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/* MS-DOS specific C utilities.          -*- coding: raw-text -*-
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   Copyright (C) 1993, 94, 95, 96, 97, 1999 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
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the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */
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/* Contributed by Morten Welinder */
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/* New display, keyboard, and mouse control by Kim F. Storm */
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/* Note: some of the stuff here was taken from end of sysdep.c in demacs. */

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#include <config.h>
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#ifdef MSDOS
#include "lisp.h"
#include <stdio.h>
#include <stdlib.h>
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#include <time.h>
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#include <sys/param.h>
#include <sys/time.h>
#include <dos.h>
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#include <errno.h>
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#include <string.h>	 /* for bzero and string functions */
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#include <sys/stat.h>    /* for _fixpath */
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#include <unistd.h>	 /* for chdir, dup, dup2, etc. */
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#if __DJGPP__ >= 2
#include <fcntl.h>
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#include <io.h>		 /* for setmode */
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#include <dpmi.h>	 /* for __dpmi_xxx stuff */
#include <sys/farptr.h>	 /* for _farsetsel, _farnspokeb */
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#include <libc/dosio.h>  /* for _USE_LFN */
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#include <conio.h>	 /* for cputs */
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#endif

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#include "msdos.h"
#include "systime.h"
#include "termhooks.h"
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#include "termchar.h"
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#include "dispextern.h"
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#include "dosfns.h"
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#include "termopts.h"
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#include "charset.h"
#include "coding.h"
#include "disptab.h"
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#include "frame.h"
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#include "window.h"
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#include "buffer.h"
#include "commands.h"
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#include "blockinput.h"
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#include <go32.h>
#include <pc.h>
#include <ctype.h>
/* #include <process.h> */
/* Damn that local process.h!  Instead we can define P_WAIT ourselves.  */
#define P_WAIT 1

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#ifndef _USE_LFN
#define _USE_LFN 0
#endif

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#ifndef _dos_ds
#define _dos_ds _go32_info_block.selector_for_linear_memory
#endif

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#if __DJGPP__ > 1

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#include <signal.h>
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#include "syssignal.h"
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#ifndef SYSTEM_MALLOC

#ifdef GNU_MALLOC

/* If other `malloc' than ours is used, force our `sbrk' behave like
   Unix programs expect (resize memory blocks to keep them contiguous).
   If `sbrk' from `ralloc.c' is NOT used, also zero-out sbrk'ed memory,
   because that's what `gmalloc' expects to get.  */
#include <crt0.h>

#ifdef REL_ALLOC
int _crt0_startup_flags = _CRT0_FLAG_UNIX_SBRK;
#else  /* not REL_ALLOC */
int _crt0_startup_flags = (_CRT0_FLAG_UNIX_SBRK | _CRT0_FLAG_FILL_SBRK_MEMORY);
#endif /* not REL_ALLOC */
#endif /* GNU_MALLOC */

#endif /* not SYSTEM_MALLOC */
#endif /* __DJGPP__ > 1 */
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static unsigned long
event_timestamp ()
{
  struct time t;
  unsigned long s;
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  gettime (&t);
  s = t.ti_min;
  s *= 60;
  s += t.ti_sec;
  s *= 1000;
  s += t.ti_hund * 10;
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  return s;
}

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/* ------------------------ Mouse control ---------------------------
 *
 * Coordinates are in screen positions and zero based.
 * Mouse buttons are numbered from left to right and also zero based.
 */
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int have_mouse;          /* 0: no, 1: enabled, -1: disabled */
static int mouse_visible;
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static int mouse_last_x;
static int mouse_last_y;
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static int mouse_button_translate[NUM_MOUSE_BUTTONS];
static int mouse_button_count;
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void
mouse_on ()
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{
  union REGS regs;

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  if (have_mouse > 0 && !mouse_visible)
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    {
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      if (termscript)
	fprintf (termscript, "<M_ON>");
      regs.x.ax = 0x0001;
      int86 (0x33, &regs, &regs);
      mouse_visible = 1;
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    }
}

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void
mouse_off ()
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{
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  union REGS regs;
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  if (have_mouse > 0 && mouse_visible)
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    {
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      if (termscript)
	fprintf (termscript, "<M_OFF>");
      regs.x.ax = 0x0002;
      int86 (0x33, &regs, &regs);
      mouse_visible = 0;
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    }
}

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static void
mouse_get_xy (int *x, int *y)
{
  union REGS regs;

  regs.x.ax = 0x0003;
  int86 (0x33, &regs, &regs);
  *x = regs.x.cx / 8;
  *y = regs.x.dx / 8;
}

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void
mouse_moveto (x, y)
     int x, y;
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{
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  union REGS regs;
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  if (termscript)
    fprintf (termscript, "<M_XY=%dx%d>", x, y);
  regs.x.ax = 0x0004;
  mouse_last_x = regs.x.cx = x * 8;
  mouse_last_y = regs.x.dx = y * 8;
  int86 (0x33, &regs, &regs);
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}

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static int
mouse_pressed (b, xp, yp)
     int b, *xp, *yp;
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{
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  union REGS regs;
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  if (b >= mouse_button_count)
    return 0;
  regs.x.ax = 0x0005;
  regs.x.bx = mouse_button_translate[b];
  int86 (0x33, &regs, &regs);
  if (regs.x.bx)
    *xp = regs.x.cx / 8, *yp = regs.x.dx / 8;
  return (regs.x.bx != 0);
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}

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static int
mouse_released (b, xp, yp)
     int b, *xp, *yp;
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{
  union REGS regs;

