public static int SaveDictHC(CCtxT *streamHCPtr, byte *safeBuffer, int dictSize)
{
CCtxT *streamPtr = streamHCPtr;
int prefixSize = (int)(streamPtr->End - (streamPtr->BaseP + streamPtr->DictLimit));
if (dictSize > 64 * KB)
{
dictSize = 64 * KB;
}
if (dictSize < 4)
{
dictSize = 0;
}
if (dictSize > prefixSize)
{
dictSize = prefixSize;
}
LZ4MemoryHelper.Move(safeBuffer, streamPtr->End - dictSize, dictSize);
uint endIndex = (uint)(streamPtr->End - streamPtr->BaseP);
streamPtr->End = safeBuffer + dictSize;
streamPtr->BaseP = streamPtr->End - endIndex;
streamPtr->DictLimit = endIndex - (uint)dictSize;
streamPtr->LowLimit = endIndex - (uint)dictSize;
if (streamPtr->NextToUpdate < streamPtr->DictLimit)
{
streamPtr->NextToUpdate = streamPtr->DictLimit;
}
return(dictSize);
}
private static int CompressHCContinueDestSize(CCtxT *ctxPtr, byte *src, byte *dst, int *srcSizePtr, int targetDestSize)
{
return(CompressHCContinueGeneric(
ctxPtr,
src,
dst,
srcSizePtr,
targetDestSize,
LimitedOutputDirective.LimitedDestSize));
}
private static int CompressHCContinueGeneric(CCtxT *ctxPtr, byte *src, byte *dst, int *srcSizePtr, int dstCapacity, LimitedOutputDirective limit)
{
// auto-init if forgotten
if (ctxPtr->BaseP == null)
{
InitializeHC(ctxPtr, src);
}
// Check overflow
if ((size_t)(ctxPtr->End - ctxPtr->BaseP) > 2 * GB)
{
size_t dictSize = (size_t)(ctxPtr->End - ctxPtr->BaseP) - ctxPtr->DictLimit;
if (dictSize > 64 * KB)
{
dictSize = 64 * KB;
}
LoadDictHC(ctxPtr, ctxPtr->End - dictSize, (int)dictSize);
}
// Check if blocks follow each other
if (src != ctxPtr->End)
{
SetExternalDict(ctxPtr, src);
}
// Check overlapping input/dictionary space
{
byte *sourceEnd = src + *srcSizePtr;
byte *dictBegin = ctxPtr->DictBase + ctxPtr->LowLimit;
byte *dictEnd = ctxPtr->DictBase + ctxPtr->DictLimit;
if (sourceEnd > dictBegin && src < dictEnd)
{
if (sourceEnd > dictEnd)
{
sourceEnd = dictEnd;
}
ctxPtr->LowLimit = (uint)(sourceEnd - ctxPtr->DictBase);
if (ctxPtr->DictLimit - ctxPtr->LowLimit < 4)
{
ctxPtr->LowLimit = ctxPtr->DictLimit;
}
}
}
return(CompressGeneric(
ctxPtr,
src,
dst,
srcSizePtr,
dstCapacity,
ctxPtr->CompressionLevel,
limit));
}
public static void InitializeHC(CCtxT *hc4, byte *start)
{
LZ4MemoryHelper.Zero((byte *)hc4->HashTable, HashTableSizeHC * sizeof(uint));
LZ4MemoryHelper.Fill((byte *)hc4->ChainTable, 0xFF, MaxD * sizeof(ushort));
hc4->NextToUpdate = 64 * KB;
hc4->BaseP = start - 64 * KB;
hc4->End = start;
hc4->DictBase = start - 64 * KB;
hc4->DictLimit = 64 * KB;
hc4->LowLimit = 64 * KB;
}
public static int CompressHCContinue(CCtxT *ctxPtr, byte *src, byte *dst, int srcSize, int dstCapacity)
{
return(CompressHCContinueGeneric(
ctxPtr,
src,
dst,
&srcSize,
dstCapacity,
dstCapacity < CompressBound(srcSize)
? LimitedOutputDirective.LimitedOutput
: LimitedOutputDirective.NoLimit));
}
private static int CompressHCDestSize(CCtxT *ctx, byte *source, byte *dest, int *sourceSizePtr, int targetDestSize, int cLevel)
{
InitializeHC(ctx, source);
return(CompressGeneric(
ctx,
source,
dest,
sourceSizePtr,
targetDestSize,
cLevel,
