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/* Round to nearest integer value, rounding halfway cases to even.
ldbl-128ibm version.
Copyright (C) 2016-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <math.h>
#include <math_private.h>
long double
roundevenl (long double x)
{
double xh, xl, hi;
ldbl_unpack (x, &xh, &xl);
if (xh != 0 && isfinite (xh))
{
hi = roundeven (xh);
if (hi != xh)
{
/* The high part is not an integer; the low part only
affects the result if the high part is exactly half way
between two integers and the low part is nonzero in the
opposite direction to the rounding of the high part. */
double diff = hi - xh;
if (fabs (diff) == 0.5)
{
if (xl < 0 && diff > 0)
xh = hi - 1;
else if (xl > 0 && diff < 0)
xh = hi + 1;
else
xh = hi;
}
else
xh = hi;
xl = 0;
}
else
{
/* The high part is a nonzero integer. Rounding the low
part to nearest, ties round to even, is always correct,
as a high part that is an odd integer together with a low
part with magnitude 0.5 is not a valid long double. */
xl = roundeven (xl);
xh = hi;
ldbl_canonicalize_int (&xh, &xl);
}
}
else
/* Quiet signaling NaN arguments. */
xh += xh;
return ldbl_pack (xh, xl);
}
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