fpu_trig.c

linux 内核源代码

	      if ( arith_invalid(1) < 0 )
		return;
	    }
	  else if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;
	  else
	    {
	      if ( exponent(st0_ptr) < 0 )
		sign ^= SIGN_NEG;

	      FPU_copy_to_reg1(&CONST_Z, TAG_Zero);
	      setsign(st1_ptr, sign);
	    }
	}
      else
	{
	  /* One or both operands are denormals. */
	  if ( denormal_operand() < 0 )
	    return;
	  goto both_valid;
	}
    }
  else if ( (st0_tag == TW_NaN) || (st1_tag == TW_NaN) )
    {
      if ( real_2op_NaN(st0_ptr, st0_tag, 1, st0_ptr) < 0 )
	return;
    }
  /* One or both arg must be an infinity */
  else if ( st0_tag == TW_Infinity )
    {
      if ( (signnegative(st0_ptr)) || (st1_tag == TAG_Zero) )
	{
	  /* log(-infinity) or 0*log(infinity) */
	  if ( arith_invalid(1) < 0 )
	    return;
	}
      else
	{
	  u_char sign = getsign(st1_ptr);

	  if ( (st1_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;

	  FPU_copy_to_reg1(&CONST_INF, TAG_Special);
	  setsign(st1_ptr, sign);
	}
    }
  /* st(1) must be infinity here */
  else if ( ((st0_tag == TAG_Valid) || (st0_tag == TW_Denormal))
	    && ( signpositive(st0_ptr) ) )
    {
      if ( exponent(st0_ptr) >= 0 )
	{
	  if ( (exponent(st0_ptr) == 0) &&
	      (st0_ptr->sigh == 0x80000000) &&
	      (st0_ptr->sigl == 0) )
	    {
	      /* st(0) holds 1.0 */
	      /* infinity*log(1) */
	      if ( arith_invalid(1) < 0 )
		return;
	    }
	  /* else st(0) is positive and > 1.0 */
	}
      else
	{
	  /* st(0) is positive and < 1.0 */

	  if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;

	  changesign(st1_ptr);
	}
    }
  else
    {
      /* st(0) must be zero or negative */
      if ( st0_tag == TAG_Zero )
	{
	  /* This should be invalid, but a real 80486 is happy with it. */

#ifndef PECULIAR_486
	  sign = getsign(st1_ptr);
	  if ( FPU_divide_by_zero(1, sign) < 0 )
	    return;
#endif /* PECULIAR_486 */

	  changesign(st1_ptr);
	}
      else if ( arith_invalid(1) < 0 )	  /* log(negative) */
	return;
    }

  FPU_pop();
}


static void fpatan(FPU_REG *st0_ptr, u_char st0_tag)
{
  FPU_REG *st1_ptr = &st(1);
  u_char st1_tag = FPU_gettagi(1);
  int tag;

  clear_C1();
  if ( !((st0_tag ^ TAG_Valid) | (st1_tag ^ TAG_Valid)) )
    {
    valid_atan:

      poly_atan(st0_ptr, st0_tag, st1_ptr, st1_tag);

      FPU_pop();

      return;
    }

  if ( st0_tag == TAG_Special )
    st0_tag = FPU_Special(st0_ptr);
  if ( st1_tag == TAG_Special )
    st1_tag = FPU_Special(st1_ptr);

  if ( ((st0_tag == TAG_Valid) && (st1_tag == TW_Denormal))
	    || ((st0_tag == TW_Denormal) && (st1_tag == TAG_Valid))
	    || ((st0_tag == TW_Denormal) && (st1_tag == TW_Denormal)) )
    {
      if ( denormal_operand() < 0 )
	return;

      goto valid_atan;
    }
  else if ( (st0_tag == TAG_Empty) || (st1_tag == TAG_Empty) )
    {
      FPU_stack_underflow_pop(1);
      return;
    }
  else if ( (st0_tag == TW_NaN) || (st1_tag == TW_NaN) )
    {
      if ( real_2op_NaN(st0_ptr, st0_tag, 1, st0_ptr) >= 0 )
	  FPU_pop();
      return;
    }
  else if ( (st0_tag == TW_Infinity) || (st1_tag == TW_Infinity) )
    {
      u_char sign = getsign(st1_ptr);
      if ( st0_tag == TW_Infinity )
	{
	  if ( st1_tag == TW_Infinity )
	    {
	      if ( signpositive(st0_ptr) )
		{
		  FPU_copy_to_reg1(&CONST_PI4, TAG_Valid);
		}
	      else
		{
		  setpositive(st1_ptr);
		  tag = FPU_u_add(&CONST_PI4, &CONST_PI2, st1_ptr,
				  FULL_PRECISION, SIGN_POS,
				  exponent(&CONST_PI4), exponent(&CONST_PI2));
		  if ( tag >= 0 )
		    FPU_settagi(1, tag);
		}
	    }
	  else
	    {
	      if ( (st1_tag == TW_Denormal) && (denormal_operand() < 0) )
		return;

