/* vi:set ts=8 sts=4 sw=4 noet:
 *
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * edit.c: functions for Insert mode
 */

#include "vim.h"

#define BACKSPACE_CHAR 1
#define BACKSPACE_WORD 2
#define BACKSPACE_WORD_NOT_SPACE 3
#define BACKSPACE_LINE 4

static void ins_ctrl_v(void);
#ifdef FEAT_JOB_CHANNEL
static void init_prompt(int cmdchar_todo);
#endif
static void undisplay_dollar(void);
static void insert_special(int, int, int);
static void internal_format(int textwidth, int second_indent, int flags,
                            int format_only, int c);
static void check_auto_format(int);
static void redo_literal(int c);
static void start_arrow_common(pos_T *end_insert_pos, int change);
static void stop_insert(pos_T *end_insert_pos, int esc, int nomove);
static int echeck_abbr(int);
static void replace_join(int off);
static void mb_replace_pop_ins(int cc);
static void replace_flush(void);
static void replace_do_bs(int limit_col);
static int del_char_after_col(int limit_col);
static void ins_ctrl_g(void);
static void ins_ctrl_g_nonblocking(int c);
static void ins_ctrl_hat(void);
static int ins_esc(long *count, int cmdchar, int nomove);
#ifdef FEAT_RIGHTLEFT
static void ins_ctrl_(void);
#endif
static int ins_start_select(int c);
static void ins_insert(int replaceState);
static void ins_ctrl_o(void);
static void ins_shift(int c, int lastc);
static void ins_del(void);
static int ins_bs(int c, int mode, int *inserted_space_p);
static void ins_left(void);
static void ins_home(int c);
static void ins_end(int c);
static void ins_s_left(void);
static void ins_right(void);
static void ins_s_right(void);
static void ins_up(int startcol);
static void ins_pageup(void);
static void ins_down(int startcol);
static void ins_pagedown(void);
static int ins_tab(void);
#ifdef FEAT_DIGRAPHS
static int ins_digraph(void);
#endif
static int ins_ctrl_ey(int tc);
#ifdef FEAT_SMARTINDENT
static void ins_try_si(int c);
#endif
#if defined(FEAT_EVAL)
static char_u *do_insert_char_pre(int c);
#endif

static colnr_T Insstart_textlen;        /* length of line when insert started */
static colnr_T Insstart_blank_vcol;     /* vcol for first inserted blank */
static int update_Insstart_orig = TRUE; /* set Insstart_orig to Insstart */

static char_u *last_insert = NULL; /* the text of the previous insert,
                                      K_SPECIAL and CSI are escaped */
static int last_insert_skip;       /* nr of chars in front of previous insert */
static int new_insert_skip;        /* nr of chars in front of current insert */
static int did_restart_edit;       /* "restart_edit" when calling edit() */

static int old_indent = 0; /* for ^^D command in insert mode */

#ifdef FEAT_RIGHTLEFT
static int revins_on;    /* reverse insert mode on */
static int revins_chars; /* how much to skip after edit */
static int revins_legal; /* was the last char 'legal'? */
static int revins_scol;  /* start column of revins session */
#endif

static int ins_need_undo; /* call u_save() before inserting a
                             char.  Set when edit() is called.
                             after that arrow_used is used. */

static int did_add_space = FALSE;  // auto_format() added an extra space
                                   // under the cursor
static int dont_sync_undo = FALSE; // CTRL-G U prevents syncing undo for
                                   // the next left/right cursor key

typedef struct
{
  int cmdchar;
  int startln;
  long count;
  int c;
  char_u *ptr;
  int lastc;
  int mincol;
  int i;
  int did_backspace;
  int line_is_white;
  linenr_T old_topline;
  int old_topfill;
  int inserted_space;
  int replaceState;
  int nomove;
  int cmdchar_todo;
  int is_ctrlv;  /* If we are coming back from inserting a literal */
  int ctrlv_ret; /* Return value from inserting a literal */
  int is_ctrlg;  /* If ctrl-g was pressed last */
} editState_T;

static linenr_T o_lnum = 0;

void *state_edit_initialize(int cmdchar, int startln, long count)
{
  editState_T *context = (editState_T *)alloc(sizeof(editState_T));
  context->cmdchar = cmdchar;
  context->startln = startln;
  context->count = count;
  context->c = 0;
  context->lastc = 0;
  context->old_topline = 0;
  context->old_topfill = -1;
  context->nomove = FALSE;
  context->is_ctrlv = FALSE;
  context->is_ctrlg = FALSE;
  context->ctrlv_ret = 0;

  /* Remember whether editing was restarted after CTRL-O. */
  did_restart_edit = restart_edit;

  /* sleep before redrawing, needed for "CTRL-O :" that results in an
   * error message */
  check_for_delay(TRUE);

  /* set Insstart_orig to Insstart */
  update_Insstart_orig = TRUE;

#ifdef HAVE_SANDBOX
  /* Don't allow inserting in the sandbox. */
  if (sandbox != 0)
  {
    emsg(_(e_sandbox));
    return FALSE;
  }
#endif
  /* Don't allow changes in the buffer while editing the cmdline.  The
   * caller of getcmdline() may get confused. */
  if (textlock != 0)
  {
    emsg(_(e_secure));
    return FALSE;
  }

  /*
   * Trigger InsertEnter autocommands.  Do not do this for "r<CR>" or "grx".
   */
  if (context->cmdchar != 'r' && context->cmdchar != 'v')
  {
    pos_T save_cursor = curwin->w_cursor;

#ifdef FEAT_EVAL
    if (context->cmdchar == 'R')
      context->ptr = (char_u *)"r";
    else if (context->cmdchar == 'V')
      context->ptr = (char_u *)"v";
    else
      context->ptr = (char_u *)"i";
    set_vim_var_string(VV_INSERTMODE, context->ptr, 1);
    set_vim_var_string(VV_CHAR, NULL, -1); /* clear v:char */
#endif
    ins_apply_autocmds(EVENT_INSERTENTER);

    /* Make sure the cursor didn't move.  Do call check_cursor_col() in
     * case the text was modified.  Since Insert mode was not started yet
     * a call to check_cursor_col() may move the cursor, especially with
     * the "A" command, thus set State to avoid that. Also check that the
     * line number is still valid (lines may have been deleted).
     * Do not restore if v:char was set to a non-empty string. */
    if (!EQUAL_POS(curwin->w_cursor, save_cursor)
#ifdef FEAT_EVAL
        && *get_vim_var_str(VV_CHAR) == NUL
#endif
        && save_cursor.lnum <= curbuf->b_ml.ml_line_count)
    {
      int save_state = State;

      curwin->w_cursor = save_cursor;
      State = INSERT;
      check_cursor_col();
      State = save_state;
    }
  }

  {
    Insstart = curwin->w_cursor;
    if (context->startln)
      Insstart.col = 0;
  }
  Insstart_textlen = (colnr_T)linetabsize(ml_get_curline());
  Insstart_blank_vcol = MAXCOL;
  if (!did_ai)
    ai_col = 0;

  if (context->cmdchar != NUL && restart_edit == 0)
  {
    ResetRedobuff();
    AppendNumberToRedobuff(count);
    if (context->cmdchar == 'V' || context->cmdchar == 'v')
    {
      /* "gR" or "gr" command */
      AppendCharToRedobuff('g');
      AppendCharToRedobuff((cmdchar == 'v') ? 'r' : 'R');
    }
    else
    {
      if (context->cmdchar == K_PS)
        AppendCharToRedobuff('a');
      else
        AppendCharToRedobuff(context->cmdchar);
      if (context->cmdchar == 'g') /* "gI" command */
        AppendCharToRedobuff('I');
      else if (context->cmdchar == 'r') /* "r<CR>" command */
        context->count = 1;             /* insert only one <CR> */
    }
  }

  if (context->cmdchar == 'R')
  {
    State = REPLACE;
  }
  else if (context->cmdchar == 'V' || context->cmdchar == 'v')
  {
    State = VREPLACE;
    context->replaceState = VREPLACE;
    orig_line_count = curbuf->b_ml.ml_line_count;
    vr_lines_changed = 1;
  }
  else
    State = INSERT;

  stop_insert_mode = FALSE;

  /*
   * Need to recompute the cursor position, it might move when the cursor is
   * on a TAB or special character.
   */
  curs_columns(TRUE);

  /*
   * Enable langmap or IME, indicated by 'iminsert'.
   * Note that IME may enabled/disabled without us noticing here, thus the
   * 'iminsert' value may not reflect what is actually used.  It is updated
   * when hitting <Esc>.
   */
  if (curbuf->b_p_iminsert == B_IMODE_LMAP)
    State |= LANGMAP;

#ifdef FEAT_RIGHTLEFT
  /* there is no reverse replace mode */
  revins_on = (State == INSERT && p_ri);
  if (revins_on)
    undisplay_dollar();
  revins_chars = 0;
  revins_legal = 0;
  revins_scol = -1;
#endif
  if (!p_ek)
    /* Disable bracketed paste mode, we won't recognize the escape
     * sequences. */
    out_str(T_BD);

  /*
   * Handle restarting Insert mode.
   * Don't do this for "CTRL-O ." (repeat an insert): In that case we get
   * here with something in the stuff buffer.
   */
  if (restart_edit != 0 && stuff_empty())
  {
    arrow_used = TRUE;
    restart_edit = 0;

    /*
     * If the cursor was after the end-of-line before the CTRL-O and it is
     * now at the end-of-line, put it after the end-of-line (this is not
     * correct in very rare cases).
     * Also do this if curswant is greater than the current virtual
     * column.  Eg after "^O$" or "^O80|".
     */
    validate_virtcol();
    update_curswant();
    if (((ins_at_eol && curwin->w_cursor.lnum == o_lnum) ||
         curwin->w_curswant > curwin->w_virtcol) &&
        *(context->ptr = ml_get_curline() + curwin->w_cursor.col) != NUL)
    {
      if (context->ptr[1] == NUL)
        ++curwin->w_cursor.col;
      else if (has_mbyte)
      {
        context->i = (*mb_ptr2len)(context->ptr);
        if (context->ptr[context->i] == NUL)
          curwin->w_cursor.col += context->i;
      }
    }
    ins_at_eol = FALSE;
  }
  else
    arrow_used = FALSE;

  /* we are in insert mode now, don't need to start it anymore */
  need_start_insertmode = FALSE;

  /* Need to save the line for undo before inserting the first char. */
  ins_need_undo = TRUE;

#ifdef FEAT_FOLDING
  /* The cursor line is not in a closed fold, unless 'insertmode' is set or
   * restarting. */
  if (!p_im && did_restart_edit == 0)
    foldOpenCursor();
#endif

  /*
   * If 'showmode' is set, show the current (insert/replace/..) mode.
   * A warning message for changing a readonly file is given here, before
   * actually changing anything.  It's put after the mode, if any.
   */
  context->i = 0;

  if (!p_im && did_restart_edit == 0)
    change_warning(context->i == 0 ? 0 : context->i + 1);

#ifdef FEAT_DIGRAPHS
  do_digraph(-1); /* clear digraphs */
#endif

  /*
   * Get the current length of the redo buffer, those characters have to be
   * skipped if we want to get to the inserted characters.
   */
  context->ptr = get_inserted();
  if (context->ptr == NULL)
    new_insert_skip = 0;
  else
  {
    new_insert_skip = (int)STRLEN(context->ptr);
    vim_free(context->ptr);
  }

  old_indent = 0;
  return (void *)context;
}

void state_edit_cleanup(void *ctx)
{
  editState_T *context = (editState_T *)ctx;
  vim_free(context);
}

executionStatus_T state_edit_execute(void *ctx, int c)
{
  editState_T *context = (editState_T *)ctx;

  /* If we are coming back ctrl-v, handle that */

  if (context->is_ctrlv)
  {
    insert_special(context->ctrlv_ret, FALSE, TRUE);
#ifdef FEAT_RIGHTLEFT
    revins_chars++;
    revins_legal++;
#endif
    context->is_ctrlv = FALSE;
    return HANDLED;
  }

  if (context->is_ctrlg)
  {
    ins_ctrl_g_nonblocking(c);
    context->is_ctrlg = FALSE;
    return HANDLED;
  }

#ifdef FEAT_RIGHTLEFT
  if (!revins_legal)
    revins_scol = -1; /* reset on illegal motions */
  else
    revins_legal = 0;
#endif
  if (arrow_used) /* don't repeat insert when arrow key used */
    context->count = 0;

  if (update_Insstart_orig)
    Insstart_orig = Insstart;

  if (stop_insert_mode)
  {
    /* ":stopinsert" used or 'insertmode' reset */
    context->count = 0;
    goto doESCkey;
  }

  /* set curwin->w_curswant for next K_DOWN or K_UP */
  if (!arrow_used)
    curwin->w_set_curswant = TRUE;

  /* If there is no typeahead may check for timestamps (e.g., for when a
   * menu invoked a shell command). */
  if (stuff_empty())
  {
    did_check_timestamps = FALSE;
    if (need_check_timestamps)
      check_timestamps(FALSE);
  }

  /*
   * When emsg() was called msg_scroll will have been set.
   */
  msg_scroll = FALSE;

#ifdef FEAT_FOLDING
  /* Open fold at the cursor line, according to 'foldopen'. */
  if (fdo_flags & FDO_INSERT)
    foldOpenCursor();
  /* Close folds where the cursor isn't, according to 'foldclose' */
  if (!char_avail())
    foldCheckClose();
#endif

#ifdef FEAT_JOB_CHANNEL
  if (bt_prompt(curbuf))
  {
    init_prompt(context->cmdchar_todo);
    context->cmdchar_todo = NUL;
  }
#endif

  context->did_backspace = FALSE;

  validate_cursor(); /* may set must_redraw */

  if (curwin->w_p_scb)
    do_check_scrollbind(TRUE);

  if (curwin->w_p_crb)
    do_check_cursorbind();
  update_curswant();
  context->old_topline = curwin->w_topline;
#ifdef FEAT_DIFF
  context->old_topfill = curwin->w_topfill;
#endif

  /*
   * Get a character for Insert mode.  Ignore K_IGNORE and K_NOP.
   */
  if (c != K_CURSORHOLD)
    context->lastc = c; /* remember the previous char for CTRL-D */

  /* After using CTRL-G U the next cursor key will not break undo. */
  if (dont_sync_undo == MAYBE)
    dont_sync_undo = TRUE;
  else
    dont_sync_undo = FALSE;
  if (context->cmdchar == K_PS)
    /* Got here from normal mode when bracketed paste started. */
    c = K_PS;
  /* else */
  /* TODO: Is this needed? Where do K_IGNORE and K_NOP come from ?*/
  /* do */
  /* { */
  /* c = safe_vgetc(); */

  /* if (stop_insert_mode) */
  /* { */
  /* // Insert mode ended, possibly from a callback. */
  /* count = 0; */
  /* nomove = TRUE; */
  /* goto doESCkey; */
  /* } */
  /* } while (c == K_IGNORE || c == K_NOP); */

  /* Don't want K_CURSORHOLD for the second key, e.g., after CTRL-V. */
  did_cursorhold = TRUE;

#ifdef FEAT_RIGHTLEFT
  if (p_hkmap && KeyTyped)
    c = hkmap(c); /* Hebrew mode mapping */
#endif

    /* CTRL-\ CTRL-N goes to Normal mode,
     * CTRL-\ CTRL-G goes to mode selected with 'insertmode',
     * CTRL-\ CTRL-O is like CTRL-O but without moving the cursor.  */
    /* TODO: Bring back this logic */
    /* if (c == Ctrl_BSL) */
    /* { */
    /*     /1* may need to redraw when no more chars available now *1/ */
    /*     ins_redraw(FALSE); */
    /*     ++no_mapping; */
    /*     ++allow_keys; */
    /*     c = plain_vgetc(); */
    /*     --no_mapping; */
    /*     --allow_keys; */
    /*     if (c != Ctrl_N && c != Ctrl_G && c != Ctrl_O) */
    /*     { */
    /* 	/1* it's something else *1/ */
    /* 	vungetc(c); */
    /* 	c = Ctrl_BSL; */
    /*     } */
    /*     else if (c == Ctrl_G && p_im) */
    /* 	continue; */
    /*     else */
    /*     { */
    /* 	if (c == Ctrl_O) */
    /* 	{ */
    /* 	    ins_ctrl_o(); */
    /* 	    ins_at_eol = FALSE;	/1* cursor keeps its column *1/ */
    /* 	    nomove = TRUE; */
    /* 	} */
    /* 	count = 0; */
    /* 	goto doESCkey; */
    /*     } */
    /* } */

#ifdef FEAT_DIGRAPHS
  c = do_digraph(c);
#endif

  if (c == Ctrl_V || c == Ctrl_Q)
  {
    context->is_ctrlv = TRUE;
    context->c = Ctrl_V; /* pretend CTRL-V is last typed character */
    sm_push_insert_literal(&context->ctrlv_ret);
    return HANDLED;
  }

#ifdef FEAT_RIGHTLEFT
  if (curwin->w_p_rl)
    switch (c)
    {
    case K_LEFT:
      c = K_RIGHT;
      break;
    case K_S_LEFT:
      c = K_S_RIGHT;
      break;
    case K_C_LEFT:
      c = K_C_RIGHT;
      break;
    case K_RIGHT:
      c = K_LEFT;
      break;
    case K_S_RIGHT:
      c = K_S_LEFT;
      break;
    case K_C_RIGHT:
      c = K_C_LEFT;
      break;
    }
#endif

  /*
   * If 'keymodel' contains "startsel", may start selection.  If it
   * does, a CTRL-O and c will be stuffed, we need to get these
   * characters.
   */
  if (ins_start_select(c))
    return HANDLED;

  /*
   * The big switch to handle a character in insert mode.
   */
  switch (c)
  {
  case ESC: /* End input mode */
    if (echeck_abbr(ESC + ABBR_OFF))
      break;
    /* FALLTHROUGH */

  case Ctrl_C: /* End input mode */
#ifdef FEAT_JOB_CHANNEL
    if (c == Ctrl_C && bt_prompt(curbuf))
    {
      if (invoke_prompt_interrupt())
      {
        if (!bt_prompt(curbuf))
          // buffer changed to a non-prompt buffer, get out of
          // Insert mode
          goto doESCkey;
        break;
      }
    }
#endif

#ifdef UNIX
    /* Suppress unused-label error */
    goto do_intr;
  do_intr:
#endif
    /* when 'insertmode' set, and not halfway a mapping, don't leave
     * Insert mode */
    /* TODO: What is this used for? */
    /* if (goto_im()) */
    /* { */
    /* if (got_int) */
    /* { */
    /* (void)vgetc();		/1* flush all buffers *1/ */
    /* got_int = FALSE; */
    /* } */
    /* else */
    /* vim_beep(BO_IM); */
    /* break; */
    /* } */
  doESCkey:
    /*
     * This is the ONLY return from edit()!
     */
    /* Always update o_lnum, so that a "CTRL-O ." that adds a line
     * still puts the cursor back after the inserted text. */
    if (ins_at_eol && gchar_cursor() == NUL)
      o_lnum = curwin->w_cursor.lnum;

    if (ins_esc(&context->count, context->cmdchar, context->nomove))
    {
      // When CTRL-C was typed got_int will be set, with the result
      // that the autocommands won't be executed. When mapped got_int
      // is not set, but let's keep the behavior the same.
      if (context->cmdchar != 'r' && context->cmdchar != 'v' && c != Ctrl_C)
        ins_apply_autocmds(EVENT_INSERTLEAVE);
      did_cursorhold = FALSE;
      return COMPLETED;
      /* TODO: Handle Ctrl_O */
      /* return (c == Ctrl_O); */
    }
    else
    {
      return HANDLED;
    }

  case Ctrl_Z: /* suspend when 'insertmode' set */
    if (!p_im)
      goto normalchar; /* insert CTRL-Z as normal char */
    do_cmdline_cmd((char_u *)"stop");
    return HANDLED;

  case Ctrl_O: /* execute one command */
    if (echeck_abbr(Ctrl_O + ABBR_OFF))
      break;
    ins_ctrl_o();

    /* don't move the cursor left when 'virtualedit' has "onemore". */
    if (ve_flags & VE_ONEMORE)
    {
      ins_at_eol = FALSE;
      context->nomove = TRUE;
    }
    context->count = 0;
    goto doESCkey;

  case K_INS: /* toggle insert/replace mode */
  case K_KINS:
    ins_insert(context->replaceState);
    break;

  case K_SELECT: /* end of Select mode mapping - ignore */
    break;

  case K_HELP: /* Help key works like <ESC> <Help> */
  case K_F1:
  case K_XF1:
    stuffcharReadbuff(K_HELP);
    if (p_im)
      need_start_insertmode = TRUE;
    goto doESCkey;

  case K_ZERO: /* Insert the previously inserted text. */
  case NUL:
  case Ctrl_A:
    /* For ^@ the trailing ESC will end the insert, unless there is an
     * error.  */
    if (stuff_inserted(NUL, 1L, (c == Ctrl_A)) == FAIL && c != Ctrl_A && !p_im)
      goto doESCkey; /* quit insert mode */
    context->inserted_space = FALSE;
    break;

  case Ctrl_G: /* commands starting with CTRL-G */
    // Mark as in 'ctrlg' mode, handle next key
    context->is_ctrlg = TRUE;
    break;

  case Ctrl_HAT: /* switch input mode and/or langmap */
    ins_ctrl_hat();
    break;

