m68k-pinsn.c

早期freebsd实现

      /* Get register number assuming address register.  */
      regno = (val & 7) + 8;
      regname = reg_names[regno];
      switch (val >> 3)
	{
	case 0:
	  fprintf_filtered (stream, "%s", reg_names[val]);
	  break;

	case 1:
	  fprintf_filtered (stream, "%s", regname);
	  break;

	case 2:
	  fprintf_filtered (stream, "%s@", regname);
	  break;

	case 3:
	  fprintf_filtered (stream, "%s@+", regname);
	  break;

	case 4:
	  fprintf_filtered (stream, "%s@-", regname);
	  break;

	case 5:
	  val = NEXTWORD (p);
	  fprintf_filtered (stream, "%s@(%d)", regname, val);
	  break;

	case 6:
	  p = print_indexed (regno, p, addr, stream);
	  break;

	case 7:
	  switch (val & 7)
	    {
	    case 0:
	      val = NEXTWORD (p);
	      fprintf_filtered (stream, "@#");
	      print_address (val, stream);
	      break;

	    case 1:
	      val = NEXTLONG (p);
	      fprintf_filtered (stream, "@#");
	      print_address (val, stream);
	      break;

	    case 2:
	      val = NEXTWORD (p);
	      print_address (addr + val, stream);
	      break;

	    case 3:
	      p = print_indexed (-1, p, addr, stream);
	      break;

	    case 4:
	      flt_p = 1;	/* Assume it's a float... */
	      switch( place )
	      {
		case 'b':
		  val = NEXTBYTE (p);
		  flt_p = 0;
		  break;

		case 'w':
		  val = NEXTWORD (p);
		  flt_p = 0;
		  break;

		case 'l':
		  val = NEXTLONG (p);
		  flt_p = 0;
		  break;

		case 'f':
		  flval = NEXTSINGLE(p);
		  break;

		case 'F':
		  flval = NEXTDOUBLE(p);
		  break;

#ifdef HAVE_68881
		case 'x':
		  ieee_extended_to_double (&ext_format_68881, p, &flval);
		  p += 12;
		  break;
#endif

		case 'p':
		  p += 12;
		  flval = 0;	/* FIXME, handle packed decimal someday.  */
		  break;

		default:
		  error ("Invalid arg format in opcode table: \"%c%c\".",
		       *d, place);
	      }
	      if ( flt_p )	/* Print a float? */
		fprintf_filtered (stream, "#%g", flval);
	      else
		fprintf_filtered (stream, "#%d", val);
	      break;

	    default:
	      fprintf_filtered (stream, "<invalid address mode 0%o>", val);
	    }
	}
      break;

    case 'L':
    case 'l':
	if (place == 'w')
	  {
	    char doneany;
	    p1 = buffer + 2;
	    val = NEXTWORD (p1);
	    /* Move the pointer ahead if this point is farther ahead
	       than the last.  */
	    p = p1 > p ? p1 : p;
	    if (val == 0)
	      {
		fputs_filtered ("#0", stream);
		break;
	      }
	    if (*d == 'l')
	      {
		register int newval = 0;
		for (regno = 0; regno < 16; ++regno)
		  if (val & (0x8000 >> regno))
		    newval |= 1 << regno;
		val = newval;
	      }
	    val &= 0xffff;
	    doneany = 0;
	    for (regno = 0; regno < 16; ++regno)
	      if (val & (1 << regno))
		{
		  int first_regno;
		  if (doneany)
		    fputs_filtered ("/", stream);
		  doneany = 1;
		  fprintf_filtered (stream, "%s", reg_names[regno]);
		  first_regno = regno;
		  while (val & (1 << (regno + 1)))
		    ++regno;
		  if (regno > first_regno)
		    fprintf_filtered (stream, "-%s", reg_names[regno]);
		}
	  }
	else if (place == '3')
	  {
	    /* `fmovem' insn.  */
	    char doneany;
	    val = fetch_arg (buffer, place, 8);
	    if (val == 0)
	      {
		fputs_filtered ("#0", stream);
		break;
	      }
	    if (*d == 'l')
	      {
		register int newval = 0;
		for (regno = 0; regno < 8; ++regno)
		  if (val & (0x80 >> regno))
		    newval |= 1 << regno;
		val = newval;
	      }
	    val &= 0xff;
	    doneany = 0;
	    for (regno = 0; regno < 8; ++regno)
	      if (val & (1 << regno))
		{
		  int first_regno;
		  if (doneany)
		    fputs_filtered ("/", stream);
		  doneany = 1;
		  fprintf_filtered (stream, "fp%d", regno);
		  first_regno = regno;
		  while (val & (1 << (regno + 1)))
		    ++regno;
		  if (regno > first_regno)
		    fprintf_filtered (stream, "-fp%d", regno);
		}
	  }
	else
	  goto de_fault;
      break;

    default:  de_fault:
      error ("Invalid arg format in opcode table: \"%c\".", *d);
    }

