We Keep Coding

Delay in while loop and its precision

I am writing C# code to make data acquire system from FPGA with USB communication and not that familiar with C#.
The system received data continuously at regular intervals through USB.
Data is continuously received only when DOPPLER_NUM = 1, and while (DOPPLER_NUM == 1) is that process.
And there are two problems in operation.
When I operate code without Delay(1) in while loop, the program is completely stopped and none of the buttons in the program works.
I used Delay function to solve the problem, and it works.
But, the delay I want is 1ms and it actually varies from 1-15ms when I measured it with Stopwatch function.
public void Delay(int MS)
{
DateTime ThisMoment = DateTime.Now;
TimeSpan Duration = new TimeSpan(0, 0, 0, 0, MS);
DateTime AfterWards = DateTime.Now.Add(Duration);
while (AfterWards >= ThisMoment)
{
System.Windows.Forms.Application.DoEvents();
ThisMoment = DateTime.Now;
}
return;
}
int DOPPLER_NUM = 0;
private void Doppler_Start_Click(object sender, EventArgs e)
{
int transmit_mode = 1;
if (DOPPLER_NUM == 0)
{
DOPPLER_NUM = 1;
transmit_mode = 1;
}
else
{
DOPPLER_NUM = 0;
transmit_mode = 0;
cnt4GS = 0;
}
CyBulkEndPoint Inednpt1;
Inednpt1 = MyDevice.EndPointOf(0x86) as CyBulkEndPoint;
int bytes1 = Convert.ToInt32(256);
int bytes2 = bytes1 * 2;
bool bXferCompleted = false;
bool IsPkt = false;
byte[] buffer4GS = new byte[400 * 256];
byte[] buffer1 = new byte[bytes2];
byte[] Data_buf = new byte[bytes1];
while (DOPPLER_NUM == 1)
{
Stopwatch clk1 = new Stopwatch();
clk1.Start();
Delay(1);
clk1.Stop();
opertime.Text = (clk1.ElapsedTicks * 100 / 1000).ToString() + " us";
if (MyDevice != null)
{
if (Inednpt1 != null)
{
bXferCompleted = Inednpt1.XferData(ref buffer1, ref bytes2, IsPkt); // Data receiving from USB
Data_buf = Doppler_Processing(buffer1, bytes2);
if (cnt4GS >= 0 && cnt4GS <= 399)
{
Buffer.BlockCopy(Data_buf, 0, buffer4GS, cnt4GS * 256, 256);
cnt4GS++;
}
else if (cnt4GS >= 400)
{
Buffer.BlockCopy(buffer4GS, 256, buffer4GS, 0, 102144);
Buffer.BlockCopy(Data_buf, 0, buffer4GS, 102144, 256);
}
Grayscale(buffer4GS);
}
}
else if (MyDevice == null)
{
MessageBox.Show("ERROR. NODEVICE.", "Error Message");
break;
}
}

Your Delay method gives the UI thread to handle events, by calling System.Windows.Forms.Application.DoEvents();
If you have an intensive operation bound to your UI thread (which explains the behaviour) you'll end up with a blocked UI. The usage of System.Windows.Forms.Application.DoEvents(); can resolve this, but it would be better to just execute your DOPPLER_NUM loop in another thread - not bothering the UI thread with it and keeping your program responsive.
Alternatively, you can just call System.Windows.Forms.Application.DoEvents(); from your loop itself and it would work just as good, maybe increasing performance a bit.
Also:
Alternatives like Task.Delay and Thread.Sleep will not have a better accuracy as about 5ms. This is by design - because measuring the exact time will cost CPU power, same as the stopwatch does.

C# Why is Serial.WriteLine() so slow?