#ifdef FEAT_RIGHTLEFT
  case Ctrl__: /* switch between languages */
    if (!p_ari)
      goto normalchar;
    ins_ctrl_();
    break;
#endif

  case Ctrl_D: /* Make indent one shiftwidth smaller. */
               /* FALLTHROUGH */

  case Ctrl_T: /* Make indent one shiftwidth greater. */
    ins_shift(c, context->lastc);
    auto_format(FALSE, TRUE);
    context->inserted_space = FALSE;
    break;

  case K_DEL: /* delete character under the cursor */
  case K_KDEL:
    ins_del();
    auto_format(FALSE, TRUE);
    break;

  case K_BS: /* delete character before the cursor */
  case Ctrl_H:
    context->did_backspace =
        ins_bs(c, BACKSPACE_CHAR, &context->inserted_space);
    auto_format(FALSE, TRUE);
    break;

  case Ctrl_W: /* delete word before the cursor */
#ifdef FEAT_JOB_CHANNEL
    if (bt_prompt(curbuf) && (mod_mask & MOD_MASK_SHIFT) == 0)
    {
      // In a prompt window CTRL-W is used for window commands.
      // Use Shift-CTRL-W to delete a word.
      stuffcharReadbuff(Ctrl_W);
      restart_edit = 'A';
      context->nomove = TRUE;
      context->count = 0;
      goto doESCkey;
    }
#endif
    context->did_backspace =
        ins_bs(c, BACKSPACE_WORD, &context->inserted_space);
    auto_format(FALSE, TRUE);
    break;

  case Ctrl_U: /* delete all inserted text in current line */
    context->did_backspace =
        ins_bs(c, BACKSPACE_LINE, &context->inserted_space);
    auto_format(FALSE, TRUE);
    context->inserted_space = FALSE;
    break;

  case K_PS:
    bracketed_paste(PASTE_INSERT, FALSE, NULL);
    if (context->cmdchar == K_PS)
      /* invoked from normal mode, bail out */
      goto doESCkey;
    break;
  case K_PE:
    /* Got K_PE without K_PS, ignore. */
    break;

  case K_IGNORE: /* Something mapped to nothing */
    break;

  case K_CURSORHOLD: /* Didn't type something for a while. */
    ins_apply_autocmds(EVENT_CURSORHOLDI);
    did_cursorhold = TRUE;
    break;

  case K_HOME: /* <Home> */
  case K_KHOME:
  case K_S_HOME:
  case K_C_HOME:
    ins_home(c);
    break;

  case K_END: /* <End> */
  case K_KEND:
  case K_S_END:
  case K_C_END:
    ins_end(c);
    break;

  case K_LEFT: /* <Left> */
    if (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
      ins_s_left();
    else
      ins_left();
    break;

  case K_S_LEFT: /* <S-Left> */
  case K_C_LEFT:
    ins_s_left();
    break;

  case K_RIGHT: /* <Right> */
    if (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
      ins_s_right();
    else
      ins_right();
    break;

  case K_S_RIGHT: /* <S-Right> */
  case K_C_RIGHT:
    ins_s_right();
    break;

  case K_UP: /* <Up> */
    if (mod_mask & MOD_MASK_SHIFT)
      ins_pageup();
    else
      ins_up(FALSE);
    break;

  case K_S_UP: /* <S-Up> */
  case K_PAGEUP:
  case K_KPAGEUP:
    ins_pageup();
    break;

  case K_DOWN: /* <Down> */
    if (mod_mask & MOD_MASK_SHIFT)
      ins_pagedown();
    else
      ins_down(FALSE);
    break;

  case K_S_DOWN: /* <S-Down> */
  case K_PAGEDOWN:
  case K_KPAGEDOWN:
    ins_pagedown();
    break;
  case K_S_TAB: /* When not mapped, use like a normal TAB */
    c = TAB;
    /* FALLTHROUGH */

  case TAB: /* TAB or Complete patterns along path */
    context->inserted_space = FALSE;
    if (ins_tab())
      goto normalchar; /* insert TAB as a normal char */
    auto_format(FALSE, TRUE);
    break;

  case K_KENTER: /* <Enter> */
    c = CAR;
    /* FALLTHROUGH */
  case CAR:
  case NL:
#if defined(FEAT_QUICKFIX)
    /* In a quickfix window a <CR> jumps to the error under the
     * cursor. */
    if (bt_quickfix(curbuf) && c == CAR)
    {
      if (curwin->w_llist_ref == NULL) /* quickfix window */
        do_cmdline_cmd((char_u *)".cc");
      else /* location list window */
        do_cmdline_cmd((char_u *)".ll");
      break;
    }
#endif
#ifdef FEAT_JOB_CHANNEL
    if (bt_prompt(curbuf))
    {
      invoke_prompt_callback();
      if (!bt_prompt(curbuf))
        // buffer changed to a non-prompt buffer, get out of
        // Insert mode
        goto doESCkey;
      break;
    }
#endif
    if (ins_eol(c) == FAIL && !p_im)
      goto doESCkey; /* out of memory */
    auto_format(FALSE, FALSE);
    context->inserted_space = FALSE;
    break;

#if defined(FEAT_DIGRAPHS)
  case Ctrl_K: /* digraph or keyword completion */
    c = ins_digraph();
    if (c == NUL)
      break;
    goto normalchar;
#endif
  case Ctrl_L: /* Whole line completion after ^X */
  {
    /* CTRL-L with 'insertmode' set: Leave Insert mode */
    if (p_im)
    {
      if (echeck_abbr(Ctrl_L + ABBR_OFF))
        break;
      goto doESCkey;
    }
    goto normalchar;
  }
  case Ctrl_Y: /* copy from previous line or scroll down */
  case Ctrl_E: /* copy from next line	   or scroll up */
    c = ins_ctrl_ey(c);
    break;

  default:

  normalchar:
    /*
     * Insert a normal character.
     */
#if defined(FEAT_EVAL)
    if (!p_paste)
    {
      /* Trigger InsertCharPre. */
      char_u *str = do_insert_char_pre(c);
      char_u *p;

      if (str != NULL)
      {
        if (*str != NUL && stop_arrow() != FAIL)
        {
          /* Insert the new value of v:char literally. */
          for (p = str; *p != NUL; MB_PTR_ADV(p))
          {
            c = PTR2CHAR(p);
            if (c == CAR || c == K_KENTER || c == NL)
              ins_eol(c);
            else
              ins_char(c);
          }
          AppendToRedobuffLit(str, -1);
        }
        vim_free(str);
        c = NUL;
      }

      /* If the new value is already inserted or an empty string
       * then don't insert any character. */
      if (c == NUL)
        break;
    }
#endif
#ifdef FEAT_SMARTINDENT
    /* Try to perform smart-indenting. */
    ins_try_si(c);
#endif

    if (c == ' ')
    {
      context->inserted_space = TRUE;
      if (Insstart_blank_vcol == MAXCOL &&
          curwin->w_cursor.lnum == Insstart.lnum)
        Insstart_blank_vcol = get_nolist_virtcol();
    }

    /* Insert a normal character and check for abbreviations on a
     * special character.  Let CTRL-] expand abbreviations without
     * inserting it. */
    if (vim_iswordc(c) ||
        (!echeck_abbr(
             // Add ABBR_OFF for characters above 0x100, this is
             // what check_abbr() expects.
             (has_mbyte && c >= 0x100) ? (c + ABBR_OFF) : c) &&
         c != Ctrl_RSB))
    {
      insert_special(c, FALSE, FALSE);
#ifdef FEAT_RIGHTLEFT
      revins_legal++;
      revins_chars++;
#endif
    }

    auto_format(FALSE, TRUE);

#ifdef FEAT_FOLDING
    /* When inserting a character the cursor line must never be in a
     * closed fold. */
    foldOpenCursor();
#endif
    break;
  } /* end of switch (c) */

  /* If typed something may trigger CursorHoldI again. */
  if (c != K_CURSORHOLD
#ifdef FEAT_COMPL_FUNC
      /* but not in CTRL-X mode, a script can't restore the state */
      && ctrl_x_mode_normal()
#endif
  )
    did_cursorhold = FALSE;

  /* If the cursor was moved we didn't just insert a space */
  if (arrow_used)
    context->inserted_space = FALSE;

  return HANDLED;
};

/*
 * edit(): Start inserting text.
 *
 * "cmdchar" can be:
 * 'i'	normal insert command
 * 'a'	normal append command
 * K_PS bracketed paste
 * 'R'	replace command
 * 'r'	"r<CR>" command: insert one <CR>.  Note: count can be > 1, for redo,
 *	but still only one <CR> is inserted.  The <Esc> is not used for redo.
 * 'g'	"gI" command.
 * 'V'	"gR" command for Virtual Replace mode.
 * 'v'	"gr" command for single character Virtual Replace mode.
 *
 * This function is not called recursively.  For CTRL-O commands, it returns
 * and lets the caller handle the Normal-mode command.
 *
 * Return TRUE if a CTRL-O command caused the return (insert mode pending).
 */
int edit(int cmdchar, int startln, /* if set, insert at start of line */
         long count)
{
  int c = 0;
  char_u *ptr;
  int lastc = 0;
  int mincol;
  int i;
  int did_backspace = TRUE; /* previous char was backspace */
  linenr_T old_topline = 0; /* topline before insertion */
#ifdef FEAT_DIFF
  int old_topfill = -1;
#endif
  int inserted_space = FALSE; /* just inserted a space */
  int replaceState = REPLACE;
  int nomove = FALSE; /* don't move cursor on return */
#ifdef FEAT_JOB_CHANNEL
  int cmdchar_todo = cmdchar;
#endif

  /* Remember whether editing was restarted after CTRL-O. */
  did_restart_edit = restart_edit;

  /* sleep before redrawing, needed for "CTRL-O :" that results in an
   * error message */
  check_for_delay(TRUE);

  /* set Insstart_orig to Insstart */
  update_Insstart_orig = TRUE;

#ifdef HAVE_SANDBOX
  /* Don't allow inserting in the sandbox. */
  if (sandbox != 0)
  {
    emsg(_(e_sandbox));
    return FALSE;
  }
#endif
  /* Don't allow changes in the buffer while editing the cmdline.  The
   * caller of getcmdline() may get confused. */
  if (textlock != 0)
  {
    emsg(_(e_secure));
    return FALSE;
  }

  /*
   * Trigger InsertEnter autocommands.  Do not do this for "r<CR>" or "grx".
   */
  if (cmdchar != 'r' && cmdchar != 'v')
  {
    pos_T save_cursor = curwin->w_cursor;

#ifdef FEAT_EVAL
    if (cmdchar == 'R')
      ptr = (char_u *)"r";
    else if (cmdchar == 'V')
      ptr = (char_u *)"v";
    else
      ptr = (char_u *)"i";
    set_vim_var_string(VV_INSERTMODE, ptr, 1);
    set_vim_var_string(VV_CHAR, NULL, -1); /* clear v:char */
#endif
    ins_apply_autocmds(EVENT_INSERTENTER);

    /* Make sure the cursor didn't move.  Do call check_cursor_col() in
     * case the text was modified.  Since Insert mode was not started yet
     * a call to check_cursor_col() may move the cursor, especially with
     * the "A" command, thus set State to avoid that. Also check that the
     * line number is still valid (lines may have been deleted).
     * Do not restore if v:char was set to a non-empty string. */
    if (!EQUAL_POS(curwin->w_cursor, save_cursor)
#ifdef FEAT_EVAL
        && *get_vim_var_str(VV_CHAR) == NUL
#endif
        && save_cursor.lnum <= curbuf->b_ml.ml_line_count)
    {
      int save_state = State;

      curwin->w_cursor = save_cursor;
      State = INSERT;
      check_cursor_col();
      State = save_state;
    }
  }

  {
    Insstart = curwin->w_cursor;
    if (startln)
      Insstart.col = 0;
  }
  Insstart_textlen = (colnr_T)linetabsize(ml_get_curline());
  Insstart_blank_vcol = MAXCOL;
  if (!did_ai)
    ai_col = 0;

  if (cmdchar != NUL && restart_edit == 0)
  {
    ResetRedobuff();
    AppendNumberToRedobuff(count);
    if (cmdchar == 'V' || cmdchar == 'v')
    {
      /* "gR" or "gr" command */
      AppendCharToRedobuff('g');
      AppendCharToRedobuff((cmdchar == 'v') ? 'r' : 'R');
    }
    else
    {
      if (cmdchar == K_PS)
        AppendCharToRedobuff('a');
      else
        AppendCharToRedobuff(cmdchar);
      if (cmdchar == 'g') /* "gI" command */
        AppendCharToRedobuff('I');
      else if (cmdchar == 'r') /* "r<CR>" command */
        count = 1;             /* insert only one <CR> */
    }
  }

  if (cmdchar == 'R')
  {
    State = REPLACE;
  }
  else if (cmdchar == 'V' || cmdchar == 'v')
  {
    State = VREPLACE;
    replaceState = VREPLACE;
    orig_line_count = curbuf->b_ml.ml_line_count;
    vr_lines_changed = 1;
  }
  else
    State = INSERT;

  stop_insert_mode = FALSE;

  /*
   * Need to recompute the cursor position, it might move when the cursor is
   * on a TAB or special character.
   */
  curs_columns(TRUE);

  /*
   * Enable langmap or IME, indicated by 'iminsert'.
   * Note that IME may enabled/disabled without us noticing here, thus the
   * 'iminsert' value may not reflect what is actually used.  It is updated
   * when hitting <Esc>.
   */
  if (curbuf->b_p_iminsert == B_IMODE_LMAP)
    State |= LANGMAP;

#ifdef FEAT_RIGHTLEFT
  /* there is no reverse replace mode */
  revins_on = (State == INSERT && p_ri);
  if (revins_on)
    undisplay_dollar();
  revins_chars = 0;
  revins_legal = 0;
  revins_scol = -1;
#endif
  if (!p_ek)
    /* Disable bracketed paste mode, we won't recognize the escape
     * sequences. */
    out_str(T_BD);

  /*
   * Handle restarting Insert mode.
   * Don't do this for "CTRL-O ." (repeat an insert): In that case we get
   * here with something in the stuff buffer.
   */
  if (restart_edit != 0 && stuff_empty())
  {
    arrow_used = TRUE;
    restart_edit = 0;

    /*
     * If the cursor was after the end-of-line before the CTRL-O and it is
     * now at the end-of-line, put it after the end-of-line (this is not
     * correct in very rare cases).
     * Also do this if curswant is greater than the current virtual
     * column.  Eg after "^O$" or "^O80|".
     */
    validate_virtcol();
    update_curswant();
    if (((ins_at_eol && curwin->w_cursor.lnum == o_lnum) ||
         curwin->w_curswant > curwin->w_virtcol) &&
        *(ptr = ml_get_curline() + curwin->w_cursor.col) != NUL)
    {
      if (ptr[1] == NUL)
        ++curwin->w_cursor.col;
      else if (has_mbyte)
      {
        i = (*mb_ptr2len)(ptr);
        if (ptr[i] == NUL)
          curwin->w_cursor.col += i;
      }
    }
    ins_at_eol = FALSE;
  }
  else
    arrow_used = FALSE;

  /* we are in insert mode now, don't need to start it anymore */
  need_start_insertmode = FALSE;

  /* Need to save the line for undo before inserting the first char. */
  ins_need_undo = TRUE;

#ifdef FEAT_FOLDING
  /* The cursor line is not in a closed fold, unless 'insertmode' is set or
   * restarting. */
  if (!p_im && did_restart_edit == 0)
    foldOpenCursor();
#endif

  /*
   * If 'showmode' is set, show the current (insert/replace/..) mode.
   * A warning message for changing a readonly file is given here, before
   * actually changing anything.  It's put after the mode, if any.
   */
  i = 0;

  if (!p_im && did_restart_edit == 0)
    change_warning(i == 0 ? 0 : i + 1);

#ifdef FEAT_DIGRAPHS
  do_digraph(-1); /* clear digraphs */
#endif

  /*
   * Get the current length of the redo buffer, those characters have to be
   * skipped if we want to get to the inserted characters.
   */
  ptr = get_inserted();
  if (ptr == NULL)
    new_insert_skip = 0;
  else
  {
    new_insert_skip = (int)STRLEN(ptr);
    vim_free(ptr);
  }

  old_indent = 0;

  /*
   * Main loop in Insert mode: repeat until Insert mode is left.
   */
  for (;;)
  {
#ifdef FEAT_RIGHTLEFT
    if (!revins_legal)
      revins_scol = -1; /* reset on illegal motions */
    else
      revins_legal = 0;
#endif
    if (arrow_used) /* don't repeat insert when arrow key used */
      count = 0;

    if (update_Insstart_orig)
      Insstart_orig = Insstart;

    if (stop_insert_mode)
    {
      /* ":stopinsert" used or 'insertmode' reset */
      count = 0;
      goto doESCkey;
    }

    /* set curwin->w_curswant for next K_DOWN or K_UP */
    if (!arrow_used)
      curwin->w_set_curswant = TRUE;

    /* If there is no typeahead may check for timestamps (e.g., for when a
     * menu invoked a shell command). */
    if (stuff_empty())
    {
      did_check_timestamps = FALSE;
      if (need_check_timestamps)
        check_timestamps(FALSE);
    }

    /*
     * When emsg() was called msg_scroll will have been set.
     */
    msg_scroll = FALSE;

#ifdef FEAT_FOLDING
    /* Open fold at the cursor line, according to 'foldopen'. */
    if (fdo_flags & FDO_INSERT)
      foldOpenCursor();
    /* Close folds where the cursor isn't, according to 'foldclose' */
    if (!char_avail())
      foldCheckClose();
#endif

#ifdef FEAT_JOB_CHANNEL
    if (bt_prompt(curbuf))
    {
      init_prompt(cmdchar_todo);
      cmdchar_todo = NUL;
    }
#endif

    /*
     * If we inserted a character at the last position of the last line in
     * the window, scroll the window one line up. This avoids an extra
     * redraw.
     * This is detected when the cursor column is smaller after inserting
     * something.
     * Don't do this when the topline changed already, it has
     * already been adjusted (by insertchar() calling open_line())).
     */
    if (curbuf->b_mod_set && curwin->w_p_wrap && !did_backspace &&
        curwin->w_topline == old_topline
#ifdef FEAT_DIFF
        && curwin->w_topfill == old_topfill
#endif
    )
    {
      mincol = curwin->w_wcol;
      validate_cursor_col();

      if (
#ifdef FEAT_VARTABS
          (int)curwin->w_wcol < mincol - tabstop_at(get_nolist_virtcol(),
                                                    curbuf->b_p_ts,
                                                    curbuf->b_p_vts_array)
#else
          (int)curwin->w_wcol < mincol - curbuf->b_p_ts
#endif
          && curwin->w_wrow == W_WINROW(curwin) + curwin->w_height - 1 -
                                   get_scrolloff_value() &&
          (curwin->w_cursor.lnum != curwin->w_topline
#ifdef FEAT_DIFF
           || curwin->w_topfill > 0
#endif
           ))
      {
#ifdef FEAT_DIFF
        if (curwin->w_topfill > 0)
          --curwin->w_topfill;
        else
#endif
#ifdef FEAT_FOLDING
            if (hasFolding(curwin->w_topline, NULL, &old_topline))
          set_topline(curwin, old_topline + 1);
        else
#endif
          set_topline(curwin, curwin->w_topline + 1);
      }
    }

    /* May need to adjust w_topline to show the cursor. */
    update_topline();

    did_backspace = FALSE;

    validate_cursor(); /* may set must_redraw */

    /*
     * Redraw the display when no characters are waiting.
     * Also shows mode, ruler and positions cursor.
     */
    ins_redraw(TRUE);

    if (curwin->w_p_scb)
      do_check_scrollbind(TRUE);

    if (curwin->w_p_crb)
      do_check_cursorbind();
    update_curswant();
    old_topline = curwin->w_topline;
#ifdef FEAT_DIFF
    old_topfill = curwin->w_topfill;
#endif

    /*
     * Get a character for Insert mode.  Ignore K_IGNORE and K_NOP.
     */
    if (c != K_CURSORHOLD)
      lastc = c; /* remember the previous char for CTRL-D */

    /* After using CTRL-G U the next cursor key will not break undo. */
    if (dont_sync_undo == MAYBE)
      dont_sync_undo = TRUE;
    else
      dont_sync_undo = FALSE;
    if (cmdchar == K_PS)
      /* Got here from normal mode when bracketed paste started. */
      c = K_PS;
    else
      do
      {
        c = safe_vgetc();

        if (stop_insert_mode)
        {
          // Insert mode ended, possibly from a callback.
          count = 0;
          nomove = TRUE;
          goto doESCkey;
        }
      } while (c == K_IGNORE || c == K_NOP);

    /* Don't want K_CURSORHOLD for the second key, e.g., after CTRL-V. */
    did_cursorhold = TRUE;

#ifdef FEAT_RIGHTLEFT
    if (p_hkmap && KeyTyped)
      c = hkmap(c); /* Hebrew mode mapping */
#endif

    /* CTRL-\ CTRL-N goes to Normal mode,
     * CTRL-\ CTRL-G goes to mode selected with 'insertmode',
     * CTRL-\ CTRL-O is like CTRL-O but without moving the cursor.  */
    if (c == Ctrl_BSL)
    {
      /* may need to redraw when no more chars available now */
      ins_redraw(FALSE);
      ++no_mapping;
      ++allow_keys;
      c = plain_vgetc();
      --no_mapping;
      --allow_keys;
      if (c != Ctrl_N && c != Ctrl_G && c != Ctrl_O)
      {
        /* it's something else */
        vungetc(c);
        c = Ctrl_BSL;
      }
      else if (c == Ctrl_G && p_im)
        continue;
      else
      {
        if (c == Ctrl_O)
        {
          ins_ctrl_o();
          ins_at_eol = FALSE; /* cursor keeps its column */
          nomove = TRUE;
        }
        count = 0;
        goto doESCkey;
      }
    }

#ifdef FEAT_DIGRAPHS
    c = do_digraph(c);
#endif

    if (c == Ctrl_V || c == Ctrl_Q)
    {
      ins_ctrl_v();
      c = Ctrl_V; /* pretend CTRL-V is last typed character */
      continue;
    }

#ifdef FEAT_RIGHTLEFT
    if (curwin->w_p_rl)
      switch (c)
      {
      case K_LEFT:
        c = K_RIGHT;
        break;
      case K_S_LEFT:
        c = K_S_RIGHT;
        break;
      case K_C_LEFT:
        c = K_C_RIGHT;
        break;
      case K_RIGHT:
        c = K_LEFT;
        break;
      case K_S_RIGHT:
        c = K_S_LEFT;
        break;
      case K_C_RIGHT:
        c = K_C_LEFT;
        break;
      }
#endif

    /*
     * If 'keymodel' contains "startsel", may start selection.  If it
     * does, a CTRL-O and c will be stuffed, we need to get these
     * characters.
     */
    if (ins_start_select(c))
      continue;

    /*
     * The big switch to handle a character in insert mode.
     */
    switch (c)
    {
    case ESC: /* End input mode */
      if (echeck_abbr(ESC + ABBR_OFF))
        break;
      /* FALLTHROUGH */

    case Ctrl_C: /* End input mode */
#ifdef FEAT_JOB_CHANNEL
      if (c == Ctrl_C && bt_prompt(curbuf))
      {
        if (invoke_prompt_interrupt())
        {
          if (!bt_prompt(curbuf))
            // buffer changed to a non-prompt buffer, get out of
            // Insert mode
            goto doESCkey;
          break;
        }
      }
#endif

#ifdef UNIX
    do_intr:
#endif
      /* when 'insertmode' set, and not halfway a mapping, don't leave
       * Insert mode */
      if (goto_im())
      {
        if (got_int)
        {
          (void)vgetc(); /* flush all buffers */
          got_int = FALSE;
        }
        else
          vim_beep(BO_IM);
        break;
      }
    doESCkey:
      /*
       * This is the ONLY return from edit()!
       */
      /* Always update o_lnum, so that a "CTRL-O ." that adds a line
       * still puts the cursor back after the inserted text. */
      if (ins_at_eol && gchar_cursor() == NUL)
        o_lnum = curwin->w_cursor.lnum;

      if (ins_esc(&count, cmdchar, nomove))
      {
        // When CTRL-C was typed got_int will be set, with the result
        // that the autocommands won't be executed. When mapped got_int
        // is not set, but let's keep the behavior the same.
        if (cmdchar != 'r' && cmdchar != 'v' && c != Ctrl_C)
          ins_apply_autocmds(EVENT_INSERTLEAVE);
        did_cursorhold = FALSE;
        return (c == Ctrl_O);
      }
      continue;

    case Ctrl_Z: /* suspend when 'insertmode' set */
      if (!p_im)
        goto normalchar; /* insert CTRL-Z as normal char */
      do_cmdline_cmd((char_u *)"stop");
      continue;

    case Ctrl_O: /* execute one command */
#ifdef FEAT_COMPL_FUNC
      if (ctrl_x_mode_omni())
        goto docomplete;
#endif
      if (echeck_abbr(Ctrl_O + ABBR_OFF))
        break;
      ins_ctrl_o();

