gdb/gdbserver/i387-fp.c

/* i387-specific utility functions, for the remote server for GDB.
   Copyright (C) 2000, 2001, 2002, 2005, 2007, 2008, 2009
   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 3 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, see <http://www.gnu.org/licenses/>.  */

#include "server.h"
#include "i387-fp.h"

int num_xmm_registers = 8;

/* Note: These functions preserve the reserved bits in control registers.
   However, gdbserver promptly throws away that information.  */

/* These structs should have the proper sizes and alignment on both
   i386 and x86-64 machines.  */

struct i387_fsave {
  /* All these are only sixteen bits, plus padding, except for fop (which
     is only eleven bits), and fooff / fioff (which are 32 bits each).  */
  unsigned short fctrl;
  unsigned short pad1;
  unsigned short fstat;
  unsigned short pad2;
  unsigned short ftag;
  unsigned short pad3;
  unsigned int fioff;
  unsigned short fiseg;
  unsigned short fop;
  unsigned int fooff;
  unsigned short foseg;
  unsigned short pad4;

  /* Space for eight 80-bit FP values.  */
  unsigned char st_space[80];
};

struct i387_fxsave {
  /* All these are only sixteen bits, plus padding, except for fop (which
     is only eleven bits), and fooff / fioff (which are 32 bits each).  */
  unsigned short fctrl;
  unsigned short fstat;
  unsigned short ftag;
  unsigned short fop;
  unsigned int fioff;
  unsigned short fiseg;
  unsigned short pad1;
  unsigned int fooff;
  unsigned short foseg;
  unsigned short pad12;

  unsigned int mxcsr;
  unsigned int pad3;

  /* Space for eight 80-bit FP values in 128-bit spaces.  */
  unsigned char st_space[128];

  /* Space for eight 128-bit XMM values, or 16 on x86-64.  */
  unsigned char xmm_space[256];
};

void
i387_cache_to_fsave (void *buf)
{
  struct i387_fsave *fp = (struct i387_fsave *) buf;
  int i;
  int st0_regnum = find_regno ("st0");
  unsigned long val, val2;

  for (i = 0; i < 8; i++)
    collect_register (i + st0_regnum, ((char *) &fp->st_space[0]) + i * 10);

  collect_register_by_name ("fioff", &fp->fioff);
  collect_register_by_name ("fooff", &fp->fooff);
  
  /* This one's 11 bits... */
  collect_register_by_name ("fop", &val2);
  fp->fop = (val2 & 0x7FF) | (fp->fop & 0xF800);

  /* Some registers are 16-bit.  */
  collect_register_by_name ("fctrl", &val);
  fp->fctrl = val;

  collect_register_by_name ("fstat", &val);
  val &= 0xFFFF;
  fp->fstat = val;

  collect_register_by_name ("ftag", &val);
  val &= 0xFFFF;
  fp->ftag = val;

  collect_register_by_name ("fiseg", &val);
  val &= 0xFFFF;
  fp->fiseg = val;

  collect_register_by_name ("foseg", &val);
  val &= 0xFFFF;
  fp->foseg = val;
}

void
i387_fsave_to_cache (const void *buf)
{
  struct i387_fsave *fp = (struct i387_fsave *) buf;
  int i;
  int st0_regnum = find_regno ("st0");
  unsigned long val;

  for (i = 0; i < 8; i++)
    supply_register (i + st0_regnum, ((char *) &fp->st_space[0]) + i * 10);

  supply_register_by_name ("fioff", &fp->fioff);
  supply_register_by_name ("fooff", &fp->fooff);

  /* Some registers are 16-bit.  */
  val = fp->fctrl & 0xFFFF;
  supply_register_by_name ("fctrl", &val);

  val = fp->fstat & 0xFFFF;
  supply_register_by_name ("fstat", &val);

  val = fp->ftag & 0xFFFF;
  supply_register_by_name ("ftag", &val);

  val = fp->fiseg & 0xFFFF;
  supply_register_by_name ("fiseg", &val);

  val = fp->foseg & 0xFFFF;
  supply_register_by_name ("foseg", &val);

