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
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    GCC is distributed in the hope that it will be useful, but WITHOUT
  12    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  14    License 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 "config.h"
  22 #include "decContext.h"
  23
  24 #define FE_DEC_DOWNWARD 0
  25 #define FE_DEC_TONEAREST 1
  26 #define FE_DEC_TONEARESTFROMZERO 2
  27 #define FE_DEC_TOWARDZERO 3
  28 #define FE_DEC_UPWARD 4
  29 #define FE_DEC_MAX 5
  30
  31 extern void __dfp_set_round (int);
  32 extern int __dfp_get_round (void);
  33 extern enum rounding __decGetRound (void);
  34
  35 /* FIXME: these should be in thread-local storage for runtime support.  */
  36 static enum rounding __dfp_rounding_mode = DEC_ROUND_HALF_EVEN;
  37
  38 /* Set the decNumber rounding mode from the FE_DEC_* value in MODE.  */
  39
  40 void
  41 __dfp_set_round (int mode)
  42 {
  43   switch (mode)
  44     {
  45     case FE_DEC_DOWNWARD:
  46       __dfp_rounding_mode = DEC_ROUND_FLOOR; break;
  47     case FE_DEC_TONEAREST:
  48       __dfp_rounding_mode = DEC_ROUND_HALF_EVEN; break;
  49     case FE_DEC_TONEARESTFROMZERO:
  50       __dfp_rounding_mode = DEC_ROUND_HALF_UP; break;
  51     case FE_DEC_TOWARDZERO:
  52       __dfp_rounding_mode = DEC_ROUND_DOWN; break;
  53     case FE_DEC_UPWARD:
  54       __dfp_rounding_mode = DEC_ROUND_CEILING; break;
  55     default:
  56      /* We can't use assert in libgcc, so just return the default mode.  */
  57       __dfp_rounding_mode = DEC_ROUND_HALF_EVEN; break;
  58     }
  59 }
  60
  61 /* Return the decNumber rounding mode as an FE_DEC_* value.  */
  62
  63 int
  64 __dfp_get_round (void)
  65 {
  66   int mode;
  67
  68   switch (__dfp_rounding_mode)
  69     {
  70     case DEC_ROUND_FLOOR:
  71       mode = FE_DEC_DOWNWARD; break;
  72     case DEC_ROUND_HALF_EVEN:
  73       mode = FE_DEC_TONEAREST; break;
  74     case DEC_ROUND_HALF_UP:
  75       mode = FE_DEC_TONEARESTFROMZERO; break;
  76     case DEC_ROUND_DOWN:
  77       mode = FE_DEC_TOWARDZERO; break;
  78     case DEC_ROUND_CEILING:
  79       mode = FE_DEC_UPWARD; break;
  80     default:
  81       /* We shouldn't get here, but can't use assert in libgcc.  */
  82       mode = -1;
  83     }
  84   return mode;
  85 }
  86
  87 /* Return the decNumber version of the current rounding mode.  */
  88
  89 enum rounding
  90 __decGetRound (void)
  91 {
  92   return __dfp_rounding_mode;
  93 }