LzFind.c - duckstation - duckstation, but archived from the revision just before upstream changed it to a proprietary software project, this version is the libre one

LzFind.c (26194B)
      1 /* LzFind.c -- Match finder for LZ algorithms
      2 2018-07-08 : Igor Pavlov : Public domain */
      3 
      4 #include "Precomp.h"
      5 
      6 #include <string.h>
      7 
      8 #include "LzFind.h"
      9 #include "LzHash.h"
     10 
     11 #define kEmptyHashValue 0
     12 #define kMaxValForNormalize ((UInt32)0xFFFFFFFF)
     13 #define kNormalizeStepMin (1 << 10) /* it must be power of 2 */
     14 #define kNormalizeMask (~(UInt32)(kNormalizeStepMin - 1))
     15 #define kMaxHistorySize ((UInt32)7 << 29)
     16 
     17 #define kStartMaxLen 3
     18 
     19 static void LzInWindow_Free(CMatchFinder *p, ISzAllocPtr alloc)
     20 {
     21   if (!p->directInput)
     22   {
     23     ISzAlloc_Free(alloc, p->bufferBase);
     24     p->bufferBase = NULL;
     25   }
     26 }
     27 
     28 /* keepSizeBefore + keepSizeAfter + keepSizeReserv must be < 4G) */
     29 
     30 static int LzInWindow_Create(CMatchFinder *p, UInt32 keepSizeReserv, ISzAllocPtr alloc)
     31 {
     32   UInt32 blockSize = p->keepSizeBefore + p->keepSizeAfter + keepSizeReserv;
     33   if (p->directInput)
     34   {
     35     p->blockSize = blockSize;
     36     return 1;
     37   }
     38   if (!p->bufferBase || p->blockSize != blockSize)
     39   {
     40     LzInWindow_Free(p, alloc);
     41     p->blockSize = blockSize;
     42     p->bufferBase = (Byte *)ISzAlloc_Alloc(alloc, (size_t)blockSize);
     43   }
     44   return (p->bufferBase != NULL);
     45 }
     46 
     47 Byte *MatchFinder_GetPointerToCurrentPos(CMatchFinder *p) { return p->buffer; }
     48 
     49 UInt32 MatchFinder_GetNumAvailableBytes(CMatchFinder *p) { return p->streamPos - p->pos; }
     50 
     51 void MatchFinder_ReduceOffsets(CMatchFinder *p, UInt32 subValue)
     52 {
     53   p->posLimit -= subValue;
     54   p->pos -= subValue;
     55   p->streamPos -= subValue;
     56 }
     57 
     58 static void MatchFinder_ReadBlock(CMatchFinder *p)
     59 {
     60   if (p->streamEndWasReached || p->result != SZ_OK)
     61     return;
     62 
     63   /* We use (p->streamPos - p->pos) value. (p->streamPos < p->pos) is allowed. */
     64 
     65   if (p->directInput)
     66   {
     67     UInt32 curSize = 0xFFFFFFFF - (p->streamPos - p->pos);
     68     if (curSize > p->directInputRem)
     69       curSize = (UInt32)p->directInputRem;
     70     p->directInputRem -= curSize;
     71     p->streamPos += curSize;
     72     if (p->directInputRem == 0)
     73       p->streamEndWasReached = 1;
     74     return;
     75   }
     76   
     77   for (;;)
     78   {
     79     Byte *dest = p->buffer + (p->streamPos - p->pos);
     80     size_t size = (p->bufferBase + p->blockSize - dest);
     81     if (size == 0)
     82       return;
     83 
     84     p->result = ISeqInStream_Read(p->stream, dest, &size);
     85     if (p->result != SZ_OK)
     86       return;
     87     if (size == 0)
     88     {
     89       p->streamEndWasReached = 1;
     90       return;
     91     }
     92     p->streamPos += (UInt32)size;
     93     if (p->streamPos - p->pos > p->keepSizeAfter)
     94       return;
     95   }
     96 }
     97 
     98 void MatchFinder_MoveBlock(CMatchFinder *p)
     99 {
    100   memmove(p->bufferBase,
    101       p->buffer - p->keepSizeBefore,
    102       (size_t)(p->streamPos - p->pos) + p->keepSizeBefore);
    103   p->buffer = p->bufferBase + p->keepSizeBefore;
    104 }
    105 
    106 int MatchFinder_NeedMove(CMatchFinder *p)
    107 {
    108   if (p->directInput)
    109     return 0;
    110   /* if (p->streamEndWasReached) return 0; */
    111   return ((size_t)(p->bufferBase + p->blockSize - p->buffer) <= p->keepSizeAfter);
    112 }
    113 
    114 void MatchFinder_ReadIfRequired(CMatchFinder *p)
    115 {
    116   if (p->streamEndWasReached)
    117     return;
    118   if (p->keepSizeAfter >= p->streamPos - p->pos)
    119     MatchFinder_ReadBlock(p);
    120 }
    121 
    122 static void MatchFinder_CheckAndMoveAndRead(CMatchFinder *p)
    123 {
    124   if (MatchFinder_NeedMove(p))
    125     MatchFinder_MoveBlock(p);
    126   MatchFinder_ReadBlock(p);
    127 }
    128 
    129 static void MatchFinder_SetDefaultSettings(CMatchFinder *p)