      /* don't move the cursor left when 'virtualedit' has "onemore". */
      if (ve_flags & VE_ONEMORE)
      {
        ins_at_eol = FALSE;
        nomove = TRUE;
      }
      count = 0;
      goto doESCkey;

    case K_INS: /* toggle insert/replace mode */
    case K_KINS:
      ins_insert(replaceState);
      break;

    case K_SELECT: /* end of Select mode mapping - ignore */
      break;

    case K_HELP: /* Help key works like <ESC> <Help> */
    case K_F1:
    case K_XF1:
      stuffcharReadbuff(K_HELP);
      if (p_im)
        need_start_insertmode = TRUE;
      goto doESCkey;

    case K_ZERO: /* Insert the previously inserted text. */
    case NUL:
    case Ctrl_A:
      /* For ^@ the trailing ESC will end the insert, unless there is an
       * error.  */
      if (stuff_inserted(NUL, 1L, (c == Ctrl_A)) == FAIL && c != Ctrl_A &&
          !p_im)
        goto doESCkey; /* quit insert mode */
      inserted_space = FALSE;
      break;

    case Ctrl_G: /* commands starting with CTRL-G */
      ins_ctrl_g();
      break;

    case Ctrl_HAT: /* switch input mode and/or langmap */
      ins_ctrl_hat();
      break;

#ifdef FEAT_RIGHTLEFT
    case Ctrl__: /* switch between languages */
      if (!p_ari)
        goto normalchar;
      ins_ctrl_();
      break;
#endif

    case Ctrl_D: /* Make indent one shiftwidth smaller. */
      /* FALLTHROUGH */

    case Ctrl_T: /* Make indent one shiftwidth greater. */
      ins_shift(c, lastc);
      auto_format(FALSE, TRUE);
      inserted_space = FALSE;
      break;

    case K_DEL: /* delete character under the cursor */
    case K_KDEL:
      ins_del();
      auto_format(FALSE, TRUE);
      break;

    case K_BS: /* delete character before the cursor */
    case Ctrl_H:
      did_backspace = ins_bs(c, BACKSPACE_CHAR, &inserted_space);
      auto_format(FALSE, TRUE);
      break;

    case Ctrl_W: /* delete word before the cursor */
#ifdef FEAT_JOB_CHANNEL
      if (bt_prompt(curbuf) && (mod_mask & MOD_MASK_SHIFT) == 0)
      {
        // In a prompt window CTRL-W is used for window commands.
        // Use Shift-CTRL-W to delete a word.
        stuffcharReadbuff(Ctrl_W);
        restart_edit = 'A';
        nomove = TRUE;
        count = 0;
        goto doESCkey;
      }
#endif
      did_backspace = ins_bs(c, BACKSPACE_WORD, &inserted_space);
      auto_format(FALSE, TRUE);
      break;

    case Ctrl_U: /* delete all inserted text in current line */
#ifdef FEAT_COMPL_FUNC
      /* CTRL-X CTRL-U completes with 'completefunc'. */
      if (ctrl_x_mode_function())
        goto docomplete;
#endif
      did_backspace = ins_bs(c, BACKSPACE_LINE, &inserted_space);
      auto_format(FALSE, TRUE);
      inserted_space = FALSE;
      break;

    case K_PS:
      bracketed_paste(PASTE_INSERT, FALSE, NULL);
      if (cmdchar == K_PS)
        /* invoked from normal mode, bail out */
        goto doESCkey;
      break;
    case K_PE:
      /* Got K_PE without K_PS, ignore. */
      break;

    case K_IGNORE: /* Something mapped to nothing */
      break;

    case K_CURSORHOLD: /* Didn't type something for a while. */
      ins_apply_autocmds(EVENT_CURSORHOLDI);
      did_cursorhold = TRUE;
      break;

    case K_HOME: /* <Home> */
    case K_KHOME:
    case K_S_HOME:
    case K_C_HOME:
      ins_home(c);
      break;

    case K_END: /* <End> */
    case K_KEND:
    case K_S_END:
    case K_C_END:
      ins_end(c);
      break;

    case K_LEFT: /* <Left> */
      if (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
        ins_s_left();
      else
        ins_left();
      break;

    case K_S_LEFT: /* <S-Left> */
    case K_C_LEFT:
      ins_s_left();
      break;

    case K_RIGHT: /* <Right> */
      if (mod_mask & (MOD_MASK_SHIFT | MOD_MASK_CTRL))
        ins_s_right();
      else
        ins_right();
      break;

    case K_S_RIGHT: /* <S-Right> */
    case K_C_RIGHT:
      ins_s_right();
      break;

    case K_UP: /* <Up> */
      if (mod_mask & MOD_MASK_SHIFT)
        ins_pageup();
      else
        ins_up(FALSE);
      break;

    case K_S_UP: /* <S-Up> */
    case K_PAGEUP:
    case K_KPAGEUP:
      ins_pageup();
      break;

    case K_DOWN: /* <Down> */
      if (mod_mask & MOD_MASK_SHIFT)
        ins_pagedown();
      else
        ins_down(FALSE);
      break;

    case K_S_DOWN: /* <S-Down> */
    case K_PAGEDOWN:
    case K_KPAGEDOWN:
      ins_pagedown();
      break;

    case K_S_TAB: /* When not mapped, use like a normal TAB */
      c = TAB;
      /* FALLTHROUGH */

    case TAB: /* TAB or Complete patterns along path */
      inserted_space = FALSE;
      if (ins_tab())
        goto normalchar; /* insert TAB as a normal char */
      auto_format(FALSE, TRUE);
      break;

    case K_KENTER: /* <Enter> */
      c = CAR;
      /* FALLTHROUGH */
    case CAR:
    case NL:
#if defined(FEAT_QUICKFIX)
      /* In a quickfix window a <CR> jumps to the error under the
       * cursor. */
      if (bt_quickfix(curbuf) && c == CAR)
      {
        if (curwin->w_llist_ref == NULL) /* quickfix window */
          do_cmdline_cmd((char_u *)".cc");
        else /* location list window */
          do_cmdline_cmd((char_u *)".ll");
        break;
      }
#endif
#ifdef FEAT_JOB_CHANNEL
      if (bt_prompt(curbuf))
      {
        invoke_prompt_callback();
        if (!bt_prompt(curbuf))
          // buffer changed to a non-prompt buffer, get out of
          // Insert mode
          goto doESCkey;
        break;
      }
#endif
      if (ins_eol(c) == FAIL && !p_im)
        goto doESCkey; /* out of memory */
      auto_format(FALSE, FALSE);
      inserted_space = FALSE;
      break;

#if defined(FEAT_DIGRAPHS)
    case Ctrl_K: /* digraph or keyword completion */
#ifdef FEAT_DIGRAPHS
      c = ins_digraph();
      if (c == NUL)
        break;
#endif
      goto normalchar;
#endif

    case Ctrl_L: /* Whole line completion after ^X */
    {
      /* CTRL-L with 'insertmode' set: Leave Insert mode */
      if (p_im)
      {
        if (echeck_abbr(Ctrl_L + ABBR_OFF))
          break;
        goto doESCkey;
      }
      goto normalchar;
    }
    case Ctrl_Y: /* copy from previous line or scroll down */
    case Ctrl_E: /* copy from next line	   or scroll up */
      c = ins_ctrl_ey(c);
      break;

    default:
#ifdef UNIX
      if (c == intr_char) /* special interrupt char */
        goto do_intr;
#endif

    normalchar:
      /*
       * Insert a normal character.
       */
#if defined(FEAT_EVAL)
      if (!p_paste)
      {
        /* Trigger InsertCharPre. */
        char_u *str = do_insert_char_pre(c);
        char_u *p;

        if (str != NULL)
        {
          if (*str != NUL && stop_arrow() != FAIL)
          {
            /* Insert the new value of v:char literally. */
            for (p = str; *p != NUL; MB_PTR_ADV(p))
            {
              c = PTR2CHAR(p);
              if (c == CAR || c == K_KENTER || c == NL)
                ins_eol(c);
              else
                ins_char(c);
            }
            AppendToRedobuffLit(str, -1);
          }
          vim_free(str);
          c = NUL;
        }

        /* If the new value is already inserted or an empty string
         * then don't insert any character. */
        if (c == NUL)
          break;
      }
#endif
#ifdef FEAT_SMARTINDENT
      /* Try to perform smart-indenting. */
      ins_try_si(c);
#endif

      if (c == ' ')
      {
        inserted_space = TRUE;
        if (Insstart_blank_vcol == MAXCOL &&
            curwin->w_cursor.lnum == Insstart.lnum)
          Insstart_blank_vcol = get_nolist_virtcol();
      }

      /* Insert a normal character and check for abbreviations on a
       * special character.  Let CTRL-] expand abbreviations without
       * inserting it. */
      if (vim_iswordc(c) ||
          (!echeck_abbr(
               // Add ABBR_OFF for characters above 0x100, this is
               // what check_abbr() expects.
               (has_mbyte && c >= 0x100) ? (c + ABBR_OFF) : c) &&
           c != Ctrl_RSB))
      {
        insert_special(c, FALSE, FALSE);
#ifdef FEAT_RIGHTLEFT
        revins_legal++;
        revins_chars++;
#endif
      }

      auto_format(FALSE, TRUE);

#ifdef FEAT_FOLDING
      /* When inserting a character the cursor line must never be in a
       * closed fold. */
      foldOpenCursor();
#endif
      break;
    } /* end of switch (c) */

    /* If typed something may trigger CursorHoldI again. */
    if (c != K_CURSORHOLD)
      did_cursorhold = FALSE;

    /* If the cursor was moved we didn't just insert a space */
    if (arrow_used)
      inserted_space = FALSE;

  } /* for (;;) */
    /* NOTREACHED */
}

int ins_need_undo_get(void) { return ins_need_undo; }

/*
 * Redraw for Insert mode.
 * This is postponed until getting the next character to make '$' in the 'cpo'
 * option work correctly.
 * Only redraw when there are no characters available.  This speeds up
 * inserting sequences of characters (e.g., for CTRL-R).
 */
void ins_redraw(int ready) // not busy with something
{

  if (char_avail())
    return;

  /* Trigger CursorMoved if the cursor moved.  Not when the popup menu is
   * visible, the command might delete it. */
  if (ready &&
      (has_cursormovedI()) &&
      !EQUAL_POS(last_cursormoved, curwin->w_cursor))
  {
    if (has_cursormovedI())
    {
      /* Make sure curswant is correct, an autocommand may call
       * getcurpos(). */
      update_curswant();
      ins_apply_autocmds(EVENT_CURSORMOVEDI);
    }
    last_cursormoved = curwin->w_cursor;
  }

  /* Trigger TextChangedI if b_changedtick differs. */
  if (ready && has_textchangedI() &&
      curbuf->b_last_changedtick != CHANGEDTICK(curbuf))
  {
    aco_save_T aco;
    varnumber_T tick = CHANGEDTICK(curbuf);

    // save and restore curwin and curbuf, in case the autocmd changes them
    aucmd_prepbuf(&aco, curbuf);
    apply_autocmds(EVENT_TEXTCHANGEDI, NULL, NULL, FALSE, curbuf);
    aucmd_restbuf(&aco);
    curbuf->b_last_changedtick = CHANGEDTICK(curbuf);
    if (tick != CHANGEDTICK(curbuf)) // see ins_apply_autocmds()
      u_save(curwin->w_cursor.lnum, (linenr_T)(curwin->w_cursor.lnum + 1));
  }

  if (must_redraw)
    update_screen(0);

  showruler(FALSE);
  setcursor();
  emsg_on_display = FALSE; /* may remove error message now */
}

/*
 * Handle a CTRL-V or CTRL-Q typed in Insert mode.
 */
static void ins_ctrl_v(void)
{
  int c;
  int did_putchar = FALSE;

  /* may need to redraw when no more chars available now */
  ins_redraw(FALSE);

  if (redrawing() && !char_avail())
  {
    edit_putchar('^', TRUE);
    did_putchar = TRUE;
  }
  AppendToRedobuff((char_u *)CTRL_V_STR); /* CTRL-V */

  c = get_literal();
  if (did_putchar)
  {
    /* when the line fits in 'columns' the '^' is at the start of the next
     * line and will not removed by the redraw */
    edit_unputchar();
  }

  insert_special(c, FALSE, TRUE);
#ifdef FEAT_RIGHTLEFT
  revins_chars++;
  revins_legal++;
#endif
}

/*
 * Put a character directly onto the screen.  It's not stored in a buffer.
 * Used while handling CTRL-K, CTRL-V, etc. in Insert mode.
 */
static int pc_status;
#define PC_STATUS_UNSET 0                /* pc_bytes was not set */
#define PC_STATUS_RIGHT 1                /* right halve of double-wide char */
#define PC_STATUS_LEFT 2                 /* left halve of double-wide char */
#define PC_STATUS_SET 3                  /* pc_bytes was filled */
static char_u pc_bytes[MB_MAXBYTES + 1]; /* saved bytes */
static int pc_attr;
static int pc_row;
static int pc_col;

void edit_putchar(int c, int highlight)
{
  int attr;

  if (ScreenLines != NULL)
  {
    update_topline(); /* just in case w_topline isn't valid */
    validate_cursor();
    if (highlight)
      attr = HL_ATTR(HLF_8);
    else
      attr = 0;
    pc_row = W_WINROW(curwin) + curwin->w_wrow;
    pc_col = curwin->w_wincol;
    pc_status = PC_STATUS_UNSET;
#ifdef FEAT_RIGHTLEFT
    if (curwin->w_p_rl)
    {
      pc_col += curwin->w_width - 1 - curwin->w_wcol;
      if (has_mbyte)
      {
        int fix_col = mb_fix_col(pc_col, pc_row);

        if (fix_col != pc_col)
        {
          screen_putchar(' ', pc_row, fix_col, attr);
          --curwin->w_wcol;
          pc_status = PC_STATUS_RIGHT;
        }
      }
    }
    else
#endif
    {
      pc_col += curwin->w_wcol;
      if (mb_lefthalve(pc_row, pc_col))
        pc_status = PC_STATUS_LEFT;
    }

    /* save the character to be able to put it back */
    if (pc_status == PC_STATUS_UNSET)
    {
      screen_getbytes(pc_row, pc_col, pc_bytes, &pc_attr);
      pc_status = PC_STATUS_SET;
    }
    screen_putchar(c, pc_row, pc_col, attr);
  }
}

#if defined(FEAT_JOB_CHANNEL) || defined(PROTO)
/*
 * Return the effective prompt for the current buffer.
 */
char_u *prompt_text(void)
{
  if (curbuf->b_prompt_text == NULL)
    return (char_u *)"% ";
  return curbuf->b_prompt_text;
}

/*
 * Prepare for prompt mode: Make sure the last line has the prompt text.
 * Move the cursor to this line.
 */
static void init_prompt(int cmdchar_todo)
{
  char_u *prompt = prompt_text();
  char_u *text;

  curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
  text = ml_get_curline();
  if (STRNCMP(text, prompt, STRLEN(prompt)) != 0)
  {
    // prompt is missing, insert it or append a line with it
    if (*text == NUL)
      ml_replace(curbuf->b_ml.ml_line_count, prompt, TRUE);
    else
      ml_append(curbuf->b_ml.ml_line_count, prompt, 0, FALSE);
    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
    coladvance((colnr_T)MAXCOL);
    changed_bytes(curbuf->b_ml.ml_line_count, 0);
  }

  // Insert always starts after the prompt, allow editing text after it.
  if (Insstart_orig.lnum != curwin->w_cursor.lnum ||
      Insstart_orig.col != (int)STRLEN(prompt))
  {
    Insstart.lnum = curwin->w_cursor.lnum;
    Insstart.col = (int)STRLEN(prompt);
    Insstart_orig = Insstart;
    Insstart_textlen = Insstart.col;
    Insstart_blank_vcol = MAXCOL;
    arrow_used = FALSE;
  }

  if (cmdchar_todo == 'A')
    coladvance((colnr_T)MAXCOL);
  if (cmdchar_todo == 'I' || curwin->w_cursor.col <= (int)STRLEN(prompt))
    curwin->w_cursor.col = (int)STRLEN(prompt);
  /* Make sure the cursor is in a valid position. */
  check_cursor();
}

/*
 * Return TRUE if the cursor is in the editable position of the prompt line.
 */
int prompt_curpos_editable()
{
  return curwin->w_cursor.lnum == curbuf->b_ml.ml_line_count &&
         curwin->w_cursor.col >= (int)STRLEN(prompt_text());
}
#endif

/*
 * Undo the previous edit_putchar().
 */
void edit_unputchar(void)
{
  if (pc_status != PC_STATUS_UNSET && pc_row >= msg_scrolled)
  {
    if (pc_status == PC_STATUS_RIGHT)
      ++curwin->w_wcol;
    if (pc_status == PC_STATUS_RIGHT || pc_status == PC_STATUS_LEFT)
      redrawWinline(curwin, curwin->w_cursor.lnum);
    else
      screen_puts(pc_bytes, pc_row - msg_scrolled, pc_col, pc_attr);
  }
}

/*
 * Called when p_dollar is set: display a '$' at the end of the changed text
 * Only works when cursor is in the line that changes.
 */
void display_dollar(colnr_T col)
{
  colnr_T save_col;

  if (!redrawing())
    return;

  cursor_off();
  save_col = curwin->w_cursor.col;
  curwin->w_cursor.col = col;
  if (has_mbyte)
  {
    char_u *p;

    /* If on the last byte of a multi-byte move to the first byte. */
    p = ml_get_curline();
    curwin->w_cursor.col -= (*mb_head_off)(p, p + col);
  }
  curs_columns(FALSE); /* recompute w_wrow and w_wcol */
  if (curwin->w_wcol < curwin->w_width)
  {
    edit_putchar('$', FALSE);
    dollar_vcol = curwin->w_virtcol;
  }
  curwin->w_cursor.col = save_col;
}

/*
 * Call this function before moving the cursor from the normal insert position
 * in insert mode.
 */
static void undisplay_dollar(void)
{
  if (dollar_vcol >= 0)
  {
    dollar_vcol = -1;
    redrawWinline(curwin, curwin->w_cursor.lnum);
  }
}

/*
 * Insert an indent (for <Tab> or CTRL-T) or delete an indent (for CTRL-D).
 * Keep the cursor on the same character.
 * type == INDENT_INC	increase indent (for CTRL-T or <Tab>)
 * type == INDENT_DEC	decrease indent (for CTRL-D)
 * type == INDENT_SET	set indent to "amount"
 * if round is TRUE, round the indent to 'shiftwidth' (only with _INC and _Dec).
 */
void change_indent(int type, int amount, int round,
                   int replaced,           /* replaced character, put on replace stack */
                   int call_changed_bytes) /* call changed_bytes() */
{
  int vcol;
  int last_vcol;
  int insstart_less; /* reduction for Insstart.col */
  int new_cursor_col;
  int i;
  char_u *ptr;
  int save_p_list;
  int start_col;
  colnr_T vc;
  colnr_T orig_col = 0;                /* init for GCC */
  char_u *new_line, *orig_line = NULL; /* init for GCC */

  /* VREPLACE mode needs to know what the line was like before changing */
  if (State & VREPLACE_FLAG)
  {
    orig_line = vim_strsave(ml_get_curline()); /* Deal with NULL below */
    orig_col = curwin->w_cursor.col;
  }

  /* for the following tricks we don't want list mode */
  save_p_list = curwin->w_p_list;
  curwin->w_p_list = FALSE;
  vc = getvcol_nolist(&curwin->w_cursor);
  vcol = vc;

  /*
   * For Replace mode we need to fix the replace stack later, which is only
   * possible when the cursor is in the indent.  Remember the number of
   * characters before the cursor if it's possible.
   */
  start_col = curwin->w_cursor.col;

  /* determine offset from first non-blank */
  new_cursor_col = curwin->w_cursor.col;
  beginline(BL_WHITE);
  new_cursor_col -= curwin->w_cursor.col;

  insstart_less = curwin->w_cursor.col;

  /*
   * If the cursor is in the indent, compute how many screen columns the
   * cursor is to the left of the first non-blank.
   */
  if (new_cursor_col < 0)
    vcol = get_indent() - vcol;

  if (new_cursor_col > 0) /* can't fix replace stack */
    start_col = -1;

  /*
   * Set the new indent.  The cursor will be put on the first non-blank.
   */
  if (type == INDENT_SET)
    (void)set_indent(amount, call_changed_bytes ? SIN_CHANGED : 0);
  else
  {
    int save_State = State;

    /* Avoid being called recursively. */
    if (State & VREPLACE_FLAG)
      State = INSERT;
    shift_line(type == INDENT_DEC, round, 1, call_changed_bytes);
    State = save_State;
  }
  insstart_less -= curwin->w_cursor.col;

  /*
   * Try to put cursor on same character.
   * If the cursor is at or after the first non-blank in the line,
   * compute the cursor column relative to the column of the first
   * non-blank character.
   * If we are not in insert mode, leave the cursor on the first non-blank.
   * If the cursor is before the first non-blank, position it relative
   * to the first non-blank, counted in screen columns.
   */
  if (new_cursor_col >= 0)
  {
    /*
     * When changing the indent while the cursor is touching it, reset
     * Insstart_col to 0.
     */
    if (new_cursor_col == 0)
      insstart_less = MAXCOL;
    new_cursor_col += curwin->w_cursor.col;
  }
  else if (!(State & INSERT))
    new_cursor_col = curwin->w_cursor.col;
  else
  {
    /*
     * Compute the screen column where the cursor should be.
     */
    vcol = get_indent() - vcol;
    curwin->w_virtcol = (colnr_T)((vcol < 0) ? 0 : vcol);

    /*
     * Advance the cursor until we reach the right screen column.
     */
    vcol = last_vcol = 0;
    new_cursor_col = -1;
    ptr = ml_get_curline();
    while (vcol <= (int)curwin->w_virtcol)
    {
      last_vcol = vcol;
      if (has_mbyte && new_cursor_col >= 0)
        new_cursor_col += (*mb_ptr2len)(ptr + new_cursor_col);
      else
        ++new_cursor_col;
      vcol += lbr_chartabsize(ptr, ptr + new_cursor_col, (colnr_T)vcol);
    }
    vcol = last_vcol;

    /*
     * May need to insert spaces to be able to position the cursor on
     * the right screen column.
     */
    if (vcol != (int)curwin->w_virtcol)
    {
      curwin->w_cursor.col = (colnr_T)new_cursor_col;
      i = (int)curwin->w_virtcol - vcol;
      ptr = alloc(i + 1);
      if (ptr != NULL)
      {
        new_cursor_col += i;
        ptr[i] = NUL;
        while (--i >= 0)
          ptr[i] = ' ';
        ins_str(ptr);
        vim_free(ptr);
      }
    }

