1/****************************************************************************** 2* Declarations, global to other of the GIF-HASH.C module. * 3* * 4* Written by Gershon Elber, Jun 1989 * 5******************************************************************************* 6* History: * 7* 14 Jun 89 - Version 1.0 by Gershon Elber. * 8******************************************************************************/ 9 10#ifndef _GIF_HASH_H_ 11#define _GIF_HASH_H_ 12 13#ifdef HAVE_CONFIG_H 14#include <config.h> 15#endif 16 17/* Find a thirty-two bit int type */ 18#ifdef HAVE_STDINT_H 19#include <stdint.h> 20#endif 21#ifdef HAVE_INTTYPES_H 22#include <inttypes.h> 23#endif 24#ifdef HAVE_SYS_TYPES_H 25#include <sys/types.h> 26#endif 27#ifdef HAVE_UNISTD_H 28#include <unistd.h> 29#endif 30 31#ifdef HAVE_BASETSD_H 32#include <basetsd.h> 33#endif 34 35#define HT_SIZE 8192 /* 12bits = 4096 or twice as big! */ 36#define HT_KEY_MASK 0x1FFF /* 13bits keys */ 37#define HT_KEY_NUM_BITS 13 /* 13bits keys */ 38#define HT_MAX_KEY 8191 /* 13bits - 1, maximal code possible */ 39#define HT_MAX_CODE 4095 /* Biggest code possible in 12 bits. */ 40 41/* The 32 bits of the long are divided into two parts for the key & code: */ 42/* 1. The code is 12 bits as our compression algorithm is limited to 12bits */ 43/* 2. The key is 12 bits Prefix code + 8 bit new char or 20 bits. */ 44/* The key is the upper 20 bits. The code is the lower 12. */ 45#define HT_GET_KEY(l) (l >> 12) 46#define HT_GET_CODE(l) (l & 0x0FFF) 47#define HT_PUT_KEY(l) (l << 12) 48#define HT_PUT_CODE(l) (l & 0x0FFF) 49 50typedef struct GifHashTableType { 51 UINT32 HTable[HT_SIZE]; 52} GifHashTableType; 53 54GifHashTableType *_InitHashTable(void); 55void _ClearHashTable(GifHashTableType *HashTable); 56void _InsertHashTable(GifHashTableType *HashTable, UINT32 Key, int Code); 57int _ExistsHashTable(GifHashTableType *HashTable, UINT32 Key); 58 59#endif /* _GIF_HASH_H_ */ 60