diff --git a/libsharperang/CRC32.cs b/libsharperang/CRC32.cs
new file mode 100644
index 0000000..01fcb97
--- /dev/null
+++ b/libsharperang/CRC32.cs
@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace libsharperang {
+	public class CRC32 {
+		public uint Initial { get; private set; } = 0xFFFFFFFF;
+		private uint Polynomial = 0xedb88320;
+		//private uint Polynomial = 0x04c11db7;
+		private uint[] Table;
+		public bool Initialised=false;
+		public CRC32(uint Initial) => this.Initial=Initial;
+		public CRC32() { }
+		public void Initialise() {
+			Table=Enumerable.Range(0, 256).Select(i => {
+				uint e=(uint)i;
+				for (ushort eb = 0; eb<8; ++eb) {
+					e=((e&1)!=0)
+						? (Polynomial^(e>>1))
+						: (e>>1);
+				}
+				return e;
+			}).ToArray();
+			Initialised=true;
+		}
+		public uint Reflect(uint iv) {
+			uint ivr=0;
+			for (int i = 0; i<32; i++) {
+				uint bit=(iv>>i)&1;
+				ivr |= (bit<<(31-i));
+			}
+			return ~ivr;
+		}
+		public uint GetChecksum<T>(IEnumerable<T> bytes) {
+			if (!Initialised) Initialise();
+			try {
+				return ~bytes.Aggregate(Initial,
+					(csR, cB) => Table[(csR & 0xFF) ^ Convert.ToByte(cB)] ^ (csR>>8));
+			} catch (FormatException e) {
+				throw new Exception("Could not read stream as bytes", e);
+			} catch (InvalidCastException e) {
+				throw new Exception("Could not read stream as bytes", e);
+			} catch (OverflowException e) {
+				throw new Exception("Could not read stream as bytes", e);
+			}
+		}
+	}
+}
diff --git a/libsharperang/DataTransforms.cs b/libsharperang/DataTransforms.cs
index 4635f31..84c076d 100644
--- a/libsharperang/DataTransforms.cs
+++ b/libsharperang/DataTransforms.cs
@@ -3,29 +3,40 @@ using Crc;
 
 namespace libsharperang {
 	public class DataTransforms {
-		public class CrcSum : Crc32Base {
+		/*public class CrcSum : Crc32Base {
 			public uint CrcKey;
 			public CrcSum(uint Mangled, uint Key) : base(0x04c11db7, Mangled, 0xffffffff, true, true) => CrcKey=Key;
 		}
-		private uint Bludgeon(uint iv) {
-			uint ivr=0;
-			for (int i=0;i<32;i++) {
-				uint bit=(iv>>i)&1;
-				ivr |= (bit<<(31-i));
-			}
-			return ~ivr;
+		
+		public CrcSum CRC;*/
+		public CRC32 hasher;
+		private uint MagicNumber=0x35769521;
+		//public bool IsCrcInitialised() => (CRC!=null);
+		public bool IsCrcInitialised() => (hasher!=null && hasher.Initialised);
+		//public void InitialiseCrc() => CRC=new CrcSum(Bludgeon(0x77c40d4d^0x35769521), 0x77c40d4d);
+		//public void InitialiseCrc(uint Key) => CRC=new CrcSum(Bludgeon(Key), Key);
+		public void InitialiseCrc(uint Key=0x35769521) {
+			if (hasher==null || (hasher.Initialised && hasher.Initial != Key)) hasher=new CRC32(Key);
+			hasher.Initialise();
+		}
+		public byte[] GetHashSum(byte[] data) {
+			if (!IsCrcInitialised()) InitialiseCrc();
+			//return CRC.ComputeHash(data);
+			return BitConverter.GetBytes(hasher.GetChecksum(data));
 		}
-		public CrcSum CRC;
-		public bool IsCrcInitialised() => (CRC!=null);
