dispnew.c 73.7 KB
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/* Updating of data structures for redisplay.
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   Copyright (C) 1985, 86, 87, 88, 93, 94, 95 Free Software Foundation, Inc.
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This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.

GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */


#include <signal.h>

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#include <config.h>
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#include <stdio.h>
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#include <ctype.h>

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#include "lisp.h"
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#include "termchar.h"
#include "termopts.h"
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#include "termhooks.h"
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#include "cm.h"
#include "dispextern.h"
#include "buffer.h"
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#include "frame.h"
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#include "window.h"
#include "commands.h"
#include "disptab.h"
#include "indent.h"
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#include "intervals.h"
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#include "systty.h"
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#include "syssignal.h"
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#ifdef HAVE_X_WINDOWS
#include "xterm.h"
#endif	/* HAVE_X_WINDOWS */

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/* Include systime.h after xterm.h to avoid double inclusion of time.h. */
#include "systime.h"

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#include <errno.h>

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#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))

/* Get number of chars of output now in the buffer of a stdio stream.
   This ought to be built in in stdio, but it isn't.
   Some s- files override this because their stdio internals differ.  */
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#ifdef __GNU_LIBRARY__
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/* The s- file might have overridden the definition with one that works for
   the system's C library.  But we are using the GNU C library, so this is
   the right definition for every system.  */
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#ifdef GNU_LIBRARY_PENDING_OUTPUT_COUNT
#define PENDING_OUTPUT_COUNT GNU_LIBRARY_PENDING_OUTPUT_COUNT
#else
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#undef	PENDING_OUTPUT_COUNT
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#define	PENDING_OUTPUT_COUNT(FILE) ((FILE)->__bufp - (FILE)->__buffer)
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#endif
#else /* not __GNU_LIBRARY__ */
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#ifndef PENDING_OUTPUT_COUNT
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#define PENDING_OUTPUT_COUNT(FILE) ((FILE)->_ptr - (FILE)->_base)
#endif
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#endif
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static void change_frame_size_1 ();

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/* Nonzero upon entry to redisplay means do not assume anything about
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   current contents of actual terminal frame; clear and redraw it.  */
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int frame_garbaged;
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/* Nonzero means last display completed.  Zero means it was preempted. */

int display_completed;

/* Lisp variable visible-bell; enables use of screen-flash
   instead of audible bell.  */

int visible_bell;

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/* Invert the color of the whole frame, at a low level.  */
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int inverse_video;

/* Line speed of the terminal.  */

int baud_rate;

/* nil or a symbol naming the window system under which emacs is
   running ('x is the only current possibility).  */

Lisp_Object Vwindow_system;

/* Version number of X windows: 10, 11 or nil.  */
Lisp_Object Vwindow_system_version;

/* Vector of glyph definitions.  Indexed by glyph number,
   the contents are a string which is how to output the glyph.

   If Vglyph_table is nil, a glyph is output by using its low 8 bits
   as a character code.  */

Lisp_Object Vglyph_table;

/* Display table to use for vectors that don't specify their own.  */

Lisp_Object Vstandard_display_table;

/* Nonzero means reading single-character input with prompt
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   so put cursor on minibuffer after the prompt.
   positive means at end of text in echo area;
   negative means at beginning of line.  */
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int cursor_in_echo_area;
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Lisp_Object Qdisplay_table;
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/* The currently selected frame.
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   In a single-frame version, this variable always holds the address of
   the_only_frame.  */
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FRAME_PTR selected_frame;
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/* A frame which is not just a minibuffer, or 0 if there are no such
   frames.  This is usually the most recent such frame that was
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   selected.  In a single-frame version, this variable always holds
   the address of the_only_frame.  */
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FRAME_PTR last_nonminibuf_frame;
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/* In a single-frame version, the information that would otherwise
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   exist inside frame objects lives in the following structure instead.