    /*
     * When changing the indent while the cursor is in it, reset
     * Insstart_col to 0.
     */
    insstart_less = MAXCOL;
  }

  curwin->w_p_list = save_p_list;

  if (new_cursor_col <= 0)
    curwin->w_cursor.col = 0;
  else
    curwin->w_cursor.col = (colnr_T)new_cursor_col;
  curwin->w_set_curswant = TRUE;
  changed_cline_bef_curs();

  /*
   * May have to adjust the start of the insert.
   */
  if (State & INSERT)
  {
    if (curwin->w_cursor.lnum == Insstart.lnum && Insstart.col != 0)
    {
      if ((int)Insstart.col <= insstart_less)
        Insstart.col = 0;
      else
        Insstart.col -= insstart_less;
    }
    if ((int)ai_col <= insstart_less)
      ai_col = 0;
    else
      ai_col -= insstart_less;
  }

  /*
   * For REPLACE mode, may have to fix the replace stack, if it's possible.
   * If the number of characters before the cursor decreased, need to pop a
   * few characters from the replace stack.
   * If the number of characters before the cursor increased, need to push a
   * few NULs onto the replace stack.
   */
  if (REPLACE_NORMAL(State) && start_col >= 0)
  {
    while (start_col > (int)curwin->w_cursor.col)
    {
      replace_join(0); /* remove a NUL from the replace stack */
      --start_col;
    }
    while (start_col < (int)curwin->w_cursor.col || replaced)
    {
      replace_push(NUL);
      if (replaced)
      {
        replace_push(replaced);
        replaced = NUL;
      }
      ++start_col;
    }
  }

  /*
   * For VREPLACE mode, we also have to fix the replace stack.  In this case
   * it is always possible because we backspace over the whole line and then
   * put it back again the way we wanted it.
   */
  if (State & VREPLACE_FLAG)
  {
    /* If orig_line didn't allocate, just return.  At least we did the job,
     * even if you can't backspace. */
    if (orig_line == NULL)
      return;

    /* Save new line */
    new_line = vim_strsave(ml_get_curline());
    if (new_line == NULL)
      return;

    /* We only put back the new line up to the cursor */
    new_line[curwin->w_cursor.col] = NUL;

    /* Put back original line */
    ml_replace(curwin->w_cursor.lnum, orig_line, FALSE);
    curwin->w_cursor.col = orig_col;

    /* Backspace from cursor to start of line */
    backspace_until_column(0);

    /* Insert new stuff into line again */
    ins_bytes(new_line);

    vim_free(new_line);
  }
}

/*
 * Truncate the space at the end of a line.  This is to be used only in an
 * insert mode.  It handles fixing the replace stack for REPLACE and VREPLACE
 * modes.
 */
void truncate_spaces(char_u *line)
{
  int i;

  /* find start of trailing white space */
  for (i = (int)STRLEN(line) - 1; i >= 0 && VIM_ISWHITE(line[i]); i--)
  {
    if (State & REPLACE_FLAG)
      replace_join(0); /* remove a NUL from the replace stack */
  }
  line[i + 1] = NUL;
}

/*
 * Backspace the cursor until the given column.  Handles REPLACE and VREPLACE
 * modes correctly.  May also be used when not in insert mode at all.
 * Will attempt not to go before "col" even when there is a composing
 * character.
 */
void backspace_until_column(int col)
{
  while ((int)curwin->w_cursor.col > col)
  {
    curwin->w_cursor.col--;
    if (State & REPLACE_FLAG)
      replace_do_bs(col);
    else if (!del_char_after_col(col))
      break;
  }
}

/*
 * Like del_char(), but make sure not to go before column "limit_col".
 * Only matters when there are composing characters.
 * Return TRUE when something was deleted.
 */
static int del_char_after_col(int limit_col UNUSED)
{
  if (enc_utf8 && limit_col >= 0)
  {
    colnr_T ecol = curwin->w_cursor.col + 1;

    /* Make sure the cursor is at the start of a character, but
     * skip forward again when going too far back because of a
     * composing character. */
    mb_adjust_cursor();
    while (curwin->w_cursor.col < (colnr_T)limit_col)
    {
      int l = utf_ptr2len(ml_get_cursor());

      if (l == 0) /* end of line */
        break;
      curwin->w_cursor.col += l;
    }
    if (*ml_get_cursor() == NUL || curwin->w_cursor.col == ecol)
      return FALSE;
    del_bytes((long)((int)ecol - curwin->w_cursor.col), FALSE, TRUE);
  }
  else
    (void)del_char(FALSE);
  return TRUE;
}

/*
 * Next character is interpreted literally.
 * A one, two or three digit decimal number is interpreted as its byte value.
 * If one or two digits are entered, the next character is given to vungetc().
 * For Unicode a character > 255 may be returned.
 */
int get_literal(void)
{
  int cc;
  int nc;
  int i;
  int hex = FALSE;
  int octal = FALSE;
  int unicode = 0;

  if (got_int)
    return Ctrl_C;

  ++no_mapping; /* don't map the next key hits */
  cc = 0;
  i = 0;
  for (;;)
  {
    nc = plain_vgetc();
    if (nc == 'x' || nc == 'X')
      hex = TRUE;
    else if (nc == 'o' || nc == 'O')
      octal = TRUE;
    else if (nc == 'u' || nc == 'U')
      unicode = nc;
    else
    {
      if (hex || unicode != 0)
      {
        if (!vim_isxdigit(nc))
          break;
        cc = cc * 16 + hex2nr(nc);
      }
      else if (octal)
      {
        if (nc < '0' || nc > '7')
          break;
        cc = cc * 8 + nc - '0';
      }
      else
      {
        if (!VIM_ISDIGIT(nc))
          break;
        cc = cc * 10 + nc - '0';
      }

      ++i;
    }

    if (cc > 255 && unicode == 0)
      cc = 255; /* limit range to 0-255 */
    nc = 0;

    if (hex) /* hex: up to two chars */
    {
      if (i >= 2)
        break;
    }
    else if (unicode) /* Unicode: up to four or eight chars */
    {
      if ((unicode == 'u' && i >= 4) || (unicode == 'U' && i >= 8))
        break;
    }
    else if (i >= 3) /* decimal or octal: up to three chars */
      break;
  }
  if (i == 0) /* no number entered */
  {
    if (nc == K_ZERO) /* NUL is stored as NL */
    {
      cc = '\n';
      nc = 0;
    }
    else
    {
      cc = nc;
      nc = 0;
    }
  }

  if (cc == 0) /* NUL is stored as NL */
    cc = '\n';
  if (enc_dbcs && (cc & 0xff) == 0)
    cc = '?'; /* don't accept an illegal DBCS char, the NUL in the
                 second byte will cause trouble! */

  --no_mapping;
  if (nc)
    vungetc(nc);
  got_int = FALSE; /* CTRL-C typed after CTRL-V is not an interrupt */
  return cc;
}

/*
 * Insert character, taking care of special keys and mod_mask
 */
static void insert_special(int c, int allow_modmask,
                           int ctrlv) /* c was typed after CTRL-V */
{
  char_u *p;
  int len;

  /*
   * Special function key, translate into "<Key>". Up to the last '>' is
   * inserted with ins_str(), so as not to replace characters in replace
   * mode.
   * Only use mod_mask for special keys, to avoid things like <S-Space>,
   * unless 'allow_modmask' is TRUE.
   */
  /* Command-key never produces a normal key */
  if (mod_mask & MOD_MASK_CMD)
  {
    allow_modmask = TRUE;
  }
  else
  {
    if (IS_SPECIAL(c) || (mod_mask && allow_modmask))
    {
      p = get_special_key_name(c, mod_mask);
      len = (int)STRLEN(p);
      c = p[len - 1];
      if (len > 2)
      {
        if (stop_arrow() == FAIL)
          return;
        p[len - 1] = NUL;
        ins_str(p);
        AppendToRedobuffLit(p, -1);
        ctrlv = FALSE;
      }
    }
    if (stop_arrow() == OK)
      insertchar(c, ctrlv ? INSCHAR_CTRLV : 0, -1);
  }
}

/*
 * Special characters in this context are those that need processing other
 * than the simple insertion that can be performed here. This includes ESC
 * which terminates the insert, and CR/NL which need special processing to
 * open up a new line. This routine tries to optimize insertions performed by
 * the "redo", "undo" or "put" commands, so it needs to know when it should
 * stop and defer processing to the "normal" mechanism.
 * '0' and '^' are special, because they can be followed by CTRL-D.
 */
#ifdef EBCDIC
#define ISSPECIAL(c) ((c) < ' ' || (c) == '0' || (c) == '^')
#else
#define ISSPECIAL(c) ((c) < ' ' || (c) >= DEL || (c) == '0' || (c) == '^')
#endif

#define WHITECHAR(cc) \
  (VIM_ISWHITE(cc) && \
   (!enc_utf8 || !utf_iscomposing(utf_ptr2char(ml_get_cursor() + 1))))

/*
 * "flags": INSCHAR_FORMAT - force formatting
 *	    INSCHAR_CTRLV  - char typed just after CTRL-V
 *	    INSCHAR_NO_FEX - don't use 'formatexpr'
 *
 *   NOTE: passes the flags value straight through to internal_format() which,
 *	   beside INSCHAR_FORMAT (above), is also looking for these:
 *	    INSCHAR_DO_COM   - format comments
 *	    INSCHAR_COM_LIST - format comments with num list or 2nd line indent
 */
void insertchar(int c,             /* character to insert or NUL */
                int flags,         /* INSCHAR_FORMAT, etc. */
                int second_indent) /* indent for second line if >= 0 */
{
  int textwidth;
#ifdef FEAT_COMMENTS
  char_u *p;
#endif
  int fo_ins_blank;
  int force_format = flags & INSCHAR_FORMAT;

  textwidth = comp_textwidth(force_format);
  fo_ins_blank = has_format_option(FO_INS_BLANK);

  /*
   * Try to break the line in two or more pieces when:
   * - Always do this if we have been called to do formatting only.
   * - Always do this when 'formatoptions' has the 'a' flag and the line
   *   ends in white space.
   * - Otherwise:
   *	 - Don't do this if inserting a blank
   *	 - Don't do this if an existing character is being replaced, unless
   *	   we're in VREPLACE mode.
   *	 - Do this if the cursor is not on the line where insert started
   *	 or - 'formatoptions' doesn't have 'l' or the line was not too long
   *	       before the insert.
   *	    - 'formatoptions' doesn't have 'b' or a blank was inserted at or
   *	      before 'textwidth'
   */
  if (textwidth > 0 &&
      (force_format ||
       (!VIM_ISWHITE(c) &&
        !((State & REPLACE_FLAG) && !(State & VREPLACE_FLAG) &&
          *ml_get_cursor() != NUL) &&
        (curwin->w_cursor.lnum != Insstart.lnum ||
         ((!has_format_option(FO_INS_LONG) ||
           Insstart_textlen <= (colnr_T)textwidth) &&
          (!fo_ins_blank || Insstart_blank_vcol <= (colnr_T)textwidth))))))
  {
    /* Format with 'formatexpr' when it's set.  Use internal formatting
     * when 'formatexpr' isn't set or it returns non-zero. */
#if defined(FEAT_EVAL)
    int do_internal = TRUE;
    colnr_T virtcol =
        get_nolist_virtcol() + char2cells(c != NUL ? c : gchar_cursor());

    if (*curbuf->b_p_fex != NUL && (flags & INSCHAR_NO_FEX) == 0 &&
        (force_format || virtcol > (colnr_T)textwidth))
    {
      do_internal = (fex_format(curwin->w_cursor.lnum, 1L, c) != 0);
      /* It may be required to save for undo again, e.g. when setline()
       * was called. */
      ins_need_undo = TRUE;
    }
    if (do_internal)
#endif
      internal_format(textwidth, second_indent, flags, c == NUL, c);
  }

  if (c == NUL) /* only formatting was wanted */
    return;

#ifdef FEAT_COMMENTS
  /* Check whether this character should end a comment. */
  if (did_ai && (int)c == end_comment_pending)
  {
    char_u *line;
    char_u lead_end[COM_MAX_LEN]; /* end-comment string */
    int middle_len, end_len;
    int i;

    /*
     * Need to remove existing (middle) comment leader and insert end
     * comment leader.  First, check what comment leader we can find.
     */
    i = get_leader_len(line = ml_get_curline(), &p, FALSE, TRUE);
    if (i > 0 && vim_strchr(p, COM_MIDDLE) != NULL) /* Just checking */
    {
      /* Skip middle-comment string */
      while (*p && p[-1] != ':') /* find end of middle flags */
        ++p;
      middle_len = copy_option_part(&p, lead_end, COM_MAX_LEN, ",");
      /* Don't count trailing white space for middle_len */
      while (middle_len > 0 && VIM_ISWHITE(lead_end[middle_len - 1]))
        --middle_len;

      /* Find the end-comment string */
      while (*p && p[-1] != ':') /* find end of end flags */
        ++p;
      end_len = copy_option_part(&p, lead_end, COM_MAX_LEN, ",");

      /* Skip white space before the cursor */
      i = curwin->w_cursor.col;
      while (--i >= 0 && VIM_ISWHITE(line[i]))
        ;
      i++;

      /* Skip to before the middle leader */
      i -= middle_len;

      /* Check some expected things before we go on */
      if (i >= 0 && lead_end[end_len - 1] == end_comment_pending)
      {
        /* Backspace over all the stuff we want to replace */
        backspace_until_column(i);

        /*
         * Insert the end-comment string, except for the last
         * character, which will get inserted as normal later.
         */
        ins_bytes_len(lead_end, end_len - 1);
      }
    }
  }
  end_comment_pending = NUL;
#endif

  did_ai = FALSE;
#ifdef FEAT_SMARTINDENT
  did_si = FALSE;
  can_si = FALSE;
  can_si_back = FALSE;
#endif

  /*
   * If there's any pending input, grab up to INPUT_BUFLEN at once.
   * This speeds up normal text input considerably.
   * Don't do this when 'cindent' or 'indentexpr' is set, because we might
   * need to re-indent at a ':', or any other character (but not what
   * 'paste' is set)..
   * Don't do this when there an InsertCharPre autocommand is defined,
   * because we need to fire the event for every character.
   * Do the check for InsertCharPre before the call to vpeekc() because the
   * InsertCharPre autocommand could change the input buffer.
   */
  if (!ISSPECIAL(c) && (!has_mbyte || (*mb_char2len)(c) == 1) &&
      !has_insertcharpre() && vpeekc() != NUL && !(State & REPLACE_FLAG)
#ifdef FEAT_RIGHTLEFT
      && !p_ri
#endif
  )
  {
#define INPUT_BUFLEN 100
    char_u buf[INPUT_BUFLEN + 1];
    int i;
    colnr_T virtcol = 0;

    buf[0] = c;
    i = 1;
    if (textwidth > 0)
      virtcol = get_nolist_virtcol();
    /*
     * Stop the string when:
     * - no more chars available
     * - finding a special character (command key)
     * - buffer is full
     * - running into the 'textwidth' boundary
     * - need to check for abbreviation: A non-word char after a word-char
     */
    while ((c = vpeekc()) != NUL && !ISSPECIAL(c) &&
           (!has_mbyte || MB_BYTE2LEN_CHECK(c) == 1) && i < INPUT_BUFLEN &&
           (textwidth == 0 ||
            (virtcol += byte2cells(buf[i - 1])) < (colnr_T)textwidth) &&
           !(!no_abbr && !vim_iswordc(c) && vim_iswordc(buf[i - 1])))
    {
#ifdef FEAT_RIGHTLEFT
      c = vgetc();
      if (p_hkmap && KeyTyped)
        c = hkmap(c); /* Hebrew mode mapping */
      buf[i++] = c;
#else
      buf[i++] = vgetc();
#endif
    }

#ifdef FEAT_DIGRAPHS
    do_digraph(-1);         /* clear digraphs */
    do_digraph(buf[i - 1]); /* may be the start of a digraph */
#endif
    buf[i] = NUL;
    ins_str(buf);
    if (flags & INSCHAR_CTRLV)
    {
      redo_literal(*buf);
      i = 1;
    }
    else
      i = 0;
    if (buf[i] != NUL)
      AppendToRedobuffLit(buf + i, -1);
  }
  else
  {
    int cc;

    if (has_mbyte && (cc = (*mb_char2len)(c)) > 1)
    {
      char_u buf[MB_MAXBYTES + 1];

      (*mb_char2bytes)(c, buf);
      buf[cc] = NUL;
      ins_char_bytes(buf, cc);
      AppendCharToRedobuff(c);
    }
    else
    {
      ins_char(c);
      if (flags & INSCHAR_CTRLV)
        redo_literal(c);
      else
        AppendCharToRedobuff(c);
    }
  }
}

/*
 * Format text at the current insert position.
 *
 * If the INSCHAR_COM_LIST flag is present, then the value of second_indent
 * will be the comment leader length sent to open_line().
 */
static void internal_format(int textwidth, int second_indent, int flags,
                            int format_only,
                            int c) /* character to be inserted (can be NUL) */
{
  int cc;
  int save_char = NUL;
  int haveto_redraw = FALSE;
  int fo_ins_blank = has_format_option(FO_INS_BLANK);
  int fo_multibyte = has_format_option(FO_MBYTE_BREAK);
  int fo_white_par = has_format_option(FO_WHITE_PAR);
  int first_line = TRUE;
#ifdef FEAT_COMMENTS
  colnr_T leader_len;
  int no_leader = FALSE;
  int do_comments = (flags & INSCHAR_DO_COM);
#endif
#ifdef FEAT_LINEBREAK
  int has_lbr = curwin->w_p_lbr;

  /* make sure win_lbr_chartabsize() counts correctly */
  curwin->w_p_lbr = FALSE;
#endif

  /*
   * When 'ai' is off we don't want a space under the cursor to be
   * deleted.  Replace it with an 'x' temporarily.
   */
  if (!curbuf->b_p_ai && !(State & VREPLACE_FLAG))
  {
    cc = gchar_cursor();
    if (VIM_ISWHITE(cc))
    {
      save_char = cc;
      pchar_cursor('x');
    }
  }

  /*
   * Repeat breaking lines, until the current line is not too long.
   */
  while (!got_int)
  {
    int startcol;         /* Cursor column at entry */
    int wantcol;          /* column at textwidth border */
    int foundcol;         /* column for start of spaces */
    int end_foundcol = 0; /* column for start of word */
    colnr_T len;
    colnr_T virtcol;
    int orig_col = 0;
    char_u *saved_text = NULL;
    colnr_T col;
    colnr_T end_col;
    int wcc; // counter for whitespace chars

    virtcol = get_nolist_virtcol() + char2cells(c != NUL ? c : gchar_cursor());
    if (virtcol <= (colnr_T)textwidth)
      break;

#ifdef FEAT_COMMENTS
    if (no_leader)
      do_comments = FALSE;
    else if (!(flags & INSCHAR_FORMAT) && has_format_option(FO_WRAP_COMS))
      do_comments = TRUE;

    /* Don't break until after the comment leader */
    if (do_comments)
      leader_len = get_leader_len(ml_get_curline(), NULL, FALSE, TRUE);
    else
      leader_len = 0;

    /* If the line doesn't start with a comment leader, then don't
     * start one in a following broken line.  Avoids that a %word
     * moved to the start of the next line causes all following lines
     * to start with %. */
    if (leader_len == 0)
      no_leader = TRUE;
#endif
    if (!(flags & INSCHAR_FORMAT)
#ifdef FEAT_COMMENTS
        && leader_len == 0
#endif
        && !has_format_option(FO_WRAP))

      break;
    if ((startcol = curwin->w_cursor.col) == 0)
      break;

    /* find column of textwidth border */
    coladvance((colnr_T)textwidth);
    wantcol = curwin->w_cursor.col;

    curwin->w_cursor.col = startcol;
    foundcol = 0;

    /*
     * Find position to break at.
     * Stop at first entered white when 'formatoptions' has 'v'
     */
    while ((!fo_ins_blank && !has_format_option(FO_INS_VI)) ||
           (flags & INSCHAR_FORMAT) || curwin->w_cursor.lnum != Insstart.lnum ||
           curwin->w_cursor.col >= Insstart.col)
    {
      if (curwin->w_cursor.col == startcol && c != NUL)
        cc = c;
      else
        cc = gchar_cursor();
      if (WHITECHAR(cc))
      {
        /* remember position of blank just before text */
        end_col = curwin->w_cursor.col;

        // find start of sequence of blanks
        wcc = 0;
        while (curwin->w_cursor.col > 0 && WHITECHAR(cc))
        {
          dec_cursor();
          cc = gchar_cursor();

          // Increment count of how many whitespace chars in this
          // group; we only need to know if it's more than one.
          if (wcc < 2)
            wcc++;
        }
        if (curwin->w_cursor.col == 0 && WHITECHAR(cc))
          break; /* only spaces in front of text */

        // Don't break after a period when 'formatoptions' has 'p' and
        // there are less than two spaces.
        if (has_format_option(FO_PERIOD_ABBR) && cc == '.' && wcc < 2)
          continue;

#ifdef FEAT_COMMENTS
        /* Don't break until after the comment leader */
        if (curwin->w_cursor.col < leader_len)
          break;
#endif
        if (has_format_option(FO_ONE_LETTER))
        {
          /* do not break after one-letter words */
          if (curwin->w_cursor.col == 0)
            break; /* one-letter word at begin */
#ifdef FEAT_COMMENTS
          /* do not break "#a b" when 'tw' is 2 */
          if (curwin->w_cursor.col <= leader_len)
            break;
#endif
          col = curwin->w_cursor.col;
          dec_cursor();
          cc = gchar_cursor();

          if (WHITECHAR(cc))
            continue; /* one-letter, continue */
          curwin->w_cursor.col = col;
        }

        inc_cursor();

        end_foundcol = end_col + 1;
        foundcol = curwin->w_cursor.col;
        if (curwin->w_cursor.col <= (colnr_T)wantcol)
          break;
      }
      else if (cc >= 0x100 && fo_multibyte)
      {
        /* Break after or before a multi-byte character. */
        if (curwin->w_cursor.col != startcol)
        {
#ifdef FEAT_COMMENTS
          /* Don't break until after the comment leader */
          if (curwin->w_cursor.col < leader_len)
            break;
#endif
          col = curwin->w_cursor.col;
          inc_cursor();
          /* Don't change end_foundcol if already set. */
          if (foundcol != curwin->w_cursor.col)
          {
            foundcol = curwin->w_cursor.col;
            end_foundcol = foundcol;
            if (curwin->w_cursor.col <= (colnr_T)wantcol)
              break;
          }
          curwin->w_cursor.col = col;
        }

        if (curwin->w_cursor.col == 0)
          break;

        col = curwin->w_cursor.col;

        dec_cursor();
        cc = gchar_cursor();

        if (WHITECHAR(cc))
          continue; /* break with space */
#ifdef FEAT_COMMENTS
        /* Don't break until after the comment leader */
        if (curwin->w_cursor.col < leader_len)
          break;
#endif

        curwin->w_cursor.col = col;

        foundcol = curwin->w_cursor.col;
        end_foundcol = foundcol;
        if (curwin->w_cursor.col <= (colnr_T)wantcol)
          break;
      }
      if (curwin->w_cursor.col == 0)
        break;
      dec_cursor();
    }

    if (foundcol == 0) /* no spaces, cannot break line */
    {
      curwin->w_cursor.col = startcol;
      break;
    }

