public int Decompress(
byte *compressedBuffer,
byte *decompressedBuffer,
int compressedSize,
int maxDecompressedSize)
{
fixed(sbyte *dec = m_DecArray)
fixed(sbyte *dec2Ptr = m_Dec2table)
{
// Local Variables
byte *ip = (byte *)compressedBuffer;
byte *iend = ip + compressedSize;
byte *r;
byte *op = (byte *)decompressedBuffer;
byte *oend = op + maxDecompressedSize;
byte *cpy;
byte token;
int length;
// Main Loop
while (ip < iend)
{
// get runLength
token = *ip++;
if ((length = (token >> LZ4Util.ML_BITS)) == LZ4Util.RUN_MASK)
{
int s = 255; while ((ip < iend) && (s == 255))
{
s = *ip++; length += s;
}
}
// copy literals
cpy = op + length;
if ((cpy > oend - LZ4Util.COPYLENGTH) || (ip + length > iend - LZ4Util.COPYLENGTH))
{
if (cpy > oend)
{
goto _output_error; // Error : request to write beyond destination buffer
}
if (ip + length > iend)
{
goto _output_error; // Error : request to read beyond source buffer
}
LZ4Util.CopyMemory(op, ip, length);
op += length;
ip += length;
if (ip < iend)
{
goto _output_error; // Error : LZ4 format violation
}
break; //Necessarily EOF
}
do
{
*(ulong *)op = *(ulong *)ip; op += 8; ip += 8;
} while (op < cpy);; ip -= (op - cpy); op = cpy;
// get offset
{ r = (cpy) - *(ushort *)ip; }; ip += 2;
if (r < decompressedBuffer)
{
goto _output_error;
}
// get matchlength
if ((length = (int)(token & LZ4Util.ML_MASK)) == LZ4Util.ML_MASK)
{
while (ip < iend)
{
int s = *ip++; length += s; if (s == 255)
{
continue;
}
break;
}
}
// copy repeated sequence
if (op - r < STEPSIZE)
{
var dec2 = dec2Ptr[op - r];
*op++ = *r++;
*op++ = *r++;
*op++ = *r++;
*op++ = *r++;
r -= dec[op - r];
*(uint *)op = *(uint *)r; op += STEPSIZE - 4;
r -= dec2;
}
else
{
*(ulong *)op = *(ulong *)r; op += 8; r += 8;;
}
cpy = op + length - (STEPSIZE - 4);
if (cpy > oend - LZ4Util.COPYLENGTH)
{
if (cpy > oend)
{
goto _output_error;
}
if (op < (oend - LZ4Util.COPYLENGTH))
{
do
{
*(ulong *)op = *(ulong *)r; op += 8; r += 8;
} while (op < (oend - LZ4Util.COPYLENGTH));
}
;
while (op < cpy)
{
*op++ = *r++;
}
op = cpy;
if (op == oend)
{
goto _output_error; // Check EOF (should never happen, since last 5 bytes are supposed to be literals)
}
continue;
}
if (op < cpy)
{
do
{
*(ulong *)op = *(ulong *)r; op += 8; r += 8;
} while (op < cpy);
}
;
op = cpy; // correction
}
return((int)(((byte *)op) - decompressedBuffer));
_output_error:
return((int)(-(((byte *)ip) - compressedBuffer)));
}
}
public int DecompressKnownSize(byte *compressed, byte *decompressedBuffer, int decompressedSize)
{
fixed(sbyte *dec = m_DecArray)
fixed(sbyte *dec2Ptr = m_Dec2table)
{
// Local Variables
byte *ip = (byte *)compressed;
byte *r;
byte *op = (byte *)decompressedBuffer;
byte *oend = op + decompressedSize;
byte *cpy;
byte token;
int len, length;
// Main Loop
while (true)
{
// get runLength
token = *ip++;
