/// <summary>
/// Compute a CRC value for a block of data.
/// </summary>
/// <param name="data">The data from which to compute an updated running CRC.</param>
/// <param name="polynomial">The polynomial to use.</param>
/// <param name="numBytesToProcess">Number of bytes in the buffer to process (always start at first element).</param>
/// <param name="runningValue">Running value of the CRC.</param>
/// <returns>Running CRC, updated with the contents of the given data block.</returns>
private static uint OfBlock(byte[] data, Crc32Polynomial polynomial, int numBytesToProcess, uint runningValue)
{
uint[] lookupTable = null;
switch (polynomial)
{
case Crc32Polynomial.Zip:
lookupTable = Crc32Table;
break;
case Crc32Polynomial.Castagnoli:
lookupTable = Crc32CTable;
break;
default:
throw new InvalidOperationException();
}
var crc = runningValue;
for (var i = 0; i < numBytesToProcess; ++i)
{
crc = Update(crc, data[i], lookupTable);
}
return(crc);
}
/// <summary>
/// Compute a CRC value for a block of data using a specific polynomial.
/// </summary>
/// <param name="data">The data from which to compute the CRC.</param>
/// <param name="polynomial">The polynomial to use.</param>
/// <returns>The CRC of the data block.</returns>
public static uint OfBlock(byte[] data, Crc32Polynomial polynomial)
{
var initialValue = InitialValue;
switch (polynomial)
{
case Crc32Polynomial.Castagnoli:
initialValue = InitialValueZero;
break;
default:
break;
}
uint crc = OfBlock(data, polynomial, data.Length, initialValue) ^ initialValue;
return(crc);
}