    /* Going to break the line, remove any "$" now. */
    undisplay_dollar();

    /*
     * Offset between cursor position and line break is used by replace
     * stack functions.  VREPLACE does not use this, and backspaces
     * over the text instead.
     */
    if (State & VREPLACE_FLAG)
      orig_col = startcol; /* Will start backspacing from here */
    else
      replace_offset = startcol - end_foundcol;

    /*
     * adjust startcol for spaces that will be deleted and
     * characters that will remain on top line
     */
    curwin->w_cursor.col = foundcol;
    while ((cc = gchar_cursor(), WHITECHAR(cc)) &&
           (!fo_white_par || curwin->w_cursor.col < startcol))
      inc_cursor();
    startcol -= curwin->w_cursor.col;
    if (startcol < 0)
      startcol = 0;

    if (State & VREPLACE_FLAG)
    {
      /*
       * In VREPLACE mode, we will backspace over the text to be
       * wrapped, so save a copy now to put on the next line.
       */
      saved_text = vim_strsave(ml_get_cursor());
      curwin->w_cursor.col = orig_col;
      if (saved_text == NULL)
        break; /* Can't do it, out of memory */
      saved_text[startcol] = NUL;

      /* Backspace over characters that will move to the next line */
      if (!fo_white_par)
        backspace_until_column(foundcol);
    }
    else
    {
      /* put cursor after pos. to break line */
      if (!fo_white_par)
        curwin->w_cursor.col = foundcol;
    }

    /*
     * Split the line just before the margin.
     * Only insert/delete lines, but don't really redraw the window.
     */
    open_line(FORWARD,
              OPENLINE_DELSPACES + OPENLINE_MARKFIX +
                  (fo_white_par ? OPENLINE_KEEPTRAIL : 0)
#ifdef FEAT_COMMENTS
                  + (do_comments ? OPENLINE_DO_COM : 0) +
                  ((flags & INSCHAR_COM_LIST) ? OPENLINE_COM_LIST : 0)
#endif
                  ,
              ((flags & INSCHAR_COM_LIST) ? second_indent : old_indent));
    if (!(flags & INSCHAR_COM_LIST))
      old_indent = 0;

    replace_offset = 0;
    if (first_line)
    {
      if (!(flags & INSCHAR_COM_LIST))
      {
        /*
         * This section is for auto-wrap of numeric lists.  When not
         * in insert mode (i.e. format_lines()), the INSCHAR_COM_LIST
         * flag will be set and open_line() will handle it (as seen
         * above).  The code here (and in get_number_indent()) will
         * recognize comments if needed...
         */
        if (second_indent < 0 && has_format_option(FO_Q_NUMBER))
          second_indent = get_number_indent(curwin->w_cursor.lnum - 1);
        if (second_indent >= 0)
        {
          if (State & VREPLACE_FLAG)
            change_indent(INDENT_SET, second_indent, FALSE, NUL, TRUE);
          else
#ifdef FEAT_COMMENTS
              if (leader_len > 0 && second_indent - leader_len > 0)
          {
            int i;
            int padding = second_indent - leader_len;

            /* We started at the first_line of a numbered list
             * that has a comment.  the open_line() function has
             * inserted the proper comment leader and positioned
             * the cursor at the end of the split line.  Now we
             * add the additional whitespace needed after the
             * comment leader for the numbered list.  */
            for (i = 0; i < padding; i++)
              ins_str((char_u *)" ");
          }
          else
          {
#endif
            (void)set_indent(second_indent, SIN_CHANGED);
#ifdef FEAT_COMMENTS
          }
#endif
        }
      }
      first_line = FALSE;
    }

    if (State & VREPLACE_FLAG)
    {
      /*
       * In VREPLACE mode we have backspaced over the text to be
       * moved, now we re-insert it into the new line.
       */
      ins_bytes(saved_text);
      vim_free(saved_text);
    }
    else
    {
      /*
       * Check if cursor is not past the NUL off the line, cindent
       * may have added or removed indent.
       */
      curwin->w_cursor.col += startcol;
      len = (colnr_T)STRLEN(ml_get_curline());
      if (curwin->w_cursor.col > len)
        curwin->w_cursor.col = len;
    }

    haveto_redraw = TRUE;
    /* moved the cursor, don't autoindent or cindent now */
    did_ai = FALSE;
#ifdef FEAT_SMARTINDENT
    did_si = FALSE;
    can_si = FALSE;
    can_si_back = FALSE;
#endif
    line_breakcheck();
  }

  if (save_char != NUL) /* put back space after cursor */
    pchar_cursor(save_char);

#ifdef FEAT_LINEBREAK
  curwin->w_p_lbr = has_lbr;
#endif
  if (!format_only && haveto_redraw)
  {
    update_topline();
    redraw_curbuf_later(VALID);
  }
}

/*
 * Called after inserting or deleting text: When 'formatoptions' includes the
 * 'a' flag format from the current line until the end of the paragraph.
 * Keep the cursor at the same position relative to the text.
 * The caller must have saved the cursor line for undo, following ones will be
 * saved here.
 */
void auto_format(int trailblank, /* when TRUE also format with trailing blank */
                 int prev_line)  /* may start in previous line */
{
  pos_T pos;
  colnr_T len;
  char_u *old;
  char_u *new, *pnew;
  int wasatend;
  int cc;

  if (!has_format_option(FO_AUTO))
    return;

  pos = curwin->w_cursor;
  old = ml_get_curline();

  /* may remove added space */
  check_auto_format(FALSE);

  /* Don't format in Insert mode when the cursor is on a trailing blank, the
   * user might insert normal text next.  Also skip formatting when "1" is
   * in 'formatoptions' and there is a single character before the cursor.
   * Otherwise the line would be broken and when typing another non-white
   * next they are not joined back together. */
  wasatend = (pos.col == (colnr_T)STRLEN(old));
  if (*old != NUL && !trailblank && wasatend)
  {
    dec_cursor();
    cc = gchar_cursor();
    if (!WHITECHAR(cc) && curwin->w_cursor.col > 0 &&
        has_format_option(FO_ONE_LETTER))
      dec_cursor();
    cc = gchar_cursor();
    if (WHITECHAR(cc))
    {
      curwin->w_cursor = pos;
      return;
    }
    curwin->w_cursor = pos;
  }

#ifdef FEAT_COMMENTS
  /* With the 'c' flag in 'formatoptions' and 't' missing: only format
   * comments. */
  if (has_format_option(FO_WRAP_COMS) && !has_format_option(FO_WRAP) &&
      get_leader_len(old, NULL, FALSE, TRUE) == 0)
    return;
#endif

  /*
   * May start formatting in a previous line, so that after "x" a word is
   * moved to the previous line if it fits there now.  Only when this is not
   * the start of a paragraph.
   */
  if (prev_line && !paragraph_start(curwin->w_cursor.lnum))
  {
    --curwin->w_cursor.lnum;
    if (u_save_cursor() == FAIL)
      return;
  }

  /*
   * Do the formatting and restore the cursor position.  "saved_cursor" will
   * be adjusted for the text formatting.
   */
  saved_cursor = pos;
  format_lines((linenr_T)-1, FALSE);
  curwin->w_cursor = saved_cursor;
  saved_cursor.lnum = 0;

  if (curwin->w_cursor.lnum > curbuf->b_ml.ml_line_count)
  {
    /* "cannot happen" */
    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
    coladvance((colnr_T)MAXCOL);
  }
  else
    check_cursor_col();

  /* Insert mode: If the cursor is now after the end of the line while it
   * previously wasn't, the line was broken.  Because of the rule above we
   * need to add a space when 'w' is in 'formatoptions' to keep a paragraph
   * formatted. */
  if (!wasatend && has_format_option(FO_WHITE_PAR))
  {
    new = ml_get_curline();
    len = (colnr_T)STRLEN(new);
    if (curwin->w_cursor.col == len)
    {
      pnew = vim_strnsave(new, len + 2);
      pnew[len] = ' ';
      pnew[len + 1] = NUL;
      ml_replace(curwin->w_cursor.lnum, pnew, FALSE);
      /* remove the space later */
      did_add_space = TRUE;
    }
    else
      /* may remove added space */
      check_auto_format(FALSE);
  }

  check_cursor();
}

/*
 * When an extra space was added to continue a paragraph for auto-formatting,
 * delete it now.  The space must be under the cursor, just after the insert
 * position.
 */
static void check_auto_format(int end_insert) /* TRUE when ending Insert mode */
{
  int c = ' ';
  int cc;

  if (did_add_space)
  {
    cc = gchar_cursor();
    if (!WHITECHAR(cc))
      /* Somehow the space was removed already. */
      did_add_space = FALSE;
    else
    {
      if (!end_insert)
      {
        inc_cursor();
        c = gchar_cursor();
        dec_cursor();
      }
      if (c != NUL)
      {
        /* The space is no longer at the end of the line, delete it. */
        del_char(FALSE);
        did_add_space = FALSE;
      }
    }
  }
}

/*
 * Find out textwidth to be used for formatting:
 *	if 'textwidth' option is set, use it
 *	else if 'wrapmargin' option is set, use curwin->w_width - 'wrapmargin'
 *	if invalid value, use 0.
 *	Set default to window width (maximum 79) for "gq" operator.
 */
int comp_textwidth(int ff) /* force formatting (for "gq" command) */
{
  int textwidth;

  textwidth = curbuf->b_p_tw;
  if (textwidth == 0 && curbuf->b_p_wm)
  {
    /* The width is the window width minus 'wrapmargin' minus all the
     * things that add to the margin. */
    textwidth = curwin->w_width - curbuf->b_p_wm;
#ifdef FEAT_FOLDING
    textwidth -= curwin->w_p_fdc;
#endif
#ifdef FEAT_SIGNS
    if (signcolumn_on(curwin))
      textwidth -= 1;
#endif
    if (curwin->w_p_nu || curwin->w_p_rnu)
      textwidth -= 8;
  }
  if (textwidth < 0)
    textwidth = 0;
  if (ff && textwidth == 0)
  {
    textwidth = curwin->w_width - 1;
    if (textwidth > 79)
      textwidth = 79;
  }
  return textwidth;
}

/*
 * Put a character in the redo buffer, for when just after a CTRL-V.
 */
static void redo_literal(int c)
{
  char_u buf[10];

  /* Only digits need special treatment.  Translate them into a string of
   * three digits. */
  if (VIM_ISDIGIT(c))
  {
    vim_snprintf((char *)buf, sizeof(buf), "%03d", c);
    AppendToRedobuff(buf);
  }
  else
    AppendCharToRedobuff(c);
}

/*
 * start_arrow() is called when an arrow key is used in insert mode.
 * For undo/redo it resembles hitting the <ESC> key.
 */
void start_arrow(pos_T *end_insert_pos) /* can be NULL */
{
  start_arrow_common(end_insert_pos, TRUE);
}

/*
 * Like start_arrow() but with end_change argument.
 * Will prepare for redo of CTRL-G U if "end_change" is FALSE.
 */
static void start_arrow_with_change(pos_T *end_insert_pos, /* can be NULL */
                                    int end_change)        /* end undoable change */
{
  start_arrow_common(end_insert_pos, end_change);
  if (!end_change)
  {
    AppendCharToRedobuff(Ctrl_G);
    AppendCharToRedobuff('U');
  }
}

static void start_arrow_common(pos_T *end_insert_pos, /* can be NULL */
                               int end_change)        /* end undoable change */
{
  if (!arrow_used && end_change) /* something has been inserted */
  {
    AppendToRedobuff(ESC_STR);
    stop_insert(end_insert_pos, FALSE, FALSE);
    arrow_used = TRUE; /* this means we stopped the current insert */
  }
}

/*
 * stop_arrow() is called before a change is made in insert mode.
 * If an arrow key has been used, start a new insertion.
 * Returns FAIL if undo is impossible, shouldn't insert then.
 */
int stop_arrow(void)
{
  if (arrow_used)
  {
    Insstart = curwin->w_cursor; /* new insertion starts here */
    if (Insstart.col > Insstart_orig.col && !ins_need_undo)
      /* Don't update the original insert position when moved to the
       * right, except when nothing was inserted yet. */
      update_Insstart_orig = FALSE;
    Insstart_textlen = (colnr_T)linetabsize(ml_get_curline());

    if (u_save_cursor() == OK)
    {
      arrow_used = FALSE;
      ins_need_undo = FALSE;
    }

    ai_col = 0;
    if (State & VREPLACE_FLAG)
    {
      orig_line_count = curbuf->b_ml.ml_line_count;
      vr_lines_changed = 1;
    }
    ResetRedobuff();
    AppendToRedobuff((char_u *)"1i"); /* pretend we start an insertion */
    new_insert_skip = 2;
  }
  else if (ins_need_undo)
  {
    if (u_save_cursor() == OK)
      ins_need_undo = FALSE;
  }

#ifdef FEAT_FOLDING
  /* Always open fold at the cursor line when inserting something. */
  foldOpenCursor();
#endif

  return (arrow_used || ins_need_undo ? FAIL : OK);
}

/*
 * Do a few things to stop inserting.
 * "end_insert_pos" is where insert ended.  It is NULL when we already jumped
 * to another window/buffer.
 */
static void stop_insert(pos_T *end_insert_pos,
                        int esc,    /* called by ins_esc() */
                        int nomove) /* <c-\><c-o>, don't move cursor */
{
  int cc;
  char_u *ptr;

  stop_redo_ins();
  replace_flush(); /* abandon replace stack */

  /*
   * Save the inserted text for later redo with ^@ and CTRL-A.
   * Don't do it when "restart_edit" was set and nothing was inserted,
   * otherwise CTRL-O w and then <Left> will clear "last_insert".
   */
  ptr = get_inserted();
  if (did_restart_edit == 0 ||
      (ptr != NULL && (int)STRLEN(ptr) > new_insert_skip))
  {
    vim_free(last_insert);
    last_insert = ptr;
    last_insert_skip = new_insert_skip;
  }
  else
    vim_free(ptr);

  if (!arrow_used && end_insert_pos != NULL)
  {
    /* Auto-format now.  It may seem strange to do this when stopping an
     * insertion (or moving the cursor), but it's required when appending
     * a line and having it end in a space.  But only do it when something
     * was actually inserted, otherwise undo won't work. */
    if (!ins_need_undo && has_format_option(FO_AUTO))
    {
      pos_T tpos = curwin->w_cursor;

      /* When the cursor is at the end of the line after a space the
       * formatting will move it to the following word.  Avoid that by
       * moving the cursor onto the space. */
      cc = 'x';
      if (curwin->w_cursor.col > 0 && gchar_cursor() == NUL)
      {
        dec_cursor();
        cc = gchar_cursor();
        if (!VIM_ISWHITE(cc))
          curwin->w_cursor = tpos;
      }

      auto_format(TRUE, FALSE);

      if (VIM_ISWHITE(cc))
      {
        if (gchar_cursor() != NUL)
          inc_cursor();
        // If the cursor is still at the same character, also keep
        // the "coladd".
        if (gchar_cursor() == NUL && curwin->w_cursor.lnum == tpos.lnum &&
            curwin->w_cursor.col == tpos.col)
          curwin->w_cursor.coladd = tpos.coladd;
      }
    }

    /* If a space was inserted for auto-formatting, remove it now. */
    check_auto_format(TRUE);

    /* If we just did an auto-indent, remove the white space from the end
     * of the line, and put the cursor back.
     * Do this when ESC was used or moving the cursor up/down.
     * Check for the old position still being valid, just in case the text
     * got changed unexpectedly. */
    if (!nomove && did_ai &&
        (esc || (vim_strchr(p_cpo, CPO_INDENT) == NULL &&
                 curwin->w_cursor.lnum != end_insert_pos->lnum)) &&
        end_insert_pos->lnum <= curbuf->b_ml.ml_line_count)
    {
      pos_T tpos = curwin->w_cursor;

      curwin->w_cursor = *end_insert_pos;
      check_cursor_col(); /* make sure it is not past the line */
      for (;;)
      {
        if (gchar_cursor() == NUL && curwin->w_cursor.col > 0)
          --curwin->w_cursor.col;
        cc = gchar_cursor();
        if (!VIM_ISWHITE(cc))
          break;
        if (del_char(TRUE) == FAIL)
          break; /* should not happen */
      }
      if (curwin->w_cursor.lnum != tpos.lnum)
        curwin->w_cursor = tpos;
      else
      {
        /* reset tpos, could have been invalidated in the loop above */
        tpos = curwin->w_cursor;
        tpos.col++;
        if (cc != NUL && gchar_pos(&tpos) == NUL)
          ++curwin->w_cursor.col; /* put cursor back on the NUL */
      }

      /* <C-S-Right> may have started Visual mode, adjust the position for
       * deleted characters. */
      if (VIsual_active && VIsual.lnum == curwin->w_cursor.lnum)
      {
        int len = (int)STRLEN(ml_get_curline());

        if (VIsual.col > len)
        {
          VIsual.col = len;
          VIsual.coladd = 0;
        }
      }
    }
  }
  did_ai = FALSE;
#ifdef FEAT_SMARTINDENT
  did_si = FALSE;
  can_si = FALSE;
  can_si_back = FALSE;
#endif

  /* Set '[ and '] to the inserted text.  When end_insert_pos is NULL we are
   * now in a different buffer. */
  if (end_insert_pos != NULL)
  {
    curbuf->b_op_start = Insstart;
    curbuf->b_op_start_orig = Insstart_orig;
    curbuf->b_op_end = *end_insert_pos;
  }
}

/*
 * Set the last inserted text to a single character.
 * Used for the replace command.
 */
void set_last_insert(int c)
{
  char_u *s;

  vim_free(last_insert);
  last_insert = alloc(MB_MAXBYTES * 3 + 5);
  if (last_insert != NULL)
  {
    s = last_insert;
    /* Use the CTRL-V only when entering a special char */
    if (c < ' ' || c == DEL)
      *s++ = Ctrl_V;
    s = add_char2buf(c, s);
    *s++ = ESC;
    *s++ = NUL;
    last_insert_skip = 0;
  }
}

#if defined(EXITFREE) || defined(PROTO)
void free_last_insert(void)
{
  VIM_CLEAR(last_insert);
}
#endif

/*
 * Add character "c" to buffer "s".  Escape the special meaning of K_SPECIAL
 * and CSI.  Handle multi-byte characters.
 * Returns a pointer to after the added bytes.
 */
char_u *add_char2buf(int c, char_u *s)
{
  char_u temp[MB_MAXBYTES + 1];
  int i;
  int len;

  len = (*mb_char2bytes)(c, temp);
  for (i = 0; i < len; ++i)
  {
    c = temp[i];
    /* Need to escape K_SPECIAL and CSI like in the typeahead buffer. */
    if (c == K_SPECIAL)
    {
      *s++ = K_SPECIAL;
      *s++ = KS_SPECIAL;
      *s++ = KE_FILLER;
    }
    else
      *s++ = c;
  }
  return s;
}

/*
 * move cursor to start of line
 * if flags & BL_WHITE	move to first non-white
 * if flags & BL_SOL	move to first non-white if startofline is set,
 *			    otherwise keep "curswant" column
 * if flags & BL_FIX	don't leave the cursor on a NUL.
 */
void beginline(int flags)
{
  if ((flags & BL_SOL) && !p_sol)
    coladvance(curwin->w_curswant);
  else
  {
    curwin->w_cursor.col = 0;
    curwin->w_cursor.coladd = 0;

    if (flags & (BL_WHITE | BL_SOL))
    {
      char_u *ptr;

      for (ptr = ml_get_curline();
           VIM_ISWHITE(*ptr) && !((flags & BL_FIX) && ptr[1] == NUL); ++ptr)
        ++curwin->w_cursor.col;
    }
    curwin->w_set_curswant = TRUE;
  }
}

/*
 * oneright oneleft cursor_down cursor_up
 *
 * Move one char {right,left,down,up}.
 * Doesn't move onto the NUL past the end of the line, unless it is allowed.
 * Return OK when successful, FAIL when we hit a line of file boundary.
 */

int oneright(void)
{
  char_u *ptr;
  int l;

  if (virtual_active())
  {
    pos_T prevpos = curwin->w_cursor;

    /* Adjust for multi-wide char (excluding TAB) */
    ptr = ml_get_cursor();
    coladvance(getviscol() + ((*ptr != TAB && vim_isprintc((*mb_ptr2char)(ptr)))
                                  ? ptr2cells(ptr)
                                  : 1));
    curwin->w_set_curswant = TRUE;
    /* Return OK if the cursor moved, FAIL otherwise (at window edge). */
    return (prevpos.col != curwin->w_cursor.col ||
            prevpos.coladd != curwin->w_cursor.coladd)
               ? OK
               : FAIL;
  }

  ptr = ml_get_cursor();
  if (*ptr == NUL)
    return FAIL; /* already at the very end */

  if (has_mbyte)
    l = (*mb_ptr2len)(ptr);
  else
    l = 1;

  /* move "l" bytes right, but don't end up on the NUL, unless 'virtualedit'
   * contains "onemore". */
  if (ptr[l] == NUL && (ve_flags & VE_ONEMORE) == 0)
    return FAIL;
  curwin->w_cursor.col += l;

  curwin->w_set_curswant = TRUE;
  return OK;
}

int oneleft(void)
{
  if (virtual_active())
  {
#ifdef FEAT_LINEBREAK
    int width;
#endif
    int v = getviscol();

    if (v == 0)
      return FAIL;

#ifdef FEAT_LINEBREAK
    /* We might get stuck on 'showbreak', skip over it. */
    width = 1;
    for (;;)
    {
      coladvance(v - width);
      /* getviscol() is slow, skip it when 'showbreak' is empty,
       * 'breakindent' is not set and there are no multi-byte
       * characters */
      if ((*p_sbr == NUL && !curwin->w_p_bri && !has_mbyte) || getviscol() < v)
        break;
      ++width;
    }
#else
    coladvance(v - 1);
#endif

    if (curwin->w_cursor.coladd == 1)
    {
      char_u *ptr;

      /* Adjust for multi-wide char (not a TAB) */
      ptr = ml_get_cursor();
      if (*ptr != TAB && vim_isprintc((*mb_ptr2char)(ptr)) &&
          ptr2cells(ptr) > 1)
        curwin->w_cursor.coladd = 0;
    }

    curwin->w_set_curswant = TRUE;
    return OK;
  }

  if (curwin->w_cursor.col == 0)
    return FAIL;

  curwin->w_set_curswant = TRUE;
  --curwin->w_cursor.col;

