (curwin->w_cursor.lnum > 1)
+	    {
+		--curwin->w_cursor.lnum;
+		curwin->w_valid &= ~(VALID_VIRTCOL|VALID_CHEIGHT|VALID_WCOL);
+	    }
+	}
+
+	/*
+	 * When hit top of the file: move cursor up.
+	 */
+	if (n > 0)
+	{
+	    if (curwin->w_cursor.lnum <= (linenr_T)n)
+		curwin->w_cursor.lnum = 1;
+	    else
+# ifdef FEAT_FOLDING
+	    if (hasAnyFolding(curwin))
+	    {
+		while (--n >= 0 && curwin->w_cursor.lnum > 1)
+		{
+		    --curwin->w_cursor.lnum;
+		    (void)hasFolding(curwin->w_cursor.lnum,
+						&curwin->w_cursor.lnum, NULL);
+		}
+	    }
+	    else
+# endif
+		curwin->w_cursor.lnum -= n;
+	}
+    }
+# ifdef FEAT_FOLDING
+    // Move cursor to first line of closed fold.
+    foldAdjustCursor();
+# endif
+#ifdef FEAT_DIFF
+    check_topfill(curwin, !flag);
+#endif
+    cursor_correct();
+    beginline(BL_SOL | BL_FIX);
+    redraw_later(UPD_VALID);
+}
+
+    void
+do_check_cursorbind(void)
+{
+    linenr_T	line = curwin->w_cursor.lnum;
+    colnr_T	col = curwin->w_cursor.col;
+    colnr_T	coladd = curwin->w_cursor.coladd;
+    colnr_T	curswant = curwin->w_curswant;
+    int		set_curswant = curwin->w_set_curswant;
+    win_T	*old_curwin = curwin;
+    buf_T	*old_curbuf = curbuf;
+    int		old_VIsual_select = VIsual_select;
+    int		old_VIsual_active = VIsual_active;
+
+    /*
+     * loop through the cursorbound windows
+     */
+    VIsual_select = VIsual_active = 0;
+    FOR_ALL_WINDOWS(curwin)
+    {
+	curbuf = curwin->w_buffer;
+	// skip original window  and windows with 'noscrollbind'
+	if (curwin != old_curwin && curwin->w_p_crb)
+	{
+# ifdef FEAT_DIFF
+	    if (curwin->w_p_diff)
+		curwin->w_cursor.lnum =
+				 diff_get_corresponding_line(old_curbuf, line);
+	    else
+# endif
+		curwin->w_cursor.lnum = line;
+	    curwin->w_cursor.col = col;
+	    curwin->w_cursor.coladd = coladd;
+	    curwin->w_curswant = curswant;
+	    curwin->w_set_curswant = set_curswant;
+
+	    // Make sure the cursor is in a valid position.  Temporarily set
+	    // "restart_edit" to allow the cursor to be beyond the EOL.
+	    int restart_edit_save = restart_edit;
+	    restart_edit = 'a';
+	    check_cursor();
+
+	    // Avoid a scroll here for the cursor position, 'scrollbind' is
+	    // more important.
+	    if (!curwin->w_p_scb)
+		validate_cursor();
+
+	    restart_edit = restart_edit_save;
+	    // Correct cursor for multi-byte character.
+	    if (has_mbyte)
+		mb_adjust_cursor();
+	    redraw_later(UPD_VALID);
+
+	    // Only scroll when 'scrollbind' hasn't done this.
+	    if (!curwin->w_p_scb)
+		update_topline();
+	    curwin->w_redr_status = TRUE;
+	}
+    }
+
+    /*
+     * reset current-window
+     */
+    VIsual_select = old_VIsual_select;
+    VIsual_active = old_VIsual_active;
+    curwin = old_curwin;
+    curbuf = old_curbuf;
+}