i387-tdep.c   [plain text]

/* Intel 387 floating point stuff.
   Copyright (C) 1988, 89, 91, 98, 99, 2000 Free Software Foundation, Inc.

   This file is part of GDB.

   This program 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 of the License, or
   (at your option) any later version.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include "defs.h"
#include "frame.h"
#include "inferior.h"
#include "language.h"
#include "value.h"
#include "gdbcore.h"
#include "floatformat.h"


/* FIXME: Eliminate the next two functions when we have the time to
   change all the callers.  */

void i387_to_double (char *from, char *to);
void double_to_i387 (char *from, char *to);

void
i387_to_double (char *from, char *to)
{
  floatformat_to_double (&floatformat_i387_ext, from, (double *) to);
}

void
double_to_i387 (char *from, char *to)
{
  floatformat_from_double (&floatformat_i387_ext, (double *) from, to);
}


/* FIXME: The functions on this page are used by the old `info float'
   implementations that a few of the i386 targets provide.  These
   functions should be removed if all of these have been converted to
   use the generic implementation based on the new register file
   layout.  */

static void print_387_control_bits (unsigned int control);
static void print_387_status_bits (unsigned int status);

static void
print_387_control_bits (unsigned int control)
{
  switch ((control >> 8) & 3)
    {
    case 0:
      puts_unfiltered (" 24 bit; ");
      break;
    case 1:
      puts_unfiltered (" (bad); ");
      break;
    case 2:
      puts_unfiltered (" 53 bit; ");
      break;
    case 3:
      puts_unfiltered (" 64 bit; ");
      break;
    }
  switch ((control >> 10) & 3)
    {
    case 0:
      puts_unfiltered ("NEAR; ");
      break;
    case 1:
      puts_unfiltered ("DOWN; ");
      break;
    case 2:
      puts_unfiltered ("UP; ");
      break;
    case 3:
      puts_unfiltered ("CHOP; ");
      break;
    }
  if (control & 0x3f)
    {
      puts_unfiltered ("mask");
      if (control & 0x0001)
	puts_unfiltered (" INVAL");
      if (control & 0x0002)
	puts_unfiltered (" DENOR");
      if (control & 0x0004)
	puts_unfiltered (" DIVZ");
      if (control & 0x0008)
	puts_unfiltered (" OVERF");
      if (control & 0x0010)
	puts_unfiltered (" UNDER");
      if (control & 0x0020)
	puts_unfiltered (" LOS");
      puts_unfiltered (";");
    }

  if (control & 0xe080)
    warning ("\nreserved bits on: %s",
	     local_hex_string (control & 0xe080));
}

void
print_387_control_word (unsigned int control)
{
  printf_filtered ("control %s:", local_hex_string(control & 0xffff));
  print_387_control_bits (control);
  puts_unfiltered ("\n");
}

static void
print_387_status_bits (unsigned int status)
{
  printf_unfiltered (" flags %d%d%d%d; ",
		     (status & 0x4000) != 0,
		     (status & 0x0400) != 0,
		     (status & 0x0200) != 0,
		     (status & 0x0100) != 0);
  printf_unfiltered ("top %d; ", (status >> 11) & 7);
  if (status & 0xff) 
    {
      puts_unfiltered ("excep");
      if (status & 0x0001) puts_unfiltered (" INVAL");
      if (status & 0x0002) puts_unfiltered (" DENOR");
      if (status & 0x0004) puts_unfiltered (" DIVZ");
      if (status & 0x0008) puts_unfiltered (" OVERF");
      if (status & 0x0010) puts_unfiltered (" UNDER");
      if (status & 0x0020) puts_unfiltered (" LOS");
      if (status & 0x0040) puts_unfiltered (" STACK");
    }
}

void
print_387_status_word (unsigned int status)
{
  printf_filtered ("status %s:", local_hex_string (status & 0xffff));
  print_387_status_bits (status);
  puts_unfiltered ("\n");
}


/* Implement the `info float' layout based on the register definitions
   in `tm-i386.h'.  */

/* Print the floating point number specified by RAW.  */
static void
print_i387_value (char *raw)
{
  DOUBLEST value;

  /* Avoid call to floatformat_to_doublest if possible to preserve as
     much information as possible.  */

