/* LzFind.c -- Match finder for LZ algorithms
2018-07-08 : Igor Pavlov : Public domain */

#include "Precomp.h"

#ifndef EFIAPI
  #include <string.h>
#endif

#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       (~(UInt32)(kNormalizeStepMin - 1))
#define kMaxHistorySize      ((UInt32)7 << 29)

#define kStartMaxLen  3

static void
LzInWindow_Free (
  CMatchFinder  *p,
  ISzAllocPtr   alloc
  )
{
  if (!p->directInput) {
    ISzAlloc_Free (alloc, p->bufferBase);
    p->bufferBase = NULL;
  }
}

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

static int
LzInWindow_Create (
  CMatchFinder  *p,
  UInt32        keepSizeReserv,
  ISzAllocPtr   alloc
  )
{
  UInt32  blockSize = p->keepSizeBefore + p->keepSizeAfter + keepSizeReserv;

  if (p->directInput) {
    p->blockSize = blockSize;
    return 1;
  }

  if (!p->bufferBase || (p->blockSize != blockSize)) {
    LzInWindow_Free (p, alloc);
    p->blockSize  = blockSize;
    p->bufferBase = (Byte *)ISzAlloc_Alloc (alloc, (size_t)blockSize);
  }

  return (p->bufferBase != NULL);
}

Byte *
MatchFinder_GetPointerToCurrentPos (
  CMatchFinder  *p
  )
{
  return p->buffer;
}

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;
  }

  /* We use (p->streamPos - p->pos) value. (p->streamPos < p->pos) is allowed. */

  if (p->directInput) {
    UInt32  curSize = 0xFFFFFFFF - (p->streamPos - p->pos);
    if (curSize > p->directInputRem) {
      curSize = (UInt32)p->directInputRem;
    }

    p->directInputRem -= curSize;
    p->streamPos      += curSize;
    if (p->directInputRem == 0) {
      p->streamEndWasReached = 1;
    }

    return;
  }

  for ( ; ;) {
    Byte    *dest = p->buffer + (p->streamPos - p->pos);
    size_t  size  = (p->bufferBase + p->blockSize - dest);
    if (size == 0) {
      return;
    }

    p->result = ISeqInStream_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->directInput) {
    return 0;
  }

  /* 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->bigHash      = 0;
}

#define kCrcPoly  0xEDB88320

void
MatchFinder_Construct (
  CMatchFinder  *p
  )
{
  unsigned  i;

  p->bufferBase       = NULL;
  p->directInput      = 0;
  p->hash             = NULL;
  p->expectedDataSize = (UInt64)(Int64)-1;
  MatchFinder_SetDefaultSettings (p);

  for (i = 0; i < 256; i++) {
    UInt32    r = (UInt32)i;
    unsigned  j;
    for (j = 0; j < 8; j++) {
      r = (r >> 1) ^ (kCrcPoly & ((UInt32)0 - (r & 1)));
    }

    p->crc[i] = r;
  }
}

static void
MatchFinder_FreeThisClassMemory (
  CMatchFinder  *p,
  ISzAllocPtr   alloc
  )
{
  ISzAlloc_Free (alloc, p->hash);
  p->hash = NULL;
}

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

static CLzRef *
AllocRefs (
  size_t       num,
  ISzAllocPtr  alloc
  )
{
  size_t  sizeInBytes = (size_t)num * sizeof (CLzRef);

  if (sizeInBytes / sizeof (CLzRef) != num) {
    return NULL;
  }

  return (CLzRef *)ISzAlloc_Alloc (alloc, sizeInBytes);
}

int
MatchFinder_Create (
  CMatchFinder  *p,
  UInt32        historySize,
  UInt32        keepAddBufferBefore,
  UInt32        matchMaxLen,
  UInt32        keepAddBufferAfter,
  ISzAllocPtr   alloc
  )
{
  UInt32  sizeReserv;

  if (historySize > kMaxHistorySize) {
    MatchFinder_Free (p, alloc);
    return 0;
  }

  sizeReserv = historySize >> 1;
  if (historySize >= ((UInt32)3 << 30)) {
    sizeReserv = historySize >> 3;
  } else 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 + 1;
    UInt32  hs;
    p->matchMaxLen = matchMaxLen;
    {
      p->fixedHashSize = 0;
      if (p->numHashBytes == 2) {
        hs = (1 << 16) - 1;
      } else {
        hs = historySize;
        if (hs > p->expectedDataSize) {
          hs = (UInt32)p->expectedDataSize;
        }

        if (hs != 0) {
          hs--;
        }

        hs  |= (hs >> 1);
        hs  |= (hs >> 2);
        hs  |= (hs >> 4);
        hs  |= (hs >> 8);
        hs >>= 1;
        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;
          }

