private bool CheckDecodeState()
{
bool endOfBlock = false;
bool flag;
if (this.blockType == DeflateDecompressor.BlockType.Dynamic)
{
flag = this.state < DeflateDecompressor.DecompressorState.DecodeTop ? this.DecodeDynamicBlockHeader() : this.DecodeBlock(out endOfBlock);
}
else if (this.blockType != DeflateDecompressor.BlockType.Static)
{
if (this.blockType != DeflateDecompressor.BlockType.Stored)
{
DeflateDecompressor.ThrowUnknownBlockType();
}
flag = this.DecodeUncompressedBlock(out endOfBlock);
}
else
{
flag = this.DecodeBlock(out endOfBlock);
}
if (endOfBlock && this.bfinal != 0)
{
this.state = DeflateDecompressor.DecompressorState.Done;
}
return(flag);
}
private void SetPreviousCode()
{
byte num1 = 0;
int num2;
if (this.lengthCode == 16)
{
if (this.loopCounter == 0)
{
DeflateDecompressor.ThrowInvalidDataGeneric();
}
num1 = this.codeList[this.loopCounter - 1];
num2 = this.input.GetBits(2) + 3;
}
else
{
num2 = this.lengthCode == 17 ? this.input.GetBits(3) + 3 : this.input.GetBits(7) + 11;
}
if (this.loopCounter + num2 > this.codeArraySize)
{
DeflateDecompressor.ThrowInvalidDataGeneric();
}
for (int index = 0; index < num2; ++index)
{
this.codeList[this.loopCounter++] = num1;
}
}
private bool DecodeDynamicBlockHeader()
{
switch (this.state)
{
case DeflateDecompressor.DecompressorState.ReadingNumLitCodes:
this.literalLengthCodeCount = this.input.GetBits(5);
if (this.literalLengthCodeCount < 0)
{
return(false);
}
this.literalLengthCodeCount += 257;
this.state = DeflateDecompressor.DecompressorState.ReadingNumDistCodes;
goto case DeflateDecompressor.DecompressorState.ReadingNumDistCodes;
case DeflateDecompressor.DecompressorState.ReadingNumDistCodes:
this.distanceCodeCount = this.input.GetBits(5);
if (this.distanceCodeCount < 0)
{
return(false);
}
++this.distanceCodeCount;
this.state = DeflateDecompressor.DecompressorState.ReadingNumCodeLengthCodes;
goto case DeflateDecompressor.DecompressorState.ReadingNumCodeLengthCodes;
case DeflateDecompressor.DecompressorState.ReadingNumCodeLengthCodes:
this.codeLengthCodeCount = this.input.GetBits(4);
if (this.codeLengthCodeCount < 0)
{
return(false);
}
this.codeLengthCodeCount += 4;
this.loopCounter = 0;
this.state = DeflateDecompressor.DecompressorState.ReadingCodeLengthCodes;
goto case DeflateDecompressor.DecompressorState.ReadingCodeLengthCodes;
case DeflateDecompressor.DecompressorState.ReadingCodeLengthCodes:
if (!this.DecodeDynamicCodes())
{
return(false);
}
this.state = DeflateDecompressor.DecompressorState.ReadingTreeCodesBefore;
goto case DeflateDecompressor.DecompressorState.ReadingTreeCodesBefore;
case DeflateDecompressor.DecompressorState.ReadingTreeCodesBefore:
case DeflateDecompressor.DecompressorState.ReadingTreeCodesAfter:
return(this.ReadTreeCodes());
default:
DeflateDecompressor.ThrowUnknownState();
return(true);
}
}
private void SetTreeCodes()
{
byte[] codeLengths1 = new byte[288];
byte[] codeLengths2 = new byte[32];
Array.Copy((Array)this.codeList, (Array)codeLengths1, this.literalLengthCodeCount);
Array.Copy((Array)this.codeList, this.literalLengthCodeCount, (Array)codeLengths2, 0, this.distanceCodeCount);
if (codeLengths1[256] == (byte)0)
{
DeflateDecompressor.ThrowInvalidDataGeneric();
}
this.literalLengthTree = new InflateTree(codeLengths1);
this.distanceTree = new InflateTree(codeLengths2);
}
private bool DecodeBlock(out bool endOfBlock)
{
