/// <summary>
/// Resets the inflater so that a new stream can be decompressed. All
/// pending input and output will be discarded.
/// </summary>
public void Reset()
{
mode = nowrap ? DECODE_BLOCKS : DECODE_HEADER;
totalIn = totalOut = 0;
input.Reset();
outputWindow.Reset();
dynHeader = null;
litlenTree = null;
distTree = null;
isLastBlock = false;
adler.Reset();
}
/// <summary>
/// Decodes the deflated stream.
/// </summary>
/// <returns>
/// false if more input is needed, or if finished.
/// </returns>
/// <exception cref="System.FormatException">
/// DataFormatException, if deflated stream is invalid.
/// </exception>
private bool Decode()
{
switch (mode)
{
case DECODE_HEADER:
return(DecodeHeader());
case DECODE_DICT:
return(DecodeDict());
case DECODE_CHKSUM:
return(DecodeChksum());
case DECODE_BLOCKS:
if (isLastBlock)
{
if (nowrap)
{
mode = FINISHED;
return(false);
}
else
{
input.SkipToByteBoundary();
neededBits = 32;
mode = DECODE_CHKSUM;
return(true);
}
}
int type = input.PeekBits(3);
if (type < 0)
{
return(false);
}
input.DropBits(3);
if ((type & 1) != 0)
{
isLastBlock = true;
}
switch (type >> 1)
{
case DeflaterConstants.STORED_BLOCK:
input.SkipToByteBoundary();
mode = DECODE_STORED_LEN1;
break;
case DeflaterConstants.STATIC_TREES:
litlenTree = InflaterHuffmanTree.defLitLenTree;
distTree = InflaterHuffmanTree.defDistTree;
mode = DECODE_HUFFMAN;
break;
case DeflaterConstants.DYN_TREES:
dynHeader = new InflaterDynHeader();
mode = DECODE_DYN_HEADER;
break;
default:
throw new FormatException("Unknown block type " + type);
}
return(true);
case DECODE_STORED_LEN1: {
if ((uncomprLen = input.PeekBits(16)) < 0)
{
return(false);
}
input.DropBits(16);
mode = DECODE_STORED_LEN2;
}
goto case DECODE_STORED_LEN2; /* fall through */
case DECODE_STORED_LEN2: {
int nlen = input.PeekBits(16);
if (nlen < 0)
{
return(false);
}
input.DropBits(16);
if (nlen != (uncomprLen ^ 0xffff))
{
throw new FormatException("broken uncompressed block");
}
mode = DECODE_STORED;
}
goto case DECODE_STORED; /* fall through */
case DECODE_STORED: {
int more = outputWindow.CopyStored(input, uncomprLen);
uncomprLen -= more;
if (uncomprLen == 0)
{
mode = DECODE_BLOCKS;
return(true);
}
return(!input.NeedsInput());
}
case DECODE_DYN_HEADER:
if (!dynHeader.Decode(input))
{
return(false);
}
litlenTree = dynHeader.BuildLitLenTree();
distTree = dynHeader.BuildDistTree();
mode = DECODE_HUFFMAN;
goto case DECODE_HUFFMAN; /* fall through */
case DECODE_HUFFMAN:
case DECODE_HUFFMAN_LENBITS:
case DECODE_HUFFMAN_DIST:
case DECODE_HUFFMAN_DISTBITS:
return(DecodeHuffman());
case FINISHED:
return(false);
default:
throw new FormatException();
}
}
/// <summary>
/// Decodes the deflated stream.
/// </summary>
/// <returns>
/// false if more input is needed, or if finished.
/// </returns>
/// <exception cref="System.FormatException">
/// DataFormatException, if deflated stream is invalid.
/// </exception>
private bool Decode()
{
switch (mode) {
case DECODE_HEADER:
return DecodeHeader();
case DECODE_DICT:
return DecodeDict();
case DECODE_CHKSUM:
return DecodeChksum();
case DECODE_BLOCKS:
if (isLastBlock) {
if (nowrap) {
mode = FINISHED;
return false;
} else {
input.SkipToByteBoundary();
neededBits = 32;
mode = DECODE_CHKSUM;
return true;
}
}
int type = input.PeekBits(3);
if (type < 0) {
return false;
}
input.DropBits(3);
if ((type & 1) != 0) {
isLastBlock = true;
}
switch (type >> 1) {
case DeflaterConstants.STORED_BLOCK:
input.SkipToByteBoundary();
mode = DECODE_STORED_LEN1;
break;
case DeflaterConstants.STATIC_TREES:
litlenTree = InflaterHuffmanTree.defLitLenTree;
distTree = InflaterHuffmanTree.defDistTree;
mode = DECODE_HUFFMAN;
break;
case DeflaterConstants.DYN_TREES:
dynHeader = new InflaterDynHeader();
mode = DECODE_DYN_HEADER;
break;
default:
throw new FormatException("Unknown block type "+type);
}
return true;
case DECODE_STORED_LEN1: {
if ((uncomprLen = input.PeekBits(16)) < 0) {
return false;
}
input.DropBits(16);
mode = DECODE_STORED_LEN2;
}
goto case DECODE_STORED_LEN2; /* fall through */
case DECODE_STORED_LEN2: {
int nlen = input.PeekBits(16);
if (nlen < 0) {
return false;
}
input.DropBits(16);
if (nlen != (uncomprLen ^ 0xffff)) {
throw new FormatException("broken uncompressed block");
}
mode = DECODE_STORED;
}
goto case DECODE_STORED;/* fall through */
case DECODE_STORED: {
int more = outputWindow.CopyStored(input, uncomprLen);
uncomprLen -= more;
if (uncomprLen == 0) {
mode = DECODE_BLOCKS;
return true;
}
return !input.IsNeedingInput;
}
case DECODE_DYN_HEADER:
if (!dynHeader.Decode(input)) {
return false;
}
litlenTree = dynHeader.BuildLitLenTree();
distTree = dynHeader.BuildDistTree();
mode = DECODE_HUFFMAN;
goto case DECODE_HUFFMAN; /* fall through */
case DECODE_HUFFMAN:
case DECODE_HUFFMAN_LENBITS:
case DECODE_HUFFMAN_DIST:
case DECODE_HUFFMAN_DISTBITS:
return DecodeHuffman();
case FINISHED:
return false;
default:
throw new FormatException();
}
}
/// <summary>
/// Resets the inflater so that a new stream can be decompressed. All
/// pending input and output will be discarded.
/// </summary>
public void Reset()
{
mode = nowrap ? DECODE_BLOCKS : DECODE_HEADER;
totalIn = totalOut = 0;
input.Reset();
outputWindow.Reset();
dynHeader = null;
litlenTree = null;
distTree = null;
isLastBlock = false;
adler.Reset();
}
