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  1. /* LzFind.c -- Match finder for LZ algorithms
  2. 2008-10-04 : Igor Pavlov : Public domain */
  3.  
  4. #include <string.h>
  5.  
  6. #include "LzFind.h"
  7. #include "LzHash.h"
  8.  
  9. #define kEmptyHashValue 0
  10. #define kMaxValForNormalize ((UInt32)0xFFFFFFFF)
  11. #define kNormalizeStepMin (1u << 10) /* it must be power of 2 */ /*MAB 1u */
  12. #define kNormalizeMask (~(kNormalizeStepMin - 1))
  13. #define kMaxHistorySize ((UInt32)3 << 30)
  14.  
  15. #define kStartMaxLen 3
  16.  
  17. static void LzInWindow_Free(CMatchFinder *p, ISzAlloc *alloc)
  18. {
  19.   if (!p->directInput)
  20.   {
  21.     alloc->Free(alloc, p->bufferBase);
  22.     p->bufferBase = 0;
  23.   }
  24. }
  25.  
  26. /* keepSizeBefore + keepSizeAfter + keepSizeReserv must be < 4G) */
  27.  
  28. static int LzInWindow_Create(CMatchFinder *p, UInt32 keepSizeReserv, ISzAlloc *alloc)
  29. {
  30.   UInt32 blockSize = p->keepSizeBefore + p->keepSizeAfter + keepSizeReserv;
  31.   if (p->directInput)
  32.   {
  33.     p->blockSize = blockSize;
  34.     return 1;
  35.   }
  36.   if (p->bufferBase == 0 || p->blockSize != blockSize)
  37.   {
  38.     LzInWindow_Free(p, alloc);
  39.     p->blockSize = blockSize;
  40.     p->bufferBase = (Byte *)alloc->Alloc(alloc, (size_t)blockSize);
  41.   }
  42.   return (p->bufferBase != 0);
  43. }
  44.  
  45. Byte *MatchFinder_GetPointerToCurrentPos(CMatchFinder *p) { return p->buffer; }
  46.  
  47. /*MAB: static added, index replaced by idx to avoid shadowing a global variable */
  48. static
  49. Byte MatchFinder_GetIndexByte(CMatchFinder *p, Int32 idx) { return p->buffer[idx]; }
  50.  
  51. /*MAB: static added */
  52. static
  53. UInt32 MatchFinder_GetNumAvailableBytes(CMatchFinder *p) { return p->streamPos - p->pos; }
  54.  
  55. void MatchFinder_ReduceOffsets(CMatchFinder *p, UInt32 subValue)
  56. {
  57.   p->posLimit -= subValue;
  58.   p->pos -= subValue;
  59.   p->streamPos -= subValue;
  60. }
  61.  
  62. static void MatchFinder_ReadBlock(CMatchFinder *p)
  63. {
  64.   if (p->streamEndWasReached || p->result != SZ_OK)
  65.     return;
  66.   for (;;)
  67.   {
  68.     Byte *dest = p->buffer + (p->streamPos - p->pos);
  69.     size_t size = (size_t)(p->bufferBase + p->blockSize - dest);
  70.     if (size == 0)
  71.       return;
  72.     p->result = p->stream->Read(p->stream, dest, &size);
  73.     if (p->result != SZ_OK)
  74.       return;
  75.     if (size == 0)
  76.     {
  77.       p->streamEndWasReached = 1;
  78.       return;
  79.     }
  80.     p->streamPos += (UInt32)size;
  81.     if (p->streamPos - p->pos > p->keepSizeAfter)
  82.       return;
  83.   }
  84. }
  85.  
  86. void MatchFinder_MoveBlock(CMatchFinder *p)
  87. {
  88.   memmove(p->bufferBase,
  89.     p->buffer - p->keepSizeBefore,
  90.     (size_t)(p->streamPos - p->pos + p->keepSizeBefore));
  91.   p->buffer = p->bufferBase + p->keepSizeBefore;
  92. }
  93.  