LimitedOutputDirective.LimitedDestSize));
}
internal static int CompressHC(byte *src, byte *dst, int srcSize, int dstCapacity, int compressionLevel)
{
CCtxT *ptr = AllocCtx();
try
{
return(CompressHCExtStateHC(ptr, src, dst, srcSize, dstCapacity, compressionLevel));
}
finally
{
FreeCtx(ptr);
}
}
private static void SetExternalDict(CCtxT *ctxPtr, byte *newBlock)
{
if (ctxPtr->End >= ctxPtr->BaseP + 4)
{
Insert(ctxPtr, ctxPtr->End - 3); // Referencing remaining dictionary content
}
// Only one memory segment for extDict, so any previous extDict is lost at this stage
ctxPtr->LowLimit = ctxPtr->DictLimit;
ctxPtr->DictLimit = (uint)(ctxPtr->End - ctxPtr->BaseP);
ctxPtr->DictBase = ctxPtr->BaseP;
ctxPtr->BaseP = newBlock - ctxPtr->DictLimit;
ctxPtr->End = newBlock;
ctxPtr->NextToUpdate = ctxPtr->DictLimit; // match referencing will resume from there
}
public static void SetCompressionLevel(CCtxT *ctxPtr, int compressionLevel)
{
if (compressionLevel < 1)
{
compressionLevel = 1;
}
if (compressionLevel > CLevelMax)
{
compressionLevel = CLevelMax;
}
ctxPtr->CompressionLevel = compressionLevel;
}
private static int InsertAndFindBestMatch(CCtxT *hc4, byte *ip, byte *iLimit, byte **matchpos, int maxNbAttempts, int patternAnalysis)
{
byte *uselessPtr = ip;
return(InsertAndGetWiderMatch(
hc4,
ip,
ip,
iLimit,
MinMatch - 1,
matchpos,
&uselessPtr,
maxNbAttempts,
patternAnalysis));
}
private static MatchT FindLongerMatch(CCtxT *ctx, byte *ip, byte *iHighLimit, int minLen, int nbSearches)
{
MatchT match;
LZ4MemoryHelper.Zero((byte *)&match, sizeof(MatchT));
byte *matchPtr = null;
int matchLength = InsertAndGetWiderMatch(ctx, ip, ip, iHighLimit, minLen, &matchPtr, &ip, nbSearches, 1);
if (matchLength <= minLen)
{
return(match);
}
match.Len = matchLength;
match.Off = (int)(ip - matchPtr);
return(match);
}
private static int LoadDictHC(CCtxT *ctxPtr, byte *dictionary, int dictSize)
{
if (dictSize > 64 * KB)
{
dictionary += dictSize - 64 * KB;
dictSize = 64 * KB;
}
InitializeHC(ctxPtr, dictionary);
ctxPtr->End = dictionary + dictSize;
if (dictSize >= 4)
{
Insert(ctxPtr, ctxPtr->End - 3);
}
return(dictSize);
}
private static int CompressGeneric(CCtxT *ctx, byte *src, byte *dst, int *srcSizePtr, int dstCapacity, int cLevel, LimitedOutputDirective limit)
{
if ((limit == LimitedOutputDirective.LimitedDestSize) && (dstCapacity < 1))
{
return(0); // Impossible to store anything
}
if (*srcSizePtr > MaxInputSize)
{
return(0); // Unsupported input size (too large or negative)
}
ctx->End += *srcSizePtr;
if (cLevel < 1)
{
cLevel = CLevelDefault; // note : convention is different from lz4frame, maybe something to review
}
cLevel = Math.Min(CLevelMax, cLevel);
CParams cParam = ClTable[cLevel];
if (cParam.Strat == StratE.HC)
{
return(CompressHashChain(
ctx,
src,
dst,
srcSizePtr,
dstCapacity,
cParam.NbSearches,
limit));
}
return(CompressOptimal(
ctx,
src,
dst,
srcSizePtr,
dstCapacity,
(int)cParam.NbSearches,
cParam.TargetLength,
limit,
cLevel == CLevelMax ? 1 : 0)); // ultra mode
}
private static int CompressHCExtStateHC(CCtxT *ctx, byte *src, byte *dst, int srcSize, int dstCapacity, int compressionLevel)