  /* if the character on the left of the current cursor is a multi-byte
   * character, move to its first byte */
  if (has_mbyte)
    mb_adjust_cursor();
  return OK;
}

int cursor_up(long n, int upd_topline) /* When TRUE: update topline */
{
  linenr_T lnum;

  if (n > 0)
  {
    lnum = curwin->w_cursor.lnum;
    /* This fails if the cursor is already in the first line or the count
     * is larger than the line number and '-' is in 'cpoptions' */
    if (lnum <= 1 || (n >= lnum && vim_strchr(p_cpo, CPO_MINUS) != NULL))
      return FAIL;
    if (n >= lnum)
      lnum = 1;
    else
#ifdef FEAT_FOLDING
        if (hasAnyFolding(curwin))
    {
      /*
       * Count each sequence of folded lines as one logical line.
       */
      /* go to the start of the current fold */
      (void)hasFolding(lnum, &lnum, NULL);

      while (n--)
      {
        /* move up one line */
        --lnum;
        if (lnum <= 1)
          break;
        /* If we entered a fold, move to the beginning, unless in
         * Insert mode or when 'foldopen' contains "all": it will open
         * in a moment. */
        if (n > 0 || !((State & INSERT) || (fdo_flags & FDO_ALL)))
          (void)hasFolding(lnum, &lnum, NULL);
      }
      if (lnum < 1)
        lnum = 1;
    }
    else
#endif
      lnum -= n;
    curwin->w_cursor.lnum = lnum;
  }

  /* try to advance to the column we want to be at */
  coladvance(curwin->w_curswant);

  if (upd_topline)
    update_topline(); /* make sure curwin->w_topline is valid */

  return OK;
}

/*
 * Cursor down a number of logical lines.
 */
int cursor_down(long n, int upd_topline) /* When TRUE: update topline */
{
  linenr_T lnum;

  if (n > 0)
  {
    lnum = curwin->w_cursor.lnum;
#ifdef FEAT_FOLDING
    /* Move to last line of fold, will fail if it's the end-of-file. */
    (void)hasFolding(lnum, NULL, &lnum);
#endif
    /* This fails if the cursor is already in the last line or would move
     * beyond the last line and '-' is in 'cpoptions' */
    if (lnum >= curbuf->b_ml.ml_line_count ||
        (lnum + n > curbuf->b_ml.ml_line_count &&
         vim_strchr(p_cpo, CPO_MINUS) != NULL))
      return FAIL;
    if (lnum + n >= curbuf->b_ml.ml_line_count)
      lnum = curbuf->b_ml.ml_line_count;
    else
#ifdef FEAT_FOLDING
        if (hasAnyFolding(curwin))
    {
      linenr_T last;

      /* count each sequence of folded lines as one logical line */
      while (n--)
      {
        if (hasFolding(lnum, NULL, &last))
          lnum = last + 1;
        else
          ++lnum;
        if (lnum >= curbuf->b_ml.ml_line_count)
          break;
      }
      if (lnum > curbuf->b_ml.ml_line_count)
        lnum = curbuf->b_ml.ml_line_count;
    }
    else
#endif
      lnum += n;
    curwin->w_cursor.lnum = lnum;
  }

  /* try to advance to the column we want to be at */
  coladvance(curwin->w_curswant);

  if (upd_topline)
    update_topline(); /* make sure curwin->w_topline is valid */

  return OK;
}

/*
 * Stuff the last inserted text in the read buffer.
 * Last_insert actually is a copy of the redo buffer, so we
 * first have to remove the command.
 */
int stuff_inserted(int c,      /* Command character to be inserted */
                   long count, /* Repeat this many times */
                   int no_esc) /* Don't add an ESC at the end */
{
  char_u *esc_ptr;
  char_u *ptr;
  char_u *last_ptr;
  char_u last = NUL;

  ptr = get_last_insert();
  if (ptr == NULL)
  {
    emsg(_(e_noinstext));
    return FAIL;
  }

  /* may want to stuff the command character, to start Insert mode */
  if (c != NUL)
    stuffcharReadbuff(c);
  if ((esc_ptr = (char_u *)vim_strrchr(ptr, ESC)) != NULL)
    *esc_ptr = NUL; /* remove the ESC */

  /* when the last char is either "0" or "^" it will be quoted if no ESC
   * comes after it OR if it will inserted more than once and "ptr"
   * starts with ^D.	-- Acevedo
   */
  last_ptr = (esc_ptr ? esc_ptr : ptr + STRLEN(ptr)) - 1;
  if (last_ptr >= ptr && (*last_ptr == '0' || *last_ptr == '^') &&
      (no_esc || (*ptr == Ctrl_D && count > 1)))
  {
    last = *last_ptr;
    *last_ptr = NUL;
  }

  do
  {
    stuffReadbuff(ptr);
    /* a trailing "0" is inserted as "<C-V>048", "^" as "<C-V>^" */
    if (last)
      stuffReadbuff((char_u *)(last == '0'
                                   ? IF_EB("\026\060\064\070", CTRL_V_STR "xf0")
                                   : IF_EB("\026^", CTRL_V_STR "^")));
  } while (--count > 0);

  if (last)
    *last_ptr = last;

  if (esc_ptr != NULL)
    *esc_ptr = ESC; /* put the ESC back */

  /* may want to stuff a trailing ESC, to get out of Insert mode */
  if (!no_esc)
    stuffcharReadbuff(ESC);

  return OK;
}

char_u *get_last_insert(void)
{
  if (last_insert == NULL)
    return NULL;
  return last_insert + last_insert_skip;
}

/*
 * Get last inserted string, and remove trailing <Esc>.
 * Returns pointer to allocated memory (must be freed) or NULL.
 */
char_u *get_last_insert_save(void)
{
  char_u *s;
  int len;

  if (last_insert == NULL)
    return NULL;
  s = vim_strsave(last_insert + last_insert_skip);
  if (s != NULL)
  {
    len = (int)STRLEN(s);
    if (len > 0 && s[len - 1] == ESC) /* remove trailing ESC */
      s[len - 1] = NUL;
  }
  return s;
}

/*
 * Check the word in front of the cursor for an abbreviation.
 * Called when the non-id character "c" has been entered.
 * When an abbreviation is recognized it is removed from the text and
 * the replacement string is inserted in typebuf.tb_buf[], followed by "c".
 */
static int echeck_abbr(int c)
{
  /* Don't check for abbreviation in paste mode, when disabled and just
   * after moving around with cursor keys. */
  if (p_paste || no_abbr || arrow_used)
    return FALSE;

  return check_abbr(c, ml_get_curline(), curwin->w_cursor.col,
                    curwin->w_cursor.lnum == Insstart.lnum ? Insstart.col : 0);
}

/*
 * replace-stack functions
 *
 * When replacing characters, the replaced characters are remembered for each
 * new character.  This is used to re-insert the old text when backspacing.
 *
 * There is a NUL headed list of characters for each character that is
 * currently in the file after the insertion point.  When BS is used, one NUL
 * headed list is put back for the deleted character.
 *
 * For a newline, there are two NUL headed lists.  One contains the characters
 * that the NL replaced.  The extra one stores the characters after the cursor
 * that were deleted (always white space).
 *
 * Replace_offset is normally 0, in which case replace_push will add a new
 * character at the end of the stack.  If replace_offset is not 0, that many
 * characters will be left on the stack above the newly inserted character.
 */

static char_u *replace_stack = NULL;
static long replace_stack_nr = 0;  /* next entry in replace stack */
static long replace_stack_len = 0; /* max. number of entries */

void replace_push(int c) /* character that is replaced (NUL is none) */
{
  char_u *p;

  if (replace_stack_nr < replace_offset) /* nothing to do */
    return;
  if (replace_stack_len <= replace_stack_nr)
  {
    replace_stack_len += 50;
    p = ALLOC_MULT(char_u, replace_stack_len);
    if (p == NULL) /* out of memory */
    {
      replace_stack_len -= 50;
      return;
    }
    if (replace_stack != NULL)
    {
      mch_memmove(p, replace_stack,
                  (size_t)(replace_stack_nr * sizeof(char_u)));
      vim_free(replace_stack);
    }
    replace_stack = p;
  }
  p = replace_stack + replace_stack_nr - replace_offset;
  if (replace_offset)
    mch_memmove(p + 1, p, (size_t)(replace_offset * sizeof(char_u)));
  *p = c;
  ++replace_stack_nr;
}

/*
 * Push a character onto the replace stack.  Handles a multi-byte character in
 * reverse byte order, so that the first byte is popped off first.
 * Return the number of bytes done (includes composing characters).
 */
int replace_push_mb(char_u *p)
{
  int l = (*mb_ptr2len)(p);
  int j;

  for (j = l - 1; j >= 0; --j)
    replace_push(p[j]);
  return l;
}

/*
 * Pop one item from the replace stack.
 * return -1 if stack empty
 * return replaced character or NUL otherwise
 */
static int replace_pop(void)
{
  if (replace_stack_nr == 0)
    return -1;
  return (int)replace_stack[--replace_stack_nr];
}

/*
 * Join the top two items on the replace stack.  This removes to "off"'th NUL
 * encountered.
 */
static void replace_join(int off) /* offset for which NUL to remove */
{
  int i;

  for (i = replace_stack_nr; --i >= 0;)
    if (replace_stack[i] == NUL && off-- <= 0)
    {
      --replace_stack_nr;
      mch_memmove(replace_stack + i, replace_stack + i + 1,
                  (size_t)(replace_stack_nr - i));
      return;
    }
}

/*
 * Pop bytes from the replace stack until a NUL is found, and insert them
 * before the cursor.  Can only be used in REPLACE or VREPLACE mode.
 */
static void replace_pop_ins(void)
{
  int cc;
  int oldState = State;

  State = NORMAL; /* don't want REPLACE here */
  while ((cc = replace_pop()) > 0)
  {
    mb_replace_pop_ins(cc);
    dec_cursor();
  }
  State = oldState;
}

/*
 * Insert bytes popped from the replace stack. "cc" is the first byte.  If it
 * indicates a multi-byte char, pop the other bytes too.
 */
static void mb_replace_pop_ins(int cc)
{
  int n;
  char_u buf[MB_MAXBYTES + 1];
  int i;
  int c;

  if (has_mbyte && (n = MB_BYTE2LEN(cc)) > 1)
  {
    buf[0] = cc;
    for (i = 1; i < n; ++i)
      buf[i] = replace_pop();
    ins_bytes_len(buf, n);
  }
  else
    ins_char(cc);

  if (enc_utf8)
    /* Handle composing chars. */
    for (;;)
    {
      c = replace_pop();
      if (c == -1) /* stack empty */
        break;
      if ((n = MB_BYTE2LEN(c)) == 1)
      {
        /* Not a multi-byte char, put it back. */
        replace_push(c);
        break;
      }
      else
      {
        buf[0] = c;
        for (i = 1; i < n; ++i)
          buf[i] = replace_pop();
        if (utf_iscomposing(utf_ptr2char(buf)))
          ins_bytes_len(buf, n);
        else
        {
          /* Not a composing char, put it back. */
          for (i = n - 1; i >= 0; --i)
            replace_push(buf[i]);
          break;
        }
      }
    }
}

/*
 * make the replace stack empty
 * (called when exiting replace mode)
 */
static void replace_flush(void)
{
  VIM_CLEAR(replace_stack);
  replace_stack_len = 0;
  replace_stack_nr = 0;
}

/*
 * Handle doing a BS for one character.
 * cc < 0: replace stack empty, just move cursor
 * cc == 0: character was inserted, delete it
 * cc > 0: character was replaced, put cc (first byte of original char) back
 * and check for more characters to be put back
 * When "limit_col" is >= 0, don't delete before this column.  Matters when
 * using composing characters, use del_char_after_col() instead of del_char().
 */
static void replace_do_bs(int limit_col)
{
  int cc;
  int orig_len = 0;
  int ins_len;
  int orig_vcols = 0;
  colnr_T start_vcol;
  char_u *p;
  int i;
  int vcol;

  cc = replace_pop();
  if (cc > 0)
  {
    if (State & VREPLACE_FLAG)
    {
      /* Get the number of screen cells used by the character we are
       * going to delete. */
      getvcol(curwin, &curwin->w_cursor, NULL, &start_vcol, NULL);
      orig_vcols = chartabsize(ml_get_cursor(), start_vcol);
    }
    if (has_mbyte)
    {
      (void)del_char_after_col(limit_col);
      if (State & VREPLACE_FLAG)
        orig_len = (int)STRLEN(ml_get_cursor());
      replace_push(cc);
    }
    else
    {
      pchar_cursor(cc);
      if (State & VREPLACE_FLAG)
        orig_len = (int)STRLEN(ml_get_cursor()) - 1;
    }
    replace_pop_ins();

    if (State & VREPLACE_FLAG)
    {
      /* Get the number of screen cells used by the inserted characters */
      p = ml_get_cursor();
      ins_len = (int)STRLEN(p) - orig_len;
      vcol = start_vcol;
      for (i = 0; i < ins_len; ++i)
      {
        vcol += chartabsize(p + i, vcol);
        i += (*mb_ptr2len)(p)-1;
      }
      vcol -= start_vcol;

      /* Delete spaces that were inserted after the cursor to keep the
       * text aligned. */
      curwin->w_cursor.col += ins_len;
      while (vcol > orig_vcols && gchar_cursor() == ' ')
      {
        del_char(FALSE);
        ++orig_vcols;
      }
      curwin->w_cursor.col -= ins_len;
    }

    // mark the buffer as changed and prepare for displaying
    changed_bytes(curwin->w_cursor.lnum, curwin->w_cursor.col);
  }
  else if (cc == 0)
    (void)del_char_after_col(limit_col);
}

#if defined(FEAT_RIGHTLEFT) || defined(PROTO)
/*
 * Map Hebrew keyboard when in hkmap mode.
 */
int hkmap(int c)
{
  if (p_hkmapp) /* phonetic mapping, by Ilya Dogolazky */
  {
    enum
    {
      hALEF = 0,
      BET,
      GIMEL,
      DALET,
      HEI,
      VAV,
      ZAIN,
      HET,
      TET,
      IUD,
      KAFsofit,
      hKAF,
      LAMED,
      MEMsofit,
      MEM,
      NUNsofit,
      NUN,
      SAMEH,
      AIN,
      PEIsofit,
      PEI,
      ZADIsofit,
      ZADI,
      KOF,
      RESH,
      hSHIN,
      TAV
    };
    static char_u map[26] = {
        (char_u)hALEF /*a*/, (char_u)BET /*b*/, (char_u)hKAF /*c*/,
        (char_u)DALET /*d*/, (char_u)-1 /*e*/, (char_u)PEIsofit /*f*/,
        (char_u)GIMEL /*g*/, (char_u)HEI /*h*/, (char_u)IUD /*i*/,
        (char_u)HET /*j*/, (char_u)KOF /*k*/, (char_u)LAMED /*l*/,
        (char_u)MEM /*m*/, (char_u)NUN /*n*/, (char_u)SAMEH /*o*/,
        (char_u)PEI /*p*/, (char_u)-1 /*q*/, (char_u)RESH /*r*/,
        (char_u)ZAIN /*s*/, (char_u)TAV /*t*/, (char_u)TET /*u*/,
        (char_u)VAV /*v*/, (char_u)hSHIN /*w*/, (char_u)-1 /*x*/,
        (char_u)AIN /*y*/, (char_u)ZADI /*z*/};

    if (c == 'N' || c == 'M' || c == 'P' || c == 'C' || c == 'Z')
      return (int)(map[CharOrd(c)] - 1 + p_aleph);
    /* '-1'='sofit' */
    else if (c == 'x')
      return 'X';
    else if (c == 'q')
      return '\''; /* {geresh}={'} */
    else if (c == 246)
      return ' '; /* \"o --> ' ' for a german keyboard */
    else if (c == 228)
      return ' '; /* \"a --> ' '      -- / --	       */
    else if (c == 252)
      return ' '; /* \"u --> ' '      -- / --	       */
#ifdef EBCDIC
    else if (islower(c))
#else
    /* NOTE: islower() does not do the right thing for us on Linux so we
     * do this the same was as 5.7 and previous, so it works correctly on
     * all systems.  Specifically, the e.g. Delete and Arrow keys are
     * munged and won't work if e.g. searching for Hebrew text.
     */
    else if (c >= 'a' && c <= 'z')
#endif
      return (int)(map[CharOrdLow(c)] + p_aleph);
    else
      return c;
  }
  else
  {
    switch (c)
    {
    case '`':
      return ';';
    case '/':
      return '.';
    case '\'':
      return ',';
    case 'q':
      return '/';
    case 'w':
      return '\'';

      /* Hebrew letters - set offset from 'a' */
    case ',':
      c = '{';
      break;
    case '.':
      c = 'v';
      break;
    case ';':
      c = 't';
      break;
    default:
    {
      static char str[] = "zqbcxlsjphmkwonu ydafe rig";

#ifdef EBCDIC
      /* see note about islower() above */
      if (!islower(c))
#else
      if (c < 'a' || c > 'z')
#endif
        return c;
      c = str[CharOrdLow(c)];
      break;
    }
    }

    return (int)(CharOrdLow(c) + p_aleph);
  }
}
#endif

/*
 * CTRL-G commands in Insert mode.
 */
static void ins_ctrl_g_nonblocking(int c)
{
  switch (c)
  {
  /* CTRL-G k and CTRL-G <Up>: cursor up to Insstart.col */
  case K_UP:
  case Ctrl_K:
  case 'k':
    ins_up(TRUE);
    break;

  /* CTRL-G j and CTRL-G <Down>: cursor down to Insstart.col */
  case K_DOWN:
  case Ctrl_J:
  case 'j':
    ins_down(TRUE);
    break;

  /* CTRL-G u: start new undoable edit */
  case 'u':
    u_sync(TRUE);
    ins_need_undo = TRUE;

    /* Need to reset Insstart, esp. because a BS that joins
     * a line to the previous one must save for undo. */
    update_Insstart_orig = FALSE;
    Insstart = curwin->w_cursor;
    break;

  /* CTRL-G U: do not break undo with the next char */
  case 'U':
    /* Allow one left/right cursor movement with the next char,
     * without breaking undo. */
    dont_sync_undo = MAYBE;
    break;

  /* Unknown CTRL-G command, reserved for future expansion. */
  default:
    vim_beep(BO_CTRLG);
  }
}

/*
 * CTRL-G commands in Insert mode.
 */
static void ins_ctrl_g(void)
{
  int c;

  /*
   * Don't map the second key. This also prevents the mode message to be
   * deleted when ESC is hit.
   */
  ++no_mapping;
  c = plain_vgetc();
  --no_mapping;
  ins_ctrl_g_nonblocking(c);
}

/*
 * CTRL-^ in Insert mode.
 */
static void ins_ctrl_hat(void)
{
  if (map_to_exists_mode((char_u *)"", LANGMAP, FALSE))
  {
    /* ":lmap" mappings exists, Toggle use of ":lmap" mappings. */
    if (State & LANGMAP)
    {
      curbuf->b_p_iminsert = B_IMODE_NONE;
      State &= ~LANGMAP;
    }
    else
    {
      curbuf->b_p_iminsert = B_IMODE_LMAP;
      State |= LANGMAP;
    }
  }
  set_iminsert_global();
#if defined(FEAT_KEYMAP)
  /* Show/unshow value of 'keymap' in status lines. */
  status_redraw_curbuf();
#endif
}

/*
 * Handle ESC in insert mode.
 * Returns TRUE when leaving insert mode, FALSE when going to repeat the
 * insert.
 */
static int ins_esc(long *count, int cmdchar, int nomove) /* don't move cursor */
{
  int temp;
  static int disabled_redraw = FALSE;

  temp = curwin->w_cursor.col;
  if (disabled_redraw)
  {
    --RedrawingDisabled;
    disabled_redraw = FALSE;
  }
  if (!arrow_used)
  {
    /*
     * Don't append the ESC for "r<CR>" and "grx".
     * When 'insertmode' is set only CTRL-L stops Insert mode.  Needed for
     * when "count" is non-zero.
     */
    if (cmdchar != 'r' && cmdchar != 'v')
      AppendToRedobuff(p_im ? (char_u *)"\014" : ESC_STR);

    /*
     * Repeating insert may take a long time.  Check for
     * interrupt now and then.
     */
    if (*count > 0)
    {
      line_breakcheck();
      if (got_int)
        *count = 0;
    }

    if (--*count > 0) /* repeat what was typed */
    {
      /* Vi repeats the insert without replacing characters. */
      if (vim_strchr(p_cpo, CPO_REPLCNT) != NULL)
        State &= ~REPLACE_FLAG;

      (void)start_redo_ins();
      if (cmdchar == 'r' || cmdchar == 'v')
        stuffRedoReadbuff(ESC_STR); /* no ESC in redo buffer */
      ++RedrawingDisabled;
      disabled_redraw = TRUE;
      return FALSE; /* repeat the insert */
    }
    stop_insert(&curwin->w_cursor, TRUE, nomove);
    undisplay_dollar();
  }

  /* When an autoindent was removed, curswant stays after the
   * indent */
  if (restart_edit == NUL && (colnr_T)temp == curwin->w_cursor.col)
    curwin->w_set_curswant = TRUE;

  /* Remember the last Insert position in the '^ mark. */
  if (!cmdmod.keepjumps)
    curbuf->b_last_insert = curwin->w_cursor;

  /*
   * The cursor should end up on the last inserted character.
   * Don't do it for CTRL-O, unless past the end of the line.
   */
  if (!nomove && (curwin->w_cursor.col != 0 || curwin->w_cursor.coladd > 0) &&
      (restart_edit == NUL || (gchar_cursor() == NUL && !VIsual_active))
#ifdef FEAT_RIGHTLEFT
      && !revins_on
#endif
  )
  {
    if (curwin->w_cursor.coladd > 0 || ve_flags == VE_ALL)
    {
      oneleft();
      if (restart_edit != NUL)
        ++curwin->w_cursor.coladd;
    }
    else
    {
      --curwin->w_cursor.col;
      /* Correct cursor for multi-byte character. */
      if (has_mbyte)
        mb_adjust_cursor();
    }
  }

  State = NORMAL;
  /* need to position cursor again (e.g. when on a TAB ) */
  changed_cline_bef_curs();

  if (!p_ek)
    /* Re-enable bracketed paste mode. */
    out_str(T_BE);

  return TRUE; /* exit Insert mode */
}

#ifdef FEAT_RIGHTLEFT
/*
 * Toggle language: hkmap and revins_on.
 * Move to end of reverse inserted text.
 */
static void ins_ctrl_(void)
{
  if (revins_on && revins_chars && revins_scol >= 0)
  {
    while (gchar_cursor() != NUL && revins_chars--)
      ++curwin->w_cursor.col;
  }
  p_ri = !p_ri;
  revins_on = (State == INSERT && p_ri);
  if (revins_on)
  {
    revins_scol = curwin->w_cursor.col;
    revins_legal++;
    revins_chars = 0;
    undisplay_dollar();
  }
  else
    revins_scol = -1;
  p_hkmap = curwin->w_p_rl ^ p_ri; // be consistent!
}
#endif

