Exemplo n.º 1
0
/* Take the word before point (or Vabbrev_start_location, if non-nil),
   and look it up in OBARRAY, and return the symbol (or zero).  This
   used to be the default method of searching, with the obvious
   limitation that the abbrevs may consist only of word characters.
   It is an order of magnitude faster than the proper abbrev_match(),
   but then again, vi is an order of magnitude faster than Emacs.

   This speed difference should be unnoticeable, though.  I have tested
   the degenerated cases of thousands of abbrevs being defined, and
   abbrev_match() was still fast enough for normal operation.  */
static Lisp_Symbol *abbrev_oblookup(struct buffer *buf, Lisp_Object obarray)
{
	Bufpos wordstart, wordend;
	Bufbyte *word, *p;
	Bytecount idx;
	Lisp_Object lookup;

	CHECK_VECTOR(obarray);

	if (!NILP(Vabbrev_start_location)) {
		wordstart = get_buffer_pos_char(buf, Vabbrev_start_location,
						GB_COERCE_RANGE);
		Vabbrev_start_location = Qnil;
#if 0
		/* Previously, abbrev-prefix-mark crockishly inserted a dash to
		   indicate the abbrev start point.  It now uses an extent with
		   a begin glyph so there's no dash to remove.  */
		if (wordstart != BUF_ZV(buf)
		    && BUF_FETCH_CHAR(buf, wordstart) == '-') {
			buffer_delete_range(buf, wordstart, wordstart + 1, 0);
		}
#endif
		wordend = BUF_PT(buf);
	} else {
		Bufpos point = BUF_PT(buf);

		wordstart = scan_words(buf, point, -1);
		if (!wordstart)
			return 0;

		wordend = scan_words(buf, wordstart, 1);
		if (!wordend)
			return 0;
		if (wordend > BUF_ZV(buf))
			wordend = BUF_ZV(buf);
		if (wordend > point)
			wordend = point;
		/* Unlike the original function, we allow expansion only after
		   the abbrev, not preceded by a number of spaces.  This is
		   because of consistency with abbrev_match. */
		if (wordend < point)
			return 0;
	}

	if (wordend <= wordstart)
		return 0;

	p = word = (Bufbyte *) alloca(MAX_EMCHAR_LEN * (wordend - wordstart));
	for (idx = wordstart; idx < wordend; idx++) {
		Emchar c = BUF_FETCH_CHAR(buf, idx);
		if (UPPERCASEP(buf, c))
			c = DOWNCASE(buf, c);
		p += set_charptr_emchar(p, c);
	}
	lookup = oblookup(obarray, word, p - word);
	if (SYMBOLP(lookup) && !NILP(symbol_value(XSYMBOL(lookup))))
		return XSYMBOL(lookup);
	else
		return NULL;
}
Exemplo n.º 2
0
static Bufpos
end_of_defun (struct buffer *buf, Bufpos pt)
{
  Lisp_Object retval = scan_lists (buf, pt, 1, 0, 0, 1);
  if (NILP (retval))
    return BUF_ZV (buf);
  else
    return XINT (retval);
}
Exemplo n.º 3
0
int
update_window_fringes (struct window *w, int keep_current_p)
{
  struct glyph_row *row, *cur = 0;
  int yb = window_text_bottom_y (w);
  int rn, nrows = w->current_matrix->nrows;
  int y;
  int redraw_p = 0;
  Lisp_Object boundary_top = Qnil, boundary_bot = Qnil;
  Lisp_Object arrow_top = Qnil, arrow_bot = Qnil;
  Lisp_Object empty_pos;
  Lisp_Object ind = Qnil;
#define MAX_BITMAP_CACHE (8*4)
  int bitmap_cache[MAX_BITMAP_CACHE];
  int top_ind_rn, bot_ind_rn;
  int top_ind_min_y, bot_ind_max_y;

