/*
 * 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.
 */

/*
 * screen.c: code for displaying on the screen
 *
 * Output to the screen (console, terminal emulator or GUI window) is minimized
 * by remembering what is already on the screen, and only updating the parts
 * that changed.
 *
 * ScreenLines[off]  Contains a copy of the whole screen, as it is currently
 *		     displayed (excluding text written by external commands).
 * ScreenAttrs[off]  Contains the associated attributes.
 * LineOffset[row]   Contains the offset into ScreenLines*[] and ScreenAttrs[]
 *		     for each line.
 * LineWraps[row]    Flag for each line whether it wraps to the next line.
 *
 * For double-byte characters, two consecutive bytes in ScreenLines[] can form
 * one character which occupies two display cells.
 * For UTF-8 a multi-byte character is converted to Unicode and stored in
 * ScreenLinesUC[].  ScreenLines[] contains the first byte only.  For an ASCII
 * character without composing chars ScreenLinesUC[] will be 0 and
 * ScreenLinesC[][] is not used.  When the character occupies two display
 * cells the next byte in ScreenLines[] is 0.
 * ScreenLinesC[][] contain up to 'maxcombine' composing characters
 * (drawn on top of the first character).  There is 0 after the last one used.
 * ScreenLines2[] is only used for euc-jp to store the second byte if the
 * first byte is 0x8e (single-width character).
 *
 * The screen_*() functions write to the screen and handle updating
 * ScreenLines[].
 *
 * update_screen() is the function that updates all windows and status lines.
 * It is called form the main loop when must_redraw is non-zero.  It may be
 * called from other places when an immediate screen update is needed.
 *
 * The part of the buffer that is displayed in a window is set with:
 * - w_topline (first buffer line in window)
 * - w_topfill (filler lines above the first line)
 * - w_leftcol (leftmost window cell in window),
 * - w_skipcol (skipped window cells of first line)
 *
 * Commands that only move the cursor around in a window, do not need to take
 * action to update the display.  The main loop will check if w_topline is
 * valid and update it (scroll the window) when needed.
 *
 * Commands that scroll a window change w_topline and must call
 * check_cursor() to move the cursor into the visible part of the window, and
 * call redraw_later(VALID) to have the window displayed by update_screen()
 * later.
 *
 * Commands that change text in the buffer must call changed_bytes() or
 * changed_lines() to mark the area that changed and will require updating
 * later.  The main loop will call update_screen(), which will update each
 * window that shows the changed buffer.  This assumes text above the change
 * can remain displayed as it is.  Text after the change may need updating for
 * scrolling, folding and syntax highlighting.
 *
 * Commands that change how a window is displayed (e.g., setting 'list') or
 * invalidate the contents of a window in another way (e.g., change fold
 * settings), must call redraw_later(NOT_VALID) to have the whole window
 * redisplayed by update_screen() later.
 *
 * Commands that change how a buffer is displayed (e.g., setting 'tabstop')
 * must call redraw_curbuf_later(NOT_VALID) to have all the windows for the
 * buffer redisplayed by update_screen() later.
 *
 * Commands that change highlighting and possibly cause a scroll too must call
 * redraw_later(SOME_VALID) to update the whole window but still use scrolling
 * to avoid redrawing everything.  But the length of displayed lines must not
 * change, use NOT_VALID then.
 *
 * Commands that move the window position must call redraw_later(NOT_VALID).
 * TODO: should minimize redrawing by scrolling when possible.
 *
 * Commands that change everything (e.g., resizing the screen) must call
 * redraw_all_later(NOT_VALID) or redraw_all_later(CLEAR).
 *
 * Things that are handled indirectly:
 * - When messages scroll the screen up, msg_scrolled will be set and
 *   update_screen() called to redraw.
 */

#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdbool.h>
#include <string.h>

#include "nvim/vim.h"
#include "nvim/ascii.h"
#include "nvim/arabic.h"
#include "nvim/screen.h"
#include "nvim/buffer.h"
#include "nvim/charset.h"
#include "nvim/cursor.h"
#include "nvim/diff.h"
#include "nvim/eval.h"
#include "nvim/ex_cmds.h"
#include "nvim/ex_cmds2.h"
#include "nvim/ex_getln.h"
#include "nvim/edit.h"
#include "nvim/farsi.h"
#include "nvim/fileio.h"
#include "nvim/fold.h"
#include "nvim/indent.h"
#include "nvim/getchar.h"
#include "nvim/main.h"
#include "nvim/mbyte.h"
#include "nvim/memline.h"
#include "nvim/memory.h"
#include "nvim/menu.h"
#include "nvim/message.h"
#include "nvim/misc1.h"
#include "nvim/misc2.h"
#include "nvim/garray.h"
#include "nvim/move.h"
#include "nvim/normal.h"
#include "nvim/option.h"
#include "nvim/os_unix.h"
#include "nvim/path.h"
#include "nvim/popupmnu.h"
#include "nvim/quickfix.h"
#include "nvim/regexp.h"
#include "nvim/search.h"
#include "nvim/spell.h"
#include "nvim/strings.h"
#include "nvim/syntax.h"
#include "nvim/terminal.h"
#include "nvim/ui.h"
#include "nvim/undo.h"
#include "nvim/version.h"
#include "nvim/window.h"
#include "nvim/os/time.h"

#define MB_FILLER_CHAR '<'  /* character used when a double-width character
                             * doesn't fit. */
#define W_ENDCOL(wp)   (wp->w_wincol + wp->w_width)

/*
 * The attributes that are actually active for writing to the screen.
 */
static int screen_attr = 0;

static match_T search_hl;       /* used for 'hlsearch' highlight matching */

static foldinfo_T win_foldinfo; /* info for 'foldcolumn' */

/*
 * Buffer for one screen line (characters and attributes).
 */
static schar_T  *current_ScreenLine;

# define SCREEN_LINE(r, o, e, c, rl)    screen_line((r), (o), (e), (c), (rl))
#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "screen.c.generated.h"
#endif
#define SEARCH_HL_PRIORITY 0

//signs column

/* Ugly global: overrule attribute used by screen_char() */
static int screen_char_attr = 0;

/*
 * Redraw the current window later, with update_screen(type).
 * Set must_redraw only if not already set to a higher value.
 * e.g. if must_redraw is CLEAR, type NOT_VALID will do nothing.
 */
void redraw_later(int type)
{
  redraw_win_later(curwin, type);
}

void redraw_win_later(win_T *wp, int type)
{
  if (wp->w_redr_type < type) {
    wp->w_redr_type = type;
    if (type >= NOT_VALID)
      wp->w_lines_valid = 0;
    if (must_redraw < type)     /* must_redraw is the maximum of all windows */
      must_redraw = type;
  }
}

/*
 * Force a complete redraw later.  Also resets the highlighting.  To be used
 * after executing a shell command that messes up the screen.
 */
void redraw_later_clear(void)
{
  redraw_all_later(CLEAR);
  /* Use attributes that is very unlikely to appear in text. */
  screen_attr = HL_BOLD | HL_UNDERLINE | HL_INVERSE;
}

/*
 * Mark all windows to be redrawn later.
 */
void redraw_all_later(int type)
{
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    redraw_win_later(wp, type);
  }
}

/*
 * Mark all windows that are editing the current buffer to be updated later.
 */
void redraw_curbuf_later(int type)
{
  redraw_buf_later(curbuf, type);
}

void redraw_buf_later(buf_T *buf, int type)
{
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    if (wp->w_buffer == buf) {
      redraw_win_later(wp, type);
    }
  }
}

/*
 * Changed something in the current window, at buffer line "lnum", that
 * requires that line and possibly other lines to be redrawn.
 * Used when entering/leaving Insert mode with the cursor on a folded line.
 * Used to remove the "$" from a change command.
 * Note that when also inserting/deleting lines w_redraw_top and w_redraw_bot
 * may become invalid and the whole window will have to be redrawn.
 */
void
redrawWinline (
    linenr_T lnum,
    int invalid             /* window line height is invalid now */
)
{
  int i;

  if (curwin->w_redraw_top == 0 || curwin->w_redraw_top > lnum)
    curwin->w_redraw_top = lnum;
  if (curwin->w_redraw_bot == 0 || curwin->w_redraw_bot < lnum)
    curwin->w_redraw_bot = lnum;
  redraw_later(VALID);

  if (invalid) {
    /* A w_lines[] entry for this lnum has become invalid. */
    i = find_wl_entry(curwin, lnum);
    if (i >= 0)
      curwin->w_lines[i].wl_valid = FALSE;
  }
}

/*
 * update all windows that are editing the current buffer
 */
void update_curbuf(int type)
{
  redraw_curbuf_later(type);
  update_screen(type);
}

/*
 * update_screen()
 *
 * Based on the current value of curwin->w_topline, transfer a screenfull
 * of stuff from Filemem to ScreenLines[], and update curwin->w_botline.
 */
void update_screen(int type)
{
  static int did_intro = FALSE;
  int did_one;

  /* Don't do anything if the screen structures are (not yet) valid. */
  if (!screen_valid(TRUE))
    return;

  if (must_redraw) {
    if (type < must_redraw)         /* use maximal type */
      type = must_redraw;

    /* must_redraw is reset here, so that when we run into some weird
    * reason to redraw while busy redrawing (e.g., asynchronous
    * scrolling), or update_topline() in win_update() will cause a
    * scroll, the screen will be redrawn later or in win_update(). */
    must_redraw = 0;
  }

  /* Need to update w_lines[]. */
  if (curwin->w_lines_valid == 0 && type < NOT_VALID)
    type = NOT_VALID;

  /* Postpone the redrawing when it's not needed and when being called
   * recursively. */
  if (!redrawing() || updating_screen) {
    redraw_later(type);                 /* remember type for next time */
    must_redraw = type;
    if (type > INVERTED_ALL)
      curwin->w_lines_valid = 0;        /* don't use w_lines[].wl_size now */
    return;
  }

  updating_screen = TRUE;
  ++display_tick;           /* let syntax code know we're in a next round of
                             * display updating */

  /*
   * if the screen was scrolled up when displaying a message, scroll it down
   */
  if (msg_scrolled) {
    clear_cmdline = TRUE;
    if (msg_scrolled > Rows - 5)            /* clearing is faster */
      type = CLEAR;
    else if (type != CLEAR) {
      check_for_delay(FALSE);
      if (screen_ins_lines(0, 0, msg_scrolled, (int)Rows, NULL) == FAIL)
        type = CLEAR;
      FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
        if (wp->w_winrow < msg_scrolled) {
          if (wp->w_winrow + wp->w_height > msg_scrolled
              && wp->w_redr_type < REDRAW_TOP
              && wp->w_lines_valid > 0
              && wp->w_topline == wp->w_lines[0].wl_lnum) {
            wp->w_upd_rows = msg_scrolled - wp->w_winrow;
            wp->w_redr_type = REDRAW_TOP;
          } else {
            wp->w_redr_type = NOT_VALID;
            if (wp->w_winrow + wp->w_height + wp->w_status_height
                <= msg_scrolled) {
              wp->w_redr_status = TRUE;
            }
          }
        }
      }
      redraw_cmdline = TRUE;
      redraw_tabline = TRUE;
    }
    msg_scrolled = 0;
    need_wait_return = FALSE;
  }

  /* reset cmdline_row now (may have been changed temporarily) */
  compute_cmdrow();

  /* Check for changed highlighting */
  if (need_highlight_changed)
    highlight_changed();

  if (type == CLEAR) {          /* first clear screen */
    screenclear();              /* will reset clear_cmdline */
    type = NOT_VALID;
  }

  if (clear_cmdline)            /* going to clear cmdline (done below) */
    check_for_delay(FALSE);

  /* Force redraw when width of 'number' or 'relativenumber' column
   * changes. */
  if (curwin->w_redr_type < NOT_VALID
      && curwin->w_nrwidth != ((curwin->w_p_nu || curwin->w_p_rnu)
                               ? number_width(curwin) : 0))
    curwin->w_redr_type = NOT_VALID;

  /*
   * Only start redrawing if there is really something to do.
   */
  if (type == INVERTED)
    update_curswant();
  if (curwin->w_redr_type < type
      && !((type == VALID
            && curwin->w_lines[0].wl_valid
            && curwin->w_topfill == curwin->w_old_topfill
            && curwin->w_botfill == curwin->w_old_botfill
            && curwin->w_topline == curwin->w_lines[0].wl_lnum)
           || (type == INVERTED
               && VIsual_active
               && curwin->w_old_cursor_lnum == curwin->w_cursor.lnum
               && curwin->w_old_visual_mode == VIsual_mode
               && (curwin->w_valid & VALID_VIRTCOL)
               && curwin->w_old_curswant == curwin->w_curswant)
           ))
    curwin->w_redr_type = type;

  /* Redraw the tab pages line if needed. */
  if (redraw_tabline || type >= NOT_VALID)
    draw_tabline();

  /*
   * Correct stored syntax highlighting info for changes in each displayed
   * buffer.  Each buffer must only be done once.
   */
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    if (wp->w_buffer->b_mod_set) {
      win_T       *wwp;

      /* Check if we already did this buffer. */
      for (wwp = firstwin; wwp != wp; wwp = wwp->w_next)
        if (wwp->w_buffer == wp->w_buffer)
          break;
      if (
        wwp == wp &&
        syntax_present(wp))
        syn_stack_apply_changes(wp->w_buffer);
    }
  }

  /*
   * Go from top to bottom through the windows, redrawing the ones that need
   * it.
   */
  did_one = FALSE;
  search_hl.rm.regprog = NULL;
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    if (wp->w_redr_type != 0) {
      if (!did_one) {
        did_one = TRUE;
        start_search_hl();
      }
      win_update(wp);
    }

    /* redraw status line after the window to minimize cursor movement */
    if (wp->w_redr_status) {
      win_redr_status(wp);
    }
  }
  end_search_hl();
  /* May need to redraw the popup menu. */
  if (pum_visible())
    pum_redraw();

  /* Reset b_mod_set flags.  Going through all windows is probably faster
   * than going through all buffers (there could be many buffers). */
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    wp->w_buffer->b_mod_set = false;
  }

  updating_screen = FALSE;

  /* Clear or redraw the command line.  Done last, because scrolling may
   * mess up the command line. */
  if (clear_cmdline || redraw_cmdline)
    showmode();

  /* May put up an introductory message when not editing a file */
  if (!did_intro)
    maybe_intro_message();
  did_intro = TRUE;

}

/*
 * Return TRUE if the cursor line in window "wp" may be concealed, according
 * to the 'concealcursor' option.
 */
int conceal_cursor_line(win_T *wp)
{
  int c;

  if (*wp->w_p_cocu == NUL)
    return FALSE;
  if (get_real_state() & VISUAL)
    c = 'v';
  else if (State & INSERT)
    c = 'i';
  else if (State & NORMAL)
    c = 'n';
  else if (State & CMDLINE)
    c = 'c';
  else
    return FALSE;
  return vim_strchr(wp->w_p_cocu, c) != NULL;
}

/*
 * Check if the cursor line needs to be redrawn because of 'concealcursor'.
 */
void conceal_check_cursur_line(void)
{
  if (curwin->w_p_cole > 0 && conceal_cursor_line(curwin)) {
    need_cursor_line_redraw = TRUE;
    /* Need to recompute cursor column, e.g., when starting Visual mode
     * without concealing. */
    curs_columns(TRUE);
  }
}

void update_single_line(win_T *wp, linenr_T lnum)
{
  int row;
  int j;

  if (lnum >= wp->w_topline && lnum < wp->w_botline
      && foldedCount(wp, lnum, &win_foldinfo) == 0) {
    row = 0;
    for (j = 0; j < wp->w_lines_valid; ++j) {
      if (lnum == wp->w_lines[j].wl_lnum) {
        init_search_hl(wp);
        start_search_hl();
        prepare_search_hl(wp, lnum);
        win_line(wp, lnum, row, row + wp->w_lines[j].wl_size, false);
        end_search_hl();
        break;
      }
      row += wp->w_lines[j].wl_size;
    }
  }
  need_cursor_line_redraw = FALSE;
}


/*
 * Prepare for updating one or more windows.
 * Caller must check for "updating_screen" already set to avoid recursiveness.
 */
static void update_prepare(void)
{
    updating_screen = TRUE;
    start_search_hl();
}

/*
 * Finish updating one or more windows.
 */
static void update_finish(void)
{
    if (redraw_cmdline) {
        showmode();
    }

    end_search_hl();
    updating_screen = FALSE;
}

void update_debug_sign(buf_T *buf, linenr_T lnum)
{
    int  doit = FALSE;
    win_foldinfo.fi_level = 0;

    /* update/delete a specific mark */
    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
      if (buf != NULL && lnum > 0) {
        if (wp->w_buffer == buf && lnum >= wp->w_topline
            && lnum < wp->w_botline) {
          if (wp->w_redraw_top == 0 || wp->w_redraw_top > lnum) {
            wp->w_redraw_top = lnum;
          }
          if (wp->w_redraw_bot == 0 || wp->w_redraw_bot < lnum) {
            wp->w_redraw_bot = lnum;
          }
          redraw_win_later(wp, VALID);
        }
      } else {
        redraw_win_later(wp, VALID);
      }
      if (wp->w_redr_type != 0) {
        doit = TRUE;
      }
    }

    /* Return when there is nothing to do, screen updating is already
     * happening (recursive call) or still starting up. */
    if (!doit || updating_screen || starting) {
        return;
    }

    /* update all windows that need updating */
    update_prepare();

    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
      if (wp->w_redr_type != 0) {
        win_update(wp);
      }
      if (wp->w_redr_status) {
        win_redr_status(wp);
      }
    }

    update_finish();
}

/*
 * Return TRUE when window "wp" has a column to draw signs in.
 */
static int draw_signcolumn(win_T *wp)
{
    return (wp->w_buffer->b_signlist != NULL);
}


/*
 * Update a single window.
 *
 * This may cause the windows below it also to be redrawn (when clearing the
 * screen or scrolling lines).
 *
 * How the window is redrawn depends on wp->w_redr_type.  Each type also
 * implies the one below it.
 * NOT_VALID	redraw the whole window
 * SOME_VALID	redraw the whole window but do scroll when possible
 * REDRAW_TOP	redraw the top w_upd_rows window lines, otherwise like VALID
 * INVERTED	redraw the changed part of the Visual area
 * INVERTED_ALL	redraw the whole Visual area
 * VALID	1. scroll up/down to adjust for a changed w_topline
 *		2. update lines at the top when scrolled down
 *		3. redraw changed text:
 *		   - if wp->w_buffer->b_mod_set set, update lines between
 *		     b_mod_top and b_mod_bot.
 *		   - if wp->w_redraw_top non-zero, redraw lines between
 *		     wp->w_redraw_top and wp->w_redr_bot.
 *		   - continue redrawing when syntax status is invalid.
 *		4. if scrolled up, update lines at the bottom.
 * This results in three areas that may need updating:
 * top:	from first row to top_end (when scrolled down)
 * mid: from mid_start to mid_end (update inversion or changed text)
 * bot: from bot_start to last row (when scrolled up)
 */
static void win_update(win_T *wp)
{
  buf_T       *buf = wp->w_buffer;
  int type;
  int top_end = 0;              /* Below last row of the top area that needs
                                   updating.  0 when no top area updating. */
  int mid_start = 999;          /* first row of the mid area that needs
                                   updating.  999 when no mid area updating. */
  int mid_end = 0;              /* Below last row of the mid area that needs
                                   updating.  0 when no mid area updating. */
  int bot_start = 999;          /* first row of the bot area that needs
                                   updating.  999 when no bot area updating */
  int scrolled_down = FALSE;            /* TRUE when scrolled down when
                                           w_topline got smaller a bit */
  matchitem_T *cur;             /* points to the match list */
  int top_to_mod = FALSE;              /* redraw above mod_top */

  int row;                      /* current window row to display */
  linenr_T lnum;                /* current buffer lnum to display */
  int idx;                      /* current index in w_lines[] */
  int srow;                     /* starting row of the current line */

  int eof = FALSE;              /* if TRUE, we hit the end of the file */
  int didline = FALSE;           /* if TRUE, we finished the last line */
  int i;
  long j;
  static int recursive = FALSE;         /* being called recursively */
  int old_botline = wp->w_botline;
  long fold_count;
  /* remember what happened to the previous line, to know if
   * check_visual_highlight() can be used */
#define DID_NONE 1      /* didn't update a line */
#define DID_LINE 2      /* updated a normal line */
#define DID_FOLD 3      /* updated a folded line */
  int did_update = DID_NONE;
  linenr_T syntax_last_parsed = 0;              /* last parsed text line */
  linenr_T mod_top = 0;
  linenr_T mod_bot = 0;
  int save_got_int;

  type = wp->w_redr_type;

  if (type == NOT_VALID) {
    wp->w_redr_status = TRUE;
    wp->w_lines_valid = 0;
  }

  /* Window is zero-height: nothing to draw. */
  if (wp->w_height == 0) {
    wp->w_redr_type = 0;
    return;
  }

  /* Window is zero-width: Only need to draw the separator. */
  if (wp->w_width == 0) {
    /* draw the vertical separator right of this window */
    draw_vsep_win(wp, 0);
    wp->w_redr_type = 0;
    return;
  }

  init_search_hl(wp);

  /* Force redraw when width of 'number' or 'relativenumber' column
   * changes. */
  i = (wp->w_p_nu || wp->w_p_rnu) ? number_width(wp) : 0;
  if (wp->w_nrwidth != i) {
    type = NOT_VALID;
    wp->w_nrwidth = i;
  } else if (buf->b_mod_set && buf->b_mod_xlines != 0 && wp->w_redraw_top != 0) {
    /*
     * When there are both inserted/deleted lines and specific lines to be
     * redrawn, w_redraw_top and w_redraw_bot may be invalid, just redraw
     * everything (only happens when redrawing is off for while).
     */
    type = NOT_VALID;
  } else {
    /*
     * Set mod_top to the first line that needs displaying because of
     * changes.  Set mod_bot to the first line after the changes.
     */
    mod_top = wp->w_redraw_top;
    if (wp->w_redraw_bot != 0)
      mod_bot = wp->w_redraw_bot + 1;
    else
      mod_bot = 0;
    wp->w_redraw_top = 0;       /* reset for next time */
    wp->w_redraw_bot = 0;
    if (buf->b_mod_set) {
      if (mod_top == 0 || mod_top > buf->b_mod_top) {
        mod_top = buf->b_mod_top;
        /* Need to redraw lines above the change that may be included
         * in a pattern match. */
        if (syntax_present(wp)) {
          mod_top -= buf->b_s.b_syn_sync_linebreaks;
          if (mod_top < 1)
            mod_top = 1;
        }
      }
      if (mod_bot == 0 || mod_bot < buf->b_mod_bot)
        mod_bot = buf->b_mod_bot;

      /* When 'hlsearch' is on and using a multi-line search pattern, a
       * change in one line may make the Search highlighting in a
       * previous line invalid.  Simple solution: redraw all visible
       * lines above the change.
       * Same for a match pattern.
       */
      if (search_hl.rm.regprog != NULL
          && re_multiline(search_hl.rm.regprog))
        top_to_mod = TRUE;
      else {
        cur = wp->w_match_head;
        while (cur != NULL) {
          if (cur->match.regprog != NULL
              && re_multiline(cur->match.regprog)) {
            top_to_mod = TRUE;
            break;
          }
          cur = cur->next;
        }
      }
    }
    if (mod_top != 0 && hasAnyFolding(wp)) {
      linenr_T lnumt, lnumb;

      /*
       * A change in a line can cause lines above it to become folded or
       * unfolded.  Find the top most buffer line that may be affected.
       * If the line was previously folded and displayed, get the first
       * line of that fold.  If the line is folded now, get the first
       * folded line.  Use the minimum of these two.
       */

      /* Find last valid w_lines[] entry above mod_top.  Set lnumt to
       * the line below it.  If there is no valid entry, use w_topline.
       * Find the first valid w_lines[] entry below mod_bot.  Set lnumb
       * to this line.  If there is no valid entry, use MAXLNUM. */
      lnumt = wp->w_topline;
      lnumb = MAXLNUM;
      for (i = 0; i < wp->w_lines_valid; ++i)
        if (wp->w_lines[i].wl_valid) {
          if (wp->w_lines[i].wl_lastlnum < mod_top)
            lnumt = wp->w_lines[i].wl_lastlnum + 1;
          if (lnumb == MAXLNUM && wp->w_lines[i].wl_lnum >= mod_bot) {
            lnumb = wp->w_lines[i].wl_lnum;
            /* When there is a fold column it might need updating
             * in the next line ("J" just above an open fold). */
            if (wp->w_p_fdc > 0)
              ++lnumb;
          }
        }

      (void)hasFoldingWin(wp, mod_top, &mod_top, NULL, TRUE, NULL);
      if (mod_top > lnumt)
        mod_top = lnumt;

      /* Now do the same for the bottom line (one above mod_bot). */
      --mod_bot;
      (void)hasFoldingWin(wp, mod_bot, NULL, &mod_bot, TRUE, NULL);
      ++mod_bot;
      if (mod_bot < lnumb)
        mod_bot = lnumb;
    }

    /* When a change starts above w_topline and the end is below
     * w_topline, start redrawing at w_topline.
     * If the end of the change is above w_topline: do like no change was
     * made, but redraw the first line to find changes in syntax. */
    if (mod_top != 0 && mod_top < wp->w_topline) {
      if (mod_bot > wp->w_topline)
        mod_top = wp->w_topline;
      else if (syntax_present(wp))
        top_end = 1;
    }

    /* When line numbers are displayed need to redraw all lines below
     * inserted/deleted lines. */
    if (mod_top != 0 && buf->b_mod_xlines != 0 && wp->w_p_nu)
      mod_bot = MAXLNUM;
  }

  /*
   * When only displaying the lines at the top, set top_end.  Used when
   * window has scrolled down for msg_scrolled.
   */
  if (type == REDRAW_TOP) {
    j = 0;
    for (i = 0; i < wp->w_lines_valid; ++i) {
      j += wp->w_lines[i].wl_size;
      if (j >= wp->w_upd_rows) {
        top_end = j;
        break;
      }
    }
    if (top_end == 0)
      /* not found (cannot happen?): redraw everything */
      type = NOT_VALID;
    else
      /* top area defined, the rest is VALID */
      type = VALID;
  }

  /* Trick: we want to avoid clearing the screen twice.  screenclear() will
   * set "screen_cleared" to TRUE.  The special value MAYBE (which is still
   * non-zero and thus not FALSE) will indicate that screenclear() was not
   * called. */
  if (screen_cleared)
    screen_cleared = MAYBE;

  /*
   * If there are no changes on the screen that require a complete redraw,
   * handle three cases:
   * 1: we are off the top of the screen by a few lines: scroll down
   * 2: wp->w_topline is below wp->w_lines[0].wl_lnum: may scroll up
   * 3: wp->w_topline is wp->w_lines[0].wl_lnum: find first entry in
   *    w_lines[] that needs updating.
   */
  if ((type == VALID || type == SOME_VALID
       || type == INVERTED || type == INVERTED_ALL)
      && !wp->w_botfill && !wp->w_old_botfill
      ) {
    if (mod_top != 0 && wp->w_topline == mod_top) {
      /*
       * w_topline is the first changed line, the scrolling will be done
       * further down.
       */
    } else if (wp->w_lines[0].wl_valid
               && (wp->w_topline < wp->w_lines[0].wl_lnum
                   || (wp->w_topline == wp->w_lines[0].wl_lnum
                       && wp->w_topfill > wp->w_old_topfill)
                   )) {
      /*
       * New topline is above old topline: May scroll down.
       */
      if (hasAnyFolding(wp)) {
        linenr_T ln;

        /* count the number of lines we are off, counting a sequence
         * of folded lines as one */
        j = 0;
        for (ln = wp->w_topline; ln < wp->w_lines[0].wl_lnum; ++ln) {
          ++j;
          if (j >= wp->w_height - 2)
            break;
          (void)hasFoldingWin(wp, ln, NULL, &ln, TRUE, NULL);
        }
      } else
        j = wp->w_lines[0].wl_lnum - wp->w_topline;
      if (j < wp->w_height - 2) {               /* not too far off */
        i = plines_m_win(wp, wp->w_topline, wp->w_lines[0].wl_lnum - 1);
        /* insert extra lines for previously invisible filler lines */
        if (wp->w_lines[0].wl_lnum != wp->w_topline)
          i += diff_check_fill(wp, wp->w_lines[0].wl_lnum)
               - wp->w_old_topfill;
        if (i < wp->w_height - 2) {             /* less than a screen off */
          /*
           * Try to insert the correct number of lines.
           * If not the last window, delete the lines at the bottom.
           * win_ins_lines may fail when the terminal can't do it.
           */
          if (i > 0)
            check_for_delay(FALSE);
          if (win_ins_lines(wp, 0, i, FALSE, wp == firstwin) == OK) {
            if (wp->w_lines_valid != 0) {
              /* Need to update rows that are new, stop at the
               * first one that scrolled down. */
              top_end = i;
              scrolled_down = TRUE;

              /* Move the entries that were scrolled, disable
               * the entries for the lines to be redrawn. */
              if ((wp->w_lines_valid += j) > wp->w_height)
                wp->w_lines_valid = wp->w_height;
              for (idx = wp->w_lines_valid; idx - j >= 0; idx--)
                wp->w_lines[idx] = wp->w_lines[idx - j];
              while (idx >= 0)
                wp->w_lines[idx--].wl_valid = FALSE;
            }
          } else
            mid_start = 0;                      /* redraw all lines */
        } else
          mid_start = 0;                        /* redraw all lines */
      } else
        mid_start = 0;                  /* redraw all lines */
    } else {
      /*
       * New topline is at or below old topline: May scroll up.
       * When topline didn't change, find first entry in w_lines[] that
       * needs updating.
       */