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  if (b >= mouse_button_count)
    return 0;
  regs.x.ax = 0x0006;
  regs.x.bx = mouse_button_translate[b];
  int86 (0x33, &regs, &regs);
  if (regs.x.bx)
    *xp = regs.x.cx / 8, *yp = regs.x.dx / 8;
  return (regs.x.bx != 0);
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}

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static int
mouse_button_depressed (b, xp, yp)
     int b, *xp, *yp;
{
  union REGS regs;

  if (b >= mouse_button_count)
    return 0;
  regs.x.ax = 0x0003;
  int86 (0x33, &regs, &regs);
  if ((regs.x.bx & (1 << mouse_button_translate[b])) != 0)
    {
      *xp = regs.x.cx / 8;
      *yp = regs.x.dx / 8;
      return 1;
    }
  return 0;
}

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void
mouse_get_pos (f, insist, bar_window, part, x, y, time)
     FRAME_PTR *f;
     int insist;
     Lisp_Object *bar_window, *x, *y;
     enum scroll_bar_part *part;
     unsigned long *time;
{
  int ix, iy;
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  Lisp_Object frame, tail;

  /* Clear the mouse-moved flag for every frame on this display.  */
  FOR_EACH_FRAME (tail, frame)
    XFRAME (frame)->mouse_moved = 0;
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  *f = SELECTED_FRAME();
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  *bar_window = Qnil;
  mouse_get_xy (&ix, &iy);
  *time = event_timestamp ();
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  *x = make_number (mouse_last_x = ix);
  *y = make_number (mouse_last_y = iy);
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}
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static void
mouse_check_moved ()
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{
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  int x, y;
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  mouse_get_xy (&x, &y);
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  SELECTED_FRAME()->mouse_moved |= (x != mouse_last_x || y != mouse_last_y);
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  mouse_last_x = x;
  mouse_last_y = y;
}
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void
mouse_init ()
{
  union REGS regs;
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  int b;
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  if (termscript)
    fprintf (termscript, "<M_INIT>");
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  regs.x.ax = 0x0021;
  int86 (0x33, &regs, &regs);
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  /* Reset the mouse last press/release info.  It seems that Windows
     doesn't do that automatically when function 21h is called, which
     causes Emacs to ``remember'' the click that switched focus to the
     window just before Emacs was started from that window.  */
  for (b = 0; b < mouse_button_count; b++)
    {
      int dummy_x, dummy_y;

      (void) mouse_pressed (b, &dummy_x, &dummy_y);
      (void) mouse_released (b, &dummy_x, &dummy_y);
    }

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  regs.x.ax = 0x0007;
  regs.x.cx = 0;
  regs.x.dx = 8 * (ScreenCols () - 1);
  int86 (0x33, &regs, &regs);
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  regs.x.ax = 0x0008;
  regs.x.cx = 0;
  regs.x.dx = 8 * (ScreenRows () - 1);
  int86 (0x33, &regs, &regs);
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  mouse_moveto (0, 0);
  mouse_visible = 0;
}
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/* ------------------------- Screen control ----------------------
 *
 */
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static int internal_terminal = 0;
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#ifndef HAVE_X_WINDOWS
extern unsigned char ScreenAttrib;
static int screen_face;
static int highlight;
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static int screen_size_X;
static int screen_size_Y;
static int screen_size;
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static int current_pos_X;
static int current_pos_Y;
static int new_pos_X;
static int new_pos_Y;
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static void *startup_screen_buffer;
static int startup_screen_size_X;
static int startup_screen_size_Y;
static int startup_pos_X;
static int startup_pos_Y;
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static unsigned char startup_screen_attrib;
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static clock_t startup_time;

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static int term_setup_done;
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static unsigned short outside_cursor;

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/* Similar to the_only_frame.  */
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struct x_output the_only_x_display;
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/* Support for DOS/V (allows Japanese characters to be displayed on
   standard, non-Japanese, ATs).  Only supported for DJGPP v2 and later.  */

/* Holds the address of the text-mode screen buffer.  */
static unsigned long screen_old_address = 0;
/* Segment and offset of the virtual screen.  If 0, DOS/V is NOT loaded.  */
static unsigned short screen_virtual_segment = 0;
static unsigned short screen_virtual_offset = 0;
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/* A flag to control how to display unibyte 8-bit characters.  */
extern int unibyte_display_via_language_environment;
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Lisp_Object Qbar;

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#if __DJGPP__ > 1
/* Update the screen from a part of relocated DOS/V screen buffer which
   begins at OFFSET and includes COUNT characters.  */
static void
dosv_refresh_virtual_screen (int offset, int count)
{
  __dpmi_regs regs;

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  if (offset < 0 || count < 0)	/* paranoia; illegal values crash DOS/V */
    return;

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  regs.h.ah = 0xff;	/* update relocated screen */
  regs.x.es = screen_virtual_segment;
  regs.x.di = screen_virtual_offset + offset;
  regs.x.cx = count;
  __dpmi_int (0x10, &regs);
}
#endif

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static void
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dos_direct_output (y, x, buf, len)
     int y;
     int x;
     char *buf;
     int len;
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{
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  int t0 = 2 * (x + y * screen_size_X);
  int t = t0 + (int) ScreenPrimary;
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  int l0 = len;
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#if (__DJGPP__ < 2)
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  while (--len >= 0) {
    dosmemput (buf++, 1, t);
    t += 2;
  }
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#else
  /* This is faster.  */
  for (_farsetsel (_dos_ds); --len >= 0; t += 2, buf++)
    _farnspokeb (t, *buf);
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  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (t0, l0);
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#endif
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}
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#endif
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/* Flash the screen as a substitute for BEEPs.  */

