UEFITool/Tiano/EfiTianoCompress.c

/* EFI11/Tiano Compress Implementation

Copyright (c) 2014, Nikolaj Schlej
Copyright (c) 2006 - 2008, Intel Corporation
This program and the accompanying materials                          
are licensed and made available under the terms and conditions of the BSD License         
which accompanies this distribution.  The full text of the license may be found at        
http://opensource.org/licenses/bsd-license.php                                            

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
WITHWARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             

Module Name:

EfiTianoCompress.c

Abstract:

Compression routine. The compression algorithm is a mixture of
LZ77 and Huffman coding. LZ77 transforms the source data into a
sequence of Original Characters and Pointers to repeated strings.
This sequence is further divided into Blocks and Huffman codings
are applied to each Block.

*/

#include "EfiTianoCompress.h"

//
// Macro Definitions
//
#undef  UINT8_MAX
typedef INT32 NODE;
#define UINT8_MAX     0xff
#define UINT8_BIT     8
#define THRESHOLD     3
#define INIT_CRC      0
#define WNDBIT        19
#define WNDSIZ        (1U << WNDBIT)
#define MAXMATCH      256
#define BLKSIZ        (1U << 14)  // 16 * 1024U
#define PERC_FLAG     0x80000000U
#define CODE_BIT      16
#define NIL           0
#define MAX_HASH_VAL  (3 * WNDSIZ + (WNDSIZ / 512 + 1) * UINT8_MAX)
#define HASH(p, c)    ((p) + ((c) << (WNDBIT - 9)) + WNDSIZ * 2)
#define CRCPOLY       0xA001
#define UPDATE_CRC(c) mCrc = mCrcTable[(mCrc ^ (c)) & 0xFF] ^ (mCrc >> UINT8_BIT)

//
// C: the Char&Len Set; P: the Position Set; T: the exTra Set
//
#define NC    (UINT8_MAX + MAXMATCH + 2 - THRESHOLD)
#define CBIT  9
#define NP    (WNDBIT + 1)
//#define PBIT  5
#define NT    (CODE_BIT + 3)
#define TBIT  5
#if NT > NP
#define NPT NT
#else
#define NPT NP
#endif
//
// Function Prototypes
//

STATIC
	VOID
	PutDword(
	UINT32 Data
	);

STATIC
	INT32
	AllocateMemory (
	VOID
	);

STATIC
	VOID
	FreeMemory (
	VOID
	);

STATIC
	VOID
	InitSlide (
	VOID
	);

STATIC
	NODE
	Child (
	NODE   NodeQ,
	UINT8  CharC
	);

STATIC
	VOID
	MakeChild (
	NODE  NodeQ,
	UINT8 CharC,
	NODE  NodeR
	);

STATIC
	VOID
	Split (
	NODE Old
	);

STATIC
	VOID
	InsertNode (
	VOID
	);

STATIC
	VOID
	DeleteNode (
	VOID
	);

STATIC
	VOID
	GetNextMatch (
	VOID
	);

STATIC
	INT32
	Encode (
	VOID
	);

STATIC
	VOID
	CountTFreq (
	VOID
	);

STATIC
	VOID
	WritePTLen (
	INT32 Number,
	INT32 nbit,
	INT32 Special
	);

STATIC
	VOID
	WriteCLen (
	VOID
	);

STATIC
	VOID
	EncodeC (
	INT32 Value
	);

STATIC
	VOID
	EncodeP (
	UINT32 Value
	);

STATIC
	VOID
	SendBlock (
	VOID
	);

STATIC
	VOID
	Output (
	UINT32 c,
	UINT32 p
	);

STATIC
	VOID
	HufEncodeStart (
	VOID
	);

STATIC
	VOID
	HufEncodeEnd (
	VOID
	);

STATIC
	VOID
	MakeCrcTable (
	VOID
	);

STATIC
	VOID
	PutBits (
	INT32  Number,
	UINT32 Value
	);

STATIC
	INT32
	FreadCrc (
	UINT8 *Pointer,
	INT32 Number
	);

STATIC
	VOID
	InitPutBits (
	VOID
	);

STATIC
	VOID
	CountLen (
	INT32 Index
	);

STATIC
	VOID
	MakeLen (
	INT32 Root
	);

STATIC
	VOID
	DownHeap (
	INT32 Index
	);

STATIC
	VOID
	MakeCode (
	INT32       Number,
	UINT8 Len[  ],
	UINT16 Code[]
);

STATIC
	INT32
	MakeTree (
	INT32            NParm,
	UINT16  FreqParm[],
	UINT8   LenParm[ ],
	UINT16  CodeParm[]
);

//
//  Global Variables
//
STATIC UINT8  *mSrc, *mDst, *mSrcUpperLimit, *mDstUpperLimit;

STATIC UINT8  *mLevel, *mText, *mChildCount, *mBuf, mCLen[NC], mPTLen[NPT], *mLen;
STATIC INT16  mHeap[NC + 1];
STATIC INT32  mRemainder, mMatchLen, mBitCount, mHeapSize, mN;
STATIC UINT32 mBufSiz = 0, mOutputPos, mOutputMask, mSubBitBuf, mCrc;
STATIC UINT32 mCompSize, mOrigSize;