    130 {
    131   p->cutValue = 32;
    132   p->btMode = 1;
    133   p->numHashBytes = 4;
    134   p->bigHash = 0;
    135 }
    136 
    137 #define kCrcPoly 0xEDB88320
    138 
    139 void MatchFinder_Construct(CMatchFinder *p)
    140 {
    141   unsigned i;
    142   p->bufferBase = NULL;
    143   p->directInput = 0;
    144   p->hash = NULL;
    145   p->expectedDataSize = (UInt64)(Int64)-1;
    146   MatchFinder_SetDefaultSettings(p);
    147 
    148   for (i = 0; i < 256; i++)
    149   {
    150     UInt32 r = (UInt32)i;
    151     unsigned j;
    152     for (j = 0; j < 8; j++)
    153       r = (r >> 1) ^ (kCrcPoly & ((UInt32)0 - (r & 1)));
    154     p->crc[i] = r;
    155   }
    156 }
    157 
    158 static void MatchFinder_FreeThisClassMemory(CMatchFinder *p, ISzAllocPtr alloc)
    159 {
    160   ISzAlloc_Free(alloc, p->hash);
    161   p->hash = NULL;
    162 }
    163 
    164 void MatchFinder_Free(CMatchFinder *p, ISzAllocPtr alloc)
    165 {
    166   MatchFinder_FreeThisClassMemory(p, alloc);
    167   LzInWindow_Free(p, alloc);
    168 }
    169 
    170 static CLzRef* AllocRefs(size_t num, ISzAllocPtr alloc)
    171 {
    172   size_t sizeInBytes = (size_t)num * sizeof(CLzRef);
    173   if (sizeInBytes / sizeof(CLzRef) != num)
    174     return NULL;
    175   return (CLzRef *)ISzAlloc_Alloc(alloc, sizeInBytes);
    176 }
    177 
    178 int MatchFinder_Create(CMatchFinder *p, UInt32 historySize,
    179     UInt32 keepAddBufferBefore, UInt32 matchMaxLen, UInt32 keepAddBufferAfter,
    180     ISzAllocPtr alloc)
    181 {
    182   UInt32 sizeReserv;
    183   
    184   if (historySize > kMaxHistorySize)
    185   {
    186     MatchFinder_Free(p, alloc);
    187     return 0;
    188   }
    189   
    190   sizeReserv = historySize >> 1;
    191        if (historySize >= ((UInt32)3 << 30)) sizeReserv = historySize >> 3;
    192   else if (historySize >= ((UInt32)2 << 30)) sizeReserv = historySize >> 2;
    193   
    194   sizeReserv += (keepAddBufferBefore + matchMaxLen + keepAddBufferAfter) / 2 + (1 << 19);
    195 
    196   p->keepSizeBefore = historySize + keepAddBufferBefore + 1;
    197   p->keepSizeAfter = matchMaxLen + keepAddBufferAfter;
    198   
    199   /* we need one additional byte, since we use MoveBlock after pos++ and before dictionary using */
    200   
    201   if (LzInWindow_Create(p, sizeReserv, alloc))
    202   {
    203     UInt32 newCyclicBufferSize = historySize + 1;
    204     UInt32 hs;
    205     p->matchMaxLen = matchMaxLen;
    206     {
    207       p->fixedHashSize = 0;
    208       if (p->numHashBytes == 2)
    209         hs = (1 << 16) - 1;
    210       else
    211       {
    212         hs = historySize;
    213         if (hs > p->expectedDataSize)
    214           hs = (UInt32)p->expectedDataSize;
    215         if (hs != 0)
    216           hs--;
    217         hs |= (hs >> 1);
    218         hs |= (hs >> 2);
    219         hs |= (hs >> 4);
    220         hs |= (hs >> 8);
    221         hs >>= 1;
    222         hs |= 0xFFFF; /* don't change it! It's required for Deflate */
    223         if (hs > (1 << 24))
    224         {
    225           if (p->numHashBytes == 3)
    226             hs = (1 << 24) - 1;
    227           else
    228             hs >>= 1;
    229           /* if (bigHash) mode, GetHeads4b() in LzFindMt.c needs (hs >= ((1 << 24) - 1))) */
    230         }
    231       }
    232       p->hashMask = hs;
    233       hs++;
    234       if (p->numHashBytes > 2) p->fixedHashSize += kHash2Size;
    235       if (p->numHashBytes > 3) p->fixedHashSize += kHash3Size;
    236       if (p->numHashBytes > 4) p->fixedHashSize += kHash4Size;
    237       hs += p->fixedHashSize;
    238     }
    239 
    240     {
    241       size_t newSize;
    242       size_t numSons;
    243       p->historySize = historySize;
    244       p->hashSizeSum = hs;
    245       p->cyclicBufferSize = newCyclicBufferSize;
    246       
    247       numSons = newCyclicBufferSize;
    248       if (p->btMode)
    249         numSons <<= 1;
    250       newSize = hs + numSons;
    251 
    252       if (p->hash && p->numRefs == newSize)
    253         return 1;
    254       
    255       MatchFinder_FreeThisClassMemory(p, alloc);
    256       p->numRefs = newSize;
    257       p->hash = AllocRefs(newSize, alloc);
    258       
    259       if (p->hash)