   NOTE: the_only_frame is not checked for garbage collection; don't
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   store collectible objects in any of its fields!
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   You're not/The only frame in town/...  */
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#ifndef MULTI_FRAME
struct frame the_only_frame;
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#endif
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/* This is a vector, made larger whenever it isn't large enough,
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   which is used inside `update_frame' to hold the old contents
   of the FRAME_PHYS_LINES of the frame being updated.  */
struct frame_glyphs **ophys_lines;
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/* Length of vector currently allocated.  */
int ophys_lines_length;

FILE *termscript;	/* Stdio stream being used for copy of all output.  */

struct cm Wcm;		/* Structure for info on cursor positioning */

extern short ospeed;	/* Output speed (from sg_ospeed) */

int delayed_size_change;  /* 1 means SIGWINCH happened when not safe.  */

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#ifdef MULTI_FRAME
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DEFUN ("redraw-frame", Fredraw_frame, Sredraw_frame, 1, 1, 0,
  "Clear frame FRAME and output again what is supposed to appear on it.")
  (frame)
     Lisp_Object frame;
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{
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  FRAME_PTR f;
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  CHECK_LIVE_FRAME (frame, 0);
  f = XFRAME (frame);
  update_begin (f);
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  /*  set_terminal_modes (); */
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  clear_frame ();
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  clear_frame_records (f);
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  update_end (f);
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  fflush (stdout);
  windows_or_buffers_changed++;
  /* Mark all windows as INaccurate,
     so that every window will have its redisplay done.  */
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  mark_window_display_accurate (FRAME_ROOT_WINDOW (f), 0);
  f->garbaged = 0;
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  return Qnil;
}

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redraw_frame (f)
     FRAME_PTR f;
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{
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  Lisp_Object frame;
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  XSETFRAME (frame, f);
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  Fredraw_frame (frame);
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}

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#else
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DEFUN ("redraw-frame", Fredraw_frame, Sredraw_frame, 1, 1, 0,
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  /* Don't confuse make-docfile by having two doc strings for this function.
     make-docfile does not pay attention to #if, for good reason!  */
  0)
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  (frame)
     Lisp_Object frame;
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{
  update_begin (0);
  set_terminal_modes ();
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  clear_frame ();
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  update_end (0);
  fflush (stdout);
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  clear_frame_records (0);
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  windows_or_buffers_changed++;
  /* Mark all windows as INaccurate,
     so that every window will have its redisplay done.  */
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  mark_window_display_accurate (FRAME_ROOT_WINDOW (0), 0);
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  return Qnil;
}

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#endif

DEFUN ("redraw-display", Fredraw_display, Sredraw_display, 0, 0, "",
  "Clear and redisplay all visible frames.")
  ()
{
  Lisp_Object tail, frame;

  FOR_EACH_FRAME (tail, frame)
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    if (FRAME_VISIBLE_P (XFRAME (frame)))
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      Fredraw_frame (frame);

  return Qnil;
}

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/* This is used when frame_garbaged is set.
   Redraw the individual frames marked as garbaged.  */

void
redraw_garbaged_frames ()
{
  Lisp_Object tail, frame;

  FOR_EACH_FRAME (tail, frame)
    if (FRAME_VISIBLE_P (XFRAME (frame))
	&& FRAME_GARBAGED_P (XFRAME (frame)))
      Fredraw_frame (frame);
}

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static struct frame_glyphs *
make_frame_glyphs (frame, empty)
     register FRAME_PTR frame;
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     int empty;
{
  register int i;
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  register width = FRAME_WIDTH (frame);
  register height = FRAME_HEIGHT (frame);
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  register struct frame_glyphs *new
    = (struct frame_glyphs *) xmalloc (sizeof (struct frame_glyphs));
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  SET_GLYPHS_FRAME (new, frame);
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  new->height = height;
  new->width = width;
  new->used = (int *) xmalloc (height * sizeof (int));
  new->glyphs = (GLYPH **) xmalloc (height * sizeof (GLYPH *));
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  new->charstarts = (int **) xmalloc (height * sizeof (int *));
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  new->highlight = (char *) xmalloc (height * sizeof (char));
  new->enable = (char *) xmalloc (height * sizeof (char));
  bzero (new->enable, height * sizeof (char));
  new->bufp = (int *) xmalloc (height * sizeof (int));

