sysdeps/ieee754/ldbl-128ibm/e_exp10l.c

   1 /* Copyright (C) 2012-2015 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <math.h>
  19 #include <math_private.h>
  20 #include <float.h>
  21
  22 static const long double log10_high = 0x2.4d763776aaap+0L;
  23 static const long double log10_low = 0x2.b05ba95b58ae0b4c28a38a3fb4p-48L;
  24
  25 long double
  26 __ieee754_exp10l (long double arg)
  27 {
  28   union ibm_extended_long_double u;
  29   long double arg_high, arg_low;
  30   long double exp_high, exp_low;
  31
  32   if (!isfinite (arg))
  33     return __ieee754_expl (arg);
  34   if (arg < LDBL_MIN_10_EXP - LDBL_DIG - 10)
  35     return LDBL_MIN * LDBL_MIN;
  36   else if (arg > LDBL_MAX_10_EXP + 1)
  37     return LDBL_MAX * LDBL_MAX;
  38   else if (fabsl (arg) < 0x1p-109L)
  39     return 1.0L;
  40
  41   u.ld = arg;
  42   arg_high = u.d[0].d;
  43   arg_low = u.d[1].d;
  44   exp_high = arg_high * log10_high;
  45   exp_low = arg_high * log10_low + arg_low * M_LN10l;
  46   return __ieee754_expl (exp_high) * __ieee754_expl (exp_low);
  47 }
  48 strong_alias (__ieee754_exp10l, __exp10l_finite)