STATIC UINT16 *mFreq, *mSortPtr, mLenCnt[17], mLeft[2 * NC - 1], mRight[2 * NC - 1], mCrcTable[UINT8_MAX + 1],
	mCFreq[2 * NC - 1], mCCode[NC], mPFreq[2 * NP - 1], mPTCode[NPT], mTFreq[2 * NT - 1];

STATIC UINT8  mPbit;

STATIC NODE   mPos, mMatchPos, mAvail, *mPosition, *mParent, *mPrev, *mNext = NULL;

//
// functions
//
//
// functions
//
INT32
EfiCompress(
UINT8   *SrcBuffer,
UINT32  SrcSize,
UINT8   *DstBuffer,
UINT32  *DstSize
)
/*++

Routine Description:

The internal implementation of [Efi/Tiano]Compress().

Arguments:

SrcBuffer   - The buffer storing the source data
SrcSize     - The size of source data
DstBuffer   - The buffer to store the compressed data
DstSize     - On input, the size of DstBuffer; On output,
the size of the actual compressed data.

Returns:

EFI_BUFFER_TOO_SMALL  - The DstBuffer is too small. this case,
DstSize contains the size needed.
EFI_SUCCESS           - Compression is successful.
EFI_OUT_OF_RESOURCES  - No resource to complete function.
EFI_INVALID_PARAMETER - Parameter supplied is wrong.

--*/
{
    INT32 Status;

    //
    // Initializations
    //
    mPbit = 4;
    
    mBufSiz = 0;
    mBuf = NULL;
    mText = NULL;
    mLevel = NULL;
    mChildCount = NULL;
    mPosition = NULL;
    mParent = NULL;
    mPrev = NULL;
    mNext = NULL;

    mSrc = SrcBuffer;
    mSrcUpperLimit = mSrc + SrcSize;
    mDst = DstBuffer;
    mDstUpperLimit = mDst + *DstSize;

    PutDword(0L);
    PutDword(0L);

    MakeCrcTable();

    mOrigSize = mCompSize = 0;
    mCrc = INIT_CRC;

    //
    // Compress it
    //
    Status = Encode();
    if (Status) {
        return ERR_OUT_OF_RESOURCES;
    }
    //
    // Null terminate the compressed data
    //
    if (mDst < mDstUpperLimit) {
        *mDst++ = 0;
    }
    //
    // Fill compressed size and original size
    //
    mDst = DstBuffer;
    PutDword(mCompSize + 1);
    PutDword(mOrigSize);

    //
    // Return
    //
    if (mCompSize + 1 + 8 > *DstSize) {
        *DstSize = mCompSize + 1 + 8;
        return ERR_BUFFER_TOO_SMALL;
    }
    else {
        *DstSize = mCompSize + 1 + 8;
        return ERR_SUCCESS;
    }

}

INT32
	TianoCompress (
	UINT8   *SrcBuffer,
	UINT32  SrcSize,
	UINT8   *DstBuffer,
	UINT32  *DstSize
	)
	/*++

	Routine Description:

	The internal implementation of [Efi/Tiano]Compress().

	Arguments:

	SrcBuffer   - The buffer storing the source data
	SrcSize     - The size of source data
	DstBuffer   - The buffer to store the compressed data
	DstSize     - On input, the size of DstBuffer; On output,
	the size of the actual compressed data.
	Version     - The version of de/compression algorithm.
	Version 1 for UEFI 2.0 de/compression algorithm.
	Version 2 for Tiano de/compression algorithm.

	Returns:

	EFI_BUFFER_TOO_SMALL  - The DstBuffer is too small. this case,
	DstSize contains the size needed.
	EFI_SUCCESS           - Compression is successful.
	EFI_OUT_OF_RESOURCES  - No resource to complete function.
	EFI_INVALID_PARAMETER - Parameter supplied is wrong.

	--*/
{
	INT32 Status;

	//
	// Initializations
	//
    mPbit = 5;

	mBufSiz         = 0;
	mBuf            = NULL;
	mText           = NULL;
	mLevel          = NULL;
	mChildCount     = NULL;
	mPosition       = NULL;
	mParent         = NULL;
	mPrev           = NULL;
	mNext           = NULL;

	mSrc            = SrcBuffer;
	mSrcUpperLimit  = mSrc + SrcSize;
	mDst            = DstBuffer;
	mDstUpperLimit  = mDst +*DstSize;

	PutDword (0L);
	PutDword (0L);

	MakeCrcTable ();

	mOrigSize             = mCompSize = 0;
	mCrc                  = INIT_CRC;

	//
	// Compress it
	//
	Status = Encode ();
	if (Status) {
		return ERR_OUT_OF_RESOURCES;
	}
	//
	// Null terminate the compressed data
	//
	if (mDst < mDstUpperLimit) {
		*mDst++ = 0;
	}
	//
	// Fill compressed size and original size
	//
	mDst = DstBuffer;
	PutDword (mCompSize + 1);
	PutDword (mOrigSize);

	//
	// Return
	//
	if (mCompSize + 1 + 8 > *DstSize) {
		*DstSize = mCompSize + 1 + 8;
		return ERR_BUFFER_TOO_SMALL;
	} else {
		*DstSize = mCompSize + 1 + 8;
		return ERR_SUCCESS;
	}

