* keyboard.c (Qratio): New symbol.

[emacs.git] / src / msdos.c

/* MS-DOS specific C utilities.          -*- coding: raw-text -*-
   Copyright (C) 1993, 94, 95, 96, 97, 1999 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. */
#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 <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;
    }
}

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;
}

void
mouse_init ()
{
  union REGS regs;
  int b;

  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.  */
  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);
    }

  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 clock_t startup_time;

static int term_setup_done;

/* 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;

#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; illegal 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 y;
     int x;
     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
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 ();

  /* 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 ();
}

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);
  unsigned long fg, bg;

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

  /* Don't use invalid colors.  In particular, a color of -1 means use
     the colors of the default face, except that if highlight is on,
     invert the foreground and the background.  Note that we assume
     all 16 colors to be available for the background, since Emacs
     switches on this mode (and loses the blinking attribute) at
     startup.  */
  if (fg == (unsigned long)-1)
    fg = highlight || fp->tty_reverse_p ? FRAME_BACKGROUND_PIXEL (sf)
                                        : FRAME_FOREGROUND_PIXEL (sf);
  if (bg == (unsigned long)-1)
    bg = highlight || fp->tty_reverse_p ? FRAME_FOREGROUND_PIXEL (sf)
                                        : FRAME_BACKGROUND_PIXEL (sf);
  if (termscript)
    fprintf (termscript, "<FACE %d%s: %d/%d>",
             face, highlight ? "H" : "", fp->foreground, fp->background);
  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;

  struct coding_system *coding = (CODING_REQUIRE_ENCODING (&terminal_coding)
                                  ? &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);

  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[4], *buf;
      unsigned ch;
      register GLYPH g = GLYPH_FROM_CHAR_GLYPH (*str);

      /* Find the actual glyph to display by traversing the entire
         aliases chain for this glyph.  */
      GLYPH_FOLLOW_ALIASES (tbase, tlen, g);

      /* 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
        {
          /* Convert the character code to multibyte, if they
             requested display via language environment.  */
          ch = FAST_GLYPH_CHAR (g);
          /* We only want to convert unibyte characters to multibyte
             in unibyte buffers!  Otherwise, the 8-bit code might come
             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 (! GLYPH_CHAR_VALID_P (ch))
            {
              g = !NILP (Vdos_unsupported_char_glyph)
                ? Vdos_unsupported_char_glyph
                : MAKE_GLYPH (sf, '\177', GLYPH_FACE (sf, g));
              ch = FAST_GLYPH_CHAR (g);
            }
          if (COMPOSITE_CHAR_P (ch))
            {
              /* If CH is a composite character, we can display
                 only the first component.  */
              g = cmpchar_table[COMPOSITE_CHAR_ID (ch)]->glyph[0],
              ch = GLYPH_CHAR (sf, g);
              cf = FAST_GLYPH_FACE (g);
            }

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

          if (GLYPH_SIMPLE_P (tbase, tlen, g))
            /* We generate the multi-byte form of CH in BUF.  */
            chlen = CHAR_STRING (ch, workbuf, buf);
          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
            {
              encode_coding (coding, buf, conversion_buffer, chlen,
                             conversion_buffer_size);
              chlen -= coding->consumed;
              enclen = coding->produced;

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

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

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

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

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

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

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

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

  /* 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)
        {
          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;
        }
    }
}

static void
IT_clear_end_of_line (int first_unused)
{
  char *spaces, *sp;
  int i, j;
  int 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);
  if (termscript)
    fprintf (termscript, "<CLR:EOL>");
  i = (j = first_unused - new_pos_X) * 2;
  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>");
  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 (0);
    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
      && XFASTINT (XWINDOW (FRAME_MINIBUF_WINDOW (f))->top) <= 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_reassert_line_highlight (int new, int vpos)
{
  highlight = new;
}

static void
IT_change_line_highlight (int new_highlight, int y, int vpos, int first_unused_hpos)
{
  highlight = new_highlight;
  IT_cursor_to (vpos, 0);
  IT_clear_end_of_line (first_unused_hpos);
}

static void
IT_update_begin (struct frame *foo)
{
  highlight = 0;
}

static void
IT_update_end (struct frame *foo)
{
}

/* 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 xfns.c  */

Lisp_Object Qbackground_color;
Lisp_Object Qforeground_color;
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>");
  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;

#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;
  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;

  /* 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.  */

static int initial_screen_colors[2];

DEFUN ("msdos-remember-default-colors", Fmsdos_remember_default_colors,
       Smsdos_remember_default_colors, 1, 1, 0,
  "Remember the screen colors of the current frame.")
     (frame)
     Lisp_Object frame;
{
  int reverse;
  struct frame *f;

  CHECK_FRAME (frame, 0);
  f= XFRAME (frame);
  reverse = EQ (Fcdr (Fassq (intern ("reverse"), f->param_alist)), Qt);

  initial_screen_colors[0]
    = reverse ? FRAME_BACKGROUND_PIXEL (f) : FRAME_FOREGROUND_PIXEL (f);
  initial_screen_colors[1]
    = reverse ? FRAME_FOREGROUND_PIXEL (f) : FRAME_BACKGROUND_PIXEL (f);
}

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

  /* 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);

  /* 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], 1);
      values[i] = Fcdr (elt);
      i++;
    }

  j = i;

  for (i = 0; i < j; i++)
    {
      Lisp_Object prop = parms[i];
      Lisp_Object val  = values[i];

      if (EQ (prop, qreverse))
        reverse = EQ (val, Qt);
    }
        
  if (termscript && reverse && !was_reverse)
    fprintf (termscript, "<INVERSE-VIDEO>\n");

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

      if (EQ (prop, Qforeground_color))
        {
          unsigned long new_color = load_color (f, NULL, val, reverse
                                                ? LFACE_BACKGROUND_INDEX
                                                : LFACE_FOREGROUND_INDEX);
          if (new_color != ~0)
            {
              if (reverse)
                /* FIXME: should the fore-/background of the default
                   face change here as well?  */
                FRAME_BACKGROUND_PIXEL (f) = new_color;
              else
                FRAME_FOREGROUND_PIXEL (f) = new_color;
              redraw = 1;
              fg_set = 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, reverse
                                                ? LFACE_FOREGROUND_INDEX
                                                : LFACE_BACKGROUND_INDEX);
          if (new_color != ~0)
            {
              if (reverse)
                FRAME_FOREGROUND_PIXEL (f) = new_color;
              else
                FRAME_BACKGROUND_PIXEL (f) = new_color;
              redraw = 1;
              bg_set = 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", XSTRING (val)->data);
        }
      store_frame_param (f, prop, val);
    }

  /* If they specified "reverse", but not the colors, we need to swap
     the current frame colors.  */
  if (reverse && !was_reverse)
    {
      if (!fg_set)
        {
          FRAME_BACKGROUND_PIXEL (f) = orig_fg;
          redraw = 1;
        }
      if (!bg_set)
        {
          FRAME_FOREGROUND_PIXEL (f) = orig_bg;
          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");
  char *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.line_height = 1;
  the_only_x_display.font = (XFontStruct *)1;   /* must *not* be zero */

  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;
  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;
  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 */
  "ý&‚\",(-Š_€…)=  azertyuiop^$   qsdfghjklm—*   wxcvbnm;:!  ",
/* 0123456789012345678901234567890123456789012345678901234 */
  " 1234567890ø+  AZERTYUIOPùœ   QSDFGHJKLM%æ   WXCVBN?./õ  ",
/* 01234567 89012345678901234567890123456789012345678901234 */
  "  ~#{[|`\\^@]}             Ï                              ",
  0                             /* no translate table */
};

/*
 * Italian keyboard support, country code 39.
 * '<' 56:3c*0000
 * '>' 56:3e*0000
 * added also {,},` as, respectively, AltGr-8, AltGr-9, AltGr-'
 * Donated by Stefano Brozzi <brozzis@mag00.cedi.unipr.it>
 */

static struct kbd_translate it_kbd_translate_table[] = {
  { 0x56, 0x3c, Normal | 13 },
  { 0x56, 0x3e, Normal | 27 },
  { 0, 0, 0 }
};
static struct dos_keyboard_map it_keyboard = {
/* 0          1         2         3         4         5     */
/* 0 123456789012345678901234567890123456789012345678901234 */
  "\\1234567890'�< qwertyuiopŠ+>  asdfghjkl•…—   zxcvbnm,.-  ",
/* 01 23456789012345678901234567890123456789012345678901234 */
  "|!\"œ$%&/()=?^> QWERTYUIOP‚*   ASDFGHJKL‡øõ   ZXCVBNM;:_  ",
/* 0123456789012345678901234567890123456789012345678901234 */
  "        {}~`             []             @#               ",
  it_kbd_translate_table
};

static struct dos_keyboard_map dk_keyboard = {
/* 0         1         2         3         4         5      */
/* 0123456789012345678901234567890123456789012345678901234 */
  "«1234567890+|  qwertyuiop†~   asdfghjkl‘›'   zxcvbnm,.-  ",
/* 01 23456789012345678901234567890123456789012345678901234 */
  "õ!\"#$%&/()=?`  QWERTYUIOP�^   ASDFGHJKL’�*   ZXCVBNM;:_  ",
/* 0123456789012345678901234567890123456789012345678901234 */
  "  @œ$  {[]} |                                             ",
  0                             /* no translate table */
};

static struct kbd_translate jp_kbd_translate_table[] = {
  { 0x73, 0x5c, Normal | 0 },
  { 0x73, 0x5f, Normal | 0 },
  { 0x73, 0x1c, Map | 0 },
  { 0x7d, 0x5c, Normal | 13 },
  { 0x7d, 0x7c, Normal | 13 },
  { 0x7d, 0x1c, Map | 13 },
  { 0, 0, 0 }
};
static struct dos_keyboard_map jp_keyboard = {
/*  0         1          2         3         4         5     */
/*  0123456789012 345678901234567890123456789012345678901234 */
  "\\1234567890-^\\ qwertyuiop@[   asdfghjkl;:]   zxcvbnm,./  ",
/*  01 23456789012345678901234567890123456789012345678901234 */
   "_!\"#$%&'()~=~| QWERTYUIOP`{   ASDFGHJKL+*}   ZXCVBNM<>?  ",
  0,                            /* no Alt-Gr key */
  jp_kbd_translate_table
};

static struct keyboard_layout_list
{
  int country_code;
  struct dos_keyboard_map *keyboard_map;
} keyboard_layout_list[] =
{
  1, &us_keyboard,
  33, &fr_keyboard,
  39, &it_keyboard,
  45, &dk_keyboard,
  81, &jp_keyboard
};

static struct dos_keyboard_map *keyboard;
static int keyboard_map_all;
static int international_keyboard;

int
dos_set_keyboard (code, always)
     int code;
     int always;
{
  int i;
  _go32_dpmi_registers regs;

