Refactoring.

2 files changed, 61 insertions, 3 deletions

diff --git a/FamicomDumperConnection/Crc16Calculator.cs b/FamicomDumperConnection/Crc16Calculator.cs
new file mode 100644
index 0000000..3605e5a
--- /dev/null
+++ b/FamicomDumperConnection/Crc16Calculator.cs
@@ -0,0 +1,48 @@
+namespace com.clusterrr.Famicom.DumperConnection
+{
+    public static class Crc16Calculator
+    {
+        static readonly ushort[] table = {
+            0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1,
+            0xC481, 0x0440, 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
+            0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41, 0x1400, 0xD4C1,
+            0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040, 0xF001, 0x30C0, 0x3180, 0xF141,
+            0x3300, 0xF3C1, 0xF281, 0x3240, 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0,
+            0x3E80, 0xFE41, 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
+            0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, 0x2200, 0xE2C1,
+            0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, 0x6600, 0xA6C1, 0xA781, 0x6740,
+            0xA501, 0x65C0, 0x6480, 0xA441, 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1,
+            0xA881, 0x6840, 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
+            0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, 0x5000, 0x90C1,
+            0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, 0x9C01, 0x5CC0, 0x5D80, 0x9D41,
+            0x5F00, 0x9FC1, 0x9E81, 0x5E40, 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1,
+            0x8A81, 0x4A40, 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
+            0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040, };
+
+        /// <summary>
+        /// Calculate CRC16 checksum
+        /// </summary>
+        /// <param name="data">Input data</param>
+        /// <param name="offset">Data offset</param>
+        /// <param name="length">Length</param>
+        /// <returns>CRC16 checksum</returns>
+        public static ushort CalculateCRC16(byte[] data, int offset, int length)
+        {
+            // Calculate CRC16
+            ushort crc = 0;
+            for (int i = offset; length > 0; i++, length--)
+            {
+                crc = (ushort)((crc >> 8) ^ table[((crc ^ data[i]) & 0x00FF) & 0xFF]);
+            }
+            return crc;
+        }
+
+        /// <summary>
+        /// Calculate CRC16 checksum
+        /// </summary>
+        /// <param name="data">Input date</param>
+        /// <returns>CRC16 checksum</returns>
+        public static ushort CalculateCRC16(byte[] data)
+            => CalculateCRC16(data, 0, data.Length);
+    }
+}
diff --git a/FamicomDumperConnection/FamicomDumperLocal.cs b/FamicomDumperConnection/FamicomDumperLocal.cs
index 45d36e9..10ce212 100644
--- a/FamicomDumperConnection/FamicomDumperLocal.cs
+++ b/FamicomDumperConnection/FamicomDumperLocal.cs
@@ -650,9 +650,19 @@ namespace com.clusterrr.Famicom.DumperConnection
         public void SetCoolboyGpioMode(bool coolboyGpioMode)

         {

             if (ProtocolVersion < 4)

-                throw new NotSupportedException("Dumper firmware version is too old");

-            if (HardwareVersion == null || HardwareVersion.Major < 3)

-                throw new NotSupportedException("Not supported by this dumper hardware");

+            {

+                if (coolboyGpioMode)

+                    throw new NotSupportedException("Dumper firmware version is too old");

+                else

+                    return;

+            }

+            if ((HardwareVersion == null) || (HardwareVersion.Major < 3))

+            {

+                if (coolboyGpioMode)

+                    throw new NotSupportedException("Not supported by this dumper hardware");

+                else

+                    return;

+            }

             SendCommand(DumperCommand.COOLBOY_GPIO_MODE, new byte[] { (byte)(coolboyGpioMode ? 1 : 0) });

             var (Command, Data) = RecvCommand();

             if (Command != DumperCommand.SET_VALUE_DONE)