}

STATIC
	VOID
	PutDword (
	UINT32 Data
	)
	/*++

	Routine Description:

	Put a DWORD to output stream

	Arguments:

	Data    - the DWORD to put

	Returns: (VOID)

	--*/
{
	if (mDst < mDstUpperLimit) {
		*mDst++ = (UINT8) (((UINT8) (Data)) & 0xff);
	}

	if (mDst < mDstUpperLimit) {
		*mDst++ = (UINT8) (((UINT8) (Data >> 0x08)) & 0xff);
	}

	if (mDst < mDstUpperLimit) {
		*mDst++ = (UINT8) (((UINT8) (Data >> 0x10)) & 0xff);
	}

	if (mDst < mDstUpperLimit) {
		*mDst++ = (UINT8) (((UINT8) (Data >> 0x18)) & 0xff);
	}
}

STATIC
	INT32
	AllocateMemory (
	VOID
	)
	/*++

	Routine Description:

	Allocate memory spaces for data structures used compression process

	Arguments: 
	VOID

	Returns:

	EFI_SUCCESS           - Memory is allocated successfully
	EFI_OUT_OF_RESOURCES  - Allocation fails

	--*/
{
	UINT32  Index;

	mText = malloc (WNDSIZ * 2 + MAXMATCH);
	for (Index = 0; Index < WNDSIZ * 2 + MAXMATCH; Index++) {
		mText[Index] = 0;
	}

	mLevel      = malloc ((WNDSIZ + UINT8_MAX + 1) * sizeof (*mLevel));
	mChildCount = malloc ((WNDSIZ + UINT8_MAX + 1) * sizeof (*mChildCount));
	mPosition   = malloc ((WNDSIZ + UINT8_MAX + 1) * sizeof (*mPosition));
	mParent     = malloc (WNDSIZ * 2 * sizeof (*mParent));
	mPrev       = malloc (WNDSIZ * 2 * sizeof (*mPrev));
	mNext       = malloc ((MAX_HASH_VAL + 1) * sizeof (*mNext));

	mBufSiz     = BLKSIZ;
	mBuf        = malloc (mBufSiz);
	while (mBuf == NULL) {
		mBufSiz = (mBufSiz / 10U) * 9U;
		if (mBufSiz < 4 * 1024U) {
			return ERR_OUT_OF_RESOURCES;
		}

		mBuf = malloc (mBufSiz);
	}

	mBuf[0] = 0;

	return ERR_SUCCESS;
}

VOID
	FreeMemory (
	VOID
	)
	/*++

	Routine Description:

	Called when compression is completed to free memory previously allocated.

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	if (mText != NULL) {
		free (mText);
	}

	if (mLevel != NULL) {
		free (mLevel);
	}

	if (mChildCount != NULL) {
		free (mChildCount);
	}

	if (mPosition != NULL) {
		free (mPosition);
	}

	if (mParent != NULL) {
		free (mParent);
	}

	if (mPrev != NULL) {
		free (mPrev);
	}

	if (mNext != NULL) {
		free (mNext);
	}

	if (mBuf != NULL) {
		free (mBuf);
	}

	return ;
}

STATIC
	VOID
	InitSlide (
	VOID
	)
	/*++

	Routine Description:

	Initialize String Info Log data structures

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	NODE  Index;

    for (Index = (NODE) WNDSIZ; Index <= (NODE) WNDSIZ + UINT8_MAX; Index++) {
		mLevel[Index]     = 1;
		mPosition[Index]  = NIL;  // sentinel 
	}

    for (Index = (NODE) WNDSIZ; Index < (NODE) WNDSIZ * 2; Index++) {
		mParent[Index] = NIL;
	}

	mAvail = 1;
    for (Index = 1; Index < (NODE) WNDSIZ - 1; Index++) {
		mNext[Index] = (NODE) (Index + 1);
	}

	mNext[WNDSIZ - 1] = NIL;
    for (Index = (NODE) WNDSIZ * 2; Index <= (NODE) MAX_HASH_VAL; Index++) {
		mNext[Index] = NIL;
	}
}

STATIC
	NODE
	Child (
	NODE  NodeQ,
	UINT8 CharC
	)
	/*++

	Routine Description:

	Find child node given the parent node and the edge character

	Arguments:

	NodeQ       - the parent node
	CharC       - the edge character

	Returns:

	The child node (NIL if not found)  

	--*/
{
	NODE  NodeR;

	NodeR = mNext[HASH (NodeQ, CharC)];
	//
	// sentinel
	//
	mParent[NIL] = NodeQ;
	while (mParent[NodeR] != NodeQ) {
		NodeR = mNext[NodeR];
	}

	return NodeR;
}

STATIC
	VOID
	MakeChild (
	NODE  Parent,
	UINT8 CharC,
	NODE  Child
	)
	/*++

	Routine Description:

	Create a new child for a given parent node.

