System.Net.NetworkInformation.Ping.ComputeBufferChecksum C# (CSharp) Method

        private static ushort ComputeBufferChecksum(byte[] buffer)
        {
            // This is using the "deferred carries" approach outlined in RFC 1071.
            uint sum = 0;
            for (int i = 0; i < buffer.Length; i += 2)
            {
                // Combine each pair of bytes into a 16-bit number and add it to the sum
                ushort element0 = (ushort)((buffer[i] << 8) & 0xFF00);
                ushort element1 = (i + 1 < buffer.Length)
                                    ? (ushort)(buffer[i + 1] & 0x00FF)
                                    : (ushort)0; // If there's an odd number of bytes, pad by one octet of zeros.
                ushort combined = (ushort)(element0 | element1);
                sum += (uint)combined;
            }

            // Add back the "carry bits" which have risen to the upper 16 bits of the sum.
            while ((sum >> 16) != 0)
            {
                var partialSum = sum & 0xFFFF;
                var carries = sum >> 16;
                sum = partialSum + carries;
            }

            return (ushort)~sum;
        }
    }