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/*****************************************************************************/
/* huffman.h Copyright (c) Ladislav Zezula 2003 */
/*---------------------------------------------------------------------------*/
/* Description : */
/*---------------------------------------------------------------------------*/
/* Date Ver Who Comment */
/* -------- ---- --- ------- */
/* xx.xx.xx 1.00 Lad The first version of huffman.h */
/* 03.05.03 2.00 Lad Added compression */
/* 08.12.03 2.01 Dan High-memory handling (> 0x80000000) */
/*****************************************************************************/
#ifndef __HUFFMAN_H__
#define __HUFFMAN_H__
//-----------------------------------------------------------------------------
// Defines
#define HUFF_ITEM_COUNT 0x203 // Number of items in the item pool
#define LINK_ITEM_COUNT 0x80 // Maximum number of quick-link items
//-----------------------------------------------------------------------------
// Structures and classes
// Input stream for Huffmann decompression
class TInputStream
{
public:
TInputStream(void * pvInBuffer, size_t cbInBuffer);
unsigned int Get1Bit();
unsigned int Peek7Bits();
unsigned int Get8Bits();
void SkipBits(unsigned int BitCount);
unsigned char * pbInBufferEnd; // End position in the the input buffer
unsigned char * pbInBuffer; // Current position in the the input buffer
unsigned int BitBuffer; // Input bit buffer
unsigned int BitCount; // Number of bits remaining in 'dwBitBuff'
};
// Output stream for Huffmann compression
class TOutputStream
{
public:
TOutputStream(void * pvOutBuffer, size_t cbOutLength);
void PutBits(unsigned int dwValue, unsigned int nBitCount);
void Flush();
unsigned char * pbOutBufferEnd; // End position in the output buffer
unsigned char * pbOutBuffer; // Current position in the output buffer
unsigned int BitBuffer; // Bit buffer
unsigned int BitCount; // Number of bits in the bit buffer
};
// A virtual tree item that represents the head of the item list
#define LIST_HEAD() ((THTreeItem *)(&pFirst))
enum TInsertPoint
{
InsertAfter = 1,
InsertBefore = 2
};
// Huffmann tree item
struct THTreeItem
{
THTreeItem() { pPrev = pNext = NULL; DecompressedValue = 0; Weight = 0; pParent = pChildLo = NULL; }
// ~THTreeItem() { RemoveItem(); }
void RemoveItem();
// void RemoveEntry();
THTreeItem * pNext; // Pointer to lower-weight tree item
THTreeItem * pPrev; // Pointer to higher-weight item
unsigned int DecompressedValue; // 08 - Decompressed byte value (also index in the array)
unsigned int Weight; // 0C - Weight
THTreeItem * pParent; // 10 - Pointer to parent item (NULL if none)
THTreeItem * pChildLo; // 14 - Pointer to the child with lower-weight child ("left child")
};
// Structure used for quick navigating in the huffmann tree.
// Allows skipping up to 7 bits in the compressed stream, thus
// decompressing a bit faster. Sometimes it can even get the decompressed
// byte directly.
struct TQuickLink
{
unsigned int ValidValue; // If greater than THuffmannTree::MinValidValue, the entry is valid
unsigned int ValidBits; // Number of bits that are valid for this item link
union
{
THTreeItem * pItem; // Pointer to the item within the Huffmann tree
unsigned int DecompressedValue; // Value for direct decompression
};
};
// Structure for Huffman tree (Size 0x3674 bytes). Because I'm not expert
// for the decompression, I do not know actually if the class is really a Hufmann
// tree. If someone knows the decompression details, please let me know
class THuffmannTree
{
public:
THuffmannTree(bool bCompression);
~THuffmannTree();
void LinkTwoItems(THTreeItem * pItem1, THTreeItem * pItem2);
void InsertItem(THTreeItem * item, TInsertPoint InsertPoint, THTreeItem * item2);
THTreeItem * FindHigherOrEqualItem(THTreeItem * pItem, unsigned int Weight);
THTreeItem * CreateNewItem(unsigned int DecompressedValue, unsigned int Weight, TInsertPoint InsertPoint);
unsigned int FixupItemPosByWeight(THTreeItem * pItem, unsigned int MaxWeight);
bool BuildTree(unsigned int CompressionType);
void IncWeightsAndRebalance(THTreeItem * pItem);
bool InsertNewBranchAndRebalance(unsigned int Value1, unsigned int Value2);
void EncodeOneByte(TOutputStream * os, THTreeItem * pItem);
unsigned int DecodeOneByte(TInputStream * is);
unsigned int Compress(TOutputStream * os, void * pvInBuffer, int cbInBuffer, int nCmpType);
unsigned int Decompress(void * pvOutBuffer, unsigned int cbOutLength, TInputStream * is);
THTreeItem ItemBuffer[HUFF_ITEM_COUNT]; // Buffer for tree items. No memory allocation is needed
unsigned int ItemsUsed; // Number of tree items used from ItemBuffer
// Head of the linear item list
THTreeItem * pFirst; // Pointer to the highest weight item
THTreeItem * pLast; // Pointer to the lowest weight item
THTreeItem * ItemsByByte[0x102]; // Array of item pointers, one for each possible byte value
TQuickLink QuickLinks[LINK_ITEM_COUNT]; // Array of quick-link items
unsigned int MinValidValue; // A minimum value of TQDecompress::ValidValue to be considered valid
unsigned int bIsCmp0; // 1 if compression type 0
};
#endif // __HUFFMAN_H__
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