Added Save Feature

YOOOOO It works!

WindowsFormsApp8/Form1.cs

@@ -28,7 +28,7 @@ private void button1_Click(object sender, EventArgs e)
 
             using (OpenFileDialog openFileDialog = new OpenFileDialog())
             {
-                openFileDialog.InitialDirectory = "c:\\";
+                openFileDialog.InitialDirectory = "C:\\Users\\Felix\\Downloads\\txtstuff";
                 openFileDialog.Filter = "XCP files (*.xcp)|*.xcp";
                 openFileDialog.FilterIndex = 1;
                 openFileDialog.RestoreDirectory = true;
@@ -123,31 +123,50 @@ void DecodeFile(byte[] fileContent) {
         }
 
         byte[] EncodeFile() {
+            byte checksum = 0;
             List<byte> xcpFile = new List<byte>();
             //Add the Header (VCP.XDATA�5f4d4353)
             xcpFile.AddRange(new byte[] { 0x56, 0x43, 0x50, 0x2E, 0x58, 0x44, 0x41, 0x54, 0x41, 0x00, 0x35, 0x66, 0x34, 0x64, 0x34, 0x33, 0x35, 0x33 });
+
+            foreach (byte b in new byte[] { 0x56, 0x43, 0x50, 0x2E, 0x58, 0x44, 0x41, 0x54, 0x41, 0x00 }) {
+                checksum-=b;
+            }
+            checksum -= 0x5f;
+            checksum -= 0x4d;
+            checksum -= 0x43;
+            checksum -= 0x53;
             //Add the Folderlength + the Schwarzenegger
-            char[] Folderlength = (richTextBox2.Text.Length+1).ToString("X4").ToCharArray();
+            char[] Folderlength = (richTextBox2.Text.Length+1).ToString("X2").ToCharArray();
+            foreach (byte b in BitConverter.GetBytes(richTextBox2.Text.Length + 1)) {
+                checksum -= b;
+            }
             foreach (char c in Folderlength) {
                 xcpFile.Add(Convert.ToByte(c));
             }
             //Add the Foldername and the 0x00 Terminator
            char[] Folder =richTextBox2.Text.ToCharArray();
             foreach (char c in Folder) {
                 xcpFile.Add(Convert.ToByte(c));
+                checksum -= Convert.ToByte(c);
             }
             xcpFile.Add(0x00);
-            //Add the Folderlength + the Schwarzenegger
-            char[] Filenamelength = (richTextBox1.Text.Length + 1).ToString("X4").ToCharArray();
+
+            //Add the Filenamelength + the Schwarzenegger
+            char[] Filenamelength = (richTextBox1.Text.Length + 1).ToString("X2").ToCharArray();
             foreach (char c in Filenamelength)
             {
                 xcpFile.Add(Convert.ToByte(c));
             }
-            //Add the Foldername and the 0x00 Terminator
+            foreach (byte b in BitConverter.GetBytes(richTextBox1.Text.Length + 1))
+            {
+                checksum -= b;
+            }
+            //Add the Filename and the 0x00 Terminator
             char[] Filename = richTextBox1.Text.ToCharArray();
             foreach (char c in Filename)
             {
                 xcpFile.Add(Convert.ToByte(c));
+                checksum -= Convert.ToByte(c);
             }
             xcpFile.Add(0x00);
             //add 8 Bytes of 00000031 (but the num is a String!)
@@ -156,40 +175,41 @@ byte[] EncodeFile() {
             {
                 xcpFile.Add(Convert.ToByte(c));
             }
+            checksum -= 0x31;
             // add the foldername again, but it has to be 16 bytes and if smaller padded with 0xff
-            bool addedFolder = false;
-            for (int i = 0; i == 16; i++)
+
+            for (int i = 0; i < 16; i++)
             {
-                if (addedFolder == false)
+                if (i >= Folder.Length)
                 {
-                    foreach (char c in Folder)
-                    {
-                        xcpFile.Add(Convert.ToByte(c));
-                        i++;
-                    }
-                    addedFolder = true;
+                    xcpFile.Add(0xff);
+                    checksum -= 0xff;
                 }
-                xcpFile.Add(0xff);
+                else {
+                    xcpFile.Add(Convert.ToByte(Folder[i]));
+                    checksum -= Convert.ToByte(Folder[i]);
+                }
+
             }
-
-            bool addedFilename = false;
-            for (int i = 0; i == 16; i++)
+            //same for filename
+            for (int i = 0; i < 16; i++)
             {
-                if (addedFilename == false)
+                if (i >= Filename.Length)
                 {
-                    foreach (char c in Filename)
-                    {
-                        xcpFile.Add(Convert.ToByte(c));
-                        i++;
-                    }
-                    addedFilename = true;
+                    xcpFile.Add(0xff);
+                    checksum -= 0xff;
+                }
+                else {
+                    xcpFile.Add(Convert.ToByte(Filename[i]));
+                    checksum -= Convert.ToByte(Filename[i]);
                 }
-                xcpFile.Add(0xff);
+
             }
+
             //nextup is the length of the Datablock, so i just make it now and check it like that
             List<byte> DataBlock = new List<byte>();
             UInt32 length = (UInt32) richTextBox3.Text.Length + 3;
-            DataBlock.AddRange(BitConverter.GetBytes(length).Reverse());
+            DataBlock.AddRange(BitConverter.GetBytes(length));
             //9 Bytes of 0
             DataBlock.AddRange(new Byte[] {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 });
             //now we have to add the actual text
@@ -201,21 +221,30 @@ byte[] EncodeFile() {
             DataBlock.Add(0x00);
             DataBlock.Add(0xff);
             //and a padding that makes the length value from before a multiple of 4
-            for (; 0 == DataBlock.Count%4;) {
+            for (; 0 != DataBlock.Count%4;) {
                 DataBlock.Add(0x00);
             }
             //datablock done
             //now just add the length to the file
             UInt32 Length = (UInt32)DataBlock.Count;
-            xcpFile.AddRange(BitConverter.GetBytes(Length));
+            foreach (byte b in BitConverter.GetBytes(Length)) {
+                checksum -= b;
+            }
+            xcpFile.AddRange(BitConverter.GetBytes(Length).Reverse());
             //add the Vartype padded in 0xff
             List<byte> vartype = new List<byte>();
             vartype.AddRange(new byte[] {(byte)'G',(byte)'U',(byte)'Q'});
-            for (; vartype.Count == 13;) {
+            for (; vartype.Count < 13;) {
                 vartype.Add(0xff);
             }
+            foreach (byte b in vartype) {
+                checksum -= b;
+            }
             xcpFile.AddRange(vartype);
-            char[] lenn = Length.ToString("x16").ToCharArray();
+            char[] lenn = Length.ToString("x8").ToCharArray();
+            foreach (byte b in BitConverter.GetBytes(Length)) {
+                checksum -= b;
+            }
             List<byte> len = new List<byte>();
             foreach (char c in lenn) {
 
