(w32_draw_fringe_bitmap): Copy unadapted code from

[bpt/emacs.git] / src / msdos.c

/* MS-DOS specific C utilities.          -*- coding: raw-text -*-
   Copyright (C) 1993, 94, 95, 96, 97, 1999, 2000, 01, 2003
   Free Software Foundation, Inc.

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
the Free Software Foundation; either version 2, or (at your option)
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, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* Contributed by Morten Welinder */
/* New display, keyboard, and mouse control by Kim F. Storm */

/* Note: some of the stuff here was taken from end of sysdep.c in demacs. */

#include <config.h>

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

#include "msdos.h"
#include "systime.h"
#include "termhooks.h"
#include "termchar.h"
#include "dispextern.h"
#include "dosfns.h"
#include "termopts.h"
#include "charset.h"
#include "coding.h"
#include "disptab.h"
#include "frame.h"
#include "window.h"
#include "buffer.h"
#include "commands.h"
#include "blockinput.h"
#include "keyboard.h"
#include "intervals.h"
#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

#ifndef _USE_LFN
#define _USE_LFN 0
#endif

#ifndef _dos_ds
#define _dos_ds _go32_info_block.selector_for_linear_memory
#endif

#if __DJGPP__ > 1

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

#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 */

static unsigned long
event_timestamp ()
{
  struct time t;
  unsigned long s;

  gettime (&t);
  s = t.ti_min;
  s *= 60;
  s += t.ti_sec;
  s *= 1000;
  s += t.ti_hund * 10;

  return s;
}

\f
/* ------------------------ Mouse control ---------------------------
 *
 * Coordinates are in screen positions and zero based.
 * Mouse buttons are numbered from left to right and also zero based.
 */

/* This used to be in termhooks.h, but mainstream Emacs code no longer
   uses it, and it was removed...  */
#define NUM_MOUSE_BUTTONS (5)

int have_mouse;          /* 0: no, 1: enabled, -1: disabled */
static int mouse_visible;

static int mouse_last_x;
static int mouse_last_y;

static int mouse_button_translate[NUM_MOUSE_BUTTONS];
static int mouse_button_count;

void
mouse_on ()
{
  union REGS regs;

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

void
mouse_off ()
{
  union REGS regs;

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

static void
mouse_setup_buttons (int n_buttons)
{
  if (n_buttons == 3)
    {
      mouse_button_count = 3;
      mouse_button_translate[0] = 0; /* Left */
      mouse_button_translate[1] = 2; /* Middle */
      mouse_button_translate[2] = 1; /* Right */
    }
  else	/* two, what else? */
    {
      mouse_button_count = 2;
      mouse_button_translate[0] = 0;
      mouse_button_translate[1] = 1;
    }
}

DEFUN ("msdos-set-mouse-buttons", Fmsdos_set_mouse_buttons, Smsdos_set_mouse_buttons,
       1, 1, "NSet number of mouse buttons to: ",
       doc: /* Set the number of mouse buttons to use by Emacs.
This is useful with mice that report the number of buttons inconsistently,
e.g., if the number of buttons is reported as 3, but Emacs only sees 2 of
them.  This happens with wheeled mice on Windows 9X, for example.  */)
     (nbuttons)
     Lisp_Object nbuttons;
{
  int n;

  CHECK_NUMBER (nbuttons);
  n = XINT (nbuttons);
  if (n < 2 || n > 3)
    Fsignal (Qargs_out_of_range,
	     Fcons (build_string ("only 2 or 3 mouse buttons are supported"),
		    Fcons (nbuttons, Qnil)));
  mouse_setup_buttons (n);
  return Qnil;
}

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;
}

void
mouse_moveto (x, y)
     int x, y;
{
  union REGS regs;

  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);
}

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

  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);
}

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

  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);
}

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;
}

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;
  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;

  *f = SELECTED_FRAME();
  *bar_window = Qnil;
  mouse_get_xy (&ix, &iy);
  *time = event_timestamp ();
  *x = make_number (mouse_last_x = ix);
  *y = make_number (mouse_last_y = iy);
}

static void
mouse_check_moved ()
{
  int x, y;

  mouse_get_xy (&x, &y);
  SELECTED_FRAME()->mouse_moved |= (x != mouse_last_x || y != mouse_last_y);
  mouse_last_x = x;
  mouse_last_y = y;
}

/* Force the mouse driver to ``forget'' about any button clicks until
   now.  */
static void
mouse_clear_clicks (void)
{
  int b;

  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);
    }
}

void
mouse_init ()
{
  union REGS regs;

  if (termscript)
    fprintf (termscript, "<M_INIT>");

  regs.x.ax = 0x0021;
  int86 (0x33, &regs, &regs);

  /* 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.  */
  mouse_clear_clicks ();

  regs.x.ax = 0x0007;
  regs.x.cx = 0;
  regs.x.dx = 8 * (ScreenCols () - 1);
  int86 (0x33, &regs, &regs);

  regs.x.ax = 0x0008;
  regs.x.cx = 0;
  regs.x.dx = 8 * (ScreenRows () - 1);
  int86 (0x33, &regs, &regs);

  mouse_moveto (0, 0);
  mouse_visible = 0;
}
\f
/* ------------------------- Screen control ----------------------
 *
 */

static int internal_terminal = 0;

#ifndef HAVE_X_WINDOWS
extern unsigned char ScreenAttrib;
static int screen_face;

static int screen_size_X;
static int screen_size_Y;
static int screen_size;

static int current_pos_X;
static int current_pos_Y;
static int new_pos_X;
static int new_pos_Y;

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;
static unsigned char startup_screen_attrib;

static clock_t startup_time;

static int term_setup_done;

static unsigned short outside_cursor;

/* Similar to the_only_frame.  */
struct x_output the_only_x_display;

/* 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;
/* A flag to control how to display unibyte 8-bit characters.  */
extern int unibyte_display_via_language_environment;

extern Lisp_Object Qcursor_type;
extern Lisp_Object Qbar, Qhbar;

/* The screen colors of the current frame, which serve as the default
   colors for newly-created frames.  */
static int initial_screen_colors[2];

#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;

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

  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

static void
dos_direct_output (y, x, buf, len)
     int x, y;
     char *buf;
     int len;
{
  int t0 = 2 * (x + y * screen_size_X);
  int t = t0 + (int) ScreenPrimary;
  int l0 = len;

#if (__DJGPP__ < 2)
  while (--len >= 0) {
    dosmemput (buf++, 1, t);
    t += 2;
  }
#else
  /* This is faster.  */
  for (_farsetsel (_dos_ds); --len >= 0; t += 2, buf++)
    _farnspokeb (t, *buf);

  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (t0, l0);
#endif
}
#endif

/* Flash the screen as a substitute for BEEPs.  */

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

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

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

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

  /* 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;

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

/* 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);
    }
}

/* 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;
}

/* Set the screen dimensions so that it can show no less than
   ROWS x COLS frame.  */

void
dos_set_window_size (rows, cols)
     int *rows, *cols;
{
  char video_name[30];
  union REGS regs;
  Lisp_Object video_mode;
  int video_mode_value, have_vga = 0;
  int current_rows = ScreenRows (), current_cols = ScreenCols ();

