gif_hash.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/******************************************************************************

gif_hash.h - magfic constants and declarations for GIF LZW

SPDX-License-Identifier: MIT

******************************************************************************/

#ifndef _GIF_HASH_H_
#define _GIF_HASH_H_

/** Begin JDK modifications to support building on Windows **/
#ifndef _WIN32
#include <unistd.h>
#endif
/** End JDK modifications to support building on Windows **/
#include <stdint.h>

#define HT_SIZE         8192    /* 12bits = 4096 or twice as big! */
#define HT_KEY_MASK     0x1FFF  /* 13bits keys */
#define HT_KEY_NUM_BITS 13      /* 13bits keys */
#define HT_MAX_KEY      8191    /* 13bits - 1, maximal code possible */
#define HT_MAX_CODE     4095    /* Biggest code possible in 12 bits. */

/* The 32 bits of the long are divided into two parts for the key & code:   */
/* 1. The code is 12 bits as our compression algorithm is limited to 12bits */
/* 2. The key is 12 bits Prefix code + 8 bit new char or 20 bits.           */
/* The key is the upper 20 bits.  The code is the lower 12. */
#define HT_GET_KEY(l)    (l >> 12)
#define HT_GET_CODE(l)   (l & 0x0FFF)
#define HT_PUT_KEY(l)    (l << 12)
#define HT_PUT_CODE(l)   (l & 0x0FFF)

typedef struct GifHashTableType {
    uint32_t HTable[HT_SIZE];
} GifHashTableType;

GifHashTableType *_InitHashTable(void);
void _ClearHashTable(GifHashTableType *HashTable);
void _InsertHashTable(GifHashTableType *HashTable, uint32_t Key, int Code);
int _ExistsHashTable(GifHashTableType *HashTable, uint32_t Key);

#endif /* _GIF_HASH_H_ */

/* end */