Blame sysdeps/ieee754/ldbl-128ibm/s_roundl.c

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/* Round to int long double floating-point values.
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   IBM extended format long double version.
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   Copyright (C) 2006-2018 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <http://www.gnu.org/licenses/>.  */
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/* This has been coded in assembler because GCC makes such a mess of it
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   when it's coded in C.  */
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#include <math.h>
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#include <math_private.h>
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#include <math_ldbl_opt.h>
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#include <float.h>
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#include <ieee754.h>
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long double
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__roundl (long double x)
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{
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  double xh, xl, hi, lo;
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  ldbl_unpack (x, &xh, &xl);
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  /* Return Inf, Nan, +/-0 unchanged.  */
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  if (__builtin_expect (xh != 0.0
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			&& __builtin_isless (__builtin_fabs (xh),
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					     __builtin_inf ()), 1))
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    {
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      hi = __round (xh);
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      if (hi != xh)
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	{
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	  /* The high part is not an integer; the low part only
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	     affects the result if the high part is exactly half way
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	     between two integers and the low part is nonzero with the
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	     opposite sign.  */
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	  if (fabs (hi - xh) == 0.5)
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	    {
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	      if (xh > 0 && xl < 0)
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		xh = hi - 1;
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	      else if (xh < 0 && xl > 0)
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		xh = hi + 1;
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	      else
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		xh = hi;
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	    }
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	  else
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	    xh = hi;
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	  xl = 0;
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	}
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      else
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	{
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	  /* The high part is a nonzero integer.  */
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	  lo = __round (xl);
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	  if (fabs (lo - xl) == 0.5)
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	    {
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	      if (xh > 0 && xl < 0)
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		xl = lo + 1;
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	      else if (xh < 0 && lo > 0)
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		xl = lo - 1;
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	      else
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		xl = lo;
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	    }
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	  else
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	    xl = lo;
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	  xh = hi;
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	  ldbl_canonicalize_int (&xh, &xl);
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	}
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    }
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  else
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    /* Quiet signaling NaN arguments.  */
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    xh += xh;
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  return ldbl_pack (xh, xl);
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}
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long_double_symbol (libm, __roundl, roundl);