dsdecmp/CSharp/DSDecmp/Formats/LZOvl.cs

667 lines
30 KiB
C#

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using DSDecmp.Utils;
namespace DSDecmp.Formats
{
/// <summary>
/// The LZ-Overlay compression format. Compresses part of the file from end to start.
/// Is used for the 'overlay' files in NDS games, as well as arm9.bin.
/// Note that the last 12 bytes should not be included in the 'inLength' argument when
/// decompressing arm9.bin. This is done automatically if a file is given instead of a stream.
/// </summary>
public class LZOvl : CompressionFormat
{
private static bool lookAhead = false;
/// <summary>
/// Sets the flag that determines if 'look-ahead'/DP should be used when compressing
/// with the LZ-Ovl format. The default is false, which is what is used in the original
/// implementation.
/// </summary>
public static bool LookAhead
{
set { lookAhead = value; }
}
#region Method: Supports(string file)
public override bool Supports(string file)
{
using (FileStream fstr = File.OpenRead(file))
{
long fLength = fstr.Length;
// arm9.bin is special in the sense that the last 12 bytes should/can be ignored.
if (Path.GetFileName(file) == "arm9.bin")
fLength -= 0xC;
return this.Supports(fstr, fLength);
}
}
#endregion
#region Method: Supports(Stream, long)
public override bool Supports(System.IO.Stream stream, long inLength)
{
// assume the 'inLength' does not include the 12 bytes at the end of arm9.bin
// only allow integer-sized files
if (inLength > 0xFFFFFFFFL)
return false;
// the header is 4 bytes minimum
if (inLength < 4)
return false;
long streamStart = stream.Position;
byte[] header = new byte[Math.Min(inLength, 0x20)];
stream.Position += inLength - header.Length;
stream.Read(header, 0, header.Length);
// reset the stream
stream.Position = streamStart;
uint extraSize = IOUtils.ToNDSu32(header, header.Length - 4);
if (extraSize == 0)
return false; // do not decompress whenevr the last 4 bytes are 0; too many files have that.
// if the extrasize is nonzero, the minimum header length is 8 bytes
if (header.Length < 8)
return false;
byte headerLen = header[header.Length - 5];
if (inLength < headerLen)
return false;
// the compressed length should fit in the input file
int compressedLen = header[header.Length - 6] << 16
| header[header.Length - 7] << 8
| header[header.Length - 8];
if (compressedLen >= inLength - headerLen)
return false;
// verify that the rest of the header is filled with 0xFF
for (int i = header.Length - 9; i >= header.Length - headerLen; i--)
if (header[i] != 0xFF)
return false;
return true;
}
#endregion
#region Method: Decompress(string, string)
public override void Decompress(string infile, string outfile)
{
// make sure the output directory exists
string outDirectory = Path.GetDirectoryName(outfile);
if (!Directory.Exists(outDirectory))
Directory.CreateDirectory(outDirectory);
// open the two given files, and delegate to the format-specific code.
using (FileStream inStream = new FileStream(infile, FileMode.Open),
outStream = new FileStream(outfile, FileMode.Create))
{
long fLength = inStream.Length;
// arm9.bin needs special attention
if (Path.GetFileName(infile) == "arm9.bin")
fLength -= 0xC;
this.Decompress(inStream, fLength, outStream);
}
}
#endregion
#region Decompression method
public override long Decompress(System.IO.Stream instream, long inLength, System.IO.Stream outstream)
{
#region Format description
// Overlay LZ compression is basically just LZ-0x10 compression.
// however the order if reading is reversed: the compression starts at the end of the file.
// Assuming we start reading at the end towards the beginning, the format is:
/*
* u32 extraSize; // decompressed data size = file length (including header) + this value
* u8 headerSize;
* u24 compressedLength; // can be less than file size (w/o header). If so, the rest of the file is uncompressed.
* u8[headerSize-8] padding; // 0xFF-s
*
* 0x10-like-compressed data follows (without the usual 4-byte header).
* The only difference is that 2 should be added to the DISP value in compressed blocks
* to get the proper value.
* the u32 and u24 are read most significant byte first.
* if extraSize is 0, there is no headerSize, decompressedLength or padding.
* the data starts immediately, and is uncompressed.
*
* arm9.bin has 3 extra u32 values at the 'start' (ie: end of the file),
* which may be ignored. (and are ignored here) These 12 bytes also should not
* be included in the computation of the output size.