  /* See if Keyb.Com is installed (for international keyboard support).
     Note: calling Int 2Fh via int86 wedges the DOS box on some versions
     of Windows 9X!  So don't do that!  */
  regs.x.ax = 0xad80;
  regs.x.ss = regs.x.sp = regs.x.flags = 0;
  _go32_dpmi_simulate_int (0x2f, &regs);
  if (regs.h.al == 0xff)
    international_keyboard = 1;

  /* Initialize to US settings, for countries that don't have their own.  */
  keyboard = keyboard_layout_list[0].keyboard_map;
  keyboard_map_all = always;
  dos_keyboard_layout = 1;
  
  for (i = 0; i < (sizeof (keyboard_layout_list)/sizeof (struct keyboard_layout_list)); i++)
    if (code == keyboard_layout_list[i].country_code)
      {
        keyboard = keyboard_layout_list[i].keyboard_map;
        keyboard_map_all = always;
        dos_keyboard_layout = code;
        return 1;
      }
  return 0;
}
\f
static struct
{
  unsigned char char_code;      /* normal code  */
  unsigned char meta_code;      /* M- code      */
  unsigned char keypad_code;    /* keypad code  */
  unsigned char editkey_code;   /* edit key     */
} keypad_translate_map[] = {
  '0',  '0',  0xb0, /* kp-0 */          0x63, /* insert */
  '1',  '1',  0xb1, /* kp-1 */          0x57, /* end */
  '2',  '2',  0xb2, /* kp-2 */          0x54, /* down */
  '3',  '3',  0xb3, /* kp-3 */          0x56, /* next */
  '4',  '4',  0xb4, /* kp-4 */          0x51, /* left */
  '5',  '5',  0xb5, /* kp-5 */          0xb5, /* kp-5 */
  '6',  '6',  0xb6, /* kp-6 */          0x53, /* right */
  '7',  '7',  0xb7, /* kp-7 */          0x50, /* home */
  '8',  '8',  0xb8, /* kp-8 */          0x52, /* up */
  '9',  '9',  0xb9, /* kp-9 */          0x55, /* prior */
  '.',  '-',  0xae, /* kp-decimal */    0xff  /* delete */
};

static struct
{
  unsigned char char_code;      /* normal code  */
  unsigned char keypad_code;    /* keypad code  */
} grey_key_translate_map[] = {
  '/',  0xaf, /* kp-decimal */
  '*',  0xaa, /* kp-multiply */
  '-',  0xad, /* kp-subtract */
  '+',  0xab, /* kp-add */
  '\r', 0x8d  /* kp-enter */
};

static unsigned short
ibmpc_translate_map[] =
{
  /* --------------- 00 to 0f --------------- */
  Normal | 0xff,        /* Ctrl Break + Alt-NNN */
  Alt | ModFct | 0x1b,          /* Escape */
  Normal | 1,                   /* '1' */
  Normal | 2,                   /* '2' */
  Normal | 3,                   /* '3' */
  Normal | 4,                   /* '4' */
  Normal | 5,                   /* '5' */
  Normal | 6,                   /* '6' */
  Normal | 7,                   /* '7' */
  Normal | 8,                   /* '8' */
  Normal | 9,                   /* '9' */
  Normal | 10,                  /* '0' */
  Normal | 11,                  /* '-' */
  Normal | 12,                  /* '=' */
  Special | 0x08,               /* Backspace */
  ModFct | 0x74,                /* Tab/Backtab */

  /* --------------- 10 to 1f --------------- */
  Map | 15,                     /* 'q' */
  Map | 16,                     /* 'w' */
  Map | 17,                     /* 'e' */
  Map | 18,                     /* 'r' */
  Map | 19,                     /* 't' */
  Map | 20,                     /* 'y' */
  Map | 21,                     /* 'u' */
  Map | 22,                     /* 'i' */
  Map | 23,                     /* 'o' */
  Map | 24,                     /* 'p' */
  Map | 25,                     /* '[' */
  Map | 26,                     /* ']' */ 
  ModFct | 0x0d,                /* Return */
  Ignore,                       /* Ctrl */
  Map | 30,                     /* 'a' */
  Map | 31,                     /* 's' */

  /* --------------- 20 to 2f --------------- */
  Map | 32,                     /* 'd' */
  Map | 33,                     /* 'f' */
  Map | 34,                     /* 'g' */
  Map | 35,                     /* 'h' */
  Map | 36,                     /* 'j' */
  Map | 37,                     /* 'k' */
  Map | 38,                     /* 'l' */
  Map | 39,                     /* ';' */
  Map | 40,                     /* '\'' */
  Map |  0,                     /* '`' */
  Ignore,                       /* Left shift */
  Map | 41,                     /* '\\' */
  Map | 45,                     /* 'z' */
  Map | 46,                     /* 'x' */
  Map | 47,                     /* 'c' */
  Map | 48,                     /* 'v' */

  /* --------------- 30 to 3f --------------- */
  Map | 49,                     /* 'b' */
  Map | 50,                     /* 'n' */
  Map | 51,                     /* 'm' */
  Map | 52,                     /* ',' */
  Map | 53,                     /* '.' */
  Map | 54,                     /* '/' */
  Ignore,                       /* Right shift */
  Grey | 1,                     /* Grey * */
  Ignore,                       /* Alt */
  Normal | 55,                  /* ' ' */
  Ignore,                       /* Caps Lock */
  FctKey | 0xbe,                /* F1 */
  FctKey | 0xbf,                /* F2 */
  FctKey | 0xc0,                /* F3 */
  FctKey | 0xc1,                /* F4 */
  FctKey | 0xc2,                /* F5 */

  /* --------------- 40 to 4f --------------- */
  FctKey | 0xc3,                /* F6 */
  FctKey | 0xc4,                /* F7 */
  FctKey | 0xc5,                /* F8 */
  FctKey | 0xc6,                /* F9 */
  FctKey | 0xc7,                /* F10 */
  Ignore,                       /* Num Lock */
  Ignore,                       /* Scroll Lock */
  KeyPad | 7,                   /* Home */
  KeyPad | 8,                   /* Up */
  KeyPad | 9,                   /* Page Up */
  Grey | 2,                     /* Grey - */
  KeyPad | 4,                   /* Left */
  KeyPad | 5,                   /* Keypad 5 */
  KeyPad | 6,                   /* Right */
  Grey | 3,                     /* Grey + */
  KeyPad | 1,                   /* End */

  /* --------------- 50 to 5f --------------- */
  KeyPad | 2,                   /* Down */
  KeyPad | 3,                   /* Page Down */
  KeyPad | 0,                   /* Insert */
  KeyPad | 10,                  /* Delete */
  Shift | FctKey | 0xbe,        /* (Shift) F1 */
  Shift | FctKey | 0xbf,        /* (Shift) F2 */
  Shift | FctKey | 0xc0,        /* (Shift) F3 */
  Shift | FctKey | 0xc1,        /* (Shift) F4 */
  Shift | FctKey | 0xc2,        /* (Shift) F5 */
  Shift | FctKey | 0xc3,        /* (Shift) F6 */
  Shift | FctKey | 0xc4,        /* (Shift) F7 */
  Shift | FctKey | 0xc5,        /* (Shift) F8 */
  Shift | FctKey | 0xc6,        /* (Shift) F9 */
  Shift | FctKey | 0xc7,        /* (Shift) F10 */
  Ctrl | FctKey | 0xbe,         /* (Ctrl) F1 */
  Ctrl | FctKey | 0xbf,         /* (Ctrl) F2 */

  /* --------------- 60 to 6f --------------- */
  Ctrl | FctKey | 0xc0,         /* (Ctrl) F3 */
  Ctrl | FctKey | 0xc1,         /* (Ctrl) F4 */
  Ctrl | FctKey | 0xc2,         /* (Ctrl) F5 */
  Ctrl | FctKey | 0xc3,         /* (Ctrl) F6 */
  Ctrl | FctKey | 0xc4,         /* (Ctrl) F7 */
  Ctrl | FctKey | 0xc5,         /* (Ctrl) F8 */
  Ctrl | FctKey | 0xc6,         /* (Ctrl) F9 */
  Ctrl | FctKey | 0xc7,         /* (Ctrl) F10 */
  Alt | FctKey | 0xbe,          /* (Alt) F1 */
  Alt | FctKey | 0xbf,          /* (Alt) F2 */
  Alt | FctKey | 0xc0,          /* (Alt) F3 */
  Alt | FctKey | 0xc1,          /* (Alt) F4 */
  Alt | FctKey | 0xc2,          /* (Alt) F5 */
  Alt | FctKey | 0xc3,          /* (Alt) F6 */
  Alt | FctKey | 0xc4,          /* (Alt) F7 */
  Alt | FctKey | 0xc5,          /* (Alt) F8 */

  /* --------------- 70 to 7f --------------- */
  Alt | FctKey | 0xc6,          /* (Alt) F9 */
  Alt | FctKey | 0xc7,          /* (Alt) F10 */
  Ctrl | FctKey | 0x6d,         /* (Ctrl) Sys Rq */
  Ctrl | KeyPad | 4,            /* (Ctrl) Left */
  Ctrl | KeyPad | 6,            /* (Ctrl) Right */
  Ctrl | KeyPad | 1,            /* (Ctrl) End */
  Ctrl | KeyPad | 3,            /* (Ctrl) Page Down */
  Ctrl | KeyPad | 7,            /* (Ctrl) Home */
  Alt | Map | 1,                /* '1' */
  Alt | Map | 2,                /* '2' */
  Alt | Map | 3,                /* '3' */
  Alt | Map | 4,                /* '4' */
  Alt | Map | 5,                /* '5' */
  Alt | Map | 6,                /* '6' */
  Alt | Map | 7,                /* '7' */
  Alt | Map | 8,                /* '8' */

  /* --------------- 80 to 8f --------------- */
  Alt | Map | 9,                /* '9' */
  Alt | Map | 10,               /* '0' */
  Alt | Map | 11,               /* '-' */
  Alt | Map | 12,               /* '=' */
  Ctrl | KeyPad | 9,            /* (Ctrl) Page Up */
  FctKey | 0xc8,                /* F11 */
  FctKey | 0xc9,                /* F12 */
  Shift | FctKey | 0xc8,        /* (Shift) F11 */
  Shift | FctKey | 0xc9,        /* (Shift) F12 */
  Ctrl | FctKey | 0xc8,         /* (Ctrl) F11 */
  Ctrl | FctKey | 0xc9,         /* (Ctrl) F12 */
  Alt | FctKey | 0xc8,          /* (Alt) F11 */
  Alt | FctKey | 0xc9,          /* (Alt) F12 */
  Ctrl | KeyPad | 8,            /* (Ctrl) Up */
  Ctrl | Grey | 2,              /* (Ctrl) Grey - */
  Ctrl | KeyPad | 5,            /* (Ctrl) Keypad 5 */