{
if (((size_t)ctx & (size_t)(sizeof(void *) - 1)) != 0)
{
return(0);
}
InitializeHC(ctx, src);
return(CompressGeneric(
ctx,
src,
dst,
&srcSize,
dstCapacity,
compressionLevel,
dstCapacity < CompressBound(srcSize)
? LimitedOutputDirective.LimitedOutput
: LimitedOutputDirective.NoLimit));
}
private static void Insert(CCtxT *hc4, byte *ip)
{
ushort *chainTable = hc4->ChainTable;
uint * hashTable = hc4->HashTable;
byte * basep = hc4->BaseP;
uint target = (uint)(ip - basep);
uint idx = hc4->NextToUpdate;
while (idx < target)
{
uint h = HashPtr(basep + idx);
uint delta = idx - hashTable[h];
if (delta > MaxDistance)
{
delta = MaxDistance;
}
DeltaNextU16(chainTable, (ushort)idx, (ushort)delta);
hashTable[h] = idx;
idx++;
}
hc4->NextToUpdate = target;
}
private static int CompressHashChain(CCtxT *ctx, byte *source, byte *dest, int *srcSizePtr, int maxOutputSize, uint maxNbAttempts, LimitedOutputDirective limit)
{
int inputSize = *srcSizePtr;
int patternAnalysis = maxNbAttempts > 64 ? 1 : 0; // levels 8+
byte *ip = source;
byte *anchor = ip;
byte *iend = ip + inputSize;
byte *mflimit = iend - MFLimit;
byte *matchlimit = (iend - LastLiterals);
byte *optr;
byte *op = dest;
byte *oend = op + maxOutputSize;
byte *refPos = null;
byte *start2 = null;
byte *ref2 = null;
byte *start3 = null;
byte *ref3 = null;
// init
*srcSizePtr = 0;
if (limit == LimitedOutputDirective.LimitedDestSize)
{
oend -= LastLiterals; // Hack for support LZ4 format restriction
}
if (inputSize < LZ4MinLength)
{
goto _last_literals; // Input too small, no compression (all literals)
}
// Main Loop
while (ip < mflimit)
{
int ml = InsertAndFindBestMatch(
ctx,
ip,
matchlimit,
&refPos,
(int)maxNbAttempts,
patternAnalysis);
if (ml < MinMatch)
{
ip++;
continue;
}
// saved, in case we would skip too much
byte *start0 = ip;
byte *ref0 = refPos;
int ml0 = ml;
_Search2:
int ml2;
if (ip + ml < mflimit)
{
ml2 = InsertAndGetWiderMatch(
ctx,
ip + ml - 2,
ip + 0,
matchlimit,
ml,
&ref2,
&start2,
(int)maxNbAttempts,
patternAnalysis);
}
else
{
ml2 = ml;
}
if (ml2 == ml)
{
// No better match
optr = op;
if (EncodeSequence(&ip, &op, &anchor, ml, refPos, limit, oend) != 0)
{
goto _dest_overflow;
}
continue;
}
if (start0 < ip)
{
if (start2 < ip + ml0)
{
// empirical
ip = start0;
refPos = ref0;
ml = ml0;
}
}
// Here, start0==ip
if (start2 - ip < 3)
{
// First Match too small : removed
ml = ml2;
ip = start2;
refPos = ref2;
goto _Search2;
}
_Search3:
// At this stage, we have :
// ml2 > ml1, and
// ip1+3 <= ip2 (usually < ip1+ml1)
if ((start2 - ip) < OptimalML)
{
int newMl = ml;
if (newMl > OptimalML)
{
newMl = OptimalML;
}
if (ip + newMl > start2 + ml2 - MinMatch)
{
newMl = (int)(start2 - ip) + ml2 - MinMatch;
}
int correction = newMl - (int)(start2 - ip);
if (correction > 0)
{
start2 += correction;
ref2 += correction;
ml2 -= correction;
}
}
// Now, we have start2 = ip+new_ml, with new_ml = min(ml, OPTIMAL_ML=18)
int ml3;
if (start2 + ml2 < mflimit)
{
ml3 = InsertAndGetWiderMatch(
ctx,
start2 + ml2 - 3,
start2,
matchlimit,
ml2,
&ref3,
&start3,
