Just compress

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
//using System.IO.FileStream;

namespace C_NET_ARCHIVE
{
    /*Code byte (N)	Instructions
                            0 ? N ? 127	Interpret the next N+1 bytes literally.
                                N = 128	Reserved
                          129 ? N ? 255	Repeat the next byte 257?N times.   */

    class File
    {
        System.IO.FileStream file_to_pack, dest_file;//, temp_file;
        public void Open(string file_to_path, string file_de_path)
        {
            file_to_pack = new System.IO.FileStream(file_to_path, FileMode.Open);       //SDELAT ISKL
            dest_file = new System.IO.FileStream(file_de_path, FileMode.Create);

            encode(file_to_pack, dest_file);

            dest_file.Close();
            file_to_pack.Close();
        }

        //ИСПРАВЛЕНО ПОЛНОСТЬЮ
        public void encode(System.IO.FileStream file_to_pack, System.IO.FileStream dest_file)
        {
            BinaryWriter file = new BinaryWriter(dest_file);

            file.Write((byte)128);
            bool do_compress = false;

            #region surprise
            string[] message = { "  @\n</|\n)\\|\n\n", "  @\n</\\\n)\\ \\\n", "  @\n</ \\\n)\\ |", "  @\n// \\\n/ )|", "_ @\n /|\n/ )|", "_ @\n /|\n)\\|" };/*|||||||*/ //@"|<-\\--\'", @"\<-\\--\'", @"-<-\\--\'", @"/<-\\--\'" };        //4kadra
            int index = 0;
            #endregion

                for (;file_to_pack.Position < file_to_pack.Length;)        //i = 1 tk perviy simvol budet govorit o KOMPR
                {
                    #region surprise in action
                    if (file_to_pack.Position%400 == 100 && index < message.Length)
                    {
                        Console.Clear();
                        Console.BackgroundColor = ConsoleColor.Blue;
                        Console.ForegroundColor = ConsoleColor.White;
                        Console.Write(message[index]);

                        index++;
                    }
                    else if (index == message.Length)
                        index = 0;

                    #endregion
                    if (file_to_pack.Position != 0)
                        file_to_pack.Seek(file_to_pack.Position - 1, SeekOrigin.Begin);

                    byte count_comp = 0;
                    byte count_exact = 0;

                    long offset = file_to_pack.Position;
                    byte temp = (byte)file_to_pack.ReadByte();          //position переводится на следующую


                    while (temp == (byte)file_to_pack.ReadByte() && file_to_pack.Position - offset < 128 && file_to_pack.Position < file_to_pack.Length) ;

                    count_comp = (byte)(file_to_pack.Position - offset);

                    do_compress = (count_comp > 1) ? true : false;

                    if (do_compress == true)
                    {
                        if (257 - count_comp > 128)
                        {
                            byte count = 2;
                            count -= count_comp;// count += 1;
                            file.Write(count);
                            file.Write(temp);
                            file.Write((byte)128);
                        }
                        else
                        {
                            byte count = 2;
                            count_comp -= 129; ;// count += 1;
                            file.Write((byte)129);
                            file.Write(temp);
                            file.Write((byte)128);
                            //----------------------
                            count_comp = (byte)(count - count_comp);
                            file.Write(count_comp);
                            file.Write(temp);
                            file.Write((byte)128);
                        }
                    }
                    else
                    {
                        long offset_back = file_to_pack.Position;
                        while (file_to_pack.Position < file_to_pack.Length && temp != (byte)file_to_pack.ReadByte())
                        {
                            if (!(++count_exact < 126))     //ошибка переполнения?
                                break;
                        }
                        file.Write(++count_exact);

                        file_to_pack.Seek(offset_back, SeekOrigin.Begin);

                        while (file_to_pack.Position < file_to_pack.Length)
                            file.Write((byte)file_to_pack.ReadByte());
                        file.Write((byte)128);
                    }
                }

        }

    }
    class Unpack
        {
            System.IO.FileStream file_to_unpack, dest_file;

            public void Open(string file_to_path, string file_de_path)
            {
                file_to_unpack = new System.IO.FileStream(file_to_path, FileMode.Open);       //SDELAT ISKL
                dest_file = new System.IO.FileStream(file_de_path, FileMode.Create);
                decode(file_to_unpack, dest_file);
            }

            //ИСПРАВЛЕНО ПОЛНОСТЬЮ
            public void decode(System.IO.FileStream file_to_unpack, System.IO.FileStream dest_file)
            {
                /*Если в начале группы из 255 байт стоит 1, то  блок сжат, если 0, то нет*/

            #region surprise
            string[] message = { "  @\n</|\n)\\|\n\n", "  @\n</\\\n)\\ \\\n", "  @\n</ \\\n)\\ |", "  @\n// \\\n/ )|", "_ @\n /|\n/ )|", "_ @\n /|\n)\\|" };/*|||||||*/ //@"|<-\\--\'", @"\<-\\--\'", @"-<-\\--\'", @"/<-\\--\'" };        //4kadra
            int index = 0;
            #endregion



                byte last_byte = 0;
                for (;file_to_unpack.Position < file_to_unpack.Length-1;)
                {
                    #region surprise in action
                    if (file_to_unpack.Position % 400 == 100 && index < message.Length)
                    {
                        Console.Clear();
                        Console.BackgroundColor = ConsoleColor.DarkMagenta;
                        Console.ForegroundColor = ConsoleColor.White;
                        Console.Write(message[index]);

                        index++;
                    }
                    else if (index == message.Length)
                        index = 0;

                    #endregion

                    byte desi = (byte)file_to_unpack.ReadByte();
                    byte count = (byte)file_to_unpack.ReadByte();       //409-я позиция
                    if (count == (byte)0)
                        count = 1;
                    int wtf = 0;
                    if (desi == 128)          //decompress
                    {
                        if (count < 128)           //literal bytes
                        {
                            for (int j = 0; j < count; j++)
                                dest_file.WriteByte((byte)file_to_unpack.ReadByte());
                        }
                        else           //compressed bytes
                        {
                            byte temp = (byte)file_to_unpack.ReadByte();
                            last_byte = temp;
                            for (int j = 0; j < 257 - count; j++)
                                dest_file.WriteByte(temp);
                        }
                    }

                }
                dest_file.WriteByte(last_byte);



            }
        }

        class Program
        {
            static public void makefile(string filename, int weight)
            {
                System.IO.FileStream file_to_make = new System.IO.FileStream(filename, FileMode.Create);
                Random j = new Random();

                BinaryWriter file = new BinaryWriter(file_to_make);

                while(weight != 0)
                {
                    for (int i = 0, r = j.Next(32, 123); i < r && weight != 0; i++, weight--)
                        file.Write((byte)r);

                    //file.Write((byte)j.Next(32, 123));
                    //weight--;
                }


                file_to_make.Close();
            }
            static void Main(string[] args)
            {

                if(args[0] == "-make")
                  {
                     makefile(args[1],int.Parse(args[2]));
                  }
                 else if(args[0] != "-unpack")
                 {
                    File file = new File();
                    file.Open(args[1],args[2]);

                 }
                 else
                  {
                     Unpack file_un = new Unpack();
                     file_un.Open(args[1],args[2]);
                  }

            }
        }
    }