  /* --------------- 90 to 9f --------------- */
  Ctrl | Grey | 3,              /* (Ctrl) Grey + */
  Ctrl | KeyPad | 2,            /* (Ctrl) Down */
  Ctrl | KeyPad | 0,            /* (Ctrl) Insert */
  Ctrl | KeyPad | 10,           /* (Ctrl) Delete */
  Ctrl | FctKey | 0x09,         /* (Ctrl) Tab */
  Ctrl | Grey | 0,              /* (Ctrl) Grey / */
  Ctrl | Grey | 1,              /* (Ctrl) Grey * */
  Alt | FctKey | 0x50,          /* (Alt) Home */
  Alt | FctKey | 0x52,          /* (Alt) Up */
  Alt | FctKey | 0x55,          /* (Alt) Page Up */
  Ignore,                       /* NO KEY */
  Alt | FctKey | 0x51,          /* (Alt) Left */
  Ignore,                       /* NO KEY */
  Alt | FctKey | 0x53,          /* (Alt) Right */
  Ignore,                       /* NO KEY */
  Alt | FctKey | 0x57,          /* (Alt) End */

  /* --------------- a0 to af --------------- */
  Alt | KeyPad | 2,             /* (Alt) Down */
  Alt | KeyPad | 3,             /* (Alt) Page Down */
  Alt | KeyPad | 0,             /* (Alt) Insert */
  Alt | KeyPad | 10,            /* (Alt) Delete */
  Alt | Grey | 0,               /* (Alt) Grey / */
  Alt | FctKey | 0x09,          /* (Alt) Tab */
  Alt | Grey | 4                /* (Alt) Keypad Enter */
};
\f
/* These bit-positions corresponds to values returned by BIOS */
#define SHIFT_P         0x0003  /* two bits! */
#define CTRL_P          0x0004
#define ALT_P           0x0008
#define SCRLOCK_P       0x0010
#define NUMLOCK_P       0x0020
#define CAPSLOCK_P      0x0040
#define ALT_GR_P        0x0800
#define SUPER_P         0x4000  /* pseudo */
#define HYPER_P         0x8000  /* pseudo */

static int
dos_get_modifiers (keymask)
     int *keymask;
{
  union REGS regs;
  int mask;
  int modifiers = 0;
  
  /* Calculate modifier bits */
  regs.h.ah = extended_kbd ? 0x12 : 0x02;
  int86 (0x16, &regs, &regs);

  if (!extended_kbd)
    {
      mask = regs.h.al & (SHIFT_P | CTRL_P | ALT_P | 
                          SCRLOCK_P | NUMLOCK_P | CAPSLOCK_P);
    }
  else
    {
      mask = regs.h.al & (SHIFT_P |
                          SCRLOCK_P | NUMLOCK_P | CAPSLOCK_P);
  
      /* Do not break international keyboard support.   */
      /* When Keyb.Com is loaded, the right Alt key is  */
      /* used for accessing characters like { and }       */
      if (regs.h.ah & 2)                /* Left ALT pressed ? */
        mask |= ALT_P;

      if ((regs.h.ah & 8) != 0)         /* Right ALT pressed ? */
        {
          mask |= ALT_GR_P;
          if (dos_hyper_key == 1)
            {
              mask |= HYPER_P;
              modifiers |= hyper_modifier;
            }
          else if (dos_super_key == 1)
            {
              mask |= SUPER_P;
              modifiers |= super_modifier;
            }
          else if (!international_keyboard)
            {
              /* If Keyb.Com is NOT installed, let Right Alt behave
                 like the Left Alt.  */
              mask &= ~ALT_GR_P;
              mask |= ALT_P;
            }
        }
      
      if (regs.h.ah & 1)                /* Left CTRL pressed ? */
        mask |= CTRL_P;

      if (regs.h.ah & 4)                /* Right CTRL pressed ? */
        {
          if (dos_hyper_key == 2)
            {
              mask |= HYPER_P;
              modifiers |= hyper_modifier;
            }
          else if (dos_super_key == 2)
            {
              mask |= SUPER_P;
              modifiers |= super_modifier;
            }
          else
            mask |= CTRL_P;
        }
    }

  if (mask & SHIFT_P)
    modifiers |= shift_modifier;
  if (mask & CTRL_P)
    modifiers |= ctrl_modifier;
  if (mask & ALT_P)
    modifiers |= meta_modifier;

  if (keymask)
    *keymask = mask;
  return modifiers;
}

#define NUM_RECENT_DOSKEYS (100)
int recent_doskeys_index;       /* Index for storing next element into recent_doskeys */
int total_doskeys;              /* Total number of elements stored into recent_doskeys */
Lisp_Object recent_doskeys; /* A vector, holding the last 100 keystrokes */

DEFUN ("recent-doskeys", Frecent_doskeys, Srecent_doskeys, 0, 0, 0,
  "Return vector of last 100 keyboard input values seen in dos_rawgetc.\n\
Each input key receives two values in this vector: first the ASCII code,\n\
and then the scan code.")
     ()
{
  Lisp_Object *keys = XVECTOR (recent_doskeys)->contents;
  Lisp_Object val;

  if (total_doskeys < NUM_RECENT_DOSKEYS)
    return Fvector (total_doskeys, keys);
  else
    {
      val = Fvector (NUM_RECENT_DOSKEYS, keys);
      bcopy (keys + recent_doskeys_index,
             XVECTOR (val)->contents,
             (NUM_RECENT_DOSKEYS - recent_doskeys_index) * sizeof (Lisp_Object));
      bcopy (keys,
             XVECTOR (val)->contents + NUM_RECENT_DOSKEYS - recent_doskeys_index,
             recent_doskeys_index * sizeof (Lisp_Object));
      return val;
    }
}

/* Get a char from keyboard.  Function keys are put into the event queue.  */

extern void kbd_buffer_store_event (struct input_event *);
static int mouse_preempted = 0; /* non-zero when XMenu gobbles mouse events */

static int
dos_rawgetc ()
{
  struct input_event event;
  union REGS regs;
  
#ifndef HAVE_X_WINDOWS
  /* Maybe put the cursor where it should be.  */
  IT_cmgoto (SELECTED_FRAME());
#endif

  /* The following condition is equivalent to `kbhit ()', except that
     it uses the bios to do its job.  This pleases DESQview/X.  */
  while ((regs.h.ah = extended_kbd ? 0x11 : 0x01),
         int86 (0x16, &regs, &regs),
         (regs.x.flags & 0x40) == 0)
    {
      union REGS regs;
      register unsigned char c;
      int sc, code = -1, mask, kp_mode;
      int modifiers;

      regs.h.ah = extended_kbd ? 0x10 : 0x00;
      int86 (0x16, &regs, &regs);
      c = regs.h.al;
      sc = regs.h.ah;

      total_doskeys += 2;
      XVECTOR (recent_doskeys)->contents[recent_doskeys_index++]
        = make_number (c);
      if (recent_doskeys_index == NUM_RECENT_DOSKEYS)
        recent_doskeys_index = 0;
      XVECTOR (recent_doskeys)->contents[recent_doskeys_index++]
        = make_number (sc);
      if (recent_doskeys_index == NUM_RECENT_DOSKEYS)
        recent_doskeys_index = 0;

      modifiers = dos_get_modifiers (&mask);
      
#ifndef HAVE_X_WINDOWS
      if (!NILP (Vdos_display_scancodes))
        {
          char buf[11];
          sprintf (buf, "%02x:%02x*%04x",
                   (unsigned) (sc&0xff), (unsigned) c, mask);
          dos_direct_output (screen_size_Y - 2, screen_size_X - 12, buf, 10);
        }
#endif

      if (sc == 0xe0)
        {
          switch (c)
            {
            case 10:            /* Ctrl Grey Enter */
              code = Ctrl | Grey | 4;
              break;
            case 13:            /* Grey Enter */
              code = Grey | 4;
              break;
            case '/':           /* Grey / */
              code = Grey | 0;
              break;
            default:
              continue;
            };
          c = 0;
        }
      else
        {
          /* Try the keyboard-private translation table first.  */
          if (keyboard->translate_table)
            {
              struct kbd_translate *p = keyboard->translate_table;

              while (p->sc)
                {
                  if (p->sc == sc && p->ch == c)
                    {
                      code = p->code;
                      break;
                    }
                  p++;
                }
            }
          /* If the private table didn't translate it, use the general
             one.  */
          if (code == -1)
            {
              if (sc >= (sizeof (ibmpc_translate_map) / sizeof (short)))
                continue;
              if ((code = ibmpc_translate_map[sc]) == Ignore)
                continue;
            }
        }
      
      if (c == 0)
        {
        /* We only look at the keyboard Ctrl/Shift/Alt keys when
           Emacs is ready to read a key.  Therefore, if they press
           `Alt-x' when Emacs is busy, by the time we get to
           `dos_get_modifiers', they might have already released the
           Alt key, and Emacs gets just `x', which is BAD.
           However, for keys with the `Map' property set, the ASCII
           code returns zero iff Alt is pressed.  So, when we DON'T
           have to support international_keyboard, we don't have to
           distinguish between the left and  right Alt keys, and we
           can set the META modifier for any keys with the `Map'
           property if they return zero ASCII code (c = 0).  */
        if ( (code & Alt)
             || ( (code & 0xf000) == Map && !international_keyboard))
            modifiers |= meta_modifier;
          if (code & Ctrl)
            modifiers |= ctrl_modifier;
          if (code & Shift)
            modifiers |= shift_modifier;
        }
      
      switch (code & 0xf000)
        {
        case ModFct:
          if (c && !(mask & (SHIFT_P | ALT_P | CTRL_P | HYPER_P | SUPER_P)))
            return c;
          c = 0;                /* Special */
          
        case FctKey:
          if (c != 0)
            return c;
            
        case Special:
          code |= 0xff00;
          break;
          
        case Normal:
          if (sc == 0)
            {
              if (c == 0)       /* ctrl-break */
                continue;
              return c;         /* ALT-nnn */
            }
          if (!keyboard_map_all)
            {
              if (c != ' ')
                return c;
              code = c;
              break;
            }
          
        case Map:
          if (c && !(mask & ALT_P) && !((mask & SHIFT_P) && (mask & CTRL_P)))
            if (!keyboard_map_all)
              return c;

          code &= 0xff;
          if (mask & ALT_P && code <= 10 && code > 0 && dos_keypad_mode & 0x200)
            mask |= SHIFT_P;    /* ALT-1 => M-! etc. */
          
          if (mask & SHIFT_P)
            {
              code = keyboard->shifted[code];
              mask -= SHIFT_P;
              modifiers &= ~shift_modifier;
            }
          else
            if ((mask & ALT_GR_P) && keyboard->alt_gr && keyboard->alt_gr[code] != ' ')
              code = keyboard->alt_gr[code];
            else
              code = keyboard->unshifted[code];
          break;

        case KeyPad:
          code &= 0xff;
          if (c == 0xe0)        /* edit key */
            kp_mode = 3;
          else
            if ((mask & (NUMLOCK_P|CTRL_P|SHIFT_P|ALT_P)) == NUMLOCK_P) /* numlock on */
              kp_mode = dos_keypad_mode & 0x03;
            else
              kp_mode = (dos_keypad_mode >> 4) & 0x03;
          
          switch (kp_mode)
            {
            case 0:
              if (code == 10 && dos_decimal_point)
                return dos_decimal_point;
              return keypad_translate_map[code].char_code;

            case 1:
              code = 0xff00 | keypad_translate_map[code].keypad_code;
              break;

            case 2:
              code = keypad_translate_map[code].meta_code;
              modifiers = meta_modifier;
              break;
              
            case 3:
              code = 0xff00 | keypad_translate_map[code].editkey_code;
              break;
            }
          break;
          
        case Grey:
          code &= 0xff;
          kp_mode = ((mask & (NUMLOCK_P|CTRL_P|SHIFT_P|ALT_P)) == NUMLOCK_P) ? 0x04 : 0x40;
          if (dos_keypad_mode & kp_mode)
            code = 0xff00 | grey_key_translate_map[code].keypad_code;
          else
            code = grey_key_translate_map[code].char_code;
          break;
        }
      
    make_event:
      if (code == 0)
        continue;
      
      if (code >= 0x100)
        event.kind = non_ascii_keystroke;
      else
        event.kind = ascii_keystroke;
      event.code = code;
      event.modifiers = modifiers;
      event.frame_or_window = selected_frame;
      event.timestamp = event_timestamp ();
      kbd_buffer_store_event (&event);
    }

  if (have_mouse > 0 && !mouse_preempted)
    {
      int but, press, x, y, ok;