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

  mouse_off ();
  have_vga = vga_installed ();

  /* If the user specified a special video mode for these dimensions,
     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);

      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);
	}
    }

  /* 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, 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)
	       _set_screen_lines (std_dimension[i].rows);
	     break;
	   }
	 i++;
	}
    }

#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 ();

  /* Update Emacs' notion of screen dimensions.  */
  screen_size_X = *cols;
  screen_size_Y = *rows;
  screen_size = *cols * *rows;

#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

  /* Enable bright background colors.  */
  bright_bg ();

  /* 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);
}

/* If we write a character in the position where the mouse is,
   the mouse cursor may need to be refreshed.  */

static void
mouse_off_maybe ()
{
  int x, y;

  if (!mouse_visible)
    return;

  mouse_get_xy (&x, &y);
  if (y != new_pos_Y || x < new_pos_X)
    return;

  mouse_off ();
}

#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) || EQ (cursor_type, Qhbar))
    {
      /* 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)
	       || EQ (XCAR (cursor_type), Qhbar)))
    {
      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);
}

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

/* 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.  */
static void
IT_set_face (int face)
{
  struct frame *sf = SELECTED_FRAME();
  struct face *fp  = FACE_FROM_ID (sf, face);
  struct face *dfp = FACE_FROM_ID (sf, DEFAULT_FACE_ID);
  unsigned long fg, bg, dflt_fg, dflt_bg;

  if (!fp)
    {
      fp = dfp;
      /* The default face for the frame should always be realized and
	 cached.  */
      if (!fp)
	abort ();
    }
  screen_face = face;
  fg = fp->foreground;
  bg = fp->background;
  dflt_fg = dfp->foreground;
  dflt_bg = dfp->background;

  /* Don't use invalid colors.  In particular, FACE_TTY_DEFAULT_* colors
     mean use the colors of the default face.  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.  */
  if (fg == FACE_TTY_DEFAULT_COLOR || fg == FACE_TTY_DEFAULT_FG_COLOR)
    fg = FRAME_FOREGROUND_PIXEL (sf);
  else if (fg == FACE_TTY_DEFAULT_BG_COLOR)
    fg = FRAME_BACKGROUND_PIXEL (sf);
  if (bg == FACE_TTY_DEFAULT_COLOR || bg == FACE_TTY_DEFAULT_BG_COLOR)
    bg = FRAME_BACKGROUND_PIXEL (sf);
  else if (bg == FACE_TTY_DEFAULT_FG_COLOR)
    bg = FRAME_FOREGROUND_PIXEL (sf);

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

      fg = bg;
      bg = tem;
    }
  /* If the user requested inverse video, obey.  */
  if (inverse_video)
    {
      unsigned long tem2 = fg;

      fg = bg;
      bg = tem2;
    }
  if (termscript)
    fprintf (termscript, "<FACE %d: %d/%d[FG:%d/BG:%d]>", face,
	     fp->foreground, fp->background, fg, bg);
  if (fg >= 0 && fg < 16)
    {
      ScreenAttrib &= 0xf0;
      ScreenAttrib |= fg;
    }
  if (bg >= 0 && bg < 16)
    {
      ScreenAttrib &= 0x0f;
      ScreenAttrib |= ((bg & 0x0f) << 4);
    }
}

Lisp_Object Vdos_unsupported_char_glyph;

static void
IT_write_glyphs (struct glyph *str, int str_len)
{
  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);
  int offset = 2 * (new_pos_X + screen_size_X * new_pos_Y);
  register int sl = str_len;
  register int tlen = GLYPH_TABLE_LENGTH;
  register Lisp_Object *tbase = GLYPH_TABLE_BASE;

  /* If terminal_coding does any conversion, use it, otherwise use
     safe_terminal_coding.  We can't use CODING_REQUIRE_ENCODING here
     because it always returns 1 if terminal_coding.src_multibyte is 1.  */
  struct coding_system *coding =
    (terminal_coding.common_flags & CODING_REQUIRE_ENCODING_MASK
     ? &terminal_coding
     : &safe_terminal_coding);
  struct frame *sf;

  /* Do we need to consider conversion of unibyte characters to
     multibyte?  */
  int convert_unibyte_characters
    = (NILP (current_buffer->enable_multibyte_characters)
       && unibyte_display_via_language_environment);

  unsigned char conversion_buffer[256];
  int conversion_buffer_size = sizeof conversion_buffer;

  if (str_len <= 0) return;

  screen_buf = screen_bp = alloca (str_len * 2);
  screen_buf_end = screen_buf + str_len * 2;
  sf = SELECTED_FRAME();

  /* 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);

  /* 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)
    {
      int cf, chlen, enclen;
      unsigned char workbuf[MAX_MULTIBYTE_LENGTH], *buf;
      unsigned ch;

      /* 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.  */
      if (CHAR_GLYPH_PADDING_P (*str))
	{
	  str++;
	  sl--;
	}
      else
	{
	  register GLYPH g = GLYPH_FROM_CHAR_GLYPH (*str);
	  int glyph_not_in_table = 0;

	  /* If g is negative, it means we have a multibyte character
	     in *str.  That's what GLYPH_FROM_CHAR_GLYPH returns for
	     multibyte characters.  */
	  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);
	    }

	  /* Convert the character code to multibyte, if they
	     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.  */
	  if (SINGLE_BYTE_CHAR_P (ch) && convert_unibyte_characters
	      && (ch >= 0240
		  || (ch >= 0200 && !NILP (Vnonascii_translation_table))))
	    ch = unibyte_char_to_multibyte (ch);

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

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

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

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

  /* Dump whatever is left in the screen buffer.  */
  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;

  /* 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)
	{
	  screen_buf = alloca (coding->produced * 2);
	  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;
	}
    }
}

/************************************************************************
			  Mouse Highlight (and friends..)
 ************************************************************************/

/* Last window where we saw the mouse.  Used by mouse-autoselect-window.  */
static Lisp_Object last_mouse_window;

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)
    {
      if (dpyinfo->mouse_face_hidden)
	goto set_cursor_shape;

      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;
      /* Record that some glyphs of this row are displayed in
         mouse-face.  */
      row->mouse_face_p = hl > 0;
      if (hl > 0)
	{
	  int vpos = row->y + WINDOW_TOP_EDGE_Y (w);
	  int kstart = start_hpos + WINDOW_LEFT_EDGE_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_LEFT_EDGE_X (w);
	  new_pos_Y = row->y + WINDOW_TOP_EDGE_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, lastcol, line_start_position, maybe_next_line_p = 0;
  int yb = window_text_bottom_y (w);
  struct glyph_row *row = MATRIX_ROW (w->current_matrix, 0), *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;

      /* Don't overstep the last matrix row, lest we get into the
	 never-never land... */
      if (row->y + 1 >= yb)
	break;

