libdecnumber/decRound.c

   1 /* Temporary support for a libc-like fp environment for decimal float.
   2    Copyright (C) 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, USA.  */
  20
  21 #include "decContext.h"
  22
  23 #define FE_DEC_DOWNWARD 0
  24 #define FE_DEC_TONEAREST 1
  25 #define FE_DEC_TONEARESTFROMZERO 2
  26 #define FE_DEC_TOWARDZERO 3
  27 #define FE_DEC_UPWARD 4
  28 #define FE_DEC_MAX 5
  29
  30 extern void __dfp_set_round (int);
  31 extern int __dfp_get_round (void);
  32 extern enum rounding __decGetRound (void);
  33
  34 /* FIXME: these should be in thread-local storage for runtime support.  */
  35 static enum rounding __dfp_rounding_mode = DEC_ROUND_HALF_EVEN;
  36
  37 /* Set the decNumber rounding mode from the FE_DEC_* value in MODE.  */
  38
  39 void
  40 __dfp_set_round (int mode)
  41 {
  42   switch (mode)
  43     {
  44     case FE_DEC_DOWNWARD:
  45       __dfp_rounding_mode = DEC_ROUND_FLOOR; break;
  46     case FE_DEC_TONEAREST:
  47       __dfp_rounding_mode = DEC_ROUND_HALF_EVEN; break;
  48     case FE_DEC_TONEARESTFROMZERO:
  49       __dfp_rounding_mode = DEC_ROUND_HALF_UP; break;
  50     case FE_DEC_TOWARDZERO:
  51       __dfp_rounding_mode = DEC_ROUND_DOWN; break;
  52     case FE_DEC_UPWARD:
  53       __dfp_rounding_mode = DEC_ROUND_CEILING; break;
  54     default:
  55      /* We can't use assert in libgcc, so just return the default mode.  */
  56       __dfp_rounding_mode = DEC_ROUND_HALF_EVEN; break;
  57     }
  58 }
  59
  60 /* Return the decNumber rounding mode as an FE_DEC_* value.  */
  61
  62 int
  63 __dfp_get_round (void)
  64 {
  65   int mode;
  66
  67   switch (__dfp_rounding_mode)
  68     {
  69     case DEC_ROUND_FLOOR:
  70       mode = FE_DEC_DOWNWARD; break;
  71     case DEC_ROUND_HALF_EVEN:
  72       mode = FE_DEC_TONEAREST; break;
  73     case DEC_ROUND_HALF_UP:
  74       mode = FE_DEC_TONEARESTFROMZERO; break;
  75     case DEC_ROUND_DOWN:
  76       mode = FE_DEC_TOWARDZERO; break;
  77     case DEC_ROUND_CEILING:
  78       mode = FE_DEC_UPWARD; break;
  79     default:
  80       /* We shouldn't get here, but can't use assert in libgcc.  */
  81       mode = -1;
  82     }
  83   return mode;
  84 }
  85
  86 /* Return the decNumber version of the current rounding mode.  */
  87
  88 enum rounding
  89 __decGetRound (void)
  90 {
  91   return __dfp_rounding_mode;
  92 }