-		public void InitialiseCrc() => CRC=new CrcSum(Bludgeon(0x77c40d4d^0x35769521), 0x77c40d4d);
-		public void InitialiseCrc(uint Key) => CRC=new CrcSum(Bludgeon(Key), Key);
 		public uint GetCrcKey() {
 			if (!IsCrcInitialised()) InitialiseCrc();
-			return CRC.CrcKey;
+			//return CRC.CrcKey;
+			return (hasher.Initial == MagicNumber? hasher.Initial : hasher.Initial ^ MagicNumber);
 		}
 		public byte[] GetCrcKeyBytes() {
 			if (!IsCrcInitialised()) InitialiseCrc();
 			return BitConverter.GetBytes(GetCrcKey());
 		}
+		public uint SwapEndianness(uint value) => (
+			(value & 0x000000FFU) << 24) |
+			((value & 0x0000FF00U) << 8) |
+			((value & 0x00FF0000U) >> 8) |
+			((value & 0xFF000000U) >> 24);
 	}
 }
diff --git a/libsharperang/usb.cs b/libsharperang/usb.cs
index 6451efc..9b16755 100644
--- a/libsharperang/usb.cs
+++ b/libsharperang/usb.cs
@@ -62,6 +62,7 @@ using LibUsbDotNet.Main;
 namespace libsharperang {
 	public class Frame {
 		public DataTransforms transformer=new DataTransforms();
+
 		public enum Opcode {
 			SessionBegin = 10,
 			SessionEnd,
@@ -69,6 +70,8 @@ namespace libsharperang {
 			PrintContinue,
 			CrcTransmit = 30
 		}
+		private byte FrameStart	= 0x02;
+		private byte FrameEnd		= 0x03;
 		private byte[] ResolveOpcode(Opcode opcode) {
 			switch (opcode) {
 				case Opcode.SessionBegin:  return new byte[] { 0x06, 0x00, 0x02, 0x00 };
@@ -81,24 +84,24 @@ namespace libsharperang {
 		}
 		public byte[] Build(Opcode opcode, byte[] data) => Build(opcode, data, transformer);
 		public byte[] Build(Opcode opcode, byte[] data, DataTransforms transformer) {
-			if (!transformer.IsCrcInitialised()) transformer.InitialiseCrc();
 			byte[] result=new byte[data.Length+10];
-			result[0]=0x02;
-			result[result.Length-1]=0x03;
+			result[0]=FrameStart;
+			result[result.Length-1]=FrameEnd;
 			Buffer.BlockCopy(ResolveOpcode(opcode), 0, result, 1, 4);
 			Buffer.BlockCopy(data, 0, result, 5, data.Length);
-			Buffer.BlockCopy(transformer.CRC.ComputeHash(data), 0, result, result.Length-5, 4);
+			Buffer.BlockCopy(transformer.GetHashSum(data), 0, result, result.Length-5, 4);
 			return result;
 		}
 		public byte[] BuildTransmitCrc() {
+			if (!transformer.IsCrcInitialised()) transformer.InitialiseCrc(0x77c40d4d^0x35769521);
 			DataTransforms _=new DataTransforms();
-			_.InitialiseCrc(0x35769521);
+			_.InitialiseCrc();
 			return Build(Opcode.CrcTransmit, transformer.GetCrcKeyBytes(), _);
 		}
 	}
 	public class USBPrinter : Base, IPrinter {
-    	// TODO - work out if it's possible to get this working with the default usbprint.inf driver Windows uses on plugging in
-    	//  otherwise any user would have to first use Zadig to change the driver to WinUSB
+			// TODO - work out if it's possible to get this working with the default usbprint.inf driver Windows uses on plugging in
+			//  otherwise any user would have to first use Zadig to change the driver to WinUSB
 		private UsbDevice _uDv;
 		private UsbEndpointWriter _uWr;
 		private UsbEndpointReader _uRd;