reg_ld_str.c

linux 内核源代码

/*---------------------------------------------------------------------------+
 |  reg_ld_str.c                                                             |
 |                                                                           |
 | All of the functions which transfer data between user memory and FPU_REGs.|
 |                                                                           |
 | Copyright (C) 1992,1993,1994,1996,1997                                    |
 |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
 |                  E-mail   [e-mail]                              |
 |                                                                           |
 |                                                                           |
 +---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------+
 | Note:                                                                     |
 |    The file contains code which accesses user memory.                     |
 |    Emulator static data may change when user memory is accessed, due to   |
 |    other processes using the emulator while swapping is in progress.      |
 +---------------------------------------------------------------------------*/

#include "fpu_emu.h"

#include <asm/uaccess.h>

#include "fpu_system.h"
#include "exception.h"
#include "reg_constant.h"
#include "control_w.h"
#include "status_w.h"


#define DOUBLE_Emax 1023         /* largest valid exponent */
#define DOUBLE_Ebias 1023
#define DOUBLE_Emin (-1022)      /* smallest valid exponent */

#define SINGLE_Emax 127          /* largest valid exponent */
#define SINGLE_Ebias 127
#define SINGLE_Emin (-126)       /* smallest valid exponent */


static u_char normalize_no_excep(FPU_REG *r, int exp, int sign)
{
  u_char tag;

  setexponent16(r, exp);

  tag = FPU_normalize_nuo(r);
  stdexp(r);
  if ( sign )
    setnegative(r);

  return tag;
}


int FPU_tagof(FPU_REG *ptr)
{
  int exp;

  exp = exponent16(ptr) & 0x7fff;
  if ( exp == 0 )
    {
      if ( !(ptr->sigh | ptr->sigl) )
	{
	  return TAG_Zero;
	}
      /* The number is a de-normal or pseudodenormal. */
      return TAG_Special;
    }

  if ( exp == 0x7fff )
    {
      /* Is an Infinity, a NaN, or an unsupported data type. */
      return TAG_Special;
    }

  if ( !(ptr->sigh & 0x80000000) )
    {
      /* Unsupported data type. */
      /* Valid numbers have the ms bit set to 1. */
      /* Unnormal. */
      return TAG_Special;
    }

  return TAG_Valid;
}


/* Get a long double from user memory */
int FPU_load_extended(long double __user *s, int stnr)
{
  FPU_REG *sti_ptr = &st(stnr);

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, s, 10);
  __copy_from_user(sti_ptr, s, 10);
  RE_ENTRANT_CHECK_ON;

  return FPU_tagof(sti_ptr);
}


/* Get a double from user memory */
int FPU_load_double(double __user *dfloat, FPU_REG *loaded_data)
{
  int exp, tag, negative;
  unsigned m64, l64;

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, dfloat, 8);
  FPU_get_user(m64, 1 + (unsigned long __user *) dfloat);
  FPU_get_user(l64, (unsigned long __user *) dfloat);
  RE_ENTRANT_CHECK_ON;

  negative = (m64 & 0x80000000) ? SIGN_Negative : SIGN_Positive;
  exp = ((m64 & 0x7ff00000) >> 20) - DOUBLE_Ebias + EXTENDED_Ebias;
  m64 &= 0xfffff;
  if ( exp > DOUBLE_Emax + EXTENDED_Ebias )
    {
      /* Infinity or NaN */
      if ((m64 == 0) && (l64 == 0))
	{
	  /* +- infinity */
	  loaded_data->sigh = 0x80000000;
	  loaded_data->sigl = 0x00000000;
	  exp = EXP_Infinity + EXTENDED_Ebias;
	  tag = TAG_Special;
	}
      else
	{
	  /* Must be a signaling or quiet NaN */
	  exp = EXP_NaN + EXTENDED_Ebias;
	  loaded_data->sigh = (m64 << 11) | 0x80000000;
	  loaded_data->sigh |= l64 >> 21;
	  loaded_data->sigl = l64 << 11;
	  tag = TAG_Special;    /* The calling function must look for NaNs */
	}
    }
  else if ( exp < DOUBLE_Emin + EXTENDED_Ebias )
    {
      /* Zero or de-normal */
      if ((m64 == 0) && (l64 == 0))
	{
	  /* Zero */
	  reg_copy(&CONST_Z, loaded_data);
	  exp = 0;
	  tag = TAG_Zero;
	}
      else
	{
	  /* De-normal */
	  loaded_data->sigh = m64 << 11;
	  loaded_data->sigh |= l64 >> 21;
	  loaded_data->sigl = l64 << 11;