    260       {
    261         p->son = p->hash + p->hashSizeSum;
    262         return 1;
    263       }
    264     }
    265   }
    266 
    267   MatchFinder_Free(p, alloc);
    268   return 0;
    269 }
    270 
    271 static void MatchFinder_SetLimits(CMatchFinder *p)
    272 {
    273   UInt32 limit = kMaxValForNormalize - p->pos;
    274   UInt32 limit2 = p->cyclicBufferSize - p->cyclicBufferPos;
    275   
    276   if (limit2 < limit)
    277     limit = limit2;
    278   limit2 = p->streamPos - p->pos;
    279   
    280   if (limit2 <= p->keepSizeAfter)
    281   {
    282     if (limit2 > 0)
    283       limit2 = 1;
    284   }
    285   else
    286     limit2 -= p->keepSizeAfter;
    287   
    288   if (limit2 < limit)
    289     limit = limit2;
    290   
    291   {
    292     UInt32 lenLimit = p->streamPos - p->pos;
    293     if (lenLimit > p->matchMaxLen)
    294       lenLimit = p->matchMaxLen;
    295     p->lenLimit = lenLimit;
    296   }
    297   p->posLimit = p->pos + limit;
    298 }
    299 
    300 
    301 void MatchFinder_Init_LowHash(CMatchFinder *p)
    302 {
    303   size_t i;
    304   CLzRef *items = p->hash;
    305   size_t numItems = p->fixedHashSize;
    306   for (i = 0; i < numItems; i++)
    307     items[i] = kEmptyHashValue;
    308 }
    309 
    310 
    311 void MatchFinder_Init_HighHash(CMatchFinder *p)
    312 {
    313   size_t i;
    314   CLzRef *items = p->hash + p->fixedHashSize;
    315   size_t numItems = (size_t)p->hashMask + 1;
    316   for (i = 0; i < numItems; i++)
    317     items[i] = kEmptyHashValue;
    318 }
    319 
    320 
    321 void MatchFinder_Init_3(CMatchFinder *p, int readData)
    322 {
    323   p->cyclicBufferPos = 0;
    324   p->buffer = p->bufferBase;
    325   p->pos =
    326   p->streamPos = p->cyclicBufferSize;
    327   p->result = SZ_OK;
    328   p->streamEndWasReached = 0;
    329   
    330   if (readData)
    331     MatchFinder_ReadBlock(p);
    332   
    333   MatchFinder_SetLimits(p);
    334 }
    335 
    336 
    337 void MatchFinder_Init(CMatchFinder *p)
    338 {
    339   MatchFinder_Init_HighHash(p);
    340   MatchFinder_Init_LowHash(p);
    341   MatchFinder_Init_3(p, True);
    342 }
    343 
    344   
    345 static UInt32 MatchFinder_GetSubValue(CMatchFinder *p)
    346 {
    347   return (p->pos - p->historySize - 1) & kNormalizeMask;
    348 }
    349 
    350 void MatchFinder_Normalize3(UInt32 subValue, CLzRef *items, size_t numItems)
    351 {
    352   size_t i;
    353   for (i = 0; i < numItems; i++)
    354   {
    355     UInt32 value = items[i];
    356     if (value <= subValue)
    357       value = kEmptyHashValue;
    358     else
    359       value -= subValue;
    360     items[i] = value;
    361   }
    362 }
    363 
    364 static void MatchFinder_Normalize(CMatchFinder *p)
    365 {
    366   UInt32 subValue = MatchFinder_GetSubValue(p);
    367   MatchFinder_Normalize3(subValue, p->hash, p->numRefs);
    368   MatchFinder_ReduceOffsets(p, subValue);
    369 }
    370 
    371 
    372 MY_NO_INLINE
    373 static void MatchFinder_CheckLimits(CMatchFinder *p)
    374 {
    375   if (p->pos == kMaxValForNormalize)
    376     MatchFinder_Normalize(p);
    377   if (!p->streamEndWasReached && p->keepSizeAfter == p->streamPos - p->pos)
    378     MatchFinder_CheckAndMoveAndRead(p);
    379   if (p->cyclicBufferPos == p->cyclicBufferSize)
    380     p->cyclicBufferPos = 0;
    381   MatchFinder_SetLimits(p);
    382 }
    383 
    384 
    385 /*
    386   (lenLimit > maxLen)
    387 */
    388 MY_FORCE_INLINE
    389 static UInt32 * Hc_GetMatchesSpec(unsigned lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
    390     UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue,
    391     UInt32 *distances, unsigned maxLen)
    392 {
    393   /*
    394   son[_cyclicBufferPos] = curMatch;
    395   for (;;)
    396   {
    397     UInt32 delta = pos - curMatch;
    398     if (cutValue-- == 0 || delta >= _cyclicBufferSize)
    399       return distances;
    400     {
    401       const Byte *pb = cur - delta;
    402       curMatch = son[_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)];
    403       if (pb[maxLen] == cur[maxLen] && *pb == *cur)
    404       {
    405         UInt32 len = 0;
    406         while (++len != lenLimit)
    407           if (pb[len] != cur[len])
    408             break;
