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71 lines
2.0 KiB
C
71 lines
2.0 KiB
C
/* Round to nearest integer value, rounding halfway cases to even.
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ldbl-128ibm version.
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Copyright (C) 2016-2020 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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<https://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_private.h>
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long double
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__roundevenl (long double x)
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{
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double xh, xl, hi;
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ldbl_unpack (x, &xh, &xl);
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if (xh != 0 && isfinite (xh))
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{
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hi = __roundeven (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 in the
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opposite direction to the rounding of the high part. */
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double diff = hi - xh;
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if (fabs (diff) == 0.5)
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{
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if (xl < 0 && diff > 0)
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xh = hi - 1;
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else if (xl > 0 && diff < 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. Rounding the low
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part to nearest, ties round to even, is always correct,
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as a high part that is an odd integer together with a low
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part with magnitude 0.5 is not a valid long double. */
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xl = __roundeven (xl);
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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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weak_alias (__roundevenl, roundevenl)
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