When I want to program a Teensy 3.5 micro-controller, I send it a .HEX file via a hardware serial port. I have two ways of doing this; one way is to use a serial comms app like Tera Term to send the file, and another way is via a small C# command-line app I wrote to do the same thing.
When I send a 3000+ line Hex file to the micro-controller, it takes approximately 14 seconds. When I do the same thing with my C# program, it takes twice as long (or longer!). The baud rate for both Tera Term and my C# program are the same, and of course the Teensy setup is common to both.
When I looked as the serial transfer using a digital scope, I see the following (same time scale in both photos):
The first photo shows the transfer when using Tera Term, and the second one shows the transfer when using my C# program using Serial.WriteLine() to transfer file contents line-by-line, as shown below:
using System;
using System.IO;
using System.IO.Ports;
using System.Threading;
using System.Timers;
using System.Diagnostics;
/*
Small console app to facilitate over-the-air (OTA) updates to a Teensy 3.x/4.x controller,
using VS2019 with the Visual Micro extension as the Arduino IDE. It is called by a post-build
'hook' statement in a file called 'board.txt' located in whatever Teensy program is
being updated. This app does the following:
- Extract the project path and selected COMPORT number from the arguments to the call to Main()
- Opens a UART serial port connection to the Teensy, typically one provided by a BT adaptor
operating in 'pass-through' mode. The serial port COMPORT number is passed into this app
as an argument.
- Sends whatever command is required to put the existing Teensy firmware into 'update' mode
- Using the path of the updating program (passed in as an argument), locates the .HEX file
associated with the project, and sends it's contents to the Teensy, one line at a time, counting
lines and confirming checksums line-by-line
- Compares the number of lines sent to the Teensy with the number of lines received by the Teensy,
and if there is a match, allows the Teensy update process to complete; otherwise aborts
*/
namespace TeensyFlash
{
class Program
{
const string startCmdStr = "U"; //used in sketch's 'GetUserInput()' to start upload sequence
static string rcvStr = string.Empty;
private static System.Timers.Timer aTimer;
private static bool bTimedOut;
static void Main(string[] args)
{
//Extract the build path and selected COMPORT number from the arguments to the call to Main()
Console.WriteLine("Teensy Flash Console");
Console.WriteLine("Number of arguments in args = {0}\n", args.Length);
int argindex = 0;
string comPortStr = string.Empty;
foreach (var item in args)
{
Console.WriteLine(item);
if (item.Contains("COM"))
{
comPortStr = args[argindex];
}
argindex++;
}
string build_path = args[0];
string projectName = args[args.Length - 1];
projectName = projectName.Substring(0, projectName.Length - 4); //remove extension
build_path = build_path.Replace("\"", string.Empty).Trim();
string hexfilename = build_path + "\\" + projectName + ".hex";
Console.WriteLine("path = {0}", build_path);
Console.WriteLine("comport = {0}", comPortStr);
Console.WriteLine("build name = {0}", projectName);
Console.WriteLine("path to HEX file = {0}", hexfilename);
try
{
Stopwatch stopwatch = Stopwatch.StartNew();
string[] lines = System.IO.File.ReadAllLines(hexfilename);
foreach (string item in lines)
{
Console.WriteLine(item);
}
Console.WriteLine("this took " + stopwatch.ElapsedMilliseconds + " Msec");
}
catch (Exception)
{
throw;
}
Console.WriteLine("Opening Serial Port...");
try
{
SerialPort _serport = new SerialPort(comPortStr, 115200);
_serport.WriteTimeout = 1000;
_serport.WriteBufferSize = 20480;
_serport.Open();
_serport.DiscardOutBuffer();
_serport.DiscardInBuffer();
Thread.Sleep(100);
Console.WriteLine("Sending Trigger Character " + startCmdStr);
Console.WriteLine(startCmdStr);
_serport.Write(startCmdStr);
Console.WriteLine("Waiting for 'waiting' from Teensy...");
rcvStr = string.Empty;
aTimer = new System.Timers.Timer();
//aTimer.Interval = 5000;
aTimer.Interval = 25000;
aTimer.Elapsed += OnTimedEvent;
aTimer.Start();
while (!rcvStr.Contains("waiting") && !bTimedOut)
{
if (_serport.BytesToRead > 0)
{
rcvStr = _serport.ReadLine();
}
}
aTimer.Stop();
if (bTimedOut)
{
Console.WriteLine("Timed out waiting for 'waiting' response from Teensy");
}
else
{
//if we get to here, the Teensy is ready to receive HEX file contents
Console.WriteLine("Received " + rcvStr + " from Teensy");
Stopwatch stopwatch2 = Stopwatch.StartNew();
int numlines = 0;
string[] lines = System.IO.File.ReadAllLines(hexfilename);
foreach (string item in lines)
{
numlines++;
_serport.WriteLine(item);
}
Console.WriteLine("total lines = {0}, time = {1} mSec", numlines, stopwatch2.ElapsedMilliseconds);
//now we wait for Teensy to emit "hex file: xx lines xx bytes..." and then "enter xx to flash..."
aTimer.Start();
while (!rcvStr.Contains("hex file:") && !bTimedOut)
{
if (_serport.BytesToRead > 0)
{
rcvStr = _serport.ReadLine();
}
}
aTimer.Stop();
aTimer.Dispose();
if (bTimedOut)
{
Console.WriteLine("Timed out waiting for 'hex file' response from Teensy");
}
else
{
//extract number of lines from Teensy string, and compare with numlines.
//If they match, then send the number back to Teensy to complete the update.
//Otherwise, send '0' to abort
int colonIdx = rcvStr.IndexOf(':');
int lineIdx = rcvStr.IndexOf("lines");
string compareStr = rcvStr.Substring(colonIdx + 1, lineIdx - colonIdx - 1);
compareStr = compareStr.Trim();
int numTeensyLines = Convert.ToInt16(compareStr);
Console.WriteLine("sent {0} teensy replied {1}", numlines, numTeensyLines);
if (numTeensyLines == numlines)
{
Console.WriteLine("numlines {0} matches numTeensyLines {1} - send confirmation",
numlines, numTeensyLines);
_serport.WriteLine(compareStr);
}
}
}
}
catch (Exception)
{
throw;
}
try
{
}
catch (Exception)
{
throw;
}
}
static string chksum(string input)
{
int TwosComplement(string s)
{
if (s.Length % 2 != 0)
throw new FormatException(nameof(input));
var checksum = 0;
for (var i = 0; i < s.Length; i += 2)
{
var value = int.Parse(s.Substring(i, 2), System.Globalization.NumberStyles.AllowHexSpecifier);
checksum = (checksum + value) & 0xFF;
}
return 256 - checksum & 0xFF;
}
//return string.Concat(":", input, " ", TwosComplement(input).ToString("X2"));
return TwosComplement(input).ToString("X2");
}
private static void SetTimer()
{
// Create a timer with a two second interval.
aTimer = new System.Timers.Timer(2000);
// Hook up the Elapsed event for the timer.
aTimer.Elapsed += OnTimedEvent;
//aTimer.AutoReset = true;
aTimer.Enabled = true;
}
private static void OnTimedEvent(Object source, ElapsedEventArgs e)
{
Console.WriteLine("The Elapsed event was raised at {0:HH:mm:ss.fff}",
e.SignalTime);
bTimedOut = true;
}
}
}
The code that actually does the file transfer is:
Stopwatch stopwatch2 = Stopwatch.StartNew();
int numlines = 0;
string[] lines = System.IO.File.ReadAllLines(hexfilename);
foreach (string item in lines)
{
numlines++;
_serport.WriteLine(item);
}
Console.WriteLine("total lines = {0}, time = {1} mSec", numlines, stopwatch2.ElapsedMilliseconds);
When the '_serport.WriteLine(item);' line is commented out, the reported elapsed time is 0 mSec, as expected - so the 'ReadAllLines()' step isn't the problem.
Anyone have an idea why the 'WriteLine(item)' processing is so slow?