#ifdef HAVE_LONG_DOUBLE
  if (sizeof (value) == sizeof (long double)
      && HOST_LONG_DOUBLE_FORMAT == &floatformat_i387_ext)
    {
      /* Copy straight over, but take care of the padding.  */
      memcpy (&value, raw, FPU_REG_RAW_SIZE);
      memset ((char *) &value + FPU_REG_RAW_SIZE, 0,
	      sizeof (value) - FPU_REG_RAW_SIZE);
    }
  else
#endif
    floatformat_to_doublest (&floatformat_i387_ext, raw, &value);

  /* We try to print 19 digits.  The last digit may or may not contain
     garbage, but we'd better print one too many.  We need enough room
     to print the value, 1 position for the sign, 1 for the decimal
     point, 19 for the digits and 6 for the exponent adds up to 27.  */
#ifdef PRINTF_HAS_LONG_DOUBLE
  printf_filtered (" %-+27.19Lg", (long double) value);
#else
  printf_filtered (" %-+27.19g", (double) value);
#endif
}

/* Print the classification for the register contents RAW.  */
static void
print_i387_ext (unsigned char *raw)
{
  int sign;
  int integer;
  unsigned int exponent;
  unsigned long fraction[2];

  sign = raw[9] & 0x80;
  integer = raw[7] & 0x80;
  exponent = (((raw[9] & 0x7f) << 8) | raw[8]);
  fraction[0] = ((raw[3] << 24) | (raw[2] << 16) | (raw[1] << 8) | raw[0]);
  fraction[1] = (((raw[7] & 0x7f) << 24) | (raw[6] << 16)
		 | (raw[5] << 8) | raw[4]);

  if (exponent == 0x7fff && integer)
    {
      if (fraction[0] == 0x00000000 && fraction[1] == 0x00000000)
	/* Infinity.  */
	printf_filtered (" %cInf", (sign ? '-' : '+'));
      else if (sign && fraction[0] == 0x00000000 && fraction[1] == 0x40000000)
	/* Real Indefinite (QNaN).  */
	puts_unfiltered (" Real Indefinite (QNaN)");
      else if (fraction[1] & 0x40000000)
	/* QNaN.  */
	puts_filtered (" QNaN");
      else
	/* SNaN.  */
	puts_filtered (" SNaN");
    }
  else if (exponent < 0x7fff && exponent > 0x0000 && integer)
    /* Normal.  */
    print_i387_value (raw);
  else if (exponent == 0x0000)
    {
      /* Denormal or zero.  */
      print_i387_value (raw);
      
      if (integer)
	/* Pseudo-denormal.  */
	puts_filtered (" Pseudo-denormal");
      else if (fraction[0] || fraction[1])
	/* Denormal.  */
	puts_filtered (" Denormal");
    }
  else
    /* Unsupported.  */
    puts_filtered (" Unsupported");
}

/* Print the status word STATUS.  */
static void
print_i387_status_word (unsigned int status)
{
  printf_filtered ("Status Word:         %s",
		   local_hex_string_custom (status, "04"));
  puts_filtered ("  ");
  printf_filtered (" %s", (status & 0x0001) ? "IE" : "  ");
  printf_filtered (" %s", (status & 0x0002) ? "DE" : "  ");
  printf_filtered (" %s", (status & 0x0004) ? "ZE" : "  ");
  printf_filtered (" %s", (status & 0x0008) ? "OE" : "  ");
  printf_filtered (" %s", (status & 0x0010) ? "UE" : "  ");
  printf_filtered (" %s", (status & 0x0020) ? "PE" : "  ");
  puts_filtered ("  ");
  printf_filtered (" %s", (status & 0x0080) ? "ES" : "  ");
  puts_filtered ("  ");
  printf_filtered (" %s", (status & 0x0080) ? "SF" : "  ");
  puts_filtered ("  ");
  printf_filtered (" %s", (status & 0x0100) ? "C0" : "  ");
  printf_filtered (" %s", (status & 0x0200) ? "C1" : "  ");
  printf_filtered (" %s", (status & 0x0400) ? "C2" : "  ");
  printf_filtered (" %s", (status & 0x4000) ? "C3" : "  ");

