/* This file is part of libmspack.
* (C) 2003-2013 Stuart Caie.
*
* The LZX method was created by Jonathan Forbes and Tomi Poutanen, adapted
* by Microsoft Corporation.
*
* libmspack is free software; you can redistribute it and/or modify it under
* the terms of the GNU Lesser General Public License (LGPL) version 2.1
*
* For further details, see the file COPYING.LIB distributed with libmspack
*/
/* Microsoft's LZX document (in cab-sdk.exe) and their implementation
* of the com.ms.util.cab Java package do not concur.
*
* In the LZX document, there is a table showing the correlation between
* window size and the number of position slots. It states that the 1MB
* window = 40 slots and the 2MB window = 42 slots. In the implementation,
* 1MB = 42 slots, 2MB = 50 slots. The actual calculation is 'find the
* first slot whose position base is equal to or more than the required
* window size'. This would explain why other tables in the document refer
* to 50 slots rather than 42.
*
* The constant NUM_PRIMARY_LENGTHS used in the decompression pseudocode
* is not defined in the specification.
*
* The LZX document does not state the uncompressed block has an
* uncompressed length field. Where does this length field come from, so
* we can know how large the block is? The implementation has it as the 24
* bits following after the 3 blocktype bits, before the alignment
* padding.
*
* The LZX document states that aligned offset blocks have their aligned
* offset huffman tree AFTER the main and length trees. The implementation
* suggests that the aligned offset tree is BEFORE the main and length
* trees.
*
* The LZX document decoding algorithm states that, in an aligned offset
* block, if an extra_bits value is 1, 2 or 3, then that number of bits
* should be read and the result added to the match offset. This is
* correct for 1 and 2, but not 3, where just a huffman symbol (using the
* aligned tree) should be read.
*
* Regarding the E8 preprocessing, the LZX document states 'No translation
* may be performed on the last 6 bytes of the input block'. This is
* correct. However, the pseudocode provided checks for the *E8 leader*
* up to the last 6 bytes. If the leader appears between -10 and -7 bytes
* from the end, this would cause the next four bytes to be modified, at
* least one of which would be in the last 6 bytes, which is not allowed
* according to the spec.
*
* The specification states that the huffman trees must always contain at
* least one element. However, many CAB files contain blocks where the
* length tree is completely empty (because there are no matches), and
* this is expected to succeed.
*
* The errors in LZX documentation appear have been corrected in the
* new documentation for the LZX DELTA format.
*
* http://msdn.microsoft.com/en-us/library/cc483133.aspx
*
* However, this is a different format, an extension of regular LZX.
* I have noticed the following differences, there may be more:
*
* The maximum window size has increased from 2MB to 32MB. This also
* increases the maximum number of position slots, etc.
*
* If the match length is 257 (the maximum possible), this signals
* a further length decoding step, that allows for matches up to
* 33024 bytes long.
*
* The format now allows for "reference data", supplied by the caller.
* If match offsets go further back than the number of bytes
* decompressed so far, that is them accessing the reference data.
*/
using System;
namespace LibMSPackSharp.Compression
{
public class LZX
{
#region LZX compression / decompression definitions
// Some constants defined by the LZX specification
public const int LZX_MIN_MATCH = 2;
public const int LZX_MAX_MATCH = 257;
public const int LZX_NUM_CHARS = 256;
public const int LZX_PRETREE_NUM_ELEMENTS = 20;
public const int LZX_ALIGNED_NUM_ELEMENTS = 8; // Aligned offset tree #elements
public const int LZX_NUM_PRIMARY_LENGTHS = 7; // This one missing from spec!
public const int LZX_NUM_SECONDARY_LENGTHS = 249; // Length tree #elements
// LZX huffman defines: tweak tablebits as desired
public const int LZX_PRETREE_MAXSYMBOLS = LZX_PRETREE_NUM_ELEMENTS;
public const int LZX_PRETREE_TABLEBITS = 6;
public const int LZX_MAINTREE_MAXSYMBOLS = LZX_NUM_CHARS + 290 * 8;
public const int LZX_MAINTREE_TABLEBITS = 12;
public const int LZX_LENGTH_MAXSYMBOLS = LZX_NUM_SECONDARY_LENGTHS + 1;
public const int LZX_LENGTH_TABLEBITS = 12;
public const int LZX_ALIGNED_MAXSYMBOLS = LZX_ALIGNED_NUM_ELEMENTS;
public const int LZX_ALIGNED_TABLEBITS = 7;
public const int LZX_LENTABLE_SAFETY = 64; // Table decoding overruns are allowed
public const int LZX_FRAME_SIZE = 32768; // The size of a frame in LZX
#endregion
#region LZX static data tables
/* LZX static data tables:
*
* LZX uses 'position slots' to represent match offsets. For every match,
* a small 'position slot' number and a small offset from that slot are
* encoded instead of one large offset.
*
* The number of slots is decided by how many are needed to encode the
* largest offset for a given window size. This is easy when the gap between
* slots is less than 128Kb, it's a linear relationship. But when extra_bits
* reaches its limit of 17 (because LZX can only ensure reading 17 bits of
* data at a time), we can only jump 128Kb at a time and have to start
* using more and more position slots as each window size doubles.