      ++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 fringes 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
	       /* in case someone implements scroll bars some day... */
	       - WINDOW_LEFT_SCROLL_BAR_AREA_WIDTH (w));
      end = glyph + row->used[TEXT_AREA];
      if (glyph < end
	  && STRINGP (glyph->object)
	  && STRING_INTERVALS (glyph->object)
	  && glyph->charpos >= 0
	  && glyph->charpos < SCHARS (glyph->object))
	{
	  /* 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 (!NILP (help))
	    {
	      help_echo_string = help;
	      XSETWINDOW (help_echo_window, w);
	      help_echo_object = glyph->object;
	      help_echo_pos = glyph->charpos;
	    }
	}
    }
}

/* Take proper action when the mouse has moved to position X, Y on
   frame F as regards highlighting characters that have mouse-face
   properties.  Also de-highlighting chars where the mouse was before.
   X and Y can be negative or out of range.  */
static void
IT_note_mouse_highlight (struct frame *f, int x, int y)
{
  struct display_info *dpyinfo = FRAME_X_DISPLAY_INFO (f);
  enum window_part part = ON_NOTHING;
  Lisp_Object window;
  struct window *w;

  /* When a menu is active, don't highlight because this looks odd.  */
  if (mouse_preempted)
    return;

  if (NILP (Vmouse_highlight)
      || !f->glyphs_initialized_p)
    return;

  dpyinfo->mouse_face_mouse_x = x;
  dpyinfo->mouse_face_mouse_y = y;
  dpyinfo->mouse_face_mouse_frame = f;

  if (dpyinfo->mouse_face_defer)
    return;

  if (gc_in_progress)
    {
      dpyinfo->mouse_face_deferred_gc = 1;
      return;
    }

  /* Which window is that in?  */
  window = window_from_coordinates (f, x, y, &part, &x, &y, 0);

  /* If we were displaying active text in another window, clear that.  */
  if (! EQ (window, dpyinfo->mouse_face_window))
    clear_mouse_face (dpyinfo);

  /* Not on a window -> return.  */
  if (!WINDOWP (window))
    return;

  /* Convert to window-relative coordinates.  */
  w = XWINDOW (window);

  if (part == ON_MODE_LINE || part == ON_HEADER_LINE)
    {
      /* Mouse is on the mode or top line.  */
      IT_note_mode_line_highlight (w, x, part == ON_MODE_LINE);
      return;
    }

  IT_set_mouse_pointer (0);

  /* Are we in a window whose display is up to date?
     And verify the buffer's text has not changed.  */
  if (part == ON_TEXT
      && EQ (w->window_end_valid, w->buffer)
      && XFASTINT (w->last_modified) == BUF_MODIFF (XBUFFER (w->buffer))
      && (XFASTINT (w->last_overlay_modified)
	  == BUF_OVERLAY_MODIFF (XBUFFER (w->buffer))))
    {
      int pos, i, nrows = w->current_matrix->nrows;
      struct glyph_row *row;
      struct glyph *glyph;

      /* Find the glyph under X/Y.  */
      glyph = NULL;
      if (y >= 0 && y < nrows)
	{
	  row = MATRIX_ROW (w->current_matrix, y);
	  /* Give up if some row before the one we are looking for is
	     not enabled.  */
	  for (i = 0; i <= y; i++)
	    if (!MATRIX_ROW (w->current_matrix, i)->enabled_p)
	      break;
	  if (i > y  /* all rows upto and including the one at Y are enabled */
	      && row->displays_text_p
	      && x <  window_box_width (w, TEXT_AREA))
	    {
	      glyph = row->glyphs[TEXT_AREA];
	      if (x >= row->used[TEXT_AREA])
		glyph = NULL;
	      else
		{
		  glyph += x;
		  if (!BUFFERP (glyph->object))
		    glyph = NULL;
		}
	    }
	}

      /* Clear mouse face if X/Y not over text.  */
      if (glyph == NULL)
	{
	  clear_mouse_face (dpyinfo);
	  return;
	}

      if (!BUFFERP (glyph->object))
	abort ();
      pos = glyph->charpos;

      /* Check for mouse-face and help-echo.  */
      {
	extern Lisp_Object Qmouse_face;
	Lisp_Object mouse_face, overlay, position, *overlay_vec;
	int len, noverlays, obegv, ozv;;
	struct buffer *obuf;

	/* If we get an out-of-range value, return now; avoid an error.  */
	if (pos > BUF_Z (XBUFFER (w->buffer)))
	  return;

	/* Make the window's buffer temporarily current for
	   overlays_at and compute_char_face.  */
	obuf = current_buffer;
	current_buffer = XBUFFER (w->buffer);
	obegv = BEGV;
	ozv = ZV;
	BEGV = BEG;
	ZV = Z;

	/* Is this char mouse-active or does it have help-echo?  */
	XSETINT (position, pos);

	/* Put all the overlays we want in a vector in overlay_vec.
	   Store the length in len.  If there are more than 10, make
	   enough space for all, and try again.  */
	len = 10;
	overlay_vec = (Lisp_Object *) alloca (len * sizeof (Lisp_Object));
	noverlays = overlays_at (pos, 0, &overlay_vec, &len, NULL, NULL, 0);
	if (noverlays > len)
	  {
	    len = noverlays;
	    overlay_vec = (Lisp_Object *) alloca (len * sizeof (Lisp_Object));
	    noverlays = overlays_at (pos,
				     0, &overlay_vec, &len, NULL, NULL, 0);
	  }

	/* Sort overlays into increasing priority order.  */
	noverlays = sort_overlays (overlay_vec, noverlays, w);

	/* Check mouse-face highlighting.  */
	if (! (EQ (window, dpyinfo->mouse_face_window)
	       && y >= dpyinfo->mouse_face_beg_row
	       && y <= dpyinfo->mouse_face_end_row
	       && (y > dpyinfo->mouse_face_beg_row
		   || x >= dpyinfo->mouse_face_beg_col)
	       && (y < dpyinfo->mouse_face_end_row
		   || x < dpyinfo->mouse_face_end_col
		   || dpyinfo->mouse_face_past_end)))
	  {
	    /* Clear the display of the old active region, if any.  */
	    clear_mouse_face (dpyinfo);

	    /* Find highest priority overlay that has a mouse-face prop.  */
	    overlay = Qnil;
	    for (i = noverlays - 1; i >= 0; --i)
	      {
		mouse_face = Foverlay_get (overlay_vec[i], Qmouse_face);
		if (!NILP (mouse_face))
		  {
		    overlay = overlay_vec[i];
		    break;
		  }
	      }

	    /* If no overlay applies, get a text property.  */
	    if (NILP (overlay))
	      mouse_face = Fget_text_property (position, Qmouse_face,
					       w->buffer);

	    /* Handle the overlay case.  */
	    if (! NILP (overlay))
	      {
		/* Find the range of text around this char that
		   should be active.  */
		Lisp_Object before, after;
		int ignore;

		before = Foverlay_start (overlay);
		after = Foverlay_end (overlay);
		/* Record this as the current active region.  */
		fast_find_position (w, XFASTINT (before),
				    &dpyinfo->mouse_face_beg_col,
				    &dpyinfo->mouse_face_beg_row);
		dpyinfo->mouse_face_past_end
		  = !fast_find_position (w, XFASTINT (after),
					 &dpyinfo->mouse_face_end_col,
					 &dpyinfo->mouse_face_end_row);
		dpyinfo->mouse_face_window = window;
		dpyinfo->mouse_face_face_id
		  = face_at_buffer_position (w, pos, 0, 0,
					     &ignore, pos + 1,
					     !dpyinfo->mouse_face_hidden);

