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CRC-CCITT 16 bit Calculation in C#

I am trying to write one program for serial port communication, where i need to send data packet with CRC, I am writing this code in C# language.
Below is sample packet which receiver is expecting with CRC.
10 02 B1 F0 3F 32 08 00 00 10 03 B4 5C
Second Data Packet : 10 02 B1 F0 3F 32 07 00 00 10 03 4D EE
10 - DLE Code
02 - STX
B1 F0 3F 32 08 00 00 are Data
10 - DLE
03 -ETX
B4 - CRC Lower Bye
5C - CRC -Upper Bye
CCIT : (Fx) = x16 + x12 + x5 + 1
Operational Initial Value: FFFFH
I tried some online CRC calculators but so far no luck, can anybody guide how to calculate CRC for above data(B1 F0 3F 32 08 00 00)? may be can suggest online calculator which can give me above output(B4 5C).
Thanks for your advise!

I found something that works, but it seems a bit strange.
First I xor'ed the two samples
10 02 B1 F0 3F 32 08 00 00 10 03 B4 5C
10 02 B1 F0 3F 32 07 00 00 10 03 4D EE
--------------------------------------
00 00 00 00 00 00 0F 00 00 00 00 F9 B2
This eliminates the initial CRC and final xor values, and led to using a bit reflected 0x11021 CRC. It appears that the CRC is using 8 bytes of data, including the trailing 0x10.
Using the CRC calculator linked to below, pick any CRC16, then click on custom and set parameters to: input reflected checked, output reflected checked, poly = 0x1021. There's not enough information to determine the initial value and final xor value without a different sized message. Using 8 bytes of data, some example options are: initial value = 0x5B08, final xor value = 0x0000, or initial value = 0xffff, final xor value = 0xdde5, or initial value = 0x0000, final xor value = 0xa169.
When using reflected parameters, the calculator bit reverses the init value (0x5B08 is 0x17DA bit reversed). For code, the 3 combos are {0x17da,0x0000}, (0xffff,0xdde5}, {0x0000,0xa169}. Poly = 0x8408 and is right shifting.
Using xx's to indicate ingored data, I got
xx xx B1 F0 3F 32 08 00 00 10 xx B4 5C
xx xx B1 F0 3F 32 07 00 00 10 xx 4D EE
Since the first two bytes are {10 02}, fixed values, they could be included, by changing the initial value. However, I wasn't able to include the ETX 03 value.
http://www.sunshine2k.de/coding/javascript/crc/crc_js.html

Second hit I've found on the web but I copied it's contents here for reference:
using System;
public enum InitialCrcValue { Zeros, NonZero1 = 0xffff, NonZero2 = 0x1D0F }
public class Crc16Ccitt {
const ushort poly = 4129;
ushort[] table = new ushort[256];
ushort initialValue = 0;
public ushort ComputeChecksum(byte[] bytes) {
ushort crc = this.initialValue;
for(int i = 0; i < bytes.Length; ++i) {
crc = (ushort)((crc << 8) ^ table[((crc >> 8) ^ (0xff & bytes[i]))]);
}
return crc;
}
public byte[] ComputeChecksumBytes(byte[] bytes) {
ushort crc = ComputeChecksum(bytes);
return BitConverter.GetBytes(crc);
}
public Crc16Ccitt(InitialCrcValue initialValue) {
this.initialValue = (ushort)initialValue;
ushort temp, a;
for(int i = 0; i < table.Length; ++i) {
temp = 0;
a = (ushort)(i << 8);
for(int j = 0; j < 8; ++j) {
if(((temp ^ a) & 0x8000) != 0) {
temp = (ushort)((temp << 1) ^ poly);
} else {
temp <<= 1;
}
a <<= 1;
}
table[i] = temp;
}
}
}
The original link: http://sanity-free.org/133/crc_16_ccitt_in_csharp.html

PSCS sharp:Smart card does not respond for send data (it returns 9F 0C - COMP 128)