(int)maxNbAttempts,
patternAnalysis);
}
else
{
ml3 = ml2;
}
if (ml3 == ml2)
{
// No better match : 2 sequences to encode
// ip & ref are known; Now for ml
if (start2 < ip + ml)
{
ml = (int)(start2 - ip);
}
// Now, encode 2 sequences
optr = op;
if (EncodeSequence(&ip, &op, &anchor, ml, refPos, limit, oend) != 0)
{
goto _dest_overflow;
}
ip = start2;
optr = op;
if (EncodeSequence(&ip, &op, &anchor, ml2, ref2, limit, oend) != 0)
{
goto _dest_overflow;
}
continue;
}
if (start3 < ip + ml + 3)
{
// Not enough space for match 2 : remove it
if (start3 >= (ip + ml))
{
// can write Seq1 immediately ==> Seq2 is removed, so Seq3 becomes Seq1
if (start2 < ip + ml)
{
int correction = (int)(ip + ml - start2);
start2 += correction;
ref2 += correction;
ml2 -= correction;
if (ml2 < MinMatch)
{
start2 = start3;
ref2 = ref3;
ml2 = ml3;
}
}
optr = op;
if (EncodeSequence(&ip, &op, &anchor, ml, refPos, limit, oend) != 0)
{
goto _dest_overflow;
}
ip = start3;
refPos = ref3;
ml = ml3;
start0 = start2;
ref0 = ref2;
ml0 = ml2;
goto _Search2;
}
start2 = start3;
ref2 = ref3;
ml2 = ml3;
goto _Search3;
}
// OK, now we have 3 ascending matches; let's write at least the first one
// ip & ref are known; Now for ml
if (start2 < ip + ml)
{
if (start2 - ip < (int)MLMask)
{
if (ml > OptimalML)
{
ml = OptimalML;
}
if (ip + ml > start2 + ml2 - MinMatch)
{
ml = (int)(start2 - ip) + ml2 - MinMatch;
}
int correction = ml - (int)(start2 - ip);
if (correction > 0)
{
start2 += correction;
ref2 += correction;
ml2 -= correction;
}
}
else
{
ml = (int)(start2 - ip);
}
}
optr = op;
if (EncodeSequence(&ip, &op, &anchor, ml, refPos, limit, oend) != 0)
{
goto _dest_overflow;
}
ip = start2;
refPos = ref2;
ml = ml2;
start2 = start3;
ref2 = ref3;
ml2 = ml3;
goto _Search3;
}
_last_literals: // Encode last literals
{
size_t lastRunSize = (size_t)(iend - anchor); // literals
size_t litLength = (lastRunSize + 255 - RunMask) / 255;
size_t totalSize = 1 + litLength + lastRunSize;
if (limit == LimitedOutputDirective.LimitedDestSize)
{
oend += LastLiterals; // restore correct value
}
if ((limit != 0) && (op + totalSize > oend))
{
if (limit == LimitedOutputDirective.LimitedOutput)
{
return(0); // Check output limit
}
// adapt lastRunSize to fill 'dest'
lastRunSize = (size_t)(oend - op) - 1;
litLength = (lastRunSize + 255 - RunMask) / 255;
lastRunSize -= litLength;
}
ip = anchor + lastRunSize;
if (lastRunSize >= RunMask)
{
size_t accumulator = lastRunSize - RunMask;
*op++ = (byte)(RunMask << MLBits);
for (; accumulator >= 255; accumulator -= 255)
{
*op++ = 255;
}
*op++ = (byte)accumulator;
}
else
{
*op++ = (byte)(lastRunSize << MLBits);
}
LZ4MemoryHelper.Copy(op, anchor, (int)lastRunSize);
op += lastRunSize;
}
// End
*srcSizePtr = (int)(ip - source);
return((int)(op - dest));
_dest_overflow:
if (limit != LimitedOutputDirective.LimitedDestSize)
{
return(0);
}
op = optr; // restore correct out pointer
goto _last_literals;
}
// -----------------------------------------------------------------
private static int CompressOptimal(CCtxT *ctx, byte *source, byte *dst, int *srcSizePtr, int dstCapacity,