      /* try to find wp->w_topline in wp->w_lines[].wl_lnum */
      j = -1;
      row = 0;
      for (i = 0; i < wp->w_lines_valid; i++) {
        if (wp->w_lines[i].wl_valid
            && wp->w_lines[i].wl_lnum == wp->w_topline) {
          j = i;
          break;
        }
        row += wp->w_lines[i].wl_size;
      }
      if (j == -1) {
        /* if wp->w_topline is not in wp->w_lines[].wl_lnum redraw all
         * lines */
        mid_start = 0;
      } else {
        /*
         * Try to delete the correct number of lines.
         * wp->w_topline is at wp->w_lines[i].wl_lnum.
         */
        /* If the topline didn't change, delete old filler lines,
         * otherwise delete filler lines of the new topline... */
        if (wp->w_lines[0].wl_lnum == wp->w_topline)
          row += wp->w_old_topfill;
        else
          row += diff_check_fill(wp, wp->w_topline);
        /* ... but don't delete new filler lines. */
        row -= wp->w_topfill;
        if (row > 0) {
          check_for_delay(FALSE);
          if (win_del_lines(wp, 0, row, FALSE, wp == firstwin) == OK)
            bot_start = wp->w_height - row;
          else
            mid_start = 0;                      /* redraw all lines */
        }
        if ((row == 0 || bot_start < 999) && wp->w_lines_valid != 0) {
          /*
           * Skip the lines (below the deleted lines) that are still
           * valid and don't need redrawing.	Copy their info
           * upwards, to compensate for the deleted lines.  Set
           * bot_start to the first row that needs redrawing.
           */
          bot_start = 0;
          idx = 0;
          for (;; ) {
            wp->w_lines[idx] = wp->w_lines[j];
            /* stop at line that didn't fit, unless it is still
             * valid (no lines deleted) */
            if (row > 0 && bot_start + row
                + (int)wp->w_lines[j].wl_size > wp->w_height) {
              wp->w_lines_valid = idx + 1;
              break;
            }
            bot_start += wp->w_lines[idx++].wl_size;

            /* stop at the last valid entry in w_lines[].wl_size */
            if (++j >= wp->w_lines_valid) {
              wp->w_lines_valid = idx;
              break;
            }
          }
          /* Correct the first entry for filler lines at the top
           * when it won't get updated below. */
          if (wp->w_p_diff && bot_start > 0)
            wp->w_lines[0].wl_size =
              plines_win_nofill(wp, wp->w_topline, TRUE)
              + wp->w_topfill;
        }
      }
    }

    /* When starting redraw in the first line, redraw all lines.  When
     * there is only one window it's probably faster to clear the screen
     * first. */
    if (mid_start == 0) {
      mid_end = wp->w_height;
      if (lastwin == firstwin) {
        /* Clear the screen when it was not done by win_del_lines() or
         * win_ins_lines() above, "screen_cleared" is FALSE or MAYBE
         * then. */
        if (screen_cleared != TRUE)
          screenclear();
        /* The screen was cleared, redraw the tab pages line. */
        if (redraw_tabline)
          draw_tabline();
      }
    }

    /* When win_del_lines() or win_ins_lines() caused the screen to be
     * cleared (only happens for the first window) or when screenclear()
     * was called directly above, "must_redraw" will have been set to
     * NOT_VALID, need to reset it here to avoid redrawing twice. */
    if (screen_cleared == TRUE)
      must_redraw = 0;
  } else {
    /* Not VALID or INVERTED: redraw all lines. */
    mid_start = 0;
    mid_end = wp->w_height;
  }

  if (type == SOME_VALID) {
    /* SOME_VALID: redraw all lines. */
    mid_start = 0;
    mid_end = wp->w_height;
    type = NOT_VALID;
  }

  /* check if we are updating or removing the inverted part */
  if ((VIsual_active && buf == curwin->w_buffer)
      || (wp->w_old_cursor_lnum != 0 && type != NOT_VALID)) {
    linenr_T from, to;

    if (VIsual_active) {
      if (VIsual_active
          && (VIsual_mode != wp->w_old_visual_mode
              || type == INVERTED_ALL)) {
        /*
         * If the type of Visual selection changed, redraw the whole
         * selection.  Also when the ownership of the X selection is
         * gained or lost.
         */
        if (curwin->w_cursor.lnum < VIsual.lnum) {
          from = curwin->w_cursor.lnum;
          to = VIsual.lnum;
        } else {
          from = VIsual.lnum;
          to = curwin->w_cursor.lnum;
        }
        /* redraw more when the cursor moved as well */
        if (wp->w_old_cursor_lnum < from)
          from = wp->w_old_cursor_lnum;
        if (wp->w_old_cursor_lnum > to)
          to = wp->w_old_cursor_lnum;
        if (wp->w_old_visual_lnum < from)
          from = wp->w_old_visual_lnum;
        if (wp->w_old_visual_lnum > to)
          to = wp->w_old_visual_lnum;
      } else {
        /*
         * Find the line numbers that need to be updated: The lines
         * between the old cursor position and the current cursor
         * position.  Also check if the Visual position changed.
         */
        if (curwin->w_cursor.lnum < wp->w_old_cursor_lnum) {
          from = curwin->w_cursor.lnum;
          to = wp->w_old_cursor_lnum;
        } else {
          from = wp->w_old_cursor_lnum;
          to = curwin->w_cursor.lnum;
          if (from == 0)                /* Visual mode just started */
            from = to;
        }

        if (VIsual.lnum != wp->w_old_visual_lnum
            || VIsual.col != wp->w_old_visual_col) {
          if (wp->w_old_visual_lnum < from
              && wp->w_old_visual_lnum != 0)
            from = wp->w_old_visual_lnum;
          if (wp->w_old_visual_lnum > to)
            to = wp->w_old_visual_lnum;
          if (VIsual.lnum < from)
            from = VIsual.lnum;
          if (VIsual.lnum > to)
            to = VIsual.lnum;
        }
      }

      /*
       * If in block mode and changed column or curwin->w_curswant:
       * update all lines.
       * First compute the actual start and end column.
       */
      if (VIsual_mode == Ctrl_V) {
        colnr_T fromc, toc;
        int save_ve_flags = ve_flags;

        if (curwin->w_p_lbr)
          ve_flags = VE_ALL;

        getvcols(wp, &VIsual, &curwin->w_cursor, &fromc, &toc);
        ve_flags = save_ve_flags;
        ++toc;
        if (curwin->w_curswant == MAXCOL)
          toc = MAXCOL;

        if (fromc != wp->w_old_cursor_fcol
            || toc != wp->w_old_cursor_lcol) {
          if (from > VIsual.lnum)
            from = VIsual.lnum;
          if (to < VIsual.lnum)
            to = VIsual.lnum;
        }
        wp->w_old_cursor_fcol = fromc;
        wp->w_old_cursor_lcol = toc;
      }
    } else {
      /* Use the line numbers of the old Visual area. */
      if (wp->w_old_cursor_lnum < wp->w_old_visual_lnum) {
        from = wp->w_old_cursor_lnum;
        to = wp->w_old_visual_lnum;
      } else {
        from = wp->w_old_visual_lnum;
        to = wp->w_old_cursor_lnum;
      }
    }

    /*
     * There is no need to update lines above the top of the window.
     */
    if (from < wp->w_topline)
      from = wp->w_topline;

    /*
     * If we know the value of w_botline, use it to restrict the update to
     * the lines that are visible in the window.
     */
    if (wp->w_valid & VALID_BOTLINE) {
      if (from >= wp->w_botline)
        from = wp->w_botline - 1;
      if (to >= wp->w_botline)
        to = wp->w_botline - 1;
    }

    /*
     * Find the minimal part to be updated.
     * Watch out for scrolling that made entries in w_lines[] invalid.
     * E.g., CTRL-U makes the first half of w_lines[] invalid and sets
     * top_end; need to redraw from top_end to the "to" line.
     * A middle mouse click with a Visual selection may change the text
     * above the Visual area and reset wl_valid, do count these for
     * mid_end (in srow).
     */
    if (mid_start > 0) {
      lnum = wp->w_topline;
      idx = 0;
      srow = 0;
      if (scrolled_down)
        mid_start = top_end;
      else
        mid_start = 0;
      while (lnum < from && idx < wp->w_lines_valid) {          /* find start */
        if (wp->w_lines[idx].wl_valid)
          mid_start += wp->w_lines[idx].wl_size;
        else if (!scrolled_down)
          srow += wp->w_lines[idx].wl_size;
        ++idx;
        if (idx < wp->w_lines_valid && wp->w_lines[idx].wl_valid)
          lnum = wp->w_lines[idx].wl_lnum;
        else
          ++lnum;
      }
      srow += mid_start;
      mid_end = wp->w_height;
      for (; idx < wp->w_lines_valid; ++idx) {                  /* find end */
        if (wp->w_lines[idx].wl_valid
            && wp->w_lines[idx].wl_lnum >= to + 1) {
          /* Only update until first row of this line */
          mid_end = srow;
          break;
        }
        srow += wp->w_lines[idx].wl_size;
      }
    }
  }

  if (VIsual_active && buf == curwin->w_buffer) {
    wp->w_old_visual_mode = VIsual_mode;
    wp->w_old_cursor_lnum = curwin->w_cursor.lnum;
    wp->w_old_visual_lnum = VIsual.lnum;
    wp->w_old_visual_col = VIsual.col;
    wp->w_old_curswant = curwin->w_curswant;
  } else {
    wp->w_old_visual_mode = 0;
    wp->w_old_cursor_lnum = 0;
    wp->w_old_visual_lnum = 0;
    wp->w_old_visual_col = 0;
  }

  /* reset got_int, otherwise regexp won't work */
  save_got_int = got_int;
  got_int = 0;
  win_foldinfo.fi_level = 0;

  /*
   * Update all the window rows.
   */
  idx = 0;              /* first entry in w_lines[].wl_size */
  row = 0;
  srow = 0;
  lnum = wp->w_topline;         /* first line shown in window */
  for (;; ) {
    /* stop updating when reached the end of the window (check for _past_
     * the end of the window is at the end of the loop) */
    if (row == wp->w_height) {
      didline = TRUE;
      break;
    }

    /* stop updating when hit the end of the file */
    if (lnum > buf->b_ml.ml_line_count) {
      eof = TRUE;
      break;
    }

    /* Remember the starting row of the line that is going to be dealt
     * with.  It is used further down when the line doesn't fit. */
    srow = row;

    /*
     * Update a line when it is in an area that needs updating, when it
     * has changes or w_lines[idx] is invalid.
     * bot_start may be halfway through a wrapped line after using
     * win_del_lines(), check if the current line includes it.
     * When syntax folding is being used, the saved syntax states will
     * already have been updated, we can't see where the syntax state is
     * the same again, just update until the end of the window.
     */
    if (row < top_end
        || (row >= mid_start && row < mid_end)
        || top_to_mod
        || idx >= wp->w_lines_valid
        || (row + wp->w_lines[idx].wl_size > bot_start)
        || (mod_top != 0
            && (lnum == mod_top
                || (lnum >= mod_top
                    && (lnum < mod_bot
                        || did_update == DID_FOLD
                        || (did_update == DID_LINE
                            && syntax_present(wp)
                            && (
                              (foldmethodIsSyntax(wp)
                               && hasAnyFolding(wp)) ||
                              syntax_check_changed(lnum)))
                        // match in fixed position might need redraw
                        // if lines were inserted or deleted
                        || (wp->w_match_head != NULL && buf->b_mod_xlines != 0)
                        ))))) {
      if (lnum == mod_top)
        top_to_mod = FALSE;

      /*
       * When at start of changed lines: May scroll following lines
       * up or down to minimize redrawing.
       * Don't do this when the change continues until the end.
       * Don't scroll when dollar_vcol >= 0, keep the "$".
       */
      if (lnum == mod_top
          && mod_bot != MAXLNUM
          && !(dollar_vcol >= 0 && mod_bot == mod_top + 1)) {
        int old_rows = 0;
        int new_rows = 0;
        int xtra_rows;
        linenr_T l;

        /* Count the old number of window rows, using w_lines[], which
         * should still contain the sizes for the lines as they are
         * currently displayed. */
        for (i = idx; i < wp->w_lines_valid; ++i) {
          /* Only valid lines have a meaningful wl_lnum.  Invalid
           * lines are part of the changed area. */
          if (wp->w_lines[i].wl_valid
              && wp->w_lines[i].wl_lnum == mod_bot)
            break;
          old_rows += wp->w_lines[i].wl_size;
          if (wp->w_lines[i].wl_valid
              && wp->w_lines[i].wl_lastlnum + 1 == mod_bot) {
            /* Must have found the last valid entry above mod_bot.
             * Add following invalid entries. */
            ++i;
            while (i < wp->w_lines_valid
                   && !wp->w_lines[i].wl_valid)
              old_rows += wp->w_lines[i++].wl_size;
            break;
          }
        }

        if (i >= wp->w_lines_valid) {
          /* We can't find a valid line below the changed lines,
           * need to redraw until the end of the window.
           * Inserting/deleting lines has no use. */
          bot_start = 0;
        } else {
          /* Able to count old number of rows: Count new window
           * rows, and may insert/delete lines */
          j = idx;
          for (l = lnum; l < mod_bot; ++l) {
            if (hasFoldingWin(wp, l, NULL, &l, TRUE, NULL))
              ++new_rows;
            else if (l == wp->w_topline)
              new_rows += plines_win_nofill(wp, l, TRUE)
                          + wp->w_topfill;
            else
              new_rows += plines_win(wp, l, TRUE);
            ++j;
            if (new_rows > wp->w_height - row - 2) {
              /* it's getting too much, must redraw the rest */
              new_rows = 9999;
              break;
            }
          }
          xtra_rows = new_rows - old_rows;
          if (xtra_rows < 0) {
            /* May scroll text up.  If there is not enough
             * remaining text or scrolling fails, must redraw the
             * rest.  If scrolling works, must redraw the text
             * below the scrolled text. */
            if (row - xtra_rows >= wp->w_height - 2)
              mod_bot = MAXLNUM;
            else {
              check_for_delay(FALSE);
              if (win_del_lines(wp, row,
                      -xtra_rows, FALSE, FALSE) == FAIL)
                mod_bot = MAXLNUM;
              else
                bot_start = wp->w_height + xtra_rows;
            }
          } else if (xtra_rows > 0) {
            /* May scroll text down.  If there is not enough
             * remaining text of scrolling fails, must redraw the
             * rest. */
            if (row + xtra_rows >= wp->w_height - 2)
              mod_bot = MAXLNUM;
            else {
              check_for_delay(FALSE);
              if (win_ins_lines(wp, row + old_rows,
                      xtra_rows, FALSE, FALSE) == FAIL)
                mod_bot = MAXLNUM;
              else if (top_end > row + old_rows)
                /* Scrolled the part at the top that requires
                 * updating down. */
                top_end += xtra_rows;
            }
          }

          /* When not updating the rest, may need to move w_lines[]
           * entries. */
          if (mod_bot != MAXLNUM && i != j) {
            if (j < i) {
              int x = row + new_rows;

              /* move entries in w_lines[] upwards */
              for (;; ) {
                /* stop at last valid entry in w_lines[] */
                if (i >= wp->w_lines_valid) {
                  wp->w_lines_valid = j;
                  break;
                }
                wp->w_lines[j] = wp->w_lines[i];
                /* stop at a line that won't fit */
                if (x + (int)wp->w_lines[j].wl_size
                    > wp->w_height) {
                  wp->w_lines_valid = j + 1;
                  break;
                }
                x += wp->w_lines[j++].wl_size;
                ++i;
              }
              if (bot_start > x)
                bot_start = x;
            } else {       /* j > i */
                             /* move entries in w_lines[] downwards */
              j -= i;
              wp->w_lines_valid += j;
              if (wp->w_lines_valid > wp->w_height)
                wp->w_lines_valid = wp->w_height;
              for (i = wp->w_lines_valid; i - j >= idx; --i)
                wp->w_lines[i] = wp->w_lines[i - j];

              /* The w_lines[] entries for inserted lines are
               * now invalid, but wl_size may be used above.
               * Reset to zero. */
              while (i >= idx) {
                wp->w_lines[i].wl_size = 0;
                wp->w_lines[i--].wl_valid = FALSE;
              }
            }
          }
        }
      }

      /*
       * When lines are folded, display one line for all of them.
       * Otherwise, display normally (can be several display lines when
       * 'wrap' is on).
       */
      fold_count = foldedCount(wp, lnum, &win_foldinfo);
      if (fold_count != 0) {
        fold_line(wp, fold_count, &win_foldinfo, lnum, row);
        ++row;
        --fold_count;
        wp->w_lines[idx].wl_folded = TRUE;
        wp->w_lines[idx].wl_lastlnum = lnum + fold_count;
        did_update = DID_FOLD;
      } else if (idx < wp->w_lines_valid
                 && wp->w_lines[idx].wl_valid
                 && wp->w_lines[idx].wl_lnum == lnum
                 && lnum > wp->w_topline
                 && !(dy_flags & DY_LASTLINE)
                 && srow + wp->w_lines[idx].wl_size > wp->w_height
                 && diff_check_fill(wp, lnum) == 0
                 ) {
        /* This line is not going to fit.  Don't draw anything here,
         * will draw "@  " lines below. */
        row = wp->w_height + 1;
      } else {
        prepare_search_hl(wp, lnum);
        /* Let the syntax stuff know we skipped a few lines. */
        if (syntax_last_parsed != 0 && syntax_last_parsed + 1 < lnum
            && syntax_present(wp))
          syntax_end_parsing(syntax_last_parsed + 1);

        /*
         * Display one line.
         */
        row = win_line(wp, lnum, srow, wp->w_height, mod_top == 0);

        wp->w_lines[idx].wl_folded = FALSE;
        wp->w_lines[idx].wl_lastlnum = lnum;
        did_update = DID_LINE;
        syntax_last_parsed = lnum;
      }

      wp->w_lines[idx].wl_lnum = lnum;
      wp->w_lines[idx].wl_valid = TRUE;
      if (row > wp->w_height) {         /* past end of screen */
        /* we may need the size of that too long line later on */
        if (dollar_vcol == -1)
          wp->w_lines[idx].wl_size = plines_win(wp, lnum, TRUE);
        ++idx;
        break;
      }
      if (dollar_vcol == -1)
        wp->w_lines[idx].wl_size = row - srow;
      ++idx;
      lnum += fold_count + 1;
    } else {
      /* This line does not need updating, advance to the next one */
      row += wp->w_lines[idx++].wl_size;
      if (row > wp->w_height)           /* past end of screen */
        break;
      lnum = wp->w_lines[idx - 1].wl_lastlnum + 1;
      did_update = DID_NONE;
    }

    if (lnum > buf->b_ml.ml_line_count) {
      eof = TRUE;
      break;
    }
  }
  /*
   * End of loop over all window lines.
   */


  if (idx > wp->w_lines_valid)
    wp->w_lines_valid = idx;

  /*
   * Let the syntax stuff know we stop parsing here.
   */
  if (syntax_last_parsed != 0 && syntax_present(wp))
    syntax_end_parsing(syntax_last_parsed + 1);

  /*
   * If we didn't hit the end of the file, and we didn't finish the last
   * line we were working on, then the line didn't fit.
   */
  wp->w_empty_rows = 0;
  wp->w_filler_rows = 0;
  if (!eof && !didline) {
    if (lnum == wp->w_topline) {
      /*
       * Single line that does not fit!
       * Don't overwrite it, it can be edited.
       */
      wp->w_botline = lnum + 1;
    } else if (diff_check_fill(wp, lnum) >= wp->w_height - srow) {
      /* Window ends in filler lines. */
      wp->w_botline = lnum;
      wp->w_filler_rows = wp->w_height - srow;
    } else if (dy_flags & DY_LASTLINE) {      /* 'display' has "lastline" */
      /*
       * Last line isn't finished: Display "@@@" at the end.
       */
      screen_fill(wp->w_winrow + wp->w_height - 1,
                  wp->w_winrow + wp->w_height,
                  W_ENDCOL(wp) - 3, W_ENDCOL(wp),
                  '@', '@', hl_attr(HLF_AT));
      set_empty_rows(wp, srow);
      wp->w_botline = lnum;
    } else {
      win_draw_end(wp, '@', ' ', srow, wp->w_height, HLF_AT);
      wp->w_botline = lnum;
    }
  } else {
    draw_vsep_win(wp, row);
    if (eof) {                  /* we hit the end of the file */
      wp->w_botline = buf->b_ml.ml_line_count + 1;
      j = diff_check_fill(wp, wp->w_botline);
      if (j > 0 && !wp->w_botfill) {
        /*
         * Display filler lines at the end of the file
         */
        if (char2cells(fill_diff) > 1)
          i = '-';
        else
          i = fill_diff;
        if (row + j > wp->w_height)
          j = wp->w_height - row;
        win_draw_end(wp, i, i, row, row + (int)j, HLF_DED);
        row += j;
      }
    } else if (dollar_vcol == -1)
      wp->w_botline = lnum;

    /* make sure the rest of the screen is blank */
    /* put '~'s on rows that aren't part of the file. */
    win_draw_end(wp, '~', ' ', row, wp->w_height, HLF_EOB);
  }

  /* Reset the type of redrawing required, the window has been updated. */
  wp->w_redr_type = 0;
  wp->w_old_topfill = wp->w_topfill;
  wp->w_old_botfill = wp->w_botfill;

  if (dollar_vcol == -1) {
    /*
     * There is a trick with w_botline.  If we invalidate it on each
     * change that might modify it, this will cause a lot of expensive
     * calls to plines() in update_topline() each time.  Therefore the
     * value of w_botline is often approximated, and this value is used to
     * compute the value of w_topline.  If the value of w_botline was
     * wrong, check that the value of w_topline is correct (cursor is on
     * the visible part of the text).  If it's not, we need to redraw
     * again.  Mostly this just means scrolling up a few lines, so it
     * doesn't look too bad.  Only do this for the current window (where
     * changes are relevant).
     */
    wp->w_valid |= VALID_BOTLINE;
    if (wp == curwin && wp->w_botline != old_botline && !recursive) {
      recursive = TRUE;
      curwin->w_valid &= ~VALID_TOPLINE;
      update_topline();         /* may invalidate w_botline again */
      if (must_redraw != 0) {
        /* Don't update for changes in buffer again. */
        i = curbuf->b_mod_set;
        curbuf->b_mod_set = false;
        win_update(curwin);
        must_redraw = 0;
        curbuf->b_mod_set = i;
      }
      recursive = FALSE;
    }
  }

  /* restore got_int, unless CTRL-C was hit while redrawing */
  if (!got_int)
    got_int = save_got_int;
}


/*
 * Clear the rest of the window and mark the unused lines with "c1".  use "c2"
 * as the filler character.
 */
static void win_draw_end(win_T *wp, int c1, int c2, int row, int endrow, hlf_T hl)
{
  int n = 0;
# define FDC_OFF n

  if (wp->w_p_rl) {
    /* No check for cmdline window: should never be right-left. */
    n = wp->w_p_fdc;

    if (n > 0) {
      /* draw the fold column at the right */
      if (n > wp->w_width)
        n = wp->w_width;
      screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                  W_ENDCOL(wp) - n, W_ENDCOL(wp),
                  ' ', ' ', hl_attr(HLF_FC));
    }

    if (draw_signcolumn(wp)) {
        int nn = n + 2;

        /* draw the sign column left of the fold column */
        if (nn > wp->w_width) {
            nn = wp->w_width;
        }
        screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                    W_ENDCOL(wp) - nn, W_ENDCOL(wp) - n,
                    ' ', ' ', hl_attr(HLF_SC));
        n = nn;
    }

    screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                wp->w_wincol, W_ENDCOL(wp) - 1 - FDC_OFF,
                c2, c2, hl_attr(hl));
    screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                W_ENDCOL(wp) - 1 - FDC_OFF, W_ENDCOL(wp) - FDC_OFF,
                c1, c2, hl_attr(hl));
  } else {
    if (cmdwin_type != 0 && wp == curwin) {
      /* draw the cmdline character in the leftmost column */
      n = 1;
      if (n > wp->w_width)
        n = wp->w_width;
      screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                  wp->w_wincol, wp->w_wincol + n,
                  cmdwin_type, ' ', hl_attr(HLF_AT));
    }
    if (wp->w_p_fdc > 0) {
      int nn = n + wp->w_p_fdc;

      /* draw the fold column at the left */
      if (nn > wp->w_width)
        nn = wp->w_width;
      screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                  wp->w_wincol + n, wp->w_wincol + nn,
                  ' ', ' ', hl_attr(HLF_FC));
      n = nn;
    }

    if (draw_signcolumn(wp))
    {
        int nn = n + 2;

        /* draw the sign column after the fold column */
        if (nn > wp->w_width) {
            nn = wp->w_width;
        }
        screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                    wp->w_wincol + n, wp->w_wincol + nn,
                    ' ', ' ', hl_attr(HLF_SC));
        n = nn;
    }

    screen_fill(wp->w_winrow + row, wp->w_winrow + endrow,
                wp->w_wincol + FDC_OFF, W_ENDCOL(wp),
                c1, c2, hl_attr(hl));
  }
  set_empty_rows(wp, row);
}


/*
 * Advance **color_cols and return TRUE when there are columns to draw.
 */
static int advance_color_col(int vcol, int **color_cols)
{
  while (**color_cols >= 0 && vcol > **color_cols)
    ++*color_cols;
  return **color_cols >= 0;
}

/*
 * Display one folded line.
 */
static void fold_line(win_T *wp, long fold_count, foldinfo_T *foldinfo, linenr_T lnum, int row)
{
  char_u buf[51];
  pos_T       *top, *bot;
  linenr_T lnume = lnum + fold_count - 1;
  int len;
  char_u      *text;
  int fdc;
  int col;
  int txtcol;
  int off = (int)(current_ScreenLine - ScreenLines);
  int ri;

  /* Build the fold line:
   * 1. Add the cmdwin_type for the command-line window
   * 2. Add the 'foldcolumn'
   * 3. Add the 'number' or 'relativenumber' column
   * 4. Compose the text
   * 5. Add the text
   * 6. set highlighting for the Visual area an other text
   */
  col = 0;

  /*
   * 1. Add the cmdwin_type for the command-line window
   * Ignores 'rightleft', this window is never right-left.
   */
  if (cmdwin_type != 0 && wp == curwin) {
    ScreenLines[off] = cmdwin_type;
    ScreenAttrs[off] = hl_attr(HLF_AT);
    if (enc_utf8)
      ScreenLinesUC[off] = 0;
    ++col;
  }

  /*
   * 2. Add the 'foldcolumn'
   */
  fdc = wp->w_p_fdc;
  if (fdc > wp->w_width - col)
    fdc = wp->w_width - col;
  if (fdc > 0) {
    fill_foldcolumn(buf, wp, TRUE, lnum);
    if (wp->w_p_rl) {
      int i;

      copy_text_attr(off + wp->w_width - fdc - col, buf, fdc,
          hl_attr(HLF_FC));
      /* reverse the fold column */
      for (i = 0; i < fdc; ++i)
        ScreenLines[off + wp->w_width - i - 1 - col] = buf[i];
    } else
      copy_text_attr(off + col, buf, fdc, hl_attr(HLF_FC));
    col += fdc;
  }

# define RL_MEMSET(p, v, l)  if (wp->w_p_rl) \
    for (ri = 0; ri < l; ++ri) \
      ScreenAttrs[off + (wp->w_width - (p) - (l)) + ri] = v; \
  else \
    for (ri = 0; ri < l; ++ri) \
      ScreenAttrs[off + (p) + ri] = v

  /* Set all attributes of the 'number' or 'relativenumber' column and the
   * text */
  RL_MEMSET(col, hl_attr(HLF_FL), wp->w_width - col);

  /* If signs are being displayed, add two spaces. */
  if (draw_signcolumn(wp)) {
      len = wp->w_width - col;
      if (len > 0) {
          if (len > 2) {
              len = 2;
          }
          copy_text_attr(off + col, (char_u *)"  ", len, hl_attr(HLF_FL));
          col += len;
      }
  }

  /*
   * 3. Add the 'number' or 'relativenumber' column
   */
  if (wp->w_p_nu || wp->w_p_rnu) {
    len = wp->w_width - col;
    if (len > 0) {
      int w = number_width(wp);
      long num;
      char *fmt = "%*ld ";

      if (len > w + 1)
        len = w + 1;

      if (wp->w_p_nu && !wp->w_p_rnu)
        /* 'number' + 'norelativenumber' */
        num = (long)lnum;
      else {
        /* 'relativenumber', don't use negative numbers */
        num = labs((long)get_cursor_rel_lnum(wp, lnum));
        if (num == 0 && wp->w_p_nu && wp->w_p_rnu) {
          /* 'number' + 'relativenumber': cursor line shows absolute
           * line number */
          num = lnum;
          fmt = "%-*ld ";
        }
      }

      sprintf((char *)buf, fmt, w, num);
      if (wp->w_p_rl)
        /* the line number isn't reversed */
        copy_text_attr(off + wp->w_width - len - col, buf, len,
            hl_attr(HLF_FL));
      else
        copy_text_attr(off + col, buf, len, hl_attr(HLF_FL));
      col += len;
    }
  }

  /*
   * 4. Compose the folded-line string with 'foldtext', if set.
   */
  text = get_foldtext(wp, lnum, lnume, foldinfo, buf);

  txtcol = col;         /* remember where text starts */

  /*
   * 5. move the text to current_ScreenLine.  Fill up with "fill_fold".
   *    Right-left text is put in columns 0 - number-col, normal text is put
   *    in columns number-col - window-width.
   */
  if (has_mbyte) {
    int cells;
    int u8c, u8cc[MAX_MCO];
    int i;
    int idx;
    int c_len;
    char_u  *p;
    int prev_c = 0;                     /* previous Arabic character */
    int prev_c1 = 0;                    /* first composing char for prev_c */

    if (wp->w_p_rl)
      idx = off;
    else
      idx = off + col;

    /* Store multibyte characters in ScreenLines[] et al. correctly. */
    for (p = text; *p != NUL; ) {
      cells = (*mb_ptr2cells)(p);
      c_len = (*mb_ptr2len)(p);
      if (col + cells > wp->w_width
          - (wp->w_p_rl ? col : 0)
          )
        break;
      ScreenLines[idx] = *p;
      if (enc_utf8) {
        u8c = utfc_ptr2char(p, u8cc);
        if (*p < 0x80 && u8cc[0] == 0) {
          ScreenLinesUC[idx] = 0;
          prev_c = u8c;
        } else {
          if (p_arshape && !p_tbidi && arabic_char(u8c)) {
            /* Do Arabic shaping. */
            int pc, pc1, nc;
            int pcc[MAX_MCO];
            int firstbyte = *p;

