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Huffman.h

//==========================================================================
//
//  THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
//  KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//  IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
//  PURPOSE.
//
//  Copyright (c) 1999 - 2001  On2 Technologies Inc. All Rights Reserved.
//
//--------------------------------------------------------------------------


/****************************************************************************
*
*   Module Title :     Huffman.h
*
*   Description  :     Video CODEC
*
*
*****************************************************************************
*/

#ifndef HUFFMAN_H
#define HUFFMAN_H

#include "type_aliases.h"
/****************************************************************************
*  Constants
*****************************************************************************
*/
#define NUM_HUFF_TABLES         80
#define DC_HUFF_OFFSET          0
#define AC_HUFF_OFFSET          16
#define AC_TABLE_2_THRESH       5
#define AC_TABLE_3_THRESH       14
#define AC_TABLE_4_THRESH       27

#define DC_HUFF_CHOICES         16
#define DC_HUFF_CHOICE_BITS     4

#define AC_HUFF_CHOICES         16
#define AC_HUFF_CHOICE_BITS     4

// Constants assosciated with entropy tokenisation. 
#define MAX_SINGLE_TOKEN_VALUE  6
#define DCT_VAL_CAT2_MIN        3
#define DCT_VAL_CAT3_MIN        7
#define DCT_VAL_CAT4_MIN        9
#define DCT_VAL_CAT5_MIN        13
#define DCT_VAL_CAT6_MIN        21
#define DCT_VAL_CAT7_MIN        37
#define DCT_VAL_CAT8_MIN        69

#define DCT_EOB_TOKEN           0
#define DCT_EOB_PAIR_TOKEN      1
#define DCT_EOB_TRIPLE_TOKEN    2
#define DCT_REPEAT_RUN_TOKEN    3
#define DCT_REPEAT_RUN2_TOKEN   4
#define DCT_REPEAT_RUN3_TOKEN   5
#define DCT_REPEAT_RUN4_TOKEN   6

#define DCT_SHORT_ZRL_TOKEN     7
#define DCT_ZRL_TOKEN           8

#define ONE_TOKEN               9       // Special tokens for -1,1,-2,2
#define MINUS_ONE_TOKEN         10 
#define TWO_TOKEN               11 
#define MINUS_TWO_TOKEN         12 

#define LOW_VAL_TOKENS          (MINUS_TWO_TOKEN + 1)
#define DCT_VAL_CATEGORY3       (LOW_VAL_TOKENS + 4)
#define DCT_VAL_CATEGORY4       (DCT_VAL_CATEGORY3 + 1)
#define DCT_VAL_CATEGORY5       (DCT_VAL_CATEGORY4 + 1)
#define DCT_VAL_CATEGORY6       (DCT_VAL_CATEGORY5 + 1)
#define DCT_VAL_CATEGORY7       (DCT_VAL_CATEGORY6 + 1)
#define DCT_VAL_CATEGORY8       (DCT_VAL_CATEGORY7 + 1)

#define DCT_RUN_CATEGORY1       (DCT_VAL_CATEGORY8 + 1)
#define DCT_RUN_CATEGORY1B      (DCT_RUN_CATEGORY1 + 5)
#define DCT_RUN_CATEGORY1C      (DCT_RUN_CATEGORY1B + 1)
#define DCT_RUN_CATEGORY2       (DCT_RUN_CATEGORY1C + 1)

// 35
#define MAX_ENTROPY_TOKENS      (DCT_RUN_CATEGORY2 + 2)  

/****************************************************************************
*  Types
*****************************************************************************
*/  

typedef char * HUFF_ENTRY_PTR;
typedef struct 
{            
    HUFF_ENTRY_PTR ZeroChild;
    HUFF_ENTRY_PTR OneChild;
    HUFF_ENTRY_PTR Previous;
    HUFF_ENTRY_PTR Next;
    INT32          Value;
    UINT32         Frequency;
    
} HUFF_ENTRY; 

/****************************************************************************
*   Data structures
*****************************************************************************
*/

extern UINT8    ExtraBitLengths_VP31[MAX_ENTROPY_TOKENS];

/****************************************************************************
*  Functions
*****************************************************************************
*/


#endif

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