  94. int MatchFinder_NeedMove(CMatchFinder *p)
  95. {
  96.   /* if (p->streamEndWasReached) return 0; */
  97.   return ((size_t)(p->bufferBase + p->blockSize - p->buffer) <= p->keepSizeAfter);
  98. }
  99.  
  100. void MatchFinder_ReadIfRequired(CMatchFinder *p)
  101. {
  102.   if (p->streamEndWasReached)
  103.     return;
  104.   if (p->keepSizeAfter >= p->streamPos - p->pos)
  105.     MatchFinder_ReadBlock(p);
  106. }
  107.  
  108. static void MatchFinder_CheckAndMoveAndRead(CMatchFinder *p)
  109. {
  110.   if (MatchFinder_NeedMove(p))
  111.     MatchFinder_MoveBlock(p);
  112.   MatchFinder_ReadBlock(p);
  113. }
  114.  
  115. static void MatchFinder_SetDefaultSettings(CMatchFinder *p)
  116. {
  117.   p->cutValue = 32;
  118.   p->btMode = 1;
  119.   p->numHashBytes = 4;
  120.   /* p->skipModeBits = 0; */
  121.   p->directInput = 0;
  122.   p->bigHash = 0;
  123. }
  124.  
  125. #define kCrcPoly 0xEDB88320
  126.  
  127. void MatchFinder_Construct(CMatchFinder *p)
  128. {
  129.   UInt32 i;
  130.   p->bufferBase = 0;
  131.   p->directInput = 0;
  132.   p->hash = 0;
  133.   MatchFinder_SetDefaultSettings(p);
  134.  
  135.   for (i = 0; i < 256; i++)
  136.   {
  137.     UInt32 r = i;
  138.     int j;
  139.     for (j = 0; j < 8; j++)
  140.       r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
  141.     p->crc[i] = r;
  142.   }
  143. }
  144.  
  145. static void MatchFinder_FreeThisClassMemory(CMatchFinder *p, ISzAlloc *alloc)
  146. {
  147.   alloc->Free(alloc, p->hash);
  148.   p->hash = 0;
  149. }
  150.  
  151. void MatchFinder_Free(CMatchFinder *p, ISzAlloc *alloc)
  152. {
  153.   MatchFinder_FreeThisClassMemory(p, alloc);
  154.   LzInWindow_Free(p, alloc);
  155. }
  156.  
  157. static CLzRef* AllocRefs(UInt32 num, ISzAlloc *alloc)
  158. {
  159.   size_t sizeInBytes = (size_t)num * sizeof(CLzRef);
  160.   if (sizeInBytes / sizeof(CLzRef) != num)
  161.     return 0;
  162.   return (CLzRef *)alloc->Alloc(alloc, sizeInBytes);
  163. }
  164.  
  165. int MatchFinder_Create(CMatchFinder *p, UInt32 historySize,
  166.     UInt32 keepAddBufferBefore, UInt32 matchMaxLen, UInt32 keepAddBufferAfter,
  167.     ISzAlloc *alloc)
  168. {
  169.   UInt32 sizeReserv;
  170.   if (historySize > kMaxHistorySize)
  171.   {
  172.     MatchFinder_Free(p, alloc);
  173.     return 0;
  174.   }
  175.   sizeReserv = historySize >> 1;
  176.   if (historySize > ((UInt32)2 << 30))
  177.     sizeReserv = historySize >> 2;
  178.   sizeReserv += (keepAddBufferBefore + matchMaxLen + keepAddBufferAfter) / 2 + (1 << 19);
  179.  