  /* top_ind_rn is set to a nonnegative value whenver
     row->indicate_bob_p is set, so it's OK that top_row_ends_at_zv_p
     is not initialized here.  Similarly for bot_ind_rn,
     row->indicate_eob_p and bot_row_ends_at_zv_p.  */
  int top_row_ends_at_zv_p IF_LINT (= 0), bot_row_ends_at_zv_p IF_LINT (= 0);

  if (w->pseudo_window_p)
    return 0;

  if (!MINI_WINDOW_P (w)
      && (ind = BVAR (XBUFFER (w->buffer), indicate_buffer_boundaries), !NILP (ind)))
    {
      if (EQ (ind, Qleft) || EQ (ind, Qright))
	boundary_top = boundary_bot = arrow_top = arrow_bot = ind;
      else if (CONSP (ind) && CONSP (XCAR (ind)))
	{
	  Lisp_Object pos;
	  if (pos = Fassq (Qt, ind), !NILP (pos))
	    boundary_top = boundary_bot = arrow_top = arrow_bot = XCDR (pos);
	  if (pos = Fassq (Qtop, ind), !NILP (pos))
	    boundary_top = XCDR (pos);
	  if (pos = Fassq (Qbottom, ind), !NILP (pos))
	    boundary_bot = XCDR (pos);
	  if (pos = Fassq (Qup, ind), !NILP (pos))
	    arrow_top = XCDR (pos);
	  if (pos = Fassq (Qdown, ind), !NILP (pos))
	    arrow_bot = XCDR (pos);
	}
      else
	/* Anything else means boundary on left and no arrows.  */
	boundary_top = boundary_bot = Qleft;
    }

  top_ind_rn = bot_ind_rn = -1;
  if (!NILP (ind))
    {
      for (y = w->vscroll, rn = 0;
	   y < yb && rn < nrows;
	   y += row->height, ++rn)
	{
	  row = w->desired_matrix->rows + rn;
	  if (!row->enabled_p)
	    row = w->current_matrix->rows + rn;

	  row->indicate_bob_p = row->indicate_top_line_p = 0;
	  row->indicate_eob_p = row->indicate_bottom_line_p = 0;

	  if (!row->mode_line_p)
	    {
	      if (top_ind_rn < 0 && row->visible_height > 0)
		{
		  if (MATRIX_ROW_START_CHARPOS (row) <= BUF_BEGV (XBUFFER (w->buffer))
		      && !MATRIX_ROW_PARTIALLY_VISIBLE_AT_TOP_P (w, row))
		    row->indicate_bob_p = !NILP (boundary_top);
		  else
		    row->indicate_top_line_p = !NILP (arrow_top);
		  top_ind_rn = rn;
		}

	      if (bot_ind_rn < 0)
		{
		  if (MATRIX_ROW_END_CHARPOS (row) >= BUF_ZV (XBUFFER (w->buffer))
		      && !MATRIX_ROW_PARTIALLY_VISIBLE_AT_BOTTOM_P (w, row))
		    row->indicate_eob_p = !NILP (boundary_bot), bot_ind_rn = rn;
		  else if (y + row->height >= yb)
		    row->indicate_bottom_line_p = !NILP (arrow_bot), bot_ind_rn = rn;
		}
	    }
	}
    }

  empty_pos = BVAR (XBUFFER (w->buffer), indicate_empty_lines);
  if (!NILP (empty_pos) && !EQ (empty_pos, Qright))
    empty_pos = WINDOW_LEFT_FRINGE_WIDTH (w) == 0 ? Qright : Qleft;

  for (y = 0; y < MAX_BITMAP_CACHE; y++)
    bitmap_cache[y] = -1;

#define LEFT_FRINGE(cache, which, partial_p)			\
  (bitmap_cache[cache*4+partial_p] >= 0				\
   ? bitmap_cache[cache*4+partial_p]				\
   : (bitmap_cache[cache*4+partial_p] =				\
      get_logical_fringe_bitmap (w, which, 0, partial_p)))