if ((length = (token >> LZ4Util.ML_BITS)) == LZ4Util.RUN_MASK)
{
for (; (len = *ip++) == 255; length += 255)
{
}
length += len;
}
cpy = op + length;
if (cpy > oend - LZ4Util.COPYLENGTH)
{
if (cpy > oend)
{
goto _output_error;
}
LZ4Util.CopyMemory(op, ip, length);
ip += length;
break;
}
do
{
*(ulong *)op = *(ulong *)ip; op += 8; ip += 8;
} while (op < cpy);; ip -= (op - cpy); op = cpy;
// get offset
{ r = (cpy) - *(ushort *)ip; }; ip += 2;
if (r < decompressedBuffer)
{
goto _output_error;
}
// get matchLength
if ((length = (int)(token & LZ4Util.ML_MASK)) == LZ4Util.ML_MASK)
{
for (; *ip == 255; length += 255)
{
ip++;
}
length += *ip++;
}
// copy repeated sequence
if (op - r < STEPSIZE)
{
var dec2 = dec2Ptr[(int)(op - r)];
*op++ = *r++;
*op++ = *r++;
*op++ = *r++;
*op++ = *r++;
r -= dec[op - r];
*(uint *)op = *(uint *)r; op += STEPSIZE - 4;
r -= dec2;
}
else
{
*(ulong *)op = *(ulong *)r; op += 8; r += 8;;
}
cpy = op + length - (STEPSIZE - 4);
if (cpy > oend - LZ4Util.COPYLENGTH)
{
if (cpy > oend)
{
goto _output_error;
}
if (op < (oend - LZ4Util.COPYLENGTH))
{
do
{
*(ulong *)op = *(ulong *)r; op += 8; r += 8;
} while (op < (oend - LZ4Util.COPYLENGTH));
}
;
while (op < cpy)
{
*op++ = *r++;
}
op = cpy;
if (op == oend)
{
break;
}
continue;
}
if (op < cpy)
{
do
{
*(ulong *)op = *(ulong *)r; op += 8; r += 8;
} while (op < cpy);
}
;
op = cpy; // correction
}
// end of decoding
return((int)(((byte *)ip) - compressed));
// write overflow error detected
_output_error:
return((int)(-(((byte *)ip) - compressed)));
}
}
// Note : this function is valid only if isize < LZ4_64KLIMIT
int Compress64K(byte *source, byte *dest, int isize, int maxOutputSize)
{
fixed(byte *hashTablePtr = m_HashTable)
fixed(byte *deBruijnBytePos = DeBruijnBytePos)
{
Clear(hashTablePtr, sizeof(ushort) * HASHTABLESIZE * 2);
ushort *hashTable = (ushort *)hashTablePtr;
byte *ip = (byte *)source;
byte *anchor = ip;
byte *basep = ip;
byte *iend = ip + isize;
byte *mflimit = iend - MFLIMIT;
byte *matchlimit = (iend - LASTLITERALS);
byte *op = (byte *)dest;
byte *oend = dest + maxOutputSize;
int len, length;
const int skipStrength = SKIPSTRENGTH;
uint forwardH;
// Init
if (isize < MINLENGTH)
{
goto _last_literals;
}
// First Byte
ip++; forwardH = (((*(uint *)ip) * 2654435761U) >> ((MINMATCH * 8) - (HASH_LOG + 1)));
// Main Loop
for (; ;)
{
int findMatchAttempts = (int)(1U << skipStrength) + 3;
byte *forwardIp = ip;
byte *r;
byte *token;
// Find a match
do
{
uint h = forwardH;
int step = findMatchAttempts++ >> skipStrength;
ip = forwardIp;
forwardIp = ip + step;
if (forwardIp > mflimit)
{
goto _last_literals;
}
forwardH = (((*(uint *)forwardIp) * 2654435761U) >> ((MINMATCH * 8) - (HASH_LOG + 1)));
r = basep + hashTable[h];
hashTable[h] = (ushort)(ip - basep);
} while (*(uint *)r != *(uint *)ip);
// Catch up