		/* Display it as active.  */
		show_mouse_face (dpyinfo, 1);
	      }
	    /* Handle the text property case.  */
	    else if (! NILP (mouse_face))
	      {
		/* Find the range of text around this char that
		   should be active.  */
		Lisp_Object before, after, beginning, end;
		int ignore;

		beginning = Fmarker_position (w->start);
		XSETINT (end, (BUF_Z (XBUFFER (w->buffer))
			       - XFASTINT (w->window_end_pos)));
		before
		  = Fprevious_single_property_change (make_number (pos + 1),
						      Qmouse_face,
						      w->buffer, beginning);
		after
		  = Fnext_single_property_change (position, Qmouse_face,
						  w->buffer, end);
		/* Record this as the current active region.  */
		fast_find_position (w, XFASTINT (before),
				    &dpyinfo->mouse_face_beg_col,
				    &dpyinfo->mouse_face_beg_row);
		dpyinfo->mouse_face_past_end
		  = !fast_find_position (w, XFASTINT (after),
					 &dpyinfo->mouse_face_end_col,
					 &dpyinfo->mouse_face_end_row);
		dpyinfo->mouse_face_window = window;
		dpyinfo->mouse_face_face_id
		  = face_at_buffer_position (w, pos, 0, 0,
					     &ignore, pos + 1,
					     !dpyinfo->mouse_face_hidden);

		/* Display it as active.  */
		show_mouse_face (dpyinfo, 1);
	      }
	  }

	/* Look for a `help-echo' property.  */
	{
	  Lisp_Object help;
	  extern Lisp_Object Qhelp_echo;

	  /* Check overlays first.  */
	  help = Qnil;
	  for (i = noverlays - 1; i >= 0 && NILP (help); --i)
	    {
	      overlay = overlay_vec[i];
	      help = Foverlay_get (overlay, Qhelp_echo);
	    }

	  if (!NILP (help))
	    {
	      help_echo_string = help;
	      help_echo_window = window;
	      help_echo_object = overlay;
	      help_echo_pos = pos;
	    }
	  /* Try text properties.  */
	  else if (NILP (help)
		   && ((STRINGP (glyph->object)
			&& glyph->charpos >= 0
			&& glyph->charpos < SCHARS (glyph->object))
		       || (BUFFERP (glyph->object)
			   && glyph->charpos >= BEGV
			   && glyph->charpos < ZV)))
	    {
	      help = Fget_text_property (make_number (glyph->charpos),
					 Qhelp_echo, glyph->object);
	      if (!NILP (help))
		{
		  help_echo_string = help;
		  help_echo_window = window;
		  help_echo_object = glyph->object;
		  help_echo_pos = glyph->charpos;
		}
	    }
	}

	BEGV = obegv;
	ZV = ozv;
	current_buffer = obuf;
      }
    }
}

static void
IT_clear_end_of_line (int first_unused)
{
  char *spaces, *sp;
  int i, j, offset = 2 * (new_pos_X + screen_size_X * new_pos_Y);
  extern int fatal_error_in_progress;

  if (new_pos_X >= first_unused || fatal_error_in_progress)
    return;

  IT_set_face (0);
  i = (j = first_unused - new_pos_X) * 2;
  if (termscript)
    fprintf (termscript, "<CLR:EOL[%d..%d)>", new_pos_X, first_unused);
  spaces = sp = alloca (i);

  while (--j >= 0)
    {
      *sp++ = ' ';
      *sp++ = ScreenAttrib;
    }

  mouse_off_maybe ();
  dosmemput (spaces, i, (int)ScreenPrimary + offset);
  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (offset, i / 2);

  /* clear_end_of_line_raw on term.c leaves the cursor at first_unused.
     Let's follow their lead, in case someone relies on this.  */
  new_pos_X = first_unused;
}

static void
IT_clear_screen (void)
{
  if (termscript)
    fprintf (termscript, "<CLR:SCR>");
  /* We are sometimes called (from clear_garbaged_frames) when a new
     frame is being created, but its faces are not yet realized.  In
     such a case we cannot call IT_set_face, since it will fail to find
     any valid faces and will abort.  Instead, use the initial screen
     colors; that should mimic what a Unix tty does, which simply clears
     the screen with whatever default colors are in use.  */
  if (FACE_FROM_ID (SELECTED_FRAME (), DEFAULT_FACE_ID) == NULL)
    ScreenAttrib = (initial_screen_colors[0] << 4) | initial_screen_colors[1];
  else
    IT_set_face (0);
  mouse_off ();
  ScreenClear ();
  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (0, screen_size);
  new_pos_X = new_pos_Y = 0;
}

static void
IT_clear_to_end (void)
{
  if (termscript)
    fprintf (termscript, "<CLR:EOS>");

  while (new_pos_Y < screen_size_Y) {
    new_pos_X = 0;
    IT_clear_end_of_line (screen_size_X);
    new_pos_Y++;
  }
}

static void
IT_cursor_to (int y, int x)
{
  if (termscript)
    fprintf (termscript, "\n<XY=%dx%d>", x, y);
  new_pos_X = x;
  new_pos_Y = y;
}

static int cursor_cleared;

static void
IT_display_cursor (int on)
{
  if (on && cursor_cleared)
    {
      ScreenSetCursor (current_pos_Y, current_pos_X);
      cursor_cleared = 0;
    }
  else if (!on && !cursor_cleared)
    {
      ScreenSetCursor (-1, -1);
      cursor_cleared = 1;
    }
}

/* Emacs calls cursor-movement functions a lot when it updates the
   display (probably a legacy of old terminals where you cannot
   update a screen line without first moving the cursor there).
   However, cursor movement is expensive on MSDOS (it calls a slow
   BIOS function and requires 2 mode switches), while actual screen
   updates access the video memory directly and don't depend on
   cursor position.  To avoid slowing down the redisplay, we cheat:
   all functions that move the cursor only set internal variables
   which record the cursor position, whereas the cursor is only
   moved to its final position whenever screen update is complete.

   `IT_cmgoto' is called from the keyboard reading loop and when the
   frame update is complete.  This means that we are ready for user
   input, so we update the cursor position to show where the point is,
   and also make the mouse pointer visible.