          /* if (bigHash) mode, GetHeads4b() in LzFindMt.c needs (hs >= ((1 << 24) - 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;
    }

    {
      size_t  newSize;
      size_t  numSons;
      p->historySize      = historySize;
      p->hashSizeSum      = hs;
      p->cyclicBufferSize = newCyclicBufferSize;

      numSons = newCyclicBufferSize;
      if (p->btMode) {
        numSons <<= 1;
      }

      newSize = hs + numSons;

      if (p->hash && (p->numRefs == newSize)) {
        return 1;
      }

      MatchFinder_FreeThisClassMemory (p, alloc);
      p->numRefs = newSize;
      p->hash    = AllocRefs (newSize, alloc);

      if (p->hash) {
        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_LowHash (
  CMatchFinder  *p
  )
{
  size_t  i;
  CLzRef  *items   = p->hash;
  size_t  numItems = p->fixedHashSize;

  for (i = 0; i < numItems; i++) {
    items[i] = kEmptyHashValue;
  }
}

void
MatchFinder_Init_HighHash (
  CMatchFinder  *p
  )
{
  size_t  i;
  CLzRef  *items   = p->hash + p->fixedHashSize;
  size_t  numItems = (size_t)p->hashMask + 1;

  for (i = 0; i < numItems; i++) {
    items[i] = kEmptyHashValue;
  }
}

void
MatchFinder_Init_3 (
  CMatchFinder  *p,
  int           readData
  )
{
  p->cyclicBufferPos     = 0;
  p->buffer              = p->bufferBase;
  p->pos                 =
    p->streamPos         = p->cyclicBufferSize;
  p->result              = SZ_OK;
  p->streamEndWasReached = 0;

  if (readData) {
    MatchFinder_ReadBlock (p);
  }

  MatchFinder_SetLimits (p);
}

void
MatchFinder_Init (
  CMatchFinder  *p
  )
{
  MatchFinder_Init_HighHash (p);
  MatchFinder_Init_LowHash (p);
  MatchFinder_Init_3 (p, True);
}

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

void
MatchFinder_Normalize3 (
  UInt32  subValue,
  CLzRef  *items,
  size_t  numItems
  )
{
  size_t  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->numRefs);
  MatchFinder_ReduceOffsets (p, subValue);
}

MY_NO_INLINE
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);
}

/*
  (lenLimit > maxLen)
*/
MY_FORCE_INLINE
static UInt32 *
Hc_GetMatchesSpec (
  unsigned    lenLimit,
  UInt32      curMatch,
  UInt32      pos,
  const Byte  *cur,
  CLzRef      *son,
  UInt32      _cyclicBufferPos,
  UInt32      _cyclicBufferSize,
  UInt32      cutValue,
  UInt32      *distances,
  unsigned    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)
        {
          maxLen = len;
          *distances++ = len;
          *distances++ = delta - 1;
          if (len == lenLimit)
            return distances;
        }
      }
    }
  }
  */

  const Byte  *lim = cur + lenLimit;

  son[_cyclicBufferPos] = curMatch;
  do {
    UInt32  delta = pos - curMatch;
    if (delta >= _cyclicBufferSize) {
      break;
    }

    {
      ptrdiff_t  diff;
      curMatch = son[_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)];
      diff     = (ptrdiff_t)0 - delta;
      if (cur[maxLen] == cur[maxLen + diff]) {
        const Byte  *c = cur;
        while (*c == c[diff]) {
          if (++c == lim) {
            distances[0] = (UInt32)(lim - cur);
            distances[1] = delta - 1;
            return distances + 2;
          }
        }