    409         if (maxLen < len)
    410         {
    411           maxLen = len;
    412           *distances++ = len;
    413           *distances++ = delta - 1;
    414           if (len == lenLimit)
    415             return distances;
    416         }
    417       }
    418     }
    419   }
    420   */
    421 
    422   const Byte *lim = cur + lenLimit;
    423   son[_cyclicBufferPos] = curMatch;
    424   do
    425   {
    426     UInt32 delta = pos - curMatch;
    427     if (delta >= _cyclicBufferSize)
    428       break;
    429     {
    430       ptrdiff_t diff;
    431       curMatch = son[_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)];
    432       diff = (ptrdiff_t)0 - delta;
    433       if (cur[maxLen] == cur[maxLen + diff])
    434       {
    435         const Byte *c = cur;
    436         while (*c == c[diff])
    437         {
    438           if (++c == lim)
    439           {
    440             distances[0] = (UInt32)(lim - cur);
    441             distances[1] = delta - 1;
    442             return distances + 2;
    443           }
    444         }
    445         {
    446           unsigned len = (unsigned)(c - cur);
    447           if (maxLen < len)
    448           {
    449             maxLen = len;
    450             distances[0] = (UInt32)len;
    451             distances[1] = delta - 1;
    452             distances += 2;
    453           }
    454         }
    455       }
    456     }
    457   }
    458   while (--cutValue);
    459   
    460   return distances;
    461 }
    462 
    463 
    464 MY_FORCE_INLINE
    465 UInt32 * GetMatchesSpec1(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
    466     UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue,
    467     UInt32 *distances, UInt32 maxLen)
    468 {
    469   CLzRef *ptr0 = son + ((size_t)_cyclicBufferPos << 1) + 1;
    470   CLzRef *ptr1 = son + ((size_t)_cyclicBufferPos << 1);
    471   unsigned len0 = 0, len1 = 0;
    472   for (;;)
    473   {
    474     UInt32 delta = pos - curMatch;
    475     if (cutValue-- == 0 || delta >= _cyclicBufferSize)
    476     {
    477       *ptr0 = *ptr1 = kEmptyHashValue;
    478       return distances;
    479     }
    480     {
    481       CLzRef *pair = son + ((size_t)(_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
    482       const Byte *pb = cur - delta;
    483       unsigned len = (len0 < len1 ? len0 : len1);
    484       UInt32 pair0 = pair[0];
    485       if (pb[len] == cur[len])
    486       {
    487         if (++len != lenLimit && pb[len] == cur[len])
    488           while (++len != lenLimit)
    489             if (pb[len] != cur[len])
    490               break;
    491         if (maxLen < len)
    492         {
    493           maxLen = (UInt32)len;
    494           *distances++ = (UInt32)len;
    495           *distances++ = delta - 1;
    496           if (len == lenLimit)
    497           {
    498             *ptr1 = pair0;
    499             *ptr0 = pair[1];
    500             return distances;
    501           }
    502         }
    503       }
    504       if (pb[len] < cur[len])
    505       {
    506         *ptr1 = curMatch;
    507         ptr1 = pair + 1;
    508         curMatch = *ptr1;
    509         len1 = len;
    510       }
    511       else
    512       {
    513         *ptr0 = curMatch;
    514         ptr0 = pair;
    515         curMatch = *ptr0;
    516         len0 = len;
    517       }
    518     }
    519   }
    520 }
    521 
    522 static void SkipMatchesSpec(UInt32 lenLimit, UInt32 curMatch, UInt32 pos, const Byte *cur, CLzRef *son,
    523     UInt32 _cyclicBufferPos, UInt32 _cyclicBufferSize, UInt32 cutValue)
    524 {
    525   CLzRef *ptr0 = son + ((size_t)_cyclicBufferPos << 1) + 1;
    526   CLzRef *ptr1 = son + ((size_t)_cyclicBufferPos << 1);
    527   unsigned len0 = 0, len1 = 0;
    528   for (;;)
    529   {
    530     UInt32 delta = pos - curMatch;
    531     if (cutValue-- == 0 || delta >= _cyclicBufferSize)
    532     {
    533       *ptr0 = *ptr1 = kEmptyHashValue;
    534       return;
    535     }
    536     {
    537       CLzRef *pair = son + ((size_t)(_cyclicBufferPos - delta + ((delta > _cyclicBufferPos) ? _cyclicBufferSize : 0)) << 1);
    538       const Byte *pb = cur - delta;
    539       unsigned len = (len0 < len1 ? len0 : len1);
    540       if (pb[len] == cur[len])