  return (unsigned char *) p;
}

/* Fetch BITS bits from a position in the instruction specified by CODE.
   CODE is a "place to put an argument", or 'x' for a destination
   that is a general address (mode and register).
   BUFFER contains the instruction.  */

static int
fetch_arg (buffer, code, bits)
     unsigned char *buffer;
     int code;
     int bits;
{
  register int val;
  switch (code)
    {
    case 's':
      val = buffer[1];
      break;

    case 'd':			/* Destination, for register or quick.  */
      val = (buffer[0] << 8) + buffer[1];
      val >>= 9;
      break;

    case 'x':			/* Destination, for general arg */
      val = (buffer[0] << 8) + buffer[1];
      val >>= 6;
      break;

    case 'k':
      val = (buffer[3] >> 4);
      break;

    case 'C':
      val = buffer[3];
      break;

    case '1':
      val = (buffer[2] << 8) + buffer[3];
      val >>= 12;
      break;

    case '2':
      val = (buffer[2] << 8) + buffer[3];
      val >>= 6;
      break;

    case '3':
    case 'j':
      val = (buffer[2] << 8) + buffer[3];
      break;

    case '4':
      val = (buffer[4] << 8) + buffer[5];
      val >>= 12;
      break;

    case '5':
      val = (buffer[4] << 8) + buffer[5];
      val >>= 6;
      break;

    case '6':
      val = (buffer[4] << 8) + buffer[5];
      break;

    case '7':
      val = (buffer[2] << 8) + buffer[3];
      val >>= 7;
      break;
      
    case '8':
      val = (buffer[2] << 8) + buffer[3];
      val >>= 10;
      break;

    case 'e':
      val = (buffer[1] >> 6);
      break;

    default:
      abort ();
    }

  switch (bits)
    {
    case 2:
      return val & 3;
    case 3:
      return val & 7;
    case 4:
      return val & 017;
    case 5:
      return val & 037;
    case 6:
      return val & 077;
    case 7:
      return val & 0177;
    case 8:
      return val & 0377;
    case 12:
      return val & 07777;
    default:
      abort ();
    }
}

/* Print an indexed argument.  The base register is BASEREG (-1 for pc).
   P points to extension word, in buffer.
   ADDR is the nominal core address of that extension word.  */

static unsigned char *
print_indexed (basereg, p, addr, stream)
     int basereg;
     unsigned char *p;
     CORE_ADDR addr;
     FILE *stream;
{
  register int word;
  static char *scales[] = {"", "*2", "*4", "*8"};
  register int base_disp;
  register int outer_disp;
  char buf[40];

  word = NEXTWORD (p);

  /* Generate the text for the index register.
     Where this will be output is not yet determined.  */
  sprintf (buf, "[%s.%c%s]",
	   reg_names[(word >> 12) & 0xf],
	   (word & 0x800) ? 'l' : 'w',
	   scales[(word >> 9) & 3]);

  /* Handle the 68000 style of indexing.  */

  if ((word & 0x100) == 0)
    {
      print_base (basereg,
		  ((word & 0x80) ? word | 0xff00 : word & 0xff)
		  + ((basereg == -1) ? addr : 0),
		  stream);
      fputs_filtered (buf, stream);
      return p;
    }

  /* Handle the generalized kind.  */
  /* First, compute the displacement to add to the base register.  */

  if (word & 0200)
    basereg = -2;
  if (word & 0100)
    buf[0] = 0;
  base_disp = 0;
  switch ((word >> 4) & 3)
    {
    case 2:
      base_disp = NEXTWORD (p);
      break;
    case 3:
      base_disp = NEXTLONG (p);
    }
  if (basereg == -1)
    base_disp += addr;

  /* Handle single-level case (not indirect) */

  if ((word & 7) == 0)
    {
      print_base (basereg, base_disp, stream);
      fputs_filtered (buf, stream);
      return p;
    }

  /* Two level.  Compute displacement to add after indirection.  */

  outer_disp = 0;
  switch (word & 3)
    {
    case 2:
      outer_disp = NEXTWORD (p);
      break;
    case 3:
      outer_disp = NEXTLONG (p);
    }

  fprintf_filtered (stream, "%d(", outer_disp);
  print_base (basereg, base_disp, stream);

  /* If postindexed, print the closeparen before the index.  */
  if (word & 4)
    fprintf_filtered (stream, ")%s", buf);
  /* If preindexed, print the closeparen after the index.  */
  else
    fprintf_filtered (stream, "%s)", buf);

  return p;
}

/* Print a base register REGNO and displacement DISP, on STREAM.
   REGNO = -1 for pc, -2 for none (suppressed).  */

static void
print_base (regno, disp, stream)
     int regno;
     int disp;
     FILE *stream;
{
  if (regno == -2)
    fprintf_filtered (stream, "%d", disp);
  else if (regno == -1)
    fprintf_filtered (stream, "0x%x", disp);
  else
    fprintf_filtered (stream, "%d(%s)", disp, reg_names[regno]);
}