This is my first question on stack, so please to be understanding for me. I'm working on project that concern communication of smart card with reader. I have got Dell Smart Card Reader Keyboard and SIM card.
My project is created using C# and pcsc-sharp.dll.
My problem is the lack of response from the card to the transmitted bit sequence. Below I added sequences that sent successively to the smart card and responses.
Reader: Dell Smart Card Reader Keyboard 0
Command send: A0 C0 00 00 20
Response: 00 00 1F 3E 3F 00 01 00 0F 55 FF 01 15 B1 05 09 05 00 83 8A 83 8A 00 8A 00 00 00 00 00 00 00 00 90 00 (it's probably okay)
Command send: A0 A4 00 00 02 7F 20
Responde: 9F 22 (it's probably okay)
Rand Data send:
A0 88 00 00 10 09 05 01 0A 05 01 0D 06 00 0E 0E 08 00 0D 01 0A
Response: 9F 0C (it's probably okay)
Command send: A0 C0 00 00 0C
Response: 9F 0C (here is bug, this is not response for data that has been sent)
Does anybody know why is this happening? If anyone see any another bugs here, please described it. Below is fragment of my code in C#:
SCardContext context = new SCardContext();
context.Establish(SCardScope.System);
//Lista of available readers
string[] listOfReaders = context.GetReaders();
if (listOfReaders.Length <= 0)
{
throw new PCSCException(SCardError.NoReadersAvailable);
}
else
{
Console.WriteLine("Reader: " + listOfReaders[0]);
}
SCardReader reader = new SCardReader(context);
SCardError error = reader.Connect(listOfReaders[0], SCardShareMode.Exclusive, SCardProtocol.T0 | SCardProtocol.T1);
CheckErr(error);
IntPtr transmissionProtocol;
switch (reader.ActiveProtocol)
{
case SCardProtocol.T0:
transmissionProtocol = SCardPCI.T0;
break;
case SCardProtocol.T1:
transmissionProtocol = SCardPCI.T1;
break;
default:
throw new PCSCException(SCardError.ProtocolMismatch, reader.ActiveProtocol.ToString());
}
byte[] receivedData = new byte[256];
byte[] commandIntroduceYourself = new byte[] { 0xA0, 0xC0, 0x00, 0x00, 0x20 };
Console.Write("->");
for (int i = 0; i < commandIntroduceYourself .Length; i++)
{
Console.Write("{0:X2} ", start[i]);
}
error = czytnik.Transmit(transmissionProtocol, commandIntroduceYourself , ref receivedData);
Console.WriteLine();
Console.Write("<-");
for (int i = 0; i < receivedData.Length; i++)
{
Console.Write("{0:X2} ", receivedData[i]);
}
Console.WriteLine();
//This command below was required by the professor. I don't know why...
byte[] commandNext = new byte[] { 0xA0, 0xA4, 0x00, 0x00, 0x02, 0x7F, 0x20 };
Console.Write("->");
for (int i = 0; i < commandNext.Length; i++)
{
Console.Write("{0:X2} ", commandNext[i]);
}
error = czytnik.Transmit(transmissionProtocol, commandNext, ref receivedData);
Console.WriteLine();
Console.Write("<-");
for (int i = 0; i < receivedData.Length; i++)
{
Console.Write("{0:X2} ", receivedData[i]);
}
Console.WriteLine();
int amountOfDataToRand = 16;
//This is my function, never mind
string data = Randomize.RandomData(amountOfDataToRand);
byte[] dataSendToCard = Randomize.StringToByteArray(data);
byte[] newArray = new byte[dataSendToCard.Length + 5];
//Below is sequence that should be added to data
dataSendToCard.CopyTo(newArray, 5);
newArray[0] = 0xA0;
newArray[1] = 0x88;
newArray[2] = 0x00;
newArray[3] = 0x00;
newArray[4] = 0x10;
dataSendToCard = newArray;
Console.WriteLine("\nData send: ");
for (int i = 0; i < dataSendToCard.Length; i++)
{
Console.Write("{0:X2} ", dataSendToCard[i]);
}
Console.WriteLine();
error = czytnik.Transmit(transmissionProtocol, dataSendToCard, ref receivedData);
CheckErr(error);
Console.Write("Data received: ");
for (int i = 0; i < receivedData.Length; i++)
{
Console.Write("{0:X2} ", receivedData[i]);
}
Console.WriteLine();
byte[] commandGetResponse = new byte[] { 0xA0, 0xC0, 0x00, 0x00,0x0c };
Console.Write("->");
for (int i = 0; i < commandGetResponse.Length; i++)
{
Console.Write("{0:X2} ", commandGetResponse[i]);
}
error = czytnik.Transmit(transmissionProtocol, commandGetResponse, ref receivedData);
Console.WriteLine();
Console.Write("<-");
for (int i = 0; i < receivedData.Length; i++)
{
Console.Write("{0:X2} ", receivedData[i]);
}
Console.WriteLine();
I read this document, but I didn't find answer. http://www.embedx.com/pdfs/ISO_STD_7816/info_isoiec7816-4%7Bed21.0%7Den.pdf