#define RIGHT_FRINGE(cache, which, partial_p)			\
  (bitmap_cache[cache*4+2+partial_p] >= 0			\
   ? bitmap_cache[cache*4+2+partial_p]				\
   : (bitmap_cache[cache*4+2+partial_p] =			\
      get_logical_fringe_bitmap (w, which, 1, partial_p)))


  /* Extend top-aligned top indicator (or bottom-aligned bottom
     indicator) to adjacent rows if it doesn't fit in one row.  */
  top_ind_min_y = bot_ind_max_y = -1;
  if (top_ind_rn >= 0)
    {
      int bn = NO_FRINGE_BITMAP;

      row = w->desired_matrix->rows + top_ind_rn;
      if (!row->enabled_p)
	row = w->current_matrix->rows + top_ind_rn;

      top_row_ends_at_zv_p = row->ends_at_zv_p;
      if (row->indicate_bob_p)
	{
	  if (EQ (boundary_top, Qleft))
	    bn = ((row->indicate_eob_p && EQ (boundary_bot, Qleft))
		  ? LEFT_FRINGE (1, Qtop_bottom, row->ends_at_zv_p)
		  : LEFT_FRINGE (2, Qtop, 0));
	  else
	    bn = ((row->indicate_eob_p && EQ (boundary_bot, Qright))
		  ? RIGHT_FRINGE (1, Qtop_bottom, row->ends_at_zv_p)
		  : RIGHT_FRINGE (2, Qtop, 0));
	}
      else if (row->indicate_top_line_p)
	{
	  if (EQ (arrow_top, Qleft))
	    bn = LEFT_FRINGE (6, Qup, 0);
	  else
	    bn = RIGHT_FRINGE (6, Qup, 0);
	}

      if (bn != NO_FRINGE_BITMAP)
	{
	  struct fringe_bitmap *fb = get_fringe_bitmap_data (bn);

	  if (fb->align == ALIGN_BITMAP_TOP && fb->period == 0)
	    {
	      struct glyph_row *row1;
	      int top_ind_max_y;

	      top_ind_min_y = WINDOW_HEADER_LINE_HEIGHT (w);
	      top_ind_max_y = top_ind_min_y + fb->height;
	      if (top_ind_max_y > yb)
		top_ind_max_y = yb;

	      for (y = row->y + row->height, rn = top_ind_rn + 1;
		   y < top_ind_max_y && rn < nrows;
		   y += row1->height, rn++)
		{
		  if (bot_ind_rn >= 0 && rn >= bot_ind_rn)
		    break;

		  row1 = w->desired_matrix->rows + rn;
		  if (!row1->enabled_p)
		    row1 = w->current_matrix->rows + rn;

		  row1->indicate_bob_p = row->indicate_bob_p;
		  row1->indicate_top_line_p = row->indicate_top_line_p;
		}
	    }
	}
    }
  if (bot_ind_rn >= 0)
    {
      int bn = NO_FRINGE_BITMAP;

      row = w->desired_matrix->rows + bot_ind_rn;
      if (!row->enabled_p)
	row = w->current_matrix->rows + bot_ind_rn;

      bot_row_ends_at_zv_p = row->ends_at_zv_p;
      if (row->indicate_eob_p)
	{
	  if (EQ (boundary_bot, Qleft))
	    bn = LEFT_FRINGE (3, Qbottom, row->ends_at_zv_p);
	  else
	    bn = RIGHT_FRINGE (3, Qbottom, row->ends_at_zv_p);
	}
      else if (row->indicate_bottom_line_p)
	{
	  if (EQ (arrow_bot, Qleft))
	    bn = LEFT_FRINGE (7, Qdown, 0);
	  else
	    bn = RIGHT_FRINGE (7, Qdown, 0);
	}

