private bool DecodeDynamicBlockHeader()
{
switch (this.state)
{
case InflaterState.ReadingNumLitCodes:
this.literalLengthCodeCount = this.input.GetBits(5);
if (this.literalLengthCodeCount < 0)
{
return(false);
}
this.literalLengthCodeCount += 257;
this.state = InflaterState.ReadingNumDistCodes;
goto case InflaterState.ReadingNumDistCodes;
case InflaterState.ReadingNumDistCodes:
this.distanceCodeCount = this.input.GetBits(5);
if (this.distanceCodeCount < 0)
{
return(false);
}
++this.distanceCodeCount;
this.state = InflaterState.ReadingNumCodeLengthCodes;
goto case InflaterState.ReadingNumCodeLengthCodes;
case InflaterState.ReadingNumCodeLengthCodes:
this.codeLengthCodeCount = this.input.GetBits(4);
if (this.codeLengthCodeCount < 0)
{
return(false);
}
this.codeLengthCodeCount += 4;
this.loopCounter = 0;
this.state = InflaterState.ReadingCodeLengthCodes;
goto case InflaterState.ReadingCodeLengthCodes;
case InflaterState.ReadingCodeLengthCodes:
for (; this.loopCounter < this.codeLengthCodeCount; ++this.loopCounter)
{
int bits = this.input.GetBits(3);
if (bits < 0)
{
return(false);
}
this.codeLengthTreeCodeLength[(int)Inflater.codeOrder[this.loopCounter]] = (byte)bits;
}
for (int codeLengthCodeCount = this.codeLengthCodeCount; codeLengthCodeCount < Inflater.codeOrder.Length; ++codeLengthCodeCount)
{
this.codeLengthTreeCodeLength[(int)Inflater.codeOrder[codeLengthCodeCount]] = (byte)0;
}
this.codeLengthTree = new HuffmanTree(this.codeLengthTreeCodeLength);
this.codeArraySize = this.literalLengthCodeCount + this.distanceCodeCount;
this.loopCounter = 0;
this.state = InflaterState.ReadingTreeCodesBefore;
goto case InflaterState.ReadingTreeCodesBefore;
case InflaterState.ReadingTreeCodesBefore:
case InflaterState.ReadingTreeCodesAfter:
while (this.loopCounter < this.codeArraySize)
{
if (this.state == InflaterState.ReadingTreeCodesBefore && (this.lengthCode = this.codeLengthTree.GetNextSymbol(this.input)) < 0)
{
return(false);
}
if (this.lengthCode <= 15)
{
this.codeList[this.loopCounter++] = (byte)this.lengthCode;
}
else
{
if (!this.input.EnsureBitsAvailable(7))
{
this.state = InflaterState.ReadingTreeCodesAfter;
return(false);
}
if (this.lengthCode == 16)
{
if (this.loopCounter == 0)
{
throw new InvalidDataException();
}
byte code = this.codeList[this.loopCounter - 1];
int num = this.input.GetBits(2) + 3;
if (this.loopCounter + num > this.codeArraySize)
{
throw new InvalidDataException();
}
for (int index = 0; index < num; ++index)
{
this.codeList[this.loopCounter++] = code;
}
}
else if (this.lengthCode == 17)
{
int num = this.input.GetBits(3) + 3;
if (this.loopCounter + num > this.codeArraySize)
{
throw new InvalidDataException();
}
for (int index = 0; index < num; ++index)
{
this.codeList[this.loopCounter++] = (byte)0;
}
}
else
{
int num = this.input.GetBits(7) + 11;
if (this.loopCounter + num > this.codeArraySize)
{
throw new InvalidDataException();
}
for (int index = 0; index < num; ++index)
{
this.codeList[this.loopCounter++] = (byte)0;
}
}
}
this.state = InflaterState.ReadingTreeCodesBefore;
}
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)
{
throw new InvalidDataException();
}
this.literalLengthTree = new HuffmanTree(codeLengths1);
this.distanceTree = new HuffmanTree(codeLengths2);
this.state = InflaterState.DecodeTop;
return(true);
default:
Debug.Assert(false, "check why we are here!");
throw new InvalidDataException(SR.GetString("Unknown state"));
}
}
private bool Decode()
{
bool flag1 = false;
if (this.Finished())
{
return(true);
}
if (this.hasFormatReader)
{
if (this.state == InflaterState.ReadingHeader)
{
if (!this.formatReader.ReadHeader(this.input))
{
return(false);
}
this.state = InflaterState.ReadingBFinal;
}
else if (this.state == InflaterState.StartReadingFooter || this.state == InflaterState.ReadingFooter)
{
if (!this.formatReader.ReadFooter(this.input))
{
return(false);
}
this.state = InflaterState.VerifyingFooter;
return(true);
}
}
if (this.state == InflaterState.ReadingBFinal)
{
if (!this.input.EnsureBitsAvailable(1))
{
return(false);
}
this.bfinal = this.input.GetBits(1);
this.state = InflaterState.ReadingBType;
}
if (this.state == InflaterState.ReadingBType)
{
if (!this.input.EnsureBitsAvailable(2))
{
this.state = InflaterState.ReadingBType;
return(false);
}
this.blockType = (BlockType)this.input.GetBits(2);
if (this.blockType == BlockType.Dynamic)
{
this.state = InflaterState.ReadingNumLitCodes;
}
else if (this.blockType == BlockType.Static)
{
this.literalLengthTree = HuffmanTree.StaticLiteralLengthTree;
this.distanceTree = HuffmanTree.StaticDistanceTree;
this.state = InflaterState.DecodeTop;
}
else
{
if (this.blockType != BlockType.Uncompressed)
{
throw new InvalidDataException(SR.GetString("Unknown block type"));
}
this.state = InflaterState.UncompressedAligning;
}
}
bool flag2;
if (this.blockType == BlockType.Dynamic)
{
flag2 = this.state >= InflaterState.DecodeTop ? this.DecodeBlock(out flag1) : this.DecodeDynamicBlockHeader();
}
else if (this.blockType == BlockType.Static)
{
flag2 = this.DecodeBlock(out flag1);
}
else
{
if (this.blockType != BlockType.Uncompressed)
{
throw new InvalidDataException(SR.GetString("Unknown block type"));
}
flag2 = this.DecodeUncompressedBlock(out flag1);
}
if (flag1 && (uint)this.bfinal > 0U)
{
this.state = !this.hasFormatReader ? InflaterState.Done : InflaterState.StartReadingFooter;
}
return(flag2);
}
