static DecompressorHuffmanTree()
{
try
{
byte[] lengths;
int index;
lengths = new byte[288];
index = 0;
while (index < 144)
{
lengths[index++] = 8;
}
while (index < 256)
{
lengths[index++] = 9;
}
while (index < 280)
{
lengths[index++] = 7;
}
while (index < 288)
{
lengths[index++] = 8;
}
m_LengthTree = new DecompressorHuffmanTree(lengths);
lengths = new byte[32];
index = 0;
while (index < 32)
{
lengths[index++] = 5;
}
m_DistanceTree = new DecompressorHuffmanTree(lengths);
}
catch (Exception ex)
{
throw new Exception("DecompressorHuffmanTree: fixed trees generation failed", ex);
}
}
protected void DecodeDynHeader(out DecompressorHuffmanTree lengthTree, out DecompressorHuffmanTree distanceTree)
{
byte[] arrDecoderCodeLengths;
byte[] arrResultingCodeLengths;
byte bLastSymbol = 0;
int iLengthsCount = ReadBits(5);
int iDistancesCount = ReadBits(5);
int iCodeLengthsCount = ReadBits(4);
if (iLengthsCount < 0 || iDistancesCount < 0 || iCodeLengthsCount < 0)
throw new FormatException("Wrong dynamic huffman codes.");
iLengthsCount += 257;
iDistancesCount += 1;
int iResultingCodeLengthsCount = iLengthsCount + iDistancesCount;
arrResultingCodeLengths = new byte[iResultingCodeLengthsCount];
arrDecoderCodeLengths = new byte[19];
iCodeLengthsCount += 4;
int iCurrentCode = 0;
while (iCurrentCode < iCodeLengthsCount)
{
int len = ReadBits(3);
if (len < 0)
throw new FormatException("Wrong dynamic huffman codes.");
arrDecoderCodeLengths[BitUtils.DEF_HUFFMAN_DYNTREE_CODELENGTHS_ORDER[iCurrentCode++]] =
(byte)len;
}
DecompressorHuffmanTree treeInternalDecoder = new
DecompressorHuffmanTree(arrDecoderCodeLengths);
iCurrentCode = 0;
for (; ; )
{
int symbol;
bool bNeedBreak = false;
while (((symbol = treeInternalDecoder.UnpackSymbol(this)) & ~15) == 0)
{
arrResultingCodeLengths[iCurrentCode++] = bLastSymbol = (byte)symbol;
if (iCurrentCode == iResultingCodeLengthsCount)
{
bNeedBreak = true;
break;
}
}
if (bNeedBreak) break;
if (symbol < 0)
throw new FormatException("Wrong dynamic huffman codes.");
if (symbol >= 17)
{
bLastSymbol = 0;
}
else if (iCurrentCode == 0)
{
throw new FormatException("Wrong dynamic huffman codes.");
}
int m_iRepSymbol = symbol - 16;
int bits = DEF_HUFFMAN_DYNTREE_REPEAT_BITS[m_iRepSymbol];
int count = ReadBits(bits);
if (count < 0)
throw new FormatException("Wrong dynamic huffman codes.");
count += DEF_HUFFMAN_DYNTREE_REPEAT_MINIMUMS[m_iRepSymbol];
if (iCurrentCode + count > iResultingCodeLengthsCount)
throw new FormatException("Wrong dynamic huffman codes.");
while (count-- > 0)
{
arrResultingCodeLengths[iCurrentCode++] = bLastSymbol;
}
if (iCurrentCode == iResultingCodeLengthsCount) break;
}
byte[] tempArray = new byte[iLengthsCount];
Array.Copy(arrResultingCodeLengths, 0, tempArray, 0, iLengthsCount);
lengthTree = new DecompressorHuffmanTree(tempArray);
tempArray = new byte[iDistancesCount];
Array.Copy(arrResultingCodeLengths, iLengthsCount, tempArray, 0, iDistancesCount);
distanceTree = new DecompressorHuffmanTree(tempArray);
}
protected bool DecodeBlockHeader()
{
if (!m_bCanReadNextBlock)
{
return false;
}
int bFinalBlock = ReadBits(1);
if (bFinalBlock == -1)
{
return false;
}
int blockType = ReadBits(2);
if (blockType == -1)
{
return false;
}
m_bCanReadNextBlock = (bFinalBlock == 0);
switch (blockType)
{
case 0:
m_bReadingUncompressed = true;
SkipToBoundary();
int length = ReadInt16Inverted();
int lengthComplement = ReadInt16Inverted();
if (length != (lengthComplement ^ 0xffff))
throw new FormatException("Wrong block length.");
if (length > UInt16.MaxValue)
throw new FormatException("Uncompressed block length can not be more than 65535.");
m_UncompressedDataLength = length;
m_CurrentLengthTree = null;
m_CurrentDistanceTree = null;
break;
case 1:
m_bReadingUncompressed = false;
m_UncompressedDataLength = -1;
m_CurrentLengthTree = DecompressorHuffmanTree.LengthTree;
m_CurrentDistanceTree = DecompressorHuffmanTree.DistanceTree;
break;
case 2:
m_bReadingUncompressed = false;
m_UncompressedDataLength = -1;
DecodeDynHeader(out m_CurrentLengthTree, out m_CurrentDistanceTree);
break;
default:
throw new FormatException("Wrong block type.");
}
return true;
}