/*
 * If 'keymodel' contains "startsel", may start selection.
 * Returns TRUE when a CTRL-O and other keys stuffed.
 */
static int ins_start_select(int c)
{
  if (km_startsel)
    switch (c)
    {
    case K_KHOME:
    case K_KEND:
    case K_PAGEUP:
    case K_KPAGEUP:
    case K_PAGEDOWN:
    case K_KPAGEDOWN:
#ifdef MACOS_X
    case K_LEFT:
    case K_RIGHT:
    case K_UP:
    case K_DOWN:
    case K_END:
    case K_HOME:
#endif
      if (!(mod_mask & MOD_MASK_SHIFT))
        break;
      /* FALLTHROUGH */
    case K_S_LEFT:
    case K_S_RIGHT:
    case K_S_UP:
    case K_S_DOWN:
    case K_S_END:
    case K_S_HOME:
      /* Start selection right away, the cursor can move with
       * CTRL-O when beyond the end of the line. */
      start_selection();

      /* Execute the key in (insert) Select mode. */
      stuffcharReadbuff(Ctrl_O);
      if (mod_mask)
      {
        char_u buf[4];

        buf[0] = K_SPECIAL;
        buf[1] = KS_MODIFIER;
        buf[2] = mod_mask;
        buf[3] = NUL;
        stuffReadbuff(buf);
      }
      stuffcharReadbuff(c);
      return TRUE;
    }
  return FALSE;
}

/*
 * <Insert> key in Insert mode: toggle insert/replace mode.
 */
static void ins_insert(int replaceState)
{
#ifdef FEAT_EVAL
  set_vim_var_string(VV_INSERTMODE,
                     (char_u *)((State & REPLACE_FLAG)
                                    ? "i"
                                    : replaceState == VREPLACE ? "v" : "r"),
                     1);
#endif
  ins_apply_autocmds(EVENT_INSERTCHANGE);
  if (State & REPLACE_FLAG)
    State = INSERT | (State & LANGMAP);
  else
    State = replaceState | (State & LANGMAP);
  AppendCharToRedobuff(K_INS);
}

/*
 * Pressed CTRL-O in Insert mode.
 */
static void ins_ctrl_o(void)
{
  if (State & VREPLACE_FLAG)
    restart_edit = 'V';
  else if (State & REPLACE_FLAG)
    restart_edit = 'R';
  else
    restart_edit = 'I';
  if (virtual_active())
    ins_at_eol = FALSE; /* cursor always keeps its column */
  else
    ins_at_eol = (gchar_cursor() == NUL);
}

/*
 * If the cursor is on an indent, ^T/^D insert/delete one
 * shiftwidth.	Otherwise ^T/^D behave like a "<<" or ">>".
 * Always round the indent to 'shiftwidth', this is compatible
 * with vi.  But vi only supports ^T and ^D after an
 * autoindent, we support it everywhere.
 */
static void ins_shift(int c, int lastc)
{
  if (stop_arrow() == FAIL)
    return;
  AppendCharToRedobuff(c);

  /*
   * 0^D and ^^D: remove all indent.
   */
  if (c == Ctrl_D && (lastc == '0' || lastc == '^') &&
      curwin->w_cursor.col > 0)
  {
    --curwin->w_cursor.col;
    (void)del_char(FALSE); /* delete the '^' or '0' */
    /* In Replace mode, restore the characters that '^' or '0' replaced. */
    if (State & REPLACE_FLAG)
      replace_pop_ins();
    if (lastc == '^')
      old_indent = get_indent(); /* remember curr. indent */
    change_indent(INDENT_SET, 0, TRUE, 0, TRUE);
  }
  else
    change_indent(c == Ctrl_D ? INDENT_DEC : INDENT_INC, 0, TRUE, 0, TRUE);

  if (did_ai && *skipwhite(ml_get_curline()) != NUL)
    did_ai = FALSE;
#ifdef FEAT_SMARTINDENT
  did_si = FALSE;
  can_si = FALSE;
  can_si_back = FALSE;
#endif
}

static void ins_del(void)
{
  int temp;

  if (stop_arrow() == FAIL)
    return;
  if (gchar_cursor() == NUL) /* delete newline */
  {
    temp = curwin->w_cursor.col;
    if (!can_bs(BS_EOL) /* only if "eol" included */
        || do_join(2, FALSE, TRUE, FALSE, FALSE) == FAIL)
      vim_beep(BO_BS);
    else
    {
      curwin->w_cursor.col = temp;
      /* Adjust orig_line_count in case more lines have been deleted than
       * have been added. That makes sure, that open_line() later
       * can access all buffer lines correctly */
      if (State & VREPLACE_FLAG && orig_line_count > curbuf->b_ml.ml_line_count)
        orig_line_count = curbuf->b_ml.ml_line_count;
    }
  }
  else if (del_char(FALSE) == FAIL) /* delete char under cursor */
    vim_beep(BO_BS);
  did_ai = FALSE;
#ifdef FEAT_SMARTINDENT
  did_si = FALSE;
  can_si = FALSE;
  can_si_back = FALSE;
#endif
  AppendCharToRedobuff(K_DEL);
}

/*
 * Delete one character for ins_bs().
 */
static void ins_bs_one(colnr_T *vcolp)
{
  dec_cursor();
  getvcol(curwin, &curwin->w_cursor, vcolp, NULL, NULL);
  if (State & REPLACE_FLAG)
  {
    /* Don't delete characters before the insert point when in
     * Replace mode */
    if (curwin->w_cursor.lnum != Insstart.lnum ||
        curwin->w_cursor.col >= Insstart.col)
      replace_do_bs(-1);
  }
  else
    (void)del_char(FALSE);
}

/*
 * Handle Backspace, delete-word and delete-line in Insert mode.
 * Return TRUE when backspace was actually used.
 */
static int ins_bs(int c, int mode, int *inserted_space_p)
{
  linenr_T lnum;
  int cc;
  int temp = 0; /* init for GCC */
  colnr_T save_col;
  colnr_T mincol;
  int did_backspace = FALSE;
  int in_indent;
  int oldState;
  int cpc[MAX_MCO]; /* composing characters */

  /*
   * can't delete anything in an empty file
   * can't backup past first character in buffer
   * can't backup past starting point unless 'backspace' > 1
   * can backup to a previous line if 'backspace' == 0
   */
  if (BUFEMPTY() ||
      (
#ifdef FEAT_RIGHTLEFT
          !revins_on &&
#endif
          ((curwin->w_cursor.lnum == 1 && curwin->w_cursor.col == 0) ||
           (!can_bs(BS_START) &&
            (arrow_used || (curwin->w_cursor.lnum == Insstart_orig.lnum &&
                            curwin->w_cursor.col <= Insstart_orig.col))) ||
           (!can_bs(BS_INDENT) && !arrow_used && ai_col > 0 &&
            curwin->w_cursor.col <= ai_col) ||
           (!can_bs(BS_EOL) && curwin->w_cursor.col == 0))))
  {
    vim_beep(BO_BS);
    return FALSE;
  }

  if (stop_arrow() == FAIL)
    return FALSE;
  in_indent = inindent(0);
#ifdef FEAT_COMMENTS
  end_comment_pending = NUL; /* After BS, don't auto-end comment */
#endif
#ifdef FEAT_RIGHTLEFT
  if (revins_on) /* put cursor after last inserted char */
    inc_cursor();
#endif

  /* Virtualedit:
   *	BACKSPACE_CHAR eats a virtual space
   *	BACKSPACE_WORD eats all coladd
   *	BACKSPACE_LINE eats all coladd and keeps going
   */
  if (curwin->w_cursor.coladd > 0)
  {
    if (mode == BACKSPACE_CHAR)
    {
      --curwin->w_cursor.coladd;
      return TRUE;
    }
    if (mode == BACKSPACE_WORD)
    {
      curwin->w_cursor.coladd = 0;
      return TRUE;
    }
    curwin->w_cursor.coladd = 0;
  }

  /*
   * Delete newline!
   */
  if (curwin->w_cursor.col == 0)
  {
    lnum = Insstart.lnum;
    if (curwin->w_cursor.lnum == lnum
#ifdef FEAT_RIGHTLEFT
        || revins_on
#endif
    )
    {
      if (u_save((linenr_T)(curwin->w_cursor.lnum - 2),
                 (linenr_T)(curwin->w_cursor.lnum + 1)) == FAIL)
        return FALSE;
      --Insstart.lnum;
      Insstart.col = (colnr_T)STRLEN(ml_get(Insstart.lnum));
    }
    /*
     * In replace mode:
     * cc < 0: NL was inserted, delete it
     * cc >= 0: NL was replaced, put original characters back
     */
    cc = -1;
    if (State & REPLACE_FLAG)
      cc = replace_pop(); /* returns -1 if NL was inserted */
    /*
     * In replace mode, in the line we started replacing, we only move the
     * cursor.
     */
    if ((State & REPLACE_FLAG) && curwin->w_cursor.lnum <= lnum)
    {
      dec_cursor();
    }
    else
    {
      if (!(State & VREPLACE_FLAG) || curwin->w_cursor.lnum > orig_line_count)
      {
        temp = gchar_cursor(); /* remember current char */
        --curwin->w_cursor.lnum;

        /* When "aw" is in 'formatoptions' we must delete the space at
         * the end of the line, otherwise the line will be broken
         * again when auto-formatting. */
        if (has_format_option(FO_AUTO) && has_format_option(FO_WHITE_PAR))
        {
          char_u *ptr = ml_get_buf(curbuf, curwin->w_cursor.lnum, TRUE);
          int len;

          len = (int)STRLEN(ptr);
          if (len > 0 && ptr[len - 1] == ' ')
            ptr[len - 1] = NUL;
        }

        (void)do_join(2, FALSE, FALSE, FALSE, FALSE);
        if (temp == NUL && gchar_cursor() != NUL)
          inc_cursor();
      }
      else
        dec_cursor();

      /*
       * In REPLACE mode we have to put back the text that was replaced
       * by the NL. On the replace stack is first a NUL-terminated
       * sequence of characters that were deleted and then the
       * characters that NL replaced.
       */
      if (State & REPLACE_FLAG)
      {
        /*
         * Do the next ins_char() in NORMAL state, to
         * prevent ins_char() from replacing characters and
         * avoiding showmatch().
         */
        oldState = State;
        State = NORMAL;
        /*
         * restore characters (blanks) deleted after cursor
         */
        while (cc > 0)
        {
          save_col = curwin->w_cursor.col;
          mb_replace_pop_ins(cc);
          curwin->w_cursor.col = save_col;
          cc = replace_pop();
        }
        /* restore the characters that NL replaced */
        replace_pop_ins();
        State = oldState;
      }
    }
    did_ai = FALSE;
  }
  else
  {
    /*
     * Delete character(s) before the cursor.
     */
#ifdef FEAT_RIGHTLEFT
    if (revins_on) /* put cursor on last inserted char */
      dec_cursor();
#endif
    mincol = 0;
    /* keep indent */
    if (mode == BACKSPACE_LINE &&
        (curbuf->b_p_ai)
#ifdef FEAT_RIGHTLEFT
        && !revins_on
#endif
    )
    {
      save_col = curwin->w_cursor.col;
      beginline(BL_WHITE);
      if (curwin->w_cursor.col < save_col)
        mincol = curwin->w_cursor.col;
      curwin->w_cursor.col = save_col;
    }

    /*
     * Handle deleting one 'shiftwidth' or 'softtabstop'.
     */
    if (mode == BACKSPACE_CHAR &&
        ((p_sta && in_indent) || ((get_sts_value() != 0
#ifdef FEAT_VARTABS
                                   || tabstop_count(curbuf->b_p_vsts_array)
#endif
                                       ) &&
                                  curwin->w_cursor.col > 0 &&
                                  (*(ml_get_cursor() - 1) == TAB ||
                                   (*(ml_get_cursor() - 1) == ' ' &&
                                    (!*inserted_space_p || arrow_used))))))
    {
      int ts;
      colnr_T vcol;
      colnr_T want_vcol;
      colnr_T start_vcol;

      *inserted_space_p = FALSE;
      /* Compute the virtual column where we want to be.  Since
       * 'showbreak' may get in the way, need to get the last column of
       * the previous character. */
      getvcol(curwin, &curwin->w_cursor, &vcol, NULL, NULL);
      start_vcol = vcol;
      dec_cursor();
      getvcol(curwin, &curwin->w_cursor, NULL, NULL, &want_vcol);
      inc_cursor();
#ifdef FEAT_VARTABS
      if (p_sta && in_indent)
      {
        ts = (int)get_sw_value(curbuf);
        want_vcol = (want_vcol / ts) * ts;
      }
      else
        want_vcol =
            tabstop_start(want_vcol, get_sts_value(), curbuf->b_p_vsts_array);
#else
      if (p_sta && in_indent)
        ts = (int)get_sw_value(curbuf);
      else
        ts = (int)get_sts_value();
      want_vcol = (want_vcol / ts) * ts;
#endif

      /* delete characters until we are at or before want_vcol */
      while (vcol > want_vcol && (cc = *(ml_get_cursor() - 1), VIM_ISWHITE(cc)))
        ins_bs_one(&vcol);

      /* insert extra spaces until we are at want_vcol */
      while (vcol < want_vcol)
      {
        /* Remember the first char we inserted */
        if (curwin->w_cursor.lnum == Insstart_orig.lnum &&
            curwin->w_cursor.col < Insstart_orig.col)
          Insstart_orig.col = curwin->w_cursor.col;

        if (State & VREPLACE_FLAG)
          ins_char(' ');
        else
        {
          ins_str((char_u *)" ");
          if ((State & REPLACE_FLAG))
            replace_push(NUL);
        }
        getvcol(curwin, &curwin->w_cursor, &vcol, NULL, NULL);
      }

      /* If we are now back where we started delete one character.  Can
       * happen when using 'sts' and 'linebreak'. */
      if (vcol >= start_vcol)
        ins_bs_one(&vcol);
    }

    /*
     * Delete upto starting point, start of line or previous word.
     */
    else
    {
      int cclass = 0, prev_cclass = 0;

      if (has_mbyte)
        cclass = mb_get_class(ml_get_cursor());
      do
      {
#ifdef FEAT_RIGHTLEFT
        if (!revins_on) /* put cursor on char to be deleted */
#endif
          dec_cursor();

        cc = gchar_cursor();
        /* look multi-byte character class */
        if (has_mbyte)
        {
          prev_cclass = cclass;
          cclass = mb_get_class(ml_get_cursor());
        }

        /* start of word? */
        if (mode == BACKSPACE_WORD && !vim_isspace(cc))
        {
          mode = BACKSPACE_WORD_NOT_SPACE;
          temp = vim_iswordc(cc);
        }
        /* end of word? */
        else if (mode == BACKSPACE_WORD_NOT_SPACE &&
                 ((vim_isspace(cc) || vim_iswordc(cc) != temp) ||
                  prev_cclass != cclass))
        {
#ifdef FEAT_RIGHTLEFT
          if (!revins_on)
#endif
            inc_cursor();
#ifdef FEAT_RIGHTLEFT
          else if (State & REPLACE_FLAG)
            dec_cursor();
#endif
          break;
        }
        if (State & REPLACE_FLAG)
          replace_do_bs(-1);
        else
        {
          if (enc_utf8 && p_deco)
            (void)utfc_ptr2char(ml_get_cursor(), cpc);
          (void)del_char(FALSE);
          /*
           * If there are combining characters and 'delcombine' is set
           * move the cursor back.  Don't back up before the base
           * character.
           */
          if (enc_utf8 && p_deco && cpc[0] != NUL)
            inc_cursor();
#ifdef FEAT_RIGHTLEFT
          if (revins_chars)
          {
            revins_chars--;
            revins_legal++;
          }
          if (revins_on && gchar_cursor() == NUL)
            break;
#endif
        }
        /* Just a single backspace?: */
        if (mode == BACKSPACE_CHAR)
          break;
      } while (
#ifdef FEAT_RIGHTLEFT
          revins_on ||
#endif
          (curwin->w_cursor.col > mincol &&
           (curwin->w_cursor.lnum != Insstart_orig.lnum ||
            curwin->w_cursor.col != Insstart_orig.col)));
    }
    did_backspace = TRUE;
  }
#ifdef FEAT_SMARTINDENT
  did_si = FALSE;
  can_si = FALSE;
  can_si_back = FALSE;
#endif
  if (curwin->w_cursor.col <= 1)
    did_ai = FALSE;
  /*
   * It's a little strange to put backspaces into the redo
   * buffer, but it makes auto-indent a lot easier to deal
   * with.
   */
  AppendCharToRedobuff(c);

  /* If deleted before the insertion point, adjust it */
  if (curwin->w_cursor.lnum == Insstart_orig.lnum &&
      curwin->w_cursor.col < Insstart_orig.col)
    Insstart_orig.col = curwin->w_cursor.col;

  /* vi behaviour: the cursor moves backward but the character that
   *		     was there remains visible
   * Vim behaviour: the cursor moves backward and the character that
   *		      was there is erased from the screen.
   * We can emulate the vi behaviour by pretending there is a dollar
   * displayed even when there isn't.
   *  --pkv Sun Jan 19 01:56:40 EST 2003 */
  if (vim_strchr(p_cpo, CPO_BACKSPACE) != NULL && dollar_vcol == -1)
    dollar_vcol = curwin->w_virtcol;

#ifdef FEAT_FOLDING
  /* When deleting a char the cursor line must never be in a closed fold.
   * E.g., when 'foldmethod' is indent and deleting the first non-white
   * char before a Tab. */
  if (did_backspace)
    foldOpenCursor();
#endif

  return did_backspace;
}

/*
 * Handle receiving P_PS: start paste mode.  Inserts the following text up to
 * P_PE literally.
 * When "drop" is TRUE then consume the text and drop it.
 */
int bracketed_paste(paste_mode_T mode, int drop, garray_T *gap)
{
  int c;
  char_u buf[NUMBUFLEN + MB_MAXBYTES];
  int idx = 0;
  char_u *end = find_termcode((char_u *)"PE");
  int ret_char = -1;
  int save_allow_keys = allow_keys;
  int save_paste = p_paste;

  /* If the end code is too long we can't detect it, read everything. */
  if (STRLEN(end) >= NUMBUFLEN)
    end = NULL;
  ++no_mapping;
  allow_keys = 0;
  if (!p_paste)
    // Also have the side effects of setting 'paste' to make it work much
    // faster.
    set_option_value((char_u *)"paste", TRUE, NULL, 0);

  for (;;)
  {
    // When the end is not defined read everything there is.
    if (end == NULL && vpeekc() == NUL)
      break;
    do
      c = vgetc();
    while (c == K_IGNORE || c == K_VER_SCROLLBAR || c == K_HOR_SCROLLBAR);
    if (c == NUL || got_int)
      // When CTRL-C was encountered the typeahead will be flushed and we
      // won't get the end sequence.
      break;

    if (has_mbyte)
      idx += (*mb_char2bytes)(c, buf + idx);
    else
      buf[idx++] = c;
    buf[idx] = NUL;
    if (end != NULL && STRNCMP(buf, end, idx) == 0)
    {
      if (end[idx] == NUL)
        break; /* Found the end of paste code. */
      continue;
    }
    if (!drop)
    {
      switch (mode)
      {
      case PASTE_CMDLINE:
        put_on_cmdline(buf, idx, TRUE);
        break;

      case PASTE_EX:
        if (gap != NULL && ga_grow(gap, idx) == OK)
        {
          mch_memmove((char *)gap->ga_data + gap->ga_len, buf, (size_t)idx);
          gap->ga_len += idx;
        }
        break;

      case PASTE_INSERT:
        if (stop_arrow() == OK)
        {
          c = buf[0];
          if (idx == 1 && (c == CAR || c == K_KENTER || c == NL))
            ins_eol(c);
          else
          {
            ins_char_bytes(buf, idx);
            AppendToRedobuffLit(buf, idx);
          }
        }
        break;

      case PASTE_ONE_CHAR:
        if (ret_char == -1)
        {
          if (has_mbyte)
            ret_char = (*mb_ptr2char)(buf);
          else
            ret_char = buf[0];
        }
        break;
      }
    }
    idx = 0;
  }

  --no_mapping;
  allow_keys = save_allow_keys;
  if (!save_paste)
    set_option_value((char_u *)"paste", FALSE, NULL, 0);

  return ret_char;
}

static void ins_left(void)
{
  pos_T tpos;
  int end_change = dont_sync_undo == FALSE; // end undoable change

#ifdef FEAT_FOLDING
  if ((fdo_flags & FDO_HOR) && KeyTyped)
    foldOpenCursor();
#endif
  undisplay_dollar();
  tpos = curwin->w_cursor;
  if (oneleft() == OK)
  {
    {
      start_arrow_with_change(&tpos, end_change);
      if (!end_change)
        AppendCharToRedobuff(K_LEFT);
    }
#ifdef FEAT_RIGHTLEFT
    /* If exit reversed string, position is fixed */
    if (revins_scol != -1 && (int)curwin->w_cursor.col >= revins_scol)
      revins_legal++;
    revins_chars++;
#endif
  }

  /*
   * if 'whichwrap' set for cursor in insert mode may go to
   * previous line
   */
  else if (vim_strchr(p_ww, '[') != NULL && curwin->w_cursor.lnum > 1)
  {
    /* always break undo when moving upwards/downwards, else undo may break */
    start_arrow(&tpos);
    --(curwin->w_cursor.lnum);
    coladvance((colnr_T)MAXCOL);
    curwin->w_set_curswant = TRUE; /* so we stay at the end */
  }
  else
    vim_beep(BO_CRSR);
  dont_sync_undo = FALSE;
}

static void ins_home(int c)
{
  pos_T tpos;

#ifdef FEAT_FOLDING
  if ((fdo_flags & FDO_HOR) && KeyTyped)
    foldOpenCursor();
#endif
  undisplay_dollar();
  tpos = curwin->w_cursor;
  if (c == K_C_HOME)
    curwin->w_cursor.lnum = 1;
  curwin->w_cursor.col = 0;
  curwin->w_cursor.coladd = 0;
  curwin->w_curswant = 0;
  start_arrow(&tpos);
}

static void ins_end(int c)
{
  pos_T tpos;

#ifdef FEAT_FOLDING
  if ((fdo_flags & FDO_HOR) && KeyTyped)
    foldOpenCursor();
#endif
  undisplay_dollar();
  tpos = curwin->w_cursor;
  if (c == K_C_END)
    curwin->w_cursor.lnum = curbuf->b_ml.ml_line_count;
  coladvance((colnr_T)MAXCOL);
  curwin->w_curswant = MAXCOL;

  start_arrow(&tpos);
}

static void ins_s_left()
{
  int end_change = dont_sync_undo == FALSE; // end undoable change
#ifdef FEAT_FOLDING
  if ((fdo_flags & FDO_HOR) && KeyTyped)
    foldOpenCursor();
#endif
  undisplay_dollar();
  if (curwin->w_cursor.lnum > 1 || curwin->w_cursor.col > 0)
  {
    start_arrow_with_change(&curwin->w_cursor, end_change);
    if (!end_change)
      AppendCharToRedobuff(K_S_LEFT);
    (void)bck_word(1L, FALSE, FALSE);
    curwin->w_set_curswant = TRUE;
  }
  else
    vim_beep(BO_CRSR);
  dont_sync_undo = FALSE;
}

static void ins_right(void)
{
  int end_change = dont_sync_undo == FALSE; // end undoable change