	Arguments:

	Parent       - the parent node
	CharC   - the edge character
	Child       - the child node

	Returns: (VOID)

	--*/
{
	NODE  Node1;
	NODE  Node2;

	Node1           = (NODE) HASH (Parent, CharC);
	Node2           = mNext[Node1];
	mNext[Node1]    = Child;
	mNext[Child]    = Node2;
	mPrev[Node2]    = Child;
	mPrev[Child]    = Node1;
	mParent[Child]  = Parent;
	mChildCount[Parent]++;
}

STATIC
	VOID
	Split (
	NODE Old
	)
	/*++

	Routine Description:

	Split a node.

	Arguments:

	Old     - the node to split

	Returns: (VOID)

	--*/
{
	NODE  New;
	NODE  TempNode;

	New               = mAvail;
	mAvail            = mNext[New];
	mChildCount[New]  = 0;
	TempNode          = mPrev[Old];
	mPrev[New]        = TempNode;
	mNext[TempNode]   = New;
	TempNode          = mNext[Old];
	mNext[New]        = TempNode;
	mPrev[TempNode]   = New;
	mParent[New]      = mParent[Old];
	mLevel[New]       = (UINT8) mMatchLen;
	mPosition[New]    = mPos;
	MakeChild (New, mText[mMatchPos + mMatchLen], Old);
	MakeChild (New, mText[mPos + mMatchLen], mPos);
}

STATIC
	VOID
	InsertNode (
	VOID
	)
	/*++

	Routine Description:

	Insert string info for current position into the String Info Log

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	NODE  NodeQ;
	NODE  NodeR;
	NODE  Index2;
	NODE  NodeT;
	UINT8 CharC;
	UINT8 *t1;
	UINT8 *t2;

	if (mMatchLen >= 4) {
		//
		// We have just got a long match, the target tree
		// can be located by MatchPos + 1. Traverse the tree
		// from bottom up to get to a proper starting point.
		// The usage of PERC_FLAG ensures proper node deletion
		// DeleteNode() later.
		//
		mMatchLen--;
		NodeR = (NODE) ((mMatchPos + 1) | WNDSIZ);
		NodeQ = mParent[NodeR];
		while (NodeQ == NIL) {
			NodeR = mNext[NodeR];
			NodeQ = mParent[NodeR];
		}

		while (mLevel[NodeQ] >= mMatchLen) {
			NodeR = NodeQ;
			NodeQ = mParent[NodeQ];
		}

		NodeT = NodeQ;
		while (mPosition[NodeT] < 0) {
			mPosition[NodeT]  = mPos;
			NodeT             = mParent[NodeT];
		}

        if (NodeT < (NODE) WNDSIZ) {
			mPosition[NodeT] = (NODE) (mPos | (UINT32) PERC_FLAG);
		}
	} else {
		//
		// Locate the target tree
		//
		NodeQ = (NODE) (mText[mPos] + WNDSIZ);
		CharC = mText[mPos + 1];
		NodeR = Child (NodeQ, CharC);
		if (NodeR == NIL) {
			MakeChild (NodeQ, CharC, mPos);
			mMatchLen = 1;
			return ;
		}

		mMatchLen = 2;
	}
	//
	// Traverse down the tree to find a match.
	// Update Position value along the route.
	// Node split or creation is involved.
	//
	for (;;) {
        if (NodeR >= (NODE) WNDSIZ) {
			Index2    = MAXMATCH;
			mMatchPos = NodeR;
		} else {
			Index2    = mLevel[NodeR];
			mMatchPos = (NODE) (mPosition[NodeR] & (UINT32)~PERC_FLAG);
		}

		if (mMatchPos >= mPos) {
			mMatchPos -= WNDSIZ;
		}

		t1  = &mText[mPos + mMatchLen];
		t2  = &mText[mMatchPos + mMatchLen];
		while (mMatchLen < Index2) {
			if (*t1 != *t2) {
				Split (NodeR);
				return ;
			}

			mMatchLen++;
			t1++;
			t2++;
		}

		if (mMatchLen >= MAXMATCH) {
			break;
		}

		mPosition[NodeR]  = mPos;
		NodeQ             = NodeR;
		NodeR             = Child (NodeQ, *t1);
		if (NodeR == NIL) {
			MakeChild (NodeQ, *t1, mPos);
			return ;
		}

		mMatchLen++;
	}

	NodeT           = mPrev[NodeR];
	mPrev[mPos]     = NodeT;
	mNext[NodeT]    = mPos;
	NodeT           = mNext[NodeR];
	mNext[mPos]     = NodeT;
	mPrev[NodeT]    = mPos;
	mParent[mPos]   = NodeQ;
	mParent[NodeR]  = NIL;

	//
	// Special usage of 'next'
	//
	mNext[NodeR] = mPos;

}

STATIC
	VOID
	DeleteNode (
	VOID
	)
	/*++

	Routine Description:

	Delete outdated string info. (The Usage of PERC_FLAG
	ensures a clean deletion)

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	NODE  NodeQ;
	NODE  NodeR;
	NODE  NodeS;
	NODE  NodeT;
	NODE  NodeU;

	if (mParent[mPos] == NIL) {
		return ;
	}

	NodeR         = mPrev[mPos];
	NodeS         = mNext[mPos];
	mNext[NodeR]  = NodeS;
	mPrev[NodeS]  = NodeR;
	NodeR         = mParent[mPos];
	mParent[mPos] = NIL;
    if (NodeR >= (NODE) WNDSIZ) {
		return ;
	}

	mChildCount[NodeR]--;
	if (mChildCount[NodeR] > 1) {
		return ;
	}

	NodeT = (NODE) (mPosition[NodeR] & (UINT32)~PERC_FLAG);
	if (NodeT >= mPos) {
		NodeT -= WNDSIZ;
	}