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#if (__DJGPP__ < 2)
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static void
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do_visible_bell (xorattr)
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     unsigned char xorattr;
{
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  asm volatile
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    ("  movb   $1,%%dl
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visible_bell_0:
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	movl   _ScreenPrimary,%%eax
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	call   dosmemsetup
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	movl   %%eax,%%ebx
	movl   %1,%%ecx
	movb   %0,%%al
	incl   %%ebx
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visible_bell_1:
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	xorb   %%al,%%gs:(%%ebx)
	addl   $2,%%ebx
	decl   %%ecx
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	jne    visible_bell_1
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	decb   %%dl
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	jne    visible_bell_3
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visible_bell_2:
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	movzwl %%ax,%%eax
        movzwl %%ax,%%eax
	movzwl %%ax,%%eax
	movzwl %%ax,%%eax
	decw   %%cx
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	jne    visible_bell_2
	jmp    visible_bell_0
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visible_bell_3:"
     : /* no output */
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     : "m" (xorattr), "g" (screen_size)
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     : "%eax", "%ebx", /* "%gs",*/ "%ecx", "%edx");
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}

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static void
ScreenVisualBell (void)
{
  /* This creates an xor-mask that will swap the default fore- and
     background colors.  */
  do_visible_bell (((the_only_x_display.foreground_pixel
		     ^ the_only_x_display.background_pixel)
		    * 0x11) & 0x7f);
}
#endif

#ifndef HAVE_X_WINDOWS

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static int blink_bit = -1;	/* the state of the blink bit at startup */

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/* Enable bright background colors.  */
static void
bright_bg (void)
{
  union REGS regs;

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  /* Remember the original state of the blink/bright-background bit.
     It is stored at 0040:0065h in the BIOS data area.  */
  if (blink_bit == -1)
    blink_bit = (_farpeekb (_dos_ds, 0x465) & 0x20) == 0x20;

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  regs.h.bl = 0;
  regs.x.ax = 0x1003;
  int86 (0x10, &regs, &regs);
}

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/* Disable bright background colors (and enable blinking) if we found
   the video system in that state at startup.  */
static void
maybe_enable_blinking (void)
{
  if (blink_bit == 1)
    {
      union REGS regs;

      regs.h.bl = 1;
      regs.x.ax = 0x1003;
      int86 (0x10, &regs, &regs);
    }
}

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/* Return non-zero if the system has a VGA adapter.  */
static int
vga_installed (void)
{
  union REGS regs;

  regs.x.ax = 0x1a00;
  int86 (0x10, &regs, &regs);
  if (regs.h.al == 0x1a && regs.h.bl > 5 && regs.h.bl < 13)
    return 1;
  return 0;
}

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/* Set the screen dimensions so that it can show no less than
   ROWS x COLS frame.  */
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void
dos_set_window_size (rows, cols)
     int *rows, *cols;
{
  char video_name[30];
  Lisp_Object video_mode;
  int video_mode_value;
  int have_vga = 0;
  union REGS regs;
  int current_rows = ScreenRows (), current_cols = ScreenCols ();

  if (*rows == current_rows && *cols == current_cols)
    return;

  mouse_off ();
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  have_vga = vga_installed ();
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  /* If the user specified a special video mode for these dimensions,
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     use that mode.  */
  sprintf (video_name, "screen-dimensions-%dx%d", *rows, *cols);
  video_mode = XSYMBOL (Fintern_soft (build_string (video_name),
				      Qnil))-> value;

  if (INTEGERP (video_mode)
      && (video_mode_value = XINT (video_mode)) > 0)
    {
      regs.x.ax = video_mode_value;
      int86 (0x10, &regs, &regs);
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      if (have_mouse)
	{
	  /* Must hardware-reset the mouse, or else it won't update
	     its notion of screen dimensions for some non-standard
	     video modes.  This is *painfully* slow...  */
	  regs.x.ax = 0;
	  int86 (0x33, &regs, &regs);
	}
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    }

  /* Find one of the dimensions supported by standard EGA/VGA
     which gives us at least the required dimensions.  */

#if __DJGPP__ > 1

  else
    {
      static struct {
	int rows;
	int need_vga;
      }	std_dimension[] = {
	  {25, 0},
	  {28, 1},
	  {35, 0},
	  {40, 1},
	  {43, 0},
	  {50, 1}
      };
      int i = 0;

      while (i < sizeof (std_dimension) / sizeof (std_dimension[0]))
	{
	 if (std_dimension[i].need_vga <= have_vga
	     && std_dimension[i].rows >= *rows)
	   {
	     if (std_dimension[i].rows != current_rows
		 || *cols != current_cols)
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	       _set_screen_lines (std_dimension[i].rows);
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	     break;
	   }
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	 i++;
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	}
    }