#ifdef FEAT_FOLDING
  if ((fdo_flags & FDO_HOR) && KeyTyped)
    foldOpenCursor();
#endif
  undisplay_dollar();
  if (gchar_cursor() != NUL || virtual_active())
  {
    start_arrow_with_change(&curwin->w_cursor, end_change);
    if (!end_change)
      AppendCharToRedobuff(K_RIGHT);
    curwin->w_set_curswant = TRUE;
    if (virtual_active())
      oneright();
    else
    {
      if (has_mbyte)
        curwin->w_cursor.col += (*mb_ptr2len)(ml_get_cursor());
      else
        ++curwin->w_cursor.col;
    }

#ifdef FEAT_RIGHTLEFT
    revins_legal++;
    if (revins_chars)
      revins_chars--;
#endif
  }
  /* if 'whichwrap' set for cursor in insert mode, may move the
   * cursor to the next line */
  else if (vim_strchr(p_ww, ']') != NULL &&
           curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count)
  {
    start_arrow(&curwin->w_cursor);
    curwin->w_set_curswant = TRUE;
    ++curwin->w_cursor.lnum;
    curwin->w_cursor.col = 0;
  }
  else
    vim_beep(BO_CRSR);
  dont_sync_undo = FALSE;
}

static void ins_s_right()
{
  int end_change = dont_sync_undo == FALSE; // end undoable change
#ifdef FEAT_FOLDING
  if ((fdo_flags & FDO_HOR) && KeyTyped)
    foldOpenCursor();
#endif
  undisplay_dollar();
  if (curwin->w_cursor.lnum < curbuf->b_ml.ml_line_count ||
      gchar_cursor() != NUL)
  {
    start_arrow_with_change(&curwin->w_cursor, end_change);
    if (!end_change)
      AppendCharToRedobuff(K_S_RIGHT);
    (void)fwd_word(1L, FALSE, 0);
    curwin->w_set_curswant = TRUE;
  }
  else
    vim_beep(BO_CRSR);
  dont_sync_undo = FALSE;
}

static void ins_up(int startcol) /* when TRUE move to Insstart.col */
{
  pos_T tpos;
  linenr_T old_topline = curwin->w_topline;
#ifdef FEAT_DIFF
  int old_topfill = curwin->w_topfill;
#endif

  undisplay_dollar();
  tpos = curwin->w_cursor;
  if (cursor_up(1L, TRUE) == OK)
  {
    if (startcol)
      coladvance(getvcol_nolist(&Insstart));
    if (old_topline != curwin->w_topline
#ifdef FEAT_DIFF
        || old_topfill != curwin->w_topfill
#endif
    )
      redraw_later(VALID);
    start_arrow(&tpos);
  }
  else
    vim_beep(BO_CRSR);
}

static void ins_pageup(void)
{
  pos_T tpos;

  undisplay_dollar();

  if (mod_mask & MOD_MASK_CTRL)
  {
    /* <C-PageUp>: tab page back */
    if (first_tabpage->tp_next != NULL)
    {
      start_arrow(&curwin->w_cursor);
      goto_tabpage(-1);
    }
    return;
  }

  tpos = curwin->w_cursor;
  if (onepage(BACKWARD, 1L) == OK)
  {
    start_arrow(&tpos);
  }
  else
    vim_beep(BO_CRSR);
}

static void ins_down(int startcol) /* when TRUE move to Insstart.col */
{
  pos_T tpos;
  linenr_T old_topline = curwin->w_topline;
#ifdef FEAT_DIFF
  int old_topfill = curwin->w_topfill;
#endif

  undisplay_dollar();
  tpos = curwin->w_cursor;
  if (cursor_down(1L, TRUE) == OK)
  {
    if (startcol)
      coladvance(getvcol_nolist(&Insstart));
    if (old_topline != curwin->w_topline
#ifdef FEAT_DIFF
        || old_topfill != curwin->w_topfill
#endif
    )
      redraw_later(VALID);
    start_arrow(&tpos);
  }
  else
    vim_beep(BO_CRSR);
}

static void ins_pagedown(void)
{
  pos_T tpos;

  undisplay_dollar();

  if (mod_mask & MOD_MASK_CTRL)
  {
    /* <C-PageDown>: tab page forward */
    if (first_tabpage->tp_next != NULL)
    {
      start_arrow(&curwin->w_cursor);
      goto_tabpage(0);
    }
    return;
  }

  tpos = curwin->w_cursor;
  if (onepage(FORWARD, 1L) == OK)
  {
    start_arrow(&tpos);
  }
  else
    vim_beep(BO_CRSR);
}

/*
 * Handle TAB in Insert or Replace mode.
 * Return TRUE when the TAB needs to be inserted like a normal character.
 */
static int ins_tab(void)
{
  int ind;
  int i;
  int temp;

  if (Insstart_blank_vcol == MAXCOL && curwin->w_cursor.lnum == Insstart.lnum)
    Insstart_blank_vcol = get_nolist_virtcol();
  if (echeck_abbr(TAB + ABBR_OFF))
    return FALSE;

  ind = inindent(0);

  /*
   * When nothing special, insert TAB like a normal character.
   */
  if (!curbuf->b_p_et
#ifdef FEAT_VARTABS
      && !(p_sta &&
           ind
           /* These five lines mean 'tabstop' != 'shiftwidth' */
           && ((tabstop_count(curbuf->b_p_vts_array) > 1) ||
               (tabstop_count(curbuf->b_p_vts_array) == 1 &&
                tabstop_first(curbuf->b_p_vts_array) != get_sw_value(curbuf)) ||
               (tabstop_count(curbuf->b_p_vts_array) == 0 &&
                curbuf->b_p_ts != get_sw_value(curbuf)))) &&
      tabstop_count(curbuf->b_p_vsts_array) == 0
#else
      && !(p_sta && ind && curbuf->b_p_ts != get_sw_value(curbuf))
#endif
      && get_sts_value() == 0)
    return TRUE;

  if (stop_arrow() == FAIL)
    return TRUE;

  did_ai = FALSE;
#ifdef FEAT_SMARTINDENT
  did_si = FALSE;
  can_si = FALSE;
  can_si_back = FALSE;
#endif
  AppendToRedobuff((char_u *)"\t");

#ifdef FEAT_VARTABS
  if (p_sta && ind) /* insert tab in indent, use 'shiftwidth' */
  {
    temp = (int)get_sw_value(curbuf);
    temp -= get_nolist_virtcol() % temp;
  }
  else if (tabstop_count(curbuf->b_p_vsts_array) > 0 || curbuf->b_p_sts != 0)
    /* use 'softtabstop' when set */
    temp = tabstop_padding(get_nolist_virtcol(), get_sts_value(),
                           curbuf->b_p_vsts_array);
  else /* otherwise use 'tabstop' */
    temp = tabstop_padding(get_nolist_virtcol(), curbuf->b_p_ts,
                           curbuf->b_p_vts_array);
#else
  if (p_sta && ind) /* insert tab in indent, use 'shiftwidth' */
    temp = (int)get_sw_value(curbuf);
  else if (curbuf->b_p_sts != 0) /* use 'softtabstop' when set */
    temp = (int)get_sts_value();
  else /* otherwise use 'tabstop' */
    temp = (int)curbuf->b_p_ts;
  temp -= get_nolist_virtcol() % temp;
#endif

  /*
   * Insert the first space with ins_char().	It will delete one char in
   * replace mode.  Insert the rest with ins_str(); it will not delete any
   * chars.  For VREPLACE mode, we use ins_char() for all characters.
   */
  ins_char(' ');
  while (--temp > 0)
  {
    if (State & VREPLACE_FLAG)
      ins_char(' ');
    else
    {
      ins_str((char_u *)" ");
      if (State & REPLACE_FLAG) /* no char replaced */
        replace_push(NUL);
    }
  }

  /*
   * When 'expandtab' not set: Replace spaces by TABs where possible.
   */
#ifdef FEAT_VARTABS
  if (!curbuf->b_p_et && (tabstop_count(curbuf->b_p_vsts_array) > 0 ||
                          get_sts_value() > 0 || (p_sta && ind)))
#else
  if (!curbuf->b_p_et && (get_sts_value() || (p_sta && ind)))
#endif
  {
    char_u *ptr;
    char_u *saved_line = NULL; /* init for GCC */
    pos_T pos;
    pos_T fpos;
    pos_T *cursor;
    colnr_T want_vcol, vcol;
    int change_col = -1;
    int save_list = curwin->w_p_list;

    /*
     * Get the current line.  For VREPLACE mode, don't make real changes
     * yet, just work on a copy of the line.
     */
    if (State & VREPLACE_FLAG)
    {
      pos = curwin->w_cursor;
      cursor = &pos;
      saved_line = vim_strsave(ml_get_curline());
      if (saved_line == NULL)
        return FALSE;
      ptr = saved_line + pos.col;
    }
    else
    {
      ptr = ml_get_cursor();
      cursor = &curwin->w_cursor;
    }

    /* When 'L' is not in 'cpoptions' a tab always takes up 'ts' spaces. */
    if (vim_strchr(p_cpo, CPO_LISTWM) == NULL)
      curwin->w_p_list = FALSE;

    /* Find first white before the cursor */
    fpos = curwin->w_cursor;
    while (fpos.col > 0 && VIM_ISWHITE(ptr[-1]))
    {
      --fpos.col;
      --ptr;
    }

    /* In Replace mode, don't change characters before the insert point. */
    if ((State & REPLACE_FLAG) && fpos.lnum == Insstart.lnum &&
        fpos.col < Insstart.col)
    {
      ptr += Insstart.col - fpos.col;
      fpos.col = Insstart.col;
    }

    /* compute virtual column numbers of first white and cursor */
    getvcol(curwin, &fpos, &vcol, NULL, NULL);
    getvcol(curwin, cursor, &want_vcol, NULL, NULL);

    /* Use as many TABs as possible.  Beware of 'breakindent', 'showbreak'
     * and 'linebreak' adding extra virtual columns. */
    while (VIM_ISWHITE(*ptr))
    {
      i = lbr_chartabsize(NULL, (char_u *)"\t", vcol);
      if (vcol + i > want_vcol)
        break;
      if (*ptr != TAB)
      {
        *ptr = TAB;
        if (change_col < 0)
        {
          change_col = fpos.col; /* Column of first change */
          /* May have to adjust Insstart */
          if (fpos.lnum == Insstart.lnum && fpos.col < Insstart.col)
            Insstart.col = fpos.col;
        }
      }
      ++fpos.col;
      ++ptr;
      vcol += i;
    }

    if (change_col >= 0)
    {
      int repl_off = 0;
      char_u *line = ptr;

      /* Skip over the spaces we need. */
      while (vcol < want_vcol && *ptr == ' ')
      {
        vcol += lbr_chartabsize(line, ptr, vcol);
        ++ptr;
        ++repl_off;
      }
      if (vcol > want_vcol)
      {
        /* Must have a char with 'showbreak' just before it. */
        --ptr;
        --repl_off;
      }
      fpos.col += repl_off;

      /* Delete following spaces. */
      i = cursor->col - fpos.col;
      if (i > 0)
      {
        STRMOVE(ptr, ptr + i);
        /* correct replace stack. */
        if ((State & REPLACE_FLAG) && !(State & VREPLACE_FLAG))
          for (temp = i; --temp >= 0;)
            replace_join(repl_off);
      }
      cursor->col -= i;

      /*
       * In VREPLACE mode, we haven't changed anything yet.  Do it now by
       * backspacing over the changed spacing and then inserting the new
       * spacing.
       */
      if (State & VREPLACE_FLAG)
      {
        /* Backspace from real cursor to change_col */
        backspace_until_column(change_col);

        /* Insert each char in saved_line from changed_col to
         * ptr-cursor */
        ins_bytes_len(saved_line + change_col, cursor->col - change_col);
      }
    }

    if (State & VREPLACE_FLAG)
      vim_free(saved_line);
    curwin->w_p_list = save_list;
  }

  return FALSE;
}

/*
 * Handle CR or NL in insert mode.
 * Return FAIL when out of memory or can't undo.
 */
int ins_eol(int c)
{
  int i;

  if (echeck_abbr(c + ABBR_OFF))
    return OK;
  if (stop_arrow() == FAIL)
    return FAIL;
  undisplay_dollar();

  /*
   * Strange Vi behaviour: In Replace mode, typing a NL will not delete the
   * character under the cursor.  Only push a NUL on the replace stack,
   * nothing to put back when the NL is deleted.
   */
  if ((State & REPLACE_FLAG) && !(State & VREPLACE_FLAG))
    replace_push(NUL);

  /*
   * In VREPLACE mode, a NL replaces the rest of the line, and starts
   * replacing the next line, so we push all of the characters left on the
   * line onto the replace stack.  This is not done here though, it is done
   * in open_line().
   */

  /* Put cursor on NUL if on the last char and coladd is 1 (happens after
   * CTRL-O). */
  if (virtual_active() && curwin->w_cursor.coladd > 0)
    coladvance(getviscol());

#ifdef FEAT_RIGHTLEFT
  /* NL in reverse insert will always start in the end of
   * current line. */
  if (revins_on)
    curwin->w_cursor.col += (colnr_T)STRLEN(ml_get_cursor());
#endif

  AppendToRedobuff(NL_STR);
  i = open_line(FORWARD,
#ifdef FEAT_COMMENTS
                has_format_option(FO_RET_COMS) ? OPENLINE_DO_COM :
#endif
                                               0,
                old_indent);
  old_indent = 0;
#ifdef FEAT_FOLDING
  /* When inserting a line the cursor line must never be in a closed fold. */
  foldOpenCursor();
#endif

  return i;
}

#ifdef FEAT_DIGRAPHS
/*
 * Handle digraph in insert mode.
 * Returns character still to be inserted, or NUL when nothing remaining to be
 * done.
 */
static int ins_digraph(void)
{
  int c;
  int cc;
  int did_putchar = FALSE;

  pc_status = PC_STATUS_UNSET;
  if (redrawing() && !char_avail())
  {
    /* may need to redraw when no more chars available now */
    ins_redraw(FALSE);

    edit_putchar('?', TRUE);
    did_putchar = TRUE;
  }

  /* don't map the digraph chars. This also prevents the
   * mode message to be deleted when ESC is hit */
  ++no_mapping;
  ++allow_keys;
  c = plain_vgetc();
  --no_mapping;
  --allow_keys;
  if (did_putchar)
    /* when the line fits in 'columns' the '?' is at the start of the next
     * line and will not be removed by the redraw */
    edit_unputchar();

  if (IS_SPECIAL(c) || mod_mask) /* special key */
  {
    insert_special(c, TRUE, FALSE);
    return NUL;
  }
  if (c != ESC)
  {
    did_putchar = FALSE;
    if (redrawing() && !char_avail())
    {
      /* may need to redraw when no more chars available now */
      ins_redraw(FALSE);

      if (char2cells(c) == 1)
      {
        ins_redraw(FALSE);
        edit_putchar(c, TRUE);
        did_putchar = TRUE;
      }
    }
    ++no_mapping;
    ++allow_keys;
    cc = plain_vgetc();
    --no_mapping;
    --allow_keys;
    if (did_putchar)
      /* when the line fits in 'columns' the '?' is at the start of the
       * next line and will not be removed by a redraw */
      edit_unputchar();
    if (cc != ESC)
    {
      AppendToRedobuff((char_u *)CTRL_V_STR);
      c = getdigraph(c, cc, TRUE);
      return c;
    }
  }
  return NUL;
}
#endif

/*
 * Handle CTRL-E and CTRL-Y in Insert mode: copy char from other line.
 * Returns the char to be inserted, or NUL if none found.
 */
int ins_copychar(linenr_T lnum)
{
  int c;
  int temp;
  char_u *ptr, *prev_ptr;
  char_u *line;

  if (lnum < 1 || lnum > curbuf->b_ml.ml_line_count)
  {
    vim_beep(BO_COPY);
    return NUL;
  }

  /* try to advance to the cursor column */
  temp = 0;
  line = ptr = ml_get(lnum);
  prev_ptr = ptr;
  validate_virtcol();
  while ((colnr_T)temp < curwin->w_virtcol && *ptr != NUL)
  {
    prev_ptr = ptr;
    temp += lbr_chartabsize_adv(line, &ptr, (colnr_T)temp);
  }
  if ((colnr_T)temp > curwin->w_virtcol)
    ptr = prev_ptr;

  c = (*mb_ptr2char)(ptr);
  if (c == NUL)
    vim_beep(BO_COPY);
  return c;
}

/*
 * CTRL-Y or CTRL-E typed in Insert mode.
 */
static int ins_ctrl_ey(int tc)
{
  int c = tc;

  c = ins_copychar(curwin->w_cursor.lnum + (c == Ctrl_Y ? -1 : 1));
  if (c != NUL)
  {
    long tw_save;

    /* The character must be taken literally, insert like it
       * was typed after a CTRL-V, and pretend 'textwidth'
       * wasn't set.  Digits, 'o' and 'x' are special after a
       * CTRL-V, don't use it for these. */
    if (c < 256 && !isalnum(c))
      AppendToRedobuff((char_u *)CTRL_V_STR); /* CTRL-V */
    tw_save = curbuf->b_p_tw;
    curbuf->b_p_tw = -1;
    insert_special(c, TRUE, FALSE);
    curbuf->b_p_tw = tw_save;
#ifdef FEAT_RIGHTLEFT
    revins_chars++;
    revins_legal++;
#endif
    c = Ctrl_V; /* pretend CTRL-V is last character */
    auto_format(FALSE, TRUE);
  }
  return c;
}

#ifdef FEAT_SMARTINDENT
/*
 * Try to do some very smart auto-indenting.
 * Used when inserting a "normal" character.
 */
static void ins_try_si(int c)
{
  pos_T *pos, old_pos;
  char_u *ptr;
  int i;
  int temp;

  /*
   * do some very smart indenting when entering '{' or '}'
   */
  if (((did_si || can_si_back) && c == '{') || (can_si && c == '}'))
  {
    /*
     * for '}' set indent equal to indent of line containing matching '{'
     */
    if (c == '}' && (pos = findmatch(NULL, '{')) != NULL)
    {
      old_pos = curwin->w_cursor;
      /*
       * If the matching '{' has a ')' immediately before it (ignoring
       * white-space), then line up with the start of the line
       * containing the matching '(' if there is one.  This handles the
       * case where an "if (..\n..) {" statement continues over multiple
       * lines -- webb
       */
      ptr = ml_get(pos->lnum);
      i = pos->col;
      if (i > 0) /* skip blanks before '{' */
        while (--i > 0 && VIM_ISWHITE(ptr[i]))
          ;
      curwin->w_cursor.lnum = pos->lnum;
      curwin->w_cursor.col = i;
      if (ptr[i] == ')' && (pos = findmatch(NULL, '(')) != NULL)
        curwin->w_cursor = *pos;
      i = get_indent();
      curwin->w_cursor = old_pos;
      if (State & VREPLACE_FLAG)
        change_indent(INDENT_SET, i, FALSE, NUL, TRUE);
      else
        (void)set_indent(i, SIN_CHANGED);
    }
    else if (curwin->w_cursor.col > 0)
    {
      /*
       * when inserting '{' after "O" reduce indent, but not
       * more than indent of previous line
       */
      temp = TRUE;
      if (c == '{' && can_si_back && curwin->w_cursor.lnum > 1)
      {
        old_pos = curwin->w_cursor;
        i = get_indent();
        while (curwin->w_cursor.lnum > 1)
        {
          ptr = skipwhite(ml_get(--(curwin->w_cursor.lnum)));

          /* ignore empty lines and lines starting with '#'. */
          if (*ptr != '#' && *ptr != NUL)
            break;
        }
        if (get_indent() >= i)
          temp = FALSE;
        curwin->w_cursor = old_pos;
      }
      if (temp)
        shift_line(TRUE, FALSE, 1, TRUE);
    }
  }

  /*
   * set indent of '#' always to 0
   */
  if (curwin->w_cursor.col > 0 && can_si && c == '#')
  {
    /* remember current indent for next line */
    old_indent = get_indent();
    (void)set_indent(0, SIN_CHANGED);
  }

  /* Adjust ai_col, the char at this position can be deleted. */
  if (ai_col > curwin->w_cursor.col)
    ai_col = curwin->w_cursor.col;
}
#endif

/*
 * Get the value that w_virtcol would have when 'list' is off.
 * Unless 'cpo' contains the 'L' flag.
 */
colnr_T get_nolist_virtcol(void)
{
  // check validity of cursor in current buffer
  if (curwin->w_buffer == NULL || curwin->w_buffer->b_ml.ml_mfp == NULL ||
      curwin->w_cursor.lnum > curwin->w_buffer->b_ml.ml_line_count)
    return 0;
  if (curwin->w_p_list && vim_strchr(p_cpo, CPO_LISTWM) == NULL)
    return getvcol_nolist(&curwin->w_cursor);
  validate_virtcol();
  return curwin->w_virtcol;
}

#if defined(FEAT_EVAL)
/*
 * Handle the InsertCharPre autocommand.
 * "c" is the character that was typed.
 * Return a pointer to allocated memory with the replacement string.
 * Return NULL to continue inserting "c".
 */
static char_u *do_insert_char_pre(int c)
{
  char_u *res;
  char_u buf[MB_MAXBYTES + 1];
  int save_State = State;

  /* Return quickly when there is nothing to do. */
  if (!has_insertcharpre())
    return NULL;

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

  /* Lock the text to avoid weird things from happening. */
  ++textlock;
  set_vim_var_string(VV_CHAR, buf, -1); /* set v:char */

  res = NULL;
  if (ins_apply_autocmds(EVENT_INSERTCHARPRE))
  {
    /* Get the value of v:char.  It may be empty or more than one
     * character.  Only use it when changed, otherwise continue with the
     * original character to avoid breaking autoindent. */
    if (STRCMP(buf, get_vim_var_str(VV_CHAR)) != 0)
      res = vim_strsave(get_vim_var_str(VV_CHAR));
  }

  set_vim_var_string(VV_CHAR, NULL, -1); /* clear v:char */
  --textlock;

  // Restore the State, it may have been changed.
  State = save_State;

  return res;
}
#endif

/*
 * Trigger "event" and take care of fixing undo.
 */
int ins_apply_autocmds(event_T event)
{
  varnumber_T tick = CHANGEDTICK(curbuf);
  int r;

  r = apply_autocmds(event, NULL, NULL, FALSE, curbuf);

  // If u_savesub() was called then we are not prepared to start
  // a new line.  Call u_save() with no contents to fix that.
  if (tick != CHANGEDTICK(curbuf))
    u_save(curwin->w_cursor.lnum, (linenr_T)(curwin->w_cursor.lnum + 1));

  return r;
}
