math/w_log2_compat.c

   1 /* Copyright (C) 2011-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
   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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <fenv.h>
  20 #include <math.h>
  21 #include <math_private.h>
  22 #include <math-svid-compat.h>
  23 #include <libm-alias-double.h>
  24
  25
  26 #if LIBM_SVID_COMPAT && (SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_29) \
  27                          || defined NO_LONG_DOUBLE \
  28                          || defined LONG_DOUBLE_COMPAT)
  29 /* wrapper log2(x) */
  30 double
  31 __log2_compat (double x)
  32 {
  33   if (__builtin_expect (islessequal (x, 0.0), 0) && _LIB_VERSION != _IEEE_)
  34     {
  35       if (x == 0.0)
  36         {
  37           feraiseexcept (FE_DIVBYZERO);
  38           return __kernel_standard (x, x, 48); /* log2(0) */
  39         }
  40       else
  41         {
  42           feraiseexcept (FE_INVALID);
  43           return __kernel_standard (x, x, 49); /* log2(x<0) */
  44         }
  45     }
  46
  47   return  __ieee754_log2 (x);
  48 }
  49 # if SHLIB_COMPAT (libm, GLIBC_2_1, GLIBC_2_29)
  50 compat_symbol (libm, __log2_compat, log2, GLIBC_2_1);
  51 # endif
  52 # ifdef NO_LONG_DOUBLE
  53 weak_alias (__log2_compat, log2l)
  54 # endif
  55 # ifdef LONG_DOUBLE_COMPAT
  56 /* Work around gas bug "multiple versions for symbol".  */
  57 weak_alias (__log2_compat, __log2_compat_alias)
  58
  59 LONG_DOUBLE_COMPAT_CHOOSE_libm_log2l (
  60   compat_symbol (libm, __log2_compat_alias, log2l, FIRST_VERSION_libm_log2l), );
  61 # endif
  62 #endif