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The Pros and Cons of Using Gettickcount in Delphi XE5



What is Gettickcount Delphi Xe5 Serial Number and Why You Need It




If you are a Delphi developer, you may have encountered the need to measure the elapsed time between two events or to create a delay or a timeout in your code. For example, you may want to check how long it takes to execute a certain procedure, or to wait for a certain condition to be met before proceeding. One of the simplest and most common ways to do this is to use the Gettickcount function, which is part of the Windows API and available in Delphi XE5.




Gettickcount Delphi Xe5 Serial Number



The Gettickcount function returns the number of milliseconds that have passed since the system was started. It is a 32-bit unsigned integer value that wraps around every 49.7 days. The serial number of the function is the version number of the Delphi compiler that supports it. For example, Gettickcount Delphi Xe5 Serial Number means that the function is supported by Delphi XE5, which has the serial number 19.0.


In this article, we will explain how to use the Gettickcount function in Delphi XE5, what are its benefits and challenges, and what are some alternatives to it. We will also answer some frequently asked questions about the function.


What is Gettickcount Function and How It Works




The Gettickcount function is declared in the Windows unit as follows:


function GetTickCount: DWORD; stdcall;


The function has no parameters and returns a DWORD value, which is an alias for Cardinal, a 32-bit unsigned integer type. The function calls the Windows API function GetTickCount64, which returns a 64-bit value, and truncates it to 32 bits. The function is marked as stdcall, which means that it uses the standard calling convention for Windows API functions.


The function works by reading the value of a system timer that is incremented every millisecond by the system clock. The timer starts at zero when the system is booted and wraps around to zero every 49.7 days (or 2^32 milliseconds). The function returns the current value of the timer, which represents the number of milliseconds that have elapsed since the system was started.


The function is thread-safe, which means that it can be called from multiple threads without causing any conflicts or errors. However, it is not guaranteed to be monotonic, which means that it may not always increase or stay the same over time. This can happen if the system time or clock speed is changed by the user or by another program.


How to Use Gettickcount in Delphi XE5




To use the Gettickcount function in Delphi XE5, you need to add the Windows unit to the uses clause of your unit or program. For example:


uses Windows; Then, you can call the function anywhere in your code where you need to get the current tick count. For example, you can use the function to measure the elapsed time between two events by subtracting the tick count at the start of the event from the tick count at the end of the event. For example:


var Start, Finish, Elapsed: Cardinal; begin Start := GetTickCount; // get the tick count at the start of the event // do something that takes some time Finish := GetTickCount; // get the tick count at the end of the event Elapsed := Finish - Start; // calculate the elapsed time in milliseconds ShowMessage('The event took ' + IntToStr(Elapsed) + ' milliseconds'); // display the result end;


You can also use the function to create a delay or a timeout in your code by using a loop that checks the tick count until a certain amount of time has passed or a certain condition is met. For example, you can use the function to wait for 5 seconds before proceeding with your code. For example:


var Start, Current: Cardinal; begin Start := GetTickCount; // get the tick count at the start of the wait repeat Current := GetTickCount; // get the current tick count Application.ProcessMessages; // process any pending messages until Current - Start >= 5000; // check if 5 seconds have passed // continue with your code end;


How to Create a Wait Using Gettickcount in Delphi XE5




As we have seen in the previous example, you can use the Gettickcount function to create a wait in your code by using a loop that checks the tick count until a certain amount of time has passed. However, this method has some drawbacks, such as:


  • It may block the main thread and prevent it from responding to user input or other events.



  • It may consume CPU resources and affect the performance of your application.



  • It may not be accurate or reliable if the system time or clock speed is changed during the wait.



A better way to create a wait using Gettickcount is to use a separate thread that performs the wait and notifies the main thread when it is done. This way, you can avoid blocking the main thread and allow it to process other messages and events. You can also use a synchronization object, such as an event or a semaphore, to signal when the wait is over. For example, you can use the following code to create a thread that waits for 5 seconds using Gettickcount and then sets an event object:


type TWaitThread = class(TThread) private FEvent: THandle; // handle of an event object FDelay: Cardinal; // delay in milliseconds protected procedure Execute; override; public constructor Create(AEvent: THandle; ADelay: Cardinal); end; constructor TWaitThread.Create(AEvent: THandle; ADelay: Cardinal); begin inherited Create(False); // create a suspended thread FEvent := AEvent; // assign the event handle FDelay := ADelay; // assign the delay value FreeOnTerminate := True; // free the thread when it terminates end; procedure TWaitThread.Execute; var Start, Current: Cardinal; begin Start := GetTickCount; // get the tick count at the start of the wait repeat Current := GetTickCount; // get the current tick count Sleep(10); // sleep for 10 milliseconds to reduce CPU usage until Current - Start >= FDelay; // check if the delay has passed SetEvent(FEvent); // set the event object to signal that the wait is over end;