	NodeS = NodeT;
	NodeQ = mParent[NodeR];
	NodeU = mPosition[NodeQ];
	while (NodeU & (UINT32) PERC_FLAG) {
		NodeU &= (UINT32)~PERC_FLAG;
		if (NodeU >= mPos) {
			NodeU -= WNDSIZ;
		}

		if (NodeU > NodeS) {
			NodeS = NodeU;
		}

		mPosition[NodeQ]  = (NODE) (NodeS | WNDSIZ);
		NodeQ             = mParent[NodeQ];
		NodeU             = mPosition[NodeQ];
	}

    if (NodeQ < (NODE) WNDSIZ) {
		if (NodeU >= mPos) {
			NodeU -= WNDSIZ;
		}

		if (NodeU > NodeS) {
			NodeS = NodeU;
		}

		mPosition[NodeQ] = (NODE) (NodeS | WNDSIZ | (UINT32) PERC_FLAG);
	}

	NodeS           = Child (NodeR, mText[NodeT + mLevel[NodeR]]);
	NodeT           = mPrev[NodeS];
	NodeU           = mNext[NodeS];
	mNext[NodeT]    = NodeU;
	mPrev[NodeU]    = NodeT;
	NodeT           = mPrev[NodeR];
	mNext[NodeT]    = NodeS;
	mPrev[NodeS]    = NodeT;
	NodeT           = mNext[NodeR];
	mPrev[NodeT]    = NodeS;
	mNext[NodeS]    = NodeT;
	mParent[NodeS]  = mParent[NodeR];
	mParent[NodeR]  = NIL;
	mNext[NodeR]    = mAvail;
	mAvail          = NodeR;
}

STATIC
	VOID
	GetNextMatch (
	VOID
	)
	/*++

	Routine Description:

	Advance the current position (read new data if needed).
	Delete outdated string info. Find a match string for current position.

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	INT32 Number;

	mRemainder--;
	mPos++;
	if (mPos == WNDSIZ * 2) {
		memmove (&mText[0], &mText[WNDSIZ], WNDSIZ + MAXMATCH);
		Number = FreadCrc (&mText[WNDSIZ + MAXMATCH], WNDSIZ);
		mRemainder += Number;
		mPos = WNDSIZ;
	}

	DeleteNode ();
	InsertNode ();
}

STATIC
	INT32
	Encode (
	VOID
	)
	/*++

	Routine Description:

	The mac controlling routine for compression process.

	Arguments: (VOID)

	Returns:

	EFI_SUCCESS           - The compression is successful
	EFI_OUT_0F_RESOURCES  - Not enough memory for compression process

	--*/
{
	INT32  Status;
	INT32       LastMatchLen;
	NODE        LastMatchPos;

	Status = AllocateMemory ();
	if (Status) {
		FreeMemory ();
		return Status;
	}

	InitSlide ();

	HufEncodeStart ();

	mRemainder  = FreadCrc (&mText[WNDSIZ], WNDSIZ + MAXMATCH);

	mMatchLen   = 0;
	mPos        = WNDSIZ;
	InsertNode ();
	if (mMatchLen > mRemainder) {
		mMatchLen = mRemainder;
	}

	while (mRemainder > 0) {
		LastMatchLen  = mMatchLen;
		LastMatchPos  = mMatchPos;
		GetNextMatch ();
		if (mMatchLen > mRemainder) {
			mMatchLen = mRemainder;
		}

		if (mMatchLen > LastMatchLen || LastMatchLen < THRESHOLD) {
			//
			// Not enough benefits are gained by outputting a pointer,
			// so just output the original character
			//
			Output (mText[mPos - 1], 0);

		} else {

			if (LastMatchLen == THRESHOLD) {
				if (((mPos - LastMatchPos - 2) & (WNDSIZ - 1)) > (1U << 11)) {
					Output (mText[mPos - 1], 0);
					continue;
				}
			}
			//
			// Outputting a pointer is beneficial enough, do it.
			//
			Output (
				LastMatchLen + (UINT8_MAX + 1 - THRESHOLD),
				(mPos - LastMatchPos - 2) & (WNDSIZ - 1)
				);
			LastMatchLen--;
			while (LastMatchLen > 0) {
				GetNextMatch ();
				LastMatchLen--;
			}

			if (mMatchLen > mRemainder) {
				mMatchLen = mRemainder;
			}
		}
	}

	HufEncodeEnd ();
	FreeMemory ();
	return ERR_SUCCESS;
}

STATIC
	VOID
	CountTFreq (
	VOID
	)
	/*++

	Routine Description:

	Count the frequencies for the Extra Set

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	INT32 Index;
	INT32 Index3;
	INT32 Number;
	INT32 Count;

	for (Index = 0; Index < NT; Index++) {
		mTFreq[Index] = 0;
	}

	Number = NC;
	while (Number > 0 && mCLen[Number - 1] == 0) {
		Number--;
	}

	Index = 0;
	while (Index < Number) {
		Index3 = mCLen[Index++];
		if (Index3 == 0) {
			Count = 1;
			while (Index < Number && mCLen[Index] == 0) {
				Index++;
				Count++;
			}

			if (Count <= 2) {
				mTFreq[0] = (UINT16) (mTFreq[0] + Count);
			} else if (Count <= 18) {
				mTFreq[1]++;
			} else if (Count == 19) {
				mTFreq[0]++;
				mTFreq[1]++;
			} else {
				mTFreq[2]++;
			}
		} else {
			mTFreq[Index3 + 2]++;
		}
	}
}

STATIC
	VOID
	WritePTLen (
	INT32 Number,
	INT32 nbit,
	INT32 Special
	)
	/*++

	Routine Description:

	Outputs the code length array for the Extra Set or the Position Set.

	Arguments:

	Number       - the number of symbols
	nbit    - the number of bits needed to represent 'n'
	Special - the special symbol that needs to be take care of

	Returns: (VOID)

	--*/
{
	INT32 Index;
	INT32 Index3;

	while (Number > 0 && mPTLen[Number - 1] == 0) {
		Number--;
	}

	PutBits (nbit, Number);
	Index = 0;
	while (Index < Number) {
		Index3 = mPTLen[Index++];
		if (Index3 <= 6) {
			PutBits (3, Index3);
		} else {
			PutBits (Index3 - 3, (1U << (Index3 - 3)) - 2);
		}

		if (Index == Special) {
			while (Index < 6 && mPTLen[Index] == 0) {
				Index++;
			}

			PutBits (2, (Index - 3) & 3);
		}
	}
}

STATIC
	VOID
	WriteCLen (
	VOID
	)
	/*++

	Routine Description:

	Outputs the code length array for Char&Length Set

	Arguments: (VOID)

	Returns: (VOID)

	--*/
{
	INT32 Index;
	INT32 Index3;
	INT32 Number;
	INT32 Count;

	Number = NC;
	while (Number > 0 && mCLen[Number - 1] == 0) {
		Number--;
	}

	PutBits (CBIT, Number);
	Index = 0;
	while (Index < Number) {
		Index3 = mCLen[Index++];
		if (Index3 == 0) {
			Count = 1;
			while (Index < Number && mCLen[Index] == 0) {
				Index++;
				Count++;
			}

			if (Count <= 2) {
				for (Index3 = 0; Index3 < Count; Index3++) {
					PutBits (mPTLen[0], mPTCode[0]);
				}
			} else if (Count <= 18) {
				PutBits (mPTLen[1], mPTCode[1]);
				PutBits (4, Count - 3);
			} else if (Count == 19) {
				PutBits (mPTLen[0], mPTCode[0]);
				PutBits (mPTLen[1], mPTCode[1]);
				PutBits (4, 15);
			} else {
				PutBits (mPTLen[2], mPTCode[2]);
				PutBits (CBIT, Count - 20);
			}
		} else {
			PutBits (mPTLen[Index3 + 2], mPTCode[Index3 + 2]);
		}
	}
}

STATIC
	VOID
	EncodeC (
	INT32 Value
	)
{
	PutBits (mCLen[Value], mCCode[Value]);
}

STATIC
	VOID
	EncodeP (
	UINT32 Value
	)
{
	UINT32  Index;
	UINT32  NodeQ;

	Index = 0;
	NodeQ = Value;
	while (NodeQ) {
		NodeQ >>= 1;
		Index++;
	}

	PutBits (mPTLen[Index], mPTCode[Index]);
	if (Index > 1) {
		PutBits (Index - 1, Value & (0xFFFFFFFFU >> (32 - Index + 1)));
	}
}

STATIC
	VOID
	SendBlock (
	VOID
	)
	/*++

	Routine Description:

	Huffman code the block and output it.

	Arguments: 
	(VOID)

	Returns: 
	(VOID)

	--*/
{
	UINT32  Index;
	UINT32  Index2;
	UINT32  Index3;
	UINT32  Flags;
	UINT32  Root;
	UINT32  Pos;
	UINT32  Size;
	Flags = 0;

	Root  = MakeTree (NC, mCFreq, mCLen, mCCode);
	Size  = mCFreq[Root];
	PutBits (16, Size);
	if (Root >= NC) {
		CountTFreq ();
		Root = MakeTree (NT, mTFreq, mPTLen, mPTCode);
		if (Root >= NT) {
			WritePTLen (NT, TBIT, 3);
		} else {
			PutBits (TBIT, 0);
			PutBits (TBIT, Root);
		}

		WriteCLen ();
	} else {
		PutBits (TBIT, 0);
		PutBits (TBIT, 0);
		PutBits (CBIT, 0);
		PutBits (CBIT, Root);
	}

	Root = MakeTree (NP, mPFreq, mPTLen, mPTCode);
	if (Root >= NP) {
		WritePTLen (NP, mPbit, -1);
	} else {
        PutBits (mPbit, 0);
        PutBits (mPbit, Root);
	}

