| /* Compute 2^x. |
| Copyright (C) 2012-2018 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> |
| |
| #define declare_mgen_finite_alias_x(from, to) \ |
| strong_alias (from, to ## _finite) |
| #define declare_mgen_finite_alias_s(from,to) \ |
| declare_mgen_finite_alias_x (from, to) |
| #define declare_mgen_finite_alias(from, to) \ |
| declare_mgen_finite_alias_s (M_SUF (from), M_SUF (to)) |
| |
| FLOAT |
| M_DECL_FUNC (__ieee754_exp2) (FLOAT x) |
| { |
| if (__glibc_likely (isless (x, (FLOAT) M_MAX_EXP))) |
| { |
| if (__builtin_expect (isgreaterequal (x, (FLOAT) (M_MIN_EXP - M_MANT_DIG |
| - 1)), 1)) |
| { |
| int intx = (int) x; |
| FLOAT fractx = x - intx; |
| FLOAT result; |
| if (M_FABS (fractx) < M_EPSILON / 4) |
| result = M_SCALBN (1 + fractx, intx); |
| else |
| result = M_SCALBN (M_EXP (M_SUF (M_LN2) * fractx), intx); |
| math_check_force_underflow_nonneg (result); |
| return result; |
| } |
| else |
| { |
| /* Underflow or exact zero. */ |
| if (isinf (x)) |
| return 0; |
| else |
| return M_MIN * M_MIN; |
| } |
| } |
| else |
| /* Infinity, NaN or overflow. */ |
| return M_MAX * x; |
| } |
| declare_mgen_finite_alias (__ieee754_exp2, __exp2) |
