Hi, I am trying to créate a CRC Xmodem calculator. I write a number, and the program is supposed to generate the CRC Xmodem 4 character code of that number.
So far, I managed to calculate the CRC Kermit and the CRC-16, but I am not able to find how to calculate the CRC Xmodem number. Thanks in advance for the help.
string input_number;
int input_number_length;
string stringArray = "";
string[] str_parsed = new string[4096];
int[] input_bytes = new int[4096];
int stringStart = 0;
int initial_crc = 0x0000;
int initial_Coefficient = 0x8408;
int lessSignificantB, crcByteA, crcByteB;
input_number = textoTrama.Text;
if (input_number.Length % 2 != 0)
{
input_number = input_number + " ";
}
input_number_length = input_number.Length/2;
//************* Divide the string *************
for (int k = 0; k<input_number_length; k++)
{
stringArray = input_number.Substring(stringStart, 2);
str_parsed[k] = stringArray;
stringStart = stringStart + 2;
}
//******* Conversion from hex string to int *******
for (int i = 0; i < input_number_length; i++)
{
input_bytes[i] = Int32.Parse(str_parsed[i], NumberStyles.HexNumber); //Pasa el array Hex a array Int
}
//***************** Algorithm ******************
for (int i = 0; i < input_number_length; i++)
{
initial_crc = initial_crc ^ input_bytes[i];
for (int j = 0; j < 8; j++)
{
lessSignificantB = initial_crc & 0x0001; // Mask of LSB
initial_crc = initial_crc >> 1;
initial_crc = initial_crc & 0x7FFF;
if (lessSignificantB == 1)
{
initial_crc = initial_crc ^ initial_Coefficient;
}
}
}
crcByteA = initial_crc & 0x00FF;
crcByteB = (initial_crc >> 8) & 0x00FF;
miCRC.Text = crcByteA.ToString("X") + crcByteB.ToString("X");