   Special treatment is required when the cursor is in the echo area,
   to put the cursor at the end of the text displayed there.  */

static void
IT_cmgoto (FRAME_PTR f)
{
  /* Only set the cursor to where it should be if the display is
     already in sync with the window contents.  */
  int update_cursor_pos = 1; /* MODIFF == unchanged_modified; */

  /* FIXME: This needs to be rewritten for the new redisplay, or
     removed.  */
#if 0
  static int previous_pos_X = -1;

  update_cursor_pos = 1;	/* temporary!!! */

  /* If the display is in sync, forget any previous knowledge about
     cursor position.  This is primarily for unexpected events like
     C-g in the minibuffer.  */
  if (update_cursor_pos && previous_pos_X >= 0)
    previous_pos_X = -1;
  /* If we are in the echo area, put the cursor at the
     end of the echo area message.  */
  if (!update_cursor_pos
      && WINDOW_TOP_EDGE_LINE (XWINDOW (FRAME_MINIBUF_WINDOW (f))) <= new_pos_Y)
    {
      int tem_X = current_pos_X, dummy;

      if (echo_area_glyphs)
	{
	  tem_X = echo_area_glyphs_length;
	  /* Save current cursor position, to be restored after the
	     echo area message is erased.  Only remember one level
	     of previous cursor position.  */
	  if (previous_pos_X == -1)
	    ScreenGetCursor (&dummy, &previous_pos_X);
	}
      else if (previous_pos_X >= 0)
	{
	  /* We wind up here after the echo area message is erased.
	     Restore the cursor position we remembered above.  */
	  tem_X = previous_pos_X;
	  previous_pos_X = -1;
	}

      if (current_pos_X != tem_X)
	{
	  new_pos_X = tem_X;
	  update_cursor_pos = 1;
	}
    }
#endif

  if (update_cursor_pos
      && (current_pos_X != new_pos_X || current_pos_Y != new_pos_Y))
    {
      ScreenSetCursor (current_pos_Y = new_pos_Y, current_pos_X = new_pos_X);
      if (termscript)
	fprintf (termscript, "\n<CURSOR:%dx%d>", current_pos_X, current_pos_Y);
    }

  /* Maybe cursor is invisible, so make it visible.  */
  IT_display_cursor (1);

  /* Mouse pointer should be always visible if we are waiting for
     keyboard input.  */
  if (!mouse_visible)
    mouse_on ();
}

static void
IT_update_begin (struct frame *f)
{
  struct display_info *display_info = FRAME_X_DISPLAY_INFO (f);
  struct frame *mouse_face_frame = display_info->mouse_face_mouse_frame;

  BLOCK_INPUT;

  if (f && f == mouse_face_frame)
    {
      /* Don't do highlighting for mouse motion during the update.  */
      display_info->mouse_face_defer = 1;

      /* If F needs to be redrawn, simply forget about any prior mouse
	 highlighting.  */
      if (FRAME_GARBAGED_P (f))
	display_info->mouse_face_window = Qnil;

      /* Can we tell that this update does not affect the window
	 where the mouse highlight is?  If so, no need to turn off.
	 Likewise, don't do anything if none of the enabled rows
	 contains glyphs highlighted in mouse face.  */
      if (!NILP (display_info->mouse_face_window)
	  && WINDOWP (display_info->mouse_face_window))
	{
	  struct window *w = XWINDOW (display_info->mouse_face_window);
	  int i;

	  /* If the mouse highlight is in the window that was deleted
	     (e.g., if it was popped by completion), clear highlight
	     unconditionally.  */
	  if (NILP (w->buffer))
	    display_info->mouse_face_window = Qnil;
	  else
	    {
	      for (i = 0; i < w->desired_matrix->nrows; ++i)
		if (MATRIX_ROW_ENABLED_P (w->desired_matrix, i)
		    && MATRIX_ROW (w->current_matrix, i)->mouse_face_p)
		  break;
	    }

	  if (NILP (w->buffer) || i < w->desired_matrix->nrows)
	    clear_mouse_face (display_info);
	}
    }
  else if (mouse_face_frame && !FRAME_LIVE_P (mouse_face_frame))
    {
      /* If the frame with mouse highlight was deleted, invalidate the
	 highlight info.  */
      display_info->mouse_face_beg_row = display_info->mouse_face_beg_col = -1;
      display_info->mouse_face_end_row = display_info->mouse_face_end_col = -1;
      display_info->mouse_face_window = Qnil;
      display_info->mouse_face_deferred_gc = 0;
      display_info->mouse_face_mouse_frame = NULL;
    }

  UNBLOCK_INPUT;
}

static void
IT_update_end (struct frame *f)
{
  FRAME_X_DISPLAY_INFO (f)->mouse_face_defer = 0;
}

static void
IT_frame_up_to_date (struct frame *f)
{
  struct display_info *dpyinfo = FRAME_X_DISPLAY_INFO (f);
  Lisp_Object new_cursor, frame_desired_cursor;
  struct window *sw;

  if (dpyinfo->mouse_face_deferred_gc
      || (f && f == dpyinfo->mouse_face_mouse_frame))
    {
      BLOCK_INPUT;
      if (dpyinfo->mouse_face_mouse_frame)
	IT_note_mouse_highlight (dpyinfo->mouse_face_mouse_frame,
				 dpyinfo->mouse_face_mouse_x,
				 dpyinfo->mouse_face_mouse_y);
      dpyinfo->mouse_face_deferred_gc = 0;
      UNBLOCK_INPUT;
    }

  /* Set the cursor type to whatever they wanted.  In a minibuffer
     window, we want the cursor to appear only if we are reading input
     from this window, and we want the cursor to be taken from the
     frame parameters.  For the selected window, we use either its
     buffer-local value or the value from the frame parameters if the
     buffer doesn't define its local value for the cursor type.  */
  sw = XWINDOW (f->selected_window);
  frame_desired_cursor = Fcdr (Fassq (Qcursor_type, f->param_alist));
  if (cursor_in_echo_area
      && FRAME_HAS_MINIBUF_P (f)
      && EQ (FRAME_MINIBUF_WINDOW (f), echo_area_window)
      && sw == XWINDOW (echo_area_window))
    new_cursor = frame_desired_cursor;
  else
    {
      struct buffer *b = XBUFFER (sw->buffer);

      if (EQ (b->cursor_type, Qt))
	new_cursor = frame_desired_cursor;
      else if (NILP (b->cursor_type)) /* nil means no cursor */
	new_cursor = Fcons (Qbar, make_number (0));
      else
	new_cursor = b->cursor_type;
    }

  IT_set_cursor_type (f, new_cursor);

  IT_cmgoto (f);  /* position cursor when update is done */
}

/* Copy LEN glyphs displayed on a single line whose vertical position
   is YPOS, beginning at horizontal position XFROM to horizontal
   position XTO, by moving blocks in the video memory.  Used by
   functions that insert and delete glyphs.  */
static void
IT_copy_glyphs (int xfrom, int xto, size_t len, int ypos)
{
  /* The offsets of source and destination relative to the
     conventional memorty selector.  */
  int from = 2 * (xfrom + screen_size_X * ypos) + ScreenPrimary;
  int to = 2 * (xto + screen_size_X * ypos) + ScreenPrimary;

  if (from == to || len <= 0)
    return;

  _farsetsel (_dos_ds);

  /* The source and destination might overlap, so we need to move
     glyphs non-destructively.  */
  if (from > to)
    {
      for ( ; len; from += 2, to += 2, len--)
	_farnspokew (to, _farnspeekw (from));
    }
  else
    {
      from += (len - 1) * 2;
      to += (len - 1) * 2;
      for ( ; len; from -= 2, to -= 2, len--)
	_farnspokew (to, _farnspeekw (from));
    }
  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (ypos * screen_size_X * 2, screen_size_X);
}

/* Insert and delete glyphs.  */
static void
IT_insert_glyphs (start, len)
     register struct glyph *start;
     register int len;
{
  int shift_by_width = screen_size_X - (new_pos_X + len);

  /* Shift right the glyphs from the nominal cursor position to the
     end of this line.  */
  IT_copy_glyphs (new_pos_X, new_pos_X + len, shift_by_width, new_pos_Y);

  /* Now write the glyphs to be inserted.  */
  IT_write_glyphs (start, len);
}

static void
IT_delete_glyphs (n)
     register int n;
{
  abort ();
}

/* set-window-configuration on window.c needs this.  */
void
x_set_menu_bar_lines (f, value, oldval)
     struct frame *f;
     Lisp_Object value, oldval;
{
  set_menu_bar_lines (f, value, oldval);
}

/* This was copied from xfaces.c  */

extern Lisp_Object Qbackground_color;
extern Lisp_Object Qforeground_color;
Lisp_Object Qreverse;
extern Lisp_Object Qtitle;

/* IT_set_terminal_modes is called when emacs is started,
   resumed, and whenever the screen is redrawn!  */

static void
IT_set_terminal_modes (void)
{
  if (termscript)
    fprintf (termscript, "\n<SET_TERM>");

  screen_size_X = ScreenCols ();
  screen_size_Y = ScreenRows ();
  screen_size = screen_size_X * screen_size_Y;

  new_pos_X = new_pos_Y = 0;
  current_pos_X = current_pos_Y = -1;

  if (term_setup_done)
    return;
  term_setup_done = 1;

  startup_screen_size_X = screen_size_X;
  startup_screen_size_Y = screen_size_Y;
  startup_screen_attrib = ScreenAttrib;

#if __DJGPP__ > 1
  /* Is DOS/V (or any other RSIS software which relocates
     the screen) installed?  */
  {
    unsigned short es_value;
    __dpmi_regs regs;

    regs.h.ah = 0xfe;	/* get relocated screen address */
    if (ScreenPrimary == 0xb0000UL || ScreenPrimary == 0xb8000UL)
      regs.x.es = (ScreenPrimary >> 4) & 0xffff;
    else if (screen_old_address) /* already switched to Japanese mode once */
      regs.x.es = (screen_old_address >> 4) & 0xffff;
    else
      regs.x.es = ScreenMode () == 7 ? 0xb000 : 0xb800;
    regs.x.di = 0;
    es_value = regs.x.es;
    __dpmi_int (0x10, &regs);

    if (regs.x.es != es_value)
      {
	/* screen_old_address is only set if ScreenPrimary does NOT
	   already point to the relocated buffer address returned by
	   the Int 10h/AX=FEh call above.  DJGPP v2.02 and later sets
	   ScreenPrimary to that address at startup under DOS/V.  */
	if (regs.x.es != (ScreenPrimary >> 4) & 0xffff)
	  screen_old_address = ScreenPrimary;
	screen_virtual_segment = regs.x.es;
	screen_virtual_offset  = regs.x.di;
	ScreenPrimary = (screen_virtual_segment << 4) + screen_virtual_offset;
      }
  }
#endif /* __DJGPP__ > 1 */

  ScreenGetCursor (&startup_pos_Y, &startup_pos_X);
  ScreenRetrieve (startup_screen_buffer = xmalloc (screen_size * 2));

  if (termscript)
    fprintf (termscript, "<SCREEN SAVED (dimensions=%dx%d)>\n",
	     screen_size_X, screen_size_Y);

  bright_bg ();
}

/* IT_reset_terminal_modes is called when emacs is
   suspended or killed.  */

static void
IT_reset_terminal_modes (void)
{
  int display_row_start = (int) ScreenPrimary;
  int saved_row_len     = startup_screen_size_X * 2;
  int update_row_len    = ScreenCols () * 2, current_rows = ScreenRows ();
  int to_next_row       = update_row_len;
  unsigned char *saved_row = startup_screen_buffer;
  int cursor_pos_X = ScreenCols () - 1, cursor_pos_Y = ScreenRows () - 1;

  if (termscript)
    fprintf (termscript, "\n<RESET_TERM>");

  if (!term_setup_done)
    return;

  mouse_off ();

  /* Leave the video system in the same state as we found it,
     as far as the blink/bright-background bit is concerned.  */
  maybe_enable_blinking ();

  /* We have a situation here.
     We cannot just do ScreenUpdate(startup_screen_buffer) because
     the luser could have changed screen dimensions inside Emacs
     and failed (or didn't want) to restore them before killing
     Emacs.  ScreenUpdate() uses the *current* screen dimensions and
     thus will happily use memory outside what was allocated for
     `startup_screen_buffer'.
     Thus we only restore as much as the current screen dimensions
     can hold, and clear the rest (if the saved screen is smaller than
     the current) with the color attribute saved at startup.  The cursor
     is also restored within the visible dimensions.  */

  ScreenAttrib = startup_screen_attrib;

  /* Don't restore the screen if we are exiting less than 2 seconds
     after startup: we might be crashing, and the screen might show
     some vital clues to what's wrong.  */
  if (clock () - startup_time >= 2*CLOCKS_PER_SEC)
    {
      ScreenClear ();
      if (screen_virtual_segment)
	dosv_refresh_virtual_screen (0, screen_size);

      if (update_row_len > saved_row_len)
	update_row_len = saved_row_len;
      if (current_rows > startup_screen_size_Y)
	current_rows = startup_screen_size_Y;

      if (termscript)
	fprintf (termscript, "<SCREEN RESTORED (dimensions=%dx%d)>\n",
		 update_row_len / 2, current_rows);

      while (current_rows--)
	{
	  dosmemput (saved_row, update_row_len, display_row_start);
	  if (screen_virtual_segment)
	    dosv_refresh_virtual_screen (display_row_start - ScreenPrimary,
					 update_row_len / 2);
	  saved_row         += saved_row_len;
	  display_row_start += to_next_row;
	}
    }
  if (startup_pos_X < cursor_pos_X)
    cursor_pos_X = startup_pos_X;
  if (startup_pos_Y < cursor_pos_Y)
    cursor_pos_Y = startup_pos_Y;

  ScreenSetCursor (cursor_pos_Y, cursor_pos_X);
  xfree (startup_screen_buffer);

  term_setup_done = 0;
}

static void
IT_set_terminal_window (int foo)
{
}

/* Remember the screen colors of the curent frame, to serve as the
   default colors for newly-created frames.  */
DEFUN ("msdos-remember-default-colors", Fmsdos_remember_default_colors,
       Smsdos_remember_default_colors, 1, 1, 0,
       doc: /* Remember the screen colors of the current frame.  */)
     (frame)
     Lisp_Object frame;
{
  struct frame *f;

  CHECK_FRAME (frame);
  f= XFRAME (frame);

