for (i=0; i<6; i++)
{
  short check_i;
  int check_args;

  length = (unsigned short) receive(PIC, buf);
  check_args = decode(buf, length, "joint %d=%#lf", &check_i, precision, &x[i]);

  if (check_args != 2 || check_i != i)
	fprintf(stderr, "bad message %d\n", check_i);
}
