sysdeps/alpha/fpu/s_nearbyint.c

   1 /* Copyright (C) 2007 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Richard Henderson.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <math.h>
  21 #include <math_ldbl_opt.h>
  22
  23 #ifdef _IEEE_FP_INEXACT
  24 #error "Don't compile with -mieee-with-inexact"
  25 #endif
  26
  27 double
  28 __nearbyint (double x)
  29 {
  30   double two52 = copysign (0x1.0p52, x);
  31   double r;
  32
  33   r = x + two52;
  34   r = r - two52;
  35
  36   /* nearbyint(-0.1) == -0, and in general we'll always have the same sign
  37      as our input.  */
  38   return copysign (r, x);
  39 }
  40
  41 weak_alias (__nearbyint, nearbyint)
  42 #ifdef NO_LONG_DOUBLE
  43 strong_alias (__nearbyint, __nearbyintl)
  44 weak_alias (__nearbyint, nearbyintl)
  45 #endif
  46 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
  47 compat_symbol (libm, __nearbyint, nearbyintl, GLIBC_2_1);
  48 #endif