*
* position_base[] is an index to the position slot bases
*
* extra_bits[] states how many bits of offset-from-base data is needed.
*
* They are calculated as follows:
* extra_bits[i] = 0 where i < 4
* extra_bits[i] = floor(i/2)-1 where i >= 4 && i < 36
* extra_bits[i] = 17 where i >= 36
* position_base[0] = 0
* position_base[i] = position_base[i-1] + (1 << extra_bits[i-1])
*/
private static readonly uint[] position_slots = new uint[11]
{
30, 32, 34, 36, 38, 42, 50, 66, 98, 162, 290
};
private static readonly byte[] extra_bits = new byte[36]
{
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8,
9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16
};
private static readonly uint[] position_base = new uint[290]
{
0, 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96, 128, 192, 256, 384, 512,
768, 1024, 1536, 2048, 3072, 4096, 6144, 8192, 12288, 16384, 24576, 32768,
49152, 65536, 98304, 131072, 196608, 262144, 393216, 524288, 655360,
786432, 917504, 1048576, 1179648, 1310720, 1441792, 1572864, 1703936,
1835008, 1966080, 2097152, 2228224, 2359296, 2490368, 2621440, 2752512,
2883584, 3014656, 3145728, 3276800, 3407872, 3538944, 3670016, 3801088,
3932160, 4063232, 4194304, 4325376, 4456448, 4587520, 4718592, 4849664,
4980736, 5111808, 5242880, 5373952, 5505024, 5636096, 5767168, 5898240,
6029312, 6160384, 6291456, 6422528, 6553600, 6684672, 6815744, 6946816,
7077888, 7208960, 7340032, 7471104, 7602176, 7733248, 7864320, 7995392,
8126464, 8257536, 8388608, 8519680, 8650752, 8781824, 8912896, 9043968,
9175040, 9306112, 9437184, 9568256, 9699328, 9830400, 9961472, 10092544,
10223616, 10354688, 10485760, 10616832, 10747904, 10878976, 11010048,
11141120, 11272192, 11403264, 11534336, 11665408, 11796480, 11927552,
12058624, 12189696, 12320768, 12451840, 12582912, 12713984, 12845056,
12976128, 13107200, 13238272, 13369344, 13500416, 13631488, 13762560,
13893632, 14024704, 14155776, 14286848, 14417920, 14548992, 14680064,
14811136, 14942208, 15073280, 15204352, 15335424, 15466496, 15597568,
15728640, 15859712, 15990784, 16121856, 16252928, 16384000, 16515072,
16646144, 16777216, 16908288, 17039360, 17170432, 17301504, 17432576,
17563648, 17694720, 17825792, 17956864, 18087936, 18219008, 18350080,
18481152, 18612224, 18743296, 18874368, 19005440, 19136512, 19267584,
19398656, 19529728, 19660800, 19791872, 19922944, 20054016, 20185088,
20316160, 20447232, 20578304, 20709376, 20840448, 20971520, 21102592,
21233664, 21364736, 21495808, 21626880, 21757952, 21889024, 22020096,
22151168, 22282240, 22413312, 22544384, 22675456, 22806528, 22937600,
23068672, 23199744, 23330816, 23461888, 23592960, 23724032, 23855104,
23986176, 24117248, 24248320, 24379392, 24510464, 24641536, 24772608,
24903680, 25034752, 25165824, 25296896, 25427968, 25559040, 25690112,
25821184, 25952256, 26083328, 26214400, 26345472, 26476544, 26607616,
26738688, 26869760, 27000832, 27131904, 27262976, 27394048, 27525120,
27656192, 27787264, 27918336, 28049408, 28180480, 28311552, 28442624,
28573696, 28704768, 28835840, 28966912, 29097984, 29229056, 29360128,
29491200, 29622272, 29753344, 29884416, 30015488, 30146560, 30277632,
30408704, 30539776, 30670848, 30801920, 30932992, 31064064, 31195136,
31326208, 31457280, 31588352, 31719424, 31850496, 31981568, 32112640,
32243712, 32374784, 32505856, 32636928, 32768000, 32899072, 33030144,
33161216, 33292288, 33423360
};
private static void ResetState(LZXDStream lzx)
{
int i;
lzx.R0 = 1;
lzx.R1 = 1;
lzx.R2 = 1;
lzx.HeaderRead = 0;
lzx.BlockRemaining = 0;
lzx.BlockType = LZXBlockType.LZX_BLOCKTYPE_INVALID0;
// Initialise tables to 0 (because deltas will be applied to them)
for (i = 0; i < LZX_MAINTREE_MAXSYMBOLS; i++)
{
lzx.MAINTREE_len[i] = 0;
}
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS; i++)
{
lzx.LENGTH_len[i] = 0;
}
}
#endregion
///
/// Allocates and initialises LZX decompression state for decoding an LZX
/// stream.
///
/// This routine uses system.alloc() to allocate memory. If memory
/// allocation fails, or the parameters to this function are invalid,
/// null is returned.