    541       {
    542         while (++len != lenLimit)
    543           if (pb[len] != cur[len])
    544             break;
    545         {
    546           if (len == lenLimit)
    547           {
    548             *ptr1 = pair[0];
    549             *ptr0 = pair[1];
    550             return;
    551           }
    552         }
    553       }
    554       if (pb[len] < cur[len])
    555       {
    556         *ptr1 = curMatch;
    557         ptr1 = pair + 1;
    558         curMatch = *ptr1;
    559         len1 = len;
    560       }
    561       else
    562       {
    563         *ptr0 = curMatch;
    564         ptr0 = pair;
    565         curMatch = *ptr0;
    566         len0 = len;
    567       }
    568     }
    569   }
    570 }
    571 
    572 #define MOVE_POS \
    573   ++p->cyclicBufferPos; \
    574   p->buffer++; \
    575   if (++p->pos == p->posLimit) MatchFinder_CheckLimits(p);
    576 
    577 #define MOVE_POS_RET MOVE_POS return (UInt32)offset;
    578 
    579 static void MatchFinder_MovePos(CMatchFinder *p) { MOVE_POS; }
    580 
    581 #define GET_MATCHES_HEADER2(minLen, ret_op) \
    582   unsigned lenLimit; UInt32 hv; const Byte *cur; UInt32 curMatch; \
    583   lenLimit = (unsigned)p->lenLimit; { if (lenLimit < minLen) { MatchFinder_MovePos(p); ret_op; }} \
    584   cur = p->buffer;
    585 
    586 #define GET_MATCHES_HEADER(minLen) GET_MATCHES_HEADER2(minLen, return 0)
    587 #define SKIP_HEADER(minLen)        GET_MATCHES_HEADER2(minLen, continue)
    588 
    589 #define MF_PARAMS(p) p->pos, p->buffer, p->son, p->cyclicBufferPos, p->cyclicBufferSize, p->cutValue
    590 
    591 #define GET_MATCHES_FOOTER(offset, maxLen) \
    592   offset = (unsigned)(GetMatchesSpec1((UInt32)lenLimit, curMatch, MF_PARAMS(p), \
    593   distances + offset, (UInt32)maxLen) - distances); MOVE_POS_RET;
    594 
    595 #define SKIP_FOOTER \
    596   SkipMatchesSpec((UInt32)lenLimit, curMatch, MF_PARAMS(p)); MOVE_POS;
    597 
    598 #define UPDATE_maxLen { \
    599     ptrdiff_t diff = (ptrdiff_t)0 - d2; \
    600     const Byte *c = cur + maxLen; \
    601     const Byte *lim = cur + lenLimit; \
    602     for (; c != lim; c++) if (*(c + diff) != *c) break; \
    603     maxLen = (unsigned)(c - cur); }
    604 
    605 static UInt32 Bt2_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    606 {
    607   unsigned offset;
    608   GET_MATCHES_HEADER(2)
    609   HASH2_CALC;
    610   curMatch = p->hash[hv];
    611   p->hash[hv] = p->pos;
    612   offset = 0;
    613   GET_MATCHES_FOOTER(offset, 1)
    614 }
    615 
    616 UInt32 Bt3Zip_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    617 {
    618   unsigned offset;
    619   GET_MATCHES_HEADER(3)
    620   HASH_ZIP_CALC;
    621   curMatch = p->hash[hv];
    622   p->hash[hv] = p->pos;
    623   offset = 0;
    624   GET_MATCHES_FOOTER(offset, 2)
    625 }
    626 
    627 static UInt32 Bt3_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    628 {
    629   UInt32 h2, d2, pos;
    630   unsigned maxLen, offset;
    631   UInt32 *hash;
    632   GET_MATCHES_HEADER(3)
    633 
    634   HASH3_CALC;
    635 
    636   hash = p->hash;
    637   pos = p->pos;
    638 
    639   d2 = pos - hash[h2];
    640 
    641   curMatch = (hash + kFix3HashSize)[hv];
    642   
    643   hash[h2] = pos;
    644   (hash + kFix3HashSize)[hv] = pos;
    645 
    646   maxLen = 2;
    647   offset = 0;
    648 
    649   if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
    650   {
    651     UPDATE_maxLen
    652     distances[0] = (UInt32)maxLen;
    653     distances[1] = d2 - 1;
    654     offset = 2;
    655     if (maxLen == lenLimit)
    656     {
    657       SkipMatchesSpec((UInt32)lenLimit, curMatch, MF_PARAMS(p));
    658       MOVE_POS_RET;
    659     }
    660   }
    661   
    662   GET_MATCHES_FOOTER(offset, maxLen)
    663 }
    664 
    665 static UInt32 Bt4_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    666 {
    667   UInt32 h2, h3, d2, d3, pos;
    668   unsigned maxLen, offset;
    669   UInt32 *hash;
    670   GET_MATCHES_HEADER(4)
    671 
    672   HASH4_CALC;
    673 
    674   hash = p->hash;
    675   pos = p->pos;
    676 
    677   d2 = pos - hash                  [h2];
    678   d3 = pos - (hash + kFix3HashSize)[h3];
    679 
    680   curMatch = (hash + kFix4HashSize)[hv];
    681 
    682   hash                  [h2] = pos;