#ifdef HAVE_X_WINDOWS
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  if (FRAME_X_P (frame))
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    {
      new->top_left_x = (short *) xmalloc (height * sizeof (short));
      new->top_left_y = (short *) xmalloc (height * sizeof (short));
      new->pix_width = (short *) xmalloc (height * sizeof (short));
      new->pix_height = (short *) xmalloc (height * sizeof (short));
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      new->max_ascent = (short *) xmalloc (height * sizeof (short));
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    }
#endif

  if (empty)
    {
      /* Make the buffer used by decode_mode_spec.  This buffer is also
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         used as temporary storage when updating the frame.  See scroll.c. */
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      unsigned int total_glyphs = (width + 2) * sizeof (GLYPH);
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      unsigned int total_charstarts = (width + 2) * sizeof (int);
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      new->total_contents = (GLYPH *) xmalloc (total_glyphs);
      bzero (new->total_contents, total_glyphs);
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      new->total_charstarts = (int *) xmalloc (total_charstarts);
      bzero (new->total_charstarts, total_glyphs);
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    }
  else
    {
      unsigned int total_glyphs = height * (width + 2) * sizeof (GLYPH);

      new->total_contents = (GLYPH *) xmalloc (total_glyphs);
      bzero (new->total_contents, total_glyphs);
      for (i = 0; i < height; i++)
	new->glyphs[i] = new->total_contents + i * (width + 2) + 1;
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      if (!FRAME_TERMCAP_P (frame))
	{
	  unsigned int total_charstarts = height * (width + 2) * sizeof (int);

	  new->total_charstarts = (int *) xmalloc (total_charstarts);
	  bzero (new->total_charstarts, total_charstarts);
	  for (i = 0; i < height; i++)
	    new->charstarts[i] = new->total_charstarts + i * (width + 2) + 1;
	}
      else
	{
	  /* Without a window system, we don't really need charstarts.
	     So use a small amount of space to make enough data structure
	     to prevent crashes in display_text_line.  */
	  new->total_charstarts = (int *) xmalloc ((width + 2) * sizeof (int));
	  for (i = 0; i < height; i++)
	    new->charstarts[i] = new->total_charstarts;
	}
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    }

  return new;
}

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void
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free_frame_glyphs (frame, glyphs)
     FRAME_PTR frame;
     struct frame_glyphs *glyphs;
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{
  if (glyphs->total_contents)
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    xfree (glyphs->total_contents);
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  if (glyphs->total_charstarts)
    xfree (glyphs->total_charstarts);
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  xfree (glyphs->used);
  xfree (glyphs->glyphs);
  xfree (glyphs->highlight);
  xfree (glyphs->enable);
  xfree (glyphs->bufp);
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  if (glyphs->charstarts)
    xfree (glyphs->charstarts);
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#ifdef HAVE_X_WINDOWS
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  if (FRAME_X_P (frame))
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    {
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      xfree (glyphs->top_left_x);
      xfree (glyphs->top_left_y);
      xfree (glyphs->pix_width);
      xfree (glyphs->pix_height);
      xfree (glyphs->max_ascent);
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    }
#endif

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  xfree (glyphs);
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}

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void
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remake_frame_glyphs (frame)
     FRAME_PTR frame;
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{
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  if (FRAME_CURRENT_GLYPHS (frame))
    free_frame_glyphs (frame, FRAME_CURRENT_GLYPHS (frame));
  if (FRAME_DESIRED_GLYPHS (frame))
    free_frame_glyphs (frame, FRAME_DESIRED_GLYPHS (frame));
  if (FRAME_TEMP_GLYPHS (frame))
    free_frame_glyphs (frame, FRAME_TEMP_GLYPHS (frame));

  if (FRAME_MESSAGE_BUF (frame))
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    {
      /* Reallocate the frame's message buffer; remember that
	 echo_area_glyphs may be pointing here.  */
      char *old_message_buf = FRAME_MESSAGE_BUF (frame);

      FRAME_MESSAGE_BUF (frame)
	= (char *) xrealloc (FRAME_MESSAGE_BUF (frame),
			     FRAME_WIDTH (frame) + 1);

      if (echo_area_glyphs == old_message_buf)
	echo_area_glyphs = FRAME_MESSAGE_BUF (frame);
      if (previous_echo_glyphs == old_message_buf)
	previous_echo_glyphs = FRAME_MESSAGE_BUF (frame);
    }
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  else
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    FRAME_MESSAGE_BUF (frame)
      = (char *) xmalloc (FRAME_WIDTH (frame) + 1);
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  FRAME_CURRENT_GLYPHS (frame) = make_frame_glyphs (frame, 0);
  FRAME_DESIRED_GLYPHS (frame) = make_frame_glyphs (frame, 0);
  FRAME_TEMP_GLYPHS (frame) = make_frame_glyphs (frame, 1);
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  if (! FRAME_TERMCAP_P (frame) || frame == selected_frame)
    SET_FRAME_GARBAGED (frame);
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}