        {
          unsigned  len = (unsigned)(c - cur);
          if (maxLen < len) {
            maxLen       = len;
            distances[0] = (UInt32)len;
            distances[1] = delta - 1;
            distances   += 2;
          }
        }
      }
    }
  } while (--cutValue);

  return distances;
}

MY_FORCE_INLINE
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 + ((size_t)_cyclicBufferPos << 1) + 1;
  CLzRef    *ptr1 = son + ((size_t)_cyclicBufferPos << 1);
  unsigned  len0 = 0, len1 = 0;

  for ( ; ;) {
    UInt32  delta = pos - curMatch;
    if ((cutValue-- == 0) || (delta >= _cyclicBufferSize)) {
      *ptr0 = *ptr1 = kEmptyHashValue;
      return distances;
    }

    {
      CLzRef      *pair = son + ((size_t)(_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
      const Byte  *pb   = cur - delta;
      unsigned    len   = (len0 < len1 ? len0 : len1);
      UInt32      pair0 = pair[0];
      if (pb[len] == cur[len]) {
        if ((++len != lenLimit) && (pb[len] == cur[len])) {
          while (++len != lenLimit) {
            if (pb[len] != cur[len]) {
              break;
            }
          }
        }

        if (maxLen < len) {
          maxLen       = (UInt32)len;
          *distances++ = (UInt32)len;
          *distances++ = delta - 1;
          if (len == lenLimit) {
            *ptr1 = pair0;
            *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 + ((size_t)_cyclicBufferPos << 1) + 1;
  CLzRef    *ptr1 = son + ((size_t)_cyclicBufferPos << 1);
  unsigned  len0 = 0, len1 = 0;

  for ( ; ;) {
    UInt32  delta = pos - curMatch;
    if ((cutValue-- == 0) || (delta >= _cyclicBufferSize)) {
      *ptr0 = *ptr1 = kEmptyHashValue;
      return;
    }

    {
      CLzRef      *pair = son + ((size_t)(_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
      const Byte  *pb   = cur - delta;
      unsigned    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 (UInt32)offset;

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

#define GET_MATCHES_HEADER2(minLen, ret_op) \
  unsigned lenLimit; UInt32 hv; const Byte *cur; UInt32 curMatch; \
  lenLimit = (unsigned)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 = (unsigned)(GetMatchesSpec1((UInt32)lenLimit, curMatch, MF_PARAMS(p), \
  distances + offset, (UInt32)maxLen) - distances); MOVE_POS_RET;

#define SKIP_FOOTER \
  SkipMatchesSpec((UInt32)lenLimit, curMatch, MF_PARAMS(p)); MOVE_POS;

#define UPDATE_maxLen  {\
    ptrdiff_t diff = (ptrdiff_t)0 - d2; \
    const Byte *c = cur + maxLen; \
    const Byte *lim = cur + lenLimit; \
    for (; c != lim; c++) if (*(c + diff) != *c) break; \
    maxLen = (unsigned)(c - cur); }

static UInt32
Bt2_MatchFinder_GetMatches (
  CMatchFinder  *p,
  UInt32        *distances
  )
{
  unsigned  offset;

  GET_MATCHES_HEADER (2)
  HASH2_CALC;
  curMatch    = p->hash[hv];
  p->hash[hv] = p->pos;
  offset      = 0;
  GET_MATCHES_FOOTER (offset, 1)
}

UInt32
Bt3Zip_MatchFinder_GetMatches (
  CMatchFinder  *p,
  UInt32        *distances
  )
{
  unsigned  offset;

  GET_MATCHES_HEADER (3)
  HASH_ZIP_CALC;
  curMatch    = p->hash[hv];
  p->hash[hv] = p->pos;
  offset      = 0;
  GET_MATCHES_FOOTER (offset, 2)
}

static UInt32
Bt3_MatchFinder_GetMatches (
  CMatchFinder  *p,
  UInt32        *distances
  )
{
  UInt32    h2, d2, pos;
  unsigned  maxLen, offset;
  UInt32    *hash;

  GET_MATCHES_HEADER (3)

