1 /*
   2  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
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   6  * published by the Free Software Foundation.  Oracle designates this
   7  * particular file as subject to the "Classpath" exception as provided
   8  * by Oracle in the LICENSE file that accompanied this code.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  */
  24 
  25 /******************************************************************************
  26 
  27 gif_hash.h - magfic constants and declarations for GIF LZW
  28 
  29 ******************************************************************************/
  30 
  31 #ifndef _GIF_HASH_H_
  32 #define _GIF_HASH_H_
  33 

  34 #include <stdint.h>
  35 
  36 #define HT_SIZE                 8192       /* 12bits = 4096 or twice as big! */
  37 #define HT_KEY_MASK             0x1FFF                        /* 13bits keys */
  38 #define HT_KEY_NUM_BITS         13                            /* 13bits keys */
  39 #define HT_MAX_KEY              8191    /* 13bits - 1, maximal code possible */
  40 #define HT_MAX_CODE             4095    /* Biggest code possible in 12 bits. */
  41 
  42 /* The 32 bits of the long are divided into two parts for the key & code:   */
  43 /* 1. The code is 12 bits as our compression algorithm is limited to 12bits */
  44 /* 2. The key is 12 bits Prefix code + 8 bit new char or 20 bits.           */
  45 /* The key is the upper 20 bits.  The code is the lower 12. */
  46 #define HT_GET_KEY(l)   (l >> 12)
  47 #define HT_GET_CODE(l)  (l & 0x0FFF)
  48 #define HT_PUT_KEY(l)   (l << 12)
  49 #define HT_PUT_CODE(l)  (l & 0x0FFF)
  50 
  51 typedef struct GifHashTableType {
  52     uint32_t HTable[HT_SIZE];
  53 } GifHashTableType;
  54 
  55 GifHashTableType *_InitHashTable(void);
  56 void _ClearHashTable(GifHashTableType *HashTable);
  57 void _InsertHashTable(GifHashTableType *HashTable, uint32_t Key, int Code);
  58 int _ExistsHashTable(GifHashTableType *HashTable, uint32_t Key);
  59 
  60 #endif /* _GIF_HASH_H_ */
  61 
  62 /* end */
--- EOF ---