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/* Return the hash code of contents of line VPOS in frame-matrix M.  */
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static int
line_hash_code (m, vpos)
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     register struct frame_glyphs *m;
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     int vpos;
{
  register GLYPH *body, *end;
  register int h = 0;

  if (!m->enable[vpos])
    return 0;

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  /* Give all highlighted lines the same hash code
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     so as to encourage scrolling to leave them in place.  */
  if (m->highlight[vpos])
    return -1;

  body = m->glyphs[vpos];

  if (must_write_spaces)
    while (1)
      {
	GLYPH g = *body++;

	if (g == 0)
	  break;
	h = (((h << 4) + (h >> 24)) & 0x0fffffff) + g - SPACEGLYPH;
      }
  else
    while (1)
      {
	GLYPH g = *body++;

	if (g == 0)
	  break;
	h = (((h << 4) + (h >> 24)) & 0x0fffffff) + g;
      }

  if (h)
    return h;
  return 1;
}

/* Return number of characters in line in M at vpos VPOS,
   except don't count leading and trailing spaces
   unless the terminal requires those to be explicitly output.  */

static unsigned int
line_draw_cost (m, vpos)
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     struct frame_glyphs *m;
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     int vpos;
{
  register GLYPH *beg = m->glyphs[vpos];
  register GLYPH *end = m->glyphs[vpos] + m->used[vpos];
  register int i;
  register int tlen = GLYPH_TABLE_LENGTH;
  register Lisp_Object *tbase = GLYPH_TABLE_BASE;

  /* Ignore trailing and leading spaces if we can.  */
  if (!must_write_spaces)
    {
      while ((end != beg) && (*end == SPACEGLYPH))
	--end;
      if (end == beg)
	return (0); /* All blank line. */

      while (*beg == SPACEGLYPH)
	++beg;
    }

  /* If we don't have a glyph-table, each glyph is one character,
     so return the number of glyphs.  */
  if (tbase == 0)
    return end - beg;

  /* Otherwise, scan the glyphs and accumulate their total size in I.  */
  i = 0;
  while ((beg <= end) && *beg)
    {
      register GLYPH g = *beg++;

      if (GLYPH_SIMPLE_P (tbase, tlen, g))
	i += 1;
      else
	i += GLYPH_LENGTH (tbase, g);
    }
  return i;
}

/* The functions on this page are the interface from xdisp.c to redisplay.

   The only other interface into redisplay is through setting
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   FRAME_CURSOR_X (frame) and FRAME_CURSOR_Y (frame)
   and SET_FRAME_GARBAGED (frame).  */
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/* cancel_line eliminates any request to display a line at position `vpos' */

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cancel_line (vpos, frame)
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     int vpos;
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     register FRAME_PTR frame;
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{
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  FRAME_DESIRED_GLYPHS (frame)->enable[vpos] = 0;
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}

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clear_frame_records (frame)
     register FRAME_PTR frame;
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{
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  bzero (FRAME_CURRENT_GLYPHS (frame)->enable, FRAME_HEIGHT (frame));
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}

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/* Clear out all display lines for a coming redisplay.  */

void
init_desired_glyphs (frame)
     register FRAME_PTR frame;
{
  register struct frame_glyphs *desired_glyphs = FRAME_DESIRED_GLYPHS (frame);
  int vpos;
  int height = FRAME_HEIGHT (frame);

  for (vpos = 0; vpos < height; vpos++)
    desired_glyphs->enable[vpos] = 0;
}

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/* Prepare to display on line VPOS starting at HPOS within it.  */

void
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get_display_line (frame, vpos, hpos)
     register FRAME_PTR frame;
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     int vpos;
     register int hpos;
{
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  register struct frame_glyphs *glyphs;
  register struct frame_glyphs *desired_glyphs = FRAME_DESIRED_GLYPHS (frame);
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  register GLYPH *p;