	  return normalize_no_excep(loaded_data, DOUBLE_Emin, negative)
	    | (denormal_operand() < 0 ? FPU_Exception : 0);
	}
    }
  else
    {
      loaded_data->sigh = (m64 << 11) | 0x80000000;
      loaded_data->sigh |= l64 >> 21;
      loaded_data->sigl = l64 << 11;

      tag = TAG_Valid;
    }

  setexponent16(loaded_data, exp | negative);

  return tag;
}


/* Get a float from user memory */
int FPU_load_single(float __user *single, FPU_REG *loaded_data)
{
  unsigned m32;
  int exp, tag, negative;

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, single, 4);
  FPU_get_user(m32, (unsigned long __user *) single);
  RE_ENTRANT_CHECK_ON;

  negative = (m32 & 0x80000000) ? SIGN_Negative : SIGN_Positive;

  if (!(m32 & 0x7fffffff))
    {
      /* Zero */
      reg_copy(&CONST_Z, loaded_data);
      addexponent(loaded_data, negative);
      return TAG_Zero;
    }
  exp = ((m32 & 0x7f800000) >> 23) - SINGLE_Ebias + EXTENDED_Ebias;
  m32 = (m32 & 0x7fffff) << 8;
  if ( exp < SINGLE_Emin + EXTENDED_Ebias )
    {
      /* De-normals */
      loaded_data->sigh = m32;
      loaded_data->sigl = 0;

      return normalize_no_excep(loaded_data, SINGLE_Emin, negative)
	| (denormal_operand() < 0 ? FPU_Exception : 0);
    }
  else if ( exp > SINGLE_Emax + EXTENDED_Ebias )
    {
    /* Infinity or NaN */
      if ( m32 == 0 )
	{
	  /* +- infinity */
	  loaded_data->sigh = 0x80000000;
	  loaded_data->sigl = 0x00000000;
	  exp = EXP_Infinity + EXTENDED_Ebias;
	  tag = TAG_Special;
	}
      else
	{
	  /* Must be a signaling or quiet NaN */
	  exp = EXP_NaN + EXTENDED_Ebias;
	  loaded_data->sigh = m32 | 0x80000000;
	  loaded_data->sigl = 0;
	  tag = TAG_Special;  /* The calling function must look for NaNs */
	}
    }
  else
    {
      loaded_data->sigh = m32 | 0x80000000;
      loaded_data->sigl = 0;
      tag = TAG_Valid;
    }

  setexponent16(loaded_data, exp | negative);  /* Set the sign. */

  return tag;
}


/* Get a long long from user memory */
int FPU_load_int64(long long __user *_s)
{
  long long s;
  int sign;
  FPU_REG *st0_ptr = &st(0);

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, _s, 8);
  if (copy_from_user(&s,_s,8))
    FPU_abort;
  RE_ENTRANT_CHECK_ON;

  if (s == 0)
    {
      reg_copy(&CONST_Z, st0_ptr);
      return TAG_Zero;
    }

  if (s > 0)
    sign = SIGN_Positive;
  else
  {
    s = -s;
    sign = SIGN_Negative;
  }

  significand(st0_ptr) = s;

  return normalize_no_excep(st0_ptr, 63, sign);
}


/* Get a long from user memory */
int FPU_load_int32(long __user *_s, FPU_REG *loaded_data)
{
  long s;
  int negative;

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, _s, 4);
  FPU_get_user(s, _s);
  RE_ENTRANT_CHECK_ON;

  if (s == 0)
    { reg_copy(&CONST_Z, loaded_data); return TAG_Zero; }

  if (s > 0)
    negative = SIGN_Positive;
  else
    {
      s = -s;
      negative = SIGN_Negative;
    }

  loaded_data->sigh = s;
  loaded_data->sigl = 0;

  return normalize_no_excep(loaded_data, 31, negative);
}


/* Get a short from user memory */
int FPU_load_int16(short __user *_s, FPU_REG *loaded_data)
{
  int s, negative;

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, _s, 2);
  /* Cast as short to get the sign extended. */
  FPU_get_user(s, _s);
  RE_ENTRANT_CHECK_ON;

  if (s == 0)
    { reg_copy(&CONST_Z, loaded_data); return TAG_Zero; }

  if (s > 0)
    negative = SIGN_Positive;
  else
    {
      s = -s;
      negative = SIGN_Negative;
    }

  loaded_data->sigh = s << 16;
  loaded_data->sigl = 0;

  return normalize_no_excep(loaded_data, 15, negative);
}


/* Get a packed bcd array from user memory */
int FPU_load_bcd(u_char __user *s)
{
  FPU_REG *st0_ptr = &st(0);
  int pos;
  u_char bcd;
  long long l=0;
  int sign;

