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BG4 plugin fix & BackwardLz77 logic revert #296

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BG4 plugin fix & BackwardLz77 logic revert #296

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02dcb4a
BG4 file names no longer save with leading slash
SomeKitten May 5, 2023
ce7cab4
Added using statement
SomeKitten May 5, 2023
9ce38c7
Revert broken BackwardLz77 implemetation
SomeKitten May 5, 2023
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5 changes: 3 additions & 2 deletions plugins/Nintendo/plugin_alpha_dream/Archives/Bg4.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
using Komponent.IO;
using Komponent.IO.Streams;
using Kompression.Implementations;
using Kontract.Extensions;
using Kontract.Models.Archive;
using Kryptography.Hash;

Expand Down Expand Up @@ -56,7 +57,7 @@ public void Save(Stream output, IList<IArchiveFileInfo> files)
var stringPosition = 0;
var stringDictionary = new Dictionary<string, int>();

foreach (var distinctString in files.Select(x => x.FilePath.FullName).Distinct())
foreach (var distinctString in files.Select(x => x.FilePath.ToRelative().FullName).Distinct())
{
stringDictionary[distinctString] = stringPosition;
stringPosition += Encoding.ASCII.GetByteCount(distinctString) + 1;
Expand All @@ -76,7 +77,7 @@ public void Save(Stream output, IList<IArchiveFileInfo> files)
var writtenSize = file.SaveFileData(output);

// Create entry
var fileName = file.FilePath.FullName;
var fileName = file.FilePath.ToRelative().FullName;
entries.Add(new Bg4Entry
{
FileOffset = filePosition,
Expand Down
169 changes: 135 additions & 34 deletions src/Kompression/Implementations/Decoders/Nintendo/BackwardLz77Decoder.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
using System.Diagnostics;
using System;
using System.Diagnostics;
using System.IO;
using Komponent.IO.Streams;
using Kompression.Extensions;
Expand All @@ -19,49 +20,149 @@ public BackwardLz77Decoder(ByteOrder byteOrder)

public void Decode(Stream input, Stream output)
{
var buffer = new byte[4];
input.Position = input.Length - 8;

input.Read(buffer, 0, 4);
var bufferTopAndBottom = _byteOrder == ByteOrder.LittleEndian ? buffer.GetInt32LittleEndian(0) : buffer.GetInt32BigEndian(0);

input.Read(buffer, 0, 4);
var decompressedOffset = _byteOrder == ByteOrder.LittleEndian ? buffer.GetInt32LittleEndian(0) : buffer.GetInt32BigEndian(0);

var footerLength = bufferTopAndBottom >> 24;
var compressedSize = bufferTopAndBottom & 0xFFFFFF;

using (var inputReverseStream = new ReverseStream(input, input.Length - footerLength))
using (var outputReverseStream = new ReverseStream(output, input.Length + decompressedOffset))
// Check if enough space exists for a footer
if (input.Length >= 8)
{
// Read footer
var buffer = new byte[4];
input.Position = input.Length - 8;

input.Read(buffer, 0, 4);
var bufferTopAndBottom = _byteOrder == ByteOrder.LittleEndian
? buffer.GetInt32LittleEndian(0)
: buffer.GetInt32BigEndian(0);

input.Read(buffer, 0, 4);
var decompressedOffset = _byteOrder == ByteOrder.LittleEndian
? buffer.GetInt32LittleEndian(0)
: buffer.GetInt32BigEndian(0);
var decompressedSize = input.Length + decompressedOffset;

var top = bufferTopAndBottom & 0xFFFFFF;
var bottom = bufferTopAndBottom >> 24 & 0xFF;

// Check footer integrity
if (bottom >= 8 && bottom <= 8 + 3 && top >= bottom && top <= input.Length &&
decompressedSize >= input.Length + decompressedOffset)
ReadCompressedData(input, output, decompressedSize, decompressedSize, input.Length - bottom,
input.Length - top);
else
{
Debugger.Break();
throw new InvalidOperationException("Something went wrong.");
}
}
else
{
var endPosition = compressedSize - footerLength;
ReadCompressedData(inputReverseStream, outputReverseStream, endPosition);
Debugger.Break();
throw new InvalidOperationException("Something went wrong.");
}

//using (var inputReverseStream = new ReverseStream(input, input.Length - footerLength))
//using (var outputReverseStream = new ReverseStream(output, input.Length + decompressedOffset))
//{
//ReadCompressedData(input, output, decompressedSize, decompressedSize, input.Length - bottom, input.Length - top);
//}
}

private void ReadCompressedData(Stream input, Stream output, long endPosition)
private void ReadCompressedData(Stream input, Stream output, long decompressedSize, long dest, long src, long end)
{
var circularBuffer = new CircularBuffer(0x1002);

var codeBlock = input.ReadByte();
var codeBlockPosition = 8;
while (input.Position < endPosition)
while (src - end > 0)
{
if (codeBlockPosition == 0)
input.Position = --src;
var flag = input.ReadByte();

for (var i = 0; i < 8; i++)
{
codeBlock = input.ReadByte();
codeBlockPosition = 8;
if (((flag << i) & 0x80) == 0)
{
if (dest - end < 1 || src - end < 1)
{
Debugger.Break();
throw new InvalidOperationException("Something went wrong.");
}

input.Position = --src;
var value = input.ReadByte();

output.Position = --dest;
output.WriteByte((byte)value);
}
else
{
if (src - end < 2)
{
Debugger.Break();
throw new InvalidOperationException("Something went wrong.");
}

input.Position = --src;
var size = input.ReadByte();

input.Position = --src;
var offset = (((size & 0x0F) << 8) | input.ReadByte()) + 3;
size = ((size >> 4) & 0x0F) + 3;

if(dest<0x60)
Debugger.Break();

if (size > dest - end)
{
Debugger.Break();
throw new InvalidOperationException("Something went wrong.");
}

var data = dest + offset;
if (data > decompressedSize)
{
Debugger.Break();
throw new InvalidOperationException("Something went wrong.");
}

for (var j = 0; j < size; j++)
{
output.Position = --data;
var value = output.ReadByte();

output.Position = --dest;
output.WriteByte((byte)value);
}
}

if (src - end <= 0)
break;
}

var flag = (codeBlock >> --codeBlockPosition) & 0x1;
if (flag == 0)
HandleUncompressedBlock(input, output, circularBuffer);
else
HandleCompressedBlock(input, output, circularBuffer);
}

while (input.Position < input.Length)
output.WriteByte((byte)input.ReadByte());
// Copy remaining bytes after end
input.Position = 0;
output.Position = 0;

var buffer = new byte[end];
input.Read(buffer);
output.Write(buffer);

//var circularBuffer = new CircularBuffer(0x1002);

//var codeBlock = input.ReadByte();
//var codeBlockPosition = 8;
//while (input.Position < endPosition)
//{
// if (codeBlockPosition == 0)
// {
// codeBlock = input.ReadByte();
// codeBlockPosition = 8;
// }

// var flag = (codeBlock >> --codeBlockPosition) & 0x1;
// if (flag == 0)
// HandleUncompressedBlock(input, output, circularBuffer);
// else
// HandleCompressedBlock(input, output, circularBuffer);
//}

//while (input.Position < input.Length)
// output.WriteByte((byte)input.ReadByte());
}

private void HandleUncompressedBlock(Stream input, Stream output, CircularBuffer circularBuffer)
Expand Down
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