      if (bn != NO_FRINGE_BITMAP)
	{
	  struct fringe_bitmap *fb = get_fringe_bitmap_data (bn);

	  if (fb->align == ALIGN_BITMAP_BOTTOM && fb->period == 0)
	    {
	      struct glyph_row *row1;
	      int bot_ind_min_y;

	      bot_ind_max_y = row->y + row->visible_height;
	      bot_ind_min_y = bot_ind_max_y - fb->height;
	      if (bot_ind_min_y < WINDOW_HEADER_LINE_HEIGHT (w))
		bot_ind_min_y = WINDOW_HEADER_LINE_HEIGHT (w);

	      for (y = row->y, rn = bot_ind_rn - 1;
		   y >= bot_ind_min_y && rn >= 0;
		   y -= row1->height, rn--)
		{
		  if (top_ind_rn >= 0 && rn <= top_ind_rn)
		    break;

		  row1 = w->desired_matrix->rows + rn;
		  if (!row1->enabled_p)
		    row1 = w->current_matrix->rows + rn;

		  row1->indicate_eob_p = row->indicate_eob_p;
		  row1->indicate_bottom_line_p = row->indicate_bottom_line_p;
		}
	    }
	}
    }

  for (y = w->vscroll, rn = 0;
       y < yb && rn < nrows;
       y += row->height, rn++)
    {
      int left, right;
      unsigned left_face_id, right_face_id;
      int left_offset, right_offset;
      int periodic_p;

      row = w->desired_matrix->rows + rn;
      cur = w->current_matrix->rows + rn;
      if (!row->enabled_p)
	row = cur;

      left_face_id = right_face_id = DEFAULT_FACE_ID;
      left_offset = right_offset = 0;
      periodic_p = 0;

      /* Decide which bitmap to draw in the left fringe.  */
      if (WINDOW_LEFT_FRINGE_WIDTH (w) == 0)
	left = NO_FRINGE_BITMAP;
      else if (row->left_user_fringe_bitmap != NO_FRINGE_BITMAP)
	{
	  left = row->left_user_fringe_bitmap;
	  left_face_id = row->left_user_fringe_face_id;
	}
      else if ((!row->reversed_p && row->truncated_on_left_p)
	       || (row->reversed_p && row->truncated_on_right_p))
	left = LEFT_FRINGE (0, Qtruncation, 0);
      else if (row->indicate_bob_p && EQ (boundary_top, Qleft))
	{
	  left = ((row->indicate_eob_p && EQ (boundary_bot, Qleft))
		  ? LEFT_FRINGE (1, Qtop_bottom, top_row_ends_at_zv_p)
		  : LEFT_FRINGE (2, Qtop, 0));
	  if (top_ind_min_y >= 0)
	    left_offset = top_ind_min_y - row->y;
	}
      else if (row->indicate_eob_p && EQ (boundary_bot, Qleft))
	{
	  left = LEFT_FRINGE (3, Qbottom, bot_row_ends_at_zv_p);
	  if (bot_ind_max_y >= 0)
	    left_offset = bot_ind_max_y - (row->y + row->visible_height);
	}
      else if ((!row->reversed_p && MATRIX_ROW_CONTINUATION_LINE_P (row))
	       || (row->reversed_p && row->continued_p))
	left = LEFT_FRINGE (4, Qcontinuation, 0);
      else if (row->indicate_empty_line_p && EQ (empty_pos, Qleft))
	left = LEFT_FRINGE (5, Qempty_line, 0);
      else if (row->indicate_top_line_p && EQ (arrow_top, Qleft))
	{
	  left = LEFT_FRINGE (6, Qup, 0);
	  if (top_ind_min_y >= 0)
	    left_offset = top_ind_min_y - row->y;
	}
      else if (row->indicate_bottom_line_p && EQ (arrow_bot, Qleft))
	{
	  left = LEFT_FRINGE (7, Qdown, 0);
	  if (bot_ind_max_y >= 0)
	    left_offset = bot_ind_max_y - (row->y + row->visible_height);
	}
      else
	left = NO_FRINGE_BITMAP;