*/
#endregion
#region First read the last 4 bytes of the stream (the 'extraSize')
// first go to the end of the stream, since we're reading from back to front
// read the last 4 bytes, the 'extraSize'
instream.Position += inLength - 4;
byte[] buffer = new byte[4];
try
{
instream.Read(buffer, 0, 4);
}
catch (System.IO.EndOfStreamException)
{
// since we're immediately checking the end of the stream,
// this is the only location where we have to check for an EOS to occur.
throw new StreamTooShortException();
}
uint extraSize = IOUtils.ToNDSu32(buffer, 0);
#endregion
// if the extra size is 0, there is no compressed part, and the header ends there.
if (extraSize == 0)
{
#region just copy the input to the output
// first go back to the start of the file. the current location is after the 'extraSize',
// and thus at the end of the file.
instream.Position -= inLength;
// no buffering -> slow
buffer = new byte[inLength - 4];
instream.Read(buffer, 0, (int)(inLength - 4));
outstream.Write(buffer, 0, (int)(inLength - 4));
// make sure the input is positioned at the end of the file
instream.Position += 4;
return inLength - 4;
#endregion
}
else
{
// get the size of the compression header first.
instream.Position -= 5;
int headerSize = instream.ReadByte();
// then the compressed data size.
instream.Position -= 4;
instream.Read(buffer, 0, 3);
int compressedSize = buffer[0] | (buffer[1] << 8) | (buffer[2] << 16);
#region copy the non-compressed data
// copy the non-compressed data first.
buffer = new byte[inLength - headerSize - compressedSize];
instream.Position -= (inLength - 5);
instream.Read(buffer, 0, buffer.Length);
outstream.Write(buffer, 0, buffer.Length);
#endregion
// buffer the compressed data, such that we don't need to keep
// moving the input stream position back and forth
buffer = new byte[compressedSize];
instream.Read(buffer, 0, compressedSize);
// we're filling the output from end to start, so we can't directly write the data.
// buffer it instead (also use this data as buffer instead of a ring-buffer for
// decompression)
byte[] outbuffer = new byte[compressedSize + headerSize + extraSize];
int currentOutSize = 0;
int decompressedLength = outbuffer.Length;
int readBytes = 0;
byte flags = 0, mask = 1;
while (currentOutSize < decompressedLength)
{
// (throws when requested new flags byte is not available)
#region Update the mask. If all flag bits have been read, get a new set.
// the current mask is the mask used in the previous run. So if it masks the
// last flag bit, get a new flags byte.
if (mask == 1)
{
if (readBytes >= compressedSize)
throw new NotEnoughDataException(currentOutSize, decompressedLength);
flags = buffer[buffer.Length - 1 - readBytes]; readBytes++;
mask = 0x80;
}
else
{
mask >>= 1;
}
#endregion
// bit = 1 <=> compressed.
if ((flags & mask) > 0)
{
// (throws when < 2 bytes are available)
#region Get length and displacement('disp') values from next 2 bytes
// there are < 2 bytes available when the end is at most 1 byte away
if (readBytes + 1 >= inLength)
{
throw new NotEnoughDataException(currentOutSize, decompressedLength);
}
int byte1 = buffer[compressedSize - 1 - readBytes]; readBytes++;
int byte2 = buffer[compressedSize - 1 - readBytes]; readBytes++;
// the number of bytes to copy
int length = byte1 >> 4;
length += 3;
// from where the bytes should be copied (relatively)
int disp = ((byte1 & 0x0F) << 8) | byte2;
disp += 3;
if (disp > currentOutSize)
{
if (currentOutSize < 2)
throw new InvalidDataException("Cannot go back more than already written; "
+ "attempt to go back 0x" + disp.ToString("X") + " when only 0x"
+ currentOutSize.ToString("X") + " bytes have been written.");
// HACK. this seems to produce valid files, but isn't the most elegant solution.