	      if ( signpositive(st0_ptr) )
		{
		  FPU_copy_to_reg1(&CONST_Z, TAG_Zero);
		  setsign(st1_ptr, sign);   /* An 80486 preserves the sign */
		  FPU_pop();
		  return;
		}
	      else
		{
		  FPU_copy_to_reg1(&CONST_PI, TAG_Valid);
		}
	    }
	}
      else
	{
	  /* st(1) is infinity, st(0) not infinity */
	  if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;

	  FPU_copy_to_reg1(&CONST_PI2, TAG_Valid);
	}
      setsign(st1_ptr, sign);
    }
  else if ( st1_tag == TAG_Zero )
    {
      /* st(0) must be valid or zero */
      u_char sign = getsign(st1_ptr);

      if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	return;

      if ( signpositive(st0_ptr) )
	{
	  /* An 80486 preserves the sign */
	  FPU_pop();
	  return;
	}

      FPU_copy_to_reg1(&CONST_PI, TAG_Valid);
      setsign(st1_ptr, sign);
    }
  else if ( st0_tag == TAG_Zero )
    {
      /* st(1) must be TAG_Valid here */
      u_char sign = getsign(st1_ptr);

      if ( (st1_tag == TW_Denormal) && (denormal_operand() < 0) )
	return;

      FPU_copy_to_reg1(&CONST_PI2, TAG_Valid);
      setsign(st1_ptr, sign);
    }
#ifdef PARANOID
  else
    EXCEPTION(EX_INTERNAL | 0x125);
#endif /* PARANOID */

  FPU_pop();
  set_precision_flag_up();  /* We do not really know if up or down */
}


static void fprem(FPU_REG *st0_ptr, u_char st0_tag)
{
  do_fprem(st0_ptr, st0_tag, RC_CHOP);
}


static void fprem1(FPU_REG *st0_ptr, u_char st0_tag)
{
  do_fprem(st0_ptr, st0_tag, RC_RND);
}


static void fyl2xp1(FPU_REG *st0_ptr, u_char st0_tag)
{
  u_char sign, sign1;
  FPU_REG *st1_ptr = &st(1), a, b;
  u_char st1_tag = FPU_gettagi(1);

  clear_C1();
  if ( !((st0_tag ^ TAG_Valid) | (st1_tag ^ TAG_Valid)) )
    {
    valid_yl2xp1:

      sign = getsign(st0_ptr);
      sign1 = getsign(st1_ptr);

      FPU_to_exp16(st0_ptr, &a);
      FPU_to_exp16(st1_ptr, &b);

      if ( poly_l2p1(sign, sign1, &a, &b, st1_ptr) )
	return;

      FPU_pop();
      return;
    }

  if ( st0_tag == TAG_Special )
    st0_tag = FPU_Special(st0_ptr);
  if ( st1_tag == TAG_Special )
    st1_tag = FPU_Special(st1_ptr);

  if ( ((st0_tag == TAG_Valid) && (st1_tag == TW_Denormal))
	    || ((st0_tag == TW_Denormal) && (st1_tag == TAG_Valid))
	    || ((st0_tag == TW_Denormal) && (st1_tag == TW_Denormal)) )
    {
      if ( denormal_operand() < 0 )
	return;

      goto valid_yl2xp1;
    }
  else if ( (st0_tag == TAG_Empty) | (st1_tag == TAG_Empty) )
    {
      FPU_stack_underflow_pop(1);
      return;
    }
  else if ( st0_tag == TAG_Zero )
    {
      switch ( st1_tag )
	{
	case TW_Denormal:
	  if ( denormal_operand() < 0 )
	    return;

	case TAG_Zero:
	case TAG_Valid:
	  setsign(st0_ptr, getsign(st0_ptr) ^ getsign(st1_ptr));
	  FPU_copy_to_reg1(st0_ptr, st0_tag);
	  break;

