LzFind.c

/* LzFind.c -- Match finder for LZ algorithms
   2008-10-04 : Igor Pavlov : Public domain */

#include <string.h>

#include "LzFind.h"
#include "LzHash.h"

#define kEmptyHashValue 0
#define kMaxValForNormalize ((UInt32)0xFFFFFFFF)
#define kNormalizeStepMin (1 << 10) /* it must be power of 2 */
#define kNormalizeMask (~(kNormalizeStepMin - 1))
#define kMaxHistorySize ((UInt32)3 << 30)

#define kStartMaxLen 3

static void LzInWindow_Free(CMatchFinder *p, ISzAlloc *alloc)
{
	if (!p->directInput)
	{
		alloc->Free(alloc, p->bufferBase);
		p->bufferBase = 0;
	}
}

/* keepSizeBefore + keepSizeAfter + keepSizeReserv must be < 4G) */

static int LzInWindow_Create(CMatchFinder *p, UInt32 keepSizeReserv, ISzAlloc *alloc)
{
	UInt32 blockSize = p->keepSizeBefore + p->keepSizeAfter + keepSizeReserv;
	if (p->directInput)
	{
		p->blockSize = blockSize;
		return 1;
	}
	if (p->bufferBase == 0 || p->blockSize != blockSize)
	{
		LzInWindow_Free(p, alloc);
		p->blockSize = blockSize;
		p->bufferBase = (Byte *)alloc->Alloc(alloc, (size_t)blockSize);
	}
	return (p->bufferBase != 0);
}

Byte *MatchFinder_GetPointerToCurrentPos(CMatchFinder *p) { return p->buffer; }
Byte MatchFinder_GetIndexByte(CMatchFinder *p, Int32 index) { return p->buffer[index]; }

UInt32 MatchFinder_GetNumAvailableBytes(CMatchFinder *p) { return p->streamPos - p->pos; }

void MatchFinder_ReduceOffsets(CMatchFinder *p, UInt32 subValue)
{
	p->posLimit -= subValue;
	p->pos -= subValue;
	p->streamPos -= subValue;
}

static void MatchFinder_ReadBlock(CMatchFinder *p)
{
	if (p->streamEndWasReached || p->result != SZ_OK)
		return;
	for (;;)
	{
		Byte *dest = p->buffer + (p->streamPos - p->pos);
		size_t size = (p->bufferBase + p->blockSize - dest);
		if (size == 0)
			return;
		p->result = p->stream->Read(p->stream, dest, &size);
		if (p->result != SZ_OK)
			return;
		if (size == 0)
		{
			p->streamEndWasReached = 1;
			return;
		}
		p->streamPos += (UInt32)size;
		if (p->streamPos - p->pos > p->keepSizeAfter)
			return;
	}
}

void MatchFinder_MoveBlock(CMatchFinder *p)
{
	memmove(p->bufferBase,
		p->buffer - p->keepSizeBefore,
		(size_t)(p->streamPos - p->pos + p->keepSizeBefore));
	p->buffer = p->bufferBase + p->keepSizeBefore;
}

int MatchFinder_NeedMove(CMatchFinder *p)
{
	/* if (p->streamEndWasReached) return 0; */
	return ((size_t)(p->bufferBase + p->blockSize - p->buffer) <= p->keepSizeAfter);
}

void MatchFinder_ReadIfRequired(CMatchFinder *p)
{
	if (p->streamEndWasReached)
		return;
	if (p->keepSizeAfter >= p->streamPos - p->pos)
		MatchFinder_ReadBlock(p);
}

static void MatchFinder_CheckAndMoveAndRead(CMatchFinder *p)
{
	if (MatchFinder_NeedMove(p))
		MatchFinder_MoveBlock(p);
	MatchFinder_ReadBlock(p);
}

static void MatchFinder_SetDefaultSettings(CMatchFinder *p)
{
	p->cutValue = 32;
	p->btMode = 1;
	p->numHashBytes = 4;
	/* p->skipModeBits = 0; */
	p->directInput = 0;
	p->bigHash = 0;
}

