Initial commit

Unity Studio/7zip/Common/CRC.cs

@@ -0,0 +1,55 @@
+// Common/CRC.cs
+
+namespace SevenZip
+{
+	class CRC
+	{
+		public static readonly uint[] Table;
+
+		static CRC()
+		{
+			Table = new uint[256];
+			const uint kPoly = 0xEDB88320;
+			for (uint i = 0; i < 256; i++)
+			{
+				uint r = i;
+				for (int j = 0; j < 8; j++)
+					if ((r & 1) != 0)
+						r = (r >> 1) ^ kPoly;
+					else
+						r >>= 1;
+				Table[i] = r;
+			}
+		}
+
+		uint _value = 0xFFFFFFFF;
+
+		public void Init() { _value = 0xFFFFFFFF; }
+
+		public void UpdateByte(byte b)
+		{
+			_value = Table[(((byte)(_value)) ^ b)] ^ (_value >> 8);
+		}
+
+		public void Update(byte[] data, uint offset, uint size)
+		{
+			for (uint i = 0; i < size; i++)
+				_value = Table[(((byte)(_value)) ^ data[offset + i])] ^ (_value >> 8);
+		}
+
+		public uint GetDigest() { return _value ^ 0xFFFFFFFF; }
+
+		static uint CalculateDigest(byte[] data, uint offset, uint size)
+		{
+			CRC crc = new CRC();
+			// crc.Init();
+			crc.Update(data, offset, size);
+			return crc.GetDigest();
+		}
+
+		static bool VerifyDigest(uint digest, byte[] data, uint offset, uint size)
+		{
+			return (CalculateDigest(data, offset, size) == digest);
+		}
+	}
+}