  HASH3_CALC;

  hash = p->hash;
  pos  = p->pos;

  d2 = pos - hash[h2];

  curMatch = (hash + kFix3HashSize)[hv];

  hash[h2]                   = pos;
  (hash + kFix3HashSize)[hv] = pos;

  maxLen = 2;
  offset = 0;

  if ((d2 < p->cyclicBufferSize) && (*(cur - d2) == *cur)) {
    UPDATE_maxLen
      distances[0] = (UInt32)maxLen;
    distances[1] = d2 - 1;
    offset       = 2;
    if (maxLen == lenLimit) {
      SkipMatchesSpec ((UInt32)lenLimit, curMatch, MF_PARAMS (p));
      MOVE_POS_RET;
    }
  }

  GET_MATCHES_FOOTER (offset, maxLen)
}

static UInt32
Bt4_MatchFinder_GetMatches (
  CMatchFinder  *p,
  UInt32        *distances
  )
{
  UInt32    h2, h3, d2, d3, pos;
  unsigned  maxLen, offset;
  UInt32    *hash;

  GET_MATCHES_HEADER (4)

  HASH4_CALC;

  hash = p->hash;
  pos  = p->pos;

  d2 = pos - hash[h2];
  d3 = pos - (hash + kFix3HashSize)[h3];

  curMatch = (hash + kFix4HashSize)[hv];

  hash[h2]                   = pos;
  (hash + kFix3HashSize)[h3] = pos;
  (hash + kFix4HashSize)[hv] = pos;

  maxLen = 0;
  offset = 0;

  if ((d2 < p->cyclicBufferSize) && (*(cur - d2) == *cur)) {
    maxLen       = 2;
    distances[0] = 2;
    distances[1] = d2 - 1;
    offset       = 2;
  }

  if ((d2 != d3) && (d3 < p->cyclicBufferSize) && (*(cur - d3) == *cur)) {
    maxLen                        = 3;
    distances[(size_t)offset + 1] = d3 - 1;
    offset                       += 2;
    d2                            = d3;
  }

  if (offset != 0) {
    UPDATE_maxLen
      distances[(size_t)offset - 2] = (UInt32)maxLen;
    if (maxLen == lenLimit) {
      SkipMatchesSpec ((UInt32)lenLimit, curMatch, MF_PARAMS (p));
      MOVE_POS_RET;
    }
  }

  if (maxLen < 3) {
    maxLen = 3;
  }

  GET_MATCHES_FOOTER (offset, maxLen)
}

/*
static UInt32 Bt5_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
  UInt32 h2, h3, h4, d2, d3, d4, maxLen, offset, pos;
  UInt32 *hash;
  GET_MATCHES_HEADER(5)

  HASH5_CALC;

  hash = p->hash;
  pos = p->pos;

  d2 = pos - hash[                h2];
  d3 = pos - (hash + kFix3HashSize)[h3];
  d4 = pos - (hash + kFix4HashSize)[h4];

  curMatch = (hash + kFix5HashSize)[hv];

  hash[                h2] = pos;
  (hash + kFix3HashSize)[h3] = pos;
  (hash + kFix4HashSize)[h4] = pos;
  (hash + kFix5HashSize)[hv] = pos;

  maxLen = 0;
  offset = 0;

  if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
  {
    distances[0] = maxLen = 2;
    distances[1] = d2 - 1;
    offset = 2;
    if (*(cur - d2 + 2) == cur[2])
      distances[0] = maxLen = 3;
    else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    {
      distances[2] = maxLen = 3;
      distances[3] = d3 - 1;
      offset = 4;
      d2 = d3;
    }
  }
  else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
  {
    distances[0] = maxLen = 3;
    distances[1] = d3 - 1;
    offset = 2;
    d2 = d3;
  }

  if (d2 != d4 && d4 < p->cyclicBufferSize
      && *(cur - d4) == *cur
      && *(cur - d4 + 3) == *(cur + 3))
  {
    maxLen = 4;
    distances[(size_t)offset + 1] = d4 - 1;
    offset += 2;
    d2 = d4;
  }

  if (offset != 0)
  {
    UPDATE_maxLen
    distances[(size_t)offset - 2] = maxLen;
    if (maxLen == lenLimit)
    {
      SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p));
      MOVE_POS_RET;
    }
  }

  if (maxLen < 4)
    maxLen = 4;

