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