	case TW_Infinity:
	  /* Infinity*log(1) */
	  if ( arith_invalid(1) < 0 )
	    return;
	  break;

	case TW_NaN:
	  if ( real_2op_NaN(st0_ptr, st0_tag, 1, st0_ptr) < 0 )
	    return;
	  break;

	default:
#ifdef PARANOID
	  EXCEPTION(EX_INTERNAL | 0x116);
	  return;
#endif /* PARANOID */
	  break;
	}
    }
  else if ( (st0_tag == TAG_Valid) || (st0_tag == TW_Denormal) )
    {
      switch ( st1_tag )
	{
	case TAG_Zero:
	  if ( signnegative(st0_ptr) )
	    {
	      if ( exponent(st0_ptr) >= 0 )
		{
		  /* st(0) holds <= -1.0 */
#ifdef PECULIAR_486   /* Stupid 80486 doesn't worry about log(negative). */
		  changesign(st1_ptr);
#else
		  if ( arith_invalid(1) < 0 )
		    return;
#endif /* PECULIAR_486 */
		}
	      else if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
		return;
	      else
		changesign(st1_ptr);
	    }
	  else if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;
	  break;

	case TW_Infinity:
	  if ( signnegative(st0_ptr) )
	    {
	      if ( (exponent(st0_ptr) >= 0) &&
		  !((st0_ptr->sigh == 0x80000000) &&
		    (st0_ptr->sigl == 0)) )
		{
		  /* st(0) holds < -1.0 */
#ifdef PECULIAR_486   /* Stupid 80486 doesn't worry about log(negative). */
		  changesign(st1_ptr);
#else
		  if ( arith_invalid(1) < 0 ) return;
#endif /* PECULIAR_486 */
		}
	      else if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
		return;
	      else
		changesign(st1_ptr);
	    }
	  else if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;
	  break;

	case TW_NaN:
	  if ( real_2op_NaN(st0_ptr, st0_tag, 1, st0_ptr) < 0 )
	    return;
	}

    }
  else if ( st0_tag == TW_NaN )
    {
      if ( real_2op_NaN(st0_ptr, st0_tag, 1, st0_ptr) < 0 )
	return;
    }
  else if ( st0_tag == TW_Infinity )
    {
      if ( st1_tag == TW_NaN )
	{
	  if ( real_2op_NaN(st0_ptr, st0_tag, 1, st0_ptr) < 0 )
	    return;
	}
      else if ( signnegative(st0_ptr) )
	{
#ifndef PECULIAR_486
	  /* This should have higher priority than denormals, but... */
	  if ( arith_invalid(1) < 0 )  /* log(-infinity) */
	    return;
#endif /* PECULIAR_486 */
	  if ( (st1_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;
#ifdef PECULIAR_486
	  /* Denormal operands actually get higher priority */
	  if ( arith_invalid(1) < 0 )  /* log(-infinity) */
	    return;
#endif /* PECULIAR_486 */
	}
      else if ( st1_tag == TAG_Zero )
	{
	  /* log(infinity) */
	  if ( arith_invalid(1) < 0 )
	    return;
	}
	
      /* st(1) must be valid here. */

      else if ( (st1_tag == TW_Denormal) && (denormal_operand() < 0) )
	return;

      /* The Manual says that log(Infinity) is invalid, but a real
	 80486 sensibly says that it is o.k. */
      else
	{
	  u_char sign = getsign(st1_ptr);
	  FPU_copy_to_reg1(&CONST_INF, TAG_Special);
	  setsign(st1_ptr, sign);
	}
    }
#ifdef PARANOID
  else
    {
      EXCEPTION(EX_INTERNAL | 0x117);
      return;
    }
#endif /* PARANOID */

  FPU_pop();
  return;

}


static void fscale(FPU_REG *st0_ptr, u_char st0_tag)
{
  FPU_REG *st1_ptr = &st(1);
  u_char st1_tag = FPU_gettagi(1);
  int old_cw = control_word;
  u_char sign = getsign(st0_ptr);

  clear_C1();
  if ( !((st0_tag ^ TAG_Valid) | (st1_tag ^ TAG_Valid)) )
    {
      long scale;
      FPU_REG tmp;