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  if (vpos < 0)
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    abort ();

  if (! desired_glyphs->enable[vpos])
    {
      desired_glyphs->used[vpos] = 0;
      desired_glyphs->highlight[vpos] = 0;
      desired_glyphs->enable[vpos] = 1;
    }

  if (hpos > desired_glyphs->used[vpos])
    {
      GLYPH *g = desired_glyphs->glyphs[vpos] + desired_glyphs->used[vpos];
      GLYPH *end = desired_glyphs->glyphs[vpos] + hpos;

      desired_glyphs->used[vpos] = hpos;
      while (g != end)
	*g++ = SPACEGLYPH;
    }
}

/* Like bcopy except never gets confused by overlap.  */

void
safe_bcopy (from, to, size)
     char *from, *to;
     int size;
{
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  if (size <= 0 || from == to)
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    return;

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  /* If the source and destination don't overlap, then bcopy can
     handle it.  If they do overlap, but the destination is lower in
     memory than the source, we'll assume bcopy can handle that.  */
  if (to < from || from + size <= to)
    bcopy (from, to, size);

  /* Otherwise, we'll copy from the end.  */
  else
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    {
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      register char *endf = from + size;
      register char *endt = to + size;
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      /* If TO - FROM is large, then we should break the copy into
	 nonoverlapping chunks of TO - FROM bytes each.  However, if
	 TO - FROM is small, then the bcopy function call overhead
	 makes this not worth it.  The crossover point could be about
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	 anywhere.  Since I don't think the obvious copy loop is too
	 bad, I'm trying to err in its favor.  */
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      if (to - from < 64)
	{
	  do
	    *--endt = *--endf;
	  while (endf != from);
	}
      else
	{
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	  for (;;)
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	    {
	      endt -= (to - from);
	      endf -= (to - from);

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	      if (endt < to)
		break;

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	      bcopy (endf, endt, to - from);
	    }
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	  /* If SIZE wasn't a multiple of TO - FROM, there will be a
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	     little left over.  The amount left over is
	     (endt + (to - from)) - to, which is endt - from.  */
	  bcopy (from, to, endt - from);
	}
    }
}     

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/* Rotate a vector of SIZE bytes right, by DISTANCE bytes.
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   DISTANCE may be negative.  */

static void
rotate_vector (vector, size, distance)
     char *vector;
     int size;
     int distance;
{
  char *temp = (char *) alloca (size);

  if (distance < 0)
    distance += size;

  bcopy (vector, temp + distance, size - distance);
  bcopy (vector + size - distance, temp, distance);
  bcopy (temp, vector, size);
}

/* Scroll lines from vpos FROM up to but not including vpos END
   down by AMOUNT lines (AMOUNT may be negative).
   Returns nonzero if done, zero if terminal cannot scroll them.  */

int
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scroll_frame_lines (frame, from, end, amount, newpos)
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     register FRAME_PTR frame;
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     int from, end, amount, newpos;
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{
  register int i;
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  register struct frame_glyphs *current_frame
    = FRAME_CURRENT_GLYPHS (frame);
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  int pos_adjust;
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  int width = FRAME_WIDTH (frame);
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  if (!line_ins_del_ok)
    return 0;

  if (amount == 0)
    return 1;

  if (amount > 0)
    {
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      update_begin (frame);
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      set_terminal_window (end + amount);
      if (!scroll_region_ok)
	ins_del_lines (end, -amount);
      ins_del_lines (from, amount);
      set_terminal_window (0);

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      rotate_vector (current_frame->glyphs + from,
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		     sizeof (GLYPH *) * (end + amount - from),
		     amount * sizeof (GLYPH *));

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      rotate_vector (current_frame->charstarts + from,
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		     sizeof (int *) * (end + amount - from),
		     amount * sizeof (int *));

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      safe_bcopy (current_frame->used + from,
		  current_frame->used + from + amount,
		  (end - from) * sizeof current_frame->used[0]);

      safe_bcopy (current_frame->highlight + from,
		  current_frame->highlight + from + amount,
		  (end - from) * sizeof current_frame->highlight[0]);

      safe_bcopy (current_frame->enable + from,
		  current_frame->enable + from + amount,
		  (end - from) * sizeof current_frame->enable[0]);

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      /* Adjust the lines by an amount
	 that puts the first of them at NEWPOS.  */
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      pos_adjust = newpos - current_frame->charstarts[from + amount][0];
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      /* Offset each char position in the charstarts lines we moved
	 by pos_adjust.  */
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      for (i = from + amount; i < end + amount; i++)
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	{
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	  int *line = current_frame->charstarts[i];
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	  int col;
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	  for (col = 0; col < width; col++)
	    if (line[col] > 0)
	      line[col] += pos_adjust;
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	}
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      for (i = from; i < from + amount; i++)
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	{
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	  int *line = current_frame->charstarts[i];
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	  int col;
	  line[0] = -1;
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	  for (col = 0; col < width; col++)
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	    line[col] = 0;
	}