	Pos = 0;
	for (Index = 0; Index < Size; Index++) {
		if (Index % UINT8_BIT == 0) {
			Flags = mBuf[Pos++];
		} else {
			Flags <<= 1;
		}

		if (Flags & (1U << (UINT8_BIT - 1))) {
			EncodeC (mBuf[Pos++] + (1U << UINT8_BIT));
			Index3 = mBuf[Pos++];
			for (Index2 = 0; Index2 < 3; Index2++) {
				Index3 <<= UINT8_BIT;
				Index3 += mBuf[Pos++];
			}

			EncodeP (Index3);
		} else {
			EncodeC (mBuf[Pos++]);
		}
	}

	for (Index = 0; Index < NC; Index++) {
		mCFreq[Index] = 0;
	}

	for (Index = 0; Index < NP; Index++) {
		mPFreq[Index] = 0;
	}
}

STATIC
	VOID
	Output (
	UINT32 CharC,
	UINT32 Pos
	)
	/*++

	Routine Description:

	Outputs an Original Character or a Pointer

	Arguments:

	CharC     - The original character or the 'String Length' element of a Pointer
	Pos     - The 'Position' field of a Pointer

	Returns: (VOID)

	--*/
{
	STATIC UINT32 CPos;

	if ((mOutputMask >>= 1) == 0) {
		mOutputMask = 1U << (UINT8_BIT - 1);
		//
		// Check the buffer overflow per outputting UINT8_BIT symbols
		// which is an Original Character or a Pointer. The biggest
		// symbol is a Pointer which occupies 5 bytes.
		//
		if (mOutputPos >= mBufSiz - 5 * UINT8_BIT) {
			SendBlock ();
			mOutputPos = 0;
		}

		CPos        = mOutputPos++;
		mBuf[CPos]  = 0;
	}

	mBuf[mOutputPos++] = (UINT8) CharC;
	mCFreq[CharC]++;
	if (CharC >= (1U << UINT8_BIT)) {
		mBuf[CPos] |= mOutputMask;
		mBuf[mOutputPos++]  = (UINT8) (Pos >> 24);
		mBuf[mOutputPos++]  = (UINT8) (Pos >> 16);
		mBuf[mOutputPos++]  = (UINT8) (Pos >> (UINT8_BIT));
		mBuf[mOutputPos++]  = (UINT8) Pos;
		CharC               = 0;
		while (Pos) {
			Pos >>= 1;
			CharC++;
		}

		mPFreq[CharC]++;
	}
}

STATIC
	VOID
	HufEncodeStart (
	VOID
	)
{
	INT32 Index;

	for (Index = 0; Index < NC; Index++) {
		mCFreq[Index] = 0;
	}

	for (Index = 0; Index < NP; Index++) {
		mPFreq[Index] = 0;
	}

	mOutputPos = mOutputMask = 0;
	InitPutBits ();
	return ;
}

STATIC
	VOID
	HufEncodeEnd (
	VOID
	)
{
	SendBlock ();

	//
	// Flush remaining bits
	//
	PutBits (UINT8_BIT - 1, 0);

	return ;
}

STATIC
	VOID
	MakeCrcTable (
	VOID
	)
{
	UINT32  Index;
	UINT32  Index2;
	UINT32  Temp;

	for (Index = 0; Index <= UINT8_MAX; Index++) {
		Temp = Index;
		for (Index2 = 0; Index2 < UINT8_BIT; Index2++) {
			if (Temp & 1) {
				Temp = (Temp >> 1) ^ CRCPOLY;
			} else {
				Temp >>= 1;
			}
		}

		mCrcTable[Index] = (UINT16) Temp;
	}
}

STATIC
	VOID
	PutBits (
	INT32  Number,
	UINT32 Value
	)
	/*++

	Routine Description:

	Outputs rightmost n bits of x

	Arguments:

	Number   - the rightmost n bits of the data is used
	x   - the data 

	Returns: (VOID)

	--*/
{
	UINT8 Temp;

	while (Number >= mBitCount) {
		//
		// Number -= mBitCount should never equal to 32
		//
		Temp = (UINT8) (mSubBitBuf | (Value >> (Number -= mBitCount)));
		if (mDst < mDstUpperLimit) {
			*mDst++ = Temp;
		}

		mCompSize++;
		mSubBitBuf  = 0;
		mBitCount   = UINT8_BIT;
	}

	mSubBitBuf |= Value << (mBitCount -= Number);
}

STATIC
	INT32
	FreadCrc (
	UINT8 *Pointer,
	INT32 Number
	)
	/*++

	Routine Description:

	Read source data

	Arguments:

	Pointer   - the buffer to hold the data
	Number   - number of bytes to read

	Returns:

	number of bytes actually read

	--*/
{
	INT32 Index;

	for (Index = 0; mSrc < mSrcUpperLimit && Index < Number; Index++) {
		*Pointer++ = *mSrc++;
	}

	Number = Index;

	Pointer -= Number;
	mOrigSize += Number;
	Index--;
	while (Index >= 0) {
		UPDATE_CRC (*Pointer++);
		Index--;
	}

	return Number;
}

STATIC
	VOID
	InitPutBits (
	VOID
	)
{
	mBitCount   = UINT8_BIT;
	mSubBitBuf  = 0;
}

STATIC
	VOID
	CountLen (
	INT32 Index
	)
	/*++

	Routine Description:

	Count the number of each code length for a Huffman tree.