            /* The idea of what is the previous and next
             * character depends on 'rightleft'. */
            if (wp->w_p_rl) {
              pc = prev_c;
              pc1 = prev_c1;
              nc = utf_ptr2char(p + c_len);
              prev_c1 = u8cc[0];
            } else {
              pc = utfc_ptr2char(p + c_len, pcc);
              nc = prev_c;
              pc1 = pcc[0];
            }
            prev_c = u8c;

            u8c = arabic_shape(u8c, &firstbyte, &u8cc[0],
                pc, pc1, nc);
            ScreenLines[idx] = firstbyte;
          } else
            prev_c = u8c;
          /* Non-BMP character: display as ? or fullwidth ?. */
          ScreenLinesUC[idx] = u8c;
          for (i = 0; i < Screen_mco; ++i) {
            ScreenLinesC[i][idx] = u8cc[i];
            if (u8cc[i] == 0)
              break;
          }
        }
        if (cells > 1)
          ScreenLines[idx + 1] = 0;
      } else if (enc_dbcs == DBCS_JPNU && *p == 0x8e)
        /* double-byte single width character */
        ScreenLines2[idx] = p[1];
      else if (cells > 1)
        /* double-width character */
        ScreenLines[idx + 1] = p[1];
      col += cells;
      idx += cells;
      p += c_len;
    }
  } else {
    len = (int)STRLEN(text);
    if (len > wp->w_width - col)
      len = wp->w_width - col;
    if (len > 0) {
      if (wp->w_p_rl)
        STRNCPY(current_ScreenLine, text, len);
      else
        STRNCPY(current_ScreenLine + col, text, len);
      col += len;
    }
  }

  /* Fill the rest of the line with the fold filler */
  if (wp->w_p_rl)
    col -= txtcol;
  while (col < wp->w_width
         - (wp->w_p_rl ? txtcol : 0)
         ) {
    if (enc_utf8) {
      if (fill_fold >= 0x80) {
        ScreenLinesUC[off + col] = fill_fold;
        ScreenLinesC[0][off + col] = 0;
      } else
        ScreenLinesUC[off + col] = 0;
    }
    ScreenLines[off + col++] = fill_fold;
  }

  if (text != buf)
    xfree(text);

  /*
   * 6. set highlighting for the Visual area an other text.
   * If all folded lines are in the Visual area, highlight the line.
   */
  if (VIsual_active && wp->w_buffer == curwin->w_buffer) {
    if (ltoreq(curwin->w_cursor, VIsual)) {
      /* Visual is after curwin->w_cursor */
      top = &curwin->w_cursor;
      bot = &VIsual;
    } else {
      /* Visual is before curwin->w_cursor */
      top = &VIsual;
      bot = &curwin->w_cursor;
    }
    if (lnum >= top->lnum
        && lnume <= bot->lnum
        && (VIsual_mode != 'v'
            || ((lnum > top->lnum
                 || (lnum == top->lnum
                     && top->col == 0))
                && (lnume < bot->lnum
                    || (lnume == bot->lnum
                        && (bot->col - (*p_sel == 'e'))
                        >= (colnr_T)STRLEN(ml_get_buf(wp->w_buffer, lnume,
                                FALSE))))))) {
      if (VIsual_mode == Ctrl_V) {
        /* Visual block mode: highlight the chars part of the block */
        if (wp->w_old_cursor_fcol + txtcol < (colnr_T)wp->w_width) {
          if (wp->w_old_cursor_lcol != MAXCOL
              && wp->w_old_cursor_lcol + txtcol
              < (colnr_T)wp->w_width)
            len = wp->w_old_cursor_lcol;
          else
            len = wp->w_width - txtcol;
          RL_MEMSET(wp->w_old_cursor_fcol + txtcol, hl_attr(HLF_V),
              len - (int)wp->w_old_cursor_fcol);
        }
      } else {
        /* Set all attributes of the text */
        RL_MEMSET(txtcol, hl_attr(HLF_V), wp->w_width - txtcol);
      }
    }
  }

  /* Show 'cursorcolumn' in the fold line. */
  if (wp->w_p_cuc) {
    txtcol += wp->w_virtcol;
    if (wp->w_p_wrap)
      txtcol -= wp->w_skipcol;
    else
      txtcol -= wp->w_leftcol;
    if (txtcol >= 0 && txtcol < wp->w_width)
      ScreenAttrs[off + txtcol] = hl_combine_attr(
          ScreenAttrs[off + txtcol], hl_attr(HLF_CUC));
  }

  SCREEN_LINE(row + wp->w_winrow, wp->w_wincol, wp->w_width,
              wp->w_width, FALSE);

  /*
   * Update w_cline_height and w_cline_folded if the cursor line was
   * updated (saves a call to plines() later).
   */
  if (wp == curwin
      && lnum <= curwin->w_cursor.lnum
      && lnume >= curwin->w_cursor.lnum) {
    curwin->w_cline_row = row;
    curwin->w_cline_height = 1;
    curwin->w_cline_folded = TRUE;
    curwin->w_valid |= (VALID_CHEIGHT|VALID_CROW);
  }
}

/*
 * Copy "buf[len]" to ScreenLines["off"] and set attributes to "attr".
 */
static void copy_text_attr(int off, char_u *buf, int len, int attr)
{
  int i;

  memmove(ScreenLines + off, buf, (size_t)len);
  if (enc_utf8)
    memset(ScreenLinesUC + off, 0, sizeof(u8char_T) * (size_t)len);
  for (i = 0; i < len; ++i)
    ScreenAttrs[off + i] = attr;
}

/*
 * Fill the foldcolumn at "p" for window "wp".
 * Only to be called when 'foldcolumn' > 0.
 */
static void
fill_foldcolumn (
    char_u *p,
    win_T *wp,
    int closed,                     /* TRUE of FALSE */
    linenr_T lnum                  /* current line number */
)
{
  int i = 0;
  int level;
  int first_level;
  int empty;

  /* Init to all spaces. */
  memset(p, ' ', (size_t)wp->w_p_fdc);

  level = win_foldinfo.fi_level;
  if (level > 0) {
    /* If there is only one column put more info in it. */
    empty = (wp->w_p_fdc == 1) ? 0 : 1;

    /* If the column is too narrow, we start at the lowest level that
     * fits and use numbers to indicated the depth. */
    first_level = level - wp->w_p_fdc - closed + 1 + empty;
    if (first_level < 1)
      first_level = 1;

    for (i = 0; i + empty < wp->w_p_fdc; ++i) {
      if (win_foldinfo.fi_lnum == lnum
          && first_level + i >= win_foldinfo.fi_low_level)
        p[i] = '-';
      else if (first_level == 1)
        p[i] = '|';
      else if (first_level + i <= 9)
        p[i] = '0' + first_level + i;
      else
        p[i] = '>';
      if (first_level + i == level)
        break;
    }
  }
  if (closed)
    p[i >= wp->w_p_fdc ? i - 1 : i] = '+';
}

/*
 * Display line "lnum" of window 'wp' on the screen.
 * Start at row "startrow", stop when "endrow" is reached.
 * wp->w_virtcol needs to be valid.
 *
 * Return the number of last row the line occupies.
 */
static int
win_line (
    win_T *wp,
    linenr_T lnum,
    int startrow,
    int endrow,
    bool nochange                    /* not updating for changed text */
)
{
  int col;                              /* visual column on screen */
  unsigned off;                         /* offset in ScreenLines/ScreenAttrs */
  int c = 0;                            /* init for GCC */
  long vcol = 0;                        /* virtual column (for tabs) */
  long vcol_sbr = -1;                   // virtual column after showbreak
  long vcol_prev = -1;                  /* "vcol" of previous character */
  char_u      *line;                    /* current line */
  char_u      *ptr;                     /* current position in "line" */
  int row;                              /* row in the window, excl w_winrow */
  int screen_row;                       /* row on the screen, incl w_winrow */

  char_u extra[18];                     /* line number and 'fdc' must fit in here */
  int n_extra = 0;                      /* number of extra chars */
  char_u      *p_extra = NULL;          /* string of extra chars, plus NUL */
  char_u      *p_extra_free = NULL;     /* p_extra needs to be freed */
  int c_extra = NUL;                    /* extra chars, all the same */
  int extra_attr = 0;                   /* attributes when n_extra != 0 */
  static char_u *at_end_str = (char_u *)"";   /* used for p_extra when
                                                 displaying lcs_eol at end-of-line */
  int lcs_eol_one = lcs_eol;            /* lcs_eol until it's been used */
  int lcs_prec_todo = lcs_prec;             /* lcs_prec until it's been used */

  /* saved "extra" items for when draw_state becomes WL_LINE (again) */
  int saved_n_extra = 0;
  char_u      *saved_p_extra = NULL;
  int saved_c_extra = 0;
  int saved_char_attr = 0;

  int n_attr = 0;                       /* chars with special attr */
  int saved_attr2 = 0;                  /* char_attr saved for n_attr */
  int n_attr3 = 0;                      /* chars with overruling special attr */
  int saved_attr3 = 0;                  /* char_attr saved for n_attr3 */

  int n_skip = 0;                       /* nr of chars to skip for 'nowrap' */

  int fromcol, tocol;                   /* start/end of inverting */
  int fromcol_prev = -2;                /* start of inverting after cursor */
  int noinvcur = FALSE;                 /* don't invert the cursor */
  pos_T       *top, *bot;
  int lnum_in_visual_area = FALSE;
  pos_T pos;
  long v;

  int char_attr = 0;                    /* attributes for next character */
  int attr_pri = FALSE;                 /* char_attr has priority */
  int area_highlighting = FALSE;           /* Visual or incsearch highlighting
                                              in this line */
  int attr = 0;                         /* attributes for area highlighting */
  int area_attr = 0;                    /* attributes desired by highlighting */
  int search_attr = 0;                  /* attributes desired by 'hlsearch' */
  int vcol_save_attr = 0;               /* saved attr for 'cursorcolumn' */
  int syntax_attr = 0;                  /* attributes desired by syntax */
  int has_syntax = FALSE;               /* this buffer has syntax highl. */
  int save_did_emsg;
  int eol_hl_off = 0;                   /* 1 if highlighted char after EOL */
  int draw_color_col = FALSE;           /* highlight colorcolumn */
  int         *color_cols = NULL;       /* pointer to according columns array */
  bool has_spell = false;               /* this buffer has spell checking */
# define SPWORDLEN 150
  char_u nextline[SPWORDLEN * 2];       /* text with start of the next line */
  int nextlinecol = 0;                  /* column where nextline[] starts */
  int nextline_idx = 0;                 /* index in nextline[] where next line
                                           starts */
  int spell_attr = 0;                   /* attributes desired by spelling */
  int word_end = 0;                     /* last byte with same spell_attr */
  static linenr_T checked_lnum = 0;     /* line number for "checked_col" */
  static int checked_col = 0;           /* column in "checked_lnum" up to which
                                         * there are no spell errors */
  static int cap_col = -1;              /* column to check for Cap word */
  static linenr_T capcol_lnum = 0;      /* line number where "cap_col" used */
  int cur_checked_col = 0;              /* checked column for current line */
  int extra_check;                      /* has syntax or linebreak */
  int multi_attr = 0;                   /* attributes desired by multibyte */
  int mb_l = 1;                         /* multi-byte byte length */
  int mb_c = 0;                         /* decoded multi-byte character */
  int mb_utf8 = FALSE;                  /* screen char is UTF-8 char */
  int u8cc[MAX_MCO];                    /* composing UTF-8 chars */
  int filler_lines;                     /* nr of filler lines to be drawn */
  int filler_todo;                      /* nr of filler lines still to do + 1 */
  hlf_T diff_hlf = (hlf_T)0;            /* type of diff highlighting */
  int change_start = MAXCOL;            /* first col of changed area */
  int change_end = -1;                  /* last col of changed area */
  colnr_T trailcol = MAXCOL;            /* start of trailing spaces */
  int need_showbreak = FALSE;
  int line_attr = 0;                    /* attribute for the whole line */
  matchitem_T *cur;                     /* points to the match list */
  match_T     *shl;                     /* points to search_hl or a match */
  int shl_flag;                         /* flag to indicate whether search_hl
                                           has been processed or not */
  int prevcol_hl_flag;                  /* flag to indicate whether prevcol
                                           equals startcol of search_hl or one
                                           of the matches */
  int prev_c = 0;                       /* previous Arabic character */
  int prev_c1 = 0;                      /* first composing char for prev_c */
  int did_line_attr = 0;

  /* draw_state: items that are drawn in sequence: */
#define WL_START        0               /* nothing done yet */
# define WL_CMDLINE     WL_START + 1    /* cmdline window column */
# define WL_FOLD        WL_CMDLINE + 1  /* 'foldcolumn' */
# define WL_SIGN        WL_FOLD + 1     /* column for signs */
#define WL_NR           WL_SIGN + 1     /* line number */
# define WL_BRI         WL_NR + 1       /* 'breakindent' */
# define WL_SBR         WL_BRI + 1       /* 'showbreak' or 'diff' */
#define WL_LINE         WL_SBR + 1      /* text in the line */
  int draw_state = WL_START;            /* what to draw next */

  int syntax_flags    = 0;
  int syntax_seqnr    = 0;
  int prev_syntax_id  = 0;
  int conceal_attr    = hl_attr(HLF_CONCEAL);
  int is_concealing   = FALSE;
  int boguscols       = 0;              /* nonexistent columns added to force
                                           wrapping */
  int vcol_off        = 0;              /* offset for concealed characters */
  int did_wcol        = FALSE;
  int old_boguscols = 0;
# define VCOL_HLC (vcol - vcol_off)
# define FIX_FOR_BOGUSCOLS \
  { \
    n_extra += vcol_off; \
    vcol -= vcol_off; \
    vcol_off = 0; \
    col -= boguscols; \
    old_boguscols = boguscols; \
    boguscols = 0; \
  }

  if (startrow > endrow)                /* past the end already! */
    return startrow;

  row = startrow;
  screen_row = row + wp->w_winrow;

  /*
   * To speed up the loop below, set extra_check when there is linebreak,
   * trailing white space and/or syntax processing to be done.
   */
  extra_check = wp->w_p_lbr;
  if (syntax_present(wp) && !wp->w_s->b_syn_error) {
    /* Prepare for syntax highlighting in this line.  When there is an
     * error, stop syntax highlighting. */
    save_did_emsg = did_emsg;
    did_emsg = FALSE;
    syntax_start(wp, lnum);
    if (did_emsg)
      wp->w_s->b_syn_error = TRUE;
    else {
      did_emsg = save_did_emsg;
      has_syntax = TRUE;
      extra_check = TRUE;
    }
  }

  /* Check for columns to display for 'colorcolumn'. */
  color_cols = wp->w_buffer->terminal ? NULL : wp->w_p_cc_cols;
  if (color_cols != NULL)
    draw_color_col = advance_color_col(VCOL_HLC, &color_cols);

  if (wp->w_p_spell
      && *wp->w_s->b_p_spl != NUL
      && !GA_EMPTY(&wp->w_s->b_langp)
      && *(char **)(wp->w_s->b_langp.ga_data) != NULL) {
    /* Prepare for spell checking. */
    has_spell = true;
    extra_check = TRUE;

    /* Get the start of the next line, so that words that wrap to the next
     * line are found too: "et<line-break>al.".
     * Trick: skip a few chars for C/shell/Vim comments */
    nextline[SPWORDLEN] = NUL;
    if (lnum < wp->w_buffer->b_ml.ml_line_count) {
      line = ml_get_buf(wp->w_buffer, lnum + 1, FALSE);
      spell_cat_line(nextline + SPWORDLEN, line, SPWORDLEN);
    }

    /* When a word wrapped from the previous line the start of the current
     * line is valid. */
    if (lnum == checked_lnum)
      cur_checked_col = checked_col;
    checked_lnum = 0;

    /* When there was a sentence end in the previous line may require a
     * word starting with capital in this line.  In line 1 always check
     * the first word. */
    if (lnum != capcol_lnum)
      cap_col = -1;
    if (lnum == 1)
      cap_col = 0;
    capcol_lnum = 0;
  }

  /*
   * handle visual active in this window
   */
  fromcol = -10;
  tocol = MAXCOL;
  if (VIsual_active && wp->w_buffer == curwin->w_buffer) {
    /* Visual is after curwin->w_cursor */
    if (ltoreq(curwin->w_cursor, VIsual)) {
      top = &curwin->w_cursor;
      bot = &VIsual;
    } else {                          /* Visual is before curwin->w_cursor */
      top = &VIsual;
      bot = &curwin->w_cursor;
    }
    lnum_in_visual_area = (lnum >= top->lnum && lnum <= bot->lnum);
    if (VIsual_mode == Ctrl_V) {        /* block mode */
      if (lnum_in_visual_area) {
        fromcol = wp->w_old_cursor_fcol;
        tocol = wp->w_old_cursor_lcol;
      }
    } else {                          /* non-block mode */
      if (lnum > top->lnum && lnum <= bot->lnum)
        fromcol = 0;
      else if (lnum == top->lnum) {
        if (VIsual_mode == 'V')         /* linewise */
          fromcol = 0;
        else {
          getvvcol(wp, top, (colnr_T *)&fromcol, NULL, NULL);
          if (gchar_pos(top) == NUL)
            tocol = fromcol + 1;
        }
      }
      if (VIsual_mode != 'V' && lnum == bot->lnum) {
        if (*p_sel == 'e' && bot->col == 0
            && bot->coladd == 0
            ) {
          fromcol = -10;
          tocol = MAXCOL;
        } else if (bot->col == MAXCOL)
          tocol = MAXCOL;
        else {
          pos = *bot;
          if (*p_sel == 'e')
            getvvcol(wp, &pos, (colnr_T *)&tocol, NULL, NULL);
          else {
            getvvcol(wp, &pos, NULL, NULL, (colnr_T *)&tocol);
            ++tocol;
          }
        }
      }
    }

    /* Check if the character under the cursor should not be inverted */
    if (!highlight_match && lnum == curwin->w_cursor.lnum && wp == curwin
        )
      noinvcur = TRUE;

    /* if inverting in this line set area_highlighting */
    if (fromcol >= 0) {
      area_highlighting = TRUE;
      attr = hl_attr(HLF_V);
    }
  }
  /*
   * handle 'incsearch' and ":s///c" highlighting
   */
  else if (highlight_match
           && wp == curwin
           && lnum >= curwin->w_cursor.lnum
           && lnum <= curwin->w_cursor.lnum + search_match_lines) {
    if (lnum == curwin->w_cursor.lnum)
      getvcol(curwin, &(curwin->w_cursor),
          (colnr_T *)&fromcol, NULL, NULL);
    else
      fromcol = 0;
    if (lnum == curwin->w_cursor.lnum + search_match_lines) {
      pos.lnum = lnum;
      pos.col = search_match_endcol;
      getvcol(curwin, &pos, (colnr_T *)&tocol, NULL, NULL);
    } else
      tocol = MAXCOL;
    /* do at least one character; happens when past end of line */
    if (fromcol == tocol)
      tocol = fromcol + 1;
    area_highlighting = TRUE;
    attr = hl_attr(HLF_I);
  }

  filler_lines = diff_check(wp, lnum);
  if (filler_lines < 0) {
    if (filler_lines == -1) {
      if (diff_find_change(wp, lnum, &change_start, &change_end))
        diff_hlf = HLF_ADD;             /* added line */
      else if (change_start == 0)
        diff_hlf = HLF_TXD;             /* changed text */
      else
        diff_hlf = HLF_CHD;             /* changed line */
    } else
      diff_hlf = HLF_ADD;               /* added line */
    filler_lines = 0;
    area_highlighting = TRUE;
  }
  if (lnum == wp->w_topline)
    filler_lines = wp->w_topfill;
  filler_todo = filler_lines;

  /* If this line has a sign with line highlighting set line_attr. */
  v = buf_getsigntype(wp->w_buffer, lnum, SIGN_LINEHL);
  if (v != 0)
      line_attr = sign_get_attr((int)v, TRUE);

  /* Highlight the current line in the quickfix window. */
  if (bt_quickfix(wp->w_buffer) && qf_current_entry(wp) == lnum)
    line_attr = hl_attr(HLF_L);
  if (line_attr != 0)
    area_highlighting = TRUE;

  line = ml_get_buf(wp->w_buffer, lnum, FALSE);
  ptr = line;

  if (has_spell) {
    /* For checking first word with a capital skip white space. */
    if (cap_col == 0)
      cap_col = (int)(skipwhite(line) - line);

    /* To be able to spell-check over line boundaries copy the end of the
     * current line into nextline[].  Above the start of the next line was
     * copied to nextline[SPWORDLEN]. */
    if (nextline[SPWORDLEN] == NUL) {
      /* No next line or it is empty. */
      nextlinecol = MAXCOL;
      nextline_idx = 0;
    } else {
      v = (long)STRLEN(line);
      if (v < SPWORDLEN) {
        /* Short line, use it completely and append the start of the
         * next line. */
        nextlinecol = 0;
        memmove(nextline, line, (size_t)v);
        STRMOVE(nextline + v, nextline + SPWORDLEN);
        nextline_idx = v + 1;
      } else {
        /* Long line, use only the last SPWORDLEN bytes. */
        nextlinecol = v - SPWORDLEN;
        memmove(nextline, line + nextlinecol, SPWORDLEN);
        nextline_idx = SPWORDLEN + 1;
      }
    }
  }

  /* find start of trailing whitespace */
  if (wp->w_p_list && lcs_trail) {
    trailcol = (colnr_T)STRLEN(ptr);
    while (trailcol > (colnr_T)0 && ascii_iswhite(ptr[trailcol - 1]))
      --trailcol;
    trailcol += (colnr_T) (ptr - line);
    extra_check = TRUE;
  }

  /*
   * 'nowrap' or 'wrap' and a single line that doesn't fit: Advance to the
   * first character to be displayed.
   */
  if (wp->w_p_wrap)
    v = wp->w_skipcol;
  else
    v = wp->w_leftcol;
  if (v > 0) {
    char_u  *prev_ptr = ptr;
    while (vcol < v && *ptr != NUL) {
      c = win_lbr_chartabsize(wp, line, ptr, (colnr_T)vcol, NULL);
      vcol += c;
      prev_ptr = ptr;
      mb_ptr_adv(ptr);
    }

    /* When:
     * - 'cuc' is set, or
     * - 'colorcolumn' is set, or
     * - 'virtualedit' is set, or
     * - the visual mode is active,
     * the end of the line may be before the start of the displayed part.
     */
    if (vcol < v && (
          wp->w_p_cuc
          || draw_color_col
          ||
          virtual_active()
          ||
          (VIsual_active && wp->w_buffer == curwin->w_buffer)
          )) {
      vcol = v;
    }

    /* Handle a character that's not completely on the screen: Put ptr at
     * that character but skip the first few screen characters. */
    if (vcol > v) {
      vcol -= c;
      ptr = prev_ptr;
      n_skip = v - vcol;
    }

    /*
     * Adjust for when the inverted text is before the screen,
     * and when the start of the inverted text is before the screen.
     */
    if (tocol <= vcol)
      fromcol = 0;
    else if (fromcol >= 0 && fromcol < vcol)
      fromcol = vcol;

    /* When w_skipcol is non-zero, first line needs 'showbreak' */
    if (wp->w_p_wrap)
      need_showbreak = TRUE;
    /* When spell checking a word we need to figure out the start of the
     * word and if it's badly spelled or not. */
    if (has_spell) {
      size_t len;
      colnr_T linecol = (colnr_T)(ptr - line);
      hlf_T spell_hlf = HLF_COUNT;

      pos = wp->w_cursor;
      wp->w_cursor.lnum = lnum;
      wp->w_cursor.col = linecol;
      len = spell_move_to(wp, FORWARD, TRUE, TRUE, &spell_hlf);

      /* spell_move_to() may call ml_get() and make "line" invalid */
      line = ml_get_buf(wp->w_buffer, lnum, FALSE);
      ptr = line + linecol;

      if (len == 0 || (int)wp->w_cursor.col > ptr - line) {
        /* no bad word found at line start, don't check until end of a
         * word */
        spell_hlf = HLF_COUNT;
        word_end = (int)(spell_to_word_end(ptr, wp) - line + 1);
      } else {
        /* bad word found, use attributes until end of word */
        assert(len <= INT_MAX);
        word_end = wp->w_cursor.col + (int)len + 1;

        /* Turn index into actual attributes. */
        if (spell_hlf != HLF_COUNT)
          spell_attr = highlight_attr[spell_hlf];
      }
      wp->w_cursor = pos;

      /* Need to restart syntax highlighting for this line. */
      if (has_syntax)
        syntax_start(wp, lnum);
    }
  }

  /*
   * Correct highlighting for cursor that can't be disabled.
   * Avoids having to check this for each character.
   */
  if (fromcol >= 0) {
    if (noinvcur) {
      if ((colnr_T)fromcol == wp->w_virtcol) {
        /* highlighting starts at cursor, let it start just after the
         * cursor */
        fromcol_prev = fromcol;
        fromcol = -1;
      } else if ((colnr_T)fromcol < wp->w_virtcol)
        /* restart highlighting after the cursor */
        fromcol_prev = wp->w_virtcol;
    }
    if (fromcol >= tocol)
      fromcol = -1;
  }

  /*
   * Handle highlighting the last used search pattern and matches.
   * Do this for both search_hl and the match list.
   */
  cur = wp->w_match_head;
  shl_flag = FALSE;
  while (cur != NULL || shl_flag == FALSE) {
    if (shl_flag == FALSE) {
      shl = &search_hl;
      shl_flag = TRUE;
    } else
      shl = &cur->hl;
    shl->startcol = MAXCOL;
    shl->endcol = MAXCOL;
    shl->attr_cur = 0;
    v = (long)(ptr - line);
    if (cur != NULL) {
      cur->pos.cur = 0;
    }
    next_search_hl(wp, shl, lnum, (colnr_T)v, cur);

    // Need to get the line again, a multi-line regexp may have made it
    // invalid.
    line = ml_get_buf(wp->w_buffer, lnum, false);
    ptr = line + v;

    if (shl->lnum != 0 && shl->lnum <= lnum) {
      if (shl->lnum == lnum) {
        shl->startcol = shl->rm.startpos[0].col;
      } else {
        shl->startcol = 0;
      }
      if (lnum == shl->lnum + shl->rm.endpos[0].lnum
                  - shl->rm.startpos[0].lnum) {
          shl->endcol = shl->rm.endpos[0].col;
      } else {
          shl->endcol = MAXCOL;
      }
      // Highlight one character for an empty match.
      if (shl->startcol == shl->endcol) {
          if (has_mbyte && line[shl->endcol] != NUL) {
              shl->endcol += (*mb_ptr2len)(line + shl->endcol);
          } else {
              ++shl->endcol;
          }
      }
      if ((long)shl->startcol < v) {   // match at leftcol
        shl->attr_cur = shl->attr;
        search_attr = shl->attr;
      }
      area_highlighting = true;
    }
    if (shl != &search_hl && cur != NULL)
      cur = cur->next;
  }

  /* Cursor line highlighting for 'cursorline' in the current window.  Not
   * when Visual mode is active, because it's not clear what is selected
   * then. */
  if (wp->w_p_cul && lnum == wp->w_cursor.lnum
      && !(wp == curwin && VIsual_active)) {
    line_attr = hl_attr(HLF_CUL);
    area_highlighting = true;
  }

  off = (unsigned)(current_ScreenLine - ScreenLines);
  col = 0;
  if (wp->w_p_rl) {
    /* Rightleft window: process the text in the normal direction, but put
     * it in current_ScreenLine[] from right to left.  Start at the
     * rightmost column of the window. */
    col = wp->w_width - 1;
    off += col;
  }

  // wont highlight after 1024 columns
  int term_attrs[1024] = {0};
  if (wp->w_buffer->terminal) {
    terminal_get_line_attributes(wp->w_buffer->terminal, wp, lnum, term_attrs);
    extra_check = true;
  }

  /*
   * Repeat for the whole displayed line.
   */
  for (;; ) {
    /* Skip this quickly when working on the text. */
    if (draw_state != WL_LINE) {
      if (draw_state == WL_CMDLINE - 1 && n_extra == 0) {
        draw_state = WL_CMDLINE;
        if (cmdwin_type != 0 && wp == curwin) {
          /* Draw the cmdline character. */
          n_extra = 1;
          c_extra = cmdwin_type;
          char_attr = hl_attr(HLF_AT);
        }
      }

      if (draw_state == WL_FOLD - 1 && n_extra == 0) {
        draw_state = WL_FOLD;
        if (wp->w_p_fdc > 0) {
          /* Draw the 'foldcolumn'. */
          fill_foldcolumn(extra, wp, FALSE, lnum);
          n_extra = wp->w_p_fdc;
          p_extra = extra;
          p_extra[n_extra] = NUL;
          c_extra = NUL;
          char_attr = hl_attr(HLF_FC);
        }
      }