  180.   p->keepSizeBefore = historySize + keepAddBufferBefore + 1;
  181.   p->keepSizeAfter = matchMaxLen + keepAddBufferAfter;
  182.   /* we need one additional byte, since we use MoveBlock after pos++ and before dictionary using */
  183.   if (LzInWindow_Create(p, sizeReserv, alloc))
  184.   {
  185.     UInt32 newCyclicBufferSize = (historySize /* >> p->skipModeBits */) + 1;
  186.     UInt32 hs;
  187.     p->matchMaxLen = matchMaxLen;
  188.     {
  189.       p->fixedHashSize = 0;
  190.       if (p->numHashBytes == 2)
  191.         hs = (1 << 16) - 1;
  192.       else
  193.       {
  194.         hs = historySize - 1;
  195.         hs |= (hs >> 1);
  196.         hs |= (hs >> 2);
  197.         hs |= (hs >> 4);
  198.         hs |= (hs >> 8);
  199.         hs >>= 1;
  200.         /* hs >>= p->skipModeBits; */
  201.         hs |= 0xFFFF; /* don't change it! It's required for Deflate */
  202.         if (hs > (1 << 24))
  203.         {
  204.           if (p->numHashBytes == 3)
  205.             hs = (1 << 24) - 1;
  206.           else
  207.             hs >>= 1;
  208.         }
  209.       }
  210.       p->hashMask = hs;
  211.       hs++;
  212.       if (p->numHashBytes > 2) p->fixedHashSize += kHash2Size;
  213.       if (p->numHashBytes > 3) p->fixedHashSize += kHash3Size;
  214.       if (p->numHashBytes > 4) p->fixedHashSize += kHash4Size;
  215.       hs += p->fixedHashSize;
  216.     }
  217.  
  218.     {
  219.       UInt32 prevSize = p->hashSizeSum + p->numSons;
  220.       UInt32 newSize;
  221.       p->historySize = historySize;
  222.       p->hashSizeSum = hs;
  223.       p->cyclicBufferSize = newCyclicBufferSize;
  224.       p->numSons = (p->btMode ? newCyclicBufferSize * 2 : newCyclicBufferSize);
  225.       newSize = p->hashSizeSum + p->numSons;
  226.       if (p->hash != 0 && prevSize == newSize)
  227.         return 1;
  228.       MatchFinder_FreeThisClassMemory(p, alloc);
  229.       p->hash = AllocRefs(newSize, alloc);
  230.       if (p->hash != 0)
  231.       {
  232.         p->son = p->hash + p->hashSizeSum;
  233.         return 1;
  234.       }
  235.     }
  236.   }
  237.   MatchFinder_Free(p, alloc);
  238.   return 0;
  239. }
  240.  
  241. static void MatchFinder_SetLimits(CMatchFinder *p)
  242. {
  243.   UInt32 limit = kMaxValForNormalize - p->pos;
  244.   UInt32 limit2 = p->cyclicBufferSize - p->cyclicBufferPos;
  245.   if (limit2 < limit)
  246.     limit = limit2;
  247.   limit2 = p->streamPos - p->pos;
  248.   if (limit2 <= p->keepSizeAfter)
  249.   {
  250.     if (limit2 > 0)
  251.       limit2 = 1;
  252.   }
  253.   else
  254.     limit2 -= p->keepSizeAfter;
  255.   if (limit2 < limit)
  256.     limit = limit2;
  257.   {
  258.     UInt32 lenLimit = p->streamPos - p->pos;
  259.     if (lenLimit > p->matchMaxLen)
  260.       lenLimit = p->matchMaxLen;
  261.     p->lenLimit = lenLimit;
  262.   }
  263.   p->posLimit = p->pos + limit;
  264. }
  265.  
  266. void MatchFinder_Init(CMatchFinder *p)
  267. {
  268.   UInt32 i;
  269.   for (i = 0; i < p->hashSizeSum; i++)
  270.     p->hash[i] = kEmptyHashValue;
  271.   p->cyclicBufferPos = 0;
  272.   p->buffer = p->bufferBase;
  273.   p->pos = p->streamPos = p->cyclicBufferSize;
  274.   p->result = SZ_OK;
  275.   p->streamEndWasReached = 0;
  276.   MatchFinder_ReadBlock(p);
  277.   MatchFinder_SetLimits(p);
  278. }
  279.  
  280. static UInt32 MatchFinder_GetSubValue(CMatchFinder *p)
  281. {
  282.   return (p->pos - p->historySize - 1) & kNormalizeMask;
  283. }
  284.  
  285. void MatchFinder_Normalize3(UInt32 subValue, CLzRef *items, UInt32 numItems)
  286. {
  287.   UInt32 i;
  288.   for (i = 0; i < numItems; i++)
  289.   {
  290.     UInt32 value = items[i];
  291.     if (value <= subValue)
  292.       value = kEmptyHashValue;
  293.     else
  294.       value -= subValue;
  295.     items[i] = value;
  296.   }
  297. }
  298.  
  299. static void MatchFinder_Normalize(CMatchFinder *p)
  300. {
  301.   UInt32 subValue = MatchFinder_GetSubValue(p);
  302.   MatchFinder_Normalize3(subValue, p->hash, p->hashSizeSum + p->numSons);
  303.   MatchFinder_ReduceOffsets(p, subValue);
  304. }
  305.  
  306. static void MatchFinder_CheckLimits(CMatchFinder *p)
  307. {
  308.   if (p->pos == kMaxValForNormalize)
  309.     MatchFinder_Normalize(p);
  310.  
  311.   if (!p->streamEndWasReached && p->keepSizeAfter == p->streamPos - p->pos)
  312.     MatchFinder_CheckAndMoveAndRead(p);
  313.   if (p->cyclicBufferPos == p->cyclicBufferSize)
  314.     p->cyclicBufferPos = 0;
  315.   MatchFinder_SetLimits(p);
  316. }
  317.  
  318. static UInt32 * Hc_GetMatchesSpec(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
  319.     UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue,
  320.     UInt32 *distances, UInt32 maxLen)
  321. {
  322.   son[_cyclicBufferPos] = curMatch;
  323.   for (;;)
  324.   {
  325.     UInt32 delta = pos - curMatch;
  326.     if (cutValue-- == 0 || delta >= _cyclicBufferSize)
  327.       return distances;
  328.     {
  329.       const Byte *pb = cur - delta;
  330.       curMatch = son[_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)];
  331.       if (pb[maxLen] == cur[maxLen] && *pb == *cur)
  332.       {
  333.         UInt32 len = 0;
  334.         while (++len != lenLimit)
  335.           if (pb[len] != cur[len])
  336.             break;
  337.         if (maxLen < len)
  338.         {
  339.           *distances++ = maxLen = len;
  340.           *distances++ = delta - 1;
  341.           if (len == lenLimit)
  342.             return distances;
  343.         }
  344.       }
  345.     }
  346.   }
  347. }
  348.  
  349. UInt32 * GetMatchesSpec1(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
  350.     UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue,
  351.     UInt32 *distances, UInt32 maxLen)
  352. {
  353.   CLzRef *ptr0 = son + (_cyclicBufferPos << 1) + 1;
  354.   CLzRef *ptr1 = son + (_cyclicBufferPos << 1);
  355.   UInt32 len0 = 0, len1 = 0;
  356.   for (;;)
  357.   {
  358.     UInt32 delta = pos - curMatch;
  359.     if (cutValue-- == 0 || delta >= _cyclicBufferSize)
  360.     {
  361.       *ptr0 = *ptr1 = kEmptyHashValue;
  362.       return distances;
  363.     }
  364.     {
  365.       CLzRef *pair = son + ((_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
  366.       const Byte *pb = cur - delta;
  367.       UInt32 len = (len0 < len1 ? len0 : len1);
  368.       if (pb[len] == cur[len])
  369.       {
  370.         if (++len != lenLimit && pb[len] == cur[len])
  371.           while (++len != lenLimit)
  372.             if (pb[len] != cur[len])
  373.               break;
  374.         if (maxLen < len)
  375.         {
  376.           *distances++ = maxLen = len;
  377.           *distances++ = delta - 1;
  378.           if (len == lenLimit)
  379.           {
  380.             *ptr1 = pair[0];
  381.             *ptr0 = pair[1];
  382.             return distances;
  383.           }
  384.         }
  385.       }
  386.       if (pb[len] < cur[len])
  387.       {
  388.         *ptr1 = curMatch;
  389.         ptr1 = pair + 1;
  390.         curMatch = *ptr1;
  391.         len1 = len;
  392.       }
  393.       else
  394.       {
  395.         *ptr0 = curMatch;
  396.         ptr0 = pair;
  397.         curMatch = *ptr0;
  398.         len0 = len;
  399.       }
  400.     }
  401.   }
  402. }
  403.  
  404. static void SkipMatchesSpec(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
  405.     UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue)
  406. {
  407.   CLzRef *ptr0 = son + (_cyclicBufferPos << 1) + 1;
  408.   CLzRef *ptr1 = son + (_cyclicBufferPos << 1);
  409.   UInt32 len0 = 0, len1 = 0;
  410.   for (;;)
  411.   {
  412.     UInt32 delta = pos - curMatch;
  413.     if (cutValue-- == 0 || delta >= _cyclicBufferSize)
  414.     {
  415.       *ptr0 = *ptr1 = kEmptyHashValue;
  416.       return;
  417.     }
  418.     {
  419.       CLzRef *pair = son + ((_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
  420.       const Byte *pb = cur - delta;
  421.       UInt32 len = (len0 < len1 ? len0 : len1);
  422.       if (pb[len] == cur[len])
  423.       {
  424.         while (++len != lenLimit)
  425.           if (pb[len] != cur[len])
  426.             break;
  427.         {
  428.           if (len == lenLimit)
  429.           {
  430.             *ptr1 = pair[0];
  431.             *ptr0 = pair[1];
  432.             return;
  433.           }
  434.         }
  435.       }
  436.       if (pb[len] < cur[len])
  437.       {
  438.         *ptr1 = curMatch;
  439.         ptr1 = pair + 1;
  440.         curMatch = *ptr1;
  441.         len1 = len;
  442.       }
  443.       else
  444.       {
  445.         *ptr0 = curMatch;
  446.         ptr0 = pair;
  447.         curMatch = *ptr0;
  448.         len0 = len;
  449.       }
  450.     }
  451.   }
  452. }
  453.  
  454. #define MOVE_POS \
  455.   ++p->cyclicBufferPos; \
  456.   p->buffer++; \
  457.   if (++p->pos == p->posLimit) MatchFinder_CheckLimits(p);
  458.  
  459. #define MOVE_POS_RET MOVE_POS return offset;
  460.  
  461. static void MatchFinder_MovePos(CMatchFinder *p) { MOVE_POS; }
  462.  
  463. #define GET_MATCHES_HEADER2(minLen, ret_op) \
  464.   UInt32 lenLimit; UInt32 hashValue; const Byte *cur; UInt32 curMatch; \
  465.   lenLimit = p->lenLimit; { if (lenLimit < minLen) { MatchFinder_MovePos(p); ret_op; }} \
  466.   cur = p->buffer;
  467.  
  468. #define GET_MATCHES_HEADER(minLen) GET_MATCHES_HEADER2(minLen, return 0)
  469. #define SKIP_HEADER(minLen)        GET_MATCHES_HEADER2(minLen, continue)
  470.  
  471. #define MF_PARAMS(p) p->pos, p->buffer, p->son, p->cyclicBufferPos, p->cyclicBufferSize, p->cutValue
  472.  
  473. #define GET_MATCHES_FOOTER(offset, maxLen) \
  474.   offset = (UInt32)(GetMatchesSpec1(lenLimit, curMatch, MF_PARAMS(p), \
  475.   distances + offset, maxLen) - distances); MOVE_POS_RET;
  476.  
  477. #define SKIP_FOOTER \
  478.   SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p)); MOVE_POS;
  479.  
  480. static UInt32 Bt2_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
  481. {
  482.   UInt32 offset;
  483.   GET_MATCHES_HEADER(2)
  484.   HASH2_CALC;
  485.   curMatch = p->hash[hashValue];
  486.   p->hash[hashValue] = p->pos;
  487.   offset = 0;
  488.   GET_MATCHES_FOOTER(offset, 1)
  489. }
  490.  
  491. UInt32 Bt3Zip_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
  492. {
  493.   UInt32 offset;
  494.   GET_MATCHES_HEADER(3)
  495.   HASH_ZIP_CALC;
  496.   curMatch = p->hash[hashValue];
  497.   p->hash[hashValue] = p->pos;
  498.   offset = 0;
  499.   GET_MATCHES_FOOTER(offset, 2)
  500. }
  501.  
  502. static UInt32 Bt3_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
  503. {
  504.   UInt32 hash2Value, delta2, maxLen, offset;
  505.   GET_MATCHES_HEADER(3)
  506.  
  507.   HASH3_CALC;
  508.  
  509.   delta2 = p->pos - p->hash[hash2Value];
  510.   curMatch = p->hash[kFix3HashSize + hashValue];
  511.  
  512.   p->hash[hash2Value] =
  513.   p->hash[kFix3HashSize + hashValue] = p->pos;
  514.  
  515.  
  516.   maxLen = 2;
  517.   offset = 0;
  518.   if (delta2 < p->cyclicBufferSize && *(cur - delta2) == *cur)
  519.   {
  520.     for (; maxLen != lenLimit; maxLen++)
  521.       if (cur[(ptrdiff_t)maxLen - (ptrdiff_t)delta2] != cur[maxLen]) /*MAB second casts (ptrdiff_t)*/
  522.         break;
  523.     distances[0] = maxLen;
  524.     distances[1] = delta2 - 1;
  525.     offset = 2;
  526.     if (maxLen == lenLimit)
  527.     {
  528.       SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p));
  529.       MOVE_POS_RET;
  530.     }
  531.   }
  532.   GET_MATCHES_FOOTER(offset, maxLen)
  533. }
  534.  
  535. static UInt32 Bt4_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
  536. {
  537.   UInt32 hash2Value, hash3Value, delta2, delta3, maxLen, offset;
  538.   GET_MATCHES_HEADER(4)
  539.  
  540.   HASH4_CALC;
  541.  
  542.   delta2 = p->pos - p->hash[                hash2Value];
  543.   delta3 = p->pos - p->hash[kFix3HashSize + hash3Value];
  544.   curMatch = p->hash[kFix4HashSize + hashValue];
  545.  
  546.   p->hash[                hash2Value] =
  547.   p->hash[kFix3HashSize + hash3Value] =
  548.   p->hash[kFix4HashSize + hashValue] = p->pos;
  549.  
  550.   maxLen = 1;
  551.   offset = 0;
  552.   if (delta2 < p->cyclicBufferSize && *(cur - delta2) == *cur)
  553.   {
  554.     distances[0] = maxLen = 2;
  555.     distances[1] = delta2 - 1;
  556.     offset = 2;
  557.   }
  558.   if (delta2 != delta3 && delta3 < p->cyclicBufferSize && *(cur - delta3) == *cur)
  559.   {
  560.     maxLen = 3;
  561.     distances[offset + 1] = delta3 - 1;
  562.     offset += 2;
  563.     delta2 = delta3;
  564.   }
  565.   if (offset != 0)
  566.   {
  567.     for (; maxLen != lenLimit; maxLen++)
  568.       if (cur[(ptrdiff_t)maxLen - (ptrdiff_t)delta2] != cur[maxLen]) /*MAB casts second (ptrdiff_t)*/
  569.         break;
  570.     distances[offset - 2] = maxLen;
  571.     if (maxLen == lenLimit)
  572.     {
  573.       SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p));
  574.       MOVE_POS_RET;
  575.     }
  576.   }
  577.   if (maxLen < 3)
  578.     maxLen = 3;
  579.   GET_MATCHES_FOOTER(offset, maxLen)
  580. }
  581.  