///
///
/// an mspack_system structure used to read from
/// the input stream and write to the output
/// stream, also to allocate and free memory.
///
/// an input stream with the LZX data.
/// an output stream to write the decoded data to.
///
/// the size of the decoding window, which must be
/// between 15 and 21 inclusive for regular LZX
/// data, or between 17 and 25 inclusive for
/// LZX DELTA data.
///
/// the interval at which the LZX bitstream is
/// reset, in multiples of LZX frames (32678
/// bytes), e.g. a value of 2 indicates the input
/// stream resets after every 65536 output bytes.
/// A value of 0 indicates that the bitstream never
/// resets, such as in CAB LZX streams.
///
///
/// the number of bytes to use as an input
/// bitstream buffer.
///
///
/// the length in bytes of the entirely
/// decompressed output stream, if known in
/// advance. It is used to correctly perform the
/// Intel E8 transformation, which must stop 6
/// bytes before the very end of the
/// decompressed stream. It is not otherwise used
/// or adhered to. If the full decompressed
/// length is known in advance, set it here.
/// If it is NOT known, use the value 0, and call
/// lzxd_set_outputLength() once it is
/// known. If never set, 4 of the final 6 bytes
/// of the output stream may be incorrect.
///
///
/// should be zero for all regular LZX data,
/// non-zero for LZX DELTA encoded data.
///
///
/// a pointer to an initialised LZXDStream structure, or null if
/// there was not enough memory or parameters to the function were wrong.
///
public static LZXDStream Init(SystemImpl system, object input, object output, int windowBits, int resetInterval, int inputBufferSize, long outputLength, bool isDelta)
{
uint windowSize = (uint)(1 << windowBits);
if (system == null) return null;
// LZX DELTA window sizes are between 2^17 (128KiB) and 2^25 (32MiB),
// regular LZX windows are between 2^15 (32KiB) and 2^21 (2MiB)
if (isDelta)
{
if (windowBits < 17 || windowBits > 25)
return null;
}
else
{
if (windowBits < 15 || windowBits > 21)
return null;
}
if (resetInterval < 0 || outputLength < 0)
{
Console.WriteLine("reset interval or output length < 0");
return null;
}
// Round up input buffer size to multiple of two
inputBufferSize = (inputBufferSize + 1) & -2;
if (inputBufferSize < 2)
return null;
// Allocate decompression state
LZXDStream lzx = new LZXDStream();
// Allocate decompression window and input buffer
lzx.Window = new byte[windowSize];
lzx.InputBuffer = new byte[inputBufferSize];
// Initialise decompression state
lzx.Sys = system;
lzx.Input = input;
lzx.Output = output;
lzx.Offset = 0;
lzx.Length = outputLength;
lzx.InputBufferSize = (uint)inputBufferSize;
lzx.WindowSize = (uint)(1 << windowBits);
lzx.ReferenceDataSize = 0;
lzx.WindowPosition = 0;
lzx.FramePosition = 0;
lzx.Frame = 0;
lzx.ResetInterval = (uint)resetInterval;
lzx.IntelFileSize = 0;
lzx.IntelStarted = false;
lzx.Error = Error.MSPACK_ERR_OK;
lzx.NumOffsets = position_slots[windowBits - 15] << 3;
lzx.IsDelta = isDelta;
lzx.OutputPointer = lzx.OutputLength = 0;
ResetState(lzx);
lzx.INIT_BITS();
return lzx;
}
// See description of outputLength in lzxd_init()
public static void SetOutputLength(LZXDStream lzx, long outputLength)
{
if (lzx != null && outputLength > 0)
lzx.Length = outputLength;
}
///
/// Reads LZX DELTA reference data into the window and allows
/// lzxd_decompress() to reference it.
///
/// Call this before the first call to lzxd_decompress().
///
/// the LZX stream to apply this reference data to
///
/// an mspack_system implementation to use with the
/// input param. Only read() will be called.
///
/// an input file handle to read reference data using system.read().
///
/// the length of the reference data. Cannot be longer
/// than the LZX window size.
///
/// an error code, or MSPACK_ERR_OK if successful
public static Error SetReferenceData(LZXDStream lzx, SystemImpl system, object input, uint length)
{
if (lzx == null)
return Error.MSPACK_ERR_ARGS;
if (!lzx.IsDelta)
{
Console.WriteLine("only LZX DELTA streams support reference data");
return Error.MSPACK_ERR_ARGS;
}
if (lzx.Offset != 0)
{
Console.WriteLine("too late to set reference data after decoding starts");
return Error.MSPACK_ERR_ARGS;
}
if (length > lzx.WindowSize)
{
Console.WriteLine($"reference length ({length}) is longer than the window");
return Error.MSPACK_ERR_ARGS;
}
if (length > 0 && (system == null || input == null))
{
Console.WriteLine("length > 0 but no system or input");
return Error.MSPACK_ERR_ARGS;
}
lzx.ReferenceDataSize = length;
if (length > 0)
{
// Copy reference data
int pos = (int)(lzx.WindowSize - length);
int bytes = system.Read(input, lzx.Window, pos, (int)length);
// length can't be more than 2^25, so no signedness problem
if (bytes < (int)length)
return Error.MSPACK_ERR_READ;
}
lzx.ReferenceDataSize = length;
return Error.MSPACK_ERR_OK;
}
///
/// Decompresses entire or partial LZX streams.