Serial Port DataReceived firing multiple times

I'm developing a winforms app that talks to a FPGA device. Since the device is still in development, I'm trying to simulate it using com0com (http://com0com.sourceforge.net/) and another winforms app as the simulator.
I'm sending a byte array of 44 bytes from my app to the simulator:
CC AA 01 28 09 2A 0C 00 01 FF 00 FA 02 FF 01 5E 03 FF 01 C2 04 FF 02 26 05 FF 02 8A 06 FF 02 EE 07 FF 03 52 08 FF 03 B6 09 FF 04 1A
The first 4 bytes are the header and the fourth byte contains the number of bytes to follow. In this case 40=0x28. There is no termination value in the API spec. Here is how I'm handling the DataRecieved event:
void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
int byte_count = 0;
int read_count = 0;
while (comPort.BytesToRead > 0)
{
byte_count = comPort.BytesToRead;
byte[] byteTemp = new byte[byte_count];
read_count = comPort.Read(byteTemp, 0, byte_count);
}
byte[] byteBuffer = new byte[read_count];
int intNumBytes2read = byteBuffer[3];
// do other stuff
}
My problem is that the simulator does not always receive the entire payload when the event fires. In fact, the event usually fires more than once each time I send data from my app to the simulator. My research on the subject indicates that this is a common problem and that I need to create some sort of queuing mechanism. With my limited C# experience, I'm struggling with the understanding of how to do this.
Any suggestions would be appreciated.

You need a state machine to keep track of how far you've progressed in the reception of a message. That can look like this:
private int state;
private byte[] payload;
private int payloadIndex;
private void comPort_DataReceived(object sender, SerialDataReceivedEventArgs e) {
while (comPort.BytesToRead > 0) {
byte b = (byte)comPort.BaseStream.ReadByte();
switch (state) {
case 0:
if (b == 0xcc) state++;
else protocolViolation("Bad header, expected 0xcc");
break;
case 1:
if (b == 0xaa) state++;
else protocolViolation("Bad header, expected 0xaa");
break;
case 2:
if (b == 0x01) state++;
else protocolViolation("Bad header, expected 0x01");
break;
case 3:
payload = new byte[b];
payloadIndex = 0;
state++;
break;
case 4:
payload[payloadIndex++] = b;
if (payloadIndex == payload.Length) {
processPayload(payload);
state = 0;
}
break;
}
}
}
private void protocolViolation(string why) {
state = 0;
Debug.WriteLine(why);
}
private void processPayload(byte[] payload) {
// etc..
}

Generate combination using string array in c# [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Different combinations of an array (C#)
string[] array = {"01", "02", "03", "04", "05", "06", "07", "08", "09", "10"};
How to generate to 2 / 3 / 4 / 5 strings per combination like for example 2 strings per combination, with no repeats/duplicates, disregard of position as well, using combination formula nCr = 10!/2!(10-2)! = 45 combinations.
I need the output to be like this:
"01", "02"
"01", "03"
"01", "04"
...
"02", "03" // eliminate the "02","01" 'cause it is same as "01","02" combination
"02", "04"
...
Then to generate combinations of 3 strings, would have 120 combinations (according to nCr).
I need the output to be like this:
"01","02","03"
"01","02","04"
...
And combinations of 4 strings, would have 210 combinations, the least, combinations of 5 strings per combination, would have 252 combinations.
How can I write that? I've used up many loops and it looks really a mess.

