/* Copyright (C) 2001-2006 Artifex Software, Inc.
   All Rights Reserved.
  
  This file is part of GNU ghostscript

  GNU ghostscript is free software; you can redistribute it and/or
  modify it under the terms of the version 2 of the GNU General Public
  License as published by the Free Software Foundation.

  GNU ghostscript 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
  ghostscript; see the file COPYING. If not, write to the Free Software Foundation,
  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

*/
/* $Id: gdev8bcm.c,v 1.7 2007/09/11 15:23:52 Arabidopsis Exp $ */
/* 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++);
}