      /* Decide which bitmap to draw in the right fringe.  */
      if (WINDOW_RIGHT_FRINGE_WIDTH (w) == 0)
	right = NO_FRINGE_BITMAP;
      else if (row->right_user_fringe_bitmap != NO_FRINGE_BITMAP)
	{
	  right = row->right_user_fringe_bitmap;
	  right_face_id = row->right_user_fringe_face_id;
	}
      else if ((!row->reversed_p && row->truncated_on_right_p)
	       || (row->reversed_p && row->truncated_on_left_p))
	right = RIGHT_FRINGE (0, Qtruncation, 0);
      else if (row->indicate_bob_p && EQ (boundary_top, Qright))
	{
	  right = ((row->indicate_eob_p && EQ (boundary_bot, Qright))
		   ? RIGHT_FRINGE (1, Qtop_bottom, top_row_ends_at_zv_p)
		   : RIGHT_FRINGE (2, Qtop, 0));
	  if (top_ind_min_y >= 0)
	    right_offset = top_ind_min_y - row->y;
	}
      else if (row->indicate_eob_p && EQ (boundary_bot, Qright))
	{
	  right = RIGHT_FRINGE (3, Qbottom, bot_row_ends_at_zv_p);
	  if (bot_ind_max_y >= 0)
	    right_offset = bot_ind_max_y - (row->y + row->visible_height);
	}
      else if ((!row->reversed_p && row->continued_p)
	       || (row->reversed_p && MATRIX_ROW_CONTINUATION_LINE_P (row)))
	right = RIGHT_FRINGE (4, Qcontinuation, 0);
      else if (row->indicate_top_line_p && EQ (arrow_top, Qright))
	{
	  right = RIGHT_FRINGE (6, Qup, 0);
	  if (top_ind_min_y >= 0)
	    right_offset = top_ind_min_y - row->y;
	}
      else if (row->indicate_bottom_line_p && EQ (arrow_bot, Qright))
	{
	  right = RIGHT_FRINGE (7, Qdown, 0);
	  if (bot_ind_max_y >= 0)
	    right_offset = bot_ind_max_y - (row->y + row->visible_height);
	}
      else if (row->indicate_empty_line_p && EQ (empty_pos, Qright))
	right = RIGHT_FRINGE (5, Qempty_line, 0);
      else
	right = NO_FRINGE_BITMAP;

      periodic_p = (get_fringe_bitmap_data (left)->period != 0
		    || get_fringe_bitmap_data (right)->period != 0);

      if (row->y != cur->y
	  || row->visible_height != cur->visible_height
	  || row->ends_at_zv_p != cur->ends_at_zv_p
	  || left != cur->left_fringe_bitmap
	  || right != cur->right_fringe_bitmap
	  || left_face_id != cur->left_fringe_face_id
	  || right_face_id != cur->right_fringe_face_id
	  || left_offset != cur->left_fringe_offset
	  || right_offset != cur->right_fringe_offset
	  || periodic_p != cur->fringe_bitmap_periodic_p
	  || cur->redraw_fringe_bitmaps_p)
	{
	  redraw_p = row->redraw_fringe_bitmaps_p = 1;
	  if (!keep_current_p)
	    {
	      cur->redraw_fringe_bitmaps_p = 1;
	      cur->left_fringe_bitmap = left;
	      cur->right_fringe_bitmap = right;
	      cur->left_fringe_face_id = left_face_id;
	      cur->right_fringe_face_id = right_face_id;
	      cur->left_fringe_offset = left_offset;
	      cur->right_fringe_offset = right_offset;
	      cur->fringe_bitmap_periodic_p = periodic_p;
	    }
	}