      /* Check for mouse movement *before* buttons.  */
      mouse_check_moved ();

      for (but = 0; but < NUM_MOUSE_BUTTONS; but++)
        for (press = 0; press < 2; press++)
          {
            int button_num = but;

            if (press)
              ok = mouse_pressed (but, &x, &y);
            else
              ok = mouse_released (but, &x, &y);
            if (ok)
              {
                /* Allow a simultaneous press/release of Mouse-1 and
                   Mouse-2 to simulate Mouse-3 on two-button mice.  */
                if (mouse_button_count == 2 && but < 2)
                  {
                    int x2, y2; /* don't clobber original coordinates */

                    /* If only one button is pressed, wait 100 msec and
                       check again.  This way, Speedy Gonzales isn't
                       punished, while the slow get their chance.  */
                    if (press && mouse_pressed (1-but, &x2, &y2)
                        || !press && mouse_released (1-but, &x2, &y2))
                      button_num = 2;
                    else
                      {
                        delay (100);
                        if (press && mouse_pressed (1-but, &x2, &y2)
                            || !press && mouse_released (1-but, &x2, &y2))
                          button_num = 2;
                      }
                  }

                event.kind = mouse_click;
                event.code = button_num;
                event.modifiers = dos_get_modifiers (0)
                  | (press ? down_modifier : up_modifier);
                event.x = x;
                event.y = y;
                event.frame_or_window = selected_frame;
                event.timestamp = event_timestamp ();
                kbd_buffer_store_event (&event);
              }
          }
    }

  return -1;
}

static int prev_get_char = -1;

/* Return 1 if a key is ready to be read without suspending execution.  */

dos_keysns ()
{
  if (prev_get_char != -1)
    return 1;
  else
    return ((prev_get_char = dos_rawgetc ()) != -1);
}

/* Read a key.  Return -1 if no key is ready.  */

dos_keyread ()
{
  if (prev_get_char != -1)
    {
      int c = prev_get_char;
      prev_get_char = -1;
      return c;
    }
  else
    return dos_rawgetc ();
}
\f
#ifndef HAVE_X_WINDOWS
/* See xterm.c for more info.  */
void
pixel_to_glyph_coords (f, pix_x, pix_y, x, y, bounds, noclip)
     FRAME_PTR f;
     register int pix_x, pix_y;
     register int *x, *y;
     XRectangle *bounds;
     int noclip;
{
  if (bounds) abort ();

  /* Ignore clipping.  */

  *x = pix_x;
  *y = pix_y;
}

void
glyph_to_pixel_coords (f, x, y, pix_x, pix_y)
     FRAME_PTR f;
     register int x, y;
     register int *pix_x, *pix_y;
{
  *pix_x = x;
  *pix_y = y;
}
\f
/* Simulation of X's menus.  Nothing too fancy here -- just make it work
   for now.

   Actually, I don't know the meaning of all the parameters of the functions
   here -- I only know how they are called by xmenu.c.  I could of course
   grab the nearest Xlib manual (down the hall, second-to-last door on the
   left), but I don't think it's worth the effort.  */

static XMenu *
IT_menu_create ()
{
  XMenu *menu;

  menu = (XMenu *) xmalloc (sizeof (XMenu));
  menu->allocated = menu->count = menu->panecount = menu->width = 0;
  return menu;
}

/* Allocate some (more) memory for MENU ensuring that there is room for one
   for item.  */

static void
IT_menu_make_room (XMenu *menu)
{
  if (menu->allocated == 0)
    {
      int count = menu->allocated = 10;
      menu->text = (char **) xmalloc (count * sizeof (char *));
      menu->submenu = (XMenu **) xmalloc (count * sizeof (XMenu *));
      menu->panenumber = (int *) xmalloc (count * sizeof (int));
    }
  else if (menu->allocated == menu->count)
    {
      int count = menu->allocated = menu->allocated + 10;
      menu->text
        = (char **) xrealloc (menu->text, count * sizeof (char *));
      menu->submenu
        = (XMenu **) xrealloc (menu->submenu, count * sizeof (XMenu *));
      menu->panenumber
        = (int *) xrealloc (menu->panenumber, count * sizeof (int));
    }
}

/* Search the given menu structure for a given pane number.  */

static XMenu *
IT_menu_search_pane (XMenu *menu, int pane)
{
  int i;
  XMenu *try;

  for (i = 0; i < menu->count; i++)
    if (menu->submenu[i])
      {
        if (pane == menu->panenumber[i])
          return menu->submenu[i];
        if ((try = IT_menu_search_pane (menu->submenu[i], pane)))
          return try;
      }
  return (XMenu *) 0;
}

/* Determine how much screen space a given menu needs.  */

static void
IT_menu_calc_size (XMenu *menu, int *width, int *height)
{
  int i, h2, w2, maxsubwidth, maxheight;

  maxsubwidth = 0;
  maxheight = menu->count;
  for (i = 0; i < menu->count; i++)
    {
      if (menu->submenu[i])
        {
          IT_menu_calc_size (menu->submenu[i], &w2, &h2);
          if (w2 > maxsubwidth) maxsubwidth = w2;
          if (i + h2 > maxheight) maxheight = i + h2;
        }
    }
  *width = menu->width + maxsubwidth;
  *height = maxheight;
}

/* Display MENU at (X,Y) using FACES.  */

static void
IT_menu_display (XMenu *menu, int y, int x, int *faces)
{
  int i, j, face, width;
  struct glyph *text, *p;
  char *q;
  int mx, my;
  int enabled, mousehere;
  int row, col;
  struct frame *sf = SELECTED_FRAME();

  width = menu->width;
  text = (struct glyph *) xmalloc ((width + 2) * sizeof (struct glyph));
  ScreenGetCursor (&row, &col);
  mouse_get_xy (&mx, &my);
  IT_update_begin (sf);
  for (i = 0; i < menu->count; i++)
    {
      IT_cursor_to (y + i, x);
      enabled
        = (!menu->submenu[i] && menu->panenumber[i]) || (menu->submenu[i]);
      mousehere = (y + i == my && x <= mx && mx < x + width + 2);
      face = faces[enabled + mousehere * 2];
      p = text;
      SET_CHAR_GLYPH (*p, ' ', face, 0);
      p++;
      for (j = 0, q = menu->text[i]; *q; j++)
        {
          if (*q > 26)
            {
              SET_CHAR_GLYPH (*p, *q++, face, 0);
              p++;
            }
          else  /* make '^x' */
            {
              SET_CHAR_GLYPH (*p, '^', face, 0);
              p++;
              j++;
              SET_CHAR_GLYPH (*p, *q++ + 64, face, 0);
              p++;
            }
        }
            
      for (; j < width; j++, p++)
        SET_CHAR_GLYPH (*p, ' ', face, 0);

      SET_CHAR_GLYPH (*p, menu->submenu[i] ? 16 : ' ', face, 0);
      p++;
      IT_write_glyphs (text, width + 2);
    }
  IT_update_end (sf);
  IT_cursor_to (row, col);
  xfree (text);
}
\f
/* --------------------------- X Menu emulation ---------------------- */

/* Report availability of menus.  */

int
have_menus_p ()
{
  return 1;
}

/* Create a brand new menu structure.  */

XMenu *
XMenuCreate (Display *foo1, Window foo2, char *foo3)
{
  return IT_menu_create ();
}

/* Create a new pane and place it on the outer-most level.  It is not
   clear that it should be placed out there, but I don't know what else
   to do.  */

int
XMenuAddPane (Display *foo, XMenu *menu, char *txt, int enable)
{
  int len;
  char *p;

  if (!enable)
    abort ();

  IT_menu_make_room (menu);
  menu->submenu[menu->count] = IT_menu_create ();
  menu->text[menu->count] = txt;
  menu->panenumber[menu->count] = ++menu->panecount;
  menu->count++;

  /* Adjust length for possible control characters (which will
     be written as ^x).  */
  for (len = strlen (txt), p = txt; *p; p++)
    if (*p < 27)
      len++;

  if (len > menu->width)
    menu->width = len;

  return menu->panecount;
}

/* Create a new item in a menu pane.  */

int
XMenuAddSelection (Display *bar, XMenu *menu, int pane,
                   int foo, char *txt, int enable)
{
  int len;
  char *p;

  if (pane)
    if (!(menu = IT_menu_search_pane (menu, pane)))
      return XM_FAILURE;
  IT_menu_make_room (menu);
  menu->submenu[menu->count] = (XMenu *) 0;
  menu->text[menu->count] = txt;
  menu->panenumber[menu->count] = enable;
  menu->count++;

  /* Adjust length for possible control characters (which will
     be written as ^x).  */
  for (len = strlen (txt), p = txt; *p; p++)
    if (*p < 27)
      len++;

  if (len > menu->width)
    menu->width = len;

  return XM_SUCCESS;
}

/* Decide where the menu would be placed if requested at (X,Y).  */

void
XMenuLocate (Display *foo0, XMenu *menu, int foo1, int foo2, int x, int y,
             int *ulx, int *uly, int *width, int *height)
{
  IT_menu_calc_size (menu, width, height);
  *ulx = x + 1;
  *uly = y;
  *width += 2;
}

struct IT_menu_state
{
  void *screen_behind;
  XMenu *menu;
  int pane;
  int x, y;
};


/* Display menu, wait for user's response, and return that response.  */

int
XMenuActivate (Display *foo, XMenu *menu, int *pane, int *selidx,
               int x0, int y0, unsigned ButtonMask, char **txt)
{
  struct IT_menu_state *state;
  int statecount;
  int x, y, i, b;
  int screensize;
  int faces[4];
  Lisp_Object selectface;
  int leave, result, onepane;
  int title_faces[4];           /* face to display the menu title */
  int buffers_num_deleted = 0;
  struct frame *sf = SELECTED_FRAME();

  /* Just in case we got here without a mouse present...  */
  if (have_mouse <= 0)
    return XM_IA_SELECT;
  /* Don't allow non-positive x0 and y0, lest the menu will wrap
     around the display.  */
  if (x0 <= 0)
    x0 = 1;
  if (y0 <= 0)
    y0 = 1;

  /* We will process all the mouse events directly, so we had
     better prevented dos_rawgetc from stealing them from us.  */
  mouse_preempted++;

  state = alloca (menu->panecount * sizeof (struct IT_menu_state));
  screensize = screen_size * 2;
  faces[0]
    = lookup_derived_face (sf, intern ("msdos-menu-passive-face"),
                           CHARSET_ASCII, DEFAULT_FACE_ID);
  faces[1]
    = lookup_derived_face (sf, intern ("msdos-menu-active-face"),
                           CHARSET_ASCII, DEFAULT_FACE_ID);
  selectface = intern ("msdos-menu-select-face");
  faces[2] = lookup_derived_face (sf, selectface,
                                  CHARSET_ASCII, faces[0]);
  faces[3] = lookup_derived_face (sf, selectface,
                                  CHARSET_ASCII, faces[1]);

  /* Make sure the menu title is always displayed with
     `msdos-menu-active-face', no matter where the mouse pointer is.  */
  for (i = 0; i < 4; i++)
    title_faces[i] = faces[3];

  statecount = 1;

  /* Don't let the title for the "Buffers" popup menu include a
     digit (which is ugly).
     