It depends on the structure of the method itself with the device, but I found on the same site an inquiry and means for it that help you
stackoverflow: console writeline slow

How to add a pause between executing tasks in C#

I am currently writing a program which requires me to have a pause between executing tasks.
So I have 4 things.
Read Limit
Delay Between Each Read
Total Reads
Global delay (pause the program for 'x' seconds after a task is finished)
Basically, one task is considered the "Read Limit". So, for example, if I have these settings:
Read Limit (10)
Delay Between Each Read (20)
Total Reads (100)
Global Delay (30)
The program has to read 10 lines from the file based on "Read Limit" and between reading each line, there is a delay of 20 seconds based on "Delay Between Each Read". After it reads 10 lines, it is paused for 30 seconds based on "Global Delay". When the global delay is over, it starts again where it stopped and continues doing this until the limit of 100 is reached based on "Total Reads".
I have tried using System.Threading.Thread.Sleep() but I couldn't make it work. How can I achieve this with C#?
Thanks in advance.
//update with some of my code.
I load the file like this:
private void btnLoadFile_Click(object sender, EventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog();
if (ofd.ShowDialog() == DialogResult.OK)
{
string[] lines = System.IO.File.ReadAllLines(ofd.FileName);
}
}
I have 4 global variables:
public int readLimit = 0;
public int delayBetweenRead = 0;
public int totalReads = 0;
public int globalDelay = 0;
public int linesRead = 0;
And I want to make the function like this:
private void doTask()
{
while (linesRead <= readLimit)
{
readLine(); // read one line
doDelay(); // delay between each line
readLine(); // read another line and so on, until readLimit or totalReads is reached
globalDelay(); // after readLimit is reached, call globalDelay to wait
linesRead++;
}
}

