sysdeps/generic/get-rounding-mode.h

   1 /* Determine floating-point rounding mode within libc.  Generic version.
   2    Copyright (C) 2012-2014 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   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 #ifndef _GET_ROUNDING_MODE_H
  20 #define _GET_ROUNDING_MODE_H    1
  21
  22 #include <fpu_control.h>
  23
  24 /* Define values for FE_* modes not defined for this architecture.  */
  25 #ifdef FE_DOWNWARD
  26 # define ORIG_FE_DOWNWARD FE_DOWNWARD
  27 #else
  28 # define ORIG_FE_DOWNWARD 0
  29 #endif
  30 #ifdef FE_TONEAREST
  31 # define ORIG_FE_TONEAREST FE_TONEAREST
  32 #else
  33 # define ORIG_FE_TONEAREST 0
  34 #endif
  35 #ifdef FE_TOWARDZERO
  36 # define ORIG_FE_TOWARDZERO FE_TOWARDZERO
  37 #else
  38 # define ORIG_FE_TOWARDZERO 0
  39 #endif
  40 #ifdef FE_UPWARD
  41 # define ORIG_FE_UPWARD FE_UPWARD
  42 #else
  43 # define ORIG_FE_UPWARD 0
  44 #endif
  45 #define FE_CONSTRUCT_DISTINCT_VALUE(X, Y, Z) \
  46   ((((X) & 1) | ((Y) & 2) | ((Z) & 4)) ^ 7)
  47 #ifndef FE_DOWNWARD
  48 # define FE_DOWNWARD FE_CONSTRUCT_DISTINCT_VALUE (ORIG_FE_TONEAREST,    \
  49                                                   ORIG_FE_TOWARDZERO,   \
  50                                                   ORIG_FE_UPWARD)
  51 #endif
  52 #ifndef FE_TONEAREST
  53 # define FE_TONEAREST FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD,         \
  54                                                    ORIG_FE_TOWARDZERO,  \
  55                                                    ORIG_FE_UPWARD)
  56 #endif
  57 #ifndef FE_TOWARDZERO
  58 # define FE_TOWARDZERO FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD,        \
  59                                                     FE_TONEAREST,       \
  60                                                     ORIG_FE_UPWARD)
  61 #endif
  62 #ifndef FE_UPWARD
  63 # define FE_UPWARD FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD,    \
  64                                                 FE_TONEAREST,   \
  65                                                 FE_TOWARDZERO)
  66 #endif
  67
  68 /* Return the floating-point rounding mode.  */
  69
  70 static inline int
  71 get_rounding_mode (void)
  72 {
  73 #if (defined _FPU_RC_DOWN                       \
  74      || defined _FPU_RC_NEAREST                 \
  75      || defined _FPU_RC_ZERO                    \
  76      || defined _FPU_RC_UP)
  77   fpu_control_t fc;
  78   const fpu_control_t mask = (0
  79 # ifdef _FPU_RC_DOWN
  80                               | _FPU_RC_DOWN
  81 # endif
  82 # ifdef _FPU_RC_NEAREST
  83                               | _FPU_RC_NEAREST
  84 # endif
  85 # ifdef _FPU_RC_ZERO
  86                               | _FPU_RC_ZERO
  87 # endif
  88 # ifdef _FPU_RC_UP
  89                               | _FPU_RC_UP
  90 # endif
  91                               );
  92
  93   _FPU_GETCW (fc);
  94   switch (fc & mask)
  95     {
  96 # ifdef _FPU_RC_DOWN
  97     case _FPU_RC_DOWN:
  98       return FE_DOWNWARD;
  99 # endif
 100
 101 # ifdef _FPU_RC_NEAREST
 102     case _FPU_RC_NEAREST:
 103       return FE_TONEAREST;
 104 # endif
 105
 106 # ifdef _FPU_RC_ZERO
 107     case _FPU_RC_ZERO:
 108       return FE_TOWARDZERO;
 109 # endif
 110
 111 # ifdef _FPU_RC_UP
 112     case _FPU_RC_UP:
 113       return FE_UPWARD;
 114 # endif
 115
 116     default:
 117       abort ();
 118     }
 119 #else
 120   return FE_TONEAREST;
 121 #endif
 122 }
 123
 124 #endif /* get-rounding-mode.h */