  RE_ENTRANT_CHECK_OFF;
  FPU_access_ok(VERIFY_READ, s, 10);
  RE_ENTRANT_CHECK_ON;
  for ( pos = 8; pos >= 0; pos--)
    {
      l *= 10;
      RE_ENTRANT_CHECK_OFF;
      FPU_get_user(bcd, s+pos);
      RE_ENTRANT_CHECK_ON;
      l += bcd >> 4;
      l *= 10;
      l += bcd & 0x0f;
    }
 
  RE_ENTRANT_CHECK_OFF;
  FPU_get_user(sign, s+9);
  sign = sign & 0x80 ? SIGN_Negative : SIGN_Positive;
  RE_ENTRANT_CHECK_ON;

  if ( l == 0 )
    {
      reg_copy(&CONST_Z, st0_ptr);
      addexponent(st0_ptr, sign);   /* Set the sign. */
      return TAG_Zero;
    }
  else
    {
      significand(st0_ptr) = l;
      return normalize_no_excep(st0_ptr, 63, sign);
    }
}

/*===========================================================================*/

/* Put a long double into user memory */
int FPU_store_extended(FPU_REG *st0_ptr, u_char st0_tag, long double __user *d)
{
  /*
    The only exception raised by an attempt to store to an
    extended format is the Invalid Stack exception, i.e.
    attempting to store from an empty register.
   */

  if ( st0_tag != TAG_Empty )
    {
      RE_ENTRANT_CHECK_OFF;
      FPU_access_ok(VERIFY_WRITE, d, 10);

      FPU_put_user(st0_ptr->sigl, (unsigned long __user *) d);
      FPU_put_user(st0_ptr->sigh, (unsigned long __user *) ((u_char __user *)d + 4));
      FPU_put_user(exponent16(st0_ptr), (unsigned short __user *) ((u_char __user *)d + 8));
      RE_ENTRANT_CHECK_ON;

      return 1;
    }

  /* Empty register (stack underflow) */
  EXCEPTION(EX_StackUnder);
  if ( control_word & CW_Invalid )
    {
      /* The masked response */
      /* Put out the QNaN indefinite */
      RE_ENTRANT_CHECK_OFF;
      FPU_access_ok(VERIFY_WRITE,d,10);
      FPU_put_user(0, (unsigned long __user *) d);
      FPU_put_user(0xc0000000, 1 + (unsigned long __user *) d);
      FPU_put_user(0xffff, 4 + (short __user *) d);
      RE_ENTRANT_CHECK_ON;
      return 1;
    }
  else
    return 0;

}


/* Put a double into user memory */
int FPU_store_double(FPU_REG *st0_ptr, u_char st0_tag, double __user *dfloat)
{
  unsigned long l[2];
  unsigned long increment = 0;	/* avoid gcc warnings */
  int precision_loss;
  int exp;
  FPU_REG tmp;

  if ( st0_tag == TAG_Valid )
    {
      reg_copy(st0_ptr, &tmp);
      exp = exponent(&tmp);

      if ( exp < DOUBLE_Emin )     /* It may be a denormal */
	{
	  addexponent(&tmp, -DOUBLE_Emin + 52);  /* largest exp to be 51 */

	denormal_arg:

	  if ( (precision_loss = FPU_round_to_int(&tmp, st0_tag)) )
	    {
#ifdef PECULIAR_486
	      /* Did it round to a non-denormal ? */
	      /* This behaviour might be regarded as peculiar, it appears
		 that the 80486 rounds to the dest precision, then
		 converts to decide underflow. */
	      if ( !((tmp.sigh == 0x00100000) && (tmp.sigl == 0) &&
		  (st0_ptr->sigl & 0x000007ff)) )
#endif /* PECULIAR_486 */
		{
		  EXCEPTION(EX_Underflow);
		  /* This is a special case: see sec 16.2.5.1 of
		     the 80486 book */
		  if ( !(control_word & CW_Underflow) )
		    return 0;
		}
	      EXCEPTION(precision_loss);
	      if ( !(control_word & CW_Precision) )
		return 0;
	    }
	  l[0] = tmp.sigl;
	  l[1] = tmp.sigh;
	}
      else
	{