@@ -225,38 +254,14 @@ byte[] EncodeFile() {
             xcpFile.AddRange(len);
             //add the DataBlock
             xcpFile.AddRange(DataBlock);
-            //calculate the checksum
-            int checksum = 0;
-            foreach (byte b in xcpFile) {
+            foreach (byte b in DataBlock) {
                 checksum -= b;
             }
-            List<byte> HexAsciis = new List<byte>();
-            UInt64 longnum = 0x5f4d4353;
-            byte[]longnumber = BitConverter.GetBytes(longnum);
-            foreach (byte b in longnumber) {
-                HexAsciis.Add(b);
-            }
-            //we need to add the Foldernamelength
-            foreach (char c in Folderlength)
-            {
-                HexAsciis.Add(Convert.ToByte(c));
-            }
-            foreach (char c in Filenamelength)
-            {
-                HexAsciis.Add(Convert.ToByte(c));
-            }
-            HexAsciis.AddRange(new byte[] { 30, 30, 30, 30, 30, 30, 33, 31 });
-            HexAsciis.AddRange(len);
-            // now add every element of HexAsciis to the Checksum
-            foreach (byte b in HexAsciis) {
-                checksum += b;
-            }
 
-            foreach (byte b in HexAsciis)
-            {
-                checksum -= Int32.Parse(b.ToString());
+            char[] chekksum = checksum.ToString("x2").ToCharArray();
+            foreach (char c in chekksum) {
+                xcpFile.Add((byte)c);
             }
-            xcpFile.Add(BitConverter.GetBytes(checksum)[3]);
             return xcpFile.ToArray();