while ((ip > anchor) && (r > (byte *)source) && (ip[-1] == r[-1]))
{
ip--; r--;
}
// Encode Literal Length
length = (int)(ip - anchor);
token = op++;
if (op + length + (2 + 1 + LASTLITERALS) + (length >> 8) >= oend)
{
return(0); // Check output limit
}
if (length >= (int)LZ4Util.RUN_MASK)
{
*token = (byte)(LZ4Util.RUN_MASK << LZ4Util.ML_BITS); len = (int)(length - LZ4Util.RUN_MASK); for (; len > 254; len -= 255)
{
*op++ = 255;
}
*op++ = (byte)len;
}
else
{
*token = (byte)(length << LZ4Util.ML_BITS);
}
// Copy Literals
{ byte *e = (op) + length; do
{
*(uint *)op = *(uint *)anchor; op += 4; anchor += 4;; *(uint *)op = *(uint *)anchor; op += 4; anchor += 4;;
} while (op < e);; op = e; };
_next_match:
// Encode Offset
*(ushort *)op = (ushort)(ip - r); op += 2;
// Start Counting
ip += MINMATCH; r += MINMATCH; // MinMatch verified
anchor = ip;
// while (ip<matchlimit-3)
// {
// if (*(uint *)r == *(uint *)ip) { ip+=4; r+=4; continue; }
// if (*(ushort *)r == *(ushort *)ip) { ip+=2; r+=2; }
// if (*r == *ip) ip++;
while (ip < matchlimit - (STEPSIZE - 1))
{
int diff = (int)(*(int *)(r) ^ *(int *)(ip));
if (diff == 0)
{
ip += STEPSIZE; r += STEPSIZE; continue;
}
ip += DeBruijnBytePos[((uint)((diff & -diff) * 0x077CB531U)) >> 27];;
goto _endCount;
}
if ((ip < (matchlimit - 1)) && (*(ushort *)r == *(ushort *)ip))
{
ip += 2; r += 2;
}
if ((ip < matchlimit) && (*r == *ip))
{
ip++;
}
_endCount:
len = (int)(ip - anchor);
//Encode MatchLength
if (len >= (int)LZ4Util.ML_MASK)
{
*token = (byte)(*token + LZ4Util.ML_MASK); len = (int)(len - LZ4Util.ML_MASK); for (; len > 509; len -= 510)
{
*op++ = 255; *op++ = 255;
}
if (len > 254)
{
len -= 255; *op++ = 255;
}
*op++ = (byte)len;
}
else
{
*token = (byte)(*token + len);
}
// Test end of chunk
if (ip > mflimit)
{
anchor = ip; break;
}
// Fill table
hashTable[(((*(uint *)ip - 2) * 2654435761U) >> ((MINMATCH * 8) - (HASH_LOG + 1)))] = (ushort)(ip - 2 - basep);
// Test next position
r = basep + hashTable[(((*(uint *)ip) * 2654435761U) >> ((MINMATCH * 8) - (HASH_LOG + 1)))];
hashTable[(((*(uint *)ip) * 2654435761U) >> ((MINMATCH * 8) - (HASH_LOG + 1)))] = (ushort)(ip - basep);
if (*(uint *)r == *(uint *)ip)
{
token = op++; *token = 0; goto _next_match;
}
// Prepare next loop
anchor = ip++;
forwardH = (((*(uint *)ip) * 2654435761U) >> ((MINMATCH * 8) - (HASH_LOG + 1)));
}
_last_literals:
{
int lastRun = (int)(iend - anchor);
if (((byte *)op - dest) + lastRun + 1 + ((lastRun) >> 8) >= maxOutputSize)
{
return(0);
}
if (lastRun >= (int)LZ4Util.RUN_MASK)
{
*op++ = (byte)(LZ4Util.RUN_MASK << LZ4Util.ML_BITS); lastRun -= (byte)LZ4Util.RUN_MASK; for (; lastRun > 254; lastRun -= 255)
{
*op++ = 255;
}
*op++ = (byte)lastRun;
}
else
{
*op++ = (byte)(lastRun << LZ4Util.ML_BITS);
}
LZ4Util.CopyMemory(op, anchor, iend - anchor);
op += iend - anchor;
}
return((int)(((byte *)op) - dest));
}
}