      //sign column
      if (draw_state == WL_SIGN - 1 && n_extra == 0) {
          draw_state = WL_SIGN;
          /* Show the sign column when there are any signs in this
           * buffer or when using Netbeans. */
          if (draw_signcolumn(wp)) {
              int text_sign;
              /* Draw two cells with the sign value or blank. */
              c_extra = ' ';
              char_attr = hl_attr(HLF_SC);
              n_extra = 2;

              if (row == startrow + filler_lines && filler_todo <= 0) {
                  text_sign = buf_getsigntype(wp->w_buffer, lnum, SIGN_TEXT);
                  if (text_sign != 0) {
                      p_extra = sign_get_text(text_sign);
                      if (p_extra != NULL) {
                          c_extra = NUL;
                          n_extra = (int)STRLEN(p_extra);
                      }
                      char_attr = sign_get_attr(text_sign, FALSE);
                  }
              }
          }
      }

      if (draw_state == WL_NR - 1 && n_extra == 0) {
        draw_state = WL_NR;
        /* Display the absolute or relative line number. After the
         * first fill with blanks when the 'n' flag isn't in 'cpo' */
        if ((wp->w_p_nu || wp->w_p_rnu)
            && (row == startrow
                + filler_lines
                || vim_strchr(p_cpo, CPO_NUMCOL) == NULL)) {
          /* Draw the line number (empty space after wrapping). */
          if (row == startrow
              + filler_lines
              ) {
            long num;
            char *fmt = "%*ld ";

            if (wp->w_p_nu && !wp->w_p_rnu)
              /* 'number' + 'norelativenumber' */
              num = (long)lnum;
            else {
              /* 'relativenumber', don't use negative numbers */
              num = labs((long)get_cursor_rel_lnum(wp, lnum));
              if (num == 0 && wp->w_p_nu && wp->w_p_rnu) {
                /* 'number' + 'relativenumber' */
                num = lnum;
                fmt = "%-*ld ";
              }
            }

            sprintf((char *)extra, fmt,
                number_width(wp), num);
            if (wp->w_skipcol > 0)
              for (p_extra = extra; *p_extra == ' '; ++p_extra)
                *p_extra = '-';
            if (wp->w_p_rl)                         /* reverse line numbers */
              rl_mirror(extra);
            p_extra = extra;
            c_extra = NUL;
          } else
            c_extra = ' ';
          n_extra = number_width(wp) + 1;
          char_attr = hl_attr(HLF_N);
          /* When 'cursorline' is set highlight the line number of
           * the current line differently.
           * TODO: Can we use CursorLine instead of CursorLineNr
           * when CursorLineNr isn't set? */
          if ((wp->w_p_cul || wp->w_p_rnu)
              && lnum == wp->w_cursor.lnum)
            char_attr = hl_attr(HLF_CLN);
        }
      }

      if (wp->w_p_brisbr && draw_state == WL_BRI - 1
          && n_extra == 0 && *p_sbr != NUL) {
        // draw indent after showbreak value
        draw_state = WL_BRI;
      } else if (wp->w_p_brisbr && draw_state == WL_SBR && n_extra == 0) {
        // after the showbreak, draw the breakindent
        draw_state = WL_BRI - 1;
      }

      // draw 'breakindent': indent wrapped text accodringly
      if (draw_state == WL_BRI - 1 && n_extra == 0) {
        draw_state = WL_BRI;
        if (wp->w_p_bri && n_extra == 0 && row != startrow && filler_lines == 0) {
          char_attr = 0; // was: hl_attr(HLF_AT);

          if (diff_hlf != (hlf_T)0) {
            char_attr = hl_attr(diff_hlf);
            if (wp->w_p_cul && lnum == wp->w_cursor.lnum) {
              char_attr = hl_combine_attr(char_attr, hl_attr(HLF_CUL));
            }
          }
          p_extra = NULL;
          c_extra = ' ';
          n_extra = get_breakindent_win(wp, ml_get_buf(wp->w_buffer, lnum, FALSE));
          /* Correct end of highlighted area for 'breakindent',
             required wen 'linebreak' is also set. */
          if (tocol == vcol)
            tocol += n_extra;
        }
      }

      if (draw_state == WL_SBR - 1 && n_extra == 0) {
        draw_state = WL_SBR;
        if (filler_todo > 0) {
          /* Draw "deleted" diff line(s). */
          if (char2cells(fill_diff) > 1)
            c_extra = '-';
          else
            c_extra = fill_diff;
          if (wp->w_p_rl)
            n_extra = col + 1;
          else
            n_extra = wp->w_width - col;
          char_attr = hl_attr(HLF_DED);
        }
        if (*p_sbr != NUL && need_showbreak) {
          /* Draw 'showbreak' at the start of each broken line. */
          p_extra = p_sbr;
          c_extra = NUL;
          n_extra = (int)STRLEN(p_sbr);
          char_attr = hl_attr(HLF_AT);
          need_showbreak = FALSE;
          vcol_sbr = vcol + MB_CHARLEN(p_sbr);
          /* Correct end of highlighted area for 'showbreak',
           * required when 'linebreak' is also set. */
          if (tocol == vcol)
            tocol += n_extra;
          /* combine 'showbreak' with 'cursorline' */
          if (wp->w_p_cul && lnum == wp->w_cursor.lnum) {
            char_attr = hl_combine_attr(char_attr, hl_attr(HLF_CUL));
          }
        }
      }

      if (draw_state == WL_LINE - 1 && n_extra == 0) {
        draw_state = WL_LINE;
        if (saved_n_extra) {
          /* Continue item from end of wrapped line. */
          n_extra = saved_n_extra;
          c_extra = saved_c_extra;
          p_extra = saved_p_extra;
          char_attr = saved_char_attr;
        } else
          char_attr = 0;
      }
    }

    /* When still displaying '$' of change command, stop at cursor */
    if (dollar_vcol >= 0 && wp == curwin
        && lnum == wp->w_cursor.lnum && vcol >= (long)wp->w_virtcol
        && filler_todo <= 0
        ) {
      SCREEN_LINE(screen_row, wp->w_wincol, col, -wp->w_width, wp->w_p_rl);
      /* Pretend we have finished updating the window.  Except when
       * 'cursorcolumn' is set. */
      if (wp->w_p_cuc)
        row = wp->w_cline_row + wp->w_cline_height;
      else
        row = wp->w_height;
      break;
    }

    if (draw_state == WL_LINE && area_highlighting) {
      /* handle Visual or match highlighting in this line */
      if (vcol == fromcol
          || (has_mbyte && vcol + 1 == fromcol && n_extra == 0
              && (*mb_ptr2cells)(ptr) > 1)
          || ((int)vcol_prev == fromcol_prev
              && vcol_prev < vcol               /* not at margin */
              && vcol < tocol))
        area_attr = attr;                       /* start highlighting */
      else if (area_attr != 0
               && (vcol == tocol
                   || (noinvcur && (colnr_T)vcol == wp->w_virtcol)))
        area_attr = 0;                          /* stop highlighting */

      if (!n_extra) {
        /*
         * Check for start/end of search pattern match.
         * After end, check for start/end of next match.
         * When another match, have to check for start again.
         * Watch out for matching an empty string!
         * Do this for 'search_hl' and the match list (ordered by
         * priority).
         */
        v = (long)(ptr - line);
        cur = wp->w_match_head;
        shl_flag = FALSE;
        while (cur != NULL || shl_flag == FALSE) {
          if (shl_flag == FALSE
              && ((cur != NULL
                   && cur->priority > SEARCH_HL_PRIORITY)
                  || cur == NULL)) {
            shl = &search_hl;
            shl_flag = TRUE;
          } else
            shl = &cur->hl;
          if (cur != NULL) {
            cur->pos.cur = 0;
          }
          bool pos_inprogress = true; // mark that a position match search is
                                      // in progress
          while (shl->rm.regprog != NULL
                                 || (cur != NULL && pos_inprogress)) {
            if (shl->startcol != MAXCOL
                && v >= (long)shl->startcol
                && v < (long)shl->endcol) {
              int tmp_col = v + MB_PTR2LEN(ptr);

              if (shl->endcol < tmp_col) {
                shl->endcol = tmp_col;
              }
              shl->attr_cur = shl->attr;
            } else if (v == (long)shl->endcol) {
              shl->attr_cur = 0;

              next_search_hl(wp, shl, lnum, (colnr_T)v, cur);
              pos_inprogress = !(cur == NULL || cur->pos.cur == 0);

              /* Need to get the line again, a multi-line regexp
               * may have made it invalid. */
              line = ml_get_buf(wp->w_buffer, lnum, FALSE);
              ptr = line + v;

              if (shl->lnum == lnum) {
                shl->startcol = shl->rm.startpos[0].col;
                if (shl->rm.endpos[0].lnum == 0)
                  shl->endcol = shl->rm.endpos[0].col;
                else
                  shl->endcol = MAXCOL;

                if (shl->startcol == shl->endcol) {
                  /* highlight empty match, try again after
                   * it */
                  if (has_mbyte)
                    shl->endcol += (*mb_ptr2len)(line
                                                 + shl->endcol);
                  else
                    ++shl->endcol;
                }

                /* Loop to check if the match starts at the
                 * current position */
                continue;
              }
            }
            break;
          }
          if (shl != &search_hl && cur != NULL)
            cur = cur->next;
        }

        /* Use attributes from match with highest priority among
         * 'search_hl' and the match list. */
        search_attr = search_hl.attr_cur;
        cur = wp->w_match_head;
        shl_flag = FALSE;
        while (cur != NULL || shl_flag == FALSE) {
          if (shl_flag == FALSE
              && ((cur != NULL
                   && cur->priority > SEARCH_HL_PRIORITY)
                  || cur == NULL)) {
            shl = &search_hl;
            shl_flag = TRUE;
          } else
            shl = &cur->hl;
          if (shl->attr_cur != 0)
            search_attr = shl->attr_cur;
          if (shl != &search_hl && cur != NULL)
            cur = cur->next;
        }
      }

      if (diff_hlf != (hlf_T)0) {
        if (diff_hlf == HLF_CHD && ptr - line >= change_start
            && n_extra == 0)
          diff_hlf = HLF_TXD;                   /* changed text */
        if (diff_hlf == HLF_TXD && ptr - line > change_end
            && n_extra == 0)
          diff_hlf = HLF_CHD;                   /* changed line */
        line_attr = hl_attr(diff_hlf);
        if (wp->w_p_cul && lnum == wp->w_cursor.lnum) {
          line_attr = hl_combine_attr(line_attr, hl_attr(HLF_CUL));
        }
      }

      /* Decide which of the highlight attributes to use. */
      attr_pri = TRUE;
      if (area_attr != 0)
        char_attr = area_attr;
      else if (search_attr != 0)
        char_attr = search_attr;
      /* Use line_attr when not in the Visual or 'incsearch' area
       * (area_attr may be 0 when "noinvcur" is set). */
      else if (line_attr != 0 && ((fromcol == -10 && tocol == MAXCOL)
                                  || vcol < fromcol || vcol_prev < fromcol_prev
                                  || vcol >= tocol))
        char_attr = line_attr;
      else {
        attr_pri = FALSE;
        if (has_syntax)
          char_attr = syntax_attr;
        else
          char_attr = 0;
      }
    }

    /*
     * Get the next character to put on the screen.
     */
    /*
     * The "p_extra" points to the extra stuff that is inserted to
     * represent special characters (non-printable stuff) and other
     * things.  When all characters are the same, c_extra is used.
     * "p_extra" must end in a NUL to avoid mb_ptr2len() reads past
     * "p_extra[n_extra]".
     * For the '$' of the 'list' option, n_extra == 1, p_extra == "".
     */
    if (n_extra > 0) {
      if (c_extra != NUL) {
        c = c_extra;
        mb_c = c;               /* doesn't handle non-utf-8 multi-byte! */
        if (enc_utf8 && (*mb_char2len)(c) > 1) {
          mb_utf8 = TRUE;
          u8cc[0] = 0;
          c = 0xc0;
        } else
          mb_utf8 = FALSE;
      } else {
        c = *p_extra;
        if (has_mbyte) {
          mb_c = c;
          if (enc_utf8) {
            /* If the UTF-8 character is more than one byte:
             * Decode it into "mb_c". */
            mb_l = (*mb_ptr2len)(p_extra);
            mb_utf8 = FALSE;
            if (mb_l > n_extra)
              mb_l = 1;
            else if (mb_l > 1) {
              mb_c = utfc_ptr2char(p_extra, u8cc);
              mb_utf8 = TRUE;
              c = 0xc0;
            }
          } else {
            /* if this is a DBCS character, put it in "mb_c" */
            mb_l = MB_BYTE2LEN(c);
            if (mb_l >= n_extra)
              mb_l = 1;
            else if (mb_l > 1)
              mb_c = (c << 8) + p_extra[1];
          }
          if (mb_l == 0)            /* at the NUL at end-of-line */
            mb_l = 1;

          /* If a double-width char doesn't fit display a '>' in the
           * last column. */
          if ((
                wp->w_p_rl ? (col <= 0) :
                (col >= wp->w_width - 1))
              && (*mb_char2cells)(mb_c) == 2) {
            c = '>';
            mb_c = c;
            mb_l = 1;
            mb_utf8 = FALSE;
            multi_attr = hl_attr(HLF_AT);
            /* put the pointer back to output the double-width
             * character at the start of the next line. */
            ++n_extra;
            --p_extra;
          } else {
            n_extra -= mb_l - 1;
            p_extra += mb_l - 1;
          }
        }
        ++p_extra;
      }
      --n_extra;
    } else {
      if (p_extra_free != NULL) {
        xfree(p_extra_free);
        p_extra_free = NULL;
      }
      /*
       * Get a character from the line itself.
       */
      c = *ptr;
      if (has_mbyte) {
        mb_c = c;
        if (enc_utf8) {
          /* If the UTF-8 character is more than one byte: Decode it
           * into "mb_c". */
          mb_l = (*mb_ptr2len)(ptr);
          mb_utf8 = FALSE;
          if (mb_l > 1) {
            mb_c = utfc_ptr2char(ptr, u8cc);
            /* Overlong encoded ASCII or ASCII with composing char
             * is displayed normally, except a NUL. */
            if (mb_c < 0x80)
              c = mb_c;
            mb_utf8 = TRUE;

            /* At start of the line we can have a composing char.
             * Draw it as a space with a composing char. */
            if (utf_iscomposing(mb_c)) {
              int i;

              for (i = Screen_mco - 1; i > 0; --i)
                u8cc[i] = u8cc[i - 1];
              u8cc[0] = mb_c;
              mb_c = ' ';
            }
          }

          if ((mb_l == 1 && c >= 0x80)
              || (mb_l >= 1 && mb_c == 0)
              || (mb_l > 1 && (!vim_isprintc(mb_c)))) {
            // Illegal UTF-8 byte: display as <xx>.
            // Non-BMP character : display as ? or fullwidth ?.
            transchar_hex(extra, mb_c);
            if (wp->w_p_rl) {                         // reverse
                rl_mirror(extra);
            }

            p_extra = extra;
            c = *p_extra;
            mb_c = mb_ptr2char_adv(&p_extra);
            mb_utf8 = (c >= 0x80);
            n_extra = (int)STRLEN(p_extra);
            c_extra = NUL;
            if (area_attr == 0 && search_attr == 0) {
              n_attr = n_extra + 1;
              extra_attr = hl_attr(HLF_8);
              saved_attr2 = char_attr;               /* save current attr */
            }
          } else if (mb_l == 0)          /* at the NUL at end-of-line */
            mb_l = 1;
          else if (p_arshape && !p_tbidi && arabic_char(mb_c)) {
            /* Do Arabic shaping. */
            int pc, pc1, nc;
            int pcc[MAX_MCO];

            /* The idea of what is the previous and next
             * character depends on 'rightleft'. */
            if (wp->w_p_rl) {
              pc = prev_c;
              pc1 = prev_c1;
              nc = utf_ptr2char(ptr + mb_l);
              prev_c1 = u8cc[0];
            } else {
              pc = utfc_ptr2char(ptr + mb_l, pcc);
              nc = prev_c;
              pc1 = pcc[0];
            }
            prev_c = mb_c;

            mb_c = arabic_shape(mb_c, &c, &u8cc[0], pc, pc1, nc);
          } else
            prev_c = mb_c;
        } else {      /* enc_dbcs */
          mb_l = MB_BYTE2LEN(c);
          if (mb_l == 0)            /* at the NUL at end-of-line */
            mb_l = 1;
          else if (mb_l > 1) {
            /* We assume a second byte below 32 is illegal.
             * Hopefully this is OK for all double-byte encodings!
             */
            if (ptr[1] >= 32)
              mb_c = (c << 8) + ptr[1];
            else {
              if (ptr[1] == NUL) {
                /* head byte at end of line */
                mb_l = 1;
                transchar_nonprint(extra, c);
              } else {
                /* illegal tail byte */
                mb_l = 2;
                STRCPY(extra, "XX");
              }
              p_extra = extra;
              n_extra = (int)STRLEN(extra) - 1;
              c_extra = NUL;
              c = *p_extra++;
              if (area_attr == 0 && search_attr == 0) {
                n_attr = n_extra + 1;
                extra_attr = hl_attr(HLF_8);
                saved_attr2 = char_attr;                 /* save current attr */
              }
              mb_c = c;
            }
          }
        }
        /* If a double-width char doesn't fit display a '>' in the
         * last column; the character is displayed at the start of the
         * next line. */
        if ((
              wp->w_p_rl ? (col <= 0) :
              (col >= wp->w_width - 1))
            && (*mb_char2cells)(mb_c) == 2) {
          c = '>';
          mb_c = c;
          mb_utf8 = FALSE;
          mb_l = 1;
          multi_attr = hl_attr(HLF_AT);
          /* Put pointer back so that the character will be
           * displayed at the start of the next line. */
          --ptr;
        } else if (*ptr != NUL)
          ptr += mb_l - 1;

        /* If a double-width char doesn't fit at the left side display
         * a '<' in the first column.  Don't do this for unprintable
         * characters. */
        if (n_skip > 0 && mb_l > 1 && n_extra == 0) {
          n_extra = 1;
          c_extra = MB_FILLER_CHAR;
          c = ' ';
          if (area_attr == 0 && search_attr == 0) {
            n_attr = n_extra + 1;
            extra_attr = hl_attr(HLF_AT);
            saved_attr2 = char_attr;             /* save current attr */
          }
          mb_c = c;
          mb_utf8 = FALSE;
          mb_l = 1;
        }

      }
      ++ptr;

      // 'list': change char 160 to lcs_nbsp and space to lcs_space.
      if (wp->w_p_list
          && (((c == 160 || (mb_utf8 && mb_c == 160)) && lcs_nbsp)
              || (c == ' ' && lcs_space && ptr - line <=  trailcol))) {
        c = (c == ' ') ? lcs_space : lcs_nbsp;
        if (area_attr == 0 && search_attr == 0) {
          n_attr = 1;
          extra_attr = hl_attr(HLF_8);
          saved_attr2 = char_attr;           /* save current attr */
        }
        mb_c = c;
        if (enc_utf8 && (*mb_char2len)(c) > 1) {
          mb_utf8 = TRUE;
          u8cc[0] = 0;
          c = 0xc0;
        } else
          mb_utf8 = FALSE;
      }

      if (extra_check) {
        bool can_spell = true;

        /* Get syntax attribute, unless still at the start of the line
         * (double-wide char that doesn't fit). */
        v = (long)(ptr - line);
        if (has_syntax && v > 0) {
          /* Get the syntax attribute for the character.  If there
           * is an error, disable syntax highlighting. */
          save_did_emsg = did_emsg;
          did_emsg = FALSE;

          syntax_attr = get_syntax_attr((colnr_T)v - 1,
              has_spell ? &can_spell :
              NULL, FALSE);

          if (did_emsg) {
            wp->w_s->b_syn_error = TRUE;
            has_syntax = FALSE;
          } else
            did_emsg = save_did_emsg;

          /* Need to get the line again, a multi-line regexp may
           * have made it invalid. */
          line = ml_get_buf(wp->w_buffer, lnum, FALSE);
          ptr = line + v;

          if (!attr_pri)
            char_attr = syntax_attr;
          else
            char_attr = hl_combine_attr(syntax_attr, char_attr);
          /* no concealing past the end of the line, it interferes
           * with line highlighting */
          if (c == NUL)
            syntax_flags = 0;
          else
            syntax_flags = get_syntax_info(&syntax_seqnr);
        } else if (!attr_pri) {
          char_attr = 0;
        }

        /* Check spelling (unless at the end of the line).
         * Only do this when there is no syntax highlighting, the
         * @Spell cluster is not used or the current syntax item
         * contains the @Spell cluster. */
        if (has_spell && v >= word_end && v > cur_checked_col) {
          spell_attr = 0;
          if (!attr_pri)
            char_attr = syntax_attr;
          if (c != 0 && (
                !has_syntax ||
                can_spell)) {
            char_u  *prev_ptr, *p;
            int len;
            hlf_T spell_hlf = HLF_COUNT;
            if (has_mbyte) {
              prev_ptr = ptr - mb_l;
              v -= mb_l - 1;
            } else
              prev_ptr = ptr - 1;

            /* Use nextline[] if possible, it has the start of the
             * next line concatenated. */
            if ((prev_ptr - line) - nextlinecol >= 0)
              p = nextline + (prev_ptr - line) - nextlinecol;
            else
              p = prev_ptr;
            cap_col -= (int)(prev_ptr - line);
            size_t tmplen = spell_check(wp, p, &spell_hlf, &cap_col, nochange);
            assert(tmplen <= INT_MAX);
            len = (int)tmplen;
            word_end = v + len;

            /* In Insert mode only highlight a word that
             * doesn't touch the cursor. */
            if (spell_hlf != HLF_COUNT
                && (State & INSERT) != 0
                && wp->w_cursor.lnum == lnum
                && wp->w_cursor.col >=
                (colnr_T)(prev_ptr - line)
                && wp->w_cursor.col < (colnr_T)word_end) {
              spell_hlf = HLF_COUNT;
              spell_redraw_lnum = lnum;
            }

            if (spell_hlf == HLF_COUNT && p != prev_ptr
                && (p - nextline) + len > nextline_idx) {
              /* Remember that the good word continues at the
               * start of the next line. */
              checked_lnum = lnum + 1;
              checked_col = (int)((p - nextline) + len - nextline_idx);
            }

            /* Turn index into actual attributes. */
            if (spell_hlf != HLF_COUNT)
              spell_attr = highlight_attr[spell_hlf];

            if (cap_col > 0) {
              if (p != prev_ptr
                  && (p - nextline) + cap_col >= nextline_idx) {
                /* Remember that the word in the next line
                 * must start with a capital. */
                capcol_lnum = lnum + 1;
                cap_col = (int)((p - nextline) + cap_col
                                - nextline_idx);
              } else
                /* Compute the actual column. */
                cap_col += (int)(prev_ptr - line);
            }
          }
        }
        if (spell_attr != 0) {
          if (!attr_pri)
            char_attr = hl_combine_attr(char_attr, spell_attr);
          else
            char_attr = hl_combine_attr(spell_attr, char_attr);
        }

        if (wp->w_buffer->terminal) {
          char_attr = hl_combine_attr(char_attr, term_attrs[vcol]);
        }

        /*
         * Found last space before word: check for line break.
         */
        if (wp->w_p_lbr && vim_isbreak(c) && !vim_isbreak(*ptr)) {
          char_u *p = ptr - (
              has_mbyte ? mb_l :
              1);
          // TODO: is passing p for start of the line OK?
          n_extra = win_lbr_chartabsize(wp, line, p, (colnr_T)vcol, NULL) - 1;
          if (c == TAB && n_extra + col > wp->w_width) {
            n_extra = (int)wp->w_buffer->b_p_ts
                      - vcol % (int)wp->w_buffer->b_p_ts - 1;
          }
          c_extra = ' ';
          if (ascii_iswhite(c)) {
            if (c == TAB)
              /* See "Tab alignment" below. */
              FIX_FOR_BOGUSCOLS;
            if (!wp->w_p_list) {
              c = ' ';
            }
          }
        }

        if (trailcol != MAXCOL && ptr > line + trailcol && c == ' ') {
          c = lcs_trail;
          if (!attr_pri) {
            n_attr = 1;
            extra_attr = hl_attr(HLF_8);
            saved_attr2 = char_attr;             /* save current attr */
          }
          mb_c = c;
          if (enc_utf8 && (*mb_char2len)(c) > 1) {
            mb_utf8 = TRUE;
            u8cc[0] = 0;
            c = 0xc0;
          } else
            mb_utf8 = FALSE;
        }
      }

      /*
       * Handling of non-printable characters.
       */
      if (!(chartab[c & 0xff] & CT_PRINT_CHAR)) {
        /*
         * when getting a character from the file, we may have to
         * turn it into something else on the way to putting it
         * into "ScreenLines".
         */
        if (c == TAB && (!wp->w_p_list || lcs_tab1)) {
          int tab_len = 0;
          long vcol_adjusted = vcol;  // removed showbreak length
          // Only adjust the tab_len, when at the first column after the
          // showbreak value was drawn.
          if (*p_sbr != NUL && vcol == vcol_sbr && wp->w_p_wrap) {
            vcol_adjusted = vcol - MB_CHARLEN(p_sbr);
          }
          // tab amount depends on current column
          tab_len = (int)wp->w_buffer->b_p_ts
                    - vcol_adjusted % (int)wp->w_buffer->b_p_ts - 1;

          if (!wp->w_p_lbr || !wp->w_p_list) {
            n_extra = tab_len;
          } else {
            char_u *p;
            int    i;
            int    saved_nextra = n_extra;

            if ((is_concealing || boguscols > 0) && vcol_off > 0) {
              // there are characters to conceal
              tab_len += vcol_off;
            }
            // boguscols before FIX_FOR_BOGUSCOLS macro from above.
            if (wp->w_p_list && lcs_tab1 && old_boguscols > 0
                && n_extra > tab_len) {
              tab_len += n_extra - tab_len;
            }

            /* if n_extra > 0, it gives the number of chars to use for
             * a tab, else we need to calculate the width for a tab */
            int len = (tab_len * mb_char2len(lcs_tab2));
            if (n_extra > 0) {
              len += n_extra - tab_len;
            }
            c = lcs_tab1;
            p = xmalloc(len + 1);
            memset(p, ' ', len);
            p[len] = NUL;
            p_extra_free = p;
            for (i = 0; i < tab_len; i++) {
              mb_char2bytes(lcs_tab2, p);
              p += mb_char2len(lcs_tab2);
              n_extra += mb_char2len(lcs_tab2) - (saved_nextra > 0 ? 1: 0);
            }
            p_extra = p_extra_free;

            // n_extra will be increased by FIX_FOX_BOGUSCOLS
            // macro below, so need to adjust for that here
            if ((is_concealing || boguscols > 0) && vcol_off > 0) {
              n_extra -= vcol_off;
            }
          }
          /* Tab alignment should be identical regardless of
           * 'conceallevel' value. So tab compensates of all
           * previous concealed characters, and thus resets vcol_off
           * and boguscols accumulated so far in the line. Note that
           * the tab can be longer than 'tabstop' when there
           * are concealed characters. */
          FIX_FOR_BOGUSCOLS;
          // Make sure that the highlighting for the tab char will be correctly
          // set further below (effectively reverts the FIX_FOR_BOGSUCOLS
          // macro).
          if (old_boguscols > 0 && n_extra > tab_len && wp->w_p_list
              && lcs_tab1) {
            tab_len += n_extra - tab_len;
          }
          mb_utf8 = FALSE;              /* don't draw as UTF-8 */
          if (wp->w_p_list) {
            c = lcs_tab1;
            if (wp->w_p_lbr) {
              c_extra = NUL; /* using p_extra from above */
            } else {
              c_extra = lcs_tab2;
            }
            n_attr = tab_len + 1;
            extra_attr = hl_attr(HLF_8);
            saved_attr2 = char_attr;             /* save current attr */
            mb_c = c;
            if (enc_utf8 && (*mb_char2len)(c) > 1) {
              mb_utf8 = TRUE;
              u8cc[0] = 0;
              c = 0xc0;
            }
          } else {
            c_extra = ' ';
            c = ' ';
          }
        } else if (c == NUL
                   && ((wp->w_p_list && lcs_eol > 0)
                       || ((fromcol >= 0 || fromcol_prev >= 0)
                           && tocol > vcol
                           && VIsual_mode != Ctrl_V
                           && (
                             wp->w_p_rl ? (col >= 0) :
                             (col < wp->w_width))
                           && !(noinvcur
                                && lnum == wp->w_cursor.lnum
                                && (colnr_T)vcol == wp->w_virtcol)))
                   && lcs_eol_one >= 0) {
          /* Display a '$' after the line or highlight an extra
           * character if the line break is included. */
          /* For a diff line the highlighting continues after the
           * "$". */
          if (diff_hlf == (hlf_T)0 && line_attr == 0) {
            /* In virtualedit, visual selections may extend
             * beyond end of line. */
            if (area_highlighting && virtual_active()
                && tocol != MAXCOL && vcol < tocol)
              n_extra = 0;
            else {
              p_extra = at_end_str;
              n_extra = 1;
              c_extra = NUL;
            }
          }
          if (wp->w_p_list)
            c = lcs_eol;
          else
            c = ' ';
          lcs_eol_one = -1;
          --ptr;                    /* put it back at the NUL */
          if (!attr_pri) {
            extra_attr = hl_attr(HLF_AT);
            n_attr = 1;
          }
          mb_c = c;
          if (enc_utf8 && (*mb_char2len)(c) > 1) {
            mb_utf8 = TRUE;
            u8cc[0] = 0;
            c = 0xc0;
          } else
            mb_utf8 = FALSE;                    /* don't draw as UTF-8 */
        } else if (c != NUL) {
          p_extra = transchar(c);
          if (n_extra == 0) {
              n_extra = byte2cells(c) - 1;
          }
          if ((dy_flags & DY_UHEX) && wp->w_p_rl)
            rl_mirror(p_extra);                 /* reverse "<12>" */
          c_extra = NUL;
          if (wp->w_p_lbr) {
            char_u *p;

            c = *p_extra;
            p = xmalloc(n_extra + 1);
            memset(p, ' ', n_extra);
            STRNCPY(p, p_extra + 1, STRLEN(p_extra) - 1);
            p[n_extra] = NUL;
            p_extra_free = p_extra = p;
          } else {
            n_extra = byte2cells(c) - 1;
            c = *p_extra++;
          }
          if (!attr_pri) {
            n_attr = n_extra + 1;
            extra_attr = hl_attr(HLF_8);
            saved_attr2 = char_attr;             /* save current attr */
          }
          mb_utf8 = FALSE;              /* don't draw as UTF-8 */
        } else if (VIsual_active
                   && (VIsual_mode == Ctrl_V
                       || VIsual_mode == 'v')
                   && virtual_active()
                   && tocol != MAXCOL
                   && vcol < tocol
                   && (
                     wp->w_p_rl ? (col >= 0) :
                     (col < wp->w_width))) {
          c = ' ';
          --ptr;                    /* put it back at the NUL */
        } else if ((
                   diff_hlf != (hlf_T)0 ||
                   line_attr != 0
                   ) && (
                   wp->w_p_rl ? (col >= 0) :
                   (col
                    - boguscols
                    < wp->w_width))) {
          /* Highlight until the right side of the window */
          c = ' ';
          --ptr;                    /* put it back at the NUL */

          /* Remember we do the char for line highlighting. */
          ++did_line_attr;

          /* don't do search HL for the rest of the line */
          if (line_attr != 0 && char_attr == search_attr && col > 0)
            char_attr = line_attr;
          if (diff_hlf == HLF_TXD) {
            diff_hlf = HLF_CHD;
            if (attr == 0 || char_attr != attr) {
              char_attr = hl_attr(diff_hlf);
              if (wp->w_p_cul && lnum == wp->w_cursor.lnum) {
                char_attr = hl_combine_attr(char_attr, hl_attr(HLF_CUL));
              }
            }
          }
        }
      }

      if (   wp->w_p_cole > 0
             && (wp != curwin || lnum != wp->w_cursor.lnum ||
                 conceal_cursor_line(wp))
             && (syntax_flags & HL_CONCEAL) != 0
             && !(lnum_in_visual_area
                  && vim_strchr(wp->w_p_cocu, 'v') == NULL)) {
        char_attr = conceal_attr;
        if (prev_syntax_id != syntax_seqnr
            && (syn_get_sub_char() != NUL || wp->w_p_cole == 1)
            && wp->w_p_cole != 3) {
          /* First time at this concealed item: display one
           * character. */
          if (syn_get_sub_char() != NUL)
            c = syn_get_sub_char();
          else if (lcs_conceal != NUL)
            c = lcs_conceal;
          else
            c = ' ';

          prev_syntax_id = syntax_seqnr;

          if (n_extra > 0)
            vcol_off += n_extra;
          vcol += n_extra;
          if (wp->w_p_wrap && n_extra > 0) {
            if (wp->w_p_rl) {
              col -= n_extra;
              boguscols -= n_extra;
            } else {
              boguscols += n_extra;
              col += n_extra;
            }
          }
          n_extra = 0;
          n_attr = 0;
        } else if (n_skip == 0) {
          is_concealing = TRUE;
          n_skip = 1;
        }
        mb_c = c;
        if (enc_utf8 && (*mb_char2len)(c) > 1) {
          mb_utf8 = TRUE;
          u8cc[0] = 0;
          c = 0xc0;
        } else
          mb_utf8 = FALSE;              /* don't draw as UTF-8 */
      } else {
        prev_syntax_id = 0;
        is_concealing = FALSE;
      }
    }

    /* In the cursor line and we may be concealing characters: correct
     * the cursor column when we reach its position. */
    if (!did_wcol && draw_state == WL_LINE
        && wp == curwin && lnum == wp->w_cursor.lnum
        && conceal_cursor_line(wp)
        && (int)wp->w_virtcol <= vcol + n_skip) {
      wp->w_wcol = col - boguscols;
      wp->w_wrow = row;
      did_wcol = TRUE;
    }

    /* Don't override visual selection highlighting. */
    if (n_attr > 0
        && draw_state == WL_LINE
        && !attr_pri)
      char_attr = extra_attr;

    /*
     * Handle the case where we are in column 0 but not on the first
     * character of the line and the user wants us to show us a
     * special character (via 'listchars' option "precedes:<char>".
     */
    if (lcs_prec_todo != NUL
        && wp->w_p_list
        && (wp->w_p_wrap ? wp->w_skipcol > 0 : wp->w_leftcol > 0)
        && filler_todo <= 0
        && draw_state > WL_NR
        && c != NUL) {
      c = lcs_prec;
      lcs_prec_todo = NUL;
      if (has_mbyte && (*mb_char2cells)(mb_c) > 1) {
        /* Double-width character being overwritten by the "precedes"
         * character, need to fill up half the character. */
        c_extra = MB_FILLER_CHAR;
        n_extra = 1;
        n_attr = 2;
        extra_attr = hl_attr(HLF_AT);
      }
      mb_c = c;
      if (enc_utf8 && (*mb_char2len)(c) > 1) {
        mb_utf8 = TRUE;
        u8cc[0] = 0;
        c = 0xc0;
      } else
        mb_utf8 = FALSE;                /* don't draw as UTF-8 */
      if (!attr_pri) {
        saved_attr3 = char_attr;         /* save current attr */
        char_attr = hl_attr(HLF_AT);         /* later copied to char_attr */
        n_attr3 = 1;
      }
    }

    /*
     * At end of the text line or just after the last character.
     */
    if (c == NUL || did_line_attr == 1) {
      long prevcol = (long)(ptr - line) - (c == NUL);

      /* we're not really at that column when skipping some text */
      if ((long)(wp->w_p_wrap ? wp->w_skipcol : wp->w_leftcol) > prevcol)
        ++prevcol;

      /* Invert at least one char, used for Visual and empty line or
       * highlight match at end of line. If it's beyond the last
       * char on the screen, just overwrite that one (tricky!)  Not
       * needed when a '$' was displayed for 'list'. */
      prevcol_hl_flag = FALSE;
      if (prevcol == (long)search_hl.startcol)
        prevcol_hl_flag = TRUE;
      else {
        cur = wp->w_match_head;
        while (cur != NULL) {
          if (prevcol == (long)cur->hl.startcol) {
            prevcol_hl_flag = TRUE;
            break;
          }
          cur = cur->next;
        }
      }
      if (lcs_eol == lcs_eol_one
          && ((area_attr != 0 && vcol == fromcol
               && (VIsual_mode != Ctrl_V
                   || lnum == VIsual.lnum
                   || lnum == curwin->w_cursor.lnum)
               && c == NUL)
              /* highlight 'hlsearch' match at end of line */
              || (prevcol_hl_flag == TRUE && did_line_attr <= 1)
              )) {
        int n = 0;

        if (wp->w_p_rl) {
          if (col < 0)
            n = 1;
        } else {
          if (col >= wp->w_width)
            n = -1;
        }
        if (n != 0) {
          /* At the window boundary, highlight the last character
           * instead (better than nothing). */
          off += n;
          col += n;
        } else {
          /* Add a blank character to highlight. */
          ScreenLines[off] = ' ';
          if (enc_utf8)
            ScreenLinesUC[off] = 0;
        }
        if (area_attr == 0) {
          /* Use attributes from match with highest priority among
           * 'search_hl' and the match list. */
          char_attr = search_hl.attr;
          cur = wp->w_match_head;
          shl_flag = FALSE;
          while (cur != NULL || shl_flag == FALSE) {
            if (shl_flag == FALSE
                && ((cur != NULL
                     && cur->priority > SEARCH_HL_PRIORITY)
                    || cur == NULL)) {
              shl = &search_hl;
              shl_flag = TRUE;
            } else
              shl = &cur->hl;
            if ((ptr - line) - 1 == (long)shl->startcol)
              char_attr = shl->attr;
            if (shl != &search_hl && cur != NULL)
              cur = cur->next;
          }
        }
        ScreenAttrs[off] = char_attr;
        if (wp->w_p_rl) {
          --col;
          --off;
        } else {
          ++col;
          ++off;
        }
        ++vcol;
        eol_hl_off = 1;
      }
    }

    /*
     * At end of the text line.
     */
    if (c == NUL) {
      if (eol_hl_off > 0 && vcol - eol_hl_off == (long)wp->w_virtcol
          && lnum == wp->w_cursor.lnum) {
        /* highlight last char after line */
        --col;
        --off;
        --vcol;
      }

      /* Highlight 'cursorcolumn' & 'colorcolumn' past end of the line. */
      if (wp->w_p_wrap)
        v = wp->w_skipcol;
      else
        v = wp->w_leftcol;

      /* check if line ends before left margin */
      if (vcol < v + col - win_col_off(wp))
        vcol = v + col - win_col_off(wp);
      /* Get rid of the boguscols now, we want to draw until the right
       * edge for 'cursorcolumn'. */
      col -= boguscols;
      // boguscols = 0;  // Disabled because value never read after this

      if (draw_color_col)
        draw_color_col = advance_color_col(VCOL_HLC, &color_cols);

      if (((wp->w_p_cuc
            && (int)wp->w_virtcol >= VCOL_HLC - eol_hl_off
            && (int)wp->w_virtcol <
            wp->w_width * (row - startrow + 1) + v
            && lnum != wp->w_cursor.lnum)
           || draw_color_col)
          && !wp->w_p_rl
          ) {
        int rightmost_vcol = 0;
        int i;

        if (wp->w_p_cuc)
          rightmost_vcol = wp->w_virtcol;
        if (draw_color_col)
          /* determine rightmost colorcolumn to possibly draw */
          for (i = 0; color_cols[i] >= 0; ++i)
            if (rightmost_vcol < color_cols[i])
              rightmost_vcol = color_cols[i];

        while (col < wp->w_width) {
          ScreenLines[off] = ' ';
          if (enc_utf8)
            ScreenLinesUC[off] = 0;
          ++col;
          if (draw_color_col)
            draw_color_col = advance_color_col(VCOL_HLC,
                &color_cols);

          if (wp->w_p_cuc && VCOL_HLC == (long)wp->w_virtcol)
            ScreenAttrs[off++] = hl_attr(HLF_CUC);
          else if (draw_color_col && VCOL_HLC == *color_cols)
            ScreenAttrs[off++] = hl_attr(HLF_MC);
          else
            ScreenAttrs[off++] = 0;

          if (VCOL_HLC >= rightmost_vcol)
            break;

          ++vcol;
        }
      }

      if (wp->w_buffer->terminal) {
        // terminal buffers may need to highlight beyond the end of the
        // logical line
        while (col < wp->w_width) {
          ScreenLines[off] = ' ';
          if (enc_utf8) {
            ScreenLinesUC[off] = 0;
          }
          ScreenAttrs[off++] = term_attrs[vcol++];
          col++;
        }
      }
      SCREEN_LINE(screen_row, wp->w_wincol, col, wp->w_width, wp->w_p_rl);
      row++;

      /*
       * Update w_cline_height and w_cline_folded if the cursor line was
       * updated (saves a call to plines() later).
       */
      if (wp == curwin && lnum == curwin->w_cursor.lnum) {
        curwin->w_cline_row = startrow;
        curwin->w_cline_height = row - startrow;
        curwin->w_cline_folded = FALSE;
        curwin->w_valid |= (VALID_CHEIGHT|VALID_CROW);
      }

      break;
    }

    /* line continues beyond line end */
    if (lcs_ext
        && !wp->w_p_wrap
        && filler_todo <= 0
        && (
          wp->w_p_rl ? col == 0 :
          col == wp->w_width - 1)
        && (*ptr != NUL
            || (wp->w_p_list && lcs_eol_one > 0)
            || (n_extra && (c_extra != NUL || *p_extra != NUL)))) {
      c = lcs_ext;
      char_attr = hl_attr(HLF_AT);
      mb_c = c;
      if (enc_utf8 && (*mb_char2len)(c) > 1) {
        mb_utf8 = TRUE;
        u8cc[0] = 0;
        c = 0xc0;
      } else
        mb_utf8 = FALSE;
    }

    /* advance to the next 'colorcolumn' */
    if (draw_color_col)
      draw_color_col = advance_color_col(VCOL_HLC, &color_cols);

    /* Highlight the cursor column if 'cursorcolumn' is set.  But don't
     * highlight the cursor position itself.
     * Also highlight the 'colorcolumn' if it is different than
     * 'cursorcolumn' */
    vcol_save_attr = -1;
    if (draw_state == WL_LINE && !lnum_in_visual_area) {
      if (wp->w_p_cuc && VCOL_HLC == (long)wp->w_virtcol
          && lnum != wp->w_cursor.lnum) {
        vcol_save_attr = char_attr;
        char_attr = hl_combine_attr(char_attr, hl_attr(HLF_CUC));
      } else if (draw_color_col && VCOL_HLC == *color_cols) {
        vcol_save_attr = char_attr;
        char_attr = hl_combine_attr(char_attr, hl_attr(HLF_MC));
      }
    }

    /*
     * Store character to be displayed.
     * Skip characters that are left of the screen for 'nowrap'.
     */
    vcol_prev = vcol;
    if (draw_state < WL_LINE || n_skip <= 0) {
      /*
       * Store the character.
       */
      if (has_mbyte && wp->w_p_rl && (*mb_char2cells)(mb_c) > 1) {
        /* A double-wide character is: put first halve in left cell. */
        --off;
        --col;
      }
      ScreenLines[off] = c;
      if (enc_dbcs == DBCS_JPNU) {
        if ((mb_c & 0xff00) == 0x8e00)
          ScreenLines[off] = 0x8e;
        ScreenLines2[off] = mb_c & 0xff;
      } else if (enc_utf8) {
        if (mb_utf8) {
          int i;

          ScreenLinesUC[off] = mb_c;
          if ((c & 0xff) == 0)
            ScreenLines[off] = 0x80;               /* avoid storing zero */
          for (i = 0; i < Screen_mco; ++i) {
            ScreenLinesC[i][off] = u8cc[i];
            if (u8cc[i] == 0)
              break;
          }
        } else
          ScreenLinesUC[off] = 0;
      }
      if (multi_attr) {
        ScreenAttrs[off] = multi_attr;
        multi_attr = 0;
      } else
        ScreenAttrs[off] = char_attr;

      if (has_mbyte && (*mb_char2cells)(mb_c) > 1) {
        /* Need to fill two screen columns. */
        ++off;
        ++col;
        if (enc_utf8)
          /* UTF-8: Put a 0 in the second screen char. */
          ScreenLines[off] = 0;
        else
          /* DBCS: Put second byte in the second screen char. */
          ScreenLines[off] = mb_c & 0xff;
        ++vcol;
        /* When "tocol" is halfway through a character, set it to the end of
         * the character, otherwise highlighting won't stop. */
        if (tocol == vcol)
          ++tocol;
        if (wp->w_p_rl) {
          /* now it's time to backup one cell */
          --off;
          --col;
        }
      }
      if (wp->w_p_rl) {
        --off;
        --col;
      } else {
        ++off;
        ++col;
      }
    } else if (wp->w_p_cole > 0 && is_concealing) {
      --n_skip;
      ++vcol_off;
      if (n_extra > 0)
        vcol_off += n_extra;
      if (wp->w_p_wrap) {
        /*
         * Special voodoo required if 'wrap' is on.
         *
         * Advance the column indicator to force the line
         * drawing to wrap early. This will make the line
         * take up the same screen space when parts are concealed,
         * so that cursor line computations aren't messed up.
         *
         * To avoid the fictitious advance of 'col' causing
         * trailing junk to be written out of the screen line
         * we are building, 'boguscols' keeps track of the number
         * of bad columns we have advanced.
         */
        if (n_extra > 0) {
          vcol += n_extra;
          if (wp->w_p_rl) {
            col -= n_extra;
            boguscols -= n_extra;
          } else {
            col += n_extra;
            boguscols += n_extra;
          }
          n_extra = 0;
          n_attr = 0;
        }


        if (has_mbyte && (*mb_char2cells)(mb_c) > 1) {
          /* Need to fill two screen columns. */
          if (wp->w_p_rl) {
            --boguscols;
            --col;
          } else {
            ++boguscols;
            ++col;
          }
        }

        if (wp->w_p_rl) {
          --boguscols;
          --col;
        } else {
          ++boguscols;
          ++col;
        }
      } else {
        if (n_extra > 0) {
          vcol += n_extra;
          n_extra = 0;
          n_attr = 0;
        }
      }

    } else
      --n_skip;

    /* Only advance the "vcol" when after the 'number' or 'relativenumber'
     * column. */
    if (draw_state > WL_NR
        && filler_todo <= 0
        )
      ++vcol;

    if (vcol_save_attr >= 0)
      char_attr = vcol_save_attr;

    /* restore attributes after "predeces" in 'listchars' */
    if (draw_state > WL_NR && n_attr3 > 0 && --n_attr3 == 0)
      char_attr = saved_attr3;

    /* restore attributes after last 'listchars' or 'number' char */
    if (n_attr > 0 && draw_state == WL_LINE && --n_attr == 0)
      char_attr = saved_attr2;

    /*
     * At end of screen line and there is more to come: Display the line
     * so far.  If there is no more to display it is caught above.
     */
    if ((
          wp->w_p_rl ? (col < 0) :
          (col >= wp->w_width))
        && (*ptr != NUL
            || filler_todo > 0
            || (wp->w_p_list && lcs_eol != NUL && p_extra != at_end_str)
            || (n_extra != 0 && (c_extra != NUL || *p_extra != NUL)))
        ) {
      SCREEN_LINE(screen_row, wp->w_wincol, col - boguscols,
                  wp->w_width, wp->w_p_rl);
      boguscols = 0;
      ++row;
      ++screen_row;

      /* When not wrapping and finished diff lines, or when displayed
       * '$' and highlighting until last column, break here. */
      if ((!wp->w_p_wrap
           && filler_todo <= 0
           ) || lcs_eol_one == -1)
        break;

      /* When the window is too narrow draw all "@" lines. */
      if (draw_state != WL_LINE
          && filler_todo <= 0
          ) {
        win_draw_end(wp, '@', ' ', row, wp->w_height, HLF_AT);
        draw_vsep_win(wp, row);
        row = endrow;
      }

      /* When line got too long for screen break here. */
      if (row == endrow) {
        ++row;
        break;
      }

      if (ui_current_row() == screen_row - 1
          && filler_todo <= 0
          && wp->w_width == Columns) {
        /* Remember that the line wraps, used for modeless copy. */
        LineWraps[screen_row - 1] = TRUE;

        /*
         * Special trick to make copy/paste of wrapped lines work with
         * xterm/screen: write an extra character beyond the end of
         * the line. This will work with all terminal types
         * (regardless of the xn,am settings).
         * Only do this on a fast tty.
         * Only do this if the cursor is on the current line
         * (something has been written in it).
         * Don't do this for the GUI.
         * Don't do this for double-width characters.
         * Don't do this for a window not at the right screen border.
         */
        if (!(has_mbyte
                 && ((*mb_off2cells)(LineOffset[screen_row],
                                     LineOffset[screen_row] + screen_Columns)
                     == 2
                     || (*mb_off2cells)(LineOffset[screen_row - 1]
                                        + (int)Columns - 2,
                                        LineOffset[screen_row] + screen_Columns)
                     == 2))
            ) {
          /* First make sure we are at the end of the screen line,
           * then output the same character again to let the
           * terminal know about the wrap.  If the terminal doesn't
           * auto-wrap, we overwrite the character. */
          if (ui_current_col() != wp->w_width)
            screen_char(LineOffset[screen_row - 1]
                + (unsigned)Columns - 1,
                screen_row - 1, (int)(Columns - 1));

          /* When there is a multi-byte character, just output a
           * space to keep it simple. */
          if (has_mbyte && MB_BYTE2LEN(ScreenLines[LineOffset[
                                                     screen_row -
                                                     1] + (Columns - 1)]) > 1) {
            ui_putc(' ');
          } else {
            ui_putc(ScreenLines[LineOffset[screen_row - 1] + (Columns - 1)]);
          }
          /* force a redraw of the first char on the next line */
          ScreenAttrs[LineOffset[screen_row]] = (sattr_T)-1;
        }
      }

      col = 0;
      off = (unsigned)(current_ScreenLine - ScreenLines);
      if (wp->w_p_rl) {
        col = wp->w_width - 1;          /* col is not used if breaking! */
        off += col;
      }

      /* reset the drawing state for the start of a wrapped line */
      draw_state = WL_START;
      saved_n_extra = n_extra;
      saved_p_extra = p_extra;
      saved_c_extra = c_extra;
      saved_char_attr = char_attr;
      n_extra = 0;
      lcs_prec_todo = lcs_prec;
      if (filler_todo <= 0)
        need_showbreak = TRUE;
      --filler_todo;
      /* When the filler lines are actually below the last line of the
       * file, don't draw the line itself, break here. */
      if (filler_todo == 0 && wp->w_botfill)
        break;
    }

  }     /* for every character in the line */

  /* After an empty line check first word for capital. */
  if (*skipwhite(line) == NUL) {
    capcol_lnum = lnum + 1;
    cap_col = 0;
  }

  return row;
}


/*
 * Return if the composing characters at "off_from" and "off_to" differ.
 * Only to be used when ScreenLinesUC[off_from] != 0.
 */
static int comp_char_differs(int off_from, int off_to)
{
  int i;

  for (i = 0; i < Screen_mco; ++i) {
    if (ScreenLinesC[i][off_from] != ScreenLinesC[i][off_to])
      return TRUE;
    if (ScreenLinesC[i][off_from] == 0)
      break;
  }
  return FALSE;
}

/*
 * Check whether the given character needs redrawing:
 * - the (first byte of the) character is different
 * - the attributes are different
 * - the character is multi-byte and the next byte is different
 * - the character is two cells wide and the second cell differs.
 */
static int char_needs_redraw(int off_from, int off_to, int cols)
{
  return (cols > 0
      && ((ScreenLines[off_from] != ScreenLines[off_to]
           || ScreenAttrs[off_from] != ScreenAttrs[off_to])

          || (enc_dbcs != 0
              && MB_BYTE2LEN(ScreenLines[off_from]) > 1
              && (enc_dbcs == DBCS_JPNU && ScreenLines[off_from] == 0x8e
                  ? ScreenLines2[off_from] != ScreenLines2[off_to]
                  : (cols > 1 && ScreenLines[off_from + 1]
                     != ScreenLines[off_to + 1])))
          || (enc_utf8
              && (ScreenLinesUC[off_from] != ScreenLinesUC[off_to]
                  || (ScreenLinesUC[off_from] != 0
                      && comp_char_differs(off_from, off_to))
                  || ((*mb_off2cells)(off_from, off_from + cols) > 1
                      && ScreenLines[off_from + 1]
                      != ScreenLines[off_to + 1])))));
}

/*
 * Move one "cooked" screen line to the screen, but only the characters that
 * have actually changed.  Handle insert/delete character.
 * "coloff" gives the first column on the screen for this line.
 * "endcol" gives the columns where valid characters are.
 * "clear_width" is the width of the window.  It's > 0 if the rest of the line
 * needs to be cleared, negative otherwise.
 * "rlflag" is TRUE in a rightleft window:
 *    When TRUE and "clear_width" > 0, clear columns 0 to "endcol"
 *    When FALSE and "clear_width" > 0, clear columns "endcol" to "clear_width"
 */
static void screen_line(int row, int coloff, int endcol, int clear_width, int rlflag)
{
  unsigned off_from;
  unsigned off_to;
  unsigned max_off_from;
  unsigned max_off_to;
  int col = 0;
  int hl;
  int force = FALSE;                    /* force update rest of the line */
  int redraw_this                       /* bool: does character need redraw? */
  ;
  int redraw_next;                      /* redraw_this for next character */
  int clear_next = FALSE;
  int char_cells;                       /* 1: normal char */
                                        /* 2: occupies two display cells */
# define CHAR_CELLS char_cells

  /* Check for illegal row and col, just in case. */
  if (row >= Rows)
    row = Rows - 1;
  if (endcol > Columns)
    endcol = Columns;


  off_from = (unsigned)(current_ScreenLine - ScreenLines);
  off_to = LineOffset[row] + coloff;
  max_off_from = off_from + screen_Columns;
  max_off_to = LineOffset[row] + screen_Columns;

  if (rlflag) {
    /* Clear rest first, because it's left of the text. */
    if (clear_width > 0) {
      while (col <= endcol && ScreenLines[off_to] == ' '
             && ScreenAttrs[off_to] == 0
             && (!enc_utf8 || ScreenLinesUC[off_to] == 0)
             ) {
        ++off_to;
        ++col;
      }
      if (col <= endcol)
        screen_fill(row, row + 1, col + coloff,
            endcol + coloff + 1, ' ', ' ', 0);
    }
    col = endcol + 1;
    off_to = LineOffset[row] + col + coloff;
    off_from += col;
    endcol = (clear_width > 0 ? clear_width : -clear_width);
  }

  redraw_next = char_needs_redraw(off_from, off_to, endcol - col);

  while (col < endcol) {
    if (has_mbyte && (col + 1 < endcol))
      char_cells = (*mb_off2cells)(off_from, max_off_from);
    else
      char_cells = 1;

    redraw_this = redraw_next;
    redraw_next = force || char_needs_redraw(off_from + CHAR_CELLS,
        off_to + CHAR_CELLS, endcol - col - CHAR_CELLS);


    if (redraw_this) {
      if (enc_dbcs != 0) {
        /* Check if overwriting a double-byte with a single-byte or
         * the other way around requires another character to be
         * redrawn.  For UTF-8 this isn't needed, because comparing
         * ScreenLinesUC[] is sufficient. */
        if (char_cells == 1
            && col + 1 < endcol
            && (*mb_off2cells)(off_to, max_off_to) > 1) {
          /* Writing a single-cell character over a double-cell
           * character: need to redraw the next cell. */
          ScreenLines[off_to + 1] = 0;
          redraw_next = TRUE;
        } else if (char_cells == 2
                   && col + 2 < endcol
                   && (*mb_off2cells)(off_to, max_off_to) == 1
                   && (*mb_off2cells)(off_to + 1, max_off_to) > 1) {
          /* Writing the second half of a double-cell character over
           * a double-cell character: need to redraw the second
           * cell. */
          ScreenLines[off_to + 2] = 0;
          redraw_next = TRUE;
        }

        if (enc_dbcs == DBCS_JPNU)
          ScreenLines2[off_to] = ScreenLines2[off_from];
      }
      /* When writing a single-width character over a double-width
       * character and at the end of the redrawn text, need to clear out
       * the right halve of the old character.
       * Also required when writing the right halve of a double-width
       * char over the left halve of an existing one. */
      if (has_mbyte && col + char_cells == endcol
          && ((char_cells == 1
               && (*mb_off2cells)(off_to, max_off_to) > 1)
              || (char_cells == 2
                  && (*mb_off2cells)(off_to, max_off_to) == 1
                  && (*mb_off2cells)(off_to + 1, max_off_to) > 1)))
        clear_next = TRUE;

      ScreenLines[off_to] = ScreenLines[off_from];
      if (enc_utf8) {
        ScreenLinesUC[off_to] = ScreenLinesUC[off_from];
        if (ScreenLinesUC[off_from] != 0) {
          int i;

          for (i = 0; i < Screen_mco; ++i)
            ScreenLinesC[i][off_to] = ScreenLinesC[i][off_from];
        }
      }
      if (char_cells == 2)
        ScreenLines[off_to + 1] = ScreenLines[off_from + 1];

      ScreenAttrs[off_to] = ScreenAttrs[off_from];
      /* For simplicity set the attributes of second half of a
       * double-wide character equal to the first half. */
      if (char_cells == 2)
        ScreenAttrs[off_to + 1] = ScreenAttrs[off_from];

      if (enc_dbcs != 0 && char_cells == 2)
        screen_char_2(off_to, row, col + coloff);
      else
        screen_char(off_to, row, col + coloff);
    }

    off_to += CHAR_CELLS;
    off_from += CHAR_CELLS;
    col += CHAR_CELLS;
  }

  if (clear_next) {
    /* Clear the second half of a double-wide character of which the left
     * half was overwritten with a single-wide character. */
    ScreenLines[off_to] = ' ';
    if (enc_utf8)
      ScreenLinesUC[off_to] = 0;
    screen_char(off_to, row, col + coloff);
  }

  if (clear_width > 0
      && !rlflag
      ) {

    /* blank out the rest of the line */
    while (col < clear_width && ScreenLines[off_to] == ' '
           && ScreenAttrs[off_to] == 0
           && (!enc_utf8 || ScreenLinesUC[off_to] == 0)
           ) {
      ++off_to;
      ++col;
    }
    if (col < clear_width) {
      screen_fill(row, row + 1, col + coloff, clear_width + coloff,
          ' ', ' ', 0);
      off_to += clear_width - col;
      col = clear_width;
    }
  }

  if (clear_width > 0) {
    /* For a window that's left of another, draw the separator char. */
    if (col + coloff < Columns) {
      int c;

      c = fillchar_vsep(&hl);
      if (ScreenLines[off_to] != (schar_T)c
          || (enc_utf8 && (int)ScreenLinesUC[off_to]
              != (c >= 0x80 ? c : 0))
          || ScreenAttrs[off_to] != hl) {
        ScreenLines[off_to] = c;
        ScreenAttrs[off_to] = hl;
        if (enc_utf8) {
          if (c >= 0x80) {
            ScreenLinesUC[off_to] = c;
            ScreenLinesC[0][off_to] = 0;
          } else
            ScreenLinesUC[off_to] = 0;
        }
        screen_char(off_to, row, col + coloff);
      }
    } else
      LineWraps[row] = FALSE;
  }
}

/*
 * Mirror text "str" for right-left displaying.
 * Only works for single-byte characters (e.g., numbers).
 */
void rl_mirror(char_u *str)
{
  char_u      *p1, *p2;
  int t;

  for (p1 = str, p2 = str + STRLEN(str) - 1; p1 < p2; ++p1, --p2) {
    t = *p1;
    *p1 = *p2;
    *p2 = t;
  }
}

/*
 * mark all status lines for redraw; used after first :cd
 */
void status_redraw_all(void)
{

  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    if (wp->w_status_height) {
      wp->w_redr_status = TRUE;
      redraw_later(VALID);
    }
  }
}

/*
 * mark all status lines of the current buffer for redraw
 */
void status_redraw_curbuf(void)
{
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    if (wp->w_status_height != 0 && wp->w_buffer == curbuf) {
      wp->w_redr_status = TRUE;
      redraw_later(VALID);
    }
  }
}

/*
 * Redraw all status lines that need to be redrawn.
 */
void redraw_statuslines(void)
{
  FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
    if (wp->w_redr_status) {
      win_redr_status(wp);
    }
  }
  if (redraw_tabline)
    draw_tabline();
}