///
/// The number of bytes of data that should be decompressed is given as the
/// out_bytes parameter. If more bytes are decoded than are needed, they
/// will be kept over for a later invocation.
///
/// The output bytes will be passed to the system.write() function given in
/// lzxd_init(), using the output file handle given in lzxd_init(). More than
/// one call may be made to system.write().
/// Input bytes will be read in as necessary using the system.read()
/// function given in lzxd_init(), using the input file handle given in
/// lzxd_init(). This will continue until system.read() returns 0 bytes,
/// or an error. Errors will be passed out of the function as
/// MSPACK_ERR_READ errors. Input streams should convey an "end of input
/// stream" by refusing to supply all the bytes that LZX asks for when they
/// reach the end of the stream, rather than return an error code.
///
/// If any error code other than MSPACK_ERR_OK is returned, the stream
/// should be considered unusable and lzxd_decompress() should not be
/// called again on this stream.
///
/// LZX decompression state, as allocated by lzxd_init().
/// the number of bytes of data to decompress.
/// an error code, or MSPACK_ERR_OK if successful
public static Error Decompress(object o, long outBytes)
{
LZXDStream lzx = o as LZXDStream;
if (lzx == null)
return Error.MSPACK_ERR_ARGS;
// Bitstream and huffman reading variables
uint bit_buffer = 0, bits_left = 0;
int i_ptr = 0, i_end = 0;
ushort sym = 0;
int match_length, extra, verbatim_bits = 0, bytes_todo;
int this_run, j = 0, warned = 0;
uint main_element = 0, length_footer = 0, aligned_bits = 0;
byte[] window, buf = new byte[12];
int runsrc, rundest;
uint frame_size = 0, end_frame, match_offset, window_posn;
uint R0, R1, R2;
// Easy answers
if (lzx == null || (outBytes < 0))
return Error.MSPACK_ERR_ARGS;
if (lzx.Error != Error.MSPACK_ERR_OK)
return lzx.Error;
// Flush out any stored-up bytes before we begin
int i = lzx.OutputLength - lzx.OutputPointer;
if (i > outBytes)
i = (int)outBytes;
if (i != 0)
{
if (lzx.Sys.Write(lzx.Output, lzx.e8_buf, lzx.OutputPointer, i) != i)
return lzx.Error = Error.MSPACK_ERR_WRITE;
lzx.OutputPointer += i;
lzx.Offset += i;
outBytes -= i;
}
if (outBytes == 0) return Error.MSPACK_ERR_OK;
// Restore local state
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
window = lzx.Window;
window_posn = lzx.WindowPosition;
R0 = lzx.R0;
R1 = lzx.R1;
R2 = lzx.R2;
end_frame = (uint)((lzx.Offset + outBytes) / LZX_FRAME_SIZE) + 1;
while (lzx.Frame < end_frame)
{
// Have we reached the reset interval? (if there is one?)
if (lzx.ResetInterval != 0 && ((lzx.Frame % lzx.ResetInterval) == 0))
{
if (lzx.BlockRemaining != 0)
{
// This is a file format error, we can make a best effort to extract what we can
Console.WriteLine("%d bytes remaining at reset interval", lzx.BlockRemaining);
if (warned == 0)
{
lzx.Sys.Message(null, "WARNING; invalid reset interval detected during LZX decompression");
warned++;
}
}
// Re-read the intel header and reset the huffman lengths
ResetState(lzx);
R0 = lzx.R0;
R1 = lzx.R1;
R2 = lzx.R2;
}
// LZX DELTA format has chunk_size, not present in LZX format
if (lzx.IsDelta)
{
lzx.ENSURE_BITS(16, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
lzx.REMOVE_BITS(16, ref bits_left, ref bit_buffer);
}
// Read header if necessary
if (lzx.HeaderRead == 0)
{
/* read 1 bit. if bit=0, intel filesize = 0.
* if bit=1, read intel filesize (32 bits) */
j = 0;
lzx.READ_BITS(ref i, 1, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
if (i != 0)
{
lzx.READ_BITS(ref i, 16, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
lzx.READ_BITS(ref j, 16, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
}
lzx.IntelFileSize = (i << 16) | j;
lzx.HeaderRead = 1;
}
// Calculate size of frame: all frames are 32k except the final frame
// which is 32kb or less. this can only be calculated when lzx.Length
// has been filled in.
