1/* Compute 2^x. 2 Copyright (C) 2012-2018 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <http://www.gnu.org/licenses/>. */ 18 19#include "quadmath-imp.h" 20 21__float128 22exp2q (__float128 x) 23{ 24 if (__glibc_likely (__builtin_isless (x, (__float128) FLT128_MAX_EXP))) 25 { 26 if (__builtin_expect (__builtin_isgreaterequal (x, (__float128) (FLT128_MIN_EXP - FLT128_MANT_DIG 27 - 1)), 1)) 28 { 29 int intx = (int) x; 30 __float128 fractx = x - intx; 31 __float128 result; 32 if (fabsq (fractx) < FLT128_EPSILON / 4) 33 result = scalbnq (1 + fractx, intx); 34 else 35 result = scalbnq (expq (M_LN2q * fractx), intx); 36 math_check_force_underflow_nonneg (result); 37 return result; 38 } 39 else 40 { 41 /* Underflow or exact zero. */ 42 if (isinfq (x)) 43 return 0; 44 else 45 return FLT128_MIN * FLT128_MIN; 46 } 47 } 48 else 49 /* Infinity, NaN or overflow. */ 50 return FLT128_MAX * x; 51} 52