	Arguments:

	Index   - the top node

	Returns: (VOID)

	--*/
{
	STATIC INT32  Depth = 0;

	if (Index < mN) {
		mLenCnt[(Depth < 16) ? Depth : 16]++;
	} else {
		Depth++;
		CountLen (mLeft[Index]);
		CountLen (mRight[Index]);
		Depth--;
	}
}

STATIC
	VOID
	MakeLen (
	INT32 Root
	)
	/*++

	Routine Description:

	Create code length array for a Huffman tree

	Arguments:

	Root   - the root of the tree

	Returns:

	VOID

	--*/
{
	INT32   Index;
	INT32   Index3;
	UINT32  Cum;

	for (Index = 0; Index <= 16; Index++) {
		mLenCnt[Index] = 0;
	}

	CountLen (Root);

	//
	// Adjust the length count array so that
	// no code will be generated longer than its designated length
	//
	Cum = 0;
	for (Index = 16; Index > 0; Index--) {
		Cum += mLenCnt[Index] << (16 - Index);
	}

	while (Cum != (1U << 16)) {
		mLenCnt[16]--;
		for (Index = 15; Index > 0; Index--) {
			if (mLenCnt[Index] != 0) {
				mLenCnt[Index]--;
				mLenCnt[Index + 1] += 2;
				break;
			}
		}

		Cum--;
	}

	for (Index = 16; Index > 0; Index--) {
		Index3 = mLenCnt[Index];
		Index3--;
		while (Index3 >= 0) {
			mLen[*mSortPtr++] = (UINT8) Index;
			Index3--;
		}
	}
}

STATIC
	VOID
	DownHeap (
	INT32 Index
	)
{
	INT32 Index2;
	INT32 Index3;

	//
	// priority queue: send Index-th entry down heap
	//
	Index3  = mHeap[Index];
	Index2  = 2 * Index;
	while (Index2 <= mHeapSize) {
		if (Index2 < mHeapSize && mFreq[mHeap[Index2]] > mFreq[mHeap[Index2 + 1]]) {
			Index2++;
		}

		if (mFreq[Index3] <= mFreq[mHeap[Index2]]) {
			break;
		}

		mHeap[Index]  = mHeap[Index2];
		Index         = Index2;
		Index2        = 2 * Index;
	}

	mHeap[Index] = (INT16) Index3;
}

STATIC
	VOID
	MakeCode (
	INT32       Number,
	UINT8 Len[  ],
	UINT16 Code[]
)
	/*++

	Routine Description:

	Assign code to each symbol based on the code length array

	Arguments:

	Number     - number of symbols
	Len   - the code length array
	Code  - stores codes for each symbol

	Returns: (VOID)

	--*/
{
	INT32   Index;
	UINT16  Start[18];

	Start[1] = 0;
	for (Index = 1; Index <= 16; Index++) {
		Start[Index + 1] = (UINT16) ((Start[Index] + mLenCnt[Index]) << 1);
	}

	for (Index = 0; Index < Number; Index++) {
		Code[Index] = Start[Len[Index]]++;
	}
}

STATIC
	INT32
	MakeTree (
	INT32            NParm,
	UINT16  FreqParm[],
	UINT8   LenParm[ ],
	UINT16  CodeParm[]
)
	/*++

	Routine Description:

	Generates Huffman codes given a frequency distribution of symbols

	Arguments:

	NParm    - number of symbols
	FreqParm - frequency of each symbol
	LenParm  - code length for each symbol
	CodeParm - code for each symbol

	Returns:

	Root of the Huffman tree.

	--*/
{
	INT32 Index;
	INT32 Index2;
	INT32 Index3;
	INT32 Avail;

	//
	// make tree, calculate len[], return root
	//
	mN        = NParm;
	mFreq     = FreqParm;
	mLen      = LenParm;
	Avail     = mN;
	mHeapSize = 0;
	mHeap[1]  = 0;
	for (Index = 0; Index < mN; Index++) {
		mLen[Index] = 0;
		if (mFreq[Index]) {
			mHeapSize++;
			mHeap[mHeapSize] = (INT16) Index;
		}
	}

	if (mHeapSize < 2) {
		CodeParm[mHeap[1]] = 0;
		return mHeap[1];
	}

	for (Index = mHeapSize / 2; Index >= 1; Index--) {
		//
		// make priority queue
		//
		DownHeap (Index);
	}

	mSortPtr = CodeParm;
	do {
		Index = mHeap[1];
		if (Index < mN) {
			*mSortPtr++ = (UINT16) Index;
		}

		mHeap[1] = mHeap[mHeapSize--];
		DownHeap (1);
		Index2 = mHeap[1];
		if (Index2 < mN) {
			*mSortPtr++ = (UINT16) Index2;
		}

		Index3        = Avail++;
		mFreq[Index3] = (UINT16) (mFreq[Index] + mFreq[Index2]);
		mHeap[1]      = (INT16) Index3;
		DownHeap (1);
		mLeft[Index3]   = (UINT16) Index;
		mRight[Index3]  = (UINT16) Index2;
	} while (mHeapSize > 1);

	mSortPtr = CodeParm;
	MakeLen (Index3);
	MakeCode (NParm, LenParm, CodeParm);

	//
	// return root
	//
	return Index3;
}