frame_size = LZX_FRAME_SIZE;
if (lzx.Length != 0 && (lzx.Length - lzx.Offset) < frame_size)
frame_size = (uint)(lzx.Length - lzx.Offset);
// Decode until one more frame is available
bytes_todo = (int)(lzx.FramePosition + frame_size - window_posn);
while (bytes_todo > 0)
{
// Initialise new block, if one is needed
if (lzx.BlockRemaining == 0)
{
// Realign if previous block was an odd-sized UNCOMPRESSED block
if ((lzx.BlockType == LZXBlockType.LZX_BLOCKTYPE_UNCOMPRESSED) && (lzx.BlockLength & 1) != 0)
{
lzx.READ_IF_NEEDED(ref i_ptr, ref i_end);
if (lzx.Error != Error.MSPACK_ERR_OK)
return lzx.Error;
i_ptr++;
}
// Read block type (3 bits) and block length (24 bits)
int blockType = 0;
lzx.READ_BITS(ref blockType, 3, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
lzx.BlockType = (LZXBlockType)blockType;
lzx.READ_BITS(ref i, 16, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
lzx.READ_BITS(ref j, 8, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
lzx.BlockRemaining = lzx.BlockLength = (uint)((i << 8) | j);
// Console.WriteLine("new block t%d len %u", lzx.BlockType, lzx.BlockLength);
// Read individual block headers
switch (lzx.BlockType)
{
// Read lengths of and build aligned huffman decoding tree
case LZXBlockType.LZX_BLOCKTYPE_ALIGNED:
for (i = 0; i < 8; i++)
{
lzx.READ_BITS(ref j, 3, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
lzx.ALIGNED_len[i] = (byte)j;
}
//BUILD_TABLE(ALIGNED)
if (LZXDStream.MakeDecodeTable(LZX_ALIGNED_MAXSYMBOLS, LZX_ALIGNED_TABLEBITS, lzx.ALIGNED_len, lzx.ALIGNED_table) != 0)
{
Console.WriteLine("failed to build ALIGNED table");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// Read lengths of and build main huffman decoding tree
//READ_LENGTHS(tbl, first, last)
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
if (ReadLens(lzx, lzx.MAINTREE_len, 0, 256) != 0)
return lzx.Error;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
//READ_LENGTHS(tbl, first, last)
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
if (ReadLens(lzx, lzx.MAINTREE_len, 256, LZX_NUM_CHARS + lzx.NumOffsets) != 0)
return lzx.Error;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
//BUILD_TABLE(MAINTREE)
if (LZXDStream.MakeDecodeTable(LZX_MAINTREE_MAXSYMBOLS, LZX_MAINTREE_TABLEBITS, lzx.MAINTREE_len, lzx.MAINTREE_table) != 0)
{
Console.WriteLine("failed to build MAINTREE table");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// If the literal 0xE8 is anywhere in the block...
if (lzx.MAINTREE_len[0xE8] != 0)
lzx.IntelStarted = true;
// Read lengths of and build lengths huffman decoding tree
//READ_LENGTHS(tbl, first, last)
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
if (ReadLens(lzx, lzx.LENGTH_len, 0, LZX_NUM_SECONDARY_LENGTHS) != 0)
return lzx.Error;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
//BUILD_TABLE_MAYBE_EMPTY(LENGTH)
lzx.LENGTH_empty = 0;
if (LZXDStream.MakeDecodeTable(LZX_LENGTH_MAXSYMBOLS, LZX_LENGTH_TABLEBITS, lzx.LENGTH_len, lzx.LENGTH_table) != 0)
{
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS; i++)
{
if (lzx.LENGTH_len[i] > 0)
{
Console.WriteLine("failed to build LENGTH table");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
}
// Empty tree - allow it, but don't decode symbols with it
lzx.LENGTH_empty = 1;
}
break;
case LZXBlockType.LZX_BLOCKTYPE_VERBATIM:
// Read lengths of and build main huffman decoding tree
//READ_LENGTHS(tbl, first, last)
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
if (ReadLens(lzx, lzx.MAINTREE_len, 0, 256) != 0)
return lzx.Error;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
//READ_LENGTHS(tbl, first, last)
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
if (ReadLens(lzx, lzx.MAINTREE_len, 256, LZX_NUM_CHARS + lzx.NumOffsets) != 0)
return lzx.Error;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
//BUILD_TABLE(MAINTREE)
if (LZXDStream.MakeDecodeTable(LZX_MAINTREE_MAXSYMBOLS, LZX_MAINTREE_TABLEBITS, lzx.MAINTREE_len, lzx.MAINTREE_table) != 0)
{
Console.WriteLine("failed to build MAINTREE table");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// If the literal 0xE8 is anywhere in the block...