#else /* not __DJGPP__ > 1 */

  else if (*rows <= 25)
    {
      if (current_rows != 25 || current_cols != 80)
	{
	  regs.x.ax = 3;
	  int86 (0x10, &regs, &regs);
	  regs.x.ax = 0x1101;
	  regs.h.bl = 0;
	  int86 (0x10, &regs, &regs);
	  regs.x.ax = 0x1200;
	  regs.h.bl = 32;
	  int86 (0x10, &regs, &regs);
	  regs.x.ax = 3;
	  int86 (0x10, &regs, &regs);
	}
    }
  else if (*rows <= 50)
    if (have_vga && (current_rows != 50 || current_cols != 80)
	|| *rows <= 43 && (current_rows != 43 || current_cols != 80))
      {
	regs.x.ax = 3;
	int86 (0x10, &regs, &regs);
	regs.x.ax = 0x1112;
	regs.h.bl = 0;
	int86 (0x10, &regs, &regs);
	regs.x.ax = 0x1200;
	regs.h.bl = 32;
	int86 (0x10, &regs, &regs);
	regs.x.ax = 0x0100;
	regs.x.cx = 7;
	int86 (0x10, &regs, &regs);
      }
#endif /* not __DJGPP__ > 1 */

  if (have_mouse)
    {
      mouse_init ();
      mouse_on ();
    }

  /* Tell the caller what dimensions have been REALLY set.  */
  *rows = ScreenRows ();
  *cols = ScreenCols ();
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#if __DJGPP__ > 1
  /* If the dimensions changed, the mouse highlight info is invalid.  */
  if (current_rows != *rows || current_cols != *cols)
    {
      struct frame *f = SELECTED_FRAME();
      struct display_info *dpyinfo = FRAME_X_DISPLAY_INFO (f);
      Lisp_Object window = dpyinfo->mouse_face_window;

      if (! NILP (window) && XFRAME (XWINDOW (window)->frame) == f)
	{
	  dpyinfo->mouse_face_beg_row = dpyinfo->mouse_face_beg_col = -1;
	  dpyinfo->mouse_face_end_row = dpyinfo->mouse_face_end_col = -1;
	  dpyinfo->mouse_face_window = Qnil;
	}
    }
#endif

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  /* Enable bright background colors.  */
  bright_bg ();
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  /* FIXME: I'm not sure the above will run at all on DOS/V.  But let's
     be defensive anyway.  */
  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (0, *cols * *rows);
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}

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/* If we write a character in the position where the mouse is,
   the mouse cursor may need to be refreshed.  */
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static void
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mouse_off_maybe ()
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{
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  int x, y;
  
  if (!mouse_visible)
    return;
  
  mouse_get_xy (&x, &y);
  if (y != new_pos_Y || x < new_pos_X)
    return;
  
  mouse_off ();
}

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#define DEFAULT_CURSOR_START (-1)
#define DEFAULT_CURSOR_WIDTH (-1)
#define BOX_CURSOR_WIDTH     (-32)

/* Set cursor to begin at scan line START_LINE in the character cell
   and extend for WIDTH scan lines.  Scan lines are counted from top
   of the character cell, starting from zero.  */
static void
msdos_set_cursor_shape (struct frame *f, int start_line, int width)
{
#if __DJGPP__ > 1
  unsigned desired_cursor;
  __dpmi_regs regs;
  int max_line, top_line, bot_line;

  /* Avoid the costly BIOS call if F isn't the currently selected
     frame.  Allow for NULL as unconditionally meaning the selected
     frame.  */
  if (f && f != SELECTED_FRAME())
    return;

  /* The character cell size in scan lines is stored at 40:85 in the
     BIOS data area.  */
  max_line = _farpeekw (_dos_ds, 0x485) - 1;
  switch (max_line)
    {
      default:	/* this relies on CGA cursor emulation being ON! */
      case 7:
	bot_line = 7;
	break;
      case 9:
	bot_line = 9;
	break;
      case 13:
	bot_line = 12;
	break;
      case 15:
	bot_line = 14;
	break;
    }

  if (width < 0)
    {
      if (width == BOX_CURSOR_WIDTH)
	{
	  top_line = 0;
	  bot_line = max_line;
	}
      else if (start_line != DEFAULT_CURSOR_START)
	{
	  top_line = start_line;
	  bot_line = top_line - width - 1;
	}
      else if (width != DEFAULT_CURSOR_WIDTH)
	{
	  top_line = 0;
	  bot_line = -1 - width;
	}
      else
	top_line = bot_line + 1;
    }
  else if (width == 0)
    {
      /* [31, 0] seems to DTRT for all screen sizes.  */
      top_line = 31;
      bot_line = 0;
    }
  else	/* WIDTH is positive */
    {
      if (start_line != DEFAULT_CURSOR_START)
	bot_line = start_line;
      top_line = bot_line - (width - 1);
    }

  /* If the current cursor shape is already what they want, we are
     history here.  */
  desired_cursor = ((top_line & 0x1f) << 8) | (bot_line & 0x1f);
  if (desired_cursor == _farpeekw (_dos_ds, 0x460))
    return;

  regs.h.ah = 1;
  regs.x.cx = desired_cursor;
  __dpmi_int (0x10, &regs);
#endif /* __DJGPP__ > 1 */
}

static void
IT_set_cursor_type (struct frame *f, Lisp_Object cursor_type)
{
  if (EQ (cursor_type, Qbar))
    {
      /* Just BAR means the normal EGA/VGA cursor.  */
      msdos_set_cursor_shape (f, DEFAULT_CURSOR_START, DEFAULT_CURSOR_WIDTH);
    }
  else if (CONSP (cursor_type) && EQ (XCAR (cursor_type), Qbar))
    {
      Lisp_Object bar_parms = XCDR (cursor_type);
      int width;

      if (INTEGERP (bar_parms))
	{
	  /* Feature: negative WIDTH means cursor at the top
	     of the character cell, zero means invisible cursor.  */
	  width = XINT (bar_parms);
	  msdos_set_cursor_shape (f, width >= 0 ? DEFAULT_CURSOR_START : 0,
				  width);
	}
      else if (CONSP (bar_parms)
	       && INTEGERP (XCAR (bar_parms))
	       && INTEGERP (XCDR (bar_parms)))
	{
	  int start_line = XINT (XCDR (bar_parms));

	  width = XINT (XCAR (bar_parms));
	  msdos_set_cursor_shape (f, start_line, width);
	}
    }
  else
    /* Treat anything unknown as "box cursor".  This includes nil, so
       that a frame which doesn't specify a cursor type gets a box,
       which is the default in Emacs.  */
    msdos_set_cursor_shape (f, 0, BOX_CURSOR_WIDTH);
}

