libquadmath/quadmath-rounding-mode.h

   1 /* GCC Quad-Precision Math Library
   2    Copyright (C) 2012 Free Software Foundation, Inc.
   3
   4 This file is part of the libquadmath library.
   5 Libquadmath is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public
   7 License as published by the Free Software Foundation; either
   8 version 2 of the License, or (at your option) any later version.
   9
  10 Libquadmath 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with libquadmath; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  18 Boston, MA 02110-1301, USA.  */
  19
  20
  21 #ifndef QUADMATH_ROUNDING_MODE_H
  22 #define QUADMATH_ROUNDING_MODE_H
  23
  24 #include <stdbool.h>
  25
  26
  27 #if defined(HAVE_FENV_H)
  28 #  include <fenv.h>
  29 #endif /* HAVE_FENV_H */
  30
  31 static inline int
  32 get_rounding_mode (void)
  33 {
  34 #if defined(HAVE_FENV_H) && (defined(FE_DOWNWARD) || defined(FE_TONEAREST) \
  35                              || defined(FE_TOWARDZERO) || defined(FE_UPWARD))
  36   return fegetround ();
  37 #else
  38   return 0;
  39 #endif
  40 }
  41
  42 static inline bool
  43 round_away (bool negative, bool last_digit_odd, bool half_bit, bool more_bits,
  44             int mode)
  45 {
  46   switch (mode)
  47     {
  48 #ifdef FE_DOWNWARD
  49     case FE_DOWNWARD:
  50       return negative && (half_bit || more_bits);
  51 #endif
  52
  53 #ifdef FE_DOWNWARD
  54     case FE_TONEAREST:
  55       return half_bit && (last_digit_odd || more_bits);
  56 #endif
  57
  58 #ifdef FE_TOWARDZERO
  59     case FE_TOWARDZERO:
  60       return false;
  61 #endif
  62
  63
  64 #ifdef FE_UPWARD
  65     case FE_UPWARD:
  66       return !negative && (half_bit || more_bits);
  67 #endif
  68
  69     default:
  70       return false;
  71     }
  72 }
  73
  74 #endif /* QUADMATH_ROUNDING_MODE_H  */