This might be of interest - here's the way to do this with Microsoft's Reactive Framework (NuGet "Rx-Main").
int readLimit = 10;
int delayBetweenRead = 20;
int globalDelay = 30;
int linesRead = 100;
var subscription =
Observable
.Generate(0, n => n < linesRead, n => n + 1, n => n,
n => TimeSpan.FromSeconds(n % readLimit == 0 ? globalDelay : delayBetweenRead))
.Zip(System.IO.File.ReadLines(ofd.FileName), (n, line) => line)
.Subscribe(line =>
{
/* do something with each line */
});
If you need to stop the reading before it finishes naturally just call subscription.Dispose();.

What you do you mean by
I have tried using System.Threading.Thread.Sleep() but I couldn't make it work
Here is an example of achieving what you described with Thread.Sleep:
using (var fs = new FileStream("C:\\test.txt", FileMode.Open, FileAccess.Read))
{
using (var sr = new StreamReader(fs))
{
int nRead = 0;
while (nRead < settings.Total)
{
for (int i = 0; i < settings.ReadLimit && nRead < settings.Total; ++i, nRead++)
{
Console.WriteLine(sr.ReadLine());
if (i + 1 < settings.ReadLimit)
{
Thread.Sleep(settings.Delay * 1000);
}
}
if (nRead < settings.Total)
{
Thread.Sleep(settings.GlobalDelay * 1000);
}
}
}
}

TextBox.Text += "string"; vs TextBox.AppendText("string");

what is the difference between these two methods?
Is one more efficient than the other?
I was thinking maybe the AppendText() uses a method similar to the StringBuilder, ie it uses its own cache instead of creating and appending a new string each time, is that true?
Thanks.

As it is clearly mentioned in Remarks section of MSDN Documentation
The AppendText method enables the user to append text to the contents of a text control without using text concatenation, which, can yield better performance when many concatenations are required.
Your question,
what is the difference between these two methods?
We all know how TextBox.Text += something; will work i.e. creating and appending a new string each time but how AppendText works I could not find any code snippet whether internally it uses StringBuilder or something else.
Is one more efficient than the other?
I think answer to above question will depend on the situation, (Based on Test case observation)
if Multiline property is set to false then Concatenation (+=) yields better results but on other hand Multiline property is set to true then AppendText yields far better performance.
EDIT After reading the comment from Rawling I made a custom win-form solution in which I had a simple textbox in which I appended a simple string hello 10000 times using a simple for-loop
private void btnAppendText_Click(object sender, EventArgs e)
{
txtText.Text = string.Empty;
DateTime startTime = DateTime.Now;
for (int i = 0; i < 10000; i++)
{
txtText.AppendText(s);
}
DateTime endTime = DateTime.Now;
txtTime.Text = (endTime.Ticks - startTime.Ticks).ToString();
}
private void btnConcante_Click(object sender, EventArgs e)
{
txtText.Text = string.Empty;
DateTime startTime = DateTime.Now;
for (int i = 0; i < 5000; i++)
{
txtText.Text += s;
}
DateTime endTime = DateTime.Now;
txtTime.Text = (endTime.Ticks - startTime.Ticks).ToString();
}
Output were very surprising,
TEST 1: Multiline property is true
I had to reduce the iteration to half i.e. 5000 for text concatenation as it was taking a very long time.
btnAppendText_Click output on txtTime was 37222129 almost 3-4 seconds for 10000 iteration
btnConcante_Click output on txtTime was 14449906487 more than 25 minutes for only 5000 iterations.
From the above result it is really clear that, AppendText is much faster and more efficient (when Multiline is true) than Concatenation
TEST 2: Multiline property is false
btnConcante_Click output on txtTime was 39862280 almost 3-4 seconds for 10000 iteration
btnAppendText_Click output on txtTime was 1043279672 almost 2-3 minutes for 10000 iteration
From the above result it is really clear that, Concatenation is faster and more efficient (when Multiline is false) than AppendText