int freeBytes = this.output.FreeBytes;
endOfBlock = false;
while (freeBytes > 258)
{
switch (this.state)
{
case DeflateDecompressor.DecompressorState.DecodeTop:
bool?nullable1 = this.DecodeTop(ref endOfBlock, ref freeBytes);
if (nullable1.HasValue)
{
return(nullable1.Value);
}
continue;
case DeflateDecompressor.DecompressorState.HaveInitialLength:
bool?nullable2 = this.DecodeInitialLength();
if (nullable2.HasValue)
{
return(nullable2.Value);
}
continue;
case DeflateDecompressor.DecompressorState.HaveFullLength:
bool?nullable3 = this.DecodeFullLength();
if (nullable3.HasValue)
{
return(nullable3.Value);
}
continue;
case DeflateDecompressor.DecompressorState.HaveDistCode:
bool?nullable4 = this.DecodeDistanceCode(ref freeBytes);
if (nullable4.HasValue)
{
return(nullable4.Value);
}
continue;
default:
DeflateDecompressor.ThrowUnknownState();
continue;
}
}
return(true);
}
private bool?DecodeInitialLength()
{
if (this.extraBits > 0)
{
int bits = this.input.GetBits(this.extraBits);
if (bits < 0)
{
return(new bool?(false));
}
if (this.blockLength < 0 || this.blockLength >= DeflateDecompressor.lengthBase.Length)
{
DeflateDecompressor.ThrowInvalidData();
}
this.blockLength = DeflateDecompressor.lengthBase[this.blockLength] + bits;
}
this.state = DeflateDecompressor.DecompressorState.HaveFullLength;
return(new bool?());
}
private void DecodeDistance(ref int nextSymbol)
{
nextSymbol -= 257;
if (nextSymbol < 8)
{
nextSymbol += 3;
this.extraBits = 0;
}
else if (nextSymbol != 28)
{
if (nextSymbol < 0 || nextSymbol >= Tree.ExtraLengthBits.Length)
{
DeflateDecompressor.ThrowInvalidData();
}
this.extraBits = Tree.ExtraLengthBits[nextSymbol];
}
else
{
nextSymbol = 258;
this.extraBits = 0;
}
this.blockLength = nextSymbol;
}
private bool DecodeUncompressedBlock(out bool endOfBlock)
{
endOfBlock = false;
while (this.state != DeflateDecompressor.DecompressorState.DecodingUncompressed)
{
switch (this.state)
{
case DeflateDecompressor.DecompressorState.UncompressedAligning:
this.input.SkipToByteBoundary();
this.state = DeflateDecompressor.DecompressorState.UncompressedByte1;
continue;
case DeflateDecompressor.DecompressorState.UncompressedByte1:
case DeflateDecompressor.DecompressorState.UncompressedByte2:
case DeflateDecompressor.DecompressorState.UncompressedByte3:
case DeflateDecompressor.DecompressorState.UncompressedByte4:
if (!this.DecodeBits())
{
return(false);
}
continue;
default:
DeflateDecompressor.ThrowUnknownState();
continue;
}
}
this.blockLength -= this.output.ReadInput(this.input, this.blockLength);
if (this.blockLength != 0)
{
return(this.output.FreeBytes == 0);
}
this.state = DeflateDecompressor.DecompressorState.ReadingBFinal;
endOfBlock = true;
return(true);
}
private void ProcessBlockType()
{
this.blockType = (DeflateDecompressor.BlockType) this.input.GetBits(2);
switch (this.blockType)
{
case DeflateDecompressor.BlockType.Stored:
this.state = DeflateDecompressor.DecompressorState.UncompressedAligning;
break;
case DeflateDecompressor.BlockType.Static:
this.literalLengthTree = InflateTree.StaticLiteralLengthTree;
this.distanceTree = InflateTree.StaticDistanceTree;
this.state = DeflateDecompressor.DecompressorState.DecodeTop;
break;
case DeflateDecompressor.BlockType.Dynamic:
this.state = DeflateDecompressor.DecompressorState.ReadingNumLitCodes;
break;
default:
DeflateDecompressor.ThrowUnknownBlockType();
break;
}
}