// although this _could_ be the actual way to use a disp of 2 in this format,
// as otherwise the minimum would be 3 (and 0 is undefined, and 1 is less useful).
disp = 2;
}
#endregion
int bufIdx = currentOutSize - disp;
for (int i = 0; i < length; i++)
{
byte next = outbuffer[outbuffer.Length - 1 - bufIdx];
bufIdx++;
outbuffer[outbuffer.Length - 1 - currentOutSize] = next;
currentOutSize++;
}
}
else
{
if (readBytes >= inLength)
throw new NotEnoughDataException(currentOutSize, decompressedLength);
byte next = buffer[buffer.Length - 1 - readBytes]; readBytes++;
outbuffer[outbuffer.Length - 1 - currentOutSize] = next;
currentOutSize++;
}
}
// write the decompressed data
outstream.Write(outbuffer, 0, outbuffer.Length);
// make sure the input is positioned at the end of the file; the stream is currently
// at the compression header.
instream.Position += headerSize;
return decompressedLength + (inLength - headerSize - compressedSize);
}
}
#endregion
#region Compression method; delegates to CompressNormal
public override int Compress(System.IO.Stream instream, long inLength, System.IO.Stream outstream)
{
// don't bother trying to get the optimal not-compressed - compressed ratio for now.
// Either compress fully or don't compress (as the format cannot handle decompressed
// sizes that are smaller than the compressed file).
if (inLength > 0xFFFFFF)
throw new InputTooLargeException();
// read the input and reverse it
byte[] indata = new byte[inLength];
instream.Read(indata, 0, (int)inLength);
Array.Reverse(indata);
MemoryStream inMemStream = new MemoryStream(indata);
MemoryStream outMemStream = new MemoryStream();
int compressedLength = this.CompressNormal(inMemStream, inLength, outMemStream);
int totalCompFileLength = (int)outMemStream.Length + 8;
// make the file 4-byte aligned with padding in the header
if (totalCompFileLength % 4 != 0)
totalCompFileLength += 4 - totalCompFileLength % 4;
if (totalCompFileLength < inLength)
{
byte[] compData = outMemStream.ToArray();
Array.Reverse(compData);
outstream.Write(compData, 0, compData.Length);
int writtenBytes = compData.Length;
// there always seem to be some padding FFs. Let's pad to make the file 4-byte aligned
while (writtenBytes % 4 != 0)
{
outstream.WriteByte(0xFF);
writtenBytes++;
}
outstream.WriteByte((byte)((compressedLength) & 0xFF));
outstream.WriteByte((byte)((compressedLength >> 8) & 0xFF));
outstream.WriteByte((byte)((compressedLength >> 16) & 0xFF));
int headerLength = totalCompFileLength - compData.Length;
outstream.WriteByte((byte)headerLength);
int extraSize = (int)inLength - totalCompFileLength;
outstream.WriteByte((byte)((extraSize) & 0xFF));
outstream.WriteByte((byte)((extraSize >> 8) & 0xFF));
outstream.WriteByte((byte)((extraSize >> 16) & 0xFF));
outstream.WriteByte((byte)((extraSize >> 24) & 0xFF));
return totalCompFileLength;
}
else
{
Array.Reverse(indata);
outstream.Write(indata, 0, (int)inLength);
outstream.WriteByte(0); outstream.WriteByte(0); outstream.WriteByte(0); outstream.WriteByte(0);
return (int)inLength + 4;
}
}
#endregion
#region 'Normal' compression method. Delegates to CompressWithLA when LookAhead is set
/// <summary>
/// Compresses the given input stream with the LZ-Ovl compression, but compresses _forward_
/// instad of backwards.
/// </summary>
/// <param name="instream">The input stream to compress.</param>
/// <param name="inLength">The length of the input stream.</param>
/// <param name="outstream">The stream to write to.</param>
private unsafe int CompressNormal(Stream instream, long inLength, Stream outstream)
{
// make sure the decompressed size fits in 3 bytes.
// There should be room for four bytes, however I'm not 100% sure if that can be used
// in every game, as it may not be a built-in function.
if (inLength > 0xFFFFFF)
throw new InputTooLargeException();
// use the other method if lookahead is enabled
if (lookAhead)
{
return CompressWithLA(instream, inLength, outstream);
}
// save the input data in an array to prevent having to go back and forth in a file
byte[] indata = new byte[inLength];
int numReadBytes = instream.Read(indata, 0, (int)inLength);
if (numReadBytes != inLength)
throw new StreamTooShortException();
int compressedLength = 0;
fixed (byte* instart = &indata[0])
{
// we do need to buffer the output, as the first byte indicates which blocks are compressed.