     This is a terrible kludge, but I think the "Buffers" case is
     the only one where the title includes a number, so it doesn't
     seem to be necessary to make this more general.  */
  if (strncmp (menu->text[0], "Buffers 1", 9) == 0)
    {
      menu->text[0][7] = '\0';
      buffers_num_deleted = 1;
    }
  state[0].menu = menu;
  mouse_off ();
  ScreenRetrieve (state[0].screen_behind = xmalloc (screensize));

  /* Turn off the cursor.  Otherwise it shows through the menu
     panes, which is ugly.  */
  IT_display_cursor (0);

  IT_menu_display (menu, y0 - 1, x0 - 1, title_faces); /* display menu title */
  if (buffers_num_deleted)
    menu->text[0][7] = ' ';
  if ((onepane = menu->count == 1 && menu->submenu[0]))
    {
      menu->width = menu->submenu[0]->width;
      state[0].menu = menu->submenu[0];
    }
  else
    {
      state[0].menu = menu;
    }
  state[0].x = x0 - 1;
  state[0].y = y0;
  state[0].pane = onepane;

  mouse_last_x = -1;  /* A hack that forces display.  */
  leave = 0;
  while (!leave)
    {
      if (!mouse_visible) mouse_on ();
      mouse_check_moved ();
      if (sf->mouse_moved)
        {
          sf->mouse_moved = 0;
          result = XM_IA_SELECT;
          mouse_get_xy (&x, &y);
          for (i = 0; i < statecount; i++)
            if (state[i].x <= x && x < state[i].x + state[i].menu->width + 2)
              {
                int dy = y - state[i].y;
                if (0 <= dy && dy < state[i].menu->count)
                  {
                    if (!state[i].menu->submenu[dy])
                      if (state[i].menu->panenumber[dy])
                        result = XM_SUCCESS;
                      else
                        result = XM_IA_SELECT;
                    *pane = state[i].pane - 1;
                    *selidx = dy;
                    /* We hit some part of a menu, so drop extra menus that
                       have been opened.  That does not include an open and
                       active submenu.  */
                    if (i != statecount - 2
                        || state[i].menu->submenu[dy] != state[i+1].menu)
                      while (i != statecount - 1)
                        {
                          statecount--;
                          mouse_off ();
                          ScreenUpdate (state[statecount].screen_behind);
                          if (screen_virtual_segment)
                            dosv_refresh_virtual_screen (0, screen_size);
                          xfree (state[statecount].screen_behind);
                        }
                    if (i == statecount - 1 && state[i].menu->submenu[dy])
                      {
                        IT_menu_display (state[i].menu,
                                         state[i].y,
                                         state[i].x,
                                         faces);
                        state[statecount].menu = state[i].menu->submenu[dy];
                        state[statecount].pane = state[i].menu->panenumber[dy];
                        mouse_off ();
                        ScreenRetrieve (state[statecount].screen_behind
                                        = xmalloc (screensize));
                        state[statecount].x
                          = state[i].x + state[i].menu->width + 2;
                        state[statecount].y = y;
                        statecount++;                     
                      }
                  }
              }
          IT_menu_display (state[statecount - 1].menu,
                           state[statecount - 1].y,
                           state[statecount - 1].x,
                           faces);
        }
      else
        /* We are busy-waiting for the mouse to move, so let's be nice
           to other Windows applications by releasing our time slice.  */
        __dpmi_yield ();
      for (b = 0; b < mouse_button_count && !leave; b++)
        {
          /* Only leave if user both pressed and released the mouse, and in
             that order.  This avoids popping down the menu pane unless
             the user is really done with it.  */
          if (mouse_pressed (b, &x, &y))
            {
              while (mouse_button_depressed (b, &x, &y))
                __dpmi_yield ();
              leave = 1;
            }
          (void) mouse_released (b, &x, &y);
        }
    }

  mouse_off ();
  ScreenUpdate (state[0].screen_behind);
  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (0, screen_size);
  while (statecount--)
    xfree (state[statecount].screen_behind);
  IT_display_cursor (1);        /* turn cursor back on */
  /* Clean up any mouse events that are waiting inside Emacs event queue.
     These events are likely to be generated before the menu was even
     displayed, probably because the user pressed and released the button
     (which invoked the menu) too quickly.  If we don't remove these events,
     Emacs will process them after we return and surprise the user.  */
  discard_mouse_events ();
  /* Allow mouse events generation by dos_rawgetc.  */
  mouse_preempted--;
  return result;
}

/* Dispose of a menu.  */

void
XMenuDestroy (Display *foo, XMenu *menu)
{
  int i;
  if (menu->allocated)
    {
      for (i = 0; i < menu->count; i++)
        if (menu->submenu[i])
          XMenuDestroy (foo, menu->submenu[i]);
      xfree (menu->text);
      xfree (menu->submenu);
      xfree (menu->panenumber);
    }
  xfree (menu);
}

int
x_pixel_width (struct frame *f)
{
  return FRAME_WIDTH (f);
}

int
x_pixel_height (struct frame *f)
{
  return FRAME_HEIGHT (f);
}
#endif /* !HAVE_X_WINDOWS */
\f
/* ----------------------- DOS / UNIX conversion --------------------- */

void msdos_downcase_filename (unsigned char *);

/* Destructively turn backslashes into slashes.  */

void
dostounix_filename (p)
     register char *p;
{
  msdos_downcase_filename (p);

  while (*p)
    {
      if (*p == '\\')
        *p = '/';
      p++;
    }
}

/* Destructively turn slashes into backslashes.  */

void
unixtodos_filename (p)
     register char *p;
{
  if (p[1] == ':' && *p >= 'A' && *p <= 'Z')
    {
      *p += 'a' - 'A';
      p += 2;
    }

  while (*p)
    {
      if (*p == '/')
        *p = '\\';
      p++;
    }
}

/* Get the default directory for a given drive.  0=def, 1=A, 2=B, ...  */

int
getdefdir (drive, dst)
     int drive;
     char *dst;
{
  char in_path[4], *p = in_path;
  int e = errno;

  /* Generate "X:." (when drive is X) or "." (when drive is 0).  */
  if (drive != 0)
    {
      *p++ = drive + 'A' - 1;
      *p++ = ':';
    }

  *p++ = '.';
  *p = '\0';
  errno = 0;
  _fixpath (in_path, dst);
    /* _fixpath can set errno to ENOSYS on non-LFN systems because
       it queries the LFN support, so ignore that error.  */
  if ((errno && errno != ENOSYS) || *dst == '\0')
    return 0;

  msdos_downcase_filename (dst);

  errno = e;
  return 1;
}

/* Remove all CR's that are followed by a LF.  */

int
crlf_to_lf (n, buf)
     register int n;
     register unsigned char *buf;
{
  unsigned char *np = buf;
  unsigned char *startp = buf;
  unsigned char *endp = buf + n;

  if (n == 0)
    return n;
  while (buf < endp - 1)
    {
      if (*buf == 0x0d)
        {
          if (*(++buf) != 0x0a)
            *np++ = 0x0d;
        }
      else
        *np++ = *buf++;
    }
  if (buf < endp)
    *np++ = *buf++;
  return np - startp;
}

#if defined(__DJGPP__) && __DJGPP__ == 2 && __DJGPP_MINOR__ == 0

/* In DJGPP v2.0, library `write' can call `malloc', which might
   cause relocation of the buffer whose address we get in ADDR.
   Here is a version of `write' that avoids calling `malloc',
   to serve us until such time as the library is fixed.
   Actually, what we define here is called `__write', because
   `write' is a stub that just jmp's to `__write' (to be
   POSIXLY-correct with respect to the global name-space).  */

#include <io.h>               /* for _write */
#include <libc/dosio.h>       /* for __file_handle_modes[] */

static char xbuf[64 * 1024];  /* DOS cannot write more in one chunk */

#define XBUF_END (xbuf + sizeof (xbuf) - 1)

int
__write (int handle, const void *buffer, size_t count)
{
  if (count == 0)
    return 0;

  if(__file_handle_modes[handle] & O_BINARY)
    return _write (handle, buffer, count);
  else
    {
      char *xbp = xbuf;
      const char *bp = buffer;
      int total_written = 0;
      int nmoved = 0, ncr = 0;

      while (count)
        {
          /* The next test makes sure there's space for at least 2 more
             characters in xbuf[], so both CR and LF can be put there.  */
          if (xbp < XBUF_END)
            {
              if (*bp == '\n')
                {
                  ncr++;
                  *xbp++ = '\r';
                }
              *xbp++ = *bp++;
              nmoved++;
              count--;
            }
          if (xbp >= XBUF_END || !count)
            {
              size_t to_write = nmoved + ncr;
              int written = _write (handle, xbuf, to_write);

              if (written == -1)
                return -1;
              else
                total_written += nmoved;  /* CRs aren't counted in ret value */

              /* If some, but not all were written (disk full?), return
                 an estimate of the total written bytes not counting CRs.  */
              if (written < to_write)
                return total_written - (to_write - written) * nmoved/to_write;

              nmoved = 0;
              ncr = 0;
              xbp = xbuf;
            }
        }
      return total_written;
    }
}

/* A low-level file-renaming function which works around Windows 95 bug.
   This is pulled directly out of DJGPP v2.01 library sources, and only
   used when you compile with DJGPP v2.0.  */