int nbSearches, size_t sufficientLen, LimitedOutputDirective limit, int fullUpdate)
{
const int TrailingLiterals = 3;
OptimalT *opt = stackalloc OptimalT[OptNum + TrailingLiterals];
byte *ip = source;
byte *anchor = ip;
byte *iend = ip + *srcSizePtr;
byte *mflimit = iend - MFLimit;
byte *matchlimit = iend - LastLiterals;
byte *op = dst;
byte *opSaved;
byte *oend = op + dstCapacity;
*srcSizePtr = 0;
if (limit == LimitedOutputDirective.LimitedDestSize)
{
oend -= LastLiterals;
}
if (sufficientLen >= OptNum)
{
sufficientLen = OptNum - 1;
}
// Main Loop
while (ip < mflimit)
{
int llen = (int)(ip - anchor);
int bestMlen, bestOff;
int cur, lastMatchPos;
MatchT firstMatch = FindLongerMatch(ctx, ip, matchlimit, MinMatch - 1, nbSearches);
if (firstMatch.Len == 0)
{
ip++;
continue;
}
if ((size_t)firstMatch.Len > sufficientLen)
{
int firstML = firstMatch.Len;
byte *matchPos = ip - firstMatch.Off;
opSaved = op;
if (EncodeSequence(&ip, &op, &anchor, firstML, matchPos, limit, oend) != 0)
{
goto _dest_overflow;
}
continue;
}
// set prices for first positions (literals)
{
int rPos;
for (rPos = 0; rPos < MinMatch; rPos++)
{
int cost = LiteralsPrice(llen + rPos);
opt[rPos].Mlen = 1;
opt[rPos].Off = 0;
opt[rPos].Litlen = llen + rPos;
opt[rPos].Price = cost;
}
}
// set prices using initial match
{
int mlen = MinMatch;
int matchML = firstMatch.Len; // necessarily < sufficient_len < LZ4_OPT_NUM
int offset = firstMatch.Off;
for (; mlen <= matchML; mlen++)
{
int cost = SequencePrice(llen, mlen);
opt[mlen].Mlen = mlen;
opt[mlen].Off = offset;
opt[mlen].Litlen = llen;
opt[mlen].Price = cost;
}
}
lastMatchPos = firstMatch.Len;
{
int addLit;
for (addLit = 1; addLit <= TrailingLiterals; addLit++)
{
opt[lastMatchPos + addLit].Mlen = 1;
opt[lastMatchPos + addLit].Off = 0;
opt[lastMatchPos + addLit].Litlen = addLit;
opt[lastMatchPos + addLit].Price = opt[lastMatchPos].Price + LiteralsPrice(addLit);
}
}
// check further positions
for (cur = 1; cur < lastMatchPos; cur++)
{
byte *curPtr = ip + cur;
if (curPtr >= mflimit)
{
break;
}
if (fullUpdate != 0)
{
if ((opt[cur + 1].Price <= opt[cur].Price) &&
(opt[cur + MinMatch].Price < opt[cur].Price + 3))
{
continue;
}
}
else
{
if (opt[cur + 1].Price <= opt[cur].Price)
{
continue;
}
}
MatchT newMatch = FindLongerMatch(
ctx,
curPtr,
matchlimit,
fullUpdate != 0 ? MinMatch - 1 : lastMatchPos - cur,
nbSearches);
if (newMatch.Len == 0)
{
continue;
}
if ((size_t)newMatch.Len > sufficientLen || newMatch.Len + cur >= OptNum)
{
// immediate encoding
bestMlen = newMatch.Len;
bestOff = newMatch.Off;
lastMatchPos = cur + 1;
goto encode;
}
// before match : set price with literals at beginning
{
int baseLitlen = opt[cur].Litlen;
for (int litlen = 1; litlen < MinMatch; litlen++)
{
int price = opt[cur].Price - LiteralsPrice(baseLitlen) + LiteralsPrice(baseLitlen + litlen);
int pos = cur + litlen;
if (price >= opt[pos].Price)
{
continue;
}
opt[pos].Mlen = 1;
opt[pos].Off = 0;
opt[pos].Litlen = baseLitlen + litlen;
opt[pos].Price = price;
}
}
// set prices using match at position = cur
{
int matchML = newMatch.Len;