  /* This function is called after applying default-frame-alist to the
     initial frame.  At that time, if reverse-colors option was
     specified in default-frame-alist, it was already applied, and
     frame colors are reversed.  We need to account for that.  */
  if (EQ (Fcdr (Fassq (Qreverse, f->param_alist)), Qt))
    {
      initial_screen_colors[0] = FRAME_BACKGROUND_PIXEL (f);
      initial_screen_colors[1] = FRAME_FOREGROUND_PIXEL (f);
    }
  else
    {
      initial_screen_colors[0] = FRAME_FOREGROUND_PIXEL (f);
      initial_screen_colors[1] = FRAME_BACKGROUND_PIXEL (f);
    }
}

void
IT_set_frame_parameters (f, alist)
     struct frame *f;
     Lisp_Object alist;
{
  Lisp_Object tail;
  int i, j, length = XINT (Flength (alist));
  Lisp_Object *parms
    = (Lisp_Object *) alloca (length * sizeof (Lisp_Object));
  Lisp_Object *values
    = (Lisp_Object *) alloca (length * sizeof (Lisp_Object));
  /* Do we have to reverse the foreground and background colors?  */
  int reverse = EQ (Fcdr (Fassq (Qreverse, f->param_alist)), Qt);
  int need_to_reverse, was_reverse = reverse;
  int redraw = 0, fg_set = 0, bg_set = 0;
  unsigned long orig_fg, orig_bg;
  Lisp_Object frame_bg, frame_fg;
  extern Lisp_Object Qdefault, QCforeground, QCbackground;

  /* If we are creating a new frame, begin with the original screen colors
     used for the initial frame.  */
  if (alist == Vdefault_frame_alist
      && initial_screen_colors[0] != -1 && initial_screen_colors[1] != -1)
    {
      FRAME_FOREGROUND_PIXEL (f) = initial_screen_colors[0];
      FRAME_BACKGROUND_PIXEL (f) = initial_screen_colors[1];
    }
  orig_fg = FRAME_FOREGROUND_PIXEL (f);
  orig_bg = FRAME_BACKGROUND_PIXEL (f);
  frame_fg = Fcdr (Fassq (Qforeground_color, f->param_alist));
  frame_bg = Fcdr (Fassq (Qbackground_color, f->param_alist));
  /* frame_fg and frame_bg could be nil if, for example,
     f->param_alist is nil, e.g. if we are called from
     Fmake_terminal_frame.  */
  if (NILP (frame_fg))
    frame_fg = build_string (unspecified_fg);
  if (NILP (frame_bg))
    frame_bg = build_string (unspecified_bg);

  /* Extract parm names and values into those vectors.  */
  i = 0;
  for (tail = alist; CONSP (tail); tail = Fcdr (tail))
    {
      Lisp_Object elt;

      elt = Fcar (tail);
      parms[i] = Fcar (elt);
      CHECK_SYMBOL (parms[i]);
      values[i] = Fcdr (elt);
      i++;
    }

  j = i;

  for (i = 0; i < j; i++)
    {
      Lisp_Object prop, val;

      prop = parms[i];
      val  = values[i];

      if (EQ (prop, Qreverse))
	reverse = EQ (val, Qt);
    }

  need_to_reverse = reverse && !was_reverse;
  if (termscript && need_to_reverse)
    fprintf (termscript, "<INVERSE-VIDEO>\n");

  /* Now process the alist elements in reverse of specified order.  */
  for (i--; i >= 0; i--)
    {
      Lisp_Object prop, val, frame;

      prop = parms[i];
      val  = values[i];

      if (EQ (prop, Qforeground_color))
	{
	  unsigned long new_color = load_color (f, NULL, val, need_to_reverse
						? LFACE_BACKGROUND_INDEX
						: LFACE_FOREGROUND_INDEX);
	  if (new_color !=  FACE_TTY_DEFAULT_COLOR
	      && new_color != FACE_TTY_DEFAULT_FG_COLOR
	      && new_color != FACE_TTY_DEFAULT_BG_COLOR)
	    {
	      FRAME_FOREGROUND_PIXEL (f) = new_color;
	      /* Make sure the foreground of the default face for this
		 frame is changed as well.  */
	      XSETFRAME (frame, f);
	      if (need_to_reverse)
		{
		  Finternal_set_lisp_face_attribute (Qdefault, QCbackground,
						     val, frame);
		  prop = Qbackground_color;
		  bg_set = 1;
		}
	      else
		{
		  Finternal_set_lisp_face_attribute (Qdefault, QCforeground,
						     val, frame);
		  fg_set = 1;
		}
	      redraw = 1;
	      if (termscript)
		fprintf (termscript, "<FGCOLOR %lu>\n", new_color);
	    }
	}
      else if (EQ (prop, Qbackground_color))
	{
	  unsigned long new_color = load_color (f, NULL, val, need_to_reverse
						? LFACE_FOREGROUND_INDEX
						: LFACE_BACKGROUND_INDEX);
	  if (new_color != FACE_TTY_DEFAULT_COLOR
	      && new_color != FACE_TTY_DEFAULT_FG_COLOR
	      && new_color != FACE_TTY_DEFAULT_BG_COLOR)
	    {
	      FRAME_BACKGROUND_PIXEL (f) = new_color;
	      /* Make sure the background of the default face for this
		 frame is changed as well.  */
	      XSETFRAME (frame, f);
	      if (need_to_reverse)
		{
		  Finternal_set_lisp_face_attribute (Qdefault, QCforeground,
						     val, frame);
		  prop = Qforeground_color;
		  fg_set = 1;
		}
	      else
		{
		  Finternal_set_lisp_face_attribute (Qdefault, QCbackground,
						     val, frame);
		  bg_set = 1;
		}
	      redraw = 1;
	      if (termscript)
		fprintf (termscript, "<BGCOLOR %lu>\n", new_color);
	    }
	}
      else if (EQ (prop, Qtitle))
	{
	  x_set_title (f, val);
	  if (termscript)
	    fprintf (termscript, "<TITLE: %s>\n", SDATA (val));
	}
      else if (EQ (prop, Qcursor_type))
	{
	  IT_set_cursor_type (f, val);
	  if (termscript)
	    fprintf (termscript, "<CTYPE: %s>\n",
		     EQ (val, Qbar) || EQ (val, Qhbar)
		     || CONSP (val) && (EQ (XCAR (val), Qbar)
					|| EQ (XCAR (val), Qhbar))
		     ? "bar" : "box");
	}
      store_frame_param (f, prop, val);
    }

  /* If they specified "reverse", but not the colors, we need to swap
     the current frame colors.  */
  if (need_to_reverse)
    {
      Lisp_Object frame;

      if (!fg_set)
	{
	  XSETFRAME (frame, f);
	  Finternal_set_lisp_face_attribute (Qdefault, QCforeground,
					     tty_color_name (f, orig_bg),
					     frame);
	  redraw = 1;
	}
      if (!bg_set)
	{
	  XSETFRAME (frame, f);
	  Finternal_set_lisp_face_attribute (Qdefault, QCbackground,
					     tty_color_name (f, orig_fg),
					     frame);
	  redraw = 1;
	}
    }

  if (redraw)
    {
      face_change_count++;	/* forces xdisp.c to recompute basic faces */
      if (f == SELECTED_FRAME())
	redraw_frame (f);
    }
}

extern void init_frame_faces (FRAME_PTR);

