/* This file is part of GEGL

 *

 * GEGL is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 3 of the License, or (at your option) any later version.

 *

 * GEGL 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with GEGL; if not, see <http://www.gnu.org/licenses/>.

 *

 * Copyright 2009 Øyvind Kolås

 */

#ifndef __GEGL_LOOKUP_H__

#define __GEGL_LOOKUP_H__

G_BEGIN_DECLS

typedef     gfloat (* GeglLookupFunction) (gfloat   value,

                                           gpointer data);

#define GEGL_LOOKUP_MAX_ENTRIES   (819200)

typedef struct GeglLookup

{

  GeglLookupFunction function;

  gpointer           data;

  gint               shift;

  guint32            positive_min, positive_max, negative_min, negative_max;

  guint32            bitmask[GEGL_LOOKUP_MAX_ENTRIES/32];

  gfloat             table[];

} GeglLookup;

GeglLookup *gegl_lookup_new_full  (GeglLookupFunction  function,

                                   gpointer            data,

                                   gfloat              start,

                                   gfloat              end,

                                   gfloat              precision);

GeglLookup *gegl_lookup_new       (GeglLookupFunction  function,

                                   gpointer            data);

void        gegl_lookup_free      (GeglLookup         *lookup);

static inline gfloat

gegl_lookup (GeglLookup *lookup,

             gfloat      number)

{

  union

  {

    float   f;

    guint32 i;

  } u;

  guint i;

  u.f = number;

  i = u.i >> lookup->shift;

  if (i > lookup->positive_min &&

      i < lookup->positive_max)

    i = i - lookup->positive_min;

  else if (i > lookup->negative_min &&

           i < lookup->negative_max)

    i = i - lookup->negative_min + (lookup->positive_max - lookup->positive_min);

  else

    return lookup->function (number, lookup->data);

  if (!(lookup->bitmask[i/32] & (1<<(i & 31))))

    {

      lookup->table[i]= lookup->function (number, lookup->data);

      lookup->bitmask[i/32] |= (1<<(i & 31));

    }

  return lookup->table[i];

}

G_END_DECLS

#endif