/* Copyright (C) 1994 Aladdin Enterprises.  All rights reserved.
  
  This file is part of GNU Ghostscript.
  
  GNU Ghostscript is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY.  No author or distributor accepts responsibility to
  anyone for the consequences of using it or for whether it serves any
  particular purpose or works at all, unless he says so in writing.  Refer
  to the GNU Ghostscript General Public License for full details.
  
*/

/* gdev8bcm.c */
/* Dynamic color mapping for 8-bit displays */
#include "gx.h"
#include "gxdevice.h"
#include "gdev8bcm.h"

/* Initialize an 8-bit color map. */
void
gx_8bit_map_init(gx_8bit_color_map *pcm, int max_count)
{	int i;
	pcm->count = 0;
	pcm->max_count = max_count;
	for ( i = 0; i < gx_8bit_map_size; i++ )
	  pcm->map[i].rgb = gx_8bit_no_rgb;
}

/* Look up a color in an 8-bit color map. */
/* Return <0 if not found. */
int
gx_8bit_map_rgb_color(const gx_8bit_color_map *pcm, gx_color_value r,
  gx_color_value g, gx_color_value b)
{	ushort rgb = gx_8bit_rgb_key(r, g, b);
	const gx_8bit_map_entry *pme =
	  &pcm->map[(rgb * gx_8bit_map_spreader) % gx_8bit_map_size];
	for ( ; ; pme++ )
	  {	if ( pme->rgb == rgb )
		  return pme->index;
		else if ( pme->rgb == gx_8bit_no_rgb )
		  break;
	  }
	if ( pme != &pcm->map[gx_8bit_map_size] )
	  return pme - &pcm->map[gx_8bit_map_size];
	/* We ran off the end; wrap around and continue. */
	pme = &pcm->map[0];
	for ( ; ; pme++ )
	  {	if ( pme->rgb == rgb )
		  return pme->index;
		else if ( pme->rgb == gx_8bit_no_rgb )
		  return pme - &pcm->map[gx_8bit_map_size];
	  }
}

/* Add a color to an 8-bit color map after an unsuccessful lookup, */
/* and return its index.  Return <0 if the map is full. */
int
gx_8bit_add_rgb_color(gx_8bit_color_map *pcm, gx_color_value r,
  gx_color_value g, gx_color_value b)
{	int index;
	gx_8bit_map_entry *pme;
	if ( gx_8bit_map_is_full(pcm) )
	  return -1;
	index = gx_8bit_map_rgb_color(pcm, r, g, b);
	if ( index >= 0 )			/* shouldn't happen */
	  return index;
	pme = &pcm->map[-index];
	pme->rgb = gx_8bit_rgb_key(r, g, b);
	return (pme->index = pcm->count++);
}