You could use a simple recursion:
private static IEnumerable<string> Combinations(int start, int level)
{
for ( int i = start; i < array.Length; i++ )
if ( level == 1 )
yield return array[i];
else
foreach ( string combination in Combinations(i + 1, level - 1) )
yield return String.Format("{0} {1}", array[i], combination);
}
The call it like this:
var combinations = Combinations(0, 2);
foreach ( var item in combinations )
Console.WriteLine(item);

You can use this efficient project: Permutations, Combinations, and Variations using C# Generics.
string[] array = { "01", "02", "03", "04", "05", "06", "07", "08", "09", "10" };
int lowerIndex = 2;
var combinations = new Facet.Combinatorics.Combinations<String>(
array,
lowerIndex,
Facet.Combinatorics.GenerateOption.WithoutRepetition
);
foreach (IList<String> combis in combinations)
{
String combi = String.Join(" ", combis);
Console.WriteLine(combi);
}
Since it's open source you can look how it's implemented. But the link above is also very informative.
output (lowerIndex=2):
01 02
01 03
01 04
01 05
01 06
01 07
01 08
01 09
01 10
02 03 <-- no 02 01 since it would be a repitition
02 04
02 05
// ... (45 combinations w/o repetitions)
09 10
output (lowerIndex=5):
01 02 03 04 05
01 02 03 04 06
01 02 03 04 07
01 02 03 04 08
01 02 03 04 09
01 02 03 04 10
01 02 03 05 06
01 02 03 05 07
01 02 03 05 08
01 02 03 05 09
01 02 03 05 10
01 02 03 06 07
// ........... (252 combinations w/o repetitions)
05 07 08 09 10
06 07 08 09 10

Here is the function to perform combinations for two numbers using nCr,Tweak it for multiple numbers
/// <summary>
/// Performs a nCr Combination of the two numbers
/// </summary>
/// <param name="n">The Number</param>
/// <param name="r">The Range</param>
/// <returns></returns>
public static double Combination(double n, double r)
{
/*
* Formula for Combination: n! / (r! * (n - r)!)
*/
// n and r should be integral values
double rfloor = Math.Floor(r);
double nfloor = Math.Floor(n);
// Check for all invalid values of n and r.
if ((n < 1) || (r < 0) || (r > n) || (r != rfloor) || (n != nfloor))
{
throw new Exception("Invalid Input to Combination Function: Number must be greater than Range");
}
return Factorial(n) / (Factorial(r) * Factorial(n - r));
}
And
public static double Factorial(double n)
{
if (n < 0) { throw new Exception("Cannot take the factorial of a negative number"); }
double factorial = 1;
// 0! and 1! = 1
for (double i = 2; i < n + 1; i++)
{
factorial *= i;
}
return factorial;
}

How to convert byte[] to that text format?

I can say I don't know what I'm asking for help,because I don't know the format,but I've got a picture.
I have a byte[] array ,how do I convert it to that format below(in right)?
alt text http://img512.imageshack.us/img512/3548/48667724.jpg
Its not plain ascii.