#define kCrcPoly 0xEDB88320

void MatchFinder_Construct(CMatchFinder *p)
{
	UInt32 i;
	p->bufferBase = 0;
	p->directInput = 0;
	p->hash = 0;
	MatchFinder_SetDefaultSettings(p);

	for (i = 0; i < 256; i++)
	{
		UInt32 r = i;
		int j;
		for (j = 0; j < 8; j++)
			r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
		p->crc[i] = r;
	}
}

static void MatchFinder_FreeThisClassMemory(CMatchFinder *p, ISzAlloc *alloc)
{
	alloc->Free(alloc, p->hash);
	p->hash = 0;
}

void MatchFinder_Free(CMatchFinder *p, ISzAlloc *alloc)
{
	MatchFinder_FreeThisClassMemory(p, alloc);
	LzInWindow_Free(p, alloc);
}

static CLzRef* AllocRefs(UInt32 num, ISzAlloc *alloc)
{
	size_t sizeInBytes = (size_t)num * sizeof(CLzRef);
	if (sizeInBytes / sizeof(CLzRef) != num)
		return 0;
	return (CLzRef *)alloc->Alloc(alloc, sizeInBytes);
}

int MatchFinder_Create(CMatchFinder *p, UInt32 historySize,
		       UInt32 keepAddBufferBefore, UInt32 matchMaxLen, UInt32 keepAddBufferAfter,
		       ISzAlloc *alloc)
{
	UInt32 sizeReserv;
	if (historySize > kMaxHistorySize)
	{
		MatchFinder_Free(p, alloc);
		return 0;
	}
	sizeReserv = historySize >> 1;
	if (historySize > ((UInt32)2 << 30))
		sizeReserv = historySize >> 2;
	sizeReserv += (keepAddBufferBefore + matchMaxLen + keepAddBufferAfter) / 2 + (1 << 19);

	p->keepSizeBefore = historySize + keepAddBufferBefore + 1;
	p->keepSizeAfter = matchMaxLen + keepAddBufferAfter;
	/* we need one additional byte, since we use MoveBlock after pos++ and before dictionary using */
	if (LzInWindow_Create(p, sizeReserv, alloc))
	{
		UInt32 newCyclicBufferSize = (historySize /* >> p->skipModeBits */) + 1;
		UInt32 hs;
		p->matchMaxLen = matchMaxLen;
		{
			p->fixedHashSize = 0;
			if (p->numHashBytes == 2)
				hs = (1 << 16) - 1;
			else
			{
				hs = historySize - 1;
				hs |= (hs >> 1);
				hs |= (hs >> 2);
				hs |= (hs >> 4);
				hs |= (hs >> 8);
				hs >>= 1;
				/* hs >>= p->skipModeBits; */
				hs |= 0xFFFF; /* don't change it! It's required for Deflate */
				if (hs > (1 << 24))
				{
					if (p->numHashBytes == 3)
						hs = (1 << 24) - 1;
					else
						hs >>= 1;
				}
			}
			p->hashMask = hs;
			hs++;
			if (p->numHashBytes > 2) p->fixedHashSize += kHash2Size;
			if (p->numHashBytes > 3) p->fixedHashSize += kHash3Size;
			if (p->numHashBytes > 4) p->fixedHashSize += kHash4Size;
			hs += p->fixedHashSize;
		}

		{
			UInt32 prevSize = p->hashSizeSum + p->numSons;
			UInt32 newSize;
			p->historySize = historySize;
			p->hashSizeSum = hs;
			p->cyclicBufferSize = newCyclicBufferSize;
			p->numSons = (p->btMode ? newCyclicBufferSize * 2 : newCyclicBufferSize);
			newSize = p->hashSizeSum + p->numSons;
			if (p->hash != 0 && prevSize == newSize)
				return 1;
			MatchFinder_FreeThisClassMemory(p, alloc);
			p->hash = AllocRefs(newSize, alloc);
			if (p->hash != 0)
			{
				p->son = p->hash + p->hashSizeSum;
				return 1;
			}
		}
	}
	MatchFinder_Free(p, alloc);
	return 0;
}

