/* ieee-utils/fp-aix.c

 * 

 * Copyright (C) 1996, 1997, 1998, 1999, 2000 Tim Mooney

 * 

 * This program 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 3 of the License, or (at

 * your option) any later version.

 * 

 * This program 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 this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 */

#include <math.h>

#include <fptrap.h>

#include <float.h>

#include <gsl/gsl_ieee_utils.h>

#include <gsl/gsl_errno.h>

/* GCC uses a common float.h for all platforms, and ignores all vendor

specific code in float.h. That causes problems with fprnd_t,

FP_RND_RZ, FP_RND_RN and FP_RND_RP on AIX.

Personally I consider that a bug, and was advised by a GCC developer

to report this as a bug, which I did.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46155

However, there is not universal agreement whether this is a gcc bug, so 

the issue needs to be worked around on AIX.  

David Kirkby, 26th October 2010. */

#if !HAVE_DECL_FPRND_T          

typedef unsigned short fprnd_t; 

#endif                          

#ifndef FP_RND_RZ   

#define FP_RND_RZ       0

#endif 

#ifndef FP_RND_RN

#define FP_RND_RN       1

#endif

#ifndef FP_RND_RP

#define FP_RND_RP       2

#endif

#ifndef FP_RND_RM

#define FP_RND_RM       3

#endif

int

gsl_ieee_set_mode (int precision, int rounding, int exception_mask)

{

  fptrap_t   mode = 0 ;

  fprnd_t    rnd  = 0 ;

  switch (precision)

    {

    /* I'm not positive about AIX only supporting default precision rounding,

     * but this is the best assumption until it's proven otherwise. */

    case GSL_IEEE_SINGLE_PRECISION:

      GSL_ERROR ("AIX only supports default precision rounding",

                 GSL_EUNSUP) ;

      break ;

    case GSL_IEEE_DOUBLE_PRECISION:

      GSL_ERROR ("AIX only supports default precision rounding",

                 GSL_EUNSUP) ;

      break ;

    case GSL_IEEE_EXTENDED_PRECISION:

      GSL_ERROR ("AIX only supports default precision rounding",

                 GSL_EUNSUP) ;

      break ;

    }

  switch (rounding)

    {

    case GSL_IEEE_ROUND_TO_NEAREST:

      rnd = FP_RND_RN ;

      fp_swap_rnd (rnd) ;

      break ;

    case GSL_IEEE_ROUND_DOWN:

      rnd = FP_RND_RM ;

      fp_swap_rnd (rnd) ;

      break ;

    case GSL_IEEE_ROUND_UP:

      rnd = FP_RND_RP ;

      fp_swap_rnd (rnd) ;

      break ;

    case GSL_IEEE_ROUND_TO_ZERO:

      rnd = FP_RND_RZ ;

      fp_swap_rnd (rnd) ;

      break ;

    default:

      rnd = FP_RND_RN ;

      fp_swap_rnd (rnd) ;

    }

  /* Turn on all the exceptions apart from 'inexact' */

  mode = TRP_INVALID | TRP_DIV_BY_ZERO | TRP_OVERFLOW | TRP_UNDERFLOW ;

  if (exception_mask & GSL_IEEE_MASK_INVALID)

    mode &= ~ TRP_INVALID ;

  if (exception_mask & GSL_IEEE_MASK_DENORMALIZED)

    {

      /* do nothing */

    }

  else 

    {

      GSL_ERROR ("AIX does not support the denormalized operand exception. "

                 "Use 'mask-denormalized' to work around this.",

                 GSL_EUNSUP) ;

    }

  if (exception_mask & GSL_IEEE_MASK_DIVISION_BY_ZERO)

    mode &= ~ TRP_DIV_BY_ZERO ;

  if (exception_mask & GSL_IEEE_MASK_OVERFLOW)

    mode &= ~ TRP_OVERFLOW ;

  if (exception_mask & GSL_IEEE_MASK_UNDERFLOW)

    mode &=  ~ TRP_UNDERFLOW ;

  if (exception_mask & GSL_IEEE_TRAP_INEXACT)

    {

      mode |= TRP_INEXACT ;

    }

  else

    {

      mode &= ~ TRP_INEXACT ;

    }

  /* AIX appears to require two steps -- first enable floating point traps

   * in general... */

  fp_trap(FP_TRAP_SYNC);

  /* next, enable the traps we're interested in */

  fp_enable(mode);

  return GSL_SUCCESS ;

}