int ml = MinMatch;
for (; ml <= matchML; ml++)
{
int pos = cur + ml;
int offset = newMatch.Off;
int price;
int ll;
if (opt[cur].Mlen == 1)
{
ll = opt[cur].Litlen;
price = ((cur > ll) ? opt[cur - ll].Price : 0) + SequencePrice(ll, ml);
}
else
{
ll = 0;
price = opt[cur].Price + SequencePrice(0, ml);
}
if ((pos > lastMatchPos + TrailingLiterals) || (price <= opt[pos].Price))
{
if (ml == matchML && lastMatchPos < pos)
{
lastMatchPos = pos;
}
opt[pos].Mlen = ml;
opt[pos].Off = offset;
opt[pos].Litlen = ll;
opt[pos].Price = price;
}
}
}
{
int addLit;
for (addLit = 1; addLit <= TrailingLiterals; addLit++)
{
opt[lastMatchPos + addLit].Mlen = 1;
opt[lastMatchPos + addLit].Off = 0;
opt[lastMatchPos + addLit].Litlen = addLit;
opt[lastMatchPos + addLit].Price = opt[lastMatchPos].Price + LiteralsPrice(addLit);
}
}
}
bestMlen = opt[lastMatchPos].Mlen;
bestOff = opt[lastMatchPos].Off;
cur = lastMatchPos - bestMlen;
encode: // cur, last_match_pos, best_mlen, best_off must be set
{
int candidate_pos = cur;
int selected_matchLength = bestMlen;
int selected_offset = bestOff;
while (true)
{
int next_matchLength = opt[candidate_pos].Mlen;
int next_offset = opt[candidate_pos].Off;
opt[candidate_pos].Mlen = selected_matchLength;
opt[candidate_pos].Off = selected_offset;
selected_matchLength = next_matchLength;
selected_offset = next_offset;
if (next_matchLength > candidate_pos)
{
break;
}
candidate_pos -= next_matchLength;
}
}
{
int rPos = 0;
while (rPos < lastMatchPos)
{
int ml = opt[rPos].Mlen;
int offset = opt[rPos].Off;
if (ml == 1)
{
ip++;
rPos++;
continue;
}
rPos += ml;
opSaved = op;
if (EncodeSequence(&ip, &op, &anchor, ml, ip - offset, limit, oend) != 0)
{
goto _dest_overflow;
}
}
}
}
_last_literals:
{
size_t lastRunSize = (size_t)(iend - anchor);
size_t litLength = (lastRunSize + 255 - RunMask) / 255;
size_t totalSize = 1 + litLength + lastRunSize;
if (limit == LimitedOutputDirective.LimitedDestSize)
{
oend += LastLiterals;
}
if (limit != 0 && op + totalSize > oend)
{
if (limit == LimitedOutputDirective.LimitedOutput)
{
return(0);
}
lastRunSize = (size_t)(oend - op) - 1;
litLength = (lastRunSize + 255 - RunMask) / 255;
lastRunSize -= litLength;
}
ip = anchor + lastRunSize;
if (lastRunSize >= RunMask)
{
size_t accumulator = lastRunSize - RunMask;
* op++ = (byte)(RunMask << MLBits);
for (; accumulator >= 255; accumulator -= 255)
{
*op++ = 255;
}
*op++ = (byte)accumulator;
}
else
{
*op++ = (byte)(lastRunSize << MLBits);
}
LZ4MemoryHelper.Copy(op, anchor, (int)lastRunSize);
op += lastRunSize;
}
// End
*srcSizePtr = (int)(ip - source);
return((int)(op - dst));
_dest_overflow:
if (limit != LimitedOutputDirective.LimitedDestSize)
{
return(0);
}
op = opSaved; // restore correct out pointer
goto _last_literals;
}
private static void FreeCtx(CCtxT *context)
{
LZ4MemoryHelper.Free(context);
}
// initialization
public static void ResetStreamHC(CCtxT *ctxPtr, int compressionLevel)
{
ctxPtr->BaseP = null;
SetCompressionLevel(ctxPtr, compressionLevel);
}
private static int InsertAndGetWiderMatch(CCtxT *hc4, byte *ip, byte *iLowLimit, byte *iHighLimit, int longest,