static void MatchFinder_SetLimits(CMatchFinder *p)
{
	UInt32 limit = kMaxValForNormalize - p->pos;
	UInt32 limit2 = p->cyclicBufferSize - p->cyclicBufferPos;
	if (limit2 < limit)
		limit = limit2;
	limit2 = p->streamPos - p->pos;
	if (limit2 <= p->keepSizeAfter)
	{
		if (limit2 > 0)
			limit2 = 1;
	}
	else
		limit2 -= p->keepSizeAfter;
	if (limit2 < limit)
		limit = limit2;
	{
		UInt32 lenLimit = p->streamPos - p->pos;
		if (lenLimit > p->matchMaxLen)
			lenLimit = p->matchMaxLen;
		p->lenLimit = lenLimit;
	}
	p->posLimit = p->pos + limit;
}

void MatchFinder_Init(CMatchFinder *p)
{
	UInt32 i;
	for (i = 0; i < p->hashSizeSum; i++)
		p->hash[i] = kEmptyHashValue;
	p->cyclicBufferPos = 0;
	p->buffer = p->bufferBase;
	p->pos = p->streamPos = p->cyclicBufferSize;
	p->result = SZ_OK;
	p->streamEndWasReached = 0;
	MatchFinder_ReadBlock(p);
	MatchFinder_SetLimits(p);
}

static UInt32 MatchFinder_GetSubValue(CMatchFinder *p)
{
	return (p->pos - p->historySize - 1) & kNormalizeMask;
}

void MatchFinder_Normalize3(UInt32 subValue, CLzRef *items, UInt32 numItems)
{
	UInt32 i;
	for (i = 0; i < numItems; i++)
	{
		UInt32 value = items[i];
		if (value <= subValue)
			value = kEmptyHashValue;
		else
			value -= subValue;
		items[i] = value;
	}
}

static void MatchFinder_Normalize(CMatchFinder *p)
{
	UInt32 subValue = MatchFinder_GetSubValue(p);
	MatchFinder_Normalize3(subValue, p->hash, p->hashSizeSum + p->numSons);
	MatchFinder_ReduceOffsets(p, subValue);
}

static void MatchFinder_CheckLimits(CMatchFinder *p)
{
	if (p->pos == kMaxValForNormalize)
		MatchFinder_Normalize(p);
	if (!p->streamEndWasReached && p->keepSizeAfter == p->streamPos - p->pos)
		MatchFinder_CheckAndMoveAndRead(p);
	if (p->cyclicBufferPos == p->cyclicBufferSize)
		p->cyclicBufferPos = 0;
	MatchFinder_SetLimits(p);
}

static UInt32 * Hc_GetMatchesSpec(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
				  UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue,
				  UInt32 *distances, UInt32 maxLen)
{
	son[_cyclicBufferPos] = curMatch;
	for (;;)
	{
		UInt32 delta = pos - curMatch;
		if (cutValue-- == 0 || delta >= _cyclicBufferSize)
			return distances;
		{
			const Byte *pb = cur - delta;
			curMatch = son[_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)];
			if (pb[maxLen] == cur[maxLen] && *pb == *cur)
			{
				UInt32 len = 0;
				while (++len != lenLimit)
					if (pb[len] != cur[len])
						break;
				if (maxLen < len)
				{
					*distances++ = maxLen = len;
					*distances++ = delta - 1;
					if (len == lenLimit)
						return distances;
				}
			}
		}
	}
}