#include <io.h>
 
int _rename(const char *old, const char *new)
{
  __dpmi_regs r;
  int olen    = strlen(old) + 1;
  int i;
  int use_lfn = _USE_LFN;
  char tempfile[FILENAME_MAX];
  const char *orig = old;
  int lfn_fd = -1;

  r.x.dx = __tb_offset;
  r.x.di = __tb_offset + olen;
  r.x.ds = r.x.es = __tb_segment;

  if (use_lfn)
    {
      /* Windows 95 bug: for some filenames, when you rename
         file -> file~ (as in Emacs, to leave a backup), the
         short 8+3 alias doesn't change, which effectively
         makes OLD and NEW the same file.  We must rename
         through a temporary file to work around this.  */

      char *pbase = 0, *p;
      static char try_char[] = "abcdefghijklmnopqrstuvwxyz012345789";
      int idx = sizeof(try_char) - 1;

      /* Generate a temporary name.  Can't use `tmpnam', since $TMPDIR
         might point to another drive, which will fail the DOS call.  */
      strcpy(tempfile, old);
      for (p = tempfile; *p; p++) /* ensure temporary is on the same drive */
        if (*p == '/' || *p == '\\' || *p == ':')
          pbase = p;
      if (pbase)
        pbase++;
      else
        pbase = tempfile;
      strcpy(pbase, "X$$djren$$.$$temp$$");

      do
        {
          if (idx <= 0)
            return -1;
          *pbase = try_char[--idx];
        } while (_chmod(tempfile, 0) != -1);

      r.x.ax = 0x7156;
      _put_path2(tempfile, olen);
      _put_path(old);
      __dpmi_int(0x21, &r);
      if (r.x.flags & 1)
        {
          errno = __doserr_to_errno(r.x.ax);
          return -1;
        }

      /* Now create a file with the original name.  This will
         ensure that NEW will always have a 8+3 alias
         different from that of OLD.  (Seems to be required
         when NameNumericTail in the Registry is set to 0.)  */
      lfn_fd = _creat(old, 0);

      olen = strlen(tempfile) + 1;
      old  = tempfile;
      r.x.di = __tb_offset + olen;
    }

  for (i=0; i<2; i++)
    {
      if(use_lfn)
        r.x.ax = 0x7156;
      else
        r.h.ah = 0x56;
      _put_path2(new, olen);
      _put_path(old);
      __dpmi_int(0x21, &r);
      if(r.x.flags & 1)
        {
          if (r.x.ax == 5 && i == 0) /* access denied */
            remove(new);                 /* and try again */
          else
            {
              errno = __doserr_to_errno(r.x.ax);

              /* Restore to original name if we renamed it to temporary.  */
              if (use_lfn)
                {
                  if (lfn_fd != -1)
                    {
                      _close (lfn_fd);
                      remove (orig);
                    }
                  _put_path2(orig, olen);
                  _put_path(tempfile);
                  r.x.ax = 0x7156;
                  __dpmi_int(0x21, &r);
                }
              return -1;
            }
        }
      else
        break;
    }

  /* Success.  Delete the file possibly created to work
     around the Windows 95 bug.  */
  if (lfn_fd != -1)
    return (_close (lfn_fd) == 0) ? remove (orig) : -1;
  return 0;
}

#endif /* __DJGPP__ == 2 && __DJGPP_MINOR__ == 0 */

DEFUN ("msdos-long-file-names", Fmsdos_long_file_names, Smsdos_long_file_names,
  0, 0, 0,
  "Return non-nil if long file names are supported on MSDOS.")
  ()
{
  return (_USE_LFN ? Qt : Qnil);
}

/* Convert alphabetic characters in a filename to lower-case.  */

void
msdos_downcase_filename (p)
     register unsigned char *p;
{
  /* Always lower-case drive letters a-z, even if the filesystem
     preserves case in filenames.
     This is so MSDOS filenames could be compared by string comparison
     functions that are case-sensitive.  Even case-preserving filesystems
     do not distinguish case in drive letters.  */
  if (p[1] == ':' && *p >= 'A' && *p <= 'Z')
    {
      *p += 'a' - 'A';
      p += 2;
    }

  /* Under LFN we expect to get pathnames in their true case.  */
  if (NILP (Fmsdos_long_file_names ()))
    for ( ; *p; p++)
      if (*p >= 'A' && *p <= 'Z')
        *p += 'a' - 'A';
}

DEFUN ("msdos-downcase-filename", Fmsdos_downcase_filename, Smsdos_downcase_filename,
       1, 1, 0,
  "Convert alphabetic characters in FILENAME to lower case and return that.\n\
When long filenames are supported, doesn't change FILENAME.\n\
If FILENAME is not a string, returns nil.\n\
The argument object is never altered--the value is a copy.")
  (filename)
     Lisp_Object filename;
{
  Lisp_Object tem;

  if (! STRINGP (filename))
    return Qnil;

  tem = Fcopy_sequence (filename);
  msdos_downcase_filename (XSTRING (tem)->data);
  return tem;
}
\f
/* The Emacs root directory as determined by init_environment.  */

static char emacsroot[MAXPATHLEN];

char *
rootrelativepath (rel)
     char *rel;
{
  static char result[MAXPATHLEN + 10];

  strcpy (result, emacsroot);
  strcat (result, "/");
  strcat (result, rel);
  return result;
}

/* Define a lot of environment variables if not already defined.  Don't
   remove anything unless you know what you're doing -- lots of code will
   break if one or more of these are missing.  */

void
init_environment (argc, argv, skip_args)
     int argc;
     char **argv;
     int skip_args;
{
  char *s, *t, *root;
  int len;
  static const char * const tempdirs[] = {
    "$TMPDIR", "$TEMP", "$TMP", "c:/"
  };
  int i;
  const int imax = sizeof (tempdirs) / sizeof (tempdirs[0]);

  /* Make sure they have a usable $TMPDIR.  Many Emacs functions use
     temporary files and assume "/tmp" if $TMPDIR is unset, which
     will break on DOS/Windows.  Refuse to work if we cannot find
     a directory, not even "c:/", usable for that purpose.  */
  for (i = 0; i < imax ; i++)
    {
      const char *tmp = tempdirs[i];

      if (*tmp == '$')
        tmp = getenv (tmp + 1);
      /* Note that `access' can lie to us if the directory resides on a
         read-only filesystem, like CD-ROM or a write-protected floppy.
         The only way to be really sure is to actually create a file and
         see if it succeeds.  But I think that's too much to ask.  */
      if (tmp && access (tmp, D_OK) == 0)
        {
          setenv ("TMPDIR", tmp, 1);
          break;
        }
    }
  if (i >= imax)
    cmd_error_internal
      (Fcons (Qerror,
              Fcons (build_string ("no usable temporary directories found!!"),
                     Qnil)),
       "While setting TMPDIR: ");

  /* Note the startup time, so we know not to clear the screen if we
     exit immediately; see IT_reset_terminal_modes.
     (Yes, I know `clock' returns zero the first time it's called, but
     I do this anyway, in case some wiseguy changes that at some point.)  */
  startup_time = clock ();

  /* Find our root from argv[0].  Assuming argv[0] is, say,
     "c:/emacs/bin/emacs.exe" our root will be "c:/emacs".  */
  root = alloca (MAXPATHLEN + 20);
  _fixpath (argv[0], root);
  msdos_downcase_filename (root);
  len = strlen (root);
  while (len > 0 && root[len] != '/' && root[len] != ':')
    len--;
  root[len] = '\0';
  if (len > 4
      && (strcmp (root + len - 4, "/bin") == 0
          || strcmp (root + len - 4, "/src") == 0)) /* under a debugger */
    root[len - 4] = '\0';
  else
    strcpy (root, "c:/emacs");  /* let's be defensive */
  len = strlen (root);
  strcpy (emacsroot, root);

  /* We default HOME to our root.  */
  setenv ("HOME", root, 0);

  /* We default EMACSPATH to root + "/bin".  */
  strcpy (root + len, "/bin");
  setenv ("EMACSPATH", root, 0);

  /* I don't expect anybody to ever use other terminals so the internal
     terminal is the default.  */
  setenv ("TERM", "internal", 0);

#ifdef HAVE_X_WINDOWS
  /* Emacs expects DISPLAY to be set.  */
  setenv ("DISPLAY", "unix:0.0", 0);
#endif

  /* SHELL is a bit tricky -- COMSPEC is the closest we come, but we must
     downcase it and mirror the backslashes.  */
  s = getenv ("COMSPEC");
  if (!s) s = "c:/command.com";
  t = alloca (strlen (s) + 1);
  strcpy (t, s);
  dostounix_filename (t);
  setenv ("SHELL", t, 0);

  /* PATH is also downcased and backslashes mirrored.  */
  s = getenv ("PATH");
  if (!s) s = "";
  t = alloca (strlen (s) + 3);
  /* Current directory is always considered part of MsDos's path but it is
     not normally mentioned.  Now it is.  */
  strcat (strcpy (t, ".;"), s);
  dostounix_filename (t); /* Not a single file name, but this should work.  */
  setenv ("PATH", t, 1);

  /* In some sense all dos users have root privileges, so...  */
  setenv ("USER", "root", 0);
  setenv ("NAME", getenv ("USER"), 0);

  /* Time zone determined from country code.  To make this possible, the
     country code may not span more than one time zone.  In other words,
     in the USA, you lose.  */
  if (!getenv ("TZ"))
    switch (dos_country_code)
      {
      case 31:                  /* Belgium */
      case 32:                  /* The Netherlands */
      case 33:                  /* France */
      case 34:                  /* Spain */
      case 36:                  /* Hungary */
      case 38:                  /* Yugoslavia (or what's left of it?) */
      case 39:                  /* Italy */
      case 41:                  /* Switzerland */
      case 42:                  /* Tjekia */
      case 45:                  /* Denmark */
      case 46:                  /* Sweden */
      case 47:                  /* Norway */
      case 48:                  /* Poland */
      case 49:                  /* Germany */
        /* Daylight saving from last Sunday in March to last Sunday in
           September, both at 2AM.  */
        setenv ("TZ", "MET-01METDST-02,M3.5.0/02:00,M9.5.0/02:00", 0);
        break;
      case 44:                  /* United Kingdom */
      case 351:                 /* Portugal */
      case 354:                 /* Iceland */
        setenv ("TZ", "GMT+00", 0);
        break;
      case 81:                  /* Japan */
      case 82:                  /* Korea */
        setenv ("TZ", "JST-09", 0);
        break;
      case 90:                  /* Turkey */
      case 358:                 /* Finland */
        setenv ("TZ", "EET-02", 0);
        break;
      case 972:                 /* Israel */
        /* This is an approximation.  (For exact rules, use the
           `zoneinfo/israel' file which comes with DJGPP, but you need
           to install it in `/usr/share/zoneinfo/' directory first.)  */
        setenv ("TZ", "IST-02IDT-03,M4.1.6/00:00,M9.5.6/01:00", 0);
        break;
      }
  tzset ();
}

\f

static int break_stat;   /* BREAK check mode status.    */
static int stdin_stat;   /* stdin IOCTL status.         */

#if __DJGPP__ < 2

/* These must be global.  */
static _go32_dpmi_seginfo ctrl_break_vector;
static _go32_dpmi_registers ctrl_break_regs;
static int ctrlbreakinstalled = 0;