  GET_MATCHES_FOOTER(offset, maxLen)
}
*/
static UInt32
Hc4_MatchFinder_GetMatches (
  CMatchFinder  *p,
  UInt32        *distances
  )
{
  UInt32    h2, h3, d2, d3, pos;
  unsigned  maxLen, offset;
  UInt32    *hash;

  GET_MATCHES_HEADER (4)

  HASH4_CALC;

  hash = p->hash;
  pos  = p->pos;

  d2 = pos - hash[h2];
  d3 = pos - (hash + kFix3HashSize)[h3];

  curMatch = (hash + kFix4HashSize)[hv];

  hash[h2]                   = pos;
  (hash + kFix3HashSize)[h3] = pos;
  (hash + kFix4HashSize)[hv] = pos;

  maxLen = 0;
  offset = 0;

  if ((d2 < p->cyclicBufferSize) && (*(cur - d2) == *cur)) {
    maxLen       = 2;
    distances[0] = 2;
    distances[1] = d2 - 1;
    offset       = 2;
  }

  if ((d2 != d3) && (d3 < p->cyclicBufferSize) && (*(cur - d3) == *cur)) {
    maxLen                        = 3;
    distances[(size_t)offset + 1] = d3 - 1;
    offset                       += 2;
    d2                            = d3;
  }

  if (offset != 0) {
    UPDATE_maxLen
      distances[(size_t)offset - 2] = (UInt32)maxLen;
    if (maxLen == lenLimit) {
      p->son[p->cyclicBufferPos] = curMatch;
      MOVE_POS_RET;
    }
  }

  if (maxLen < 3) {
    maxLen = 3;
  }

  offset = (unsigned)(Hc_GetMatchesSpec (
                        lenLimit,
                        curMatch,
                        MF_PARAMS (p),
                        distances + offset,
                        maxLen
                        ) - (distances));
  MOVE_POS_RET
}

/*
static UInt32 Hc5_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
{
  UInt32 h2, h3, h4, d2, d3, d4, maxLen, offset, pos
  UInt32 *hash;
  GET_MATCHES_HEADER(5)

  HASH5_CALC;

  hash = p->hash;
  pos = p->pos;

  d2 = pos - hash[                h2];
  d3 = pos - (hash + kFix3HashSize)[h3];
  d4 = pos - (hash + kFix4HashSize)[h4];

  curMatch = (hash + kFix5HashSize)[hv];

  hash[                h2] = pos;
  (hash + kFix3HashSize)[h3] = pos;
  (hash + kFix4HashSize)[h4] = pos;
  (hash + kFix5HashSize)[hv] = pos;

  maxLen = 0;
  offset = 0;

  if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
  {
    distances[0] = maxLen = 2;
    distances[1] = d2 - 1;
    offset = 2;
    if (*(cur - d2 + 2) == cur[2])
      distances[0] = maxLen = 3;
    else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    {
      distances[2] = maxLen = 3;
      distances[3] = d3 - 1;
      offset = 4;
      d2 = d3;
    }
  }
  else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
  {
    distances[0] = maxLen = 3;
    distances[1] = d3 - 1;
    offset = 2;
    d2 = d3;
  }

  if (d2 != d4 && d4 < p->cyclicBufferSize
      && *(cur - d4) == *cur
      && *(cur - d4 + 3) == *(cur + 3))
  {
    maxLen = 4;
    distances[(size_t)offset + 1] = d4 - 1;
    offset += 2;
    d2 = d4;
  }

  if (offset != 0)
  {
    UPDATE_maxLen
    distances[(size_t)offset - 2] = maxLen;
    if (maxLen == lenLimit)
    {
      p->son[p->cyclicBufferPos] = curMatch;
      MOVE_POS_RET;
    }
  }

  if (maxLen < 4)
    maxLen = 4;

  offset = (UInt32)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
      distances + offset, maxLen) - (distances));
  MOVE_POS_RET
}
*/
UInt32
Hc3Zip_MatchFinder_GetMatches (
  CMatchFinder  *p,
  UInt32        *distances
  )
{
  unsigned  offset;

