internal static MemoryStream ZLibCompress(IntPtr memoryAddress, int memoryLength)
{
MemoryStream compressedStream = new MemoryStream();
compressedStream.Write(new byte[] { 0x78, 0x01 }, 0, 2);
byte[] buffer = new byte[1024];
AdlerHolder adlerHolder = new AdlerHolder();
using (DeflateStream deflate = new DeflateStream(compressedStream, CompressionLevel.Optimal, true))
{
while (memoryLength > 0)
{
int currentBytes = Math.Min(memoryLength, 1024);
Marshal.Copy(memoryAddress, buffer, 0, currentBytes);
deflate.Write(buffer, 0, currentBytes);
memoryLength -= currentBytes;
memoryAddress = IntPtr.Add(memoryAddress, currentBytes);
Adler32(buffer, currentBytes, adlerHolder);
}
}
uint checksum = (adlerHolder.s2 << 16) + adlerHolder.s1;
compressedStream.Write(new byte[] { (byte)((checksum >> 24) & 255), (byte)((checksum >> 16) & 255), (byte)((checksum >> 8) & 255), (byte)(checksum & 255) }, 0, 4);
compressedStream.Seek(0, SeekOrigin.Begin);
return(compressedStream);
}
internal static void Adler32(byte[] buffer, int length, AdlerHolder holder)
{
for (int i = 0; i < length; i++)
{
holder.s1 = (holder.s1 + buffer[i]) % 65521U;
holder.s2 = (holder.s2 + holder.s1) % 65521U;
}
}