The AppendText has nothing to do with StringBuilder. The Text method actually seems simpler (an possibly more performant). See source code of those two methods for reference:
public void AppendText(string text)
{
if (text.Length > 0)
{
int start;
int length;
this.GetSelectionStartAndLength(out start, out length);
try
{
int endPosition = this.GetEndPosition();
this.SelectInternal(endPosition, endPosition, endPosition);
this.SelectedText = text;
}
finally
{
if (base.Width == 0 || base.Height == 0)
{
this.Select(start, length);
}
}
}
}
public override string Text {
get {
return base.Text;
}
set {
if (value != base.Text) {
base.Text = value;
if (base.IsHandleCreated) {
base.SendMessage(185, 0, 0);
}
}
}
}

As a complement to dbw (and in case someone can find where I've made a mistake), here's my performance test:
private void Form1_Click(object sender, EventArgs e)
{
Stopwatch sw = new Stopwatch();
sw.Reset();
textBox1.Text = "";
sw.Start();
for (int i = 0; i < 10000; i++)
{
textBox1.Text += s;
}
sw.Stop();
var e1 = sw.Elapsed;
sw.Reset();
textBox1.Text = "";
sw.Start();
for (int i = 0; i < 10000; i++)
{
textBox1.AppendText(s);
}
sw.Stop();
var e2 = sw.Elapsed;
}
I see e1 with about 3 seconds and e2 with about 2 minutes.

Why array behaves different when different thread access it

I need to parse large text that is similar to XML. Because the text it is not in memory ( I have a StreamReader object) placing that stream on memory is where I take the most time. So on one thread I place that stream into an array (memory). And I have another thread that process that array. But I am having wierd behavieours. For example take a look at this image:
Note that listToProcess[counter] = buffer and right now that should be listToProcess[10] = buffer Note that the debugger says that listToProcess[10]=null why!? . the other thread just reads the items it does not modify them. At first I thought that maybe the other thread was making that item = null but that is not the case. why am I experiencing this behavior?
In case you want to see my code here it is:
Semaphore sem = new Semaphore(0, 1000000);
bool w;
bool done = false;
// this task is responsible for parsing text created by main thread. Main thread
// reads text from the stream and places chunks in listToProces[]
var task1 = Task.Factory.StartNew(() =>
{
sem.WaitOne(); // wait so there are items on list (listToProcess) to work with
// counter to identify which chunk of char[] in listToProcess we are ading to the dictionary
int indexOnList = 0;
while (true)
{
if (listToProcess[indexOnList] == null)
{
if (done)
break;
w = true;
sem.WaitOne();
w = false;
if (done)
break;
if (listToProcess[indexOnList] == null)
{
throw new NotFiniteNumberException();
}
}
// add chunk to dictionary
ProcessChunk(listToProcess[indexOnList]);
indexOnList++;
}
}); // close task1
bool releaseSem = false;
// this main thread is responsible for placing the streamreader into chunks of char[] so that
// task1 can start processing those chunks
int counter = 0;
while (true)
{
char[] buffer = new char[2048];
// unparsedDebugInfo is a streamReader object
var charsRead = unparsedDebugInfo.Read(buffer, 0, buffer.Length);
if (charsRead < 1)
{
listToProcess[counter] = pattern;
break;
}
listToProcess[counter] = buffer;
counter++;
if (releaseSem)
{
sem.Release();
releaseSem = false;
}
if (counter == 10 || w)
{
releaseSem = true;
}
}
done = true;
sem.Release();
task1.Wait();
Edit
Sorry in other words why do I hit this break point:
I thought that counter was the problem but maybe I am doing something wrong with the semaphore...

You have a counter++ so the one you updated before that was at index 9, not index 10.
Meaning : your claim that it set
listToProcess[10] = buffer:
Is incorrect: it set
listToProcess[9] = buffer: