1  /* Copyright (C) 2012-2023 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     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <math.h>
      19  #include <math_private.h>
      20  #include <float.h>
      21  #include <libm-alias-finite.h>
      22  
      23  static const double log10_high = 0x2.4d7637p0;
      24  static const double log10_low = 0x7.6aaa2b05ba95cp-28;
      25  
      26  double
      27  __ieee754_exp10 (double arg)
      28  {
      29    int32_t lx;
      30    double arg_high, arg_low;
      31    double exp_high, exp_low;
      32  
      33    if (!isfinite (arg))
      34      return __ieee754_exp (arg);
      35    if (arg < DBL_MIN_10_EXP - DBL_DIG - 10)
      36      return DBL_MIN * DBL_MIN;
      37    else if (arg > DBL_MAX_10_EXP + 1)
      38      return DBL_MAX * DBL_MAX;
      39    else if (fabs (arg) < 0x1p-56)
      40      return 1.0;
      41  
      42    GET_LOW_WORD (lx, arg);
      43    lx &= 0xf8000000;
      44    arg_high = arg;
      45    SET_LOW_WORD (arg_high, lx);
      46    arg_low = arg - arg_high;
      47    exp_high = arg_high * log10_high;
      48    exp_low = arg_high * log10_low + arg_low * M_LN10;
      49    return __ieee754_exp (exp_high) * __ieee754_exp (exp_low);
      50  }
      51  libm_alias_finite (__ieee754_exp10, __exp10)