| /* Compute 2^x. |
| Copyright (C) 2012-2016 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> |
| #include <float.h> |
| |
| /* To avoid spurious underflows, use this definition to treat IBM long |
| double as approximating an IEEE-style format. */ |
| #if LDBL_MANT_DIG == 106 |
| # undef LDBL_EPSILON |
| # define LDBL_EPSILON 0x1p-106L |
| #endif |
| |
| long double |
| __ieee754_exp2l (long double x) |
| { |
| if (__glibc_likely (isless (x, (long double) LDBL_MAX_EXP))) |
| { |
| if (__builtin_expect (isgreaterequal (x, (long double) (LDBL_MIN_EXP |
| - LDBL_MANT_DIG |
| - 1)), 1)) |
| { |
| int intx = (int) x; |
| long double fractx = x - intx; |
| long double result; |
| if (fabsl (fractx) < LDBL_EPSILON / 4.0L) |
| result = __scalbnl (1.0L + fractx, intx); |
| else |
| result = __scalbnl (__ieee754_expl (M_LN2l * fractx), intx); |
| math_check_force_underflow_nonneg (result); |
| return result; |
| } |
| else |
| { |
| /* Underflow or exact zero. */ |
| if (isinf (x)) |
| return 0; |
| else |
| return LDBL_MIN * LDBL_MIN; |
| } |
| } |
| else |
| /* Infinity, NaN or overflow. */ |
| return LDBL_MAX * x; |
| } |
| strong_alias (__ieee754_exp2l, __exp2l_finite) |