将流式十六进制字符串拆分为较小的块

Question

I have a stream of hex data coming from a serial device, in this format:

F4 01 09 05 05 F4 01 09 05 05 F4 F 01 09 05 05 F4 01 09 05 05 

What I need to do (in C#) is read the incoming string, and split it into chunks at 'F4', for processing. So that I get:

string DataToProcess = "F4 01 09 05 05";

that updates as every section comes in.

I am a bit stuck as to the best way to approach this.

I have:

byte[] data = new byte[count];
 _serialPort.Read(data, 0, data.Length);

string rawString = BitConverter.ToString(data, 0);

if (rawString.Contains("F4"))
{
     //split here?                    
}

As it is a live stream, the count variable is always changing. How can I 'wait' for an F4 , and create a substring from a section?

Thank you.

Answer 1

I suggest grouping data , without converting the array into string

byte[] data = new byte[] {
    0xF4, 0x01, 0x09, 0x05, 0x05, ..., 0x09, 0x05, 0x05 };

// Using side effect in not the best practice, but helpful
int group = 0;

var result = data
  .GroupBy(item => item == 0xF4 ? ++group : group)
  .Select(chunk => chunk.ToArray());
//.ToArray(); // <- if you want to materialize

Test

string report = string.Join(Environment.NewLine, result
  .Select(array => string.Join(", ", array
     .Select(item => item.ToString("X2")))));

Console.Write(report);

Outcome

F4, 01, 09, 05, 05
F4, 01, 09, 05, 05
F4, 0F, 01, 09, 05, 05
F4, 01, 09, 05, 05

Answer 2

You can use string.Split(string[], StringSplitOptions) mixed with LINQ to split by each F4 :

if (rawString.Contains("F4"))
{
    string[] dataToProcess = rawString.Split(new string[] { "F4" }, StringSplitOptions.None).Select(l => "F4" + l).ToArray();
}

Answer 3

Use a fixed-size buffer and parse data as it comes in. Something like:

byte[] buffer = new byte[2048];
while (_serialPort.Read(data, 0, data.Length) > 0) {
    String rawString = Encoding.ASCII.GetString(buffer);
    String[] splitted = rawString.Split("\u00F4");
    // work with splitted
}

Notice that example above uses ASCII decoding instead of BitConverter.ToString . If you need to work with bytes instead, why convert it to a String in the first place? You can work with bytes as well, C# supports a syntax like 0xF4 , that would represent a number in hex format.