esiur-dotnet/Esiur/Security/Integrity/NMEA0183.cs

using System;
using System.Collections.Generic;
using System.Text;

namespace Esiur.Security.Integrity;

public class NMEA0183
{
    public static byte Compute(string data)
    {
        return Compute(data, 0, (uint)data.Length);
    }

    public static byte Compute(string data, uint offset, uint length)
    {
        byte rt = 0;
        var ends = offset + length;
        for (int i = (int)offset; i < ends; i++)
            rt ^= (byte)data[i];

        return rt;
    }
}