    683   (hash + kFix3HashSize)[h3] = pos;
    684   (hash + kFix4HashSize)[hv] = pos;
    685 
    686   maxLen = 0;
    687   offset = 0;
    688   
    689   if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
    690   {
    691     maxLen = 2;
    692     distances[0] = 2;
    693     distances[1] = d2 - 1;
    694     offset = 2;
    695   }
    696   
    697   if (d2 != d3 && d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    698   {
    699     maxLen = 3;
    700     distances[(size_t)offset + 1] = d3 - 1;
    701     offset += 2;
    702     d2 = d3;
    703   }
    704   
    705   if (offset != 0)
    706   {
    707     UPDATE_maxLen
    708     distances[(size_t)offset - 2] = (UInt32)maxLen;
    709     if (maxLen == lenLimit)
    710     {
    711       SkipMatchesSpec((UInt32)lenLimit, curMatch, MF_PARAMS(p));
    712       MOVE_POS_RET;
    713     }
    714   }
    715   
    716   if (maxLen < 3)
    717     maxLen = 3;
    718   
    719   GET_MATCHES_FOOTER(offset, maxLen)
    720 }
    721 
    722 /*
    723 static UInt32 Bt5_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    724 {
    725   UInt32 h2, h3, h4, d2, d3, d4, maxLen, offset, pos;
    726   UInt32 *hash;
    727   GET_MATCHES_HEADER(5)
    728 
    729   HASH5_CALC;
    730 
    731   hash = p->hash;
    732   pos = p->pos;
    733 
    734   d2 = pos - hash                  [h2];
    735   d3 = pos - (hash + kFix3HashSize)[h3];
    736   d4 = pos - (hash + kFix4HashSize)[h4];
    737 
    738   curMatch = (hash + kFix5HashSize)[hv];
    739 
    740   hash                  [h2] = pos;
    741   (hash + kFix3HashSize)[h3] = pos;
    742   (hash + kFix4HashSize)[h4] = pos;
    743   (hash + kFix5HashSize)[hv] = pos;
    744 
    745   maxLen = 0;
    746   offset = 0;
    747 
    748   if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
    749   {
    750     distances[0] = maxLen = 2;
    751     distances[1] = d2 - 1;
    752     offset = 2;
    753     if (*(cur - d2 + 2) == cur[2])
    754       distances[0] = maxLen = 3;
    755     else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    756     {
    757       distances[2] = maxLen = 3;
    758       distances[3] = d3 - 1;
    759       offset = 4;
    760       d2 = d3;
    761     }
    762   }
    763   else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    764   {
    765     distances[0] = maxLen = 3;
    766     distances[1] = d3 - 1;
    767     offset = 2;
    768     d2 = d3;
    769   }
    770   
    771   if (d2 != d4 && d4 < p->cyclicBufferSize
    772       && *(cur - d4) == *cur
    773       && *(cur - d4 + 3) == *(cur + 3))
    774   {
    775     maxLen = 4;
    776     distances[(size_t)offset + 1] = d4 - 1;
    777     offset += 2;
    778     d2 = d4;
    779   }
    780   
    781   if (offset != 0)
    782   {
    783     UPDATE_maxLen
    784     distances[(size_t)offset - 2] = maxLen;
    785     if (maxLen == lenLimit)
    786     {
    787       SkipMatchesSpec(lenLimit, curMatch, MF_PARAMS(p));
    788       MOVE_POS_RET;
    789     }
    790   }
    791 
    792   if (maxLen < 4)
    793     maxLen = 4;
    794   
    795   GET_MATCHES_FOOTER(offset, maxLen)
    796 }
    797 */
    798 
    799 static UInt32 Hc4_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    800 {
    801   UInt32 h2, h3, d2, d3, pos;
    802   unsigned maxLen, offset;
    803   UInt32 *hash;
    804   GET_MATCHES_HEADER(4)
    805 
    806   HASH4_CALC;
    807 
    808   hash = p->hash;
    809   pos = p->pos;
    810   
    811   d2 = pos - hash                  [h2];
    812   d3 = pos - (hash + kFix3HashSize)[h3];
    813   curMatch = (hash + kFix4HashSize)[hv];
    814 
    815   hash                  [h2] = pos;
    816   (hash + kFix3HashSize)[h3] = pos;
    817   (hash + kFix4HashSize)[hv] = pos;
    818 
    819   maxLen = 0;
    820   offset = 0;
    821 
    822   if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
    823   {
    824     maxLen = 2;
    825     distances[0] = 2;
    826     distances[1] = d2 - 1;
    827     offset = 2;
    828   }
    829   
    830   if (d2 != d3 && d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    831   {
    832     maxLen = 3;
    833     distances[(size_t)offset + 1] = d3 - 1;
    834     offset += 2;
    835     d2 = d3;
    836   }
    837   
    838   if (offset != 0)
    839   {
    840     UPDATE_maxLen
