A quick web search on the phrase “Windows API LARGE_INTEGER” tells us that it “Represents a 64-bit signed integer value”. If we use this declaration as it is, VBA will give us a compile error: “User-defined type not defined”. Notice that the arguments to both Windows APIs have the data type LARGE_INTEGER. "QueryPerformanceFrequency" (lpFrequency As LARGE_INTEGER) As Long What is this LARGE_INTEGER ? "QueryPerformanceCounter" (lpPerformanceCount As LARGE_INTEGER) As Longĭeclare PtrSafe Function QueryPerformanceFrequency Lib "kernel32" Alias _ A quick search for “ QueryPerformanceFrequency” and “ QueryPerformanceCounter” in the text file “ Win32API_PtrSafe.TXT” which is the list of Windows API function declarations for VBA yielded this: ' Performance counter API'sĭeclare PtrSafe Function QueryPerformanceCounter Lib "kernel32" Alias _ In a previous article I described how this is done (you might want to go read that before continuing on here). Step 2: How to Use a Windows API Function within Excel VBA So to measure time with milliseconds accuracy, we calculate this formula: (“End Performance Counter” – “Start Performance Counter” ) / Performance Frequency. Excellent! So we can use two Win32 APIs QueryPerformanceFrequencyfunction to express the frequency (in counts per second) and the QueryPerformanceCounter function to retrieve the current value of the high-resolution performance counter. However, looking at native VBA and Excel time related functions they only provide up to seconds accuracy.Ī web search on “timers using Windows API” eventually lead to this documentation on high resolution timers in Win32 APIs. Ideally this timer should be able to measure up to millisecond resolutions. Our motivations to create a millisecond timers is to allow us to measure the execution time for a piece of VBA code. In this tutorial, not only I will show the complete VBA codes that you can simply copy and use, I will describe the research process involved to create millisecond timers in VBA using Windows APIs so that you can deepen your understanding of using Windows APIs with VBA coding. There are numerous sites that provide sample VBA codes for creating millisecond resolution timers. I didn’t want to just straight up give you all the code, but if you still can’t figure out how to set one up from the hints I have given, let me know and I will paste in my example of a countdown timer, as I have a basic working countdown timer figured out, and I will check on this thread throughout the day to see if you get it working.Step 1: Search for the Right Windows API to solve a problem You will need another variable to hold the value you are starting your countdown from as well. Also, since you are more than likely displaying your counter on a UILabel, you will have to format the time to a String that has the look you want. To end an instance of *Timer*, you can use the *invalidate()* method from the class. One parameter of *scheduledTimer* takes a selector, where you will select the method(a separate function that you create) to update your time. Timer has a function called *scheduledTimer* that you will use to initialize your countdownTimer. You will need to use the *Timer* class(it’s included in an import of UIKit), to create your countdownTimer variable.
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