if (lzx.MAINTREE_len[0xE8] != 0)
lzx.IntelStarted = true;
// Read lengths of and build lengths huffman decoding tree
//READ_LENGTHS(tbl, first, last)
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
if (ReadLens(lzx, lzx.LENGTH_len, 0, LZX_NUM_SECONDARY_LENGTHS) != 0)
return lzx.Error;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
//BUILD_TABLE_MAYBE_EMPTY(LENGTH)
lzx.LENGTH_empty = 0;
if (LZXDStream.MakeDecodeTable(LZX_LENGTH_MAXSYMBOLS, LZX_LENGTH_TABLEBITS, lzx.LENGTH_len, lzx.LENGTH_table) != 0)
{
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS; i++)
{
if (lzx.LENGTH_len[i] > 0)
{
Console.WriteLine("failed to build LENGTH table");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
}
// Empty tree - allow it, but don't decode symbols with it
lzx.LENGTH_empty = 1;
}
break;
case LZXBlockType.LZX_BLOCKTYPE_UNCOMPRESSED:
// Because we can't assume otherwise
lzx.IntelStarted = true;
// Read 1-16 (not 0-15) bits to align to bytes
if (bits_left == 0)
lzx.ENSURE_BITS(16, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
bits_left = 0; bit_buffer = 0;
// Read 12 bytes of stored R0 / R1 / R2 values
for (rundest = 0, i = 0; i < 12; i++)
{
lzx.READ_IF_NEEDED(ref i_ptr, ref i_end);
if (lzx.Error != Error.MSPACK_ERR_OK)
return lzx.Error;
buf[rundest++] = lzx.InputBuffer[i_ptr++];
}
R0 = (uint)(buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24));
R1 = (uint)(buf[4] | (buf[5] << 8) | (buf[6] << 16) | (buf[7] << 24));
R2 = (uint)(buf[8] | (buf[9] << 8) | (buf[10] << 16) | (buf[11] << 24));
break;
default:
Console.WriteLine("bad block type");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
}
// decode more of the block:
// run = min(what's available, what's needed)
this_run = (int)lzx.BlockRemaining;
if (this_run > bytes_todo)
this_run = bytes_todo;
// Assume we decode exactly this_run bytes, for now
bytes_todo -= this_run;
lzx.BlockRemaining -= (uint)this_run;
// Decode at least this_run bytes
switch (lzx.BlockType)
{
case LZXBlockType.LZX_BLOCKTYPE_ALIGNED:
case LZXBlockType.LZX_BLOCKTYPE_VERBATIM:
while (this_run > 0)
{
lzx.READ_HUFFSYM(lzx.MAINTREE_table, ref main_element, LZX_MAINTREE_TABLEBITS, lzx.MAINTREE_len, LZX_MAINTREE_MAXSYMBOLS, ref i, ref sym, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
if (main_element < LZX_NUM_CHARS)
{
// Literal: 0 to LZX_NUM_CHARS-1
window[window_posn++] = (byte)main_element;
this_run--;
}
else
{
// Match: LZX_NUM_CHARS + ((slot<<3) | length_header (3 bits))
main_element -= LZX_NUM_CHARS;
// Get match length
match_length = (int)(main_element & LZX_NUM_PRIMARY_LENGTHS);
if (match_length == LZX_NUM_PRIMARY_LENGTHS)
{
if (lzx.LENGTH_empty != 0)
{
Console.WriteLine("LENGTH symbol needed but tree is empty");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
lzx.READ_HUFFSYM(lzx.LENGTH_table, ref length_footer, LZX_LENGTH_TABLEBITS, lzx.LENGTH_len, LZX_LENGTH_MAXSYMBOLS, ref i, ref sym, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
match_length += (int)length_footer;
}
match_length += LZX_MIN_MATCH;
// Get match offset
switch ((match_offset = (uint)(main_element >> 3)))
{
case 0: match_offset = R0; break;
case 1: match_offset = R1; R1 = R0; R0 = match_offset; break;
case 2: match_offset = R2; R2 = R0; R0 = match_offset; break;
default:
if (lzx.BlockType == LZXBlockType.LZX_BLOCKTYPE_VERBATIM)
{
if (match_offset == 3)
{
match_offset = 1;
}
else
{
extra = (match_offset >= 36) ? 17 : extra_bits[match_offset];
lzx.READ_BITS(ref verbatim_bits, extra, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
match_offset = (uint)(position_base[match_offset] - 2 + verbatim_bits);
}
}
// LZX_BLOCKTYPE_ALIGNED
else
{
extra = (match_offset >= 36) ? 17 : extra_bits[match_offset];
match_offset = position_base[match_offset] - 2;
if (extra > 3)
{
// >3: verbatim and aligned bits
extra -= 3;
lzx.READ_BITS(ref verbatim_bits, extra, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
match_offset += (uint)(verbatim_bits << 3);
lzx.READ_HUFFSYM(lzx.ALIGNED_table, ref aligned_bits, LZX_ALIGNED_TABLEBITS, lzx.ALIGNED_len, LZX_ALIGNED_MAXSYMBOLS, ref i, ref sym, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
match_offset += aligned_bits;
}
else if (extra == 3)
{
// 3: aligned bits only
lzx.READ_HUFFSYM(lzx.ALIGNED_table, ref aligned_bits, LZX_ALIGNED_TABLEBITS, lzx.ALIGNED_len, LZX_ALIGNED_MAXSYMBOLS, ref i, ref sym, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
match_offset += aligned_bits;
}
else if (extra > 0)
{
// 1-2: verbatim bits only
lzx.READ_BITS(ref verbatim_bits, extra, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
match_offset += (uint)verbatim_bits;
}
else
{
// 0: not defined in LZX specification!
