sysdeps/generic/get-rounding-mode.h

   1 /* Determine floating-point rounding mode within libc.  Generic version.
   2    Copyright (C) 2012-2023 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    <https://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 #include <stdlib.h>
  24
  25 /* Define values for FE_* modes not defined for this architecture.  */
  26 #ifdef FE_DOWNWARD
  27 # define ORIG_FE_DOWNWARD FE_DOWNWARD
  28 #else
  29 # define ORIG_FE_DOWNWARD 0
  30 #endif
  31 #ifdef FE_TONEAREST
  32 # define ORIG_FE_TONEAREST FE_TONEAREST
  33 #else
  34 # define ORIG_FE_TONEAREST 0
  35 #endif
  36 #ifdef FE_TOWARDZERO
  37 # define ORIG_FE_TOWARDZERO FE_TOWARDZERO
  38 #else
  39 # define ORIG_FE_TOWARDZERO 0
  40 #endif
  41 #ifdef FE_UPWARD
  42 # define ORIG_FE_UPWARD FE_UPWARD
  43 #else
  44 # define ORIG_FE_UPWARD 0
  45 #endif
  46 #define FE_CONSTRUCT_DISTINCT_VALUE(X, Y, Z) \
  47   ((((X) & 1) | ((Y) & 2) | ((Z) & 4)) ^ 7)
  48 #ifndef FE_DOWNWARD
  49 # define FE_DOWNWARD FE_CONSTRUCT_DISTINCT_VALUE (ORIG_FE_TONEAREST,    \
  50                                                   ORIG_FE_TOWARDZERO,   \
  51                                                   ORIG_FE_UPWARD)
  52 #endif
  53 #ifndef FE_TONEAREST
  54 # define FE_TONEAREST FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD,         \
  55                                                    ORIG_FE_TOWARDZERO,  \
  56                                                    ORIG_FE_UPWARD)
  57 #endif
  58 #ifndef FE_TOWARDZERO
  59 # define FE_TOWARDZERO FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD,        \
  60                                                     FE_TONEAREST,       \
  61                                                     ORIG_FE_UPWARD)
  62 #endif
  63 #ifndef FE_UPWARD
  64 # define FE_UPWARD FE_CONSTRUCT_DISTINCT_VALUE (FE_DOWNWARD,    \
  65                                                 FE_TONEAREST,   \
  66                                                 FE_TOWARDZERO)
  67 #endif
  68
  69 /* Return the floating-point rounding mode.  */
  70
  71 static inline int
  72 get_rounding_mode (void)
  73 {
  74 #if (defined _FPU_RC_DOWN                       \
  75      || defined _FPU_RC_NEAREST                 \
  76      || defined _FPU_RC_ZERO                    \
  77      || defined _FPU_RC_UP)
  78   fpu_control_t fc;
  79   const fpu_control_t mask = (0
  80 # ifdef _FPU_RC_DOWN
  81                               | _FPU_RC_DOWN
  82 # endif
  83 # ifdef _FPU_RC_NEAREST
  84                               | _FPU_RC_NEAREST
  85 # endif
  86 # ifdef _FPU_RC_ZERO
  87                               | _FPU_RC_ZERO
  88 # endif
  89 # ifdef _FPU_RC_UP
  90                               | _FPU_RC_UP
  91 # endif
  92                               );
  93
  94   _FPU_GETCW (fc);
  95   switch (fc & mask)
  96     {
  97 # ifdef _FPU_RC_DOWN
  98     case _FPU_RC_DOWN:
  99       return FE_DOWNWARD;
 100 # endif
 101
 102 # ifdef _FPU_RC_NEAREST
 103     case _FPU_RC_NEAREST:
 104       return FE_TONEAREST;
 105 # endif
 106
 107 # ifdef _FPU_RC_ZERO
 108     case _FPU_RC_ZERO:
 109       return FE_TOWARDZERO;
 110 # endif
 111
 112 # ifdef _FPU_RC_UP
 113     case _FPU_RC_UP:
 114       return FE_UPWARD;
 115 # endif
 116
 117     default:
 118       abort ();
 119     }
 120 #else
 121   return FE_TONEAREST;
 122 #endif
 123 }
 124
 125 #endif /* get-rounding-mode.h */