private ulong[] CreateTable()
{
ulong bit, crc;
ulong[] crctab = new ulong[256];
for (ulong i = 0; i < (ulong)crctab.Length; i++)
{
crc = i;
if (this._reflectIn)
{
crc = CrcHelper.Reflect(crc, 8);
}
crc <<= this._order - 8;
for (int j = 0; j < 8; j++)
{
bit = crc & this._crcHighBit;
crc <<= 1;
if (bit > 0)
{
crc ^= this._polynom;
}
}
if (this._reflectIn)
{
crc = CrcHelper.Reflect(crc, this._order);
}
crc &= this._crcMask;
crctab[i] = crc;
}
return(crctab);
}
/// <summary>
/// Uses a fast lookup table algorithm without augmented zero bytes to produce a CRC for the provided input.
/// </summary>
/// <remarks>
/// This algorithm is only usable for polynomial orders of 8, 16, 24 or 32.
/// </remarks>
/// <param name="input">The target of the CRC.</param>
/// <returns>A <see cref="UInt64"/> containing the CRC value that was calculated for the provided input.</returns>
public ulong CalculateCrc(byte[] input)
{
ulong crc = this._crcInitialDirect;
if (_reflectIn)
{
crc = CrcHelper.Reflect(crc, this._order);
}
int len = input.Length;
int index = 0;
if (!this._reflectIn)
{
while (len-- > 0)
{
crc = (crc << 8) ^ this._table[((crc >> (this._order - 8)) & 0xff) ^ input[index++]];
}
}
else
{
while (len-- > 0)
{
crc = (crc >> 8) ^ this._table[(crc & 0xff) ^ input[index++]];
}
}
if (this._reflectOut ^ this._reflectIn)
{
crc = CrcHelper.Reflect(crc, this._order);
}
crc ^= this._crcXor;
crc &= this._crcMask;
return(crc);
}