/*
 * Redraw all status lines at the bottom of frame "frp".
 */
void win_redraw_last_status(frame_T *frp)
{
  if (frp->fr_layout == FR_LEAF)
    frp->fr_win->w_redr_status = TRUE;
  else if (frp->fr_layout == FR_ROW) {
    for (frp = frp->fr_child; frp != NULL; frp = frp->fr_next)
      win_redraw_last_status(frp);
  } else { /* frp->fr_layout == FR_COL */
    frp = frp->fr_child;
    while (frp->fr_next != NULL)
      frp = frp->fr_next;
    win_redraw_last_status(frp);
  }
}

/*
 * Draw the verticap separator right of window "wp" starting with line "row".
 */
static void draw_vsep_win(win_T *wp, int row)
{
  int hl;
  int c;

  if (wp->w_vsep_width) {
    /* draw the vertical separator right of this window */
    c = fillchar_vsep(&hl);
    screen_fill(wp->w_winrow + row, wp->w_winrow + wp->w_height,
        W_ENDCOL(wp), W_ENDCOL(wp) + 1,
        c, ' ', hl);
  }
}


/*
 * Get the length of an item as it will be shown in the status line.
 */
static int status_match_len(expand_T *xp, char_u *s)
{
  int len = 0;

  int emenu = (xp->xp_context == EXPAND_MENUS
               || xp->xp_context == EXPAND_MENUNAMES);

  /* Check for menu separators - replace with '|'. */
  if (emenu && menu_is_separator(s))
    return 1;

  while (*s != NUL) {
    s += skip_status_match_char(xp, s);
    len += ptr2cells(s);
    mb_ptr_adv(s);
  }

  return len;
}

/*
 * Return the number of characters that should be skipped in a status match.
 * These are backslashes used for escaping.  Do show backslashes in help tags.
 */
static int skip_status_match_char(expand_T *xp, char_u *s)
{
  if ((rem_backslash(s) && xp->xp_context != EXPAND_HELP)
      || ((xp->xp_context == EXPAND_MENUS
           || xp->xp_context == EXPAND_MENUNAMES)
          && (s[0] == '\t' || (s[0] == '\\' && s[1] != NUL)))
      ) {
#ifndef BACKSLASH_IN_FILENAME
    if (xp->xp_shell && csh_like_shell() && s[1] == '\\' && s[2] == '!')
      return 2;
#endif
    return 1;
  }
  return 0;
}

/*
 * Show wildchar matches in the status line.
 * Show at least the "match" item.
 * We start at item 'first_match' in the list and show all matches that fit.
 *
 * If inversion is possible we use it. Else '=' characters are used.
 */
void
win_redr_status_matches (
    expand_T *xp,
    int num_matches,
    char_u **matches,          /* list of matches */
    int match,
    int showtail
)
{
#define L_MATCH(m) (showtail ? sm_gettail(matches[m]) : matches[m])
  int row;
  char_u      *buf;
  int len;
  int clen;                     /* length in screen cells */
  int fillchar;
  int attr;
  int i;
  int highlight = TRUE;
  char_u      *selstart = NULL;
  int selstart_col = 0;
  char_u      *selend = NULL;
  static int first_match = 0;
  int add_left = FALSE;
  char_u      *s;
  int emenu;
  int l;

  if (matches == NULL)          /* interrupted completion? */
    return;

  buf = xmalloc(has_mbyte ? Columns * MB_MAXBYTES + 1 : Columns + 1);

  if (match == -1) {    /* don't show match but original text */
    match = 0;
    highlight = FALSE;
  }
  /* count 1 for the ending ">" */
  clen = status_match_len(xp, L_MATCH(match)) + 3;
  if (match == 0)
    first_match = 0;
  else if (match < first_match) {
    /* jumping left, as far as we can go */
    first_match = match;
    add_left = TRUE;
  } else {
    /* check if match fits on the screen */
    for (i = first_match; i < match; ++i)
      clen += status_match_len(xp, L_MATCH(i)) + 2;
    if (first_match > 0)
      clen += 2;
    /* jumping right, put match at the left */
    if ((long)clen > Columns) {
      first_match = match;
      /* if showing the last match, we can add some on the left */
      clen = 2;
      for (i = match; i < num_matches; ++i) {
        clen += status_match_len(xp, L_MATCH(i)) + 2;
        if ((long)clen >= Columns)
          break;
      }
      if (i == num_matches)
        add_left = TRUE;
    }
  }
  if (add_left)
    while (first_match > 0) {
      clen += status_match_len(xp, L_MATCH(first_match - 1)) + 2;
      if ((long)clen >= Columns)
        break;
      --first_match;
    }

  fillchar = fillchar_status(&attr, TRUE);

  if (first_match == 0) {
    *buf = NUL;
    len = 0;
  } else {
    STRCPY(buf, "< ");
    len = 2;
  }
  clen = len;

  i = first_match;
  while ((long)(clen + status_match_len(xp, L_MATCH(i)) + 2) < Columns) {
    if (i == match) {
      selstart = buf + len;
      selstart_col = clen;
    }

    s = L_MATCH(i);
    /* Check for menu separators - replace with '|' */
    emenu = (xp->xp_context == EXPAND_MENUS
             || xp->xp_context == EXPAND_MENUNAMES);
    if (emenu && menu_is_separator(s)) {
      STRCPY(buf + len, transchar('|'));
      l = (int)STRLEN(buf + len);
      len += l;
      clen += l;
    } else
      for (; *s != NUL; ++s) {
        s += skip_status_match_char(xp, s);
        clen += ptr2cells(s);
        if (has_mbyte && (l = (*mb_ptr2len)(s)) > 1) {
          STRNCPY(buf + len, s, l);
          s += l - 1;
          len += l;
        } else {
          STRCPY(buf + len, transchar_byte(*s));
          len += (int)STRLEN(buf + len);
        }
      }
    if (i == match)
      selend = buf + len;

    *(buf + len++) = ' ';
    *(buf + len++) = ' ';
    clen += 2;
    if (++i == num_matches)
      break;
  }

  if (i != num_matches) {
    *(buf + len++) = '>';
    ++clen;
  }

  buf[len] = NUL;

  row = cmdline_row - 1;
  if (row >= 0) {
    if (wild_menu_showing == 0) {
      if (msg_scrolled > 0) {
        /* Put the wildmenu just above the command line.  If there is
         * no room, scroll the screen one line up. */
        if (cmdline_row == Rows - 1) {
          screen_del_lines(0, 0, 1, (int)Rows, NULL);
          ++msg_scrolled;
        } else {
          ++cmdline_row;
          ++row;
        }
        wild_menu_showing = WM_SCROLLED;
      } else {
        /* Create status line if needed by setting 'laststatus' to 2.
         * Set 'winminheight' to zero to avoid that the window is
         * resized. */
        if (lastwin->w_status_height == 0) {
          save_p_ls = p_ls;
          save_p_wmh = p_wmh;
          p_ls = 2;
          p_wmh = 0;
          last_status(FALSE);
        }
        wild_menu_showing = WM_SHOWN;
      }
    }

    screen_puts(buf, row, 0, attr);
    if (selstart != NULL && highlight) {
      *selend = NUL;
      screen_puts(selstart, row, selstart_col, hl_attr(HLF_WM));
    }

    screen_fill(row, row + 1, clen, (int)Columns, fillchar, fillchar, attr);
  }

  win_redraw_last_status(topframe);
  xfree(buf);
}

/*
 * Redraw the status line of window wp.
 *
 * If inversion is possible we use it. Else '=' characters are used.
 */
void win_redr_status(win_T *wp)
{
  int row;
  char_u      *p;
  int len;
  int fillchar;
  int attr;
  int this_ru_col;
  static int busy = FALSE;

  /* It's possible to get here recursively when 'statusline' (indirectly)
   * invokes ":redrawstatus".  Simply ignore the call then. */
  if (busy)
    return;
  busy = TRUE;

  wp->w_redr_status = FALSE;
  if (wp->w_status_height == 0) {
    /* no status line, can only be last window */
    redraw_cmdline = TRUE;
  } else if (!redrawing()
             /* don't update status line when popup menu is visible and may be
              * drawn over it */
             || pum_visible()
             ) {
    /* Don't redraw right now, do it later. */
    wp->w_redr_status = TRUE;
  } else if (*p_stl != NUL || *wp->w_p_stl != NUL) {
    /* redraw custom status line */
    redraw_custom_statusline(wp);
  } else {
    fillchar = fillchar_status(&attr, wp == curwin);

    get_trans_bufname(wp->w_buffer);
    p = NameBuff;
    len = (int)STRLEN(p);

    if (wp->w_buffer->b_help
        || wp->w_p_pvw
        || bufIsChanged(wp->w_buffer)
        || wp->w_buffer->b_p_ro)
      *(p + len++) = ' ';
    if (wp->w_buffer->b_help) {
      STRCPY(p + len, _("[Help]"));
      len += (int)STRLEN(p + len);
    }
    if (wp->w_p_pvw) {
      STRCPY(p + len, _("[Preview]"));
      len += (int)STRLEN(p + len);
    }
    if (bufIsChanged(wp->w_buffer)) {
      STRCPY(p + len, "[+]");
      len += 3;
    }
    if (wp->w_buffer->b_p_ro) {
      STRCPY(p + len, _("[RO]"));
      len += 4;
    }

    this_ru_col = ru_col - (Columns - wp->w_width);
    if (this_ru_col < (wp->w_width + 1) / 2)
      this_ru_col = (wp->w_width + 1) / 2;
    if (this_ru_col <= 1) {
      p = (char_u *)"<";                /* No room for file name! */
      len = 1;
    } else if (has_mbyte) {
      int clen = 0, i;

      /* Count total number of display cells. */
      clen = (int) mb_string2cells(p);

      /* Find first character that will fit.
       * Going from start to end is much faster for DBCS. */
      for (i = 0; p[i] != NUL && clen >= this_ru_col - 1;
           i += (*mb_ptr2len)(p + i))
        clen -= (*mb_ptr2cells)(p + i);
      len = clen;
      if (i > 0) {
        p = p + i - 1;
        *p = '<';
        ++len;
      }

    } else if (len > this_ru_col - 1) {
      p += len - (this_ru_col - 1);
      *p = '<';
      len = this_ru_col - 1;
    }

    row = wp->w_winrow + wp->w_height;
    screen_puts(p, row, wp->w_wincol, attr);
    screen_fill(row, row + 1, len + wp->w_wincol,
        this_ru_col + wp->w_wincol, fillchar, fillchar, attr);

    if (get_keymap_str(wp, NameBuff, MAXPATHL)
        && this_ru_col - len > (int)(STRLEN(NameBuff) + 1))
      screen_puts(NameBuff, row, (int)(this_ru_col - STRLEN(NameBuff)
                                       - 1 + wp->w_wincol), attr);

    win_redr_ruler(wp, TRUE);
  }

  /*
   * May need to draw the character below the vertical separator.
   */
  if (wp->w_vsep_width != 0 && wp->w_status_height != 0 && redrawing()) {
    if (stl_connected(wp))
      fillchar = fillchar_status(&attr, wp == curwin);
    else
      fillchar = fillchar_vsep(&attr);
    screen_putchar(fillchar, wp->w_winrow + wp->w_height,
                   W_ENDCOL(wp), attr);
  }
  busy = FALSE;
}

/*
 * Redraw the status line according to 'statusline' and take care of any
 * errors encountered.
 */
static void redraw_custom_statusline(win_T *wp)
{
  static int entered = FALSE;
  int save_called_emsg = called_emsg;

  /* When called recursively return.  This can happen when the statusline
   * contains an expression that triggers a redraw. */
  if (entered)
    return;
  entered = TRUE;

  called_emsg = FALSE;
  win_redr_custom(wp, FALSE);
  if (called_emsg) {
    /* When there is an error disable the statusline, otherwise the
     * display is messed up with errors and a redraw triggers the problem
     * again and again. */
    set_string_option_direct((char_u *)"statusline", -1,
        (char_u *)"", OPT_FREE | (*wp->w_p_stl != NUL
                                  ? OPT_LOCAL : OPT_GLOBAL), SID_ERROR);
  }
  called_emsg |= save_called_emsg;
  entered = FALSE;
}

/*
 * Return TRUE if the status line of window "wp" is connected to the status
 * line of the window right of it.  If not, then it's a vertical separator.
 * Only call if (wp->w_vsep_width != 0).
 */
int stl_connected(win_T *wp)
{
  frame_T     *fr;

  fr = wp->w_frame;
  while (fr->fr_parent != NULL) {
    if (fr->fr_parent->fr_layout == FR_COL) {
      if (fr->fr_next != NULL)
        break;
    } else {
      if (fr->fr_next != NULL)
        return TRUE;
    }
    fr = fr->fr_parent;
  }
  return FALSE;
}


/*
 * Get the value to show for the language mappings, active 'keymap'.
 */
int
get_keymap_str (
    win_T *wp,
    char_u *buf,           /* buffer for the result */
    int len                    /* length of buffer */
)
{
  char_u      *p;

  if (wp->w_buffer->b_p_iminsert != B_IMODE_LMAP)
    return FALSE;

  {
    buf_T   *old_curbuf = curbuf;
    win_T   *old_curwin = curwin;
    char_u  *s;

    curbuf = wp->w_buffer;
    curwin = wp;
    STRCPY(buf, "b:keymap_name");       /* must be writable */
    ++emsg_skip;
    s = p = eval_to_string(buf, NULL, FALSE);
    --emsg_skip;
    curbuf = old_curbuf;
    curwin = old_curwin;
    if (p == NULL || *p == NUL) {
      if (wp->w_buffer->b_kmap_state & KEYMAP_LOADED)
        p = wp->w_buffer->b_p_keymap;
      else
        p = (char_u *)"lang";
    }
    if ((int)(STRLEN(p) + 3) < len)
      sprintf((char *)buf, "<%s>", p);
    else
      buf[0] = NUL;
    xfree(s);
  }
  return buf[0] != NUL;
}

/*
 * Redraw the status line or ruler of window "wp".
 * When "wp" is NULL redraw the tab pages line from 'tabline'.
 */
static void
win_redr_custom (
    win_T *wp,
    int draw_ruler                 /* TRUE or FALSE */
)
{
  static int entered = FALSE;
  int attr;
  int curattr;
  int row;
  int col = 0;
  int maxwidth;
  int width;
  int n;
  int len;
  int fillchar;
  char_u buf[MAXPATHL];
  char_u      *stl;
  char_u      *p;
  struct      stl_hlrec hltab[STL_MAX_ITEM];
  struct      stl_hlrec tabtab[STL_MAX_ITEM];
  int use_sandbox = FALSE;
  win_T       *ewp;
  int p_crb_save;

  /* There is a tiny chance that this gets called recursively: When
   * redrawing a status line triggers redrawing the ruler or tabline.
   * Avoid trouble by not allowing recursion. */
  if (entered)
    return;
  entered = TRUE;

  /* setup environment for the task at hand */
  if (wp == NULL) {
    /* Use 'tabline'.  Always at the first line of the screen. */
    stl = p_tal;
    row = 0;
    fillchar = ' ';
    attr = hl_attr(HLF_TPF);
    maxwidth = Columns;
    use_sandbox = was_set_insecurely((char_u *)"tabline", 0);
  } else {
    row = wp->w_winrow + wp->w_height;
    fillchar = fillchar_status(&attr, wp == curwin);
    maxwidth = wp->w_width;

    if (draw_ruler) {
      stl = p_ruf;
      /* advance past any leading group spec - implicit in ru_col */
      if (*stl == '%') {
        if (*++stl == '-')
          stl++;
        if (atoi((char *)stl))
          while (ascii_isdigit(*stl))
            stl++;
        if (*stl++ != '(')
          stl = p_ruf;
      }
      col = ru_col - (Columns - wp->w_width);
      if (col < (wp->w_width + 1) / 2)
        col = (wp->w_width + 1) / 2;
      maxwidth = wp->w_width - col;
      if (!wp->w_status_height) {
        row = Rows - 1;
        --maxwidth;             /* writing in last column may cause scrolling */
        fillchar = ' ';
        attr = 0;
      }

      use_sandbox = was_set_insecurely((char_u *)"rulerformat", 0);
    } else {
      if (*wp->w_p_stl != NUL)
        stl = wp->w_p_stl;
      else
        stl = p_stl;
      use_sandbox = was_set_insecurely((char_u *)"statusline",
          *wp->w_p_stl == NUL ? 0 : OPT_LOCAL);
    }

    col += wp->w_wincol;
  }

  if (maxwidth <= 0)
    goto theend;

  /* Temporarily reset 'cursorbind', we don't want a side effect from moving
   * the cursor away and back. */
  ewp = wp == NULL ? curwin : wp;
  p_crb_save = ewp->w_p_crb;
  ewp->w_p_crb = FALSE;

  /* Make a copy, because the statusline may include a function call that
   * might change the option value and free the memory. */
  stl = vim_strsave(stl);
  width = build_stl_str_hl(ewp, buf, sizeof(buf),
      stl, use_sandbox,
      fillchar, maxwidth, hltab, tabtab);
  xfree(stl);
  ewp->w_p_crb = p_crb_save;

  /* Make all characters printable. */
  p = transstr(buf);
  len = STRLCPY(buf, p, sizeof(buf));
  len = (size_t)len < sizeof(buf) ? len : (int)sizeof(buf) - 1;
  xfree(p);

  /* fill up with "fillchar" */
  while (width < maxwidth && len < (int)sizeof(buf) - 1) {
    len += (*mb_char2bytes)(fillchar, buf + len);
    ++width;
  }
  buf[len] = NUL;

  /*
   * Draw each snippet with the specified highlighting.
   */
  curattr = attr;
  p = buf;
  for (n = 0; hltab[n].start != NULL; n++) {
    int len = (int)(hltab[n].start - p);
    screen_puts_len(p, len, row, col, curattr);
    col += vim_strnsize(p, len);
    p = hltab[n].start;

    if (hltab[n].userhl == 0)
      curattr = attr;
    else if (hltab[n].userhl < 0)
      curattr = syn_id2attr(-hltab[n].userhl);
    else if (wp != NULL && wp != curwin && wp->w_status_height != 0)
      curattr = highlight_stlnc[hltab[n].userhl - 1];
    else
      curattr = highlight_user[hltab[n].userhl - 1];
  }
  // Make sure to use an empty string instead of p, if p is beyond buf + len.
  screen_puts(p >= buf + len ? (char_u *)"" : p, row, col, curattr);

  if (wp == NULL) {
    /* Fill the TabPageIdxs[] array for clicking in the tab pagesline. */
    col = 0;
    len = 0;
    p = buf;
    fillchar = 0;
    for (n = 0; tabtab[n].start != NULL; n++) {
      len += vim_strnsize(p, (int)(tabtab[n].start - p));
      while (col < len)
        TabPageIdxs[col++] = fillchar;
      p = tabtab[n].start;
      fillchar = tabtab[n].userhl;
    }
    while (col < Columns)
      TabPageIdxs[col++] = fillchar;
  }

theend:
  entered = FALSE;
}


/*
 * Output a single character directly to the screen and update ScreenLines.
 */
void screen_putchar(int c, int row, int col, int attr)
{
  char_u buf[MB_MAXBYTES + 1];

  if (has_mbyte)
    buf[(*mb_char2bytes)(c, buf)] = NUL;
  else {
    buf[0] = c;
    buf[1] = NUL;
  }
  screen_puts(buf, row, col, attr);
}

/*
 * Get a single character directly from ScreenLines into "bytes[]".
 * Also return its attribute in *attrp;
 */
void screen_getbytes(int row, int col, char_u *bytes, int *attrp)
{
  unsigned off;

  /* safety check */
  if (ScreenLines != NULL && row < screen_Rows && col < screen_Columns) {
    off = LineOffset[row] + col;
    *attrp = ScreenAttrs[off];
    bytes[0] = ScreenLines[off];
    bytes[1] = NUL;

    if (enc_utf8 && ScreenLinesUC[off] != 0)
      bytes[utfc_char2bytes(off, bytes)] = NUL;
    else if (enc_dbcs == DBCS_JPNU && ScreenLines[off] == 0x8e) {
      bytes[0] = ScreenLines[off];
      bytes[1] = ScreenLines2[off];
      bytes[2] = NUL;
    } else if (enc_dbcs && MB_BYTE2LEN(bytes[0]) > 1) {
      bytes[1] = ScreenLines[off + 1];
      bytes[2] = NUL;
    }
  }
}


/*
 * Return TRUE if composing characters for screen posn "off" differs from
 * composing characters in "u8cc".
 * Only to be used when ScreenLinesUC[off] != 0.
 */
static int screen_comp_differs(int off, int *u8cc)
{
  int i;

  for (i = 0; i < Screen_mco; ++i) {
    if (ScreenLinesC[i][off] != (u8char_T)u8cc[i])
      return TRUE;
    if (u8cc[i] == 0)
      break;
  }
  return FALSE;
}

/*
 * Put string '*text' on the screen at position 'row' and 'col', with
 * attributes 'attr', and update ScreenLines[] and ScreenAttrs[].
 * Note: only outputs within one row, message is truncated at screen boundary!
 * Note: if ScreenLines[], row and/or col is invalid, nothing is done.
 */
void screen_puts(char_u *text, int row, int col, int attr)
{
  screen_puts_len(text, -1, row, col, attr);
}

/*
 * Like screen_puts(), but output "text[len]".  When "len" is -1 output up to
 * a NUL.
 */
void screen_puts_len(char_u *text, int textlen, int row, int col, int attr)
{
  unsigned off;
  char_u      *ptr = text;
  int len = textlen;
  int c;
  unsigned max_off;
  int mbyte_blen = 1;
  int mbyte_cells = 1;
  int u8c = 0;
  int u8cc[MAX_MCO];
  int clear_next_cell = FALSE;
  int prev_c = 0;                       /* previous Arabic character */
  int pc, nc, nc1;
  int pcc[MAX_MCO];
  int force_redraw_this;
  int force_redraw_next = FALSE;
  int need_redraw;

  const int l_has_mbyte = has_mbyte;
  const bool l_enc_utf8 = enc_utf8;
  const int l_enc_dbcs = enc_dbcs;

  assert((l_has_mbyte == (l_enc_utf8 || l_enc_dbcs))
         && !(l_enc_utf8 && l_enc_dbcs));

  if (ScreenLines == NULL || row >= screen_Rows)        /* safety check */
    return;
  off = LineOffset[row] + col;

  /* When drawing over the right halve of a double-wide char clear out the
   * left halve.  Only needed in a terminal. */
  if (l_has_mbyte && col > 0 && col < screen_Columns
      && mb_fix_col(col, row) != col) {
    ScreenLines[off - 1] = ' ';
    ScreenAttrs[off - 1] = 0;
    if (l_enc_utf8) {
      ScreenLinesUC[off - 1] = 0;
      ScreenLinesC[0][off - 1] = 0;
    }
    /* redraw the previous cell, make it empty */
    screen_char(off - 1, row, col - 1);
    /* force the cell at "col" to be redrawn */
    force_redraw_next = TRUE;
  }

  max_off = LineOffset[row] + screen_Columns;
  while (col < screen_Columns
         && (len < 0 || (int)(ptr - text) < len)
         && *ptr != NUL) {
    c = *ptr;
    /* check if this is the first byte of a multibyte */
    if (l_has_mbyte) {
      if (l_enc_utf8 && len > 0)
        mbyte_blen = utfc_ptr2len_len(ptr, (int)((text + len) - ptr));
      else
        mbyte_blen = (*mb_ptr2len)(ptr);
      if (l_enc_dbcs == DBCS_JPNU && c == 0x8e)
        mbyte_cells = 1;
      else if (l_enc_dbcs != 0)
        mbyte_cells = mbyte_blen;
      else {            /* enc_utf8 */
        if (len >= 0)
          u8c = utfc_ptr2char_len(ptr, u8cc,
              (int)((text + len) - ptr));
        else
          u8c = utfc_ptr2char(ptr, u8cc);
        mbyte_cells = utf_char2cells(u8c);
        if (p_arshape && !p_tbidi && arabic_char(u8c)) {
          /* Do Arabic shaping. */
          if (len >= 0 && (int)(ptr - text) + mbyte_blen >= len) {
            /* Past end of string to be displayed. */
            nc = NUL;
            nc1 = NUL;
          } else {
            nc = utfc_ptr2char_len(ptr + mbyte_blen, pcc,
                (int)((text + len) - ptr - mbyte_blen));
            nc1 = pcc[0];
          }
          pc = prev_c;
          prev_c = u8c;
          u8c = arabic_shape(u8c, &c, &u8cc[0], nc, nc1, pc);
        } else
          prev_c = u8c;
        if (col + mbyte_cells > screen_Columns) {
          /* Only 1 cell left, but character requires 2 cells:
           * display a '>' in the last column to avoid wrapping. */
          c = '>';
          mbyte_cells = 1;
        }
      }
    }

    force_redraw_this = force_redraw_next;
    force_redraw_next = FALSE;

    need_redraw = ScreenLines[off] != c
                  || (mbyte_cells == 2
                      && ScreenLines[off + 1] != (l_enc_dbcs ? ptr[1] : 0))
                  || (l_enc_dbcs == DBCS_JPNU
                      && c == 0x8e
                      && ScreenLines2[off] != ptr[1])
                  || (l_enc_utf8
                      && (ScreenLinesUC[off] !=
                          (u8char_T)(c < 0x80 && u8cc[0] == 0 ? 0 : u8c)
                          || (ScreenLinesUC[off] != 0
                              && screen_comp_differs(off, u8cc))))
                  || ScreenAttrs[off] != attr
                  || exmode_active;

    if (need_redraw
        || force_redraw_this
        ) {
      /* When at the end of the text and overwriting a two-cell
       * character with a one-cell character, need to clear the next
       * cell.  Also when overwriting the left halve of a two-cell char
       * with the right halve of a two-cell char.  Do this only once
       * (mb_off2cells() may return 2 on the right halve). */
      if (clear_next_cell)
        clear_next_cell = FALSE;
      else if (l_has_mbyte
               && (len < 0 ? ptr[mbyte_blen] == NUL
                   : ptr + mbyte_blen >= text + len)
               && ((mbyte_cells == 1 && (*mb_off2cells)(off, max_off) > 1)
                   || (mbyte_cells == 2
                       && (*mb_off2cells)(off, max_off) == 1
                       && (*mb_off2cells)(off + 1, max_off) > 1)))
        clear_next_cell = TRUE;

      /* Make sure we never leave a second byte of a double-byte behind,
       * it confuses mb_off2cells(). */
      if (l_enc_dbcs
          && ((mbyte_cells == 1 && (*mb_off2cells)(off, max_off) > 1)
              || (mbyte_cells == 2
                  && (*mb_off2cells)(off, max_off) == 1
                  && (*mb_off2cells)(off + 1, max_off) > 1)))
        ScreenLines[off + mbyte_blen] = 0;
      ScreenLines[off] = c;
      ScreenAttrs[off] = attr;
      if (l_enc_utf8) {
        if (c < 0x80 && u8cc[0] == 0)
          ScreenLinesUC[off] = 0;
        else {
          int i;

          ScreenLinesUC[off] = u8c;
          for (i = 0; i < Screen_mco; ++i) {
            ScreenLinesC[i][off] = u8cc[i];
            if (u8cc[i] == 0)
              break;
          }
        }
        if (mbyte_cells == 2) {
          ScreenLines[off + 1] = 0;
          ScreenAttrs[off + 1] = attr;
        }
        screen_char(off, row, col);
      } else if (mbyte_cells == 2) {
        ScreenLines[off + 1] = ptr[1];
        ScreenAttrs[off + 1] = attr;
        screen_char_2(off, row, col);
      } else if (l_enc_dbcs == DBCS_JPNU && c == 0x8e) {
        ScreenLines2[off] = ptr[1];
        screen_char(off, row, col);
      } else
        screen_char(off, row, col);
    }
    if (l_has_mbyte) {
      off += mbyte_cells;
      col += mbyte_cells;
      ptr += mbyte_blen;
      if (clear_next_cell) {
        // This only happens at the end, display one space next.
        ptr = (char_u *)" ";
        len = -1;
      }
    } else {
      ++off;
      ++col;
      ++ptr;
    }
  }

  /* If we detected the next character needs to be redrawn, but the text
   * doesn't extend up to there, update the character here. */
  if (force_redraw_next && col < screen_Columns) {
    if (l_enc_dbcs != 0 && dbcs_off2cells(off, max_off) > 1)
      screen_char_2(off, row, col);
    else
      screen_char(off, row, col);
  }
}

/*
 * Prepare for 'hlsearch' highlighting.
 */
static void start_search_hl(void)
{
  if (p_hls && !no_hlsearch) {
    last_pat_prog(&search_hl.rm);
    search_hl.attr = hl_attr(HLF_L);
    /* Set the time limit to 'redrawtime'. */
    search_hl.tm = profile_setlimit(p_rdt);
  }
}

/*
 * Clean up for 'hlsearch' highlighting.
 */
static void end_search_hl(void)
{
  if (search_hl.rm.regprog != NULL) {
    vim_regfree(search_hl.rm.regprog);
    search_hl.rm.regprog = NULL;
  }
}

/*
 * Init for calling prepare_search_hl().
 */
static void init_search_hl(win_T *wp)
{
  matchitem_T *cur;

  /* Setup for match and 'hlsearch' highlighting.  Disable any previous
   * match */
  cur = wp->w_match_head;
  while (cur != NULL) {
    cur->hl.rm = cur->match;
    if (cur->hlg_id == 0)
      cur->hl.attr = 0;
    else
      cur->hl.attr = syn_id2attr(cur->hlg_id);
    cur->hl.buf = wp->w_buffer;
    cur->hl.lnum = 0;
    cur->hl.first_lnum = 0;
    /* Set the time limit to 'redrawtime'. */
    cur->hl.tm = profile_setlimit(p_rdt);
    cur = cur->next;
  }
  search_hl.buf = wp->w_buffer;
  search_hl.lnum = 0;
  search_hl.first_lnum = 0;
  /* time limit is set at the toplevel, for all windows */
}

/*
 * Advance to the match in window "wp" line "lnum" or past it.
 */
static void prepare_search_hl(win_T *wp, linenr_T lnum)
{
  matchitem_T *cur;             /* points to the match list */
  match_T     *shl;             /* points to search_hl or a match */
  int shl_flag;                 /* flag to indicate whether search_hl
                                   has been processed or not */
  int n;