    841     distances[(size_t)offset - 2] = (UInt32)maxLen;
    842     if (maxLen == lenLimit)
    843     {
    844       p->son[p->cyclicBufferPos] = curMatch;
    845       MOVE_POS_RET;
    846     }
    847   }
    848   
    849   if (maxLen < 3)
    850     maxLen = 3;
    851 
    852   offset = (unsigned)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
    853       distances + offset, maxLen) - (distances));
    854   MOVE_POS_RET
    855 }
    856 
    857 /*
    858 static UInt32 Hc5_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    859 {
    860   UInt32 h2, h3, h4, d2, d3, d4, maxLen, offset, pos
    861   UInt32 *hash;
    862   GET_MATCHES_HEADER(5)
    863 
    864   HASH5_CALC;
    865 
    866   hash = p->hash;
    867   pos = p->pos;
    868   
    869   d2 = pos - hash                  [h2];
    870   d3 = pos - (hash + kFix3HashSize)[h3];
    871   d4 = pos - (hash + kFix4HashSize)[h4];
    872 
    873   curMatch = (hash + kFix5HashSize)[hv];
    874 
    875   hash                  [h2] = pos;
    876   (hash + kFix3HashSize)[h3] = pos;
    877   (hash + kFix4HashSize)[h4] = pos;
    878   (hash + kFix5HashSize)[hv] = pos;
    879 
    880   maxLen = 0;
    881   offset = 0;
    882 
    883   if (d2 < p->cyclicBufferSize && *(cur - d2) == *cur)
    884   {
    885     distances[0] = maxLen = 2;
    886     distances[1] = d2 - 1;
    887     offset = 2;
    888     if (*(cur - d2 + 2) == cur[2])
    889       distances[0] = maxLen = 3;
    890     else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    891     {
    892       distances[2] = maxLen = 3;
    893       distances[3] = d3 - 1;
    894       offset = 4;
    895       d2 = d3;
    896     }
    897   }
    898   else if (d3 < p->cyclicBufferSize && *(cur - d3) == *cur)
    899   {
    900     distances[0] = maxLen = 3;
    901     distances[1] = d3 - 1;
    902     offset = 2;
    903     d2 = d3;
    904   }
    905   
    906   if (d2 != d4 && d4 < p->cyclicBufferSize
    907       && *(cur - d4) == *cur
    908       && *(cur - d4 + 3) == *(cur + 3))
    909   {
    910     maxLen = 4;
    911     distances[(size_t)offset + 1] = d4 - 1;
    912     offset += 2;
    913     d2 = d4;
    914   }
    915   
    916   if (offset != 0)
    917   {
    918     UPDATE_maxLen
    919     distances[(size_t)offset - 2] = maxLen;
    920     if (maxLen == lenLimit)
    921     {
    922       p->son[p->cyclicBufferPos] = curMatch;
    923       MOVE_POS_RET;
    924     }
    925   }
    926   
    927   if (maxLen < 4)
    928     maxLen = 4;
    929 
    930   offset = (UInt32)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
    931       distances + offset, maxLen) - (distances));
    932   MOVE_POS_RET
    933 }
    934 */
    935 
    936 UInt32 Hc3Zip_MatchFinder_GetMatches(CMatchFinder *p, UInt32 *distances)
    937 {
    938   unsigned offset;
    939   GET_MATCHES_HEADER(3)
    940   HASH_ZIP_CALC;
    941   curMatch = p->hash[hv];
    942   p->hash[hv] = p->pos;
    943   offset = (unsigned)(Hc_GetMatchesSpec(lenLimit, curMatch, MF_PARAMS(p),
    944       distances, 2) - (distances));
    945   MOVE_POS_RET
    946 }
    947 
    948 static void Bt2_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
    949 {
    950   do
    951   {
    952     SKIP_HEADER(2)
    953     HASH2_CALC;
    954     curMatch = p->hash[hv];
    955     p->hash[hv] = p->pos;
    956     SKIP_FOOTER
    957   }
    958   while (--num != 0);
    959 }
    960 
    961 void Bt3Zip_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
    962 {
    963   do
    964   {
    965     SKIP_HEADER(3)
    966     HASH_ZIP_CALC;
    967     curMatch = p->hash[hv];
    968     p->hash[hv] = p->pos;
    969     SKIP_FOOTER
    970   }
    971   while (--num != 0);
    972 }
    973 
    974 static void Bt3_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
    975 {
    976   do
    977   {
    978     UInt32 h2;
    979     UInt32 *hash;
    980     SKIP_HEADER(3)
    981     HASH3_CALC;
    982     hash = p->hash;
    983     curMatch = (hash + kFix3HashSize)[hv];
    984     hash[h2] =
    985     (hash + kFix3HashSize)[hv] = p->pos;
    986     SKIP_FOOTER
    987   }
    988   while (--num != 0);
    989 }
    990 
    991 static void Bt4_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
    992 {
    993   do
    994   {
    995     UInt32 h2, h3;
    996     UInt32 *hash;