      if (row->overlay_arrow_bitmap < 0)
	row->overlay_arrow_bitmap = get_logical_fringe_bitmap (w, Qoverlay_arrow, 0, 0);

      if (row->overlay_arrow_bitmap != cur->overlay_arrow_bitmap)
	{
	  redraw_p = row->redraw_fringe_bitmaps_p = 1;
	  if (!keep_current_p)
	    {
	      cur->redraw_fringe_bitmaps_p = 1;
	      cur->overlay_arrow_bitmap = row->overlay_arrow_bitmap;
	    }
	}

      row->left_fringe_bitmap = left;
      row->right_fringe_bitmap = right;
      row->left_fringe_face_id = left_face_id;
      row->right_fringe_face_id = right_face_id;
      row->left_fringe_offset = left_offset;
      row->right_fringe_offset = right_offset;
      row->fringe_bitmap_periodic_p = periodic_p;
    }

  return redraw_p && !keep_current_p;
}
Exemplo n.º 4
0
EMACS_INT
buf_bytepos_to_charpos (struct buffer *b, EMACS_INT bytepos)
{
  struct Lisp_Marker *tail;
  EMACS_INT best_above, best_above_byte;
  EMACS_INT best_below, best_below_byte;

  if (bytepos < BUF_BEG_BYTE (b) || bytepos > BUF_Z_BYTE (b))
    abort ();

  best_above = BUF_Z (b);
  best_above_byte = BUF_Z_BYTE (b);

  /* If this buffer has as many characters as bytes,
     each character must be one byte.
     This takes care of the case where enable-multibyte-characters is nil.  */
  if (best_above == best_above_byte)
    return bytepos;

  best_below = BEG;
  best_below_byte = BEG_BYTE;

  CONSIDER (BUF_PT_BYTE (b), BUF_PT (b));
  CONSIDER (BUF_GPT_BYTE (b), BUF_GPT (b));
  CONSIDER (BUF_BEGV_BYTE (b), BUF_BEGV (b));
  CONSIDER (BUF_ZV_BYTE (b), BUF_ZV (b));

  if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
    CONSIDER (cached_bytepos, cached_charpos);

  for (tail = BUF_MARKERS (b); tail; tail = tail->next)
    {
      CONSIDER (tail->bytepos, tail->charpos);

      /* If we are down to a range of 50 chars,
	 don't bother checking any other markers;
	 scan the intervening chars directly now.  */
      if (best_above - best_below < 50)
	break;
    }

  /* We get here if we did not exactly hit one of the known places.
     We have one known above and one known below.
     Scan, counting characters, from whichever one is closer.  */

  if (bytepos - best_below_byte < best_above_byte - bytepos)
    {
      int record = bytepos - best_below_byte > 5000;

      while (best_below_byte < bytepos)
	{
	  best_below++;
	  BUF_INC_POS (b, best_below_byte);
	}

      /* If this position is quite far from the nearest known position,
	 cache the correspondence by creating a marker here.
	 It will last until the next GC.
	 But don't do it if BUF_MARKERS is nil;
	 that is a signal from Fset_buffer_multibyte.  */
      if (record && BUF_MARKERS (b))
	{
	  Lisp_Object marker, buffer;
	  marker = Fmake_marker ();
	  XSETBUFFER (buffer, b);
	  set_marker_both (marker, buffer, best_below, best_below_byte);
	}

      if (byte_debug_flag)
	byte_char_debug_check (b, best_below, bytepos);

      cached_buffer = b;
      cached_modiff = BUF_MODIFF (b);
      cached_charpos = best_below;
      cached_bytepos = best_below_byte;

      return best_below;
    }
  else
    {
      int record = best_above_byte - bytepos > 5000;

      while (best_above_byte > bytepos)
	{
	  best_above--;
	  BUF_DEC_POS (b, best_above_byte);
	}