  /*
   * When using a multi-line pattern, start searching at the top
   * of the window or just after a closed fold.
   * Do this both for search_hl and the match list.
   */
  cur = wp->w_match_head;
  shl_flag = FALSE;
  while (cur != NULL || shl_flag == FALSE) {
    if (shl_flag == FALSE) {
      shl = &search_hl;
      shl_flag = TRUE;
    } else
      shl = &cur->hl;
    if (shl->rm.regprog != NULL
        && shl->lnum == 0
        && re_multiline(shl->rm.regprog)) {
      if (shl->first_lnum == 0) {
        for (shl->first_lnum = lnum;
             shl->first_lnum > wp->w_topline; --shl->first_lnum)
          if (hasFoldingWin(wp, shl->first_lnum - 1,
                  NULL, NULL, TRUE, NULL))
            break;
      }
      if (cur != NULL) {
        cur->pos.cur = 0;
      }
      bool pos_inprogress = true; // mark that a position match search is
                                  // in progress
      n = 0;
      while (shl->first_lnum < lnum && (shl->rm.regprog != NULL
                                    || (cur != NULL && pos_inprogress))) {
        next_search_hl(wp, shl, shl->first_lnum, (colnr_T)n, cur);
        pos_inprogress = !(cur == NULL ||  cur->pos.cur == 0);
        if (shl->lnum != 0) {
          shl->first_lnum = shl->lnum
                            + shl->rm.endpos[0].lnum
                            - shl->rm.startpos[0].lnum;
          n = shl->rm.endpos[0].col;
        } else {
          ++shl->first_lnum;
          n = 0;
        }
      }
    }
    if (shl != &search_hl && cur != NULL)
      cur = cur->next;
  }
}

/*
 * Search for a next 'hlsearch' or match.
 * Uses shl->buf.
 * Sets shl->lnum and shl->rm contents.
 * Note: Assumes a previous match is always before "lnum", unless
 * shl->lnum is zero.
 * Careful: Any pointers for buffer lines will become invalid.
 */
static void
next_search_hl (
    win_T *win,
    match_T *shl,               /* points to search_hl or a match */
    linenr_T lnum,
    colnr_T mincol,                /* minimal column for a match */
    matchitem_T *cur               /* to retrieve match positions if any */
)
{
  linenr_T l;
  colnr_T matchcol;
  long nmatched = 0;

  if (shl->lnum != 0) {
    /* Check for three situations:
     * 1. If the "lnum" is below a previous match, start a new search.
     * 2. If the previous match includes "mincol", use it.
     * 3. Continue after the previous match.
     */
    l = shl->lnum + shl->rm.endpos[0].lnum - shl->rm.startpos[0].lnum;
    if (lnum > l)
      shl->lnum = 0;
    else if (lnum < l || shl->rm.endpos[0].col > mincol)
      return;
  }

  /*
   * Repeat searching for a match until one is found that includes "mincol"
   * or none is found in this line.
   */
  called_emsg = FALSE;
  for (;; ) {
    /* Stop searching after passing the time limit. */
    if (profile_passed_limit(shl->tm)) {
      shl->lnum = 0;                    /* no match found in time */
      break;
    }
    /* Three situations:
     * 1. No useful previous match: search from start of line.
     * 2. Not Vi compatible or empty match: continue at next character.
     *    Break the loop if this is beyond the end of the line.
     * 3. Vi compatible searching: continue at end of previous match.
     */
    if (shl->lnum == 0)
      matchcol = 0;
    else if (vim_strchr(p_cpo, CPO_SEARCH) == NULL
        || (shl->rm.endpos[0].lnum == 0
          && shl->rm.endpos[0].col <= shl->rm.startpos[0].col)) {
      char_u      *ml;

      matchcol = shl->rm.startpos[0].col;
      ml = ml_get_buf(shl->buf, lnum, FALSE) + matchcol;
      if (*ml == NUL) {
        ++matchcol;
        shl->lnum = 0;
        break;
      }
      if (has_mbyte)
        matchcol += mb_ptr2len(ml);
      else
        ++matchcol;
    } else
      matchcol = shl->rm.endpos[0].col;

    shl->lnum = lnum;
    if (shl->rm.regprog != NULL) {
      /* Remember whether shl->rm is using a copy of the regprog in
       * cur->match. */
      bool regprog_is_copy = (shl != &search_hl
                              && cur != NULL
                              && shl == &cur->hl
                              && cur->match.regprog == cur->hl.rm.regprog);

      nmatched = vim_regexec_multi(&shl->rm, win, shl->buf, lnum, matchcol, &(shl->tm));
      /* Copy the regprog, in case it got freed and recompiled. */
      if (regprog_is_copy) {
        cur->match.regprog = cur->hl.rm.regprog;
      }
      if (called_emsg || got_int) {
        // Error while handling regexp: stop using this regexp.
        if (shl == &search_hl) {
          // don't free regprog in the match list, it's a copy
          vim_regfree(shl->rm.regprog);
          SET_NO_HLSEARCH(TRUE);
        }
        shl->rm.regprog = NULL;
        shl->lnum = 0;
        got_int = FALSE; // avoid the "Type :quit to exit Vim" message
        break;
      }
    } else if (cur != NULL) {
      nmatched = next_search_hl_pos(shl, lnum, &(cur->pos), matchcol);
    }
    if (nmatched == 0) {
      shl->lnum = 0;                    /* no match found */
      break;
    }
    if (shl->rm.startpos[0].lnum > 0
        || shl->rm.startpos[0].col >= mincol
        || nmatched > 1
        || shl->rm.endpos[0].col > mincol) {
      shl->lnum += shl->rm.startpos[0].lnum;
      break;                            /* useful match found */
    }
  }
}

static int
next_search_hl_pos(
    match_T *shl,         // points to a match
    linenr_T lnum,
    posmatch_T *posmatch, // match positions
    colnr_T mincol        // minimal column for a match
)
{
  int i;
  int bot = -1;

  shl->lnum = 0;
  for (i = posmatch->cur; i < MAXPOSMATCH; i++) {
    if (posmatch->pos[i].lnum == 0) {
      break;
    }
    if (posmatch->pos[i].col < mincol) {
      continue;
    }
    if (posmatch->pos[i].lnum == lnum) {
      if (bot != -1) {
        // partially sort positions by column numbers
        // on the same line
        if (posmatch->pos[i].col < posmatch->pos[bot].col) {
          llpos_T tmp = posmatch->pos[i];

          posmatch->pos[i] = posmatch->pos[bot];
          posmatch->pos[bot] = tmp;
        }
      } else {
        bot = i;
        shl->lnum = lnum;
      }
    }
  }
  posmatch->cur = 0;
  if (bot != -1) {
    colnr_T start = posmatch->pos[bot].col == 0
                    ? 0: posmatch->pos[bot].col - 1;
    colnr_T end = posmatch->pos[bot].col == 0
                  ? MAXCOL : start + posmatch->pos[bot].len;

    shl->rm.startpos[0].lnum = 0;
    shl->rm.startpos[0].col = start;
    shl->rm.endpos[0].lnum = 0;
    shl->rm.endpos[0].col = end;
    posmatch->cur = bot + 1;
    return true;
  }
  return false;
}

static void screen_start_highlight(int attr)
{
  screen_attr = attr;
  ui_start_highlight(attr);
}

void screen_stop_highlight(void)
{
  ui_stop_highlight();
  screen_attr = 0;
}

/*
 * Put character ScreenLines["off"] on the screen at position "row" and "col",
 * using the attributes from ScreenAttrs["off"].
 */
static void screen_char(unsigned off, int row, int col)
{
  int attr;

  /* Check for illegal values, just in case (could happen just after
   * resizing). */
  if (row >= screen_Rows || col >= screen_Columns)
    return;

  /* Outputting the last character on the screen may scrollup the screen.
   * Don't to it!  Mark the character invalid (update it when scrolled up) */
  if (row == screen_Rows - 1 && col == screen_Columns - 1
      /* account for first command-line character in rightleft mode */
      && !cmdmsg_rl
      ) {
    ScreenAttrs[off] = (sattr_T)-1;
    return;
  }

  /*
   * Stop highlighting first, so it's easier to move the cursor.
   */
  if (screen_char_attr != 0)
    attr = screen_char_attr;
  else
    attr = ScreenAttrs[off];
  if (screen_attr != attr)
    screen_stop_highlight();

  ui_cursor_goto(row, col);

  if (screen_attr != attr)
    screen_start_highlight(attr);

  if (enc_utf8 && ScreenLinesUC[off] != 0) {
    char_u buf[MB_MAXBYTES + 1];

    // Convert UTF-8 character to bytes and write it.
    buf[utfc_char2bytes(off, buf)] = NUL;
    ui_puts(buf);
  } else {
    ui_putc(ScreenLines[off]);
    // double-byte character in single-width cell
    if (enc_dbcs == DBCS_JPNU && ScreenLines[off] == 0x8e) {
      ui_putc(ScreenLines2[off]);
    }
  }
}

/*
 * Used for enc_dbcs only: Put one double-wide character at ScreenLines["off"]
 * on the screen at position 'row' and 'col'.
 * The attributes of the first byte is used for all.  This is required to
 * output the two bytes of a double-byte character with nothing in between.
 */
static void screen_char_2(unsigned off, int row, int col)
{
  /* Check for illegal values (could be wrong when screen was resized). */
  if (off + 1 >= (unsigned)(screen_Rows * screen_Columns))
    return;

  /* Outputting the last character on the screen may scrollup the screen.
   * Don't to it!  Mark the character invalid (update it when scrolled up) */
  if (row == screen_Rows - 1 && col >= screen_Columns - 2) {
    ScreenAttrs[off] = (sattr_T)-1;
    return;
  }

  /* Output the first byte normally (positions the cursor), then write the
   * second byte directly. */
  screen_char(off, row, col);
  ui_putc(ScreenLines[off + 1]);
}

/*
 * Fill the screen from 'start_row' to 'end_row', from 'start_col' to 'end_col'
 * with character 'c1' in first column followed by 'c2' in the other columns.
 * Use attributes 'attr'.
 */
void screen_fill(int start_row, int end_row, int start_col, int end_col, int c1, int c2, int attr)
{
  int row;
  int col;
  int off;
  int end_off;
  int did_delete;
  int c;

  if (end_row > screen_Rows)            /* safety check */
    end_row = screen_Rows;
  if (end_col > screen_Columns)         /* safety check */
    end_col = screen_Columns;
  if (ScreenLines == NULL
      || start_row >= end_row
      || start_col >= end_col)          /* nothing to do */
    return;

  /* it's a "normal" terminal when not in a GUI or cterm */
  for (row = start_row; row < end_row; ++row) {
    if (has_mbyte) {
      // When drawing over the right halve of a double-wide char clear
      // out the left halve.  When drawing over the left halve of a
      // double wide-char clear out the right halve.  Only needed in a
      // terminal.
      if (start_col > 0 && mb_fix_col(start_col, row) != start_col) {
        screen_puts_len((char_u *)" ", 1, row, start_col - 1, 0);
      }
      if (end_col < screen_Columns && mb_fix_col(end_col, row) != end_col) {
        screen_puts_len((char_u *)" ", 1, row, end_col, 0);
      }
    }
    /*
     * Try to use delete-line termcap code, when no attributes or in a
     * "normal" terminal, where a bold/italic space is just a
     * space.
     */
    did_delete = FALSE;
    if (c2 == ' '
        && end_col == Columns
        && attr == 0) {
      /*
       * check if we really need to clear something
       */
      col = start_col;
      if (c1 != ' ')                            /* don't clear first char */
        ++col;

      off = LineOffset[row] + col;
      end_off = LineOffset[row] + end_col;

      /* skip blanks (used often, keep it fast!) */
      if (enc_utf8)
        while (off < end_off && ScreenLines[off] == ' '
               && ScreenAttrs[off] == 0 && ScreenLinesUC[off] == 0)
          ++off;
      else
        while (off < end_off && ScreenLines[off] == ' '
               && ScreenAttrs[off] == 0)
          ++off;
      if (off < end_off) {              /* something to be cleared */
        col = off - LineOffset[row];
        screen_stop_highlight();
        ui_cursor_goto(row, col);        // clear rest of this screen line
        ui_eol_clear();
        col = end_col - col;
        while (col--) {                 /* clear chars in ScreenLines */
          ScreenLines[off] = ' ';
          if (enc_utf8)
            ScreenLinesUC[off] = 0;
          ScreenAttrs[off] = 0;
          ++off;
        }
      }
      did_delete = TRUE;                /* the chars are cleared now */
    }

    off = LineOffset[row] + start_col;
    c = c1;
    for (col = start_col; col < end_col; ++col) {
      if (ScreenLines[off] != c
          || (enc_utf8 && (int)ScreenLinesUC[off]
              != (c >= 0x80 ? c : 0))
          || ScreenAttrs[off] != attr
          ) {
        ScreenLines[off] = c;
        if (enc_utf8) {
          if (c >= 0x80) {
            ScreenLinesUC[off] = c;
            ScreenLinesC[0][off] = 0;
          } else
            ScreenLinesUC[off] = 0;
        }
        ScreenAttrs[off] = attr;
        if (!did_delete || c != ' ')
          screen_char(off, row, col);
      }
      ++off;
      if (col == start_col) {
        if (did_delete)
          break;
        c = c2;
      }
    }
    if (end_col == Columns)
      LineWraps[row] = FALSE;
    if (row == Rows - 1) {              /* overwritten the command line */
      redraw_cmdline = TRUE;
      if (c1 == ' ' && c2 == ' ')
        clear_cmdline = FALSE;          /* command line has been cleared */
      if (start_col == 0)
        mode_displayed = FALSE;         /* mode cleared or overwritten */
    }
  }
}

/*
 * Check if there should be a delay.  Used before clearing or redrawing the
 * screen or the command line.
 */
void check_for_delay(int check_msg_scroll)
{
  if ((emsg_on_display || (check_msg_scroll && msg_scroll))
      && !did_wait_return
      && emsg_silent == 0) {
    ui_flush();
    os_delay(1000L, true);
    emsg_on_display = FALSE;
    if (check_msg_scroll)
      msg_scroll = FALSE;
  }
}

/*
 * screen_valid -  allocate screen buffers if size changed
 *   If "doclear" is TRUE: clear screen if it has been resized.
 *	Returns TRUE if there is a valid screen to write to.
 *	Returns FALSE when starting up and screen not initialized yet.
 */
int screen_valid(int doclear)
{
  screenalloc(doclear);            /* allocate screen buffers if size changed */
  return ScreenLines != NULL;
}

/*
 * Resize the shell to Rows and Columns.
 * Allocate ScreenLines[] and associated items.
 *
 * There may be some time between setting Rows and Columns and (re)allocating
 * ScreenLines[].  This happens when starting up and when (manually) changing
 * the shell size.  Always use screen_Rows and screen_Columns to access items
 * in ScreenLines[].  Use Rows and Columns for positioning text etc. where the
 * final size of the shell is needed.
 */
void screenalloc(bool doclear)
{
  int new_row, old_row;
  int outofmem = FALSE;
  int len;
  schar_T         *new_ScreenLines;
  u8char_T        *new_ScreenLinesUC = NULL;
  u8char_T        *new_ScreenLinesC[MAX_MCO];
  schar_T         *new_ScreenLines2 = NULL;
  int i;
  sattr_T         *new_ScreenAttrs;
  unsigned        *new_LineOffset;
  char_u          *new_LineWraps;
  short           *new_TabPageIdxs;
  static int entered = FALSE;                   /* avoid recursiveness */
  static int done_outofmem_msg = FALSE;         /* did outofmem message */
  int retry_count = 0;
  const bool l_enc_utf8 = enc_utf8;
  const int l_enc_dbcs = enc_dbcs;

retry:
  /*
   * Allocation of the screen buffers is done only when the size changes and
   * when Rows and Columns have been set and we have started doing full
   * screen stuff.
   */
  if ((ScreenLines != NULL
       && Rows == screen_Rows
       && Columns == screen_Columns
       && l_enc_utf8 == (ScreenLinesUC != NULL)
       && (l_enc_dbcs == DBCS_JPNU) == (ScreenLines2 != NULL)
       && p_mco == Screen_mco
       )
      || Rows == 0
      || Columns == 0
      || (!full_screen && ScreenLines == NULL))
    return;

  /*
   * It's possible that we produce an out-of-memory message below, which
   * will cause this function to be called again.  To break the loop, just
   * return here.
   */
  if (entered)
    return;
  entered = TRUE;

  /*
   * Note that the window sizes are updated before reallocating the arrays,
   * thus we must not redraw here!
   */
  ++RedrawingDisabled;

  win_new_shellsize();      /* fit the windows in the new sized shell */

  comp_col();           /* recompute columns for shown command and ruler */

  /*
   * We're changing the size of the screen.
   * - Allocate new arrays for ScreenLines and ScreenAttrs.
   * - Move lines from the old arrays into the new arrays, clear extra
   *	 lines (unless the screen is going to be cleared).
   * - Free the old arrays.
   *
   * If anything fails, make ScreenLines NULL, so we don't do anything!
   * Continuing with the old ScreenLines may result in a crash, because the
   * size is wrong.
   */
  FOR_ALL_TAB_WINDOWS(tp, wp) {
    win_free_lsize(wp);
  }
  if (aucmd_win != NULL)
    win_free_lsize(aucmd_win);

  new_ScreenLines = xmalloc((size_t)((Rows + 1) * Columns * sizeof(schar_T)));
  memset(new_ScreenLinesC, 0, sizeof(u8char_T *) * MAX_MCO);
  if (l_enc_utf8) {
    new_ScreenLinesUC = xmalloc(
        (size_t)((Rows + 1) * Columns * sizeof(u8char_T)));
    for (i = 0; i < p_mco; ++i)
      new_ScreenLinesC[i] = xcalloc((Rows + 1) * Columns, sizeof(u8char_T));
  }
  if (l_enc_dbcs == DBCS_JPNU)
    new_ScreenLines2 = xmalloc(
        (size_t)((Rows + 1) * Columns * sizeof(schar_T)));
  new_ScreenAttrs = xmalloc((size_t)((Rows + 1) * Columns * sizeof(sattr_T)));
  new_LineOffset = xmalloc((size_t)(Rows * sizeof(unsigned)));
  new_LineWraps = xmalloc((size_t)(Rows * sizeof(char_u)));
  new_TabPageIdxs = xmalloc((size_t)(Columns * sizeof(short)));

  FOR_ALL_TAB_WINDOWS(tp, wp) {
    win_alloc_lines(wp);
  }
  if (aucmd_win != NULL && aucmd_win->w_lines == NULL) {
    win_alloc_lines(aucmd_win);
  }

  for (i = 0; i < p_mco; ++i)
    if (new_ScreenLinesC[i] == NULL)
      break;
  if (new_ScreenLines == NULL
      || (l_enc_utf8 && (new_ScreenLinesUC == NULL || i != p_mco))
      || (l_enc_dbcs == DBCS_JPNU && new_ScreenLines2 == NULL)
      || new_ScreenAttrs == NULL
      || new_LineOffset == NULL
      || new_LineWraps == NULL
      || new_TabPageIdxs == NULL
      || outofmem) {
    if (ScreenLines != NULL || !done_outofmem_msg) {
      /* guess the size */
      do_outofmem_msg((Rows + 1) * Columns);

      /* Remember we did this to avoid getting outofmem messages over
       * and over again. */
      done_outofmem_msg = TRUE;
    }
    xfree(new_ScreenLines);
    new_ScreenLines = NULL;
    xfree(new_ScreenLinesUC);
    new_ScreenLinesUC = NULL;
    for (i = 0; i < p_mco; ++i) {
      xfree(new_ScreenLinesC[i]);
      new_ScreenLinesC[i] = NULL;
    }
    xfree(new_ScreenLines2);
    new_ScreenLines2 = NULL;
    xfree(new_ScreenAttrs);
    new_ScreenAttrs = NULL;
    xfree(new_LineOffset);
    new_LineOffset = NULL;
    xfree(new_LineWraps);
    new_LineWraps = NULL;
    xfree(new_TabPageIdxs);
    new_TabPageIdxs = NULL;
  } else {
    done_outofmem_msg = FALSE;

    for (new_row = 0; new_row < Rows; ++new_row) {
      new_LineOffset[new_row] = new_row * Columns;
      new_LineWraps[new_row] = FALSE;

      /*
       * If the screen is not going to be cleared, copy as much as
       * possible from the old screen to the new one and clear the rest
       * (used when resizing the window at the "--more--" prompt or when
       * executing an external command, for the GUI).
       */
      if (!doclear) {
        (void)memset(new_ScreenLines + new_row * Columns,
            ' ', (size_t)Columns * sizeof(schar_T));
        if (l_enc_utf8) {
          (void)memset(new_ScreenLinesUC + new_row * Columns,
              0, (size_t)Columns * sizeof(u8char_T));
          for (i = 0; i < p_mco; ++i)
            (void)memset(new_ScreenLinesC[i]
                + new_row * Columns,
                0, (size_t)Columns * sizeof(u8char_T));
        }
        if (l_enc_dbcs == DBCS_JPNU)
          (void)memset(new_ScreenLines2 + new_row * Columns,
              0, (size_t)Columns * sizeof(schar_T));
        (void)memset(new_ScreenAttrs + new_row * Columns,
            0, (size_t)Columns * sizeof(sattr_T));
        old_row = new_row + (screen_Rows - Rows);
        if (old_row >= 0 && ScreenLines != NULL) {
          if (screen_Columns < Columns)
            len = screen_Columns;
          else
            len = Columns;
          /* When switching to utf-8 don't copy characters, they
           * may be invalid now.  Also when p_mco changes. */
          if (!(l_enc_utf8 && ScreenLinesUC == NULL)
              && p_mco == Screen_mco)
            memmove(new_ScreenLines + new_LineOffset[new_row],
                ScreenLines + LineOffset[old_row],
                (size_t)len * sizeof(schar_T));
          if (l_enc_utf8 && ScreenLinesUC != NULL
              && p_mco == Screen_mco) {
            memmove(new_ScreenLinesUC + new_LineOffset[new_row],
                ScreenLinesUC + LineOffset[old_row],
                (size_t)len * sizeof(u8char_T));
            for (i = 0; i < p_mco; ++i)
              memmove(new_ScreenLinesC[i]
                  + new_LineOffset[new_row],
                  ScreenLinesC[i] + LineOffset[old_row],
                  (size_t)len * sizeof(u8char_T));
          }
          if (l_enc_dbcs == DBCS_JPNU && ScreenLines2 != NULL)
            memmove(new_ScreenLines2 + new_LineOffset[new_row],
                ScreenLines2 + LineOffset[old_row],
                (size_t)len * sizeof(schar_T));
          memmove(new_ScreenAttrs + new_LineOffset[new_row],
              ScreenAttrs + LineOffset[old_row],
              (size_t)len * sizeof(sattr_T));
        }
      }
    }
    /* Use the last line of the screen for the current line. */
    current_ScreenLine = new_ScreenLines + Rows * Columns;
  }

  free_screenlines();

  ScreenLines = new_ScreenLines;
  ScreenLinesUC = new_ScreenLinesUC;
  for (i = 0; i < p_mco; ++i)
    ScreenLinesC[i] = new_ScreenLinesC[i];
  Screen_mco = p_mco;
  ScreenLines2 = new_ScreenLines2;
  ScreenAttrs = new_ScreenAttrs;
  LineOffset = new_LineOffset;
  LineWraps = new_LineWraps;
  TabPageIdxs = new_TabPageIdxs;

  /* It's important that screen_Rows and screen_Columns reflect the actual
   * size of ScreenLines[].  Set them before calling anything. */
  screen_Rows = Rows;
  screen_Columns = Columns;

  must_redraw = CLEAR;          /* need to clear the screen later */
  if (doclear)
    screenclear2();


  entered = FALSE;
  --RedrawingDisabled;

  /*
   * Do not apply autocommands more than 3 times to avoid an endless loop
   * in case applying autocommands always changes Rows or Columns.
   */
  if (starting == 0 && ++retry_count <= 3) {
    apply_autocmds(EVENT_VIMRESIZED, NULL, NULL, FALSE, curbuf);
    /* In rare cases, autocommands may have altered Rows or Columns,
    * jump back to check if we need to allocate the screen again. */
    goto retry;
  }
}

void free_screenlines(void)
{
  int i;

  xfree(ScreenLinesUC);
  for (i = 0; i < Screen_mco; ++i)
    xfree(ScreenLinesC[i]);
  xfree(ScreenLines2);
  xfree(ScreenLines);
  xfree(ScreenAttrs);
  xfree(LineOffset);
  xfree(LineWraps);
  xfree(TabPageIdxs);
}

void screenclear(void)
{
  check_for_delay(FALSE);
  screenalloc(false);       /* allocate screen buffers if size changed */
  screenclear2();           /* clear the screen */
}

static void screenclear2(void)
{
  int i;

  if (starting == NO_SCREEN || ScreenLines == NULL) {
    return;
  }

  screen_stop_highlight();      /* don't want highlighting here */


  /* blank out ScreenLines */
  for (i = 0; i < Rows; ++i) {
    lineclear(LineOffset[i], (int)Columns);
    LineWraps[i] = FALSE;
  }

  ui_clear();  // clear the display
  clear_cmdline = FALSE;
  mode_displayed = FALSE;
  screen_cleared = TRUE;        /* can use contents of ScreenLines now */

  win_rest_invalid(firstwin);
  redraw_cmdline = TRUE;
  redraw_tabline = TRUE;
  if (must_redraw == CLEAR)     /* no need to clear again */
    must_redraw = NOT_VALID;
  compute_cmdrow();
  msg_row = cmdline_row;        /* put cursor on last line for messages */
  msg_col = 0;
  msg_scrolled = 0;             /* can't scroll back */
  msg_didany = FALSE;
  msg_didout = FALSE;
}

/*
 * Clear one line in ScreenLines.
 */
static void lineclear(unsigned off, int width)
{
  (void)memset(ScreenLines + off, ' ', (size_t)width * sizeof(schar_T));
  if (enc_utf8)
    (void)memset(ScreenLinesUC + off, 0,
        (size_t)width * sizeof(u8char_T));
  (void)memset(ScreenAttrs + off, 0, (size_t)width * sizeof(sattr_T));
}

/*
 * Copy part of a Screenline for vertically split window "wp".
 */
static void linecopy(int to, int from, win_T *wp)
{
  unsigned off_to = LineOffset[to] + wp->w_wincol;
  unsigned off_from = LineOffset[from] + wp->w_wincol;

  memmove(ScreenLines + off_to, ScreenLines + off_from,
      wp->w_width * sizeof(schar_T));
  if (enc_utf8) {
    int i;

    memmove(ScreenLinesUC + off_to, ScreenLinesUC + off_from,
        wp->w_width * sizeof(u8char_T));
    for (i = 0; i < p_mco; ++i)
      memmove(ScreenLinesC[i] + off_to, ScreenLinesC[i] + off_from,
          wp->w_width * sizeof(u8char_T));
  }
  if (enc_dbcs == DBCS_JPNU)
    memmove(ScreenLines2 + off_to, ScreenLines2 + off_from,
        wp->w_width * sizeof(schar_T));
  memmove(ScreenAttrs + off_to, ScreenAttrs + off_from,
      wp->w_width * sizeof(sattr_T));
}

/*
 * Set cursor to its position in the current window.
 */
void setcursor(void)
{
  if (redrawing()) {
    validate_cursor();
    ui_cursor_goto(curwin->w_winrow + curwin->w_wrow,
        curwin->w_wincol + (
          /* With 'rightleft' set and the cursor on a double-wide
           * character, position it on the leftmost column. */
          curwin->w_p_rl ? (curwin->w_width - curwin->w_wcol - (
                              (has_mbyte
                               && (*mb_ptr2cells)(get_cursor_pos_ptr()) == 2
                               && vim_isprintc(gchar_cursor())) ? 2 :
                              1)) :
          curwin->w_wcol));
  }
}

/*
 * insert 'line_count' lines at 'row' in window 'wp'
 * if 'invalid' is TRUE the wp->w_lines[].wl_lnum is invalidated.
 * if 'mayclear' is TRUE the screen will be cleared if it is faster than
 * scrolling.
 * Returns FAIL if the lines are not inserted, OK for success.
 */
int win_ins_lines(win_T *wp, int row, int line_count, int invalid, int mayclear)
{
  int did_delete;
  int nextrow;
  int lastrow;
  int retval;

  if (invalid)
    wp->w_lines_valid = 0;

  if (wp->w_height < 5)
    return FAIL;

  if (line_count > wp->w_height - row)
    line_count = wp->w_height - row;

  retval = win_do_lines(wp, row, line_count, mayclear, FALSE);
  if (retval != MAYBE)
    return retval;

  /*
   * If there is a next window or a status line, we first try to delete the
   * lines at the bottom to avoid messing what is after the window.
   * If this fails and there are following windows, don't do anything to avoid
   * messing up those windows, better just redraw.
   */
  did_delete = FALSE;
  if (wp->w_next != NULL || wp->w_status_height) {
    if (screen_del_lines(0, wp->w_winrow + wp->w_height - line_count,
            line_count, (int)Rows, NULL) == OK)
      did_delete = TRUE;
    else if (wp->w_next)
      return FAIL;
  }
  /*
   * if no lines deleted, blank the lines that will end up below the window
   */
  if (!did_delete) {
    wp->w_redr_status = TRUE;
    redraw_cmdline = TRUE;
    nextrow = wp->w_winrow + wp->w_height + wp->w_status_height;
    lastrow = nextrow + line_count;
    if (lastrow > Rows)
      lastrow = Rows;
    screen_fill(nextrow - line_count, lastrow - line_count,
                wp->w_wincol, W_ENDCOL(wp),
                ' ', ' ', 0);
  }

  if (screen_ins_lines(0, wp->w_winrow + row, line_count, (int)Rows, NULL)
      == FAIL) {
    /* deletion will have messed up other windows */
    if (did_delete) {
      wp->w_redr_status = TRUE;
      win_rest_invalid(wp->w_next);
    }
    return FAIL;
  }

  return OK;
}

/*
 * delete "line_count" window lines at "row" in window "wp"
 * If "invalid" is TRUE curwin->w_lines[] is invalidated.
 * If "mayclear" is TRUE the screen will be cleared if it is faster than
 * scrolling
 * Return OK for success, FAIL if the lines are not deleted.
 */
int win_del_lines(win_T *wp, int row, int line_count, int invalid, int mayclear)
{
  int retval;

  if (invalid)
    wp->w_lines_valid = 0;

  if (line_count > wp->w_height - row)
    line_count = wp->w_height - row;

  retval = win_do_lines(wp, row, line_count, mayclear, TRUE);
  if (retval != MAYBE)
    return retval;

  if (screen_del_lines(0, wp->w_winrow + row, line_count,
          (int)Rows, NULL) == FAIL) {
    return FAIL;
  }

