Keep only base/extractor.[cc|h].

third_party/lzma/v4_65/files/CS/7zip/Common/CRC.cs

-// 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);
-                }
-        }
-}