  /* fop has only 11 valid bits.  */
  val = (fp->fop) & 0x7FF;
  supply_register_by_name ("fop", &val);
}

void
i387_cache_to_fxsave (void *buf)
{
  struct i387_fxsave *fp = (struct i387_fxsave *) buf;
  int i;
  int st0_regnum = find_regno ("st0");
  int xmm0_regnum = find_regno ("xmm0");
  unsigned long val, val2;

  for (i = 0; i < 8; i++)
    collect_register (i + st0_regnum, ((char *) &fp->st_space[0]) + i * 16);
  for (i = 0; i < num_xmm_registers; i++)
    collect_register (i + xmm0_regnum, ((char *) &fp->xmm_space[0]) + i * 16);

  collect_register_by_name ("fioff", &fp->fioff);
  collect_register_by_name ("fooff", &fp->fooff);
  collect_register_by_name ("mxcsr", &fp->mxcsr);

  /* This one's 11 bits... */
  collect_register_by_name ("fop", &val2);
  fp->fop = (val2 & 0x7FF) | (fp->fop & 0xF800);

  /* Some registers are 16-bit.  */
  collect_register_by_name ("fctrl", &val);
  fp->fctrl = val;

  collect_register_by_name ("fstat", &val);
  fp->fstat = val;

  /* Convert to the simplifed tag form stored in fxsave data.  */
  collect_register_by_name ("ftag", &val);
  val &= 0xFFFF;
  val2 = 0;
  for (i = 7; i >= 0; i--)
    {
      int tag = (val >> (i * 2)) & 3;

      if (tag != 3)
	val2 |= (1 << i);
    }
  fp->ftag = val2;

  collect_register_by_name ("fiseg", &val);
  fp->fiseg = val;

  collect_register_by_name ("foseg", &val);
  fp->foseg = val;
}

static int
i387_ftag (struct i387_fxsave *fp, int regno)
{
  unsigned char *raw = &fp->st_space[regno * 16];
  unsigned int exponent;
  unsigned long fraction[2];
  int integer;

  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)
    {
      /* Special.  */
      return (2);
    }
  else if (exponent == 0x0000)
    {
      if (fraction[0] == 0x0000 && fraction[1] == 0x0000 && !integer)
	{
	  /* Zero.  */
	  return (1);
	}
      else
	{
	  /* Special.  */
	  return (2);
	}
    }
  else
    {
      if (integer)
	{
	  /* Valid.  */
	  return (0);
	}
      else
	{
	  /* Special.  */
	  return (2);
	}
    }
}

void
i387_fxsave_to_cache (const void *buf)
{
  struct i387_fxsave *fp = (struct i387_fxsave *) buf;
  int i, top;
  int st0_regnum = find_regno ("st0");
  int xmm0_regnum = find_regno ("xmm0");
  unsigned long val;

  for (i = 0; i < 8; i++)
    supply_register (i + st0_regnum, ((char *) &fp->st_space[0]) + i * 16);
  for (i = 0; i < num_xmm_registers; i++)
    supply_register (i + xmm0_regnum, ((char *) &fp->xmm_space[0]) + i * 16);

  supply_register_by_name ("fioff", &fp->fioff);
  supply_register_by_name ("fooff", &fp->fooff);
  supply_register_by_name ("mxcsr", &fp->mxcsr);

  /* Some registers are 16-bit.  */
  val = fp->fctrl & 0xFFFF;
  supply_register_by_name ("fctrl", &val);

  val = fp->fstat & 0xFFFF;
  supply_register_by_name ("fstat", &val);

  /* Generate the form of ftag data that GDB expects.  */
  top = (fp->fstat >> 11) & 0x7;
  val = 0;
  for (i = 7; i >= 0; i--)
    {
      int tag;
      if (fp->ftag & (1 << i))
	tag = i387_ftag (fp, (i + 8 - top) % 8);
      else
	tag = 3;
      val |= tag << (2 * i);
    }
  supply_register_by_name ("ftag", &val);

  val = fp->fiseg & 0xFFFF;
  supply_register_by_name ("fiseg", &val);

  val = fp->foseg & 0xFFFF;
  supply_register_by_name ("foseg", &val);

  val = (fp->fop) & 0x7FF;
  supply_register_by_name ("fop", &val);
}