UInt32 * GetMatchesSpec1(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
			 UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue,
			 UInt32 *distances, UInt32 maxLen)
{
	CLzRef *ptr0 = son + (_cyclicBufferPos << 1) + 1;
	CLzRef *ptr1 = son + (_cyclicBufferPos << 1);
	UInt32 len0 = 0, len1 = 0;
	for (;;)
	{
		UInt32 delta = pos - curMatch;
		if (cutValue-- == 0 || delta >= _cyclicBufferSize)
		{
			*ptr0 = *ptr1 = kEmptyHashValue;
			return distances;
		}
		{
			CLzRef *pair = son + ((_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
			const Byte *pb = cur - delta;
			UInt32 len = (len0 < len1 ? len0 : len1);
			if (pb[len] == cur[len])
			{
				if (++len != lenLimit && pb[len] == cur[len])
					while (++len != lenLimit)
						if (pb[len] != cur[len])
							break;
				if (maxLen < len)
				{
					*distances++ = maxLen = len;
					*distances++ = delta - 1;
					if (len == lenLimit)
					{
						*ptr1 = pair[0];
						*ptr0 = pair[1];
						return distances;
					}
				}
			}
			if (pb[len] < cur[len])
			{
				*ptr1 = curMatch;
				ptr1 = pair + 1;
				curMatch = *ptr1;
				len1 = len;
			}
			else
			{
				*ptr0 = curMatch;
				ptr0 = pair;
				curMatch = *ptr0;
				len0 = len;
			}
		}
	}
}

static void SkipMatchesSpec(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
			    UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue)
{
	CLzRef *ptr0 = son + (_cyclicBufferPos << 1) + 1;
	CLzRef *ptr1 = son + (_cyclicBufferPos << 1);
	UInt32 len0 = 0, len1 = 0;
	for (;;)
	{
		UInt32 delta = pos - curMatch;
		if (cutValue-- == 0 || delta >= _cyclicBufferSize)
		{
			*ptr0 = *ptr1 = kEmptyHashValue;
			return;
		}
		{
			CLzRef *pair = son + ((_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
			const Byte *pb = cur - delta;
			UInt32 len = (len0 < len1 ? len0 : len1);
			if (pb[len] == cur[len])
			{
				while (++len != lenLimit)
					if (pb[len] != cur[len])
						break;
				{
					if (len == lenLimit)
					{
						*ptr1 = pair[0];
						*ptr0 = pair[1];
						return;
					}
				}
			}
			if (pb[len] < cur[len])
			{
				*ptr1 = curMatch;
				ptr1 = pair + 1;
				curMatch = *ptr1;
				len1 = len;
			}
			else
			{
				*ptr0 = curMatch;
				ptr0 = pair;
				curMatch = *ptr0;
				len0 = len;
			}
		}
	}
}

#define MOVE_POS							\
	++p->cyclicBufferPos;						\
	p->buffer++;							\
	if (++p->pos == p->posLimit) MatchFinder_CheckLimits(p);

#define MOVE_POS_RET MOVE_POS return offset;

static void MatchFinder_MovePos(CMatchFinder *p) { MOVE_POS; }

#define GET_MATCHES_HEADER2(minLen, ret_op)				\
	UInt32 lenLimit; UInt32 hashValue; const Byte *cur; UInt32 curMatch; \
	lenLimit = p->lenLimit; { if (lenLimit < minLen) { MatchFinder_MovePos(p); ret_op; }} \
	cur = p->buffer;

#define GET_MATCHES_HEADER(minLen) GET_MATCHES_HEADER2(minLen, return 0)
#define SKIP_HEADER(minLen)        GET_MATCHES_HEADER2(minLen, continue)

#define MF_PARAMS(p) p->pos, p->buffer, p->son, p->cyclicBufferPos, p->cyclicBufferSize, p->cutValue

#define GET_MATCHES_FOOTER(offset, maxLen)				\
	offset = (UInt32)(GetMatchesSpec1(lenLimit, curMatch, MF_PARAMS(p), \
					  distances + offset, maxLen) - distances); MOVE_POS_RET;

#define SKIP_FOOTER							\
	SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p)); MOVE_POS;

static UInt32 Bt2_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
	UInt32 offset;
	GET_MATCHES_HEADER(2)
		HASH2_CALC;
	curMatch = p->hash[hashValue];
	p->hash[hashValue] = p->pos;
	offset = 0;
	GET_MATCHES_FOOTER(offset, 1)
		}

UInt32 Bt3Zip_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
	UInt32 offset;
	GET_MATCHES_HEADER(3)
		HASH_ZIP_CALC;
	curMatch = p->hash[hashValue];
	p->hash[hashValue] = p->pos;
	offset = 0;
	GET_MATCHES_FOOTER(offset, 2)
		}

static UInt32 Bt3_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
	UInt32 hash2Value, delta2, maxLen, offset;
	GET_MATCHES_HEADER(3)