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      /* Mark the lines made empty by scrolling as enabled, empty and
	 normal video.  */
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      bzero (current_frame->used + from,
	     amount * sizeof current_frame->used[0]);
      bzero (current_frame->highlight + from,
	     amount * sizeof current_frame->highlight[0]);
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      for (i = from; i < from + amount; i++)
	{
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	  current_frame->glyphs[i][0] = '\0';
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	  current_frame->charstarts[i][0] = -1;
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	  current_frame->enable[i] = 1;
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	}

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      safe_bcopy (current_frame->bufp + from,
		  current_frame->bufp + from + amount,
		  (end - from) * sizeof current_frame->bufp[0]);
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#ifdef HAVE_X_WINDOWS
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      if (FRAME_X_P (frame))
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	{
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	  safe_bcopy (current_frame->top_left_x + from,
		      current_frame->top_left_x + from + amount,
		      (end - from) * sizeof current_frame->top_left_x[0]);
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	  safe_bcopy (current_frame->top_left_y + from,
		      current_frame->top_left_y + from + amount,
		      (end - from) * sizeof current_frame->top_left_y[0]);
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	  safe_bcopy (current_frame->pix_width + from,
		      current_frame->pix_width + from + amount,
		      (end - from) * sizeof current_frame->pix_width[0]);
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	  safe_bcopy (current_frame->pix_height + from,
		      current_frame->pix_height + from + amount,
		      (end - from) * sizeof current_frame->pix_height[0]);
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	  safe_bcopy (current_frame->max_ascent + from,
		      current_frame->max_ascent + from + amount,
		      (end - from) * sizeof current_frame->max_ascent[0]);
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	}
#endif				/* HAVE_X_WINDOWS */

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      update_end (frame);
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    }
  if (amount < 0)
    {
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      update_begin (frame);
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      set_terminal_window (end);
      ins_del_lines (from + amount, amount);
      if (!scroll_region_ok)
	ins_del_lines (end + amount, -amount);
      set_terminal_window (0);

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      rotate_vector (current_frame->glyphs + from + amount,
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		     sizeof (GLYPH *) * (end - from - amount),
		     amount * sizeof (GLYPH *));

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      rotate_vector (current_frame->charstarts + from + amount,
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		     sizeof (int *) * (end - from - amount),
		     amount * sizeof (int *));

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      safe_bcopy (current_frame->used + from,
		  current_frame->used + from + amount,
		  (end - from) * sizeof current_frame->used[0]);

      safe_bcopy (current_frame->highlight + from,
		  current_frame->highlight + from + amount,
		  (end - from) * sizeof current_frame->highlight[0]);

      safe_bcopy (current_frame->enable + from,
		  current_frame->enable + from + amount,
		  (end - from) * sizeof current_frame->enable[0]);

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      /* Adjust the lines by an amount
	 that puts the first of them at NEWPOS.  */
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      pos_adjust = newpos - current_frame->charstarts[from + amount][0];
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      /* Offset each char position in the charstarts lines we moved
	 by pos_adjust.  */
      for (i = from + amount; i < end + amount; i++)
	{
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	  int *line = current_frame->charstarts[i];
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	  int col;
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	  for (col = 0; col < width; col++)
	    if (line[col] > 0)
	      line[col] += pos_adjust;
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	}
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      for (i = end + amount; i < end; i++)
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	{
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	  int *line = current_frame->charstarts[i];
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	  int col;
	  line[0] = -1;
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	  for (col = 0; col < width; col++)
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	    line[col] = 0;
	}

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      /* Mark the lines made empty by scrolling as enabled, empty and
	 normal video.  */
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      bzero (current_frame->used + end + amount,
	     - amount * sizeof current_frame->used[0]);
      bzero (current_frame->highlight + end + amount,
	     - amount * sizeof current_frame->highlight[0]);
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      for (i = end + amount; i < end; i++)
	{
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	  current_frame->glyphs[i][0] = '\0';
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	  current_frame->charstarts[i][0] = 0;
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	  current_frame->enable[i] = 1;
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	}

