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73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
/* Round double to integer away from zero.
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Copyright (C) 1997-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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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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#define NO_MATH_REDIRECT
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#include <math.h>
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#include <math_private.h>
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#include <libm-alias-double.h>
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#include <stdint.h>
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#include <math-use-builtins.h>
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double
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__round (double x)
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{
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#if USE_ROUND_BUILTIN
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return __builtin_round (x);
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#else
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/* Use generic implementation. */
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int64_t i0, j0;
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EXTRACT_WORDS64 (i0, x);
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j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
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if (__glibc_likely (j0 < 52))
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{
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if (j0 < 0)
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{
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i0 &= UINT64_C (0x8000000000000000);
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if (j0 == -1)
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i0 |= UINT64_C (0x3ff0000000000000);
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}
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else
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{
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uint64_t i = UINT64_C (0x000fffffffffffff) >> j0;
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if ((i0 & i) == 0)
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/* X is integral. */
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return x;
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i0 += UINT64_C (0x0008000000000000) >> j0;
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i0 &= ~i;
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}
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}
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else
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{
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if (j0 == 0x400)
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/* Inf or NaN. */
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return x + x;
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else
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return x;
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}
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INSERT_WORDS64 (x, i0);
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return x;
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#endif /* ! USE_ROUND_BUILTIN */
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}
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libm_alias_double (__round, round)
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