    997     SKIP_HEADER(4)
    998     HASH4_CALC;
    999     hash = p->hash;
   1000     curMatch = (hash + kFix4HashSize)[hv];
   1001     hash                  [h2] =
   1002     (hash + kFix3HashSize)[h3] =
   1003     (hash + kFix4HashSize)[hv] = p->pos;
   1004     SKIP_FOOTER
   1005   }
   1006   while (--num != 0);
   1007 }
   1008 
   1009 /*
   1010 static void Bt5_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
   1011 {
   1012   do
   1013   {
   1014     UInt32 h2, h3, h4;
   1015     UInt32 *hash;
   1016     SKIP_HEADER(5)
   1017     HASH5_CALC;
   1018     hash = p->hash;
   1019     curMatch = (hash + kFix5HashSize)[hv];
   1020     hash                  [h2] =
   1021     (hash + kFix3HashSize)[h3] =
   1022     (hash + kFix4HashSize)[h4] =
   1023     (hash + kFix5HashSize)[hv] = p->pos;
   1024     SKIP_FOOTER
   1025   }
   1026   while (--num != 0);
   1027 }
   1028 */
   1029 
   1030 static void Hc4_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
   1031 {
   1032   do
   1033   {
   1034     UInt32 h2, h3;
   1035     UInt32 *hash;
   1036     SKIP_HEADER(4)
   1037     HASH4_CALC;
   1038     hash = p->hash;
   1039     curMatch = (hash + kFix4HashSize)[hv];
   1040     hash                  [h2] =
   1041     (hash + kFix3HashSize)[h3] =
   1042     (hash + kFix4HashSize)[hv] = p->pos;
   1043     p->son[p->cyclicBufferPos] = curMatch;
   1044     MOVE_POS
   1045   }
   1046   while (--num != 0);
   1047 }
   1048 
   1049 /*
   1050 static void Hc5_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
   1051 {
   1052   do
   1053   {
   1054     UInt32 h2, h3, h4;
   1055     UInt32 *hash;
   1056     SKIP_HEADER(5)
   1057     HASH5_CALC;
   1058     hash = p->hash;
   1059     curMatch = hash + kFix5HashSize)[hv];
   1060     hash                  [h2] =
   1061     (hash + kFix3HashSize)[h3] =
   1062     (hash + kFix4HashSize)[h4] =
   1063     (hash + kFix5HashSize)[hv] = p->pos;
   1064     p->son[p->cyclicBufferPos] = curMatch;
   1065     MOVE_POS
   1066   }
   1067   while (--num != 0);
   1068 }
   1069 */
   1070 
   1071 void Hc3Zip_MatchFinder_Skip(CMatchFinder *p, UInt32 num)
   1072 {
   1073   do
   1074   {
   1075     SKIP_HEADER(3)
   1076     HASH_ZIP_CALC;
   1077     curMatch = p->hash[hv];
   1078     p->hash[hv] = p->pos;
   1079     p->son[p->cyclicBufferPos] = curMatch;
   1080     MOVE_POS
   1081   }
   1082   while (--num != 0);
   1083 }
   1084 
   1085 void MatchFinder_CreateVTable(CMatchFinder *p, IMatchFinder *vTable)
   1086 {
   1087   vTable->Init = (Mf_Init_Func)MatchFinder_Init;
   1088   vTable->GetNumAvailableBytes = (Mf_GetNumAvailableBytes_Func)MatchFinder_GetNumAvailableBytes;
   1089   vTable->GetPointerToCurrentPos = (Mf_GetPointerToCurrentPos_Func)MatchFinder_GetPointerToCurrentPos;
   1090   if (!p->btMode)
   1091   {
   1092     /* if (p->numHashBytes <= 4) */
   1093     {
   1094       vTable->GetMatches = (Mf_GetMatches_Func)Hc4_MatchFinder_GetMatches;
   1095       vTable->Skip = (Mf_Skip_Func)Hc4_MatchFinder_Skip;
   1096     }
   1097     /*
   1098     else
   1099     {
   1100       vTable->GetMatches = (Mf_GetMatches_Func)Hc5_MatchFinder_GetMatches;
   1101       vTable->Skip = (Mf_Skip_Func)Hc5_MatchFinder_Skip;
   1102     }
   1103     */
   1104   }
   1105   else if (p->numHashBytes == 2)
   1106   {
   1107     vTable->GetMatches = (Mf_GetMatches_Func)Bt2_MatchFinder_GetMatches;
   1108     vTable->Skip = (Mf_Skip_Func)Bt2_MatchFinder_Skip;
   1109   }
   1110   else if (p->numHashBytes == 3)
   1111   {
   1112     vTable->GetMatches = (Mf_GetMatches_Func)Bt3_MatchFinder_GetMatches;
   1113     vTable->Skip = (Mf_Skip_Func)Bt3_MatchFinder_Skip;
   1114   }
   1115   else /* if (p->numHashBytes == 4) */
   1116   {
   1117     vTable->GetMatches = (Mf_GetMatches_Func)Bt4_MatchFinder_GetMatches;
   1118     vTable->Skip = (Mf_Skip_Func)Bt4_MatchFinder_Skip;
   1119   }
   1120   /*
   1121   else
   1122   {
   1123     vTable->GetMatches = (Mf_GetMatches_Func)Bt5_MatchFinder_GetMatches;
   1124     vTable->Skip = (Mf_Skip_Func)Bt5_MatchFinder_Skip;
   1125   }
   1126   */
   1127 }
	duckstation duckstation, but archived from the revision just before upstream changed it to a proprietary software project, this version is the libre one
	git clone https://git.neptards.moe/u3shit/duckstation.git
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