      /* If this position is quite far from the nearest known position,
	 cache the correspondence by creating a marker here.
	 It will last until the next GC.
	 But don't do it if BUF_MARKERS is nil;
	 that is a signal from Fset_buffer_multibyte.  */
      if (record && BUF_MARKERS (b))
	{
	  Lisp_Object marker, buffer;
	  marker = Fmake_marker ();
	  XSETBUFFER (buffer, b);
	  set_marker_both (marker, buffer, best_above, best_above_byte);
	}

      if (byte_debug_flag)
	byte_char_debug_check (b, best_above, bytepos);

      cached_buffer = b;
      cached_modiff = BUF_MODIFF (b);
      cached_charpos = best_above;
      cached_bytepos = best_above_byte;

      return best_above;
    }
}
Exemplo n.º 5
0
ptrdiff_t
buf_charpos_to_bytepos (struct buffer *b, ptrdiff_t charpos)
{
    struct Lisp_Marker *tail;
    ptrdiff_t best_above, best_above_byte;
    ptrdiff_t best_below, best_below_byte;

    eassert (BUF_BEG (b) <= charpos && charpos <= BUF_Z (b));

    best_above = BUF_Z (b);
    best_above_byte = BUF_Z_BYTE (b);

    /* If this buffer has as many characters as bytes,
       each character must be one byte.
       This takes care of the case where enable-multibyte-characters is nil.  */
    if (best_above == best_above_byte)
        return charpos;

    best_below = BEG;
    best_below_byte = BEG_BYTE;

    /* We find in best_above and best_above_byte
       the closest known point above CHARPOS,
       and in best_below and best_below_byte
       the closest known point below CHARPOS,

       If at any point we can tell that the space between those
       two best approximations is all single-byte,
       we interpolate the result immediately.  */

    CONSIDER (BUF_PT (b), BUF_PT_BYTE (b));
    CONSIDER (BUF_GPT (b), BUF_GPT_BYTE (b));
    CONSIDER (BUF_BEGV (b), BUF_BEGV_BYTE (b));
    CONSIDER (BUF_ZV (b), BUF_ZV_BYTE (b));

    if (b == cached_buffer && BUF_MODIFF (b) == cached_modiff)
        CONSIDER (cached_charpos, cached_bytepos);

    for (tail = BUF_MARKERS (b); tail; tail = tail->next)
    {
        CONSIDER (tail->charpos, tail->bytepos);

        /* If we are down to a range of 50 chars,
        don't bother checking any other markers;
         scan the intervening chars directly now.  */
        if (best_above - best_below < 50)
            break;
    }

    /* We get here if we did not exactly hit one of the known places.
       We have one known above and one known below.
       Scan, counting characters, from whichever one is closer.  */

    if (charpos - best_below < best_above - charpos)
    {
        bool record = charpos - best_below > 5000;

        while (best_below != charpos)
        {
            best_below++;
            BUF_INC_POS (b, best_below_byte);
        }

        /* If this position is quite far from the nearest known position,
        cache the correspondence by creating a marker here.
         It will last until the next GC.  */
        if (record)
            build_marker (b, best_below, best_below_byte);

        byte_char_debug_check (b, best_below, best_below_byte);

        cached_buffer = b;
        cached_modiff = BUF_MODIFF (b);
        cached_charpos = best_below;
        cached_bytepos = best_below_byte;

        return best_below_byte;
    }
    else
    {
        bool record = best_above - charpos > 5000;

        while (best_above != charpos)
        {
            best_above--;
            BUF_DEC_POS (b, best_above_byte);
        }

        /* If this position is quite far from the nearest known position,
        cache the correspondence by creating a marker here.
         It will last until the next GC.  */
        if (record)
            build_marker (b, best_above, best_above_byte);

        byte_char_debug_check (b, best_above, best_above_byte);

        cached_buffer = b;
        cached_modiff = BUF_MODIFF (b);
        cached_charpos = best_above;
        cached_bytepos = best_above_byte;

        return best_above_byte;
    }
}