cast.hh

// Copyright (C) 2001, 2002, 2003, 2004  EPITA Research and Development Laboratory
//
// This file is part of the Olena Library.  This library is free
// software; you can redistribute it and/or modify it under the terms
// of the GNU General Public License version 2 as published by the
// Free Software Foundation.
//
// This library 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 library; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
// MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free
// software library without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
// file, or you compile this file and link it with other files to
// produce an executable, this file does not by itself cause the
// resulting executable to be covered by the GNU General Public
// License.  This exception does not however invalidate any other
// reasons why the executable file might be covered by the GNU General
// Public License.

#ifndef NTG_UTILS_CAST_HH
# define NTG_UTILS_CAST_HH

# include <ntg/config/system.hh>
# include <ntg/core/macros.hh>
# include <ntg/core/predecls.hh>
# include <ntg/core/type_traits.hh>
# include <ntg/real/real_value.hh>

// FIXME: this file is completely broken, taking float_value as
// parameter does not make sense.

/*-------.
| macros |
`-------*/

# define TO_NTG_CAST(Dest)                              \
  template<class T>                                     \
  inline ntg_##Dest##_type(T) to_##Dest##_ntg(T val)    \
  {                                                     \
    return static_cast<ntg_##Dest##_type(T)>(val);      \
  }

namespace ntg {

  /*---------.
  | to_ntg() |
  `---------*/

  template<class T>
  inline ntg_type(T) to_ntg(T val)
  {
    return static_cast<ntg_type(T)>(val);
  }

  TO_NTG_CAST(signed)

  namespace cast {

    // FIXME: force does not seem to have any reason to live.

    /*------.
    | force |
    `------*/

    // a cast is performed instead of a constructor (unsafe one) call
    // because this last one may not be available with the good
    // signature.
    template<class Tdest, class Tsrc> inline
    const Tdest
    force(const Tsrc& val)
    {
      return ntg_unsafe_type(Tdest)(val);
    }

    /*------.
    | bound |
    `------*/

    // Like cast::force, but with saturation.
    template<class Tdest, class Tsrc> inline
    const Tdest
    bound(const Tsrc& val)
    {
      if (ntg_max_val(Tsrc) > ntg_max_val(Tdest))
        if (val > Tsrc(Tdest(ntg_max_val(Tdest))))
          return ntg_max_val(Tdest);
      if (ntg_min_val(Tsrc) < ntg_min_val(Tdest))
        if (val < Tsrc(Tdest(ntg_min_val(Tdest))))
          return ntg_min_val(Tdest);
      return val;
    }

    /*------.
    | round |
    `------*/

    namespace internal {
      template<class Tdest, class Tsrc>
      struct _round {
        // By default we don't define any function.
        // This cast does only work on float input.
      };

      template<class Tdest, class Tsrc>
      struct _round<Tdest, float_value<Tsrc> >
      {
        static const Tdest
        doit(const float_value<Tsrc>& val)
        {
          // FIXME: this code seems out of date.

#if 1
          // KLUDGE: Cast the rounded value to Tdest::value_t before
          // returning it as Tdest. Otherwise g++-3.* complains there
          // is no Tdest constructor taking a float argument.
          return (ntg_storage_type(Tdest)) round(val.exact());
#endif
          //      return round(val.exact());
        }
      };

      template<class Tdest>
      struct _round<Tdest, float_s >
      {
        static const Tdest
        doit(const float_s& val)
        {
          // FIXME: this code seems out of date.
#if 1
          // KLUDGE: Cast the rounded value to Tdest::value_t before
          // returning it as Tdest. Otherwise g++-3.* complains there
          // is no Tdest constructor taking a float argument.
          return (ntg_storage_type(Tdest)) roundf(val);
#endif
          //      return roundf(val);
        }
      };

      template<class Tdest>
      struct _round<Tdest, double>
      {
        static const Tdest
        doit(const float_d& val)
        {
          // FIXME: this code seems out of date.
#if 0
          // KLUDGE: Cast the rounded value to Tdest::value_t before
          // returning it as Tdest. Otherwise g++-3.0 complains there
          // is no Tdest constructor taking a float argument.
          return (ntg_storage_type(Tdest)) round(val);
#endif
          return round(val);
        }
      };

      template<class Tdest, class Tsrc>
      struct _round<float_value<Tdest>, float_value<Tsrc> >
      {
        static const Tdest
        doit(const float_value<Tsrc>& val)
        {
          return val.exact();
        }
      };

      template<class Tsrc>
      struct _round<float_s, float_value<Tsrc> >
      {
        static float_s
        doit(const float_value<Tsrc>& val)
        {
          return val.exact();
        }
      };

      template<class Tsrc>
      struct _round<float_d, float_value<Tsrc> >
      {
        static float_d
        doit(const float_value<Tsrc>& val)
        {
          return val.exact();
        }
      };

      template<>
      struct _round<float_s, float_d>
      {
        static float
        doit(const double& val)
        {
          return val;
        }
      };

      template<>
      struct _round<float_d, float_s>
      {
        static float_d
        doit(const float& val)
        {
          return val;
        }
      };
    } // end of internal.

    template<class Tdest, class Tsrc> inline
    const Tdest round(const Tsrc& val)
    {
      return internal::_round<Tdest, Tsrc>::doit(val);
    }

    /* Like cast::round, but with saturation.  */
    template<class Tdest, class Tsrc> inline
    const Tdest rbound(const Tsrc& val)
    {
      if (val > Tsrc(Tdest(ntg_max_val(Tdest))))
        return ntg_max_val(Tdest);
      if (val < Tsrc(Tdest(ntg_min_val(Tdest))))
        return ntg_min_val(Tdest);
      return cast::round<Tdest>(val);
    }

  } // end of cast.

} // end of ntg.

#endif // NTG_UTILS_CAST_HH

---