src/msdos.c

/* MS-DOS specific C utilities.
   Copyright (C) 1993, 1994, 1995, 1996 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 <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. */
#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 "dosfns.h"
#include "msdos.h"
#include "systime.h"
#include "termhooks.h"
#include "dispextern.h"
#include "termopts.h"
#include "frame.h"
#include "window.h"
#include "buffer.h"
#include "commands.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.
 */

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;
    }
}

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 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_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;
  union REGS regs;

  regs.x.ax = 0x0003;
  int86 (0x33, &regs, &regs);
  *f = selected_frame;
  *bar_window = Qnil;
  mouse_get_xy (&ix, &iy);
  selected_frame->mouse_moved = 0;
  *x = make_number (ix);
  *y = make_number (iy);
  *time = event_timestamp ();
}

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;
}

void
mouse_init ()
{
  union REGS regs;

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

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

  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 highlight;

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 int term_setup_done;

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

/* This is never dereferenced.  */
Display *x_current_display;

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

#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);
#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
visible_bell_0:
	movl   _ScreenPrimary,%%eax
	call   dosmemsetup
	movl   %%eax,%%ebx
	movl   %1,%%ecx
	movb   %0,%%al
	incl   %%ebx
visible_bell_1:
	xorb   %%al,%%gs:(%%ebx)
	addl   $2,%%ebx
	decl   %%ecx
	jne    visible_bell_1
	decb   %%dl
	jne    visible_bell_3
visible_bell_2:
	movzwl %%ax,%%eax
        movzwl %%ax,%%eax
	movzwl %%ax,%%eax
	movzwl %%ax,%%eax
	decw   %%cx
	jne    visible_bell_2
	jmp    visible_bell_0
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);
    }
}

/* 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];
  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;

  /* Do we have a VGA?  */
  regs.x.ax = 0x1a00;
  int86 (0x10, &regs, &regs);
  if (regs.h.al == 0x1a && regs.h.bl > 5 && regs.h.bl < 13)
    have_vga = 1;

  mouse_off ();

  /* 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;
	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)
	       _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 ();

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

/* 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 ();
}

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

static void
IT_set_face (int face)
{
  struct face *fp;
  extern struct face *intern_face (/* FRAME_PTR, struct face * */);

  if (face == 1 || (face == 0 && highlight))
    fp = FRAME_MODE_LINE_FACE (foo);
  else if (face <= 0 || face >= FRAME_N_COMPUTED_FACES (foo))
    fp = FRAME_DEFAULT_FACE (foo);
  else
    fp = intern_face (selected_frame, FRAME_COMPUTED_FACES (foo)[face]);
  if (termscript)
    fprintf (termscript, "<FACE:%d:%d>", FACE_FOREGROUND (fp), FACE_BACKGROUND (fp));
  screen_face = face;
  ScreenAttrib = (FACE_BACKGROUND (fp) << 4) | FACE_FOREGROUND (fp);
}

static
IT_write_glyphs (GLYPH *str, int len)
{
  int newface;
  int ch, l = len;
  unsigned char *buf, *bp;

  if (len == 0) return;

  buf = bp = alloca (len * 2);

  while (--l >= 0)
    {
      newface = FAST_GLYPH_FACE (*str);
      if (newface != screen_face)
	IT_set_face (newface);
      ch = FAST_GLYPH_CHAR (*str);
      *bp++ = (unsigned char)ch;
      *bp++ = ScreenAttrib;

      if (termscript)
	fputc (ch, termscript);
      str++;
    }

  mouse_off_maybe ();
  dosmemput (buf, 2 * len,
	     (int)ScreenPrimary + 2 * (new_pos_X + screen_size_X * new_pos_Y));
  new_pos_X += len;
}

static
IT_clear_end_of_line (first_unused)
{
  char *spaces, *sp;
  int i, j;

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

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

  mouse_off_maybe ();
  dosmemput (spaces, i,
	     (int)ScreenPrimary + 2 * (new_pos_X + screen_size_X * new_pos_Y));
}

static
IT_clear_screen (void)
{
  if (termscript)
    fprintf (termscript, "<CLR:SCR>");
  IT_set_face (0);
  mouse_off ();
  ScreenClear ();
  new_pos_X = new_pos_Y = 0;
}

static
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 (0);
    new_pos_Y++;
  }
}

static
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
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
IT_cmgoto (f)
     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 = MODIFF == unchanged_modified;

  /* If we are in the echo area, put the cursor at the end of text.  */
  if (!update_cursor_pos
      && XFASTINT (XWINDOW (FRAME_MINIBUF_WINDOW (f))->top) <= new_pos_Y)
    {
      new_pos_X = FRAME_DESIRED_GLYPHS (f)->used[new_pos_Y];
      update_cursor_pos = 1;
    }

