static void
end_callbacks (void)
{
  if (callbacks_initialized)
    {
      gdb_callback.shutdown (&gdb_callback);
      callbacks_initialized = 0;
    }
}

int
create_inferior (char *program, char **argv)
{
  bfd *abfd;
  int pid = 0;
  char **new_argv;
  int nargs;

  abfd = bfd_openr (program, 0);
  if (!abfd)
    {
      fprintf (stderr, "gdbserver: cannot open %s: %s\n",
	       program, bfd_errmsg (bfd_get_error ()));
      exit (1);
    }

  if (!bfd_check_format (abfd, bfd_object))
    {
      fprintf (stderr, "gdbserver: unknown load format for %s: %s\n",
	       program, bfd_errmsg (bfd_get_error ()));
      exit (1);
    }

  /* Add "-E big" or "-E little" to the argument list depending on the
     endianness of the program to be loaded.  */
  for (nargs = 0; argv[nargs] != NULL; nargs++)		/* count the args */
    ;
  new_argv = alloca (sizeof (char *) * (nargs + 3));	/* allocate new args */
  for (nargs = 0; argv[nargs] != NULL; nargs++)		/* copy old to new */
    new_argv[nargs] = argv[nargs];
  new_argv[nargs] = "-E";
  new_argv[nargs + 1] = bfd_big_endian (abfd) ? "big" : "little";
  new_argv[nargs + 2] = NULL;
  argv = new_argv;

  /* Create an instance of the simulator.  */
  default_callback.init (&default_callback);
  gdbsim_desc = sim_open (SIM_OPEN_STANDALONE, &default_callback, abfd, argv);
  if (gdbsim_desc == 0)
    exit (1);

  /* Load the program into the simulator.  */
  if (abfd)
    if (sim_load (gdbsim_desc, program, NULL, 0) == SIM_RC_FAIL)
      mygeneric_load (abfd);

  /* Create an inferior process in the simulator.  This initializes SP.  */
  sim_create_inferior (gdbsim_desc, abfd, argv, /* env */ NULL);
  sim_resume (gdbsim_desc, 1, 0);	/* execute one instr */
  return pid;
}

int
main (int argc, char **argv)
{
  char *name;
  char **prog_argv = NULL;
  struct bfd *prog_bfd;
  enum sim_stop reason;
  int sigrc = 0;
  int single_step = 0;
  RETSIGTYPE (*prev_sigint) ();

  myname = argv[0] + strlen (argv[0]);
  while (myname > argv[0] && myname[-1] != '/')
    --myname;

  /* INTERNAL: When MYNAME is `step', single step the simulator
     instead of allowing it to run free.  The sole purpose of this
     HACK is to allow the sim_resume interface's step argument to be
     tested without having to build/run gdb. */
  if (strlen (myname) > 4 && strcmp (myname - 4, "step") == 0)
    {
      single_step = 1;
    }

  /* Create an instance of the simulator.  */
  default_callback.init (&default_callback);
  sd = sim_open (SIM_OPEN_STANDALONE, &default_callback, NULL, argv);
  if (sd == 0)
    exit (1);
  if (STATE_MAGIC (sd) != SIM_MAGIC_NUMBER)
    {
      fprintf (stderr, "Internal error - bad magic number in simulator struct\n");
      abort ();
    }

  /* We can't set the endianness in the callback structure until
     sim_config is called, which happens in sim_open.  */
  default_callback.target_endian
    = (CURRENT_TARGET_BYTE_ORDER == BIG_ENDIAN
       ? BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE);

  /* Was there a program to run?  */
  prog_argv = STATE_PROG_ARGV (sd);
  prog_bfd = STATE_PROG_BFD (sd);
  if (prog_argv == NULL || *prog_argv == NULL)
    usage ();

  name = *prog_argv;

  /* For simulators that don't open prog during sim_open() */
  if (prog_bfd == NULL)
    {
      prog_bfd = bfd_openr (name, 0);
      if (prog_bfd == NULL)
	{
	  fprintf (stderr, "%s: can't open \"%s\": %s\n",
		   myname, name, bfd_errmsg (bfd_get_error ()));
	  exit (1);
	}
      if (!bfd_check_format (prog_bfd, bfd_object))
	{
	  fprintf (stderr, "%s: \"%s\" is not an object file: %s\n",
		   myname, name, bfd_errmsg (bfd_get_error ()));
	  exit (1);
	}
    }

  if (STATE_VERBOSE_P (sd))
    printf ("%s %s\n", myname, name);

  /* Load the program into the simulator.  */
  if (sim_load (sd, name, prog_bfd, 0) == SIM_RC_FAIL)
    exit (1);

  /* Prepare the program for execution.  */
#ifdef HAVE_ENVIRON
  sim_create_inferior (sd, prog_bfd, prog_argv, environ);
#else
  sim_create_inferior (sd, prog_bfd, prog_argv, NULL);
#endif

  /* To accommodate relative file paths, chdir to sysroot now.  We
     mustn't do this until BFD has opened the program, else we wouldn't
     find the executable if it has a relative file path.  */
  if (simulator_sysroot[0] != '\0' && chdir (simulator_sysroot) < 0)
    {
      fprintf (stderr, "%s: can't change directory to \"%s\"\n",
	       myname, simulator_sysroot);
      exit (1);
    }

  /* Run/Step the program.  */
  if (single_step)
    {
      do
	{
	  prev_sigint = signal (SIGINT, cntrl_c);
	  sim_resume (sd, 1/*step*/, 0);
	  signal (SIGINT, prev_sigint);
	  sim_stop_reason (sd, &reason, &sigrc);
//.........这里部分代码省略.........

void
kill_inferior (void)
{
  sim_close (gdbsim_desc, 0);
  default_callback.shutdown (&default_callback);
}