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#region License
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/* LzxDecoder.cs - C# port of libmsport's lzxd.c
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* Copyright 2003-2004 Stuart Caie
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* Copyright 2011 Ali Scissons
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*
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* Released under a dual MSPL/LGPL license.
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* See lzxdecoder.LICENSE for details.
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*/
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#endregion
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#region Using Statements
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using System;
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#endregion
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namespace Microsoft.Xna.Framework.Content
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{
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using System.IO;
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class LzxDecoder
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{
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public static uint[] position_base = null;
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public static byte[] extra_bits = null;
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private LzxState m_state;
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public LzxDecoder (int window)
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{
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uint wndsize = (uint)(1 << window);
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int posn_slots;
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// Setup proper exception.
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if(window < 15 || window > 21) throw new UnsupportedWindowSizeRange();
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// Let's initialize our state.
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m_state = new LzxState();
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m_state.actual_size = 0;
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m_state.window = new byte[wndsize];
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for(int i = 0; i < wndsize; i++) m_state.window[i] = 0xDC;
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m_state.actual_size = wndsize;
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m_state.window_size = wndsize;
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m_state.window_posn = 0;
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// Initialize static tables.
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if(extra_bits == null)
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{
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extra_bits = new byte[52];
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for(int i = 0, j = 0; i <= 50; i += 2)
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{
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extra_bits[i] = extra_bits[i+1] = (byte)j;
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if ((i != 0) && (j < 17)) j++;
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}
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}
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if(position_base == null)
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{
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position_base = new uint[51];
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for(int i = 0, j = 0; i <= 50; i++)
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{
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position_base[i] = (uint)j;
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j += 1 << extra_bits[i];
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}
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}
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// Calculate required position slots.
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if(window == 20) posn_slots = 42;
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else if(window == 21) posn_slots = 50;
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else posn_slots = window << 1;
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m_state.R0 = m_state.R1 = m_state.R2 = 1;
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m_state.main_elements = (ushort)(LzxConstants.NUM_CHARS + (posn_slots << 3));
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m_state.header_read = 0;
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m_state.frames_read = 0;
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m_state.block_remaining = 0;
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m_state.block_type = LzxConstants.BLOCKTYPE.INVALID;
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m_state.intel_curpos = 0;
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m_state.intel_started = 0;
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m_state.PRETREE_table = new ushort[(1 << LzxConstants.PRETREE_TABLEBITS) + (LzxConstants.PRETREE_MAXSYMBOLS << 1)];
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m_state.PRETREE_len = new byte[LzxConstants.PRETREE_MAXSYMBOLS + LzxConstants.LENTABLE_SAFETY];
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m_state.MAINTREE_table = new ushort[(1 << LzxConstants.MAINTREE_TABLEBITS) + (LzxConstants.MAINTREE_MAXSYMBOLS << 1)];
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m_state.MAINTREE_len = new byte[LzxConstants.MAINTREE_MAXSYMBOLS + LzxConstants.LENTABLE_SAFETY];
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m_state.LENGTH_table = new ushort[(1 << LzxConstants.LENGTH_TABLEBITS) + (LzxConstants.LENGTH_MAXSYMBOLS << 1)];
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m_state.LENGTH_len = new byte[LzxConstants.LENGTH_MAXSYMBOLS + LzxConstants.LENTABLE_SAFETY];
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m_state.ALIGNED_table = new ushort[(1 << LzxConstants.ALIGNED_TABLEBITS) + (LzxConstants.ALIGNED_MAXSYMBOLS << 1)];
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m_state.ALIGNED_len = new byte[LzxConstants.ALIGNED_MAXSYMBOLS + LzxConstants.LENTABLE_SAFETY];
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// Initialize tables to 0 (because deltas will be applied to them).