/* Interrupt level detection of Ctrl-Break.  Don't do anything fancy here!  */

void
ctrl_break_func (regs)
     _go32_dpmi_registers *regs;
{
  Vquit_flag = Qt;
}

void
install_ctrl_break_check ()
{
  if (!ctrlbreakinstalled)
    {
      /* Don't press Ctrl-Break if you don't have either DPMI or Emacs
         was compiler with Djgpp 1.11 maintenance level 5 or later!  */
      ctrlbreakinstalled = 1;
      ctrl_break_vector.pm_offset = (int) ctrl_break_func;
      _go32_dpmi_allocate_real_mode_callback_iret (&ctrl_break_vector,
                                                   &ctrl_break_regs);
      _go32_dpmi_set_real_mode_interrupt_vector (0x1b, &ctrl_break_vector);
    }
}

#endif /* __DJGPP__ < 2 */

/* Turn off Dos' Ctrl-C checking and inhibit interpretation of
   control chars by DOS.   Determine the keyboard type.  */

int
dos_ttraw ()
{
  union REGS inregs, outregs;
  static int first_time = 1;
  
  break_stat = getcbrk ();
  setcbrk (0);
#if __DJGPP__ < 2
  install_ctrl_break_check ();
#endif

  if (first_time)
    {
      inregs.h.ah = 0xc0;
      int86 (0x15, &inregs, &outregs);
      extended_kbd = (!outregs.x.cflag) && (outregs.h.ah == 0);
  
      have_mouse = 0;

      if (internal_terminal
#ifdef HAVE_X_WINDOWS
          && inhibit_window_system
#endif
          )
        {
          inregs.x.ax = 0x0021;
          int86 (0x33, &inregs, &outregs);
          have_mouse = (outregs.x.ax & 0xffff) == 0xffff;
          if (!have_mouse)
            {
              /* Reportedly, the above doesn't work for some mouse drivers.  There
                 is an additional detection method that should work, but might be
                 a little slower.  Use that as an alternative.  */
              inregs.x.ax = 0x0000;
              int86 (0x33, &inregs, &outregs);
              have_mouse = (outregs.x.ax & 0xffff) == 0xffff;
            }

          if (have_mouse)
            {
              have_mouse = 1;   /* enable mouse */
              mouse_visible = 0;
              
              if (outregs.x.bx == 3)
                {
                  mouse_button_count = 3;
                  mouse_button_translate[0] = 0; /* Left */
                  mouse_button_translate[1] = 2; /* Middle */
                  mouse_button_translate[2] = 1; /* Right */
                }
              else
                {
                  mouse_button_count = 2;
                  mouse_button_translate[0] = 0;
                  mouse_button_translate[1] = 1;
                }
              mouse_position_hook = &mouse_get_pos;
              mouse_init ();
            }
        }

      first_time = 0;

#if __DJGPP__ >= 2

      stdin_stat = setmode (fileno (stdin), O_BINARY);
      return (stdin_stat != -1);
    }
  else
    return (setmode (fileno (stdin), O_BINARY) != -1);

#else /* __DJGPP__ < 2 */

    }

  /* I think it is wrong to overwrite `stdin_stat' every time
     but the first one this function is called, but I don't
     want to change the way it used to work in v1.x.--EZ  */

  inregs.x.ax = 0x4400;         /* Get IOCTL status. */
  inregs.x.bx = 0x00;           /* 0 = stdin. */
  intdos (&inregs, &outregs);
  stdin_stat = outregs.h.dl;

  inregs.x.dx = stdin_stat | 0x0020; /* raw mode */
  inregs.x.ax = 0x4401;         /* Set IOCTL status */
  intdos (&inregs, &outregs);
  return !outregs.x.cflag;

#endif /* __DJGPP__ < 2 */
}

/*  Restore status of standard input and Ctrl-C checking.  */

int
dos_ttcooked ()
{
  union REGS inregs, outregs;

  setcbrk (break_stat);
  mouse_off ();

#if __DJGPP__ >= 2

  return (setmode (fileno (stdin), stdin_stat) != -1);

#else  /* not __DJGPP__ >= 2 */

  inregs.x.ax = 0x4401; /* Set IOCTL status.    */
  inregs.x.bx = 0x00;   /* 0 = stdin.           */
  inregs.x.dx = stdin_stat;
  intdos (&inregs, &outregs);
  return !outregs.x.cflag;

#endif /* not __DJGPP__ >= 2 */
}

\f
/* Run command as specified by ARGV in directory DIR.
   The command is run with input from TEMPIN, output to
   file TEMPOUT and stderr to TEMPERR.  */

int
run_msdos_command (argv, working_dir, tempin, tempout, temperr, envv)
     unsigned char **argv;
     const char *working_dir;
     int tempin, tempout, temperr;
     char **envv;
{
  char *saveargv1, *saveargv2, *lowcase_argv0, *pa, *pl;
  char oldwd[MAXPATHLEN + 1]; /* Fixed size is safe on MSDOS.  */
  int msshell, result = -1;
  int inbak, outbak, errbak;
  int x, y;
  Lisp_Object cmd;

  /* Get current directory as MSDOS cwd is not per-process.  */
  getwd (oldwd);

  /* If argv[0] is the shell, it might come in any lettercase.
     Since `Fmember' is case-sensitive, we need to downcase
     argv[0], even if we are on case-preserving filesystems.  */
  lowcase_argv0 = alloca (strlen (argv[0]) + 1);
  for (pa = argv[0], pl = lowcase_argv0; *pa; pl++)
    {
      *pl = *pa++;
      if (*pl >= 'A' && *pl <= 'Z')
        *pl += 'a' - 'A';
    }
  *pl = '\0';

  cmd = Ffile_name_nondirectory (build_string (lowcase_argv0));
  msshell = !NILP (Fmember (cmd, Fsymbol_value (intern ("msdos-shells"))))
    && !strcmp ("-c", argv[1]);
  if (msshell)
    {
      saveargv1 = argv[1];
      saveargv2 = argv[2];
      argv[1] = "/c";
      if (argv[2])
        {
          char *p = alloca (strlen (argv[2]) + 1);

          strcpy (argv[2] = p, saveargv2);
          while (*p && isspace (*p))
            p++;
          while (*p && !isspace (*p))
            if (*p == '/')
              *p++ = '\\';
            else
              p++;
        }
    }

  chdir (working_dir);
  inbak = dup (0);
  outbak = dup (1);
  errbak = dup (2);
  if (inbak < 0 || outbak < 0 || errbak < 0)
    goto done; /* Allocation might fail due to lack of descriptors.  */

  if (have_mouse > 0)
    mouse_get_xy (&x, &y);

  dos_ttcooked ();      /* do it here while 0 = stdin */
  
  dup2 (tempin, 0);
  dup2 (tempout, 1);
  dup2 (temperr, 2);

#if __DJGPP__ > 1

  if (msshell && !argv[3])
    {
      /* MS-DOS native shells are too restrictive.  For starters, they
         cannot grok commands longer than 126 characters.  In DJGPP v2
         and later, `system' is much smarter, so we'll call it instead.  */

      const char *cmnd;

      /* A shell gets a single argument--its full command
         line--whose original was saved in `saveargv2'.  */

      /* Don't let them pass empty command lines to `system', since
         with some shells it will try to invoke an interactive shell,
         which will hang Emacs.  */
      for (cmnd = saveargv2; *cmnd && isspace (*cmnd); cmnd++)
        ;
      if (*cmnd)
        {
          extern char **environ;
          int save_system_flags = __system_flags;

          /* Request the most powerful version of `system'.  We need
             all the help we can get to avoid calling stock DOS shells.  */
          __system_flags =  (__system_redirect
                             | __system_use_shell
                             | __system_allow_multiple_cmds
                             | __system_allow_long_cmds
                             | __system_handle_null_commands
                             | __system_emulate_chdir);

          environ = envv;
          result = system (cmnd);
          __system_flags = save_system_flags;
        }
      else
        result = 0;     /* emulate Unixy shell behavior with empty cmd line */
    }
  else

#endif /* __DJGPP__ > 1 */

  result = spawnve (P_WAIT, argv[0], argv, envv);
  
  dup2 (inbak, 0);
  dup2 (outbak, 1);
  dup2 (errbak, 2);
  emacs_close (inbak);
  emacs_close (outbak);
  emacs_close (errbak);

  dos_ttraw ();
  if (have_mouse > 0)
    {
      mouse_init ();
      mouse_moveto (x, y);
    }

  /* Some programs might change the meaning of the highest bit of the
     text attribute byte, so we get blinking characters instead of the
     bright background colors.  Restore that.  */
  bright_bg ();
  
 done:
  chdir (oldwd);
  if (msshell)
    {
      argv[1] = saveargv1;
      argv[2] = saveargv2;
    }
  return result;
}

croak (badfunc)
     char *badfunc;
{
  fprintf (stderr, "%s not yet implemented\r\n", badfunc);
  reset_sys_modes ();
  exit (1);
}
\f
#if __DJGPP__ < 2

/* ------------------------- Compatibility functions -------------------
 *      gethostname
 *      gettimeofday
 */

/* Hostnames for a pc are not really funny,
   but they are used in change log so we emulate the best we can.  */

gethostname (p, size)
     char *p;
     int size;
{
  char *q = egetenv ("HOSTNAME");

  if (!q) q = "pc";
  strcpy (p, q);
  return 0;
}

/* When time zones are set from Ms-Dos too many C-libraries are playing
   tricks with time values.  We solve this by defining our own version
   of `gettimeofday' bypassing GO32.  Our version needs to be initialized
   once and after each call to `tzset' with TZ changed.  That is 
   accomplished by aliasing tzset to init_gettimeofday. */

static struct tm time_rec;

int
gettimeofday (struct timeval *tp, struct timezone *tzp)
{
  if (tp)
    {
      struct time t;
      struct tm tm;
      
      gettime (&t);
      if (t.ti_hour < time_rec.tm_hour) /* midnight wrap */
        {
          struct date d;
          getdate (&d);
          time_rec.tm_year = d.da_year - 1900;
          time_rec.tm_mon = d.da_mon - 1;
          time_rec.tm_mday = d.da_day;
        }
      
      time_rec.tm_hour = t.ti_hour;
      time_rec.tm_min = t.ti_min;
      time_rec.tm_sec = t.ti_sec;

      tm = time_rec;
      tm.tm_gmtoff = dos_timezone_offset;
      
      tp->tv_sec = mktime (&tm);        /* may modify tm */
      tp->tv_usec = t.ti_hund * (1000000 / 100);
    }
  /* Ignore tzp; it's obsolescent.  */
  return 0;
}

#endif /* __DJGPP__ < 2 */

/*
 * A list of unimplemented functions that we silently ignore.
 */

#if __DJGPP__ < 2
unsigned alarm (s) unsigned s; {}
fork () { return 0; }
int kill (x, y) int x, y; { return -1; }
nice (p) int p; {}
void volatile pause () {}
sigsetmask (x) int x; { return 0; }
sigblock (mask) int mask; { return 0; } 
#endif

void request_sigio (void) {}
setpgrp () {return 0; }
setpriority (x,y,z) int x,y,z; { return 0; }
void unrequest_sigio (void) {}