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      safe_bcopy (current_frame->bufp + from,
		  current_frame->bufp + from + amount,
		  (end - from) * sizeof current_frame->bufp[0]);
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#ifdef HAVE_X_WINDOWS
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      if (FRAME_X_P (frame))
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	{
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	  safe_bcopy (current_frame->top_left_x + from,
		      current_frame->top_left_x + from + amount,
		      (end - from) * sizeof current_frame->top_left_x[0]);
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	  safe_bcopy (current_frame->top_left_y + from,
		      current_frame->top_left_y + from + amount,
		      (end - from) * sizeof current_frame->top_left_y[0]);
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	  safe_bcopy (current_frame->pix_width + from,
		      current_frame->pix_width + from + amount,
		      (end - from) * sizeof current_frame->pix_width[0]);
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	  safe_bcopy (current_frame->pix_height + from,
		      current_frame->pix_height + from + amount,
		      (end - from) * sizeof current_frame->pix_height[0]);
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	  safe_bcopy (current_frame->max_ascent + from,
		      current_frame->max_ascent + from + amount,
		      (end - from) * sizeof current_frame->max_ascent[0]);
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	}
#endif				/* HAVE_X_WINDOWS */

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      update_end (frame);
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    }
  return 1;
}

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/* After updating a window W that isn't the full frame wide,
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   copy all the columns that W does not occupy
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   into the FRAME_DESIRED_GLYPHS (frame) from the FRAME_PHYS_GLYPHS (frame)
   so that update_frame will not change those columns.  */
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preserve_other_columns (w)
     struct window *w;
{
  register int vpos;
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  register struct frame_glyphs *current_frame, *desired_frame;
  register FRAME_PTR frame = XFRAME (w->frame);
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  int start = XFASTINT (w->left);
  int end = XFASTINT (w->left) + XFASTINT (w->width);
  int bot = XFASTINT (w->top) + XFASTINT (w->height);

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  current_frame = FRAME_CURRENT_GLYPHS (frame);
  desired_frame = FRAME_DESIRED_GLYPHS (frame);
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  for (vpos = XFASTINT (w->top); vpos < bot; vpos++)
    {
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      if (current_frame->enable[vpos] && desired_frame->enable[vpos])
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	{
	  if (start > 0)
	    {
	      int len;

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	      bcopy (current_frame->glyphs[vpos],
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		     desired_frame->glyphs[vpos],
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		     start * sizeof (current_frame->glyphs[vpos][0]));
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	      bcopy (current_frame->charstarts[vpos],
		     desired_frame->charstarts[vpos],
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		     start * sizeof (current_frame->charstarts[vpos][0]));
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	      len = min (start, current_frame->used[vpos]);
	      if (desired_frame->used[vpos] < len)
		desired_frame->used[vpos] = len;
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	    }
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	  if (current_frame->used[vpos] > end
	      && desired_frame->used[vpos] < current_frame->used[vpos])
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	    {
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	      while (desired_frame->used[vpos] < end)
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		{
		  int used = desired_frame->used[vpos]++;
		  desired_frame->glyphs[vpos][used] = SPACEGLYPH;
		  desired_frame->glyphs[vpos][used] = 0;
		}
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	      bcopy (current_frame->glyphs[vpos] + end,
		     desired_frame->glyphs[vpos] + end,
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		     ((current_frame->used[vpos] - end)
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		      * sizeof (current_frame->glyphs[vpos][0])));
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	      bcopy (current_frame->charstarts[vpos] + end,
		     desired_frame->charstarts[vpos] + end,
		     ((current_frame->used[vpos] - end)
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		      * sizeof (current_frame->charstarts[vpos][0])));
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	      desired_frame->used[vpos] = current_frame->used[vpos];
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	    }
	}
    }
}