match_offset = 1;
}
}
// Update repeated offset LRU queue
R2 = R1; R1 = R0; R0 = match_offset;
break;
}
// LZX DELTA uses max match length to signal even longer match
if (match_length == LZX_MAX_MATCH && lzx.IsDelta)
{
int extra_len = 0;
lzx.ENSURE_BITS(3, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer); /* 4 entry huffman tree */
if (lzx.PEEK_BITS(1, bit_buffer) == 0)
{
lzx.REMOVE_BITS(1, ref bits_left, ref bit_buffer); /* '0' . 8 extra length bits */
lzx.READ_BITS(ref extra_len, 8, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
}
else if (lzx.PEEK_BITS(2, bit_buffer) == 2)
{
lzx.REMOVE_BITS(2, ref bits_left, ref bit_buffer); /* '10' . 10 extra length bits + 0x100 */
lzx.READ_BITS(ref extra_len, 10, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
extra_len += 0x100;
}
else if (lzx.PEEK_BITS(3, bit_buffer) == 6)
{
lzx.REMOVE_BITS(3, ref bits_left, ref bit_buffer); /* '110' . 12 extra length bits + 0x500 */
lzx.READ_BITS(ref extra_len, 12, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
extra_len += 0x500;
}
else
{
lzx.REMOVE_BITS(3, ref bits_left, ref bit_buffer); /* '111' . 15 extra length bits */
lzx.READ_BITS(ref extra_len, 15, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
}
match_length += extra_len;
}
if ((window_posn + match_length) > lzx.WindowSize)
{
Console.WriteLine("match ran over window wrap");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// Copy match
rundest = (int)window_posn;
i = match_length;
// Does match offset wrap the window?
if (match_offset > window_posn)
{
if (match_offset > lzx.Offset &&
(match_offset - window_posn) > lzx.ReferenceDataSize)
{
Console.WriteLine("match offset beyond LZX stream");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
/* j = length from match offset to end of window */
j = (int)(match_offset - window_posn);
if (j > (int)lzx.WindowSize)
{
Console.WriteLine("match offset beyond window boundaries");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
runsrc = (int)(lzx.WindowSize - j);
if (j < i)
{
// if match goes over the window edge, do two copy runs
i -= j;
while (j-- > 0)
{
window[rundest++] = window[runsrc++];
}
runsrc = 0;
}
while (i-- > 0)
{
window[rundest++] = window[runsrc++];
}
}
else
{
runsrc = (int)(rundest - match_offset);
while (i-- > 0)
{
window[rundest++] = window[runsrc++];
}
}
this_run -= match_length;
window_posn += (uint)match_length;
}
}
break;
case LZXBlockType.LZX_BLOCKTYPE_UNCOMPRESSED:
// As this_run is limited not to wrap a frame, this also means it
// won't wrap the window (as the window is a multiple of 32k)
rundest = (int)window_posn;
window_posn += (uint)this_run;
while (this_run > 0)
{
if ((i = i_end - i_ptr) == 0)
{
lzx.READ_IF_NEEDED(ref i_ptr, ref i_end);
if (lzx.Error != Error.MSPACK_ERR_OK)
return lzx.Error;
}
else
{
if (i > this_run)
i = this_run;
lzx.Sys.Copy(lzx.InputBuffer, i_ptr, window, rundest, i);
rundest += i;
i_ptr += i;
this_run -= i;
}
}
break;
default:
return lzx.Error = Error.MSPACK_ERR_DECRUNCH; // Might as well
}
// Did the final match overrun our desired this_run length?
if (this_run < 0)
{
if ((uint)(-this_run) > lzx.BlockRemaining)
{
Console.WriteLine($"overrun went past end of block by {-this_run} ({lzx.BlockRemaining} remaining)");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
lzx.BlockRemaining -= (uint)-this_run;
}
}
// Streams don't extend over frame boundaries
if ((window_posn - lzx.FramePosition) != frame_size)
{
Console.WriteLine("decode beyond output frame limits! %d != %d", window_posn - lzx.FramePosition, frame_size);
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// Re-align input bitstream
if (bits_left > 0)
lzx.ENSURE_BITS(16, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
if ((bits_left & 15) != 0)
lzx.REMOVE_BITS((int)(bits_left & 15), ref bits_left, ref bit_buffer);
// Check that we've used all of the previous frame first
if (lzx.OutputPointer != lzx.OutputLength)
{
Console.WriteLine($"{lzx.OutputLength - lzx.OutputPointer} avail bytes, new {frame_size} frame");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// Does this intel block _really_ need decoding?