  /*
   * If there are windows or status lines below, try to put them at the
   * correct place. If we can't do that, they have to be redrawn.
   */
  if (wp->w_next || wp->w_status_height || cmdline_row < Rows - 1) {
    if (screen_ins_lines(0, wp->w_winrow + wp->w_height - line_count,
            line_count, (int)Rows, NULL) == FAIL) {
      wp->w_redr_status = TRUE;
      win_rest_invalid(wp->w_next);
    }
  }
  /*
   * If this is the last window and there is no status line, redraw the
   * command line later.
   */
  else
    redraw_cmdline = TRUE;
  return OK;
}

// Common code for win_ins_lines() and win_del_lines().
// Returns OK or FAIL when the work has been done.
static int win_do_lines(win_T *wp, int row, int line_count, int mayclear, int del)
{
  if (!redrawing() || line_count <= 0) {
    return FAIL;
  }

  // only a few lines left: redraw is faster
  if (mayclear && Rows - line_count < 5 && wp->w_width == Columns) {
    screenclear();          /* will set wp->w_lines_valid to 0 */
    return FAIL;
  }

  // Delete all remaining lines
  if (row + line_count >= wp->w_height) {
    screen_fill(wp->w_winrow + row, wp->w_winrow + wp->w_height,
                wp->w_wincol, W_ENDCOL(wp),
                ' ', ' ', 0);
    return OK;
  }

  // when scrolling, the message on the command line should be cleared,
  // otherwise it will stay there forever.
  clear_cmdline = TRUE;
  int retval;
  ui_set_scroll_region(wp, row);
  if (del) {
    retval = screen_del_lines(wp->w_winrow + row, 0, line_count,
        wp->w_height - row, wp);
  } else {
    retval = screen_ins_lines(wp->w_winrow + row, 0, line_count,
        wp->w_height - row, wp);
  }
  ui_reset_scroll_region();
  return retval;
}

/*
 * window 'wp' and everything after it is messed up, mark it for redraw
 */
static void win_rest_invalid(win_T *wp)
{
  while (wp != NULL) {
    redraw_win_later(wp, NOT_VALID);
    wp->w_redr_status = TRUE;
    wp = wp->w_next;
  }
  redraw_cmdline = TRUE;
}

/*
 * The rest of the routines in this file perform screen manipulations. The
 * given operation is performed physically on the screen. The corresponding
 * change is also made to the internal screen image. In this way, the editor
 * anticipates the effect of editing changes on the appearance of the screen.
 * That way, when we call screenupdate a complete redraw isn't usually
 * necessary. Another advantage is that we can keep adding code to anticipate
 * screen changes, and in the meantime, everything still works.
 */


// insert lines on the screen and update ScreenLines[]
// 'end' is the line after the scrolled part. Normally it is Rows.
// When scrolling region used 'off' is the offset from the top for the region.
// 'row' and 'end' are relative to the start of the region.
//
// return FAIL for failure, OK for success.
int screen_ins_lines (
    int off,
    int row,
    int line_count,
    int end,
    win_T *wp            /* NULL or window to use width from */
)
{
  int i;
  int j;
  unsigned temp;

  if (!screen_valid(TRUE) || line_count <= 0) {
    return FAIL;
  }

  // Shift LineOffset[] line_count down to reflect the inserted lines.
  // Clear the inserted lines in ScreenLines[].
  row += off;
  end += off;
  for (i = 0; i < line_count; ++i) {
    if (wp != NULL && wp->w_width != Columns) {
      // need to copy part of a line
      j = end - 1 - i;
      while ((j -= line_count) >= row) {
        linecopy(j + line_count, j, wp);
      }
      j += line_count;
      lineclear(LineOffset[j] + wp->w_wincol, wp->w_width);
      LineWraps[j] = FALSE;
    } else {
      j = end - 1 - i;
      temp = LineOffset[j];
      while ((j -= line_count) >= row) {
        LineOffset[j + line_count] = LineOffset[j];
        LineWraps[j + line_count] = LineWraps[j];
      }
      LineOffset[j + line_count] = temp;
      LineWraps[j + line_count] = FALSE;
      lineclear(temp, (int)Columns);
    }
  }

  ui_append_lines(line_count);

  return OK;
}

// delete lines on the screen and update ScreenLines[]
// 'end' is the line after the scrolled part. Normally it is Rows.
// When scrolling region used 'off' is the offset from the top for the region.
// 'row' and 'end' are relative to the start of the region.
//
// Return OK for success, FAIL if the lines are not deleted.
int screen_del_lines (
    int off,
    int row,
    int line_count,
    int end,
    win_T *wp         /* NULL or window to use width from */
)
{
  int j;
  int i;
  unsigned temp;

  if (!screen_valid(TRUE) || line_count <= 0) {
    return FAIL;
  }

  // Now shift LineOffset[] line_count up to reflect the deleted lines.
  // Clear the inserted lines in ScreenLines[].
  row += off;
  end += off;
  for (i = 0; i < line_count; ++i) {
    if (wp != NULL && wp->w_width != Columns) {
      // need to copy part of a line
      j = row + i;
      while ((j += line_count) <= end - 1) {
        linecopy(j - line_count, j, wp);
      }
      j -= line_count;
      lineclear(LineOffset[j] + wp->w_wincol, wp->w_width);
      LineWraps[j] = FALSE;
    } else {
      // whole width, moving the line pointers is faster
      j = row + i;
      temp = LineOffset[j];
      while ((j += line_count) <= end - 1) {
        LineOffset[j - line_count] = LineOffset[j];
        LineWraps[j - line_count] = LineWraps[j];
      }
      LineOffset[j - line_count] = temp;
      LineWraps[j - line_count] = FALSE;
      lineclear(temp, (int)Columns);
    }
  }

  ui_delete_lines(line_count);

  return OK;
}

/*
 * show the current mode and ruler
 *
 * If clear_cmdline is TRUE, clear the rest of the cmdline.
 * If clear_cmdline is FALSE there may be a message there that needs to be
 * cleared only if a mode is shown.
 * Return the length of the message (0 if no message).
 */
int showmode(void)
{
  int need_clear;
  int length = 0;
  int do_mode;
  int attr;
  int nwr_save;
  int sub_attr;

  do_mode = ((p_smd && msg_silent == 0)
             && ((State & TERM_FOCUS)
                 || (State & INSERT)
                 || restart_edit
                 || VIsual_active
                 ));
  if (do_mode || Recording) {
    /*
     * Don't show mode right now, when not redrawing or inside a mapping.
     * Call char_avail() only when we are going to show something, because
     * it takes a bit of time.
     */
    if (!redrawing() || (char_avail() && !KeyTyped) || msg_silent != 0) {
      redraw_cmdline = TRUE;                    /* show mode later */
      return 0;
    }

    nwr_save = need_wait_return;

    /* wait a bit before overwriting an important message */
    check_for_delay(FALSE);

    /* if the cmdline is more than one line high, erase top lines */
    need_clear = clear_cmdline;
    if (clear_cmdline && cmdline_row < Rows - 1)
      msg_clr_cmdline();                        /* will reset clear_cmdline */

    /* Position on the last line in the window, column 0 */
    msg_pos_mode();
    attr = hl_attr(HLF_CM);                     /* Highlight mode */
    if (do_mode) {
      MSG_PUTS_ATTR("--", attr);
      // CTRL-X in Insert mode
      if (edit_submode != NULL && !shortmess(SHM_COMPLETIONMENU)) {
        /* These messages can get long, avoid a wrap in a narrow
         * window.  Prefer showing edit_submode_extra. */
        length = (Rows - msg_row) * Columns - 3;
        if (edit_submode_extra != NULL)
          length -= vim_strsize(edit_submode_extra);
        if (length > 0) {
          if (edit_submode_pre != NULL)
            length -= vim_strsize(edit_submode_pre);
          if (length - vim_strsize(edit_submode) > 0) {
            if (edit_submode_pre != NULL)
              msg_puts_attr(edit_submode_pre, attr);
            msg_puts_attr(edit_submode, attr);
          }
          if (edit_submode_extra != NULL) {
            MSG_PUTS_ATTR(" ", attr);              /* add a space in between */
            if ((int)edit_submode_highl < (int)HLF_COUNT)
              sub_attr = hl_attr(edit_submode_highl);
            else
              sub_attr = attr;
            msg_puts_attr(edit_submode_extra, sub_attr);
          }
        }
      } else {
        if (State & TERM_FOCUS) {
          MSG_PUTS_ATTR(_(" TERMINAL"), attr);
        } else if (State & VREPLACE_FLAG)
          MSG_PUTS_ATTR(_(" VREPLACE"), attr);
        else if (State & REPLACE_FLAG)
          MSG_PUTS_ATTR(_(" REPLACE"), attr);
        else if (State & INSERT) {
          if (p_ri)
            MSG_PUTS_ATTR(_(" REVERSE"), attr);
          MSG_PUTS_ATTR(_(" INSERT"), attr);
        } else if (restart_edit == 'I')
          MSG_PUTS_ATTR(_(" (insert)"), attr);
        else if (restart_edit == 'R')
          MSG_PUTS_ATTR(_(" (replace)"), attr);
        else if (restart_edit == 'V')
          MSG_PUTS_ATTR(_(" (vreplace)"), attr);
        if (p_hkmap)
          MSG_PUTS_ATTR(_(" Hebrew"), attr);
        if (p_fkmap)
          MSG_PUTS_ATTR(farsi_text_5, attr);
        if (State & LANGMAP) {
          if (curwin->w_p_arab)
            MSG_PUTS_ATTR(_(" Arabic"), attr);
          else
            MSG_PUTS_ATTR(_(" (lang)"), attr);
        }
        if ((State & INSERT) && p_paste)
          MSG_PUTS_ATTR(_(" (paste)"), attr);

        if (VIsual_active) {
          char *p;

          /* Don't concatenate separate words to avoid translation
           * problems. */
          switch ((VIsual_select ? 4 : 0)
                  + (VIsual_mode == Ctrl_V) * 2
                  + (VIsual_mode == 'V')) {
          case 0: p = N_(" VISUAL"); break;
          case 1: p = N_(" VISUAL LINE"); break;
          case 2: p = N_(" VISUAL BLOCK"); break;
          case 4: p = N_(" SELECT"); break;
          case 5: p = N_(" SELECT LINE"); break;
          default: p = N_(" SELECT BLOCK"); break;
          }
          MSG_PUTS_ATTR(_(p), attr);
        }
        MSG_PUTS_ATTR(" --", attr);
      }

      need_clear = TRUE;
    }
    if (Recording
        && edit_submode == NULL             /* otherwise it gets too long */
        ) {
      MSG_PUTS_ATTR(_("recording"), attr);
      need_clear = TRUE;
    }

    mode_displayed = TRUE;
    if (need_clear || clear_cmdline)
      msg_clr_eos();
    msg_didout = FALSE;                 /* overwrite this message */
    length = msg_col;
    msg_col = 0;
    need_wait_return = nwr_save;        /* never ask for hit-return for this */
  } else if (clear_cmdline && msg_silent == 0)
    /* Clear the whole command line.  Will reset "clear_cmdline". */
    msg_clr_cmdline();

  /* In Visual mode the size of the selected area must be redrawn. */
  if (VIsual_active)
    clear_showcmd();

  /* If the last window has no status line, the ruler is after the mode
   * message and must be redrawn */
  if (redrawing()
      && lastwin->w_status_height == 0
      )
    win_redr_ruler(lastwin, TRUE);
  redraw_cmdline = FALSE;
  clear_cmdline = FALSE;

  return length;
}

/*
 * Position for a mode message.
 */
static void msg_pos_mode(void)
{
  msg_col = 0;
  msg_row = Rows - 1;
}

/*
 * Delete mode message.  Used when ESC is typed which is expected to end
 * Insert mode (but Insert mode didn't end yet!).
 * Caller should check "mode_displayed".
 */
void unshowmode(int force)
{
  /*
   * Don't delete it right now, when not redrawing or inside a mapping.
   */
  if (!redrawing() || (!force && char_avail() && !KeyTyped))
    redraw_cmdline = TRUE;              /* delete mode later */
  else {
    msg_pos_mode();
    if (Recording)
      MSG_PUTS_ATTR(_("recording"), hl_attr(HLF_CM));
    msg_clr_eos();
  }
}

/*
 * Draw the tab pages line at the top of the Vim window.
 */
static void draw_tabline(void)
{
  int tabcount = 0;
  int tabwidth = 0;
  int col = 0;
  int scol = 0;
  int attr;
  win_T       *wp;
  win_T       *cwp;
  int wincount;
  int modified;
  int c;
  int len;
  int attr_sel = hl_attr(HLF_TPS);
  int attr_nosel = hl_attr(HLF_TP);
  int attr_fill = hl_attr(HLF_TPF);
  char_u      *p;
  int room;
  int use_sep_chars = (t_colors < 8
                       );

  redraw_tabline = FALSE;


  if (tabline_height() < 1)
    return;


  /* Init TabPageIdxs[] to zero: Clicking outside of tabs has no effect. */
  for (scol = 0; scol < Columns; ++scol)
    TabPageIdxs[scol] = 0;

  /* Use the 'tabline' option if it's set. */
  if (*p_tal != NUL) {
    int save_called_emsg = called_emsg;

    /* Check for an error.  If there is one we would loop in redrawing the
     * screen.  Avoid that by making 'tabline' empty. */
    called_emsg = FALSE;
    win_redr_custom(NULL, FALSE);
    if (called_emsg)
      set_string_option_direct((char_u *)"tabline", -1,
          (char_u *)"", OPT_FREE, SID_ERROR);
    called_emsg |= save_called_emsg;
  } else {
    FOR_ALL_TABS(tp) {
      ++tabcount;
    }

    if (tabcount > 0) {
      tabwidth = (Columns - 1 + tabcount / 2) / tabcount;
    }

    if (tabwidth < 6) {
      tabwidth = 6;
    }

    attr = attr_nosel;
    tabcount = 0;

    FOR_ALL_TABS(tp) {
      if (col >= Columns - 4) {
        break;
      }

      scol = col;

      if (tp->tp_topframe == topframe)
        attr = attr_sel;
      if (use_sep_chars && col > 0)
        screen_putchar('|', 0, col++, attr);

      if (tp->tp_topframe != topframe)
        attr = attr_nosel;

      screen_putchar(' ', 0, col++, attr);

      if (tp == curtab) {
        cwp = curwin;
        wp = firstwin;
      } else {
        cwp = tp->tp_curwin;
        wp = tp->tp_firstwin;
      }

      modified = FALSE;
      for (wincount = 0; wp != NULL; wp = wp->w_next, ++wincount)
        if (bufIsChanged(wp->w_buffer))
          modified = TRUE;
      if (modified || wincount > 1) {
        if (wincount > 1) {
          vim_snprintf((char *)NameBuff, MAXPATHL, "%d", wincount);
          len = (int)STRLEN(NameBuff);
          if (col + len >= Columns - 3)
            break;
          screen_puts_len(NameBuff, len, 0, col,
                          hl_combine_attr(attr, hl_attr(HLF_T)));
          col += len;
        }
        if (modified)
          screen_puts_len((char_u *)"+", 1, 0, col++, attr);
        screen_putchar(' ', 0, col++, attr);
      }

      room = scol - col + tabwidth - 1;
      if (room > 0) {
        /* Get buffer name in NameBuff[] */
        get_trans_bufname(cwp->w_buffer);
        (void)shorten_dir(NameBuff);
        len = vim_strsize(NameBuff);
        p = NameBuff;
        if (has_mbyte)
          while (len > room) {
            len -= ptr2cells(p);
            mb_ptr_adv(p);
          }
        else if (len > room) {
          p += len - room;
          len = room;
        }
        if (len > Columns - col - 1)
          len = Columns - col - 1;

        screen_puts_len(p, (int)STRLEN(p), 0, col, attr);
        col += len;
      }
      screen_putchar(' ', 0, col++, attr);

      /* Store the tab page number in TabPageIdxs[], so that
       * jump_to_mouse() knows where each one is. */
      ++tabcount;
      while (scol < col)
        TabPageIdxs[scol++] = tabcount;
    }

    if (use_sep_chars)
      c = '_';
    else
      c = ' ';
    screen_fill(0, 1, col, (int)Columns, c, c, attr_fill);

    /* Put an "X" for closing the current tab if there are several. */
    if (first_tabpage->tp_next != NULL) {
      screen_putchar('X', 0, (int)Columns - 1, attr_nosel);
      TabPageIdxs[Columns - 1] = -999;
    }
  }

  /* Reset the flag here again, in case evaluating 'tabline' causes it to be
   * set. */
  redraw_tabline = FALSE;
}

/*
 * Get buffer name for "buf" into NameBuff[].
 * Takes care of special buffer names and translates special characters.
 */
void get_trans_bufname(buf_T *buf)
{
  if (buf_spname(buf) != NULL)
    STRLCPY(NameBuff, buf_spname(buf), MAXPATHL);
  else
    home_replace(buf, buf->b_fname, NameBuff, MAXPATHL, TRUE);
  trans_characters(NameBuff, MAXPATHL);
}

/*
 * Get the character to use in a status line.  Get its attributes in "*attr".
 */
static int fillchar_status(int *attr, int is_curwin)
{
  int fill;
  if (is_curwin) {
    *attr = hl_attr(HLF_S);
    fill = fill_stl;
  } else {
    *attr = hl_attr(HLF_SNC);
    fill = fill_stlnc;
  }
  /* Use fill when there is highlighting, and highlighting of current
   * window differs, or the fillchars differ, or this is not the
   * current window */
  if (*attr != 0 && ((hl_attr(HLF_S) != hl_attr(HLF_SNC)
                      || !is_curwin || firstwin == lastwin)
                     || (fill_stl != fill_stlnc)))
    return fill;
  if (is_curwin)
    return '^';
  return '=';
}

/*
 * Get the character to use in a separator between vertically split windows.
 * Get its attributes in "*attr".
 */
static int fillchar_vsep(int *attr)
{
  *attr = hl_attr(HLF_C);
  if (*attr == 0 && fill_vert == ' ')
    return '|';
  else
    return fill_vert;
}

/*
 * Return TRUE if redrawing should currently be done.
 */
int redrawing(void)
{
  return !RedrawingDisabled
         && !(p_lz && char_avail() && !KeyTyped && !do_redraw);
}

/*
 * Return TRUE if printing messages should currently be done.
 */
int messaging(void)
{
  return !(p_lz && char_avail() && !KeyTyped);
}

/*
 * Show current status info in ruler and various other places
 * If always is FALSE, only show ruler if position has changed.
 */
void showruler(int always)
{
  if (!always && !redrawing())
    return;
  if (pum_visible()) {
    /* Don't redraw right now, do it later. */
    curwin->w_redr_status = TRUE;
    return;
  }
  if ((*p_stl != NUL || *curwin->w_p_stl != NUL) && curwin->w_status_height) {
    redraw_custom_statusline(curwin);
  } else
    win_redr_ruler(curwin, always);

  if (need_maketitle
      || (p_icon && (stl_syntax & STL_IN_ICON))
      || (p_title && (stl_syntax & STL_IN_TITLE))
      )
    maketitle();
  /* Redraw the tab pages line if needed. */
  if (redraw_tabline)
    draw_tabline();
}

static void win_redr_ruler(win_T *wp, int always)
{
  /* If 'ruler' off or redrawing disabled, don't do anything */
  if (!p_ru)
    return;

  /*
   * Check if cursor.lnum is valid, since win_redr_ruler() may be called
   * after deleting lines, before cursor.lnum is corrected.
   */
  if (wp->w_cursor.lnum > wp->w_buffer->b_ml.ml_line_count)
    return;

  /* Don't draw the ruler while doing insert-completion, it might overwrite
   * the (long) mode message. */
  if (wp == lastwin && lastwin->w_status_height == 0)
    if (edit_submode != NULL)
      return;
  /* Don't draw the ruler when the popup menu is visible, it may overlap. */
  if (pum_visible())
    return;

  if (*p_ruf) {
    int save_called_emsg = called_emsg;

    called_emsg = FALSE;
    win_redr_custom(wp, TRUE);
    if (called_emsg)
      set_string_option_direct((char_u *)"rulerformat", -1,
          (char_u *)"", OPT_FREE, SID_ERROR);
    called_emsg |= save_called_emsg;
    return;
  }

  /*
   * Check if not in Insert mode and the line is empty (will show "0-1").
   */
  int empty_line = FALSE;
  if (!(State & INSERT)
      && *ml_get_buf(wp->w_buffer, wp->w_cursor.lnum, FALSE) == NUL)
    empty_line = TRUE;

  /*
   * Only draw the ruler when something changed.
   */
  validate_virtcol_win(wp);
  if (       redraw_cmdline
             || always
             || wp->w_cursor.lnum != wp->w_ru_cursor.lnum
             || wp->w_cursor.col != wp->w_ru_cursor.col
             || wp->w_virtcol != wp->w_ru_virtcol
             || wp->w_cursor.coladd != wp->w_ru_cursor.coladd
             || wp->w_topline != wp->w_ru_topline
             || wp->w_buffer->b_ml.ml_line_count != wp->w_ru_line_count
             || wp->w_topfill != wp->w_ru_topfill
             || empty_line != wp->w_ru_empty) {

    int width;
    int row;
    int fillchar;
    int attr;
    int off;

    if (wp->w_status_height) {
      row = wp->w_winrow + wp->w_height;
      fillchar = fillchar_status(&attr, wp == curwin);
      off = wp->w_wincol;
      width = wp->w_width;
    } else {
      row = Rows - 1;
      fillchar = ' ';
      attr = 0;
      width = Columns;
      off = 0;
    }

    /* In list mode virtcol needs to be recomputed */
    colnr_T virtcol = wp->w_virtcol;
    if (wp->w_p_list && lcs_tab1 == NUL) {
      wp->w_p_list = FALSE;
      getvvcol(wp, &wp->w_cursor, NULL, &virtcol, NULL);
      wp->w_p_list = TRUE;
    }

#define RULER_BUF_LEN 70
    char_u buffer[RULER_BUF_LEN];

    /*
     * Some sprintfs return the length, some return a pointer.
     * To avoid portability problems we use strlen() here.
     */
    vim_snprintf((char *)buffer, RULER_BUF_LEN, "%" PRId64 ",",
        (wp->w_buffer->b_ml.ml_flags & ML_EMPTY) ? (int64_t)0L
                                                 : (int64_t)wp->w_cursor.lnum);
    size_t len = STRLEN(buffer);
    col_print(buffer + len, RULER_BUF_LEN - len,
        empty_line ? 0 : (int)wp->w_cursor.col + 1,
        (int)virtcol + 1);

    /*
     * Add a "50%" if there is room for it.
     * On the last line, don't print in the last column (scrolls the
     * screen up on some terminals).
     */
    int i = (int)STRLEN(buffer);
    get_rel_pos(wp, buffer + i + 1, RULER_BUF_LEN - i - 1);
    int o = i + vim_strsize(buffer + i + 1);
    if (wp->w_status_height == 0)       /* can't use last char of screen */
      ++o;
    int this_ru_col = ru_col - (Columns - width);
    if (this_ru_col < 0)
      this_ru_col = 0;
    /* Never use more than half the window/screen width, leave the other
     * half for the filename. */
    if (this_ru_col < (width + 1) / 2)
      this_ru_col = (width + 1) / 2;
    if (this_ru_col + o < width) {
      // Need at least 3 chars left for get_rel_pos() + NUL.
      while (this_ru_col + o < width && RULER_BUF_LEN > i + 4) {
        if (has_mbyte)
          i += (*mb_char2bytes)(fillchar, buffer + i);
        else
          buffer[i++] = fillchar;
        ++o;
      }
      get_rel_pos(wp, buffer + i, RULER_BUF_LEN - i);
    }
    /* Truncate at window boundary. */
    if (has_mbyte) {
      o = 0;
      for (i = 0; buffer[i] != NUL; i += (*mb_ptr2len)(buffer + i)) {
        o += (*mb_ptr2cells)(buffer + i);
        if (this_ru_col + o > width) {
          buffer[i] = NUL;
          break;
        }
      }
    } else if (this_ru_col + (int)STRLEN(buffer) > width)
      buffer[width - this_ru_col] = NUL;

    screen_puts(buffer, row, this_ru_col + off, attr);
    i = redraw_cmdline;
    screen_fill(row, row + 1,
        this_ru_col + off + (int)STRLEN(buffer),
        off + width,
        fillchar, fillchar, attr);
    /* don't redraw the cmdline because of showing the ruler */
    redraw_cmdline = i;
    wp->w_ru_cursor = wp->w_cursor;
    wp->w_ru_virtcol = wp->w_virtcol;
    wp->w_ru_empty = empty_line;
    wp->w_ru_topline = wp->w_topline;
    wp->w_ru_line_count = wp->w_buffer->b_ml.ml_line_count;
    wp->w_ru_topfill = wp->w_topfill;
  }
}

/*
 * Return the width of the 'number' and 'relativenumber' column.
 * Caller may need to check if 'number' or 'relativenumber' is set.
 * Otherwise it depends on 'numberwidth' and the line count.
 */
int number_width(win_T *wp)
{
  int n;
  linenr_T lnum;

  if (wp->w_p_rnu && !wp->w_p_nu)
    /* cursor line shows "0" */
    lnum = wp->w_height;
  else
    /* cursor line shows absolute line number */
    lnum = wp->w_buffer->b_ml.ml_line_count;

  if (lnum == wp->w_nrwidth_line_count)
    return wp->w_nrwidth_width;
  wp->w_nrwidth_line_count = lnum;

  n = 0;
  do {
    lnum /= 10;
    ++n;
  } while (lnum > 0);

  /* 'numberwidth' gives the minimal width plus one */
  if (n < wp->w_p_nuw - 1)
    n = wp->w_p_nuw - 1;

  wp->w_nrwidth_width = n;
  return n;
}

/*
 * Set size of the Vim shell.
 * If 'mustset' is TRUE, we must set Rows and Columns, do not get the real
 * window size (this is used for the :win command).
 * If 'mustset' is FALSE, we may try to get the real window size and if
 * it fails use 'width' and 'height'.
 */
void screen_resize(int width, int height)
{
  static int busy = FALSE;

  /*
   * Avoid recursiveness, can happen when setting the window size causes
   * another window-changed signal.
   */
  if (busy)
    return;

  if (width < 0 || height < 0)      /* just checking... */
    return;

  if (State == HITRETURN || State == SETWSIZE) {
    /* postpone the resizing */
    State = SETWSIZE;
    return;
  }

  /* curwin->w_buffer can be NULL when we are closing a window and the
   * buffer has already been closed and removing a scrollbar causes a resize
   * event. Don't resize then, it will happen after entering another buffer.
   */
  if (curwin->w_buffer == NULL)
    return;

  ++busy;

  Rows = height;
  Columns = width;
  check_shellsize();
  height = Rows;
  width = Columns;
  ui_resize(width, height);

  /* The window layout used to be adjusted here, but it now happens in
   * screenalloc() (also invoked from screenclear()).  That is because the
   * "busy" check above may skip this, but not screenalloc(). */

  if (State != ASKMORE && State != EXTERNCMD && State != CONFIRM) {
    screenclear();
  }

  if (starting != NO_SCREEN) {
    maketitle();
    changed_line_abv_curs();
    invalidate_botline();

    /*
     * We only redraw when it's needed:
     * - While at the more prompt or executing an external command, don't
     *   redraw, but position the cursor.
     * - While editing the command line, only redraw that.
     * - in Ex mode, don't redraw anything.
     * - Otherwise, redraw right now, and position the cursor.
     * Always need to call update_screen() or screenalloc(), to make
     * sure Rows/Columns and the size of ScreenLines[] is correct!
     */
    if (State == ASKMORE || State == EXTERNCMD || State == CONFIRM
        || exmode_active) {
      screenalloc(false);
      repeat_message();
    } else {
      if (curwin->w_p_scb)
        do_check_scrollbind(TRUE);
      if (State & CMDLINE) {
        update_screen(NOT_VALID);
        redrawcmdline();
      } else {
        update_topline();
        if (pum_visible()) {
          redraw_later(NOT_VALID);
          ins_compl_show_pum();           /* This includes the redraw. */
        } else
          update_screen(NOT_VALID);
        if (redrawing())
          setcursor();
      }
    }
  }
  ui_flush();
  --busy;
}

// Check if the new shell size is valid, correct it if it's too small or way
// too big.
void check_shellsize(void)
{
  if (Rows < min_rows()) {
    // need room for one window and command line
    Rows = min_rows();
  }
  limit_screen_size();
}

// Limit Rows and Columns to avoid an overflow in Rows * Columns.
void limit_screen_size(void)
{
  if (Columns < MIN_COLUMNS) {
    Columns = MIN_COLUMNS;
  } else if (Columns > 10000) {
    Columns = 10000;
  }

  if (Rows > 1000) {
    Rows = 1000;
  }
}

void win_new_shellsize(void)
{
  static long old_Rows = 0;
  static long old_Columns = 0;

  if (old_Rows != Rows) {
    // if 'window' uses the whole screen, keep it using that */
    if (p_window == old_Rows - 1 || old_Rows == 0) {
      p_window = Rows - 1;
    }
    old_Rows = Rows;
    shell_new_rows();  // update window sizes
  }
  if (old_Columns != Columns) {
    old_Columns = Columns;
    shell_new_columns();  // update window sizes
  }
}
