sysdeps/alpha/fpu/s_ceilf.c

   1 /* Copyright (C) 1998, 2000, 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
  22 /* Use the -inf rounding mode conversion instructions to implement
  23    ceil, via something akin to -floor(-x).  This is much faster than
  24    playing with the fpcr to achieve +inf rounding mode.  */
  25
  26 float
  27 __ceilf (float x)
  28 {
  29   float two23 = copysignf (0x1.0p23, x);
  30   float r, tmp;
  31
  32   __asm (
  33 #ifdef _IEEE_FP_INEXACT
  34          "adds/suim %2, %3, %1\n\tsubs/suim %1, %3, %0"
  35 #else
  36          "adds/sum %2, %3, %1\n\tsubs/sum %1, %3, %0"
  37 #endif
  38          : "=&f"(r), "=&f"(tmp)
  39          : "f"(-x), "f"(-two23));
  40
  41   /* Fix up the negation we did above, as well as handling -0 properly. */
  42   return copysignf (r, x);
  43 }
  44
  45 weak_alias (__ceilf, ceilf)