if (lzx.IntelStarted && lzx.IntelFileSize != 0 && (lzx.Frame < 32768) && (frame_size > 10))
{
int data = 0;
int dataend = (int)(frame_size - 10);
int curpos = (int)lzx.Offset;
int filesize = lzx.IntelFileSize;
int abs_off, rel_off;
lzx.OutputPointer = data;
lzx.Sys.Copy(lzx.Window, (int)lzx.FramePosition, lzx.e8_buf, data, (int)frame_size);
while (data < dataend)
{
if (lzx.e8_buf[data++] != 0xE8)
{
curpos++;
continue;
}
abs_off = lzx.e8_buf[data + 0] | (lzx.e8_buf[data + 1] << 8) | (lzx.e8_buf[data + 2] << 16) | (lzx.e8_buf[data + 3] << 24);
if ((abs_off >= -curpos) && (abs_off < filesize))
{
rel_off = (abs_off >= 0) ? abs_off - curpos : abs_off + filesize;
lzx.e8_buf[data + 0] = (byte)rel_off;
lzx.e8_buf[data + 1] = (byte)(rel_off >> 8);
lzx.e8_buf[data + 2] = (byte)(rel_off >> 16);
lzx.e8_buf[data + 3] = (byte)(rel_off >> 24);
}
data += 4;
curpos += 5;
}
}
else
{
lzx.OutputPointer = (int)lzx.FramePosition;
}
lzx.OutputLength = (int)(lzx.OutputPointer + frame_size);
// Write a frame
i = (int)((outBytes < frame_size) ? outBytes : frame_size);
if (lzx.Sys.Write(lzx.Output, lzx.Window, lzx.OutputPointer, i) != i)
return lzx.Error = Error.MSPACK_ERR_WRITE;
lzx.OutputPointer += i;
lzx.Offset += i;
outBytes -= i;
// Advance frame start position
lzx.FramePosition += frame_size;
lzx.Frame++;
// Wrap window / frame position pointers
if (window_posn == lzx.WindowSize)
window_posn = 0;
if (lzx.FramePosition == lzx.WindowSize)
lzx.FramePosition = 0;
}
if (outBytes != 0)
{
Console.WriteLine("bytes left to output");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
// Store local state
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
lzx.WindowPosition = window_posn;
lzx.R0 = R0;
lzx.R1 = R1;
lzx.R2 = R2;
return Error.MSPACK_ERR_OK;
}
///
/// Frees all state associated with an LZX data stream. This will call
/// system.free() using the system pointer given in lzxd_init().
///
/// LZX decompression state to free.
public static void Free(object s)
{
LZXDStream lzx = s as LZXDStream;
if (lzx != null)
{
SystemImpl sys = lzx.Sys;
sys.Free(lzx.InputBuffer);
sys.Free(lzx.Window);
sys.Free(lzx);
}
}
private static Error ReadLens(LZXDStream lzx, byte[] lens, uint first, uint last)
{
// Bit buffer and huffman symbol decode variables
uint bit_buffer = 0, bits_left = 0;
int i = 0;
ushort sym = 0;
int i_ptr = 0, i_end = 0;
int x, y = 0;
uint z = 0;
lzx.RESTORE_BITS(ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
// Read lengths for pretree (20 symbols, lengths stored in fixed 4 bits)
for (x = 0; x < 20; x++)
{
lzx.READ_BITS(ref y, 4, ref i_ptr, ref i_end, ref bit_buffer, ref bits_left);
lzx.PRETREE_len[x] = (byte)y;
}
//BUILD_TABLE(PRETREE)
if (LZXDStream.MakeDecodeTable(LZX_PRETREE_MAXSYMBOLS, LZX_PRETREE_TABLEBITS, lzx.PRETREE_len, lzx.PRETREE_table) != 0)
{
Console.WriteLine("failed to build PRETREE table");
return lzx.Error = Error.MSPACK_ERR_DECRUNCH;
}
for (x = (int)first; x < last;)
{
lzx.READ_HUFFSYM(lzx.PRETREE_table, ref z, LZX_PRETREE_TABLEBITS, lzx.PRETREE_len, LZX_PRETREE_MAXSYMBOLS, ref i, ref sym, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
if (z == 17)
{
// Code = 17, run of ([read 4 bits]+4) zeros
lzx.READ_BITS(ref y, 4, ref i_ptr, ref i_end, ref bit_buffer, ref bits_left); y += 4;
while (y-- != 0)
{
lens[x++] = 0;
}
}
else if (z == 18)
{
// Code = 18, run of ([read 5 bits]+20) zeros
lzx.READ_BITS(ref y, 5, ref i_ptr, ref i_end, ref bit_buffer, ref bits_left); y += 20;
while (y-- != 0)
{
lens[x++] = 0;
}
}
else if (z == 19)
{
// Code = 19, run of ([read 1 bit]+4) [read huffman symbol]
lzx.READ_BITS(ref y, 1, ref i_ptr, ref i_end, ref bit_buffer, ref bits_left); y += 4;
lzx.READ_HUFFSYM(lzx.PRETREE_table, ref z, LZX_PRETREE_TABLEBITS, lzx.PRETREE_len, LZX_PRETREE_MAXSYMBOLS, ref i, ref sym, ref i_ptr, ref i_end, ref bits_left, ref bit_buffer);
z = lens[x] - z;
if (z < 0)
z += 17;
while (y-- != 0)
{
lens[x++] = (byte)z;
}
}
else
{
// Code = 0 to 16, delta current length entry
z = lens[x] - z;
if (z < 0)
z += 17;
lens[x++] = (byte)z;
}
}
lzx.STORE_BITS(i_ptr, i_end, bit_buffer, bits_left);
return Error.MSPACK_ERR_OK;
}
}
}