Then, you can use this thread in your main thread by creating an event object and passing its handle to the thread constructor. You can then use WaitForSingleObject or WaitForMultipleObjects functions to wait for the event object to be signaled. For example:


var Event: THandle; begin Event := CreateEvent(nil, True, False, nil); // create a manual-reset event object that is initially non-signaled try TWaitThread.Create(Event, 5000); // create and start a wait thread that waits for 5 seconds and sets the event object when done WaitForSingleObject(Event, INFINITE); // wait for the event object to be signaled or until the timeout expires // continue with your code finally CloseHandle(Event); // close the event object handle end; end;


This method is more efficient and reliable than using a loop in the main thread, as it does not block the main thread, consumes less CPU resources, and is not affected by system time or clock speed changes.


How to Handle Gettickcount Wrap-around in Delphi XE5




As we have mentioned before, the Gettickcount function returns a 32-bit value that wraps around every 49.7 days. This means that if you use the function to measure the elapsed time between two events, you may get an incorrect result if the wrap-around occurs between the two events. For example, if you use the following code to measure the elapsed time between two events:


var Start, Finish, Elapsed: Cardinal; begin Start := GetTickCount; // get the tick count at the start of the event // do something that takes some time Finish := GetTickCount; // get the tick count at the end of the event Elapsed := Finish - Start; // calculate the elapsed time in milliseconds ShowMessage('The event took ' + IntToStr(Elapsed) + ' milliseconds'); // display the result end;


You may get a negative or very large value for Elapsed if Finish is less than Start due to the wrap-around. For example, if Start is 4294967295 (the maximum value of a 32-bit unsigned integer) and Finish is 0 (the minimum value of a 32-bit unsigned integer), then Elapsed will be -4294967295, which is incorrect.


To handle this situation, you need to use a special technique to compare and subtract two tick count values. The technique is based on the fact that if you subtract two unsigned integers and cast the result to a signed integer, you will get the correct difference regardless of the wrap-around. For example, if you use the following code to compare and subtract two tick count values:


var Start, Finish, Elapsed: Cardinal; begin Start := GetTickCount; // get the tick count at the start of the event // do something that takes some time Finish := GetTickCount; // get the tick count at the end of the event Elapsed := Integer(Finish - Start); // calculate the elapsed time in milliseconds and cast it to a signed integer ShowMessage('The event took ' + IntToStr(Elapsed) + ' milliseconds'); // display the result end;


You will get a positive or zero value for Elapsed even if Finish is less than Start due to the wrap-around. For example, if Start is 4294967295 and Finish is 0, then Elapsed will be 1, which is correct.


This technique works because when you cast an unsigned integer to a signed integer, you preserve its bit pattern but change its interpretation. For example, if you have an unsigned integer with a bit pattern of 11111111111111111111111111111111, which represents 4294967295, and you cast it to a signed integer, you will get a bit pattern of 11111111111111111111111111111111, which represents -1. The difference between these two values is still 1, regardless of how they are interpreted.


This technique is also recommended by Microsoft in their documentation of the Gettickcount function. You can use this technique whenever you need to compare or subtract two tick count values in Delphi XE5.


What are the Benefits of Using Gettickcount in Delphi XE5




The Gettickcount function has some benefits that make it useful for Delphi developers. Some of these benefits are:


High Performance and Accuracy




The Gettickcount function is very fast and lightweight, as it only reads a single value from a system timer. It does not perform any complex calculations or operations that may slow down your code. It also has a high accuracy of one millisecond, which is sufficient for most applications that need to measure short intervals of time.


Cross-platform Compatibility




The Gettickcount function is compatible with all versions of Windows, from Windows XP to Windows 10. It is also compatible with other platforms that support the Windows API, such as Linux and MacOS, through the use of third-party libraries or tools. This means that you can use the function in your Delphi XE5 applications without worrying about the compatibility issues with different operating systems.


Easy Integration with Other Functions and Components




The Gettickcount function is easy to integrate with other functions and components that use the same unit of time, which is milliseconds. For example, you can use the function with the Sleep function, which suspends the execution of the current thread for a specified number of milliseconds. You can also use the function with the TDateTime type, which represents a date and time value in Delphi. You can convert a tick count value to a TDateTime value by dividing it by 86400000 (the number of milliseconds in a day) and adding it to the Date function, which returns the current date. For example:


var Tick: Cardinal; DT: TDateTime; begin Tick := GetTickCount; // get the current tick count DT := Date + Tick / 86400000; // convert it to a TDateTime value ShowMessage('The current date and time is ' + DateTimeToStr(DT)); // display the result end;


This way, you can use the Gettickcount function with other functions and components that deal with date and time values, such as TTimer, TStopwatch, or TFormatSettings.