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static void
IT_ring_bell (void)
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{
  if (visible_bell)
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    {
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      mouse_off ();
      ScreenVisualBell ();
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    }
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  else
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    {
      union REGS inregs, outregs;
      inregs.h.ah = 2;
      inregs.h.dl = 7;
      intdos (&inregs, &outregs);
    }
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}

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/* Given a face id FACE, extract the face parameters to be used for
   display until the face changes.  The face parameters (actually, its
   color) are used to construct the video attribute byte for each
   glyph during the construction of the buffer that is then blitted to
   the video RAM.  */
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static void
IT_set_face (int face)
{
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  struct frame *sf = SELECTED_FRAME();
  struct face *fp = FACE_FROM_ID (sf, face);
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  unsigned long fg, bg;
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  if (!fp)
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    {
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      fp = FACE_FROM_ID (sf, DEFAULT_FACE_ID);
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      /* The default face for the frame should always be realized and
	 cached.  */
      if (!fp)
	abort ();
    }
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  screen_face = face;
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  fg = fp->foreground;
  bg = fp->background;

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  /* Don't use invalid colors.  In particular, FACE_TTY_DEFAULT_*
     colors mean use the colors of the default face, except that if
     highlight is on, invert the foreground and the background.  Note
     that we assume all 16 colors to be available for the background,
     since Emacs switches on this mode (and loses the blinking
     attribute) at startup.  */
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  if (fg == FACE_TTY_DEFAULT_COLOR || fg == FACE_TTY_DEFAULT_FG_COLOR)
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    fg = FRAME_FOREGROUND_PIXEL (sf);
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  else if (fg == FACE_TTY_DEFAULT_BG_COLOR)
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    fg = FRAME_BACKGROUND_PIXEL (sf);
  if (bg == FACE_TTY_DEFAULT_COLOR || bg == FACE_TTY_DEFAULT_BG_COLOR)
    bg = FRAME_BACKGROUND_PIXEL (sf);
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  else if (bg == FACE_TTY_DEFAULT_FG_COLOR)
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    bg = FRAME_FOREGROUND_PIXEL (sf);

  /* Make sure highlighted lines really stand out, come what may.  */
  if ((highlight || fp->tty_reverse_p)
      && (fg == FRAME_FOREGROUND_PIXEL (sf)
	  && bg == FRAME_BACKGROUND_PIXEL (sf)))
    {
      unsigned long tem = fg;

      fg = bg;
      bg = tem;
    }
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  if (termscript)
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    fprintf (termscript, "<FACE %d%s: %d/%d[FG:%d/BG:%d]>", face,
	     highlight ? "H" : "", fp->foreground, fp->background, fg, bg);
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  if (fg >= 0 && fg < 16)
    {
      ScreenAttrib &= 0xf0;
      ScreenAttrib |= fg;
    }
  if (bg >= 0 && bg < 16)
    {
      ScreenAttrib &= 0x0f;
      ScreenAttrib |= ((bg & 0x0f) << 4);
    }
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}

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Lisp_Object Vdos_unsupported_char_glyph;

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static void
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IT_write_glyphs (struct glyph *str, int str_len)
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{
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  unsigned char *screen_buf, *screen_bp, *screen_buf_end, *bp;
  int unsupported_face = FAST_GLYPH_FACE (Vdos_unsupported_char_glyph);
  unsigned unsupported_char= FAST_GLYPH_CHAR (Vdos_unsupported_char_glyph);
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  int offset = 2 * (new_pos_X + screen_size_X * new_pos_Y);
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  register int sl = str_len;
  register int tlen = GLYPH_TABLE_LENGTH;
  register Lisp_Object *tbase = GLYPH_TABLE_BASE;

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  struct coding_system *coding = (CODING_REQUIRE_ENCODING (&terminal_coding)
				  ? &terminal_coding
				  : &safe_terminal_coding);
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  struct frame *sf;
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  /* Do we need to consider conversion of unibyte characters to
     multibyte?  */
  int convert_unibyte_characters
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    = (NILP (current_buffer->enable_multibyte_characters)
       && unibyte_display_via_language_environment);
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  if (str_len <= 0) return;
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  screen_buf = screen_bp = alloca (str_len * 2);
  screen_buf_end = screen_buf + str_len * 2;
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  sf = SELECTED_FRAME();
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  /* Since faces get cached and uncached behind our back, we can't
     rely on their indices in the cache being consistent across
     invocations.  So always reset the screen face to the default
     face of the frame, before writing glyphs, and let the glyphs
     set the right face if it's different from the default.  */
  IT_set_face (DEFAULT_FACE_ID);
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  /* The mode bit CODING_MODE_LAST_BLOCK should be set to 1 only at
     the tail.  */
  terminal_coding.mode &= ~CODING_MODE_LAST_BLOCK;
  while (sl)
    {
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      int cf, chlen, enclen;
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      unsigned char workbuf[MAX_MULTIBYTE_LENGTH], *buf;
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      unsigned ch;
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      /* Glyphs with GLYPH_MASK_PADDING bit set are actually there
	 only for the redisplay code to know how many columns does
         this character occupy on the screen.  Skip padding glyphs.  */
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      if (CHAR_GLYPH_PADDING_P (*str))
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	{
	  str++;
	  sl--;
	}
      else
	{
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	  register GLYPH g = GLYPH_FROM_CHAR_GLYPH (*str);
	  int glyph_not_in_table = 0;

	  if (g < 0 || g >= tlen)
	    {
	      /* This glyph doesn't have an entry in Vglyph_table.  */
	      ch = str->u.ch;
	      glyph_not_in_table = 1;
	    }
	  else
	    {
	      /* This glyph has an entry in Vglyph_table, so process
		 any aliases before testing for simpleness.  */
	      GLYPH_FOLLOW_ALIASES (tbase, tlen, g);
	      ch = FAST_GLYPH_CHAR (g);
	    }

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	  /* Convert the character code to multibyte, if they
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	     requested display via language environment.  We only want
	     to convert unibyte characters to multibyte in unibyte
	     buffers!  Otherwise, the 8-bit value in CH came from the
	     display table set up to display foreign characters.  */
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	  if (SINGLE_BYTE_CHAR_P (ch) && convert_unibyte_characters
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	      && (ch >= 0240
		  || (ch >= 0200 && !NILP (Vnonascii_translation_table))))
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	    ch = unibyte_char_to_multibyte (ch);

	  /* Invalid characters are displayed with a special glyph.  */
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	  if (! CHAR_VALID_P (ch, 0))
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	    {
	      g = !NILP (Vdos_unsupported_char_glyph)
		? Vdos_unsupported_char_glyph
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		: MAKE_GLYPH (sf, '\177', GLYPH_FACE (sf, g));
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	      ch = FAST_GLYPH_CHAR (g);
	    }

	  /* If the face of this glyph is different from the current
	     screen face, update the screen attribute byte.  */
	  cf = FAST_GLYPH_FACE (g);
	  if (cf != screen_face)
	    IT_set_face (cf);	/* handles invalid faces gracefully */

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	  if (glyph_not_in_table || GLYPH_SIMPLE_P (tbase, tlen, g))
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	    {
	      /* We generate the multi-byte form of CH in WORKBUF.  */
	      chlen = CHAR_STRING (ch, workbuf);
	      buf = workbuf;
	    }
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	  else
	    {
	      /* We have a string in Vglyph_table.  */
	      chlen = GLYPH_LENGTH (tbase, g);
	      buf = GLYPH_STRING (tbase, g);
	    }

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	  /* If the character is not multibyte, don't bother converting it.  */
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	  if (chlen == 1)
	    {
	      *conversion_buffer = (unsigned char)ch;
	      chlen = 0;
	      enclen = 1;
	    }
	  else
	    {
	      encode_coding (coding, buf, conversion_buffer, chlen,
			     conversion_buffer_size);
	      chlen -= coding->consumed;
	      enclen = coding->produced;

	      /* Replace glyph codes that cannot be converted by
		 terminal_coding with Vdos_unsupported_char_glyph.  */
	      if (*conversion_buffer == '?')
		{
		  char *cbp = conversion_buffer;

		  while (cbp < conversion_buffer + enclen && *cbp == '?')
		    *cbp++ = unsupported_char;
		  if (unsupported_face != screen_face)
		    IT_set_face (unsupported_face);
		}
	    }

	  if (enclen + chlen > screen_buf_end - screen_bp)
	    {
	      /* The allocated buffer for screen writes is too small.
		 Flush it and loop again without incrementing STR, so
		 that the next loop will begin with the same glyph.  */
	      int nbytes = screen_bp - screen_buf;

	      mouse_off_maybe ();
	      dosmemput (screen_buf, nbytes, (int)ScreenPrimary + offset);
	      if (screen_virtual_segment)
		dosv_refresh_virtual_screen (offset, nbytes / 2);
	      new_pos_X += nbytes / 2;
	      offset += nbytes;

	      /* Prepare to reuse the same buffer again.  */
	      screen_bp = screen_buf;
	    }
	  else
	    {
	      /* There's enough place in the allocated buffer to add
		 the encoding of this glyph.  */

	      /* First, copy the encoded bytes.  */
	      for (bp = conversion_buffer; enclen--; bp++)
		{
		  *screen_bp++ = (unsigned char)*bp;
		  *screen_bp++ = ScreenAttrib;
		  if (termscript)
		    fputc (*bp, termscript);
		}

	      /* Now copy the bytes not consumed by the encoding.  */
	      if (chlen > 0)
		{
		  buf += coding->consumed;
		  while (chlen--)
		    {
		      if (termscript)
			fputc (*buf, termscript);
		      *screen_bp++ = (unsigned char)*buf++;
		      *screen_bp++ = ScreenAttrib;
		    }
		}

	      /* Update STR and its remaining length.  */
	      str++;
	      sl--;
	    }
	}
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    }

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  /* Dump whatever is left in the screen buffer.  */
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  mouse_off_maybe ();
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  dosmemput (screen_buf, screen_bp - screen_buf, (int)ScreenPrimary + offset);
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  if (screen_virtual_segment)
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    dosv_refresh_virtual_screen (offset, (screen_bp - screen_buf) / 2);
  new_pos_X += (screen_bp - screen_buf) / 2;

  /* We may have to output some codes to terminate the writing.  */
  if (CODING_REQUIRE_FLUSHING (coding))
    {
      coding->mode |= CODING_MODE_LAST_BLOCK;
      encode_coding (coding, "", conversion_buffer, 0, conversion_buffer_size);
      if (coding->produced > 0)
	{
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	  screen_buf = alloca (coding->produced * 2);
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	  for (screen_bp = screen_buf, bp = conversion_buffer;
	       coding->produced--; bp++)
	    {
	      *screen_bp++ = (unsigned char)*bp;
	      *screen_bp++ = ScreenAttrib;
	      if (termscript)
		fputc (*bp, termscript);
	    }
	  offset += screen_bp - screen_buf;
	  mouse_off_maybe ();
	  dosmemput (screen_buf, screen_bp - screen_buf,
		     (int)ScreenPrimary + offset);
	  if (screen_virtual_segment)
	    dosv_refresh_virtual_screen (offset, (screen_bp - screen_buf) / 2);
	  new_pos_X += (screen_bp - screen_buf) / 2;
	}
    }
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}
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/************************************************************************
			  Mouse Highlight (and friends..)
 ************************************************************************/

/* This is used for debugging, to turn off note_mouse_highlight.  */
int disable_mouse_highlight;

/* If a string, dos_rawgetc generates an event to display that string.
   (The display is done in keyboard.c:read_char.)  */
static Lisp_Object help_echo;
static Lisp_Object previous_help_echo; /* a helper temporary variable */

static int mouse_preempted = 0;	/* non-zero when XMenu gobbles mouse events */

/* Set the mouse pointer shape according to whether it is in the
   area where the mouse highlight is in effect.  */
static void
IT_set_mouse_pointer (int mode)
{
  /* A no-op for now.  DOS text-mode mouse pointer doesn't offer too
     many possibilities to change its shape, and the available
     functionality pretty much sucks (e.g., almost every reasonable
     shape will conceal the character it is on).  Since the color of
     the pointer changes in the highlighted area, it is not clear to
     me whether anything else is required, anyway.  */
}

/* Display the active region described by mouse_face_*
   in its mouse-face if HL > 0, in its normal face if HL = 0.  */
static void
show_mouse_face (struct display_info *dpyinfo, int hl)
{
  struct window *w = XWINDOW (dpyinfo->mouse_face_window);
  struct frame *f = XFRAME (WINDOW_FRAME (w));
  int i;
  struct face *fp;

  
  /* If window is in the process of being destroyed, don't bother
     doing anything.  */
  if (w->current_matrix == NULL)
    goto set_cursor_shape;

  /* Recognize when we are called to operate on rows that don't exist
     anymore.  This can happen when a window is split.  */
  if (dpyinfo->mouse_face_end_row >= w->current_matrix->nrows)
    goto set_cursor_shape;

  /* There's no sense to do anything if the mouse face isn't realized.  */
  if (hl > 0)
    {
      fp = FACE_FROM_ID (SELECTED_FRAME(), dpyinfo->mouse_face_face_id);
      if (!fp)
	goto set_cursor_shape;
    }

  /* Note that mouse_face_beg_row etc. are window relative.  */
  for (i = dpyinfo->mouse_face_beg_row;
       i <= dpyinfo->mouse_face_end_row;
       i++)
    {
      int start_hpos, end_hpos;
      struct glyph_row *row = MATRIX_ROW (w->current_matrix, i);

      /* Don't do anything if row doesn't have valid contents.  */
      if (!row->enabled_p)
	continue;

      /* For all but the first row, the highlight starts at column 0.  */
      if (i == dpyinfo->mouse_face_beg_row)
	start_hpos = dpyinfo->mouse_face_beg_col;
      else
	start_hpos = 0;

      if (i == dpyinfo->mouse_face_end_row)
	end_hpos = dpyinfo->mouse_face_end_col;
      else
	end_hpos = row->used[TEXT_AREA];

      if (end_hpos <= start_hpos)
	continue;
      if (hl > 0)
	{
	  int vpos = row->y + WINDOW_DISPLAY_TOP_EDGE_PIXEL_Y (w);
	  int kstart = start_hpos + WINDOW_DISPLAY_LEFT_EDGE_PIXEL_X (w);
	  int nglyphs = end_hpos - start_hpos;
	  int offset = ScreenPrimary + 2*(vpos*screen_size_X + kstart) + 1;
	  int start_offset = offset;

	  if (termscript)
	    fprintf (termscript, "\n<MH+ %d-%d:%d>",
		     kstart, kstart + nglyphs - 1, vpos);

	  mouse_off ();
	  IT_set_face (dpyinfo->mouse_face_face_id);
	  /* Since we are going to change only the _colors_ of the
	     displayed text, there's no need to go through all the
	     pain of generating and encoding the text from the glyphs.
	     Instead, we simply poke the attribute byte of each
	     affected position in video memory with the colors
	     computed by IT_set_face!  */
	  _farsetsel (_dos_ds);
	  while (nglyphs--)
	    {
	      _farnspokeb (offset, ScreenAttrib);
	      offset += 2;
	    }
	  if (screen_virtual_segment)
	    dosv_refresh_virtual_screen (start_offset, end_hpos - start_hpos);
	  mouse_on ();
	}
      else
	{
	  /* We are removing a previously-drawn mouse highlight.  The
	     safest way to do so is to redraw the glyphs anew, since
	     all kinds of faces and display tables could have changed
	     behind our back.  */
	  int nglyphs = end_hpos - start_hpos;
	  int save_x = new_pos_X, save_y = new_pos_Y;

	  if (end_hpos >= row->used[TEXT_AREA])
	    nglyphs = row->used[TEXT_AREA] - start_hpos;