  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
IT_reassert_line_highlight (new, vpos)
     int new, vpos;
{
  highlight = new;
  IT_set_face (0); /* To possibly clear the highlighting.  */
}

static
IT_change_line_highlight (new_highlight, vpos, first_unused_hpos)
{
  highlight = new_highlight;
  IT_set_face (0); /* To possibly clear the highlighting.  */
  IT_cursor_to (vpos, 0);
  IT_clear_end_of_line (first_unused_hpos);
}

static
IT_update_begin ()
{
  highlight = 0;
  IT_set_face (0); /* To possibly clear the highlighting.  */
  screen_face = -1;
}

static
IT_update_end ()
{
}

/* This was more or less copied from xterm.c

   Nowadays, the corresponding function under X is `x_set_menu_bar_lines_1'
   on xfns.c  */

static void
IT_set_menu_bar_lines (window, n)
     Lisp_Object window;
     int n;
{
  struct window *w = XWINDOW (window);

  XSETFASTINT (w->last_modified, 0);
  XSETFASTINT (w->last_overlay_modified, 0);
  XSETFASTINT (w->top, XFASTINT (w->top) + n);
  XSETFASTINT (w->height, XFASTINT (w->height) - n);

  /* Handle just the top child in a vertical split.  */
  if (!NILP (w->vchild))
    IT_set_menu_bar_lines (w->vchild, n);

  /* Adjust all children in a horizontal split.  */
  for (window = w->hchild; !NILP (window); window = w->next)
    {
      w = XWINDOW (window);
      IT_set_menu_bar_lines (window, n);
    }
}

/* This was copied from xfns.c  */

Lisp_Object Qbackground_color;
Lisp_Object Qforeground_color;

void
x_set_menu_bar_lines (f, value, oldval)
     struct frame *f;
     Lisp_Object value, oldval;
{
  int nlines;
  int olines = FRAME_MENU_BAR_LINES (f);

  /* Right now, menu bars don't work properly in minibuf-only frames;
     most of the commands try to apply themselves to the minibuffer
     frame itslef, and get an error because you can't switch buffers
     in or split the minibuffer window.  */
  if (FRAME_MINIBUF_ONLY_P (f))
    return;

  if (INTEGERP (value))
    nlines = XINT (value);
  else
    nlines = 0;

  FRAME_MENU_BAR_LINES (f) = nlines;
  IT_set_menu_bar_lines (f->root_window, nlines - olines);
}

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

static
IT_set_terminal_modes (void)
{
  if (termscript)
    fprintf (termscript, "\n<SET_TERM>");
  highlight = 0;

  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;

  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
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;
  int current_rows      = ScreenRows ();
  int to_next_row       = update_row_len;
  unsigned char *saved_row = startup_screen_buffer;
  int cursor_pos_X = ScreenCols () - 1;
  int cursor_pos_Y = ScreenRows () - 1;

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

  highlight = 0;

  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;
  ScreenClear ();

  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);
      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
IT_set_terminal_window (void)
{
}

void
IT_set_frame_parameters (f, alist)
     FRAME_PTR f;
     Lisp_Object alist;
{
  Lisp_Object tail;
  int redraw;
  extern unsigned long load_color ();

  redraw = 0;
  for (tail = alist; CONSP (tail); tail = Fcdr (tail))
    {
      Lisp_Object elt, prop, val;

      elt = Fcar (tail);
      prop = Fcar (elt);
      val = Fcdr (elt);
      CHECK_SYMBOL (prop, 1);

      if (EQ (prop, intern ("foreground-color")))
	{
	  unsigned long new_color = load_color (f, val);
	  if (new_color != ~0)
	    {
	      FRAME_FOREGROUND_PIXEL (f) = new_color;
	      redraw = 1;
	      if (termscript)
		fprintf (termscript, "<FGCOLOR %lu>\n", new_color);
	    }
	}
      else if (EQ (prop, intern ("background-color")))
	{
	  unsigned long new_color = load_color (f, val);
	  if (new_color != ~0)
	    {
	      FRAME_BACKGROUND_PIXEL (f) = new_color;
	      redraw = 1;
	      if (termscript)
		fprintf (termscript, "<BGCOLOR %lu>\n", new_color);
	    }
	}
      else if (EQ (prop, intern ("menu-bar-lines")))
	x_set_menu_bar_lines (f, val, 0);
    }

  if (redraw)
    {
      extern void recompute_basic_faces (FRAME_PTR);
      extern void redraw_frame (FRAME_PTR);

      recompute_basic_faces (f);
      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");
  char *colors;

#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)
    {
      selected_frame->output_method = output_termcap;
      return;
    }

  Vwindow_system = intern ("pc");
  Vwindow_system_version = make_number (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.line_height = 1;
  the_only_x_display.font = (XFontStruct *)1;   /* must *not* be zero */

  init_frame_faces (selected_frame);

  ring_bell_hook = IT_ring_bell;
  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;
  change_line_highlight_hook = IT_change_line_highlight;
  update_begin_hook = IT_update_begin;
  update_end_hook = IT_update_end;
  reassert_line_highlight_hook = IT_reassert_line_highlight;
  frame_up_to_date_hook = IT_cmgoto; /* position cursor when update is done */

  /* 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;
#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 1;
#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 windows 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
 */

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

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


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 */
};

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