ruusty
8/5/2018 - 11:32 AM

## Nmi check sum

Nmi check sum

``````
using System;
using System.Text;
using System.Linq;
/*Calculates a LUHN-10.
* 1. Double the value of alternate digits beginning with the rightmost digit
* 2. Add the individual digits comprising the products obtained in step 1 to each of the unaffected digits in the original number.
* 3. Find the next highest multiple of 10
* 4. The check digit is the value obtained in step 2 subtracted from the value obtained in step 3.
* 5. END
*/
namespace Ruusty
{
/* Reference:0610-0008 pdf.pdf
National Metering Identifier Procedure
PREPARED BY: Market Development
DOCUMENT NO: ME_GN059GN059
VERSION NO: V5.1
PREPARED FOR: National Electricity Market
EFFECTIVE DATE: August 2009

*/
public static class Nmi_Luhn10
{
public static string NmiCheckSum(string Nmi)
{
Nmi = IsNmi(Nmi);
string ReverseNmi = new string(Nmi.ToCharArray().Reverse().ToArray());
byte[] byteToCalculate = Encoding.ASCII.GetBytes(ReverseNmi);

int checksum = 0;
bool multiply = true;
foreach (byte chData in byteToCalculate)
{
int d = chData;
if (multiply)
{
d *= 2;
}
multiply = !multiply;
while (d > 0)
{
checksum += d % 10;
d /= 10;
}
}
checksum  = (10 - (checksum % 10)) % 10;
return checksum.ToString();
}
private static string IsNmi(string Nmi)
{
if (!(Nmi.Length == 10 || Nmi.Length == 11))
{
throw new ArgumentException("Not a NMI (Length not in 10,11");
}
Nmi = Nmi.ToUpper().Substring(0, 10);
byte[] byteToCalculate = Encoding.ASCII.GetBytes(Nmi);
foreach (byte i in byteToCalculate)
{
//41 - 90 [A-Z]
//30 - 39 [0-9]
if (!((i >= 30 && i <= 39) || (i >= 41 && i <= 90)))
{
throw new ArgumentException("Not a NMI character");
}

}
return Nmi;
}
public static string NmiWithChecksum(string Nmi)
{
return IsNmi(Nmi) + NmiCheckSum(Nmi);
}
}
}
``````