/// <summary>Calculates quad-word length (64-bit) XOR-based check-sum on specified portion of a buffer.</summary>
/// <param name="data">Data buffer to perform XOR check-sum on.</param>
/// <param name="startIndex">Starts index in data buffer to begin XOR check-sum.</param>
/// <param name="length">Total number of bytes from <paramref name="startIndex">startIndex</paramref> to
/// perform XOR check-sum over.</param>
/// <returns>Quad-word length XOR check-sum.</returns>
public static ulong Xor64Checksum(this byte[] data, int startIndex, int length)
{
Xor64 checksum = new Xor64();
checksum.Update(data, startIndex, length);
return(checksum.Value);
}
/// <summary>Calculates quad-word length (64-bit) XOR-based check-sum on specified portion of a buffer.</summary>
/// <param name="data">Data buffer to perform XOR check-sum on.</param>
/// <param name="startIndex">Starts index in data buffer to begin XOR check-sum.</param>
/// <param name="length">Total number of bytes from <paramref name="startIndex">startIndex</paramref> to
/// perform XOR check-sum over.</param>
/// <returns>Quad-word length XOR check-sum.</returns>
public static ulong Xor64Checksum(this byte[] data, int startIndex, int length)
{
Xor64 checksum = new Xor64();
checksum.Update(data, startIndex, length);
return checksum.Value;
}