all CRCs in one place

CUETools.Codecs/CRCs/CRC8.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace CUETools.Codecs
+{
+
+	public class Crc8
+	{
+		const ushort poly8 = 0x07;
+		ushort[] table = new ushort[256];
+
+		public byte ComputeChecksum(byte[] bytes, int pos, int count)
+		{
+			ushort crc = 0;
+			for (int i = pos; i < pos + count; i++)
+				crc = table[crc ^ bytes[i]];
+			return (byte) crc;
+		}
+
+		public unsafe byte ComputeChecksum(byte * bytes, int pos, int count)
+		{
+			ushort crc = 0;
+			for (int i = pos; i < pos + count; i++)
+				crc = table[crc ^ bytes[i]];
+			return (byte)crc;
+		}
+
+		public Crc8()
+		{
+			int bits = 8;
+			ushort poly = (ushort) (poly8 + (1U << bits));
+			for (ushort i = 0; i < table.Length; i++)
+			{
+				ushort crc = i;
+				for (int j = 0; j < bits; j++)
+				{
+					if ((crc & (1U << (bits - 1))) != 0)
+						crc = (ushort)((crc << 1) ^ poly);
+					else
+						crc <<= 1;
+				}
+				table[i] = (ushort)(crc & 0x00ff);
+			}
+		}
+	}
+}