  582. static UInt32 Hc4_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
  583. {
  584.   UInt32 hash2Value, hash3Value, delta2, delta3, maxLen, offset;
  585.   GET_MATCHES_HEADER(4)
  586.  
  587.   HASH4_CALC;
  588.  
  589.   delta2 = p->pos - p->hash[                hash2Value];
  590.   delta3 = p->pos - p->hash[kFix3HashSize + hash3Value];
  591.   curMatch = p->hash[kFix4HashSize + hashValue];
  592.  
  593.   p->hash[                hash2Value] =
  594.   p->hash[kFix3HashSize + hash3Value] =
  595.   p->hash[kFix4HashSize + hashValue] = p->pos;
  596.  
  597.   maxLen = 1;
  598.   offset = 0;
  599.   if (delta2 < p->cyclicBufferSize && *(cur - delta2) == *cur)
  600.   {
  601.     distances[0] = maxLen = 2;
  602.     distances[1] = delta2 - 1;
  603.     offset = 2;
  604.   }
  605.   if (delta2 != delta3 && delta3 < p->cyclicBufferSize && *(cur - delta3) == *cur)
  606.   {
  607.     maxLen = 3;
  608.     distances[offset + 1] = delta3 - 1;
  609.     offset += 2;
  610.     delta2 = delta3;
  611.   }
  612.   if (offset != 0)
  613.   {
  614.     for (; maxLen != lenLimit; maxLen++)
  615.       if (cur[(ptrdiff_t)maxLen - (ptrdiff_t)delta2] != cur[maxLen]) /*MAB casts second (ptrdiff_t) */
  616.         break;
  617.  
  618.     distances[offset - 2] = maxLen;
  619.     if (maxLen == lenLimit)
  620.     {
  621.       p->son[p->cyclicBufferPos] = curMatch;
  622.       MOVE_POS_RET;
  623.     }
  624.   }
  625.   if (maxLen < 3)
  626.     maxLen = 3;
  627.   offset = (UInt32)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
  628.     distances + offset, maxLen) - (distances));
  629.   MOVE_POS_RET
  630. }
  631.  
  632. UInt32 Hc3Zip_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
  633. {
  634.   UInt32 offset;
  635.   GET_MATCHES_HEADER(3)
  636.   HASH_ZIP_CALC;
  637.   curMatch = p->hash[hashValue];
  638.   p->hash[hashValue] = p->pos;
  639.   offset = (UInt32)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
  640.     distances, 2) - (distances));
  641.   MOVE_POS_RET
  642. }
  643.  
  644. static void Bt2_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
  645. {
  646.   do
  647.   {
  648.     SKIP_HEADER(2)
  649.     HASH2_CALC;
  650.     curMatch = p->hash[hashValue];
  651.     p->hash[hashValue] = p->pos;
  652.     SKIP_FOOTER
  653.   }
  654.   while (--num != 0);
  655. }
  656.  
  657. void Bt3Zip_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
  658. {
  659.   do
  660.   {
  661.     SKIP_HEADER(3)
  662.     HASH_ZIP_CALC;
  663.     curMatch = p->hash[hashValue];
  664.     p->hash[hashValue] = p->pos;
  665.     SKIP_FOOTER
  666.   }
  667.   while (--num != 0);
  668. }
  669.  
