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// 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);↩
}↩
}↩
}↩