		HASH3_CALC;

	delta2 = p->pos - p->hash[hash2Value];
	curMatch = p->hash[kFix3HashSize + hashValue];

	p->hash[hash2Value] =
		p->hash[kFix3HashSize + hashValue] = p->pos;


	maxLen = 2;
	offset = 0;
	if (delta2 < p->cyclicBufferSize && *(cur - delta2) == *cur)
	{
		for (; maxLen != lenLimit; maxLen++)
			if (cur[(ptrdiff_t)maxLen - delta2] != cur[maxLen])
				break;
		distances[0] = maxLen;
		distances[1] = delta2 - 1;
		offset = 2;
		if (maxLen == lenLimit)
		{
			SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p));
			MOVE_POS_RET;
		}
	}
	GET_MATCHES_FOOTER(offset, maxLen)
		}

static UInt32 Bt4_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
	UInt32 hash2Value, hash3Value, delta2, delta3, maxLen, offset;
	GET_MATCHES_HEADER(4)

		HASH4_CALC;

	delta2 = p->pos - p->hash[                hash2Value];
	delta3 = p->pos - p->hash[kFix3HashSize + hash3Value];
	curMatch = p->hash[kFix4HashSize + hashValue];

	p->hash[                hash2Value] =
		p->hash[kFix3HashSize + hash3Value] =
		p->hash[kFix4HashSize + hashValue] = p->pos;

	maxLen = 1;
	offset = 0;
	if (delta2 < p->cyclicBufferSize && *(cur - delta2) == *cur)
	{
		distances[0] = maxLen = 2;
		distances[1] = delta2 - 1;
		offset = 2;
	}
	if (delta2 != delta3 && delta3 < p->cyclicBufferSize && *(cur - delta3) == *cur)
	{
		maxLen = 3;
		distances[offset + 1] = delta3 - 1;
		offset += 2;
		delta2 = delta3;
	}
	if (offset != 0)
	{
		for (; maxLen != lenLimit; maxLen++)
			if (cur[(ptrdiff_t)maxLen - delta2] != cur[maxLen])
				break;
		distances[offset - 2] = maxLen;
		if (maxLen == lenLimit)
		{
			SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p));
			MOVE_POS_RET;
		}
	}
	if (maxLen < 3)
		maxLen = 3;
	GET_MATCHES_FOOTER(offset, maxLen)
		}

static UInt32 Hc4_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
	UInt32 hash2Value, hash3Value, delta2, delta3, maxLen, offset;
	GET_MATCHES_HEADER(4)

		HASH4_CALC;

	delta2 = p->pos - p->hash[                hash2Value];
	delta3 = p->pos - p->hash[kFix3HashSize + hash3Value];
	curMatch = p->hash[kFix4HashSize + hashValue];

	p->hash[                hash2Value] =
		p->hash[kFix3HashSize + hash3Value] =
		p->hash[kFix4HashSize + hashValue] = p->pos;

	maxLen = 1;
	offset = 0;
	if (delta2 < p->cyclicBufferSize && *(cur - delta2) == *cur)
	{
		distances[0] = maxLen = 2;
		distances[1] = delta2 - 1;
		offset = 2;
	}
	if (delta2 != delta3 && delta3 < p->cyclicBufferSize && *(cur - delta3) == *cur)
	{
		maxLen = 3;
		distances[offset + 1] = delta3 - 1;
		offset += 2;
		delta2 = delta3;
	}
	if (offset != 0)
	{
		for (; maxLen != lenLimit; maxLen++)
			if (cur[(ptrdiff_t)maxLen - delta2] != cur[maxLen])
				break;
		distances[offset - 2] = maxLen;
		if (maxLen == lenLimit)
		{
			p->son[p->cyclicBufferPos] = curMatch;
			MOVE_POS_RET;
		}
	}
	if (maxLen < 3)
		maxLen = 3;
	offset = (UInt32)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
					    distances + offset, maxLen) - (distances));
	MOVE_POS_RET
		}