#endif /* !HAVE_X_WINDOWS */


/* Do we need the internal terminal?  */

void
internal_terminal_init ()
{
  char *term = getenv ("TERM"), *colors;
  struct frame *sf = SELECTED_FRAME();

#ifdef HAVE_X_WINDOWS
  if (!inhibit_window_system)
    return;
#endif

  internal_terminal
    = (!noninteractive) && term && !strcmp (term, "internal");

  if (getenv ("EMACSTEST"))
    termscript = fopen (getenv ("EMACSTEST"), "wt");

#ifndef HAVE_X_WINDOWS
  if (!internal_terminal || inhibit_window_system)
    {
      sf->output_method = output_termcap;
      return;
    }

  Vwindow_system = intern ("pc");
  Vwindow_system_version = make_number (1);
  sf->output_method = output_msdos_raw;

  /* If Emacs was dumped on DOS/V machine, forget the stale VRAM address.  */
  screen_old_address = 0;

  /* Forget the stale screen colors as well.  */
  initial_screen_colors[0] = initial_screen_colors[1] = -1;

  bzero (&the_only_x_display, sizeof the_only_x_display);
  the_only_x_display.background_pixel = 7; /* White */
  the_only_x_display.foreground_pixel = 0; /* Black */
  bright_bg ();
  colors = getenv ("EMACSCOLORS");
  if (colors && strlen (colors) >= 2)
    {
      /* The colors use 4 bits each (we enable bright background).  */
      if (isdigit (colors[0]))
        colors[0] -= '0';
      else if (isxdigit (colors[0]))
        colors[0] -= (isupper (colors[0]) ? 'A' : 'a') - 10;
      if (colors[0] >= 0 && colors[0] < 16)
        the_only_x_display.foreground_pixel = colors[0];
      if (isdigit (colors[1]))
        colors[1] -= '0';
      else if (isxdigit (colors[1]))
        colors[1] -= (isupper (colors[1]) ? 'A' : 'a') - 10;
      if (colors[1] >= 0 && colors[1] < 16)
        the_only_x_display.background_pixel = colors[1];
    }
  the_only_x_display.font = (XFontStruct *)1;   /* must *not* be zero */
  the_only_x_display.display_info.mouse_face_mouse_frame = NULL;
  the_only_x_display.display_info.mouse_face_deferred_gc = 0;
  the_only_x_display.display_info.mouse_face_beg_row =
    the_only_x_display.display_info.mouse_face_beg_col = -1;
  the_only_x_display.display_info.mouse_face_end_row =
    the_only_x_display.display_info.mouse_face_end_col = -1;
  the_only_x_display.display_info.mouse_face_face_id = DEFAULT_FACE_ID;
  the_only_x_display.display_info.mouse_face_window = Qnil;
  the_only_x_display.display_info.mouse_face_mouse_x =
    the_only_x_display.display_info.mouse_face_mouse_y = 0;
  the_only_x_display.display_info.mouse_face_defer = 0;
  the_only_x_display.display_info.mouse_face_hidden = 0;

  init_frame_faces (sf);

  ring_bell_hook = IT_ring_bell;
  insert_glyphs_hook = IT_insert_glyphs;
  delete_glyphs_hook = IT_delete_glyphs;
  write_glyphs_hook = IT_write_glyphs;
  cursor_to_hook = raw_cursor_to_hook = IT_cursor_to;
  clear_to_end_hook = IT_clear_to_end;
  clear_end_of_line_hook = IT_clear_end_of_line;
  clear_frame_hook = IT_clear_screen;
  update_begin_hook = IT_update_begin;
  update_end_hook = IT_update_end;
  frame_up_to_date_hook = IT_frame_up_to_date;

  /* These hooks are called by term.c without being checked.  */
  set_terminal_modes_hook = IT_set_terminal_modes;
  reset_terminal_modes_hook = IT_reset_terminal_modes;
  set_terminal_window_hook = IT_set_terminal_window;
  char_ins_del_ok = 0;
#endif
}

dos_get_saved_screen (screen, rows, cols)
     char **screen;
     int *rows;
     int *cols;
{
#ifndef HAVE_X_WINDOWS
  *screen = startup_screen_buffer;
  *cols = startup_screen_size_X;
  *rows = startup_screen_size_Y;
  return *screen != (char *)0;
#else
  return 0;
#endif
}

#ifndef HAVE_X_WINDOWS

/* We are not X, but we can emulate it well enough for our needs... */
void
check_x (void)
{
  if (! FRAME_MSDOS_P (SELECTED_FRAME()))
    error ("Not running under a window system");
}

#endif

\f
/* ----------------------- Keyboard control ----------------------
 *
 * Keymaps reflect the following keyboard layout:
 *
 *    0  1  2  3  4  5  6  7  8  9  10 11 12  BS
 *    TAB 15 16 17 18 19 20 21 22 23 24 25 26 (41)
 *    CLOK 30 31 32 33 34 35 36 37 38 39 40 (41) RET
 *    SH () 45 46 47 48 49 50 51 52 53 54  SHIFT
 *                    SPACE
 */

#define Ignore	0x0000
#define Normal	0x0000	/* normal key - alt changes scan-code */
#define FctKey	0x1000	/* func key if c == 0, else c */
#define Special	0x2000	/* func key even if c != 0 */
#define ModFct	0x3000	/* special if mod-keys, else 'c' */
#define Map	0x4000	/* alt scan-code, map to unshift/shift key */
#define KeyPad	0x5000	/* map to insert/kp-0 depending on c == 0xe0 */
#define Grey	0x6000	/* Grey keypad key */

#define Alt	0x0100	/* alt scan-code */
#define Ctrl	0x0200	/* ctrl scan-code */
#define Shift	0x0400	/* shift scan-code */

static int extended_kbd; /* 101 (102) keyboard present.	*/

struct kbd_translate {
  unsigned char  sc;
  unsigned char  ch;
  unsigned short code;
};

struct dos_keyboard_map
{
  char *unshifted;
  char *shifted;
  char *alt_gr;
  struct kbd_translate *translate_table;
};


static struct dos_keyboard_map us_keyboard = {
/* 0         1         2         3         4         5      */
/* 01234567890123456789012345678901234567890 12345678901234 */
  "`1234567890-=  qwertyuiop[]   asdfghjkl;'\\   zxcvbnm,./  ",
/* 0123456789012345678901234567890123456789 012345678901234 */
  "~!@#$%^&*()_+  QWERTYUIOP{}   ASDFGHJKL:\"|   ZXCVBNM<>?  ",
  0,				/* no Alt-Gr key */
  0				/* no translate table */
};

static struct dos_keyboard_map fr_keyboard = {
/* 0         1         2         3         4         5      */
/* 012 3456789012345678901234567890123456789012345678901234 */