#if __DJGPP__ > 1

#ifdef POSIX_SIGNALS

/* Augment DJGPP library POSIX signal functions.  This is needed
   as of DJGPP v2.01, but might be in the library in later releases. */

#include <libc/bss.h>

/* A counter to know when to re-initialize the static sets.  */
static int sigprocmask_count = -1;

/* Which signals are currently blocked (initially none).  */
static sigset_t current_mask;

/* Which signals are pending (initially none).  */
static sigset_t pending_signals;

/* Previous handlers to restore when the blocked signals are unblocked.  */
typedef void (*sighandler_t)(int);
static sighandler_t prev_handlers[320];

/* A signal handler which just records that a signal occured
   (it will be raised later, if and when the signal is unblocked).  */
static void
sig_suspender (signo)
     int signo;
{
  sigaddset (&pending_signals, signo);
}

int
sigprocmask (how, new_set, old_set)
     int how;
     const sigset_t *new_set;
     sigset_t *old_set;
{
  int signo;
  sigset_t new_mask;

  /* If called for the first time, initialize.  */
  if (sigprocmask_count != __bss_count)
    {
      sigprocmask_count = __bss_count;
      sigemptyset (&pending_signals);
      sigemptyset (&current_mask);
      for (signo = 0; signo < 320; signo++)
        prev_handlers[signo] = SIG_ERR;
    }

  if (old_set)
    *old_set = current_mask;

  if (new_set == 0)
    return 0;

  if (how != SIG_BLOCK && how != SIG_UNBLOCK && how != SIG_SETMASK)
    {
      errno = EINVAL;
      return -1;
    }

  sigemptyset (&new_mask);

  /* DJGPP supports upto 320 signals.  */
  for (signo = 0; signo < 320; signo++)
    {
      if (sigismember (&current_mask, signo))
        sigaddset (&new_mask, signo);
      else if (sigismember (new_set, signo) && how != SIG_UNBLOCK)
        {
          sigaddset (&new_mask, signo);

          /* SIGKILL is silently ignored, as on other platforms.  */
          if (signo != SIGKILL && prev_handlers[signo] == SIG_ERR)
            prev_handlers[signo] = signal (signo, sig_suspender);
        }
      if ((   how == SIG_UNBLOCK
              && sigismember (&new_mask, signo)
              && sigismember (new_set, signo))
          || (how == SIG_SETMASK
              && sigismember (&new_mask, signo)
              && !sigismember (new_set, signo)))
        {
          sigdelset (&new_mask, signo);
          if (prev_handlers[signo] != SIG_ERR)
            {
              signal (signo, prev_handlers[signo]);
              prev_handlers[signo] = SIG_ERR;
            }
          if (sigismember (&pending_signals, signo))
            {
              sigdelset (&pending_signals, signo);
              raise (signo);
            }
        }
    }
  current_mask = new_mask;
  return 0;
}

#else /* not POSIX_SIGNALS */

sigsetmask (x) int x; { return 0; }
sigblock (mask) int mask; { return 0; } 

#endif /* not POSIX_SIGNALS */
#endif /* __DJGPP__ > 1 */

#ifndef HAVE_SELECT
#include "sysselect.h"

#ifndef EMACS_TIME_ZERO_OR_NEG_P
#define EMACS_TIME_ZERO_OR_NEG_P(time)  \
  ((long)(time).tv_sec < 0              \
   || ((time).tv_sec == 0               \
       && (long)(time).tv_usec <= 0))
#endif

/* This yields the rest of the current time slice to the task manager.
   It should be called by any code which knows that it has nothing
   useful to do except idle.

   I don't use __dpmi_yield here, since versions of library before 2.02
   called Int 2Fh/AX=1680h there in a way that would wedge the DOS box
   on some versions of Windows 9X.  */

void
dos_yield_time_slice (void)
{
  _go32_dpmi_registers r;

  r.x.ax = 0x1680;
  r.x.ss = r.x.sp = r.x.flags = 0;
  _go32_dpmi_simulate_int (0x2f, &r);
  if (r.h.al == 0x80)
    errno = ENOSYS;
}

/* Only event queue is checked.  */
/* We don't have to call timer_check here
   because wait_reading_process_input takes care of that.  */
int
sys_select (nfds, rfds, wfds, efds, timeout)
     int nfds;
     SELECT_TYPE *rfds, *wfds, *efds;
     EMACS_TIME *timeout;
{
  int check_input;
  struct time t;

  check_input = 0;
  if (rfds)
    {
      check_input = FD_ISSET (0, rfds);
      FD_ZERO (rfds);
    }
  if (wfds)
    FD_ZERO (wfds);
  if (efds)
    FD_ZERO (efds);

  if (nfds != 1)
    abort ();
  
  /* If we are looking only for the terminal, with no timeout,
     just read it and wait -- that's more efficient.  */
  if (!timeout)
    {
      while (!detect_input_pending ())
        {
          dos_yield_time_slice ();
        }
    }
  else
    {
      EMACS_TIME clnow, cllast, cldiff;

      gettime (&t);
      EMACS_SET_SECS_USECS (cllast, t.ti_sec, t.ti_hund * 10000L);

      while (!check_input || !detect_input_pending ())
        {
          gettime (&t);
          EMACS_SET_SECS_USECS (clnow, t.ti_sec, t.ti_hund * 10000L);
          EMACS_SUB_TIME (cldiff, clnow, cllast);

          /* When seconds wrap around, we assume that no more than
             1 minute passed since last `gettime'.  */
          if (EMACS_TIME_NEG_P (cldiff))
            EMACS_SET_SECS (cldiff, EMACS_SECS (cldiff) + 60);
          EMACS_SUB_TIME (*timeout, *timeout, cldiff);

          /* Stop when timeout value crosses zero.  */
          if (EMACS_TIME_ZERO_OR_NEG_P (*timeout))
            return 0;
          cllast = clnow;
          dos_yield_time_slice ();
        }
    }
  
  FD_SET (0, rfds);
  return 1;
}
#endif

/*
 * Define overlaid functions:
 *
 *      chdir -> sys_chdir
 *      tzset -> init_gettimeofday
 *      abort -> dos_abort
 */

#ifdef chdir
#undef chdir
extern int chdir ();

int
sys_chdir (path)
     const char* path;
{
  int len = strlen (path);
  char *tmp = (char *)path;

  if (*tmp && tmp[1] == ':')
    {
      if (getdisk () != tolower (tmp[0]) - 'a')
        setdisk (tolower (tmp[0]) - 'a');
      tmp += 2; /* strip drive: KFS 1995-07-06 */
      len -= 2;
    }
  
  if (len > 1 && (tmp[len - 1] == '/'))
    {
      char *tmp1 = (char *) alloca (len + 1);
      strcpy (tmp1, tmp);
      tmp1[len - 1] = 0;
      tmp = tmp1;
    }
  return chdir (tmp);
}
#endif

#ifdef tzset
#undef tzset
extern void tzset (void);

void
init_gettimeofday ()
{
  time_t ltm, gtm;
  struct tm *lstm;

  tzset ();
  ltm = gtm = time (NULL);
  ltm = mktime (lstm = localtime (&ltm));
  gtm = mktime (gmtime (&gtm));
  time_rec.tm_hour = 99;        /* force gettimeofday to get date */
  time_rec.tm_isdst = lstm->tm_isdst;
  dos_timezone_offset = time_rec.tm_gmtoff = (int)(gtm - ltm) / 60;
}
#endif

#ifdef abort
#undef abort
void
dos_abort (file, line)
     char *file;
     int  line;
{
  char buffer1[200], buffer2[400];
  int i, j;
  
  sprintf (buffer1, "<EMACS FATAL ERROR IN %s LINE %d>", file, line);
  for (i = j = 0; buffer1[i]; i++) {
    buffer2[j++] = buffer1[i];
    buffer2[j++] = 0x70;
  }
  dosmemput (buffer2, j, (int)ScreenPrimary);
  ScreenSetCursor (2, 0);
  abort ();
}
#else
void
abort ()
{
  dos_ttcooked ();
  ScreenSetCursor (10, 0);
  cputs ("\r\n\nEmacs aborted!\r\n");
#if __DJGPP__ > 1
#if __DJGPP__ == 2 && __DJGPP_MINOR__ < 2
  if (screen_virtual_segment)
    dosv_refresh_virtual_screen (2 * 10 * screen_size_X, 4 * screen_size_X);
  /* Generate traceback, so we could tell whodunit.  */
  signal (SIGINT, SIG_DFL);
  __asm__ __volatile__ ("movb $0x1b,%al;call ___djgpp_hw_exception");
#else  /* __DJGPP_MINOR__ >= 2 */
  raise (SIGABRT);
#endif /* __DJGPP_MINOR__ >= 2 */
#endif
  exit (2);
}
#endif

/* The following variables are required so that cus-start.el won't
   complain about unbound variables.  */
#ifndef HAVE_X_WINDOWS
/* Search path for bitmap files (xfns.c).  */
Lisp_Object Vx_bitmap_file_path;
int x_stretch_cursor_p;
#endif
#ifndef subprocesses
/* Nonzero means delete a process right away if it exits (process.c).  */
static int delete_exited_processes;
#endif

syms_of_msdos ()
{
  recent_doskeys = Fmake_vector (make_number (NUM_RECENT_DOSKEYS), Qnil);
  staticpro (&recent_doskeys);
#ifndef HAVE_X_WINDOWS
  DEFVAR_LISP ("x-bitmap-file-path", &Vx_bitmap_file_path,
    "List of directories to search for bitmap files for X.");
  Vx_bitmap_file_path = decode_env_path ((char *) 0, ".");

  DEFVAR_BOOL ("x-stretch-cursor", &x_stretch_cursor_p,
    "*Non-nil means draw block cursor as wide as the glyph under it.\n\
For example, if a block cursor is over a tab, it will be drawn as\n\
wide as that tab on the display.  (No effect on MS-DOS.)");
  x_stretch_cursor_p = 0;

  /* The following three are from xfns.c:  */
  Qbackground_color = intern ("background-color");
  staticpro (&Qbackground_color);
  Qforeground_color = intern ("foreground-color");
  staticpro (&Qforeground_color);

  DEFVAR_LISP ("dos-unsupported-char-glyph", &Vdos_unsupported_char_glyph,
   "*Glyph to display instead of chars not supported by current codepage.\n\

This variable is used only by MSDOS terminals.");
    Vdos_unsupported_char_glyph = '\177';
#endif
#ifndef subprocesses
  DEFVAR_BOOL ("delete-exited-processes", &delete_exited_processes,
    "*Non-nil means delete processes immediately when they exit.\n\
nil means don't delete them until `list-processes' is run.");
  delete_exited_processes = 0;
#endif

  defsubr (&Srecent_doskeys);
  defsubr (&Smsdos_long_file_names);
  defsubr (&Smsdos_downcase_filename);
  defsubr (&Smsdos_remember_default_colors);
}

#endif /* MSDOS */