math/w_scalb.c

   1 /* Copyright (C) 2011 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    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <math.h>
  21 #include <math_private.h>
  22
  23
  24 static double
  25 __attribute__ ((noinline))
  26 sysv_scalb (double x, double fn)
  27 {
  28   double z = __ieee754_scalb (x, fn);
  29
  30   if (__builtin_expect (__isinf (z), 0))
  31     {
  32       if (__finite (x))
  33         return __kernel_standard (x, fn, 32); /* scalb overflow */
  34       else
  35         __set_errno (ERANGE);
  36     }
  37   else if (__builtin_expect (z == 0.0, 0) && z != x)
  38     return __kernel_standard (x, fn, 33); /* scalb underflow */
  39
  40   return z;
  41 }
  42
  43
  44 /* Wrapper scalb */
  45 double
  46 __scalb (double x, double fn)
  47 {
  48   return (__builtin_expect (_LIB_VERSION == _SVID_, 0)
  49           ? sysv_scalb (x, fn)
  50           : __ieee754_scalb (x, fn));
  51 }
  52 weak_alias (__scalb, scalb)
  53 #ifdef NO_LONG_DOUBLE
  54 strong_alias (__scalb, __scalbl)
  55 weak_alias (__scalb, scalbl)
  56 #endif