sysdeps/alpha/fpu/s_ceilf.c

   1 /* Copyright (C) 1998-2015 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 /* Use the -inf rounding mode conversion instructions to implement
  22    ceil, via something akin to -floor(-x).  This is much faster than
  23    playing with the fpcr to achieve +inf rounding mode.  */
  24
  25 float
  26 __ceilf (float x)
  27 {
  28   if (isless (fabsf (x), 16777216.0f))  /* 1 << FLT_MANT_DIG */
  29     {
  30       /* Note that Alpha S_Floating is stored in registers in a
  31          restricted T_Floating format, so we don't even need to
  32          convert back to S_Floating in the end.  The initial
  33          conversion to T_Floating is needed to handle denormals.  */
  34
  35       float tmp1, tmp2, new_x;
  36
  37       new_x = -x;
  38       __asm ("cvtst/s %3,%2\n\t"
  39 #ifdef _IEEE_FP_INEXACT
  40              "cvttq/svim %2,%1\n\t"
  41 #else
  42              "cvttq/svm %2,%1\n\t"
  43 #endif
  44              "cvtqt/m %1,%0\n\t"
  45              : "=f"(new_x), "=&f"(tmp1), "=&f"(tmp2)
  46              : "f"(new_x));
  47
  48       /* Fix up the negation we did above, as well as handling -0 properly. */
  49       x = copysignf(new_x, x);
  50     }
  51   return x;
  52 }
  53
  54 weak_alias (__ceilf, ceilf)