sysdeps/alpha/fpu/s_ceil.c

   1 /* Copyright (C) 1998, 2000, 2006, 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 #include <math_ldbl_opt.h>
  22
  23 /* Use the -inf rounding mode conversion instructions to implement
  24    ceil, via something akin to -floor(-x).  This is much faster than
  25    playing with the fpcr to achieve +inf rounding mode.  */
  26
  27 double
  28 __ceil (double x)
  29 {
  30   double two52 = copysign (0x1.0p52, x);
  31   double r, tmp;
  32
  33   __asm (
  34 #ifdef _IEEE_FP_INEXACT
  35          "addt/suim %2, %3, %1\n\tsubt/suim %1, %3, %0"
  36 #else
  37          "addt/sum %2, %3, %1\n\tsubt/sum %1, %3, %0"
  38 #endif
  39          : "=&f"(r), "=&f"(tmp)
  40          : "f"(-x), "f"(-two52));
  41
  42   /* Fix up the negation we did above, as well as handling -0 properly. */
  43   return copysign (r, x);
  44 }
  45
  46 weak_alias (__ceil, ceil)
  47 #ifdef NO_LONG_DOUBLE
  48 strong_alias (__ceil, __ceill)
  49 weak_alias (__ceil, ceill)
  50 #endif
  51 #if LONG_DOUBLE_COMPAT(libm, GLIBC_2_0)
  52 compat_symbol (libm, __ceil, ceill, GLIBC_2_0);
  53 #endif