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52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
/* Compute 2^x.
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Copyright (C) 2012-2018 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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#include "quadmath-imp.h"
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__float128
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exp2q (__float128 x)
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{
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if (__glibc_likely (__builtin_isless (x, (__float128) FLT128_MAX_EXP)))
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{
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if (__builtin_expect (__builtin_isgreaterequal (x, (__float128) (FLT128_MIN_EXP - FLT128_MANT_DIG
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- 1)), 1))
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{
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int intx = (int) x;
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__float128 fractx = x - intx;
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__float128 result;
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if (fabsq (fractx) < FLT128_EPSILON / 4)
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result = scalbnq (1 + fractx, intx);
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else
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result = scalbnq (expq (M_LN2q * fractx), intx);
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math_check_force_underflow_nonneg (result);
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return result;
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}
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else
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{
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/* Underflow or exact zero. */
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if (isinfq (x))
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return 0;
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else
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return FLT128_MIN * FLT128_MIN;
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}
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}
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else
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/* Infinity, NaN or overflow. */
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return FLT128_MAX * x;
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}
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