UInt32 Hc3Zip_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
	UInt32 offset;
	GET_MATCHES_HEADER(3)
		HASH_ZIP_CALC;
	curMatch = p->hash[hashValue];
	p->hash[hashValue] = p->pos;
	offset = (UInt32)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
					    distances, 2) - (distances));
	MOVE_POS_RET
		}

static void Bt2_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
	do
	{
		SKIP_HEADER(2)
			HASH2_CALC;
		curMatch = p->hash[hashValue];
		p->hash[hashValue] = p->pos;
		SKIP_FOOTER
			}
	while (--num != 0);
}

void Bt3Zip_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
	do
	{
		SKIP_HEADER(3)
			HASH_ZIP_CALC;
		curMatch = p->hash[hashValue];
		p->hash[hashValue] = p->pos;
		SKIP_FOOTER
			}
	while (--num != 0);
}

static void Bt3_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
	do
	{
		UInt32 hash2Value;
		SKIP_HEADER(3)
			HASH3_CALC;
		curMatch = p->hash[kFix3HashSize + hashValue];
		p->hash[hash2Value] =
			p->hash[kFix3HashSize + hashValue] = p->pos;
		SKIP_FOOTER
			}
	while (--num != 0);
}

static void Bt4_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
	do
	{
		UInt32 hash2Value, hash3Value;
		SKIP_HEADER(4)
			HASH4_CALC;
		curMatch = p->hash[kFix4HashSize + hashValue];
		p->hash[                hash2Value] =
			p->hash[kFix3HashSize + hash3Value] = p->pos;
		p->hash[kFix4HashSize + hashValue] = p->pos;
		SKIP_FOOTER
			}
	while (--num != 0);
}

static void Hc4_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
	do
	{
		UInt32 hash2Value, hash3Value;
		SKIP_HEADER(4)
			HASH4_CALC;
		curMatch = p->hash[kFix4HashSize + hashValue];
		p->hash[                hash2Value] =
			p->hash[kFix3HashSize + hash3Value] =
			p->hash[kFix4HashSize + hashValue] = p->pos;
		p->son[p->cyclicBufferPos] = curMatch;
		MOVE_POS
			}
	while (--num != 0);
}

void Hc3Zip_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
	do
	{
		SKIP_HEADER(3)
			HASH_ZIP_CALC;
		curMatch = p->hash[hashValue];
		p->hash[hashValue] = p->pos;
		p->son[p->cyclicBufferPos] = curMatch;
		MOVE_POS
			}
	while (--num != 0);
}

void MatchFinder_CreateVTable(CMatchFinder *p, IMatchFinder *vTable)
{
	vTable->Init = (Mf_Init_Func)MatchFinder_Init;
	vTable->GetIndexByte = (Mf_GetIndexByte_Func)MatchFinder_GetIndexByte;
	vTable->GetNumAvailableBytes = (Mf_GetNumAvailableBytes_Func)MatchFinder_GetNumAvailableBytes;
	vTable->GetPointerToCurrentPos = (Mf_GetPointerToCurrentPos_Func)MatchFinder_GetPointerToCurrentPos;
	if (!p->btMode)
	{
		vTable->GetMatches = (Mf_GetMatches_Func)Hc4_MatchFinder_GetMatches;
		vTable->Skip = (Mf_Skip_Func)Hc4_MatchFinder_Skip;
	}
	else if (p->numHashBytes == 2)
	{
		vTable->GetMatches = (Mf_GetMatches_Func)Bt2_MatchFinder_GetMatches;
		vTable->Skip = (Mf_Skip_Func)Bt2_MatchFinder_Skip;
	}
	else if (p->numHashBytes == 3)
	{
		vTable->GetMatches = (Mf_GetMatches_Func)Bt3_MatchFinder_GetMatches;
		vTable->Skip = (Mf_Skip_Func)Bt3_MatchFinder_Skip;
	}
	else
	{
		vTable->GetMatches = (Mf_GetMatches_Func)Bt4_MatchFinder_GetMatches;
		vTable->Skip = (Mf_Skip_Func)Bt4_MatchFinder_Skip;
	}
}