Subversion Repositories spk

/* 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;

  }

}