/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/* Copyright (C) 2019-2021 Hans Petter Jansson
 *
 * This file is part of Chafa, a program that turns images into character art.
 *
 * Chafa 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.
 *
 * Chafa 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 Lesser General Public License
 * along with Chafa.  If not, see <http://www.gnu.org/licenses/>. */

#ifndef __CHAFA_COLOR_HASH_H__
#define __CHAFA_COLOR_HASH_H__

G_BEGIN_DECLS

#define CHAFA_COLOR_HASH_N_ENTRIES 16384

typedef struct
{
    guint32 map [CHAFA_COLOR_HASH_N_ENTRIES];
}
ChafaColorHash;

void   chafa_color_hash_init    (ChafaColorHash *color_hash);
void   chafa_color_hash_deinit  (ChafaColorHash *color_hash);

static inline guint
_chafa_color_hash_calc_hash (guint32 color)
{
    color &= 0x00ffffff;

    return (color ^ (color >> 7) ^ (color >> 14)) % CHAFA_COLOR_HASH_N_ENTRIES;
}

static inline void
chafa_color_hash_replace (ChafaColorHash *color_hash, guint32 color, guint8 pen)
{
    guint index = _chafa_color_hash_calc_hash (color);
    guint32 entry = (color << 8) | pen;

    color_hash->map [index] = entry;
}

static inline gint
chafa_color_hash_lookup (const ChafaColorHash *color_hash, guint32 color)
{
    guint index = _chafa_color_hash_calc_hash (color);
    guint32 entry = color_hash->map [index];

    if ((entry & 0xffffff00) == (color << 8))
        return entry & 0xff;

    return -1;
}

G_END_DECLS

#endif /* __CHAFA_COLOR_HASH_H__ */
