sysdeps/alpha/fpu/s_truncf.c

   1 /* Copyright (C) 2007-2015 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
  21
  22 /* Use the chopped rounding mode conversion instructions to implement trunc. */
  23
  24 float
  25 __truncf (float x)
  26 {
  27   float two23 = copysignf (0x1.0p23, x);
  28   float r, tmp;
  29
  30   __asm (
  31 #ifdef _IEEE_FP_INEXACT
  32          "adds/suic %2, %3, %1\n\tsubs/suic %1, %3, %0"
  33 #else
  34          "adds/suc %2, %3, %1\n\tsubs/suc %1, %3, %0"
  35 #endif
  36          : "=&f"(r), "=&f"(tmp)
  37          : "f"(x), "f"(two23));
  38
  39   /* trunc(-0) == -0, and in general we'll always have the same
  40      sign as our input.  */
  41   return copysignf (r, x);
  42 }
  43
  44 weak_alias (__truncf, truncf)