  puts_filtered ("\n");

  printf_filtered ("                       TOP: %d\n", ((status >> 11) & 7));
}

/* Print the control word CONTROL.  */
static void
print_i387_control_word (unsigned int control)
{
  printf_filtered ("Control Word:        %s",
		   local_hex_string_custom (control, "04"));
  puts_filtered ("  ");
  printf_filtered (" %s", (control & 0x0001) ? "IM" : "  ");
  printf_filtered (" %s", (control & 0x0002) ? "DM" : "  ");
  printf_filtered (" %s", (control & 0x0004) ? "ZM" : "  ");
  printf_filtered (" %s", (control & 0x0008) ? "OM" : "  ");
  printf_filtered (" %s", (control & 0x0010) ? "UM" : "  ");
  printf_filtered (" %s", (control & 0x0020) ? "PM" : "  ");

  puts_filtered ("\n");

  puts_filtered ("                       PC: ");
  switch ((control >> 8) & 3)
    {
    case 0:
      puts_filtered ("Single Precision (24-bits)\n");
      break;
    case 1:
      puts_filtered ("Reserved\n");
      break;
    case 2:
      puts_filtered ("Double Precision (53-bits)\n");
      break;
    case 3:
      puts_filtered ("Extended Precision (64-bits)\n");
      break;
    }
      
  puts_filtered ("                       RC: ");
  switch ((control >> 10) & 3)
    {
    case 0:
      puts_filtered ("Round to nearest\n");
      break;
    case 1:
      puts_filtered ("Round down\n");
      break;
    case 2:
      puts_filtered ("Round up\n");
      break;
    case 3:
      puts_filtered ("Round toward zero\n");
      break;
    }
}

/* Print out the i387 floating poin state.  */
void
i387_float_info (void)
{
  unsigned int fctrl;
  unsigned int fstat;
  unsigned int ftag;
  unsigned int fiseg;
  unsigned int fioff;
  unsigned int foseg;
  unsigned int fooff;
  unsigned int fop;
  int fpreg;
  int top;

  fctrl = read_register (FCTRL_REGNUM);
  fstat = read_register (FSTAT_REGNUM);
  ftag  = read_register (FTAG_REGNUM);
  fiseg = read_register (FCS_REGNUM);
  fioff = read_register (FCOFF_REGNUM);
  foseg = read_register (FDS_REGNUM);
  fooff = read_register (FDOFF_REGNUM);
  fop   = read_register (FOP_REGNUM);
  
  top = ((fstat >> 11) & 7);

  for (fpreg = 7; fpreg >= 0; fpreg--)
    {
      unsigned char raw[FPU_REG_RAW_SIZE];
      int tag = (ftag >> (fpreg * 2)) & 3;
      int i;

      printf_filtered ("%sR%d: ", fpreg == top ? "=>" : "  ", fpreg);

      switch (tag)
	{
	case 0:
	  puts_filtered ("Valid   ");
	  break;
	case 1:
	  puts_filtered ("Zero    ");
	  break;
	case 2:
	  puts_filtered ("Special ");
	  break;
	case 3:
	  puts_filtered ("Empty   ");
	  break;
	}

      read_register_gen ((fpreg + 8 - top) % 8 + FP0_REGNUM, raw);

      puts_filtered ("0x");
      for (i = 9; i >= 0; i--)
	printf_filtered ("%02x", raw[i]);

      if (tag != 3)
	print_i387_ext (raw);

      puts_filtered ("\n");
    }

  puts_filtered ("\n");

  print_i387_status_word (fstat);
  print_i387_control_word (fctrl);
  printf_filtered ("Tag Word:            %s\n",
		   local_hex_string_custom (ftag, "04"));
  printf_filtered ("Instruction Pointer: %s:",
		   local_hex_string_custom (fiseg, "02"));
  printf_filtered ("%s\n", local_hex_string_custom (fioff, "08"));
  printf_filtered ("Operand Pointer:     %s:",
		   local_hex_string_custom (foseg, "02"));
  printf_filtered ("%s\n", local_hex_string_custom (fooff, "08"));
  printf_filtered ("Opcode:              %s\n",
		   local_hex_string_custom (fop ? (fop | 0xd800) : 0, "04"));
}