  670. static void Bt3_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
  671. {
  672.   do
  673.   {
  674.     UInt32 hash2Value;
  675.     SKIP_HEADER(3)
  676.     HASH3_CALC;
  677.     curMatch = p->hash[kFix3HashSize + hashValue];
  678.     p->hash[hash2Value] =
  679.     p->hash[kFix3HashSize + hashValue] = p->pos;
  680.     SKIP_FOOTER
  681.   }
  682.   while (--num != 0);
  683. }
  684.  
  685. static void Bt4_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
  686. {
  687.   do
  688.   {
  689.     UInt32 hash2Value, hash3Value;
  690.     SKIP_HEADER(4)
  691.     HASH4_CALC;
  692.     curMatch = p->hash[kFix4HashSize + hashValue];
  693.     p->hash[                hash2Value] =
  694.     p->hash[kFix3HashSize + hash3Value] = p->pos;
  695.     p->hash[kFix4HashSize + hashValue] = p->pos;
  696.     SKIP_FOOTER
  697.   }
  698.   while (--num != 0);
  699. }
  700.  
  701. static void Hc4_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
  702. {
  703.   do
  704.   {
  705.     UInt32 hash2Value, hash3Value;
  706.     SKIP_HEADER(4)
  707.     HASH4_CALC;
  708.     curMatch = p->hash[kFix4HashSize + hashValue];
  709.     p->hash[                hash2Value] =
  710.     p->hash[kFix3HashSize + hash3Value] =
  711.     p->hash[kFix4HashSize + hashValue] = p->pos;
  712.     p->son[p->cyclicBufferPos] = curMatch;
  713.     MOVE_POS
  714.   }
  715.   while (--num != 0);
  716. }
  717.  
  718. void Hc3Zip_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
  719. {
  720.   do
  721.   {
  722.     SKIP_HEADER(3)
  723.     HASH_ZIP_CALC;
  724.     curMatch = p->hash[hashValue];
  725.     p->hash[hashValue] = p->pos;
  726.     p->son[p->cyclicBufferPos] = curMatch;
  727.     MOVE_POS
  728.   }
  729.   while (--num != 0);
  730. }
  731.  
  732. void MatchFinder_CreateVTable(CMatchFinder *p, IMatchFinder *vTable)
  733. {
  734.   vTable->Init = (Mf_Init_Func)MatchFinder_Init;
  735.   vTable->GetIndexByte = (Mf_GetIndexByte_Func)MatchFinder_GetIndexByte;
  736.   vTable->GetNumAvailableBytes = (Mf_GetNumAvailableBytes_Func)MatchFinder_GetNumAvailableBytes;
  737.   vTable->GetPointerToCurrentPos = (Mf_GetPointerToCurrentPos_Func)MatchFinder_GetPointerToCurrentPos;
  738.   if (!p->btMode)
  739.   {
  740.     vTable->GetMatches = (Mf_GetMatches_Func)Hc4_MatchFinder_GetMatches;
  741.     vTable->Skip = (Mf_Skip_Func)Hc4_MatchFinder_Skip;
  742.   }
  743.   else if (p->numHashBytes == 2)
  744.   {
  745.     vTable->GetMatches = (Mf_GetMatches_Func)Bt2_MatchFinder_GetMatches;
  746.     vTable->Skip = (Mf_Skip_Func)Bt2_MatchFinder_Skip;
  747.   }
  748.   else if (p->numHashBytes == 3)
  749.   {
  750.     vTable->GetMatches = (Mf_GetMatches_Func)Bt3_MatchFinder_GetMatches;
  751.     vTable->Skip = (Mf_Skip_Func)Bt3_MatchFinder_Skip;
  752.   }
  753.   else
  754.   {
  755.     vTable->GetMatches = (Mf_GetMatches_Func)Bt4_MatchFinder_GetMatches;
  756.     vTable->Skip = (Mf_Skip_Func)Bt4_MatchFinder_Skip;
  757.   }
  758. }
  759.