// this version does not use a look-ahead, so we do not need to buffer more than 8 blocks at a time.
byte[] outbuffer = new byte[8 * 2 + 1];
outbuffer[0] = 0;
int bufferlength = 1, bufferedBlocks = 0;
int readBytes = 0;
while (readBytes < inLength)
{
#region If 8 blocks are bufferd, write them and reset the buffer
// we can only buffer 8 blocks at a time.
if (bufferedBlocks == 8)
{
outstream.Write(outbuffer, 0, bufferlength);
compressedLength += bufferlength;
// reset the buffer
outbuffer[0] = 0;
bufferlength = 1;
bufferedBlocks = 0;
}
#endregion
// determine if we're dealing with a compressed or raw block.
// it is a compressed block when the next 3 or more bytes can be copied from
// somewhere in the set of already compressed bytes.
int disp;
int oldLength = Math.Min(readBytes, 0x1001);
int length = LZUtil.GetOccurrenceLength(instart + readBytes, (int)Math.Min(inLength - readBytes, 0x12),
instart + readBytes - oldLength, oldLength, out disp);
// disp = 1 cannot be stored.
if (disp == 1)
{
length = 1;
}
// disp = 2 cannot be saved properly. use a too large disp instead.
// however since I'm not sure if that's actually how that's handled, don't compress instead.
else if (disp == 2)
{
length = 1;
/*if (readBytes < 0x1001)
disp = readBytes + 1;
else
length = 1;/**/
}
// length not 3 or more? next byte is raw data
if (length < 3)
{
outbuffer[bufferlength++] = *(instart + (readBytes++));
}
else
{
// 3 or more bytes can be copied? next (length) bytes will be compressed into 2 bytes
readBytes += length;
// mark the next block as compressed
outbuffer[0] |= (byte)(1 << (7 - bufferedBlocks));
outbuffer[bufferlength] = (byte)(((length - 3) << 4) & 0xF0);
outbuffer[bufferlength] |= (byte)(((disp - 3) >> 8) & 0x0F);
bufferlength++;
outbuffer[bufferlength] = (byte)((disp - 3) & 0xFF);
bufferlength++;
}
bufferedBlocks++;
}
// copy the remaining blocks to the output
if (bufferedBlocks > 0)
{
outstream.Write(outbuffer, 0, bufferlength);
compressedLength += bufferlength;
/*/ make the compressed file 4-byte aligned.
while ((compressedLength % 4) != 0)
{
outstream.WriteByte(0);
compressedLength++;
}/**/
}
}
return compressedLength;
}
#endregion
#region Dynamic Programming compression method
/// <summary>
/// Variation of the original compression method, making use of Dynamic Programming to 'look ahead'
/// and determine the optimal 'length' values for the compressed blocks. Is not 100% optimal,
/// as the flag-bytes are not taken into account.
/// </summary>
private unsafe int CompressWithLA(Stream instream, long inLength, Stream outstream)
{
// save the input data in an array to prevent having to go back and forth in a file
byte[] indata = new byte[inLength];
int numReadBytes = instream.Read(indata, 0, (int)inLength);
if (numReadBytes != inLength)
throw new StreamTooShortException();
int compressedLength = 0;
fixed (byte* instart = &indata[0])
{
// we do need to buffer the output, as the first byte indicates which blocks are compressed.
// this version does not use a look-ahead, so we do not need to buffer more than 8 blocks at a time.
byte[] outbuffer = new byte[8 * 2 + 1];
outbuffer[0] = 0;
int bufferlength = 1, bufferedBlocks = 0;
int readBytes = 0;
// get the optimal choices for len and disp
int[] lengths, disps;
this.GetOptimalCompressionLengths(instart, indata.Length, out lengths, out disps);
int optCompressionLength = this.GetOptimalCompressionPartLength(lengths);
while (readBytes < optCompressionLength)
{
// we can only buffer 8 blocks at a time.
if (bufferedBlocks == 8)
{
outstream.Write(outbuffer, 0, bufferlength);
compressedLength += bufferlength;
// reset the buffer
outbuffer[0] = 0;
bufferlength = 1;
bufferedBlocks = 0;
}
if (lengths[readBytes] == 1)
{
outbuffer[bufferlength++] = *(instart + (readBytes++));
}
else
{
// mark the next block as compressed
outbuffer[0] |= (byte)(1 << (7 - bufferedBlocks));
outbuffer[bufferlength] = (byte)(((lengths[readBytes] - 3) << 4) & 0xF0);
outbuffer[bufferlength] |= (byte)(((disps[readBytes] - 3) >> 8) & 0x0F);
bufferlength++;
outbuffer[bufferlength] = (byte)((disps[readBytes] - 3) & 0xFF);
bufferlength++;
readBytes += lengths[readBytes];
}
bufferedBlocks++;
}
// copy the remaining blocks to the output
if (bufferedBlocks > 0)
{
outstream.Write(outbuffer, 0, bufferlength);
compressedLength += bufferlength;
}
while (readBytes < inLength)
outstream.WriteByte(*(instart + (readBytes++)));
}
return compressedLength;
}
#endregion
#region DP compression helper method; GetOptimalCompressionLengths
/// <summary>
/// Gets the optimal compression lengths for each start of a compressed block using Dynamic Programming.