	  /* IT_write_glyphs writes at cursor position, so we need to
	     temporarily move cursor coordinates to the beginning of
	     the highlight region.  */
	  new_pos_X = start_hpos + WINDOW_DISPLAY_LEFT_EDGE_PIXEL_X (w);
	  new_pos_Y = row->y + WINDOW_DISPLAY_TOP_EDGE_PIXEL_Y (w);

	  if (termscript)
	    fprintf (termscript, "<MH- %d-%d:%d>",
		     new_pos_X, new_pos_X + nglyphs - 1, new_pos_Y);
	  IT_write_glyphs (row->glyphs[TEXT_AREA] + start_hpos, nglyphs);
	  if (termscript)
	    fputs ("\n", termscript);
	  new_pos_X = save_x;
	  new_pos_Y = save_y;
	}
    }

 set_cursor_shape:
  
  /* Change the mouse pointer shape.  */
  IT_set_mouse_pointer (hl);
}

/* Clear out the mouse-highlighted active region.
   Redraw it un-highlighted first.  */
static void
clear_mouse_face (struct display_info *dpyinfo)
{
  if (! NILP (dpyinfo->mouse_face_window))
    show_mouse_face (dpyinfo, 0);

  dpyinfo->mouse_face_beg_row = dpyinfo->mouse_face_beg_col = -1;
  dpyinfo->mouse_face_end_row = dpyinfo->mouse_face_end_col = -1;
  dpyinfo->mouse_face_window = Qnil;
}

/* Find the glyph matrix position of buffer position POS in window W.
   *HPOS and *VPOS are set to the positions found.  W's current glyphs
   must be up to date.  If POS is above window start return (0, 0).
   If POS is after end of W, return end of last line in W.  */
static int
fast_find_position (struct window *w, int pos, int *hpos, int *vpos)
{
  int i;
  int lastcol;
  int maybe_next_line_p = 0;
  int line_start_position;
  int yb = window_text_bottom_y (w);
  struct glyph_row *row = MATRIX_ROW (w->current_matrix, 0);
  struct glyph_row *best_row = row;

  while (row->y < yb)
    {
      if (row->used[TEXT_AREA])
	line_start_position = row->glyphs[TEXT_AREA]->charpos;
      else
	line_start_position = 0;

      if (line_start_position > pos)
	break;
      /* If the position sought is the end of the buffer,
	 don't include the blank lines at the bottom of the window.  */
      else if (line_start_position == pos
	       && pos == BUF_ZV (XBUFFER (w->buffer)))
	{
	  maybe_next_line_p = 1;
	  break;
	}
      else if (line_start_position > 0)
	best_row = row;
      
      ++row;
    }
  
  /* Find the right column within BEST_ROW.  */
  lastcol = 0;
  row = best_row;
  for (i = 0; i < row->used[TEXT_AREA]; i++)
    {
      struct glyph *glyph = row->glyphs[TEXT_AREA] + i;
      int charpos;

      charpos = glyph->charpos;
      if (charpos == pos)
	{
	  *hpos = i;
	  *vpos = row->y;
	  return 1;
	}
      else if (charpos > pos)
	break;
      else if (charpos > 0)
	lastcol = i;
    }

  /* If we're looking for the end of the buffer,
     and we didn't find it in the line we scanned,
     use the start of the following line.  */
  if (maybe_next_line_p)
    {
      ++row;
      lastcol = 0;
    }

  *vpos = row->y;
  *hpos = lastcol + 1;
  return 0;
}

/* Take proper action when mouse has moved to the mode or top line of
   window W, x-position X.  MODE_LINE_P non-zero means mouse is on the
   mode line.  X is relative to the start of the text display area of
   W, so the width of bitmap areas and scroll bars must be subtracted
   to get a position relative to the start of the mode line.  */
static void
IT_note_mode_line_highlight (struct window *w, int x, int mode_line_p)
{
  struct frame *f = XFRAME (w->frame);
  struct display_info *dpyinfo = FRAME_X_DISPLAY_INFO (f);
  struct glyph_row *row;

  if (mode_line_p)
    row = MATRIX_MODE_LINE_ROW (w->current_matrix);
  else
    row = MATRIX_HEADER_LINE_ROW (w->current_matrix);
  
  if (row->enabled_p)
    {
      extern Lisp_Object Qhelp_echo;
      struct glyph *glyph, *end;
      Lisp_Object help, map;
      
      /* Find the glyph under X.  */
      glyph = row->glyphs[TEXT_AREA]
	+ x - FRAME_LEFT_SCROLL_BAR_WIDTH (f) * CANON_X_UNIT (f);
      end = glyph + row->used[TEXT_AREA];
      if (glyph < end
	  && STRINGP (glyph->object)
	  && XSTRING (glyph->object)->intervals
	  && glyph->charpos >= 0
	  && glyph->charpos < XSTRING (glyph->object)->size)
	{
	  /* If we're on a string with `help-echo' text property,
	     arrange for the help to be displayed.  This is done by
	     setting the global variable help_echo to the help string.  */
	  help = Fget_text_property (make_number (glyph->charpos),
				     Qhelp_echo, glyph->object);
	  if (STRINGP (help))
	    help_echo = help;
	}
    }
}