/* Compress */
public static MemoryStream Compress(ref Stream data, string filename)
{
try
{
var decompressedSize = (uint)data.Length;
var compressedData = new MemoryStream();
byte[] decompressedData = data.ToByteArray();
uint sourcePointer = 0x0;
uint destPointer = 0x4;
// Test if the file is too large to be compressed
if (data.Length > 0xFFFFFF)
{
throw new Exception("Input file is too large to compress.");
}
// Set up the Lz Compression Dictionary
var lzDictionary = new LzWindowDictionary();
lzDictionary.SetWindowSize(0x1000);
lzDictionary.SetMaxMatchAmount(0xF + 3);
// Start compression
compressedData.Write('\x10' | (decompressedSize << 8));
while (sourcePointer < decompressedSize)
{
byte flag = 0x0;
var flagPosition = destPointer;
compressedData.WriteByte(flag); // It will be filled in later
destPointer++;
for (var i = 7; i >= 0; i--)
{
var lzSearchMatch = lzDictionary.Search(decompressedData, sourcePointer, decompressedSize);
if (lzSearchMatch[1] > 0) // There is a compression match
{
flag |= (byte)(1 << i);
compressedData.WriteByte((byte)((((lzSearchMatch[1] - 3) & 0xF) << 4) | (((lzSearchMatch[0] - 1) & 0xFFF) >> 8)));
compressedData.WriteByte((byte)((lzSearchMatch[0] - 1) & 0xFF));
lzDictionary.AddEntryRange(decompressedData, (int)sourcePointer, lzSearchMatch[1]);
lzDictionary.SlideWindow(lzSearchMatch[1]);
sourcePointer += (uint)lzSearchMatch[1];
destPointer += 2;
}
else // There wasn't a match
{
flag |= (byte)(0 << i);
compressedData.WriteByte(decompressedData[sourcePointer]);
lzDictionary.AddEntry(decompressedData, (int)sourcePointer);
lzDictionary.SlideWindow(1);
sourcePointer++;
destPointer++;
}
// Check for out of bounds
if (sourcePointer >= decompressedSize)
{
break;
}
}
// Write the flag.
// The original position gets reset after writing.
compressedData.Seek(flagPosition, SeekOrigin.Begin);
compressedData.WriteByte(flag);
compressedData.Seek(destPointer, SeekOrigin.Begin);
}
return(compressedData);
}
catch
{
return(null); // An error occured while compressing
}
}
/* Compress */
public static MemoryStream Compress(ref Stream data, string filename)
{
try
{
var decompressedSize = (uint)data.Length;
var compressedData = new MemoryStream();
byte[] decompressedData = data.ToByteArray();
uint sourcePointer = 0x0;
uint destPointer = 0x4;
// Test if the file is too large to be compressed
if (data.Length > 0xFFFFFF)
throw new Exception("Input file is too large to compress.");
// Set up the Lz Compression Dictionary
var lzDictionary = new LzWindowDictionary();
lzDictionary.SetWindowSize(0x1000);
lzDictionary.SetMaxMatchAmount(0xF + 3);
// Start compression
compressedData.Write('\x10' | (decompressedSize << 8));
while (sourcePointer < decompressedSize)
{
byte flag = 0x0;
var flagPosition = destPointer;
compressedData.WriteByte(flag); // It will be filled in later
destPointer++;
for (var i = 7; i >= 0; i--)
{
var lzSearchMatch = lzDictionary.Search(decompressedData, sourcePointer, decompressedSize);
if (lzSearchMatch[1] > 0) // There is a compression match
{
flag |= (byte)(1 << i);
compressedData.WriteByte((byte)((((lzSearchMatch[1] - 3) & 0xF) << 4) | (((lzSearchMatch[0] - 1) & 0xFFF) >> 8)));
compressedData.WriteByte((byte)((lzSearchMatch[0] - 1) & 0xFF));
lzDictionary.AddEntryRange(decompressedData, (int)sourcePointer, lzSearchMatch[1]);
lzDictionary.SlideWindow(lzSearchMatch[1]);
sourcePointer += (uint)lzSearchMatch[1];
destPointer += 2;
}
else // There wasn't a match
{
flag |= (byte)(0 << i);
compressedData.WriteByte(decompressedData[sourcePointer]);
lzDictionary.AddEntry(decompressedData, (int)sourcePointer);
lzDictionary.SlideWindow(1);
sourcePointer++;
destPointer++;
}
// Check for out of bounds
if (sourcePointer >= decompressedSize)
break;
}
// Write the flag.
// The original position gets reset after writing.
compressedData.Seek(flagPosition, SeekOrigin.Begin);
compressedData.WriteByte(flag);
compressedData.Seek(destPointer, SeekOrigin.Begin);
}
return compressedData;
}
catch
{
return null; // An error occured while compressing
}
}