byte **matchpos, byte **startpos, int maxNbAttempts, int patternAnalysis)
{
ushort *chainTable = hc4->ChainTable;
uint * hashTable = hc4->HashTable;
byte * basep = hc4->BaseP;
uint dictLimit = hc4->DictLimit;
byte * lowPrefixPtr = basep + dictLimit;
uint lowLimit = hc4->LowLimit + 64 * KB > (uint)(ip - basep)
? hc4->LowLimit
: (uint)(ip - basep) - MaxDistance;
byte * dictBase = hc4->DictBase;
int delta = (int)(ip - iLowLimit);
int nbAttempts = maxNbAttempts;
uint pattern = LZ4MemoryHelper.Peek32(ip);
RepeatStateE repeat = RepeatStateE.RepUntested;
int srcPatternLength = 0;
// First Match
Insert(hc4, ip);
uint matchIndex = hashTable[HashPtr(ip)];
while ((matchIndex >= lowLimit) && (nbAttempts != 0))
{
nbAttempts--;
if (matchIndex >= dictLimit)
{
byte *matchPtr = basep + matchIndex;
if (*(iLowLimit + longest) == *(matchPtr - delta + longest))
{
if (LZ4MemoryHelper.Peek32(matchPtr) == pattern)
{
int mlt = MinMatch + (int)Count(ip + MinMatch, matchPtr + MinMatch, iHighLimit);
int back = 0;
while ((ip + back > iLowLimit) &&
(matchPtr + back > lowPrefixPtr) &&
(ip[back - 1] == matchPtr[back - 1]))
{
back--;
}
mlt -= back;
if (mlt > longest)
{
longest = mlt;
*matchpos = matchPtr + back;
*startpos = ip + back;
}
}
}
}
else
{
byte *matchPtr = dictBase + matchIndex;
if (LZ4MemoryHelper.Peek32(matchPtr) == pattern)
{
int back = 0;
byte *vLimit = ip + (dictLimit - matchIndex);
if (vLimit > iHighLimit)
{
vLimit = iHighLimit;
}
int mlt = MinMatch + (int)Count(ip + MinMatch, matchPtr + MinMatch, vLimit);
if ((ip + mlt == vLimit) && (vLimit < iHighLimit))
{
mlt += (int)Count(ip + mlt, basep + dictLimit, iHighLimit);
}
while ((ip + back > iLowLimit) &&
(matchIndex + back > lowLimit) &&
(ip[back - 1] == matchPtr[back - 1]))
{
back--;
}
mlt -= back;
if (mlt > longest)
{
longest = mlt;
*matchpos = basep + matchIndex + back;
*startpos = ip + back;
}
}
}
{
ushort nextOffset = DeltaNextU16(chainTable, (ushort)matchIndex);
matchIndex -= nextOffset;
if ((patternAnalysis != 0) && (nextOffset == 1))
{
// may be a repeated pattern
if (repeat == RepeatStateE.RepUntested)
{
if (((pattern & 0xFFFF) == pattern >> 16) &
((pattern & 0xFF) == pattern >> 24))
{
repeat = RepeatStateE.RepConfirmed;
srcPatternLength = (int)CountPattern(ip + 4, iHighLimit, pattern) + 4;
}
else
{
repeat = RepeatStateE.RepNot;
}
}
if ((repeat == RepeatStateE.RepConfirmed) && (matchIndex >= dictLimit))
{
byte *matchPtr = basep + matchIndex;
if (LZ4MemoryHelper.Peek32(matchPtr) == pattern)
{
int forwardPatternLength = (int)CountPattern(matchPtr + sizeof(uint), iHighLimit, pattern) + sizeof(uint);
byte *maxLowPtr = lowPrefixPtr + MaxDistance >= ip
? lowPrefixPtr
: ip - MaxDistance;
int backLength = (int)ReverseCountPattern(matchPtr, maxLowPtr, pattern);
int currentSegmentLength = backLength + forwardPatternLength;
if ((currentSegmentLength >= srcPatternLength) &&
(forwardPatternLength <= srcPatternLength))
{
matchIndex += (uint)(forwardPatternLength - srcPatternLength);
}
else
{
matchIndex -= (uint)backLength;
}
}
}
}
}
}
return(longest);
}