      /* Convert register for internal use. */
      setexponent16(st0_ptr, exponent(st0_ptr));

    valid_scale:

      if ( exponent(st1_ptr) > 30 )
	{
	  /* 2^31 is far too large, would require 2^(2^30) or 2^(-2^30) */

	  if ( signpositive(st1_ptr) )
	    {
	      EXCEPTION(EX_Overflow);
	      FPU_copy_to_reg0(&CONST_INF, TAG_Special);
	    }
	  else
	    {
	      EXCEPTION(EX_Underflow);
	      FPU_copy_to_reg0(&CONST_Z, TAG_Zero);
	    }
	  setsign(st0_ptr, sign);
	  return;
	}

      control_word &= ~CW_RC;
      control_word |= RC_CHOP;
      reg_copy(st1_ptr, &tmp);
      FPU_round_to_int(&tmp, st1_tag);      /* This can never overflow here */
      control_word = old_cw;
      scale = signnegative(st1_ptr) ? -tmp.sigl : tmp.sigl;
      scale += exponent16(st0_ptr);

      setexponent16(st0_ptr, scale);

      /* Use FPU_round() to properly detect under/overflow etc */
      FPU_round(st0_ptr, 0, 0, control_word, sign);

      return;
    }

  if ( st0_tag == TAG_Special )
    st0_tag = FPU_Special(st0_ptr);
  if ( st1_tag == TAG_Special )
    st1_tag = FPU_Special(st1_ptr);

  if ( (st0_tag == TAG_Valid) || (st0_tag == TW_Denormal) )
    {
      switch ( st1_tag )
	{
	case TAG_Valid:
	  /* st(0) must be a denormal */
	  if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;

	  FPU_to_exp16(st0_ptr, st0_ptr);  /* Will not be left on stack */
	  goto valid_scale;

	case TAG_Zero:
	  if ( st0_tag == TW_Denormal )
	    denormal_operand();
	  return;

	case TW_Denormal:
	  denormal_operand();
	  return;

	case TW_Infinity:
	  if ( (st0_tag == TW_Denormal) && (denormal_operand() < 0) )
	    return;

	  if ( signpositive(st1_ptr) )
	    FPU_copy_to_reg0(&CONST_INF, TAG_Special);
	  else
	    FPU_copy_to_reg0(&CONST_Z, TAG_Zero);
	  setsign(st0_ptr, sign);
	  return;

	case TW_NaN:
	  real_2op_NaN(st1_ptr, st1_tag, 0, st0_ptr);
	  return;
	}
    }
  else if ( st0_tag == TAG_Zero )
    {
      switch ( st1_tag )
	{
	case TAG_Valid:
	case TAG_Zero:
	  return;

	case TW_Denormal:
	  denormal_operand();
	  return;

	case TW_Infinity:
	  if ( signpositive(st1_ptr) )
	    arith_invalid(0); /* Zero scaled by +Infinity */
	  return;

	case TW_NaN:
	  real_2op_NaN(st1_ptr, st1_tag, 0, st0_ptr);
	  return;
	}
    }
  else if ( st0_tag == TW_Infinity )
    {
      switch ( st1_tag )
	{
	case TAG_Valid:
	case TAG_Zero:
	  return;

	case TW_Denormal:
	  denormal_operand();
	  return;

	case TW_Infinity:
	  if ( signnegative(st1_ptr) )
	    arith_invalid(0); /* Infinity scaled by -Infinity */
	  return;

	case TW_NaN:
	  real_2op_NaN(st1_ptr, st1_tag, 0, st0_ptr);
	  return;
	}
    }
  else if ( st0_tag == TW_NaN )
    {
      if ( st1_tag != TAG_Empty )
	{ real_2op_NaN(st1_ptr, st1_tag, 0, st0_ptr); return; }
    }

#ifdef PARANOID
  if ( !((st0_tag == TAG_Empty) || (st1_tag == TAG_Empty)) )
    {
      EXCEPTION(EX_INTERNAL | 0x115);
      return;
    }
#endif

  /* At least one of st(0), st(1) must be empty */
  FPU_stack_underflow();

}


/*---------------------------------------------------------------------------*/

static FUNC_ST0 const trig_table_a[] = {
  f2xm1, fyl2x, fptan, fpatan,
  fxtract, fprem1, (FUNC_ST0)fdecstp, (FUNC_ST0)fincstp
};

void FPU_triga(void)
{
  (trig_table_a[FPU_rm])(&st(0), FPU_gettag0());
}


static FUNC_ST0 const trig_table_b[] =
  {
    fprem, fyl2xp1, fsqrt_, fsincos, frndint_, fscale, (FUNC_ST0)fsin, fcos
  };

void FPU_trigb(void)
{
  (trig_table_b[FPU_rm])(&st(0), FPU_gettag0());
}