/* Copyright (C) 1992, 1995, 1996, 1998, 1999 artofcode LLC.  All rights reserved.
  
  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 2 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.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

/*$Id: gxfmap.h,v 1.3.6.1.2.1 2003/01/17 00:49:03 giles Exp $ */
/* Fraction map representation for Ghostscript */

#ifndef gxfmap_INCLUDED
#  define gxfmap_INCLUDED

#include "gsrefct.h"
#include "gsstype.h"
#include "gxfrac.h"
#include "gxtmap.h"

/*
 * Define a cached map from fracs to fracs.  Level 1 uses this only
 * for the transfer function; level 2 also uses it for black generation
 * and undercolor removal.  Note that reference counting macros must
 * be used to allocate, free, and assign references to gx_transfer_maps.
 *
 * NOTE: proc and closure are redundant.  Eventually closure will replace
 * proc.  For now, things are in an uneasy intermediate state where
 * proc = 0 means use closure.
 */
/* log2... must not be greater than frac_bits, and must be least 8. */
#define log2_transfer_map_size 8
#define transfer_map_size (1 << log2_transfer_map_size)
/*typedef struct gx_transfer_map_s gx_transfer_map; *//* in gxtmap.h */
struct gx_transfer_map_s {
    rc_header rc;
    gs_mapping_proc proc;	/* typedef is in gxtmap.h */
    gs_mapping_closure_t closure;	/* SEE ABOVE */
    /* The id changes whenever the map or function changes. */
    gs_id id;
    frac values[transfer_map_size];
};

extern_st(st_transfer_map);
#define public_st_transfer_map() /* in gscolor.c */\
  gs_public_st_composite(st_transfer_map, gx_transfer_map, "gx_transfer_map",\
    transfer_map_enum_ptrs, transfer_map_reloc_ptrs)

/* Set a transfer map to the identity map. */
void gx_set_identity_transfer(P1(gx_transfer_map *));

/*
 * Map a color fraction through a transfer map.  If the map is small,
 * we interpolate; if it is large, we don't, and save a lot of time.
 */
#define FRAC_MAP_INTERPOLATE (log2_transfer_map_size <= 8)
#if FRAC_MAP_INTERPOLATE

frac gx_color_frac_map(P2(frac, const frac *));		/* in gxcmap.c */

#  define gx_map_color_frac(pgs,cf,m)\
     (pgs->m->proc == gs_identity_transfer ? cf :\
      gx_color_frac_map(cf, &pgs->m->values[0]))

#else /* !FRAC_MAP_INTERPOLATE */

/* Do the lookup in-line. */
#  define gx_map_color_frac(pgs,cf,m)\
     (pgs->m->values[frac2bits(cf, log2_transfer_map_size)])

#endif /* (!)FRAC_MAP_INTERPOLATE */

/* Map a color fraction expressed as a byte through a transfer map. */
/* (We don't use this anywhere right now.) */
/****************
#if log2_transfer_map_size <= 8
#  define byte_to_tmx(b) ((b) >> (8 - log2_transfer_map_size))
#else
#  define byte_to_tmx(b)\
	(((b) << (log2_transfer_map_size - 8)) +\
	 ((b) >> (16 - log2_transfer_map_size)))
#endif
#define gx_map_color_frac_byte(pgs,b,m)\
 (pgs->m->values[byte_to_tmx(b)])
 ****************/

/* Map a floating point value through a transfer map. */
#define gx_map_color_float(pmap,v)\
  ((pmap)->values[(int)((v) * transfer_map_size + 0.5)] / frac_1_float)

/* Define a mapping procedure that just looks up the value in the cache. */
/* (It is equivalent to gx_map_color_float with the arguments swapped.) */
float gs_mapped_transfer(P2(floatp, const gx_transfer_map *));

/* Define an identity mapping procedure. */
/* Don't store this directly in proc/closure.proc: */
/* use gx_set_identity_transfer. */
float gs_identity_transfer(P2(floatp, const gx_transfer_map *));

#endif /* gxfmap_INCLUDED */