gcc/libdecnumber/decRound.c

/* Temporary support for a libc-like fp environment for decimal float.
   Copyright (C) 2005 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to the Free
Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA.  */

#include "config.h"
#include "decContext.h"

#define FE_DEC_DOWNWARD 0
#define FE_DEC_TONEAREST 1
#define FE_DEC_TONEARESTFROMZERO 2
#define FE_DEC_TOWARDZERO 3
#define FE_DEC_UPWARD 4
#define FE_DEC_MAX 5

extern void __dfp_set_round (int);
extern int __dfp_get_round (void);
extern enum rounding __decGetRound (void);

/* FIXME: these should be in thread-local storage for runtime support.  */
static enum rounding __dfp_rounding_mode = DEC_ROUND_HALF_EVEN;

/* Set the decNumber rounding mode from the FE_DEC_* value in MODE.  */ 

void
__dfp_set_round (int mode)
{
  switch (mode)
    {
    case FE_DEC_DOWNWARD:
      __dfp_rounding_mode = DEC_ROUND_FLOOR; break;
    case FE_DEC_TONEAREST:
      __dfp_rounding_mode = DEC_ROUND_HALF_EVEN; break;
    case FE_DEC_TONEARESTFROMZERO:
      __dfp_rounding_mode = DEC_ROUND_HALF_UP; break;
    case FE_DEC_TOWARDZERO:
      __dfp_rounding_mode = DEC_ROUND_DOWN; break;
    case FE_DEC_UPWARD:
      __dfp_rounding_mode = DEC_ROUND_CEILING; break;
    default:
     /* We can't use assert in libgcc, so just return the default mode.  */
      __dfp_rounding_mode = DEC_ROUND_HALF_EVEN; break;
    }
}

/* Return the decNumber rounding mode as an FE_DEC_* value.  */

int
__dfp_get_round (void)
{
  int mode;

  switch (__dfp_rounding_mode)
    {
    case DEC_ROUND_FLOOR:
      mode = FE_DEC_DOWNWARD; break;
    case DEC_ROUND_HALF_EVEN:
      mode = FE_DEC_TONEAREST; break;
    case DEC_ROUND_HALF_UP:
      mode = FE_DEC_TONEARESTFROMZERO; break;
    case DEC_ROUND_DOWN:
      mode = FE_DEC_TOWARDZERO; break;
    case DEC_ROUND_CEILING:
      mode = FE_DEC_UPWARD; break;
    default:
      /* We shouldn't get here, but can't use assert in libgcc.  */
      mode = -1;
    }
  return mode;
}

/* Return the decNumber version of the current rounding mode.  */

enum rounding
__decGetRound (void)
{
  return __dfp_rounding_mode;
}