ports/sysdeps/alpha/fpu/s_round.c

   1 /* Copyright (C) 2007-2014 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    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <math.h>
  19 #include <math_ldbl_opt.h>
  20
  21
  22 double
  23 __round (double x)
  24 {
  25   const double almost_half = 0x1.fffffffffffffp-2;
  26   const double two52 = 0x1.0p52;
  27   double tmp, r;
  28
  29   __asm (
  30 #ifdef _IEEE_FP_INEXACT
  31          "addt/suic %2, %3, %1\n\tsubt/suic %1, %3, %0"
  32 #else
  33          "addt/suc %2, %3, %1\n\tsubt/suc %1, %3, %0"
  34 #endif
  35          : "=&f"(r), "=&f"(tmp)
  36          : "f"(fabs (x) + almost_half), "f"(two52));
  37
  38   return copysign (r, x);
  39 }
  40
  41 weak_alias (__round, round)
  42 #ifdef NO_LONG_DOUBLE
  43 strong_alias (__round, __roundl)
  44 weak_alias (__roundl, roundl)
  45 #endif
  46 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_1)
  47 compat_symbol (libm, __round, roundl, GLIBC_2_1);
  48 #endif