public bool Decode( StreamManipulator input ) {
decode_loop:
for( ; ; ) {
switch( mode ) {
case LNUM:
lnum = input.PeekBits( 5 );
if( lnum < 0 ) {
return false;
}
lnum += 257;
input.DropBits( 5 );
// System.err.println("LNUM: "+lnum);
mode = DNUM;
goto case DNUM; // fall through
case DNUM:
dnum = input.PeekBits( 5 );
if( dnum < 0 ) {
return false;
}
dnum++;
input.DropBits( 5 );
// System.err.println("DNUM: "+dnum);
num = lnum + dnum;
litdistLens = new byte[ num ];
mode = BLNUM;
goto case BLNUM; // fall through
case BLNUM:
blnum = input.PeekBits( 4 );
if( blnum < 0 ) {
return false;
}
blnum += 4;
input.DropBits( 4 );
blLens = new byte[ 19 ];
ptr = 0;
// System.err.println("BLNUM: "+blnum);
mode = BLLENS;
goto case BLLENS; // fall through
case BLLENS:
while( ptr < blnum ) {
int len = input.PeekBits( 3 );
if( len < 0 ) {
return false;
}
input.DropBits( 3 );
// System.err.println("blLens["+BL_ORDER[ptr]+"]: "+len);
blLens[ BL_ORDER[ ptr ] ] = (byte)len;
ptr++;
}
blTree = new InflaterHuffmanTree( blLens );
blLens = null;
ptr = 0;
mode = LENS;
goto case LENS; // fall through
case LENS: {
int symbol;
while( ( ( symbol = blTree.GetSymbol( input ) ) & ~15 ) == 0 ) {
/* Normal case: symbol in [0..15] */
// System.err.println("litdistLens["+ptr+"]: "+symbol);
litdistLens[ ptr++ ] = lastLen = (byte)symbol;
if( ptr == num ) {
/* Finished */
return true;
}
}
/* need more input ? */
if( symbol < 0 ) {
return false;
}
/* otherwise repeat code */
if( symbol >= 17 ) {
/* repeat zero */
// System.err.println("repeating zero");
lastLen = 0;
} else {
if( ptr == 0 ) {
throw new BlubbZipBaseException();
}
}
repSymbol = symbol - 16;
}
mode = REPS;
goto case REPS; // fall through
case REPS: {
int bits = repBits[ repSymbol ];
int count = input.PeekBits( bits );
if( count < 0 ) {
return false;
}
input.DropBits( bits );
count += repMin[ repSymbol ];
// System.err.println("litdistLens repeated: "+count);
if( ptr + count > num ) {
throw new BlubbZipBaseException();
}
while( count-- > 0 ) {
litdistLens[ ptr++ ] = lastLen;
}
if( ptr == num ) {
/* Finished */
return true;
}
}
mode = LENS;
goto decode_loop;
}
}
}
/// <summary>
/// Reads the next symbol from input. The symbol is encoded using the
/// huffman tree.
/// </summary>
/// <param name="input">
/// input the input source.
/// </param>
/// <returns>
/// the next symbol, or -1 if not enough input is available.
/// </returns>
public int GetSymbol( StreamManipulator input ) {
int lookahead, symbol;
if( ( lookahead = input.PeekBits( 9 ) ) >= 0 ) {
if( ( symbol = tree[ lookahead ] ) >= 0 ) {
input.DropBits( symbol & 15 );
return symbol >> 4;
}
int subtree = -( symbol >> 4 );
int bitlen = symbol & 15;
if( ( lookahead = input.PeekBits( bitlen ) ) >= 0 ) {
symbol = tree[ subtree | ( lookahead >> 9 ) ];
input.DropBits( symbol & 15 );
return symbol >> 4;
} else {
int bits = input.AvailableBits;
lookahead = input.PeekBits( bits );
symbol = tree[ subtree | ( lookahead >> 9 ) ];
if( ( symbol & 15 ) <= bits ) {
input.DropBits( symbol & 15 );
return symbol >> 4;
} else {
return -1;
}
}
} else {
int bits = input.AvailableBits;
lookahead = input.PeekBits( bits );
symbol = tree[ lookahead ];
if( symbol >= 0 && ( symbol & 15 ) <= bits ) {
input.DropBits( symbol & 15 );
return symbol >> 4;
} else {
return -1;
}
}
}