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for(int i = 0; i < LzxConstants.MAINTREE_MAXSYMBOLS; i++) m_state.MAINTREE_len[i] = 0;
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for(int i = 0; i < LzxConstants.LENGTH_MAXSYMBOLS; i++) m_state.LENGTH_len[i] = 0;
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}
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public int Decompress(Stream inData, int inLen, Stream outData, int outLen)
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{
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BitBuffer bitbuf = new BitBuffer(inData);
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long startpos = inData.Position;
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long endpos = inData.Position + inLen;
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byte[] window = m_state.window;
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uint window_posn = m_state.window_posn;
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uint window_size = m_state.window_size;
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uint R0 = m_state.R0;
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uint R1 = m_state.R1;
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uint R2 = m_state.R2;
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uint i, j;
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int togo = outLen, this_run, main_element, match_length, match_offset, length_footer, extra, verbatim_bits;
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int rundest, runsrc, copy_length, aligned_bits;
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bitbuf.InitBitStream();
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// Read header if necessary.
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if(m_state.header_read == 0)
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{
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uint intel = bitbuf.ReadBits(1);
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if(intel != 0)
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{
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// Read the filesize.
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i = bitbuf.ReadBits(16); j = bitbuf.ReadBits(16);
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m_state.intel_filesize = (int)((i << 16) | j);
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}
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m_state.header_read = 1;
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}
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// Main decoding loop.
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while(togo > 0)
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{
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// last block finished, new block expected.
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if(m_state.block_remaining == 0)
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{
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// TODO may screw something up here
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if(m_state.block_type == LzxConstants.BLOCKTYPE.UNCOMPRESSED) {
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if((m_state.block_length & 1) == 1) inData.ReadByte(); /* realign bitstream to word */
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bitbuf.InitBitStream();
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}
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m_state.block_type = (LzxConstants.BLOCKTYPE)bitbuf.ReadBits(3);
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i = bitbuf.ReadBits(16);
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j = bitbuf.ReadBits(8);
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m_state.block_remaining = m_state.block_length = (uint)((i << 8) | j);
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switch(m_state.block_type)
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{
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case LzxConstants.BLOCKTYPE.ALIGNED:
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for(i = 0, j = 0; i < 8; i++) { j = bitbuf.ReadBits(3); m_state.ALIGNED_len[i] = (byte)j; }
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MakeDecodeTable(LzxConstants.ALIGNED_MAXSYMBOLS, LzxConstants.ALIGNED_TABLEBITS,
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m_state.ALIGNED_len, m_state.ALIGNED_table);
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// Rest of aligned header is same as verbatim
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goto case LzxConstants.BLOCKTYPE.VERBATIM;
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case LzxConstants.BLOCKTYPE.VERBATIM:
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ReadLengths(m_state.MAINTREE_len, 0, 256, bitbuf);
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ReadLengths(m_state.MAINTREE_len, 256, m_state.main_elements, bitbuf);
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MakeDecodeTable(LzxConstants.MAINTREE_MAXSYMBOLS, LzxConstants.MAINTREE_TABLEBITS,
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m_state.MAINTREE_len, m_state.MAINTREE_table);
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if(m_state.MAINTREE_len[0xE8] != 0) m_state.intel_started = 1;
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ReadLengths(m_state.LENGTH_len, 0, LzxConstants.NUM_SECONDARY_LENGTHS, bitbuf);
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MakeDecodeTable(LzxConstants.LENGTH_MAXSYMBOLS, LzxConstants.LENGTH_TABLEBITS,
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m_state.LENGTH_len, m_state.LENGTH_table);
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break;
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case LzxConstants.BLOCKTYPE.UNCOMPRESSED:
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m_state.intel_started = 1; // Because we can't assume otherwise.
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bitbuf.EnsureBits(16); // Get up to 16 pad bits into the buffer.
