sysdeps/alpha/fpu/s_nearbyint.c

   1 /* Copyright (C) 2000-2012 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <math.h>
  20 #include <math_ldbl_opt.h>
  21
  22
  23 double
  24 __nearbyint (double x)
  25 {
  26   if (isless (fabs (x), 9007199254740992.0))    /* 1 << DBL_MANT_DIG */
  27     {
  28       double tmp1, new_x;
  29       __asm ("cvttq/svd %2,%1\n\t"
  30              "cvtqt/d %1,%0\n\t"
  31              : "=f"(new_x), "=&f"(tmp1)
  32              : "f"(x));
  33
  34       /* nearbyint(-0.1) == -0, and in general we'll always have the same
  35          sign as our input.  */
  36       x = copysign(new_x, x);
  37     }
  38   return 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_0)
  47 compat_symbol (libm, __nearbyint, nearbyintl, GLIBC_2_0);
  48 #endif