weissman extract

extract.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
	class Program
	{
		static void Main(string[] args)
		{
			int i = 0, count = 1;
			var hashmap = new Dictionary<byte[], byte[]>();
			FileStream fs = new FileStream(args[0], FileMode.Open);
			var data = new byte[fs.Length];
			var bytelist = new List<byte>();
			fs.Read(data, 0, (int)fs.Length);
			var crc16 = new Crc16(Crc16Mode.CcittKermit);

			while(i < data.Length)
			{
				if (data[i] < 0x12)
				{
					var blocksize = data[i] / 2;
					var rel_addr = data[i + 1];
					var unknown_value = data[i + 2];
					var copyblock = new byte[blocksize];

					if (rel_addr == 0xFF)
					{
						for (int j = 1; j < blocksize + 1; j++)
							bytelist.Add(bytelist[bytelist.Count - 9 + j]);
					}
					else
					{
						for (int j = 1; j < blocksize + 1; j++)
							bytelist.Add(data[i - rel_addr + j]);
					}
					
					i += 3;
				}
				else if(data[i] == 0x12)
				{
					/*i++;
					bytelist.Add(data[i]);
					i++;
					bytelist.Add(data[i]);
					i++;*/
					i++;
					byte[] queryhash = new byte[] {data[i], data[i + 1]};
					bytelist.AddRange(hashmap[queryhash]);
					i += 2;
				}else if (data[i] == 0x13)
				{
					Console.Write("Count " + Convert.ToString(count, 16) + " ");
					count++;
					i++;
					byte[] crcinput = new byte[9];
					int sum = 0;
					for (int j = 0; j < 9; j++)
					{
						bytelist.Add(data[i + j]);
						crcinput[j] = data[i + j];
						sum += data[i + j];
						Console.Write(Convert.ToChar(data[i + j]));
					}
					var checksum = crc16.ComputeChecksumBytes(crcinput);
					//checksum[0] = (byte)(~(int)checksum[0]);
					//checksum[1] = (byte)(~(int)checksum[1]);
					hashmap.Add(checksum, crcinput);
					/*
					sum = (sum % 4096);
					var sumarr = new byte[] { (byte)((sum & 0xFF00) >> 16), (byte)(sum & 0x00FF) };
					hashmap.Add(sumarr, crcinput);
					 */
					Console.WriteLine();
					

					i += 9;
				}
			}

			FileStream nfs = new FileStream("inflated_file", FileMode.Create);
			nfs.Write(bytelist.ToArray(), 0, bytelist.Count);
			nfs.Close();
			fs.Close();

			Console.ReadLine();
		}
	}
}