private bool?DecodeTop(ref bool endOfBlock, ref int freeBytes)
{
int nextSymbol = this.literalLengthTree.GetNextSymbol(this.input);
if (nextSymbol < 0)
{
return(new bool?(false));
}
if (nextSymbol >= 256)
{
if (nextSymbol == 256)
{
endOfBlock = true;
this.state = DeflateDecompressor.DecompressorState.ReadingBFinal;
return(new bool?(true));
}
this.DecodeDistance(ref nextSymbol);
this.state = DeflateDecompressor.DecompressorState.HaveInitialLength;
}
else
{
this.output.AddByte((byte)nextSymbol);
--freeBytes;
}
return(new bool?());
}
private bool ReadTreeCodes()
{
while (this.loopCounter < this.codeArraySize)
{
if (this.state == DeflateDecompressor.DecompressorState.ReadingTreeCodesBefore)
{
this.lengthCode = this.codeLengthTree.GetNextSymbol(this.input);
if (this.lengthCode < 0)
{
return(false);
}
}
if (this.lengthCode > 15)
{
if (!this.input.CheckAvailable(7))
{
this.state = DeflateDecompressor.DecompressorState.ReadingTreeCodesAfter;
return(false);
}
this.SetPreviousCode();
}
else
{
this.codeList[this.loopCounter++] = (byte)this.lengthCode;
}
this.state = DeflateDecompressor.DecompressorState.ReadingTreeCodesBefore;
}
this.SetTreeCodes();
this.state = DeflateDecompressor.DecompressorState.DecodeTop;
return(true);
}
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 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 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 bool?DecodeFullLength()
{
if (this.blockType != DeflateDecompressor.BlockType.Dynamic)
{
this.distanceCode = this.input.GetBits(5);
if (this.distanceCode >= 0)
{
this.distanceCode = (int)DeflateDecompressor.staticDistanceTreeTable[this.distanceCode];
}
}
else
{
this.distanceCode = this.distanceTree.GetNextSymbol(this.input);
}
if (this.distanceCode < 0)
{
return(new bool?(false));
}
this.state = DeflateDecompressor.DecompressorState.HaveDistCode;
return(new bool?());
}
private bool Decode()
{
if (this.state == DeflateDecompressor.DecompressorState.ReadingBFinal)
{
if (!this.input.CheckAvailable(1))
{
return(false);
}
this.bfinal = this.input.GetBits(1);
this.state = DeflateDecompressor.DecompressorState.ReadingBType;
}
if (this.state == DeflateDecompressor.DecompressorState.ReadingBType)
{
if (!this.input.CheckAvailable(2))
{
return(false);
}
this.ProcessBlockType();
}
return(this.CheckDecodeState());
}
private bool?DecodeDistanceCode(ref int freeBytes)
{
int distance;
if (this.distanceCode <= 3)
{
distance = this.distanceCode + 1;
}
else
{
this.extraBits = this.distanceCode - 2 >> 1;
int bits = this.input.GetBits(this.extraBits);
if (bits < 0)
{
return(new bool?(false));
}
distance = DeflateDecompressor.distanceBasePosition[this.distanceCode] + bits;
}
this.output.Copy(this.blockLength, distance);
freeBytes -= this.blockLength;
this.state = DeflateDecompressor.DecompressorState.DecodeTop;
return(new bool?());
}
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;
}
}
private void Reset()
{
this.state = DeflateDecompressor.DecompressorState.ReadingBFinal;
}