/// This takes O(n^2) time.
/// </summary>
/// <param name="indata">The data to compress.</param>
/// <param name="inLength">The length of the data to compress.</param>
/// <param name="lengths">The optimal 'length' of the compressed blocks. For each byte in the input data,
/// this value is the optimal 'length' value. If it is 1, the block should not be compressed.</param>
/// <param name="disps">The 'disp' values of the compressed blocks. May be less than 3, in which case the
/// corresponding length will never be anything other than 1.</param>
private unsafe void GetOptimalCompressionLengths(byte* indata, int inLength, out int[] lengths, out int[] disps)
{
lengths = new int[inLength];
disps = new int[inLength];
int[] minLengths = new int[inLength];
for (int i = inLength - 1; i >= 0; i--)
{
// first get the compression length when the next byte is not compressed
minLengths[i] = int.MaxValue;
lengths[i] = 1;
if (i + 1 >= inLength)
minLengths[i] = 1;
else
minLengths[i] = 1 + minLengths[i + 1];
// then the optimal compressed length
int oldLength = Math.Min(0x1001, i);
// get the appropriate disp while at it. Takes at most O(n) time if oldLength is considered O(n)
// be sure to bound the input length with 0x12, as that's the maximum length for LZ-Ovl compressed blocks.
int maxLen = LZUtil.GetOccurrenceLength(indata + i, Math.Min(inLength - i, 0x12),
indata + i - oldLength, oldLength, out disps[i]);
if (disps[i] > i)
throw new Exception("disp is too large");
// disp < 3 cannot be stored explicitly.
if (disps[i] < 3)
maxLen = 1;
for (int j = 3; j <= maxLen; j++)
{
int newCompLen;
if (i + j >= inLength)
newCompLen = 2;
else
newCompLen = 2 + minLengths[i + j];
if (newCompLen < minLengths[i])
{
lengths[i] = j;
minLengths[i] = newCompLen;
}
}
}
// we could optimize this further to also optimize it with regard to the flag-bytes, but that would require 8 times
// more space and time (one for each position in the block) for only a potentially tiny increase in compression ratio.
}
#endregion
#region DP compression helper method: GetOptimalCompressionPartLength
/// <summary>
/// Gets the 'optimal' length of the compressed part of the file.
/// Or rather: the length in such a way that compressing any more will not
/// result in a shorter file.
/// </summary>
/// <param name="blocklengths">The lengths of the compressed blocks, as gotten from GetOptimalCompressionLengths.</param>
/// <returns>The 'optimal' length of the compressed part of the file.</returns>
private int GetOptimalCompressionPartLength(int[] blocklengths)
{
// first determine the actual total compressed length using the optimal compression.
int block8Idx = 0;
int insideBlockIdx = 0;
int totalCompLength = 0;
for (int i = 0; i < blocklengths.Length; )
{
if (insideBlockIdx == 8)
{
block8Idx++;
insideBlockIdx = 0;
totalCompLength++;
}
insideBlockIdx++;
if (blocklengths[i] >= 3)
totalCompLength += 2;
else
totalCompLength++;
i += blocklengths[i];
}
int[] actualRestCompLengths = new int[blocklengths.Length];
block8Idx = 0;
insideBlockIdx = 0;
for (int i = 0; i < blocklengths.Length; )
{
if (insideBlockIdx == 8)
{
block8Idx++;
insideBlockIdx = 0;
totalCompLength--;
}
if (blocklengths[i] >= 3)
totalCompLength -= 2;
else
totalCompLength--;
actualRestCompLengths[i] = totalCompLength;
i += blocklengths[i];
insideBlockIdx++;
if (totalCompLength > (blocklengths.Length - i))
return i;
}
return blocklengths.Length;
}
#endregion
}
}