#if 0

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/* If window w does not need to be updated and isn't the full frame wide,
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 copy all the columns that w does occupy
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 into the FRAME_DESIRED_LINES (frame) from the FRAME_PHYS_LINES (frame)
 so that update_frame will not change those columns.
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 Have not been able to figure out how to use this correctly.  */

preserve_my_columns (w)
     struct window *w;
{
  register int vpos, fin;
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  register struct frame_glyphs *l1, *l2;
  register FRAME_PTR frame = XFRAME (w->frame);
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  int start = XFASTINT (w->left);
  int end = XFASTINT (w->left) + XFASTINT (w->width);
  int bot = XFASTINT (w->top) + XFASTINT (w->height);

  for (vpos = XFASTINT (w->top); vpos < bot; vpos++)
    {
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      if ((l1 = FRAME_DESIRED_GLYPHS (frame)->glyphs[vpos + 1])
	  && (l2 = FRAME_PHYS_GLYPHS (frame)->glyphs[vpos + 1]))
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	{
	  if (l2->length > start && l1->length < l2->length)
	    {
	      fin = l2->length;
	      if (fin > end) fin = end;
	      while (l1->length < start)
		l1->body[l1->length++] = ' ';
	      bcopy (l2->body + start, l1->body + start, fin - start);
	      l1->length = fin;
	    }
	}
    }
}

#endif

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/* Adjust by ADJUST the charstart values in window W
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   after vpos VPOS, which counts relative to the frame
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   (not relative to W itself).  */

void
adjust_window_charstarts (w, vpos, adjust)
     struct window *w;
     int vpos;
     int adjust;
{
  int left = XFASTINT (w->left);
  int top = XFASTINT (w->top);
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  int right = left + window_internal_width (w);
  int bottom = top + window_internal_height (w);
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  int i;

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  for (i = vpos + 1; i < bottom; i++)
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    {
      int *charstart
	= FRAME_CURRENT_GLYPHS (XFRAME (WINDOW_FRAME (w)))->charstarts[i];
      int j;
      for (j = left; j < right; j++)
	if (charstart[j] > 0)
	  charstart[j] += adjust;
    }
}
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/* Check the charstarts values in the area of window W
   for internal consistency.  We cannot check that they are "right";
   we can only look for something nonsensical.  */

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verify_charstarts (w)
     struct window *w;
{
  FRAME_PTR f = XFRAME (WINDOW_FRAME (w));
  int i;
  int top = XFASTINT (w->top);
  int bottom = top + window_internal_height (w);
  int left = XFASTINT (w->left);
  int right = left + window_internal_width (w);
  int next_line;
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  int truncate = (XINT (w->hscroll)
		  || (truncate_partial_width_windows
		      && (XFASTINT (w->width) < FRAME_WIDTH (f)))
		  || !NILP (XBUFFER (w->buffer)->truncate_lines));
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  for (i = top; i < bottom; i++)
    {
      int j;
      int last;
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      int *charstart = FRAME_CURRENT_GLYPHS (f)->charstarts[i];
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      if (i != top)
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	{
	  if (truncate)
	    {
	      /* If we are truncating lines, allow a jump
		 in charstarts from one line to the next.  */
	      if (charstart[left] < next_line)
		abort ();
	    }
	  else
	    {
	      if (charstart[left] != next_line)
		abort ();
	    }
	}
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      for (j = left; j < right; j++)
	if (charstart[j] > 0)
	  last = charstart[j];
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      /* Record where the next line should start.  */
      next_line = last;
      if (BUF_ZV (XBUFFER (w->buffer)) != last)
	{
	  /* If there's a newline between the two lines, count that.  */
	  int endchar = *BUF_CHAR_ADDRESS (XBUFFER (w->buffer), last);
	  if (endchar == '\n')
	    next_line++;
	}
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    }
}
1027

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/* On discovering that the redisplay for a window was no good,
   cancel the columns of that window, so that when the window is
   displayed over again get_display_line will not complain.  */

cancel_my_columns (w)
     struct window *w;
{
  register int vpos;
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  register struct frame_glyphs *desired_glyphs
    = FRAME_DESIRED_GLYPHS (XFRAME (w->frame));
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  register int start = XFASTINT (w->left);
  register int bot = XFASTINT (w->top) + XFASTINT (w->height);

  for (vpos = XFASTINT (w->top); vpos < bot; vpos++)
    if (desired_glyphs->enable[vpos]
	&& desired_glyphs->used[vpos] >= start)
      desired_glyphs->used[vpos] = start;
}

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/* These functions try to perform directly and immediately on the frame
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   the necessary output for one change in the buffer.
   They may return 0 meaning nothing was done if anything is difficult,
   or 1 meaning the output was performed properly.
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   They assume that the frame was up to date before the buffer
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   change being displayed.  They make various other assumptions too;
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