It sounds like you'd like to take an array of bytes, and convert it to text (replacing characters outside of a certain range with "."s)
static public string ConvertFromBytes(byte[] input)
{
StringBuilder output = new StringBuilder(input.Length);
foreach (byte b in input)
{
// Printable chars are from 0x20 (space) to 0x7E (~)
if (b >= 0x20 && b <= 0x7E)
{
output.Append((char)b);
}
else
{
// This isn't a text char, so use a placehold char instead
output.Append(".");
}
}
return output.ToString();
}
or as a LINQy extension method (inside a static extension class):
static public string ToPrintableString(this byte[] bytes)
{
return Encoding.ASCII.GetString
(
bytes.Select(x => x < 0x20 || x > 0x7E ? (byte)'.' : x)
.ToArray()
);
}
(You could call that like string printable = byteArray.ToPrintableString();)

Use b.ToString("x2") to format a byte value into a two character hexadecimal string.
For the ASCII display, check if the value corresponds to a regular printable character and convert it if it is:
if (b >= 32 && b <= 127) {
c = (char)b;
} else {
c = '.';
}
Or shorter:
c = b >= 32 && b <= 127 ? (char)b : '.';
To do it on an array:
StringBuilder builder = new StringBuilder();
foreach (b in theArray) {
builder.Append(b >= 32 && b <= 127 ? (char)b : '.');
}
string result = builder.ToString();

This could be any number of encodings... try this test test script to see which of them print out:
Bl8s
Here is the script:
byte[] b = new byte[] {0x42, 0x6C, 0x38, 0x73 };
foreach (EncodingInfo ei in Encoding.GetEncodings())
{
Console.WriteLine("{0} - {1}", ei.GetEncoding().GetString(b), ei.Name);
}

[edit 2018:] Re-wrote the function from scratch to make the code much more efficient and fix some other problems. You can now also optionally specify a starting offset and number of bytes (starting from there) to display.
If you want the whole memory display, including the offset number, and left and right displays, you can do it like this: (32-byte width)
/// <summary> Returns a String where the specified bytes are formatted in a
/// 3-section debugger-style aligned memory display, 32-bytes per line </summary>
public static unsafe String MemoryDisplay(byte[] mem, int i_start = 0, int c = -1)
{
if (mem == null)
throw new ArgumentNullException();
if (i_start < 0)
throw new IndexOutOfRangeException();
if (c == -1)
c = mem.Length - i_start;
else if (c < 0)
throw new ArgumentException();
if (c == 0)
return String.Empty;
char* pch = stackalloc Char[32]; // for building right side at the same time
var sb = new StringBuilder((c / 32 + 1) * 140); // exact pre-allocation
c += i_start;
for (int i = i_start & ~0x1F; i < c;)
{
sb.Append(i.ToString("x8"));
sb.Append(' ');
do
{
if (i < i_start || i >= c) // non-requested area, or past the end
{
sb.Append(" ");
pch[i & 0x1F] = ' ';
}
else
{
var b = mem[i];
sb.Append(b.ToString("x2") + " ");
pch[i & 0x1F] = non_monospace(b) ? '.' : (Char)b;
}
}
while ((++i & 0x1F) != 0);
sb.Append(' ');
sb.AppendLine(new String(pch, 0, 32));
}
return sb.ToString();
}
The code uses the following helpers to determine which characters should be shown as 'dots' in right-hand part.
static readonly ulong[] _nmb =
{
0x00000000ffffe7ffUL,
0x8000000000000000UL,
0x00002000ffffffffUL,
0x0000000000000000UL,
};
static bool non_monospace(byte b) => (_nmb[b >> 6] & 1UL << b) != 0;
Output of the above function looks like this (character width is 138 columns, scroll to the right to see the "human-readable" part):
00000000 47 49 46 38 39 61 0f 00 0f 00 91 ff 00 00 00 00 c0 c0 c0 ff ff 00 00 00 00 21 f9 04 01 00 00 01 GIF89a...................!......
00000020 00 2c 00 00 00 00 0f 00 0f 00 00 02 2c 8c 0d 99 c7 91 02 e1 62 20 5a 79 ea bd 00 6d 89 69 8a f8 .,..........,.......b Zy...m.i..
00000040 08 e5 a7 99 e9 17 9d ac 24 a2 21 68 89 1e ac b4 d9 db 51 ab da c8 8c 1a 05 00 3b ........$.!h......Q.......;

Try: Encoding.Default.GetBytes
If that doesn't work, there are different types that you can specify (UTF-8, ASCII...)