  GET_MATCHES_HEADER (3)
  HASH_ZIP_CALC;
  curMatch    = p->hash[hv];
  p->hash[hv] = p->pos;
  offset      = (unsigned)(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[hv];
    p->hash[hv] = 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[hv];
    p->hash[hv] = p->pos;
    SKIP_FOOTER
  } while (--num != 0);
}

static void
Bt3_MatchFinder_Skip (
  CMatchFinder  *p,
  UInt32        num
  )
{
  do {
    UInt32  h2;
    UInt32  *hash;
    SKIP_HEADER (3)
    HASH3_CALC;
    hash                         = p->hash;
    curMatch                     = (hash + kFix3HashSize)[hv];
    hash[h2]                     =
      (hash + kFix3HashSize)[hv] = p->pos;
    SKIP_FOOTER
  } while (--num != 0);
}

static void
Bt4_MatchFinder_Skip (
  CMatchFinder  *p,
  UInt32        num
  )
{
  do {
    UInt32  h2, h3;
    UInt32  *hash;
    SKIP_HEADER (4)
    HASH4_CALC;
    hash                           = p->hash;
    curMatch                       = (hash + kFix4HashSize)[hv];
    hash[h2]                       =
      (hash + kFix3HashSize)[h3]   =
        (hash + kFix4HashSize)[hv] = p->pos;
    SKIP_FOOTER
  } while (--num != 0);
}

/*
static void Bt5_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
  do
  {
    UInt32 h2, h3, h4;
    UInt32 *hash;
    SKIP_HEADER(5)
    HASH5_CALC;
    hash = p->hash;
    curMatch = (hash + kFix5HashSize)[hv];
    hash[                h2] =
    (hash + kFix3HashSize)[h3] =
    (hash + kFix4HashSize)[h4] =
    (hash + kFix5HashSize)[hv] = p->pos;
    SKIP_FOOTER
  }
  while (--num != 0);
}
*/
static void
Hc4_MatchFinder_Skip (
  CMatchFinder  *p,
  UInt32        num
  )
{
  do {
    UInt32  h2, h3;
    UInt32  *hash;
    SKIP_HEADER (4)
    HASH4_CALC;
    hash                           = p->hash;
    curMatch                       = (hash + kFix4HashSize)[hv];
    hash[h2]                       =
      (hash + kFix3HashSize)[h3]   =
        (hash + kFix4HashSize)[hv] = p->pos;
    p->son[p->cyclicBufferPos]     = curMatch;
    MOVE_POS
  } while (--num != 0);
}

/*
static void Hc5_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
{
  do
  {
    UInt32 h2, h3, h4;
    UInt32 *hash;
    SKIP_HEADER(5)
    HASH5_CALC;
    hash = p->hash;
    curMatch = hash + kFix5HashSize)[hv];
    hash[                h2] =
    (hash + kFix3HashSize)[h3] =
    (hash + kFix4HashSize)[h4] =
    (hash + kFix5HashSize)[hv] = 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[hv];
    p->hash[hv]                = 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->GetNumAvailableBytes   = (Mf_GetNumAvailableBytes_Func)MatchFinder_GetNumAvailableBytes;
  vTable->GetPointerToCurrentPos = (Mf_GetPointerToCurrentPos_Func)MatchFinder_GetPointerToCurrentPos;
  if (!p->btMode) {
    /* if (p->numHashBytes <= 4) */
    {
      vTable->GetMatches = (Mf_GetMatches_Func)Hc4_MatchFinder_GetMatches;
      vTable->Skip       = (Mf_Skip_Func)Hc4_MatchFinder_Skip;
    }

    /*
    else
    {
      vTable->GetMatches = (Mf_GetMatches_Func)Hc5_MatchFinder_GetMatches;
      vTable->Skip = (Mf_Skip_Func)Hc5_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 {
    /* if (p->numHashBytes == 4) */
    vTable->GetMatches = (Mf_GetMatches_Func)Bt4_MatchFinder_GetMatches;
    vTable->Skip       = (Mf_Skip_Func)Bt4_MatchFinder_Skip;
  }

  /*
  else
  {
    vTable->GetMatches = (Mf_GetMatches_Func)Bt5_MatchFinder_GetMatches;
    vTable->Skip = (Mf_Skip_Func)Bt5_MatchFinder_Skip;
  }
  */
}