What are the Challenges of Using Gettickcount in Delphi XE5




The Gettickcount function also has some challenges that may limit its usefulness or cause some problems for Delphi developers. Some of these challenges are:


Potential Blocking of the Main Thread




If you use the Gettickcount function to create a wait or a timeout in your code by using a loop in the main thread, you may block the main thread and prevent it from responding to user input or other events. This may cause your application to appear unresponsive or frozen, and may affect the user experience or functionality of your application. To avoid this, you should use a separate thread or a synchronization object to create a wait or a timeout, as we have shown in the previous examples.


Limited Resolution and Range




The Gettickcount function has a limited resolution and range, which may not be suitable for some applications that require higher precision or longer intervals of time. The resolution of the function is one millisecond, which means that it cannot measure intervals shorter than one millisecond. The range of the function is 49.7 days, which means that it cannot measure intervals longer than 49.7 days. If you need to measure intervals shorter than one millisecond or longer than 49.7 days, you may need to use another function or tool that has a higher resolution or range.


Dependency on System Time and Clock Speed




The Gettickcount function depends on the system time and clock speed, which may not be constant or accurate. The system time and clock speed may be changed by the user or by another program, which may affect the value returned by the function. For example, if the user changes the system time or clock speed while your application is running, the tick count value may jump forward or backward, causing incorrect results or errors in your code. To avoid this, you should not rely on the absolute value of the tick count, but only on its relative value. You should also handle any possible errors or exceptions that may occur due to system time or clock speed changes.


What are the Alternatives to Gettickcount in Delphi XE5




If you find that the Gettickcount function does not meet your needs or expectations, you may want to consider some alternatives to it. Some of these alternatives are:


TTimer Component




The TTimer component is a visual component that allows you to execute code at specified intervals. You can use this component to create timers, delays, timeouts, or periodic tasks in your application. You can set the interval property of the component to specify how often it should fire its OnTimer event, which is where you can write your code. You can also enable or disable the component by setting its enabled property to true or false. The TTimer component is easy to use and does not block the main thread, but it has some limitations, such as:


  • It has a minimum interval of 10 milliseconds, which means that it cannot fire more frequently than that.



  • It is not very accurate or reliable, as it may fire earlier or later than the specified interval due to system load or other factors.



  • It may interfere with other timers or components that use the same message queue.



You can use the TTimer component in Delphi XE5 by adding it to your form or data module from the System tab of the Component Palette. For example, you can use the following code to create a timer that fires every second and displays a message:


procedure TForm1.Timer1Timer(Sender: TObject); begin ShowMessage('The timer fired'); end;


QueryPerformanceCounter Function




The QueryPerformanceCounter function is another Windows API function that allows you to measure the elapsed time between two events with high precision and accuracy. The function returns the current value of a high-resolution performance counter, which is incremented at a constant rate by the system. The function is declared in the Windows unit as follows:


function QueryPerformanceCounter(var lpPerformanceCount: Int64): BOOL; stdcall;


The function has one parameter, which is a variable of type Int64, a 64-bit signed integer type. The function stores the current value of the performance counter in this variable and returns a boolean value indicating whether the function succeeded or failed. The function is marked as stdcall, which means that it uses the standard calling convention for Windows API functions.


The function works by reading the value of a system timer that is incremented at a fixed frequency by the system. The frequency of the timer is determined by the hardware and can be obtained by calling another function, QueryPerformanceFrequency, which returns the number of counts per second. The frequency of the timer is typically in the range of megahertz or gigahertz, which means that it has a very high resolution and accuracy.


The function is thread-safe, which means that it can be called from multiple threads without causing any conflicts or errors. It is also guaranteed to be monotonic, which means that it always increases or stays the same over time. It is not affected by system time or clock speed changes, as it uses a separate hardware timer.


To use the QueryPerformanceCounter function in Delphi XE5, you need to add the Windows unit to the uses clause of your unit or program. For example:


uses Windows; You can use the following code to use the QueryPerformanceCounter function in Delphi XE5:


uses Windows; var Start, Finish, Frequency, Elapsed: Int64; begin QueryPerformanceFrequency(Frequency); // get the frequency of the performance counter QueryPerformanceCounter(Start); // get the value of the performance counter at the start of the event // do something that takes some time QueryPerformanceCounter(Finish); // get the value of the performance counter at the end of the event Elapsed := (Finish - Start) * 1000 div Frequency; // calculate the elapsed time in milliseconds ShowMessage('The event took ' + IntToStr(Elapsed) + ' milliseconds'); // display the result end;


You can use this function to measure the elapsed time between two events with high precision and accuracy, as it has a resolution of nanoseconds and a range of centuries. However, this function also has some limitations, such as:


  • It may not be available on some older or non-standard hardware platforms.



  • It may not be consistent across multiple processors or cores, as they may have different clock speeds or synchronization issues.



It may be affected by power management feat


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