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if(bitbuf.GetBitsLeft() > 16) inData.Seek(-2, SeekOrigin.Current); /* and align the bitstream! */
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byte hi, mh, ml, lo;
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lo = (byte)inData.ReadByte(); ml = (byte)inData.ReadByte(); mh = (byte)inData.ReadByte(); hi = (byte)inData.ReadByte();
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R0 = (uint)(lo | ml << 8 | mh << 16 | hi << 24);
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lo = (byte)inData.ReadByte(); ml = (byte)inData.ReadByte(); mh = (byte)inData.ReadByte(); hi = (byte)inData.ReadByte();
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R1 = (uint)(lo | ml << 8 | mh << 16 | hi << 24);
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lo = (byte)inData.ReadByte(); ml = (byte)inData.ReadByte(); mh = (byte)inData.ReadByte(); hi = (byte)inData.ReadByte();
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R2 = (uint)(lo | ml << 8 | mh << 16 | hi << 24);
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break;
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default:
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return -1; // TODO throw proper exception
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}
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}
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// Buffer exhaustion check.
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if(inData.Position > (startpos + inLen))
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{
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/* It's possible to have a file where the next run is less than
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* 16 bits in size. In this case, the READ_HUFFSYM() macro used
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* in building the tables will exhaust the buffer, so we should
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* allow for this, but not allow those accidentally read bits to
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* be used (so we check that there are at least 16 bits
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* remaining - in this boundary case they aren't really part of
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* the compressed data).
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*/
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if(inData.Position > (startpos+inLen+2) || bitbuf.GetBitsLeft() < 16) return -1; //TODO throw proper exception
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}
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while((this_run = (int)m_state.block_remaining) > 0 && togo > 0)
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{
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if(this_run > togo) this_run = togo;
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togo -= this_run;
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m_state.block_remaining -= (uint)this_run;
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// Apply 2^x-1 mask.
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window_posn &= window_size - 1;
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// Runs can't straddle the window wraparound.
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if((window_posn + this_run) > window_size)
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return -1; // TODO: throw proper exception
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switch(m_state.block_type)
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{
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case LzxConstants.BLOCKTYPE.VERBATIM:
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while(this_run > 0)
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{
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main_element = (int)ReadHuffSym(m_state.MAINTREE_table, m_state.MAINTREE_len,
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LzxConstants.MAINTREE_MAXSYMBOLS, LzxConstants.MAINTREE_TABLEBITS,
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bitbuf);
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if(main_element < LzxConstants.NUM_CHARS)
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{
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// Literal: 0 to NUM_CHARS-1.
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window[window_posn++] = (byte)main_element;
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this_run--;
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}
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else
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{
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// Match: NUM_CHARS + ((slot<<3) | length_header (3 bits))
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main_element -= LzxConstants.NUM_CHARS;
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match_length = main_element & LzxConstants.NUM_PRIMARY_LENGTHS;
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if(match_length == LzxConstants.NUM_PRIMARY_LENGTHS)
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{
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length_footer = (int)ReadHuffSym(m_state.LENGTH_table, m_state.LENGTH_len,
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LzxConstants.LENGTH_MAXSYMBOLS, LzxConstants.LENGTH_TABLEBITS,
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bitbuf);
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match_length += length_footer;
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}
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match_length += LzxConstants.MIN_MATCH;
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match_offset = main_element >> 3;
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if(match_offset > 2)
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{
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// Not repeated offset.
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if(match_offset != 3)
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{
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extra = extra_bits[match_offset];
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verbatim_bits = (int)bitbuf.ReadBits((byte)extra);
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match_offset = (int)position_base[match_offset] - 2 + verbatim_bits;
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}
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else
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{
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match_offset = 1;
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}
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// Update repeated offset LRU queue.
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R2 = R1; R1 = R0; R0 = (uint)match_offset;
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}
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else if(match_offset == 0)
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{
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match_offset = (int)R0;
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}
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else if(match_offset == 1)
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{
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match_offset = (int)R1;
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R1 = R0; R0 = (uint)match_offset;
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}
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else // match_offset == 2
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{
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match_offset = (int)R2;
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R2 = R0; R0 = (uint)match_offset;
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}
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rundest = (int)window_posn;
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this_run -= match_length;
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// Copy any wrapped around source data
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if(window_posn >= match_offset)
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{
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// No wrap
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runsrc = rundest - match_offset;
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}
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else
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{
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runsrc = rundest + ((int)window_size - match_offset);
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copy_length = match_offset - (int)window_posn;
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if(copy_length < match_length)
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{
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match_length -= copy_length;
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window_posn += (uint)copy_length;
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while(copy_length-- > 0) window[rundest++] = window[runsrc++];
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runsrc = 0;
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}
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}
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window_posn += (uint)match_length;
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// Copy match data - no worries about destination wraps
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while(match_length-- > 0) window[rundest++] = window[runsrc++];
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}
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}
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break;
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case LzxConstants.BLOCKTYPE.ALIGNED:
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while(this_run > 0)
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{
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main_element = (int)ReadHuffSym(m_state.MAINTREE_table, m_state.MAINTREE_len,
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LzxConstants.MAINTREE_MAXSYMBOLS, LzxConstants.MAINTREE_TABLEBITS,
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bitbuf);
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if(main_element < LzxConstants.NUM_CHARS)
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{
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// Literal 0 to NUM_CHARS-1
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window[window_posn++] = (byte)main_element;
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this_run -= 1;
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}
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else
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{
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// Match: NUM_CHARS + ((slot<<3) | length_header (3 bits))
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main_element -= LzxConstants.NUM_CHARS;
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match_length = main_element & LzxConstants.NUM_PRIMARY_LENGTHS;
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if(match_length == LzxConstants.NUM_PRIMARY_LENGTHS)
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{
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length_footer = (int)ReadHuffSym(m_state.LENGTH_table, m_state.LENGTH_len,
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LzxConstants.LENGTH_MAXSYMBOLS, LzxConstants.LENGTH_TABLEBITS,
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bitbuf);
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match_length += length_footer;
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}
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match_length += LzxConstants.MIN_MATCH;
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match_offset = main_element >> 3;
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if(match_offset > 2)
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{
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// Not repeated offset.
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extra = extra_bits[match_offset];
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match_offset = (int)position_base[match_offset] - 2;
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if(extra > 3)
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{
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// Verbatim and aligned bits.
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extra -= 3;
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verbatim_bits = (int)bitbuf.ReadBits((byte)extra);
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match_offset += (verbatim_bits << 3);
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aligned_bits = (int)ReadHuffSym(m_state.ALIGNED_table, m_state.ALIGNED_len,
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LzxConstants.ALIGNED_MAXSYMBOLS, LzxConstants.ALIGNED_TABLEBITS,
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bitbuf);
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match_offset += aligned_bits;
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}
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else if(extra == 3)
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{
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// Aligned bits only.
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aligned_bits = (int)ReadHuffSym(m_state.ALIGNED_table, m_state.ALIGNED_len,
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LzxConstants.ALIGNED_MAXSYMBOLS, LzxConstants.ALIGNED_TABLEBITS,
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bitbuf);
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match_offset += aligned_bits;
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}
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else if (extra > 0) // extra==1, extra==2
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{
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// Verbatim bits only.
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verbatim_bits = (int)bitbuf.ReadBits((byte)extra);
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match_offset += verbatim_bits;
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}
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else // extra == 0
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{
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// ???
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match_offset = 1;
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}
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// Update repeated offset LRU queue.
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R2 = R1; R1 = R0; R0 = (uint)match_offset;
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}
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else if( match_offset == 0)
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{
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match_offset = (int)R0;
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}
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else if(match_offset == 1)
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{
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match_offset = (int)R1;
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R1 = R0; R0 = (uint)match_offset;
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}
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else // match_offset == 2
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{
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match_offset = (int)R2;
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R2 = R0; R0 = (uint)match_offset;
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}
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rundest = (int)window_posn;
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this_run -= match_length;
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// Copy any wrapped around source data
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if(window_posn >= match_offset)
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{
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// No wrap
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runsrc = rundest - match_offset;
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}
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else
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{
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runsrc = rundest + ((int)window_size - match_offset);
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copy_length = match_offset - (int)window_posn;
|
|
|
if(copy_length < match_length)
|
|
|
{
|
|
|
match_length -= copy_length;
|
|
|
window_posn += (uint)copy_length;
|
|
|
while(copy_length-- > 0) window[rundest++] = window[runsrc++];
|
|
|
runsrc = 0;
|
|
|
}
|
|
|
}
|
|
|
window_posn += (uint)match_length;
|
|
|
|
|
|
// Copy match data - no worries about destination wraps.
|
|
|
while(match_length-- > 0) window[rundest++] = window[runsrc++];
|
|
|
}
|
|
|
}
|
|
|
break;
|
|
|
|
|
|
case LzxConstants.BLOCKTYPE.UNCOMPRESSED:
|
|
|
if((inData.Position + this_run) > endpos) return -1; // TODO: Throw proper exception
|
|
|
byte[] temp_buffer = new byte[this_run];
|
|
|
inData.Read(temp_buffer, 0, this_run);
|
|
|
temp_buffer.CopyTo(window, (int)window_posn);
|
|
|
window_posn += (uint)this_run;
|
|
|
break;
|
|
|
|
|
|
default:
|
|
|
return -1; // TODO: Throw proper exception
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
if(togo != 0) return -1; // TODO: Throw proper exception
|
|
|
int start_window_pos = (int)window_posn;
|
|
|
if(start_window_pos == 0) start_window_pos = (int)window_size;
|
|
|
start_window_pos -= outLen;
|
|
|
outData.Write(window, start_window_pos, outLen);
|
|
|
|
|
|
m_state.window_posn = window_posn;
|
|
|
m_state.R0 = R0;
|
|
|
m_state.R1 = R1;
|
|
|
m_state.R2 = R2;
|
|
|
|
|
|
// TODO: Finish intel E8 decoding.
|
|
|
// Intel E8 decoding.
|
|
|
if((m_state.frames_read++ < 32768) && m_state.intel_filesize != 0)
|
|
|
{
|
|
|
if(outLen <= 6 || m_state.intel_started == 0)
|
|
|
{
|
|
|
m_state.intel_curpos += outLen;
|
|
|
}
|
|
|
else
|
|
|
{
|
|
|
int dataend = outLen - 10;
|
|
|
uint curpos = (uint)m_state.intel_curpos;
|
|
|
|
|
|
m_state.intel_curpos = (int)curpos + outLen;
|
|
|
|
|
|
while(outData.Position < dataend)
|
|
|
{
|
|
|
if(outData.ReadByte() != 0xE8) { curpos++; continue; }
|
|
|
}
|
|
|
}
|
|
|
return -1;
|
|
|
}
|
|
|
return 0;
|
|
|
}
|
|
|
|
|
|
// TODO: Make returns throw exceptions
|
|
|
private int MakeDecodeTable(uint nsyms, uint nbits, byte[] length, ushort[] table)
|
|
|
{
|
|
|
ushort sym;
|
|
|
uint leaf;
|
|
|
byte bit_num = 1;
|
|
|
uint fill;
|
|
|
uint pos = 0; // The current position in the decode table.
|
|
|
uint table_mask = (uint)(1 << (int)nbits);
|
|
|
uint bit_mask = table_mask >> 1; // Don't do 0 length codes.
|
|
|
uint next_symbol = bit_mask; // Base of allocation for long codes.
|
|
|
|
|
|
// Fill entries for codes short enough for a direct mapping.
|
|
|
while (bit_num <= nbits )
|
|
|
{
|
|
|
for(sym = 0; sym < nsyms; sym++)
|
|
|
{
|
|
|
if(length[sym] == bit_num)
|
|
|
{
|
|
|
leaf = pos;
|
|
|
|
|
|
if ((pos += bit_mask) > table_mask)
|
|
|
{
|
|
|
return 1; // Table overrun
|
|
|
}
|
|
|
|
|
|
/* Fill all possible lookups of this symbol with the
|
|
|
* symbol itself.
|
|
|
*/
|
|
|
fill = bit_mask;
|
|
|
while(fill-- > 0) table[leaf++] = sym;
|
|
|
}
|
|
|
}
|
|
|
bit_mask >>= 1;
|
|
|
bit_num++;
|
|
|
}
|
|
|
|
|
|
// If there are any codes longer than nbits
|
|
|
if(pos != table_mask)
|
|
|
{
|
|
|
// Clear the remainder of the table.
|
|
|
for(sym = (ushort)pos; sym < table_mask; sym++) table[sym] = 0;
|
|
|
|
|
|
// Give ourselves room for codes to grow by up to 16 more bits.
|
|
|
pos <<= 16;
|
|
|
table_mask <<= 16;
|
|
|
bit_mask = 1 << 15;
|
|
|
|
|
|
while(bit_num <= 16)
|
|
|
{
|
|
|
for(sym = 0; sym < nsyms; sym++)
|
|
|
{
|
|
|
if(length[sym] == bit_num)
|
|
|
{
|
|
|
leaf = pos >> 16;
|
|
|
for(fill = 0; fill < bit_num - nbits; fill++)
|
|
|
{
|
|
|
// if this path hasn't been taken yet, 'allocate' two entries.
|
|
|
if(table[leaf] == 0)
|
|
|
{
|
|
|
table[(next_symbol << 1)] = 0;
|
|
|
table[(next_symbol << 1) + 1] = 0;
|
|
|
table[leaf] = (ushort)(next_symbol++);
|
|
|
}
|
|
|
// Follow the path and select either left or right for next bit.
|
|
|
leaf = (uint)(table[leaf] << 1);
|
|
|
if(((pos >> (int)(15-fill)) & 1) == 1) leaf++;
|
|
|
}
|
|
|
table[leaf] = sym;
|
|
|
|
|
|
if((pos += bit_mask) > table_mask) return 1;
|
|
|
}
|
|
|
}
|
|
|
bit_mask >>= 1;
|
|
|
bit_num++;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
// full table?
|
|
|
if(pos == table_mask) return 0;
|
|
|
|
|
|
// Either erroneous table, or all elements are 0 - let's find out.
|
|
|
for(sym = 0; sym < nsyms; sym++) if(length[sym] != 0) return 1;
|
|
|
return 0;
|
|
|
}
|
|
|
|
|
|
// TODO: Throw exceptions instead of returns
|
|
|
private void ReadLengths(byte[] lens, uint first, uint last, BitBuffer bitbuf)
|
|
|
{
|
|
|
uint x, y;
|
|
|
int z;
|
|
|
|
|
|
// hufftbl pointer here?
|
|
|
|
|
|
for(x = 0; x < 20; x++)
|
|
|
{
|
|
|
y = bitbuf.ReadBits(4);
|
|
|
m_state.PRETREE_len[x] = (byte)y;
|
|
|
}
|
|
|
MakeDecodeTable(LzxConstants.PRETREE_MAXSYMBOLS, LzxConstants.PRETREE_TABLEBITS,
|
|
|
m_state.PRETREE_len, m_state.PRETREE_table);
|
|
|
|
|
|
for(x = first; x < last;)
|
|
|
{
|
|
|
z = (int)ReadHuffSym(m_state.PRETREE_table, m_state.PRETREE_len,
|
|
|
LzxConstants.PRETREE_MAXSYMBOLS, LzxConstants.PRETREE_TABLEBITS, bitbuf);
|
|
|
if(z == 17)
|
|
|
{
|
|
|
y = bitbuf.ReadBits(4); y += 4;
|
|
|
while(y-- != 0) lens[x++] = 0;
|
|
|
}
|
|
|
else if(z == 18)
|
|
|
{
|
|
|
y = bitbuf.ReadBits(5); y += 20;
|
|
|
while(y-- != 0) lens[x++] = 0;
|
|
|
}
|
|
|
else if(z == 19)
|
|
|
{
|
|
|
y = bitbuf.ReadBits(1); y += 4;
|
|
|
z = (int)ReadHuffSym(m_state.PRETREE_table, m_state.PRETREE_len,
|
|
|
LzxConstants.PRETREE_MAXSYMBOLS, LzxConstants.PRETREE_TABLEBITS, bitbuf);
|
|
|
z = lens[x] - z; if(z < 0) z += 17;
|
|
|
while(y-- != 0) lens[x++] = (byte)z;
|
|
|
}
|
|
|
else
|
|
|
{
|
|
|
z = lens[x] - z; if(z < 0) z += 17;
|
|
|
lens[x++] = (byte)z;
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
private uint ReadHuffSym(ushort[] table, byte[] lengths, uint nsyms, uint nbits, BitBuffer bitbuf)
|
|
|
{
|
|
|
uint i, j;
|
|
|
bitbuf.EnsureBits(16);
|
|
|
if((i = table[bitbuf.PeekBits((byte)nbits)]) >= nsyms)
|
|
|
{
|
|
|
j = (uint)(1 << (int)((sizeof(uint)*8) - nbits));
|
|
|
do
|
|
|
{
|
|
|
j >>= 1; i <<= 1; i |= (bitbuf.GetBuffer() & j) != 0 ? (uint)1 : 0;
|
|
|
if(j == 0) return 0; // TODO: throw proper exception
|
|
|
} while((i = table[i]) >= nsyms);
|
|
|
}
|
|
|
j = lengths[i];
|
|
|
bitbuf.RemoveBits((byte)j);
|
|
|
|
|
|
return i;
|
|
|
}
|
|
|
|
|
|
#region Our BitBuffer Class
|
|
|
private class BitBuffer
|
|
|
{
|
|
|
uint buffer;
|
|
|
byte bitsleft;
|
|
|
Stream byteStream;
|
|
|
|
|
|
public BitBuffer(Stream stream)
|
|
|
{
|
|
|
byteStream = stream;
|
|
|
InitBitStream();
|
|
|
}
|
|
|
|
|
|
public void InitBitStream()
|
|
|
{
|
|
|
buffer = 0;
|
|
|
bitsleft = 0;
|
|
|
}
|
|
|
|
|
|
public void EnsureBits(byte bits)
|
|
|
{
|
|
|
while(bitsleft < bits) {
|
|
|
int lo = (byte)byteStream.ReadByte();
|
|
|
int hi = (byte)byteStream.ReadByte();
|
|
|
buffer |= (uint)(((hi << 8) | lo) << (sizeof(uint)*8 - 16 - bitsleft));
|
|
|
bitsleft += 16;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
public uint PeekBits(byte bits)
|
|
|
{
|
|
|
return (buffer >> ((sizeof(uint)*8) - bits));
|
|
|
}
|
|
|
|
|
|
public void RemoveBits(byte bits)
|
|
|
{
|
|
|
buffer <<= bits;
|
|
|
bitsleft -= bits;
|
|
|
}
|
|
|
|
|
|
public uint ReadBits(byte bits)
|
|
|
{
|
|
|
uint ret = 0;
|
|
|
|
|
|
if(bits > 0)
|
|
|
{
|
|
|
EnsureBits(bits);
|
|
|
ret = PeekBits(bits);
|
|
|
RemoveBits(bits);
|
|
|
}
|
|
|
|
|
|
return ret;
|
|
|
}
|
|
|
|
|
|
public uint GetBuffer()
|
|
|
{
|
|
|
return buffer;
|
|
|
}
|
|
|
|
|
|
public byte GetBitsLeft()
|
|
|
{
|
|
|
return bitsleft;
|
|
|
}
|
|
|
}
|
|
|
#endregion
|
|
|
|
|
|
struct LzxState {
|
|
|
public uint R0, R1, R2; // For the LRU offset system
|
|
|
public ushort main_elements; // Number of main tree elements
|
|
|
public int header_read; // Have we started decoding at all yet?
|
|
|
public LzxConstants.BLOCKTYPE block_type; // Type of this block
|
|
|
public uint block_length; // Uncompressed length of this block
|
|
|
public uint block_remaining; // Uncompressed bytes still left to decode
|
|
|
public uint frames_read; // The number of CFDATA blocks processed
|
|
|
public int intel_filesize; // Magic header value used for transform
|
|
|
public int intel_curpos; // Current offset in transform space
|
|
|
public int intel_started; // Have we seen any translateable data yet?
|
|
|
|
|
|
public ushort[] PRETREE_table;
|
|
|
public byte[] PRETREE_len;
|
|
|
public ushort[] MAINTREE_table;
|
|
|
public byte[] MAINTREE_len;
|
|
|
public ushort[] LENGTH_table;
|
|
|
public byte[] LENGTH_len;
|
|
|
public ushort[] ALIGNED_table;
|
|
|
public byte[] ALIGNED_len;
|
|
|
|
|
|
/* NEEDED MEMBERS
|
|
|
* CAB actualsize
|
|
|
* CAB window
|
|
|
* CAB window_size
|
|
|
* CAB window_posn
|
|
|
*/
|
|
|
public uint actual_size;
|
|
|
public byte[] window;
|
|
|
public uint window_size;
|
|
|
public uint window_posn;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
// CONSTANTS
|
|
|
struct LzxConstants {
|
|
|
public const ushort MIN_MATCH = 2;
|
|
|
public const ushort MAX_MATCH = 257;
|
|
|
public const ushort NUM_CHARS = 256;
|
|
|
public enum BLOCKTYPE {
|
|
|
INVALID = 0,
|
|
|
VERBATIM = 1,
|
|
|
ALIGNED = 2,
|
|
|
UNCOMPRESSED = 3
|
|
|
}
|
|
|
public const ushort PRETREE_NUM_ELEMENTS = 20;
|
|
|
public const ushort ALIGNED_NUM_ELEMENTS = 8;
|
|
|
public const ushort NUM_PRIMARY_LENGTHS = 7;
|
|
|
public const ushort NUM_SECONDARY_LENGTHS = 249;
|
|
|
|
|
|
public const ushort PRETREE_MAXSYMBOLS = PRETREE_NUM_ELEMENTS;
|
|
|
public const ushort PRETREE_TABLEBITS = 6;
|
|
|
public const ushort MAINTREE_MAXSYMBOLS = NUM_CHARS + 50*8;
|
|
|
public const ushort MAINTREE_TABLEBITS = 12;
|
|
|
public const ushort LENGTH_MAXSYMBOLS = NUM_SECONDARY_LENGTHS + 1;
|
|
|
public const ushort LENGTH_TABLEBITS = 12;
|
|
|
public const ushort ALIGNED_MAXSYMBOLS = ALIGNED_NUM_ELEMENTS;
|
|
|
public const ushort ALIGNED_TABLEBITS = 7;
|
|
|
|
|
|
public const ushort LENTABLE_SAFETY = 64;
|
|
|
}
|
|
|
|
|
|
// EXCEPTIONS
|
|
|
class UnsupportedWindowSizeRange : Exception
|
|
|
{
|
|
|
}
|
|
|
}
|
|
|
|
