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GregFreeman

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GregFreeman last won the day on April 19 2018

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About GregFreeman

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  • Birthday 09/13/1986

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    LabVIEW 2013
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    2008

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  1. Very helpful, now it's working. Another big problem I realized is that I had the CLFN set to WINAPI, not C, calling convention 🤦‍♂️
  2. Ah, that makes sense. Needs to be a pointer to the handle... I am not currently crashing mid-function anymore, but i do crash when it reaches the end. I have attached the code as it stands now. I'm creating a linked list myself since I don't have access to the hardware. I am seeing something strange in the visual studio debugger. Notice the value of the str variable in hdl has some junk after "efgh." It's making me think something in the resize and MoveBlock aren't quite right, but I can't figure out what. int EXPORT_API iir_get_serial_numbers(LStrArrayHandle *arr) { MgErr err = mgNoErr; IIR_USB_RELAY_DEVICE_INFO_T* ptr = NULL; IIR_USB_RELAY_DEVICE_INFO_T* deviceInfo = NULL; IIR_USB_RELAY_DEVICE_INFO_T *prev = NULL; LStrHandle *pH = NULL; const char* sn[] = { "abcd", "efgh", "ijkl" }; int len, i = 0, n = (*arr) ? (**arr)->cnt : 0; for (int j = 0;j < 3;++j) { IIR_USB_RELAY_DEVICE_INFO_T* info = (IIR_USB_RELAY_DEVICE_INFO_T*)malloc(sizeof(IIR_USB_RELAY_DEVICE_INFO_T)); info->serial_number = (unsigned char*)malloc(5*sizeof(unsigned char*)); strcpy_s(info->serial_number,5*sizeof(unsigned char*),sn[j]); info->next = NULL; if (!deviceInfo) { deviceInfo = info; } else { prev->next = info; } prev = info; } //IIR_USB_RELAY_DEVICE_INFO_T* deviceInfo = (IIR_USB_RELAY_DEVICE_INFO_T*)iir_usb_relay_device_enumerate(); /* This only works reliably if there is guaranteed that the deviceInfo linked list won't change in the background while we are in this function! */ for (ptr = deviceInfo; ptr; ptr = ptr->next, i++) { /* Resize the array handle only in power of 2 intervals to reduce the potential overhead for resizing and reallocating the array buffer every time! */ if (i >= n) { if (n) n = n << 1; else n = 8; err = NumericArrayResize(uPtr, 1, (UHandle*)arr, n); if (err) break; } len = strlen(ptr->serial_number); pH = (**arr)->elm + i; err = NumericArrayResize(uB, 1, (UHandle*)pH, len); if (!err) { MoveBlock(ptr->serial_number, LStrBuf(**pH), len); LStrLen(**pH) = len; } else break; } if (deviceInfo) { IIR_USB_RELAY_DEVICE_INFO_T *t; while (deviceInfo != NULL) { t = deviceInfo; deviceInfo = deviceInfo->next; free(t); } } /* If we did not find any device AND the incoming array was empty it may be NULL as this is the canonical empty array value in LabVIEW. So check that we have not such a canonical empty array before trying to do anything with it! It is valid to return a valid array handle with the count value set to 0 to indicate an empty array!*/ if (*arr) { /* If the incoming array was bigger than the new one, make sure to deallocate superfluous strings in the array! This may look superstitious but is a very valid possibility as LabVIEW may decide to reuse the array from a previous call to this function in a any Call Library Node instance! */ n = (**arr)->cnt; for (pH = (**arr)->elm + (n - 1); n > i; n--, pH--) { if (*pH) { DSDisposeHandle(*pH); *pH = NULL; } } (**arr)->cnt = i + 1; char buf[1024]; LStrHandle hdl; for (int k = 0; k < ((**arr)->cnt);++k) { hdl = (**arr)->elm[k]; } } //iir_usb_relay_device_free_enumerate(deviceInfo); return err; }
  3. Actually, I did this yesterday to try and figure out the datatypes 😂. I thought some other magic was happening but I suppose not. I guess my question then becomes, why do we choose the particular sizes for uPtr, and how does that translate to our struct size? I suppose I'm just not understanding the relation between uPtr, the cast of arr to UHandle, and 'n' in terms of what is being done inside that resize function. Anyways, unfortunately I keep crashing here: err = NumericArrayResize(uB, 1, (UHandle*)pH, len); I did get a compiler error here: pH = (**strArr)->elm + i; I assume it should be (*strArr) -> elm + i; but I'm not certain. I did change it to this however to get it to compile I have confirmed my variable 'len' = 4 for my serial_number 'abcd' Other than that, I'm not sure what the problem may be. Do we need to include the \0 in the len? I believe doing (UHandle*)(&pH) gets us closer?
  4. Looking at the API, I believe this is the case. @Rolf Kalbermatter would you mind explaining what is happening with the first NumericArrayResize? The one for the string buffer is pretty self explanatory, but I don't quite understand how the first one that resizes the LStrArrayHandle works. How does the function know how to resize memory for a data structure that we have defined ourselves?
  5. Very helpful, both of you. Thanks! Rolf, you mention this will only work if the linked list doesn't change in the background, which of course makes sense. Theoretically it won't change, but it is coming from another API, so I assume there is no way to handle keeping this safe? Even if I were to loop through the linked list immediately and make copies of the items and/or serial numbers, during my looping there is still the risk it could change, correct?
  6. Thanks very much. This is really helpful and makes a lot of sense. My only follow up question is, is it necessary to size the LStrHandle to fit the string and use strcpy? Or can I just assign h -> str to point at the address of s_deviceInfo -> serial_number?
  7. I have a DLL for a device which holds a linked list of structs. Obviously I cannot pass this to LabVIEW, but all I really need are the serial numbers from within the struct. So my idea is to write a wrapper to map the serial numbers to a string array and return them from a dll. Due to my lack of experience with C and lack of examples with the LabVIEW memory manager dll, I'm having quite a hard time. Because the linked list can be of a dynamic length, I am not sure how to handle the memory allocation. This is my attempt so far. My questions are 1) How do I properly size DSNewHandle to fit the serial number, or is there no need to since it's a pointer which will just be set equal to the address of s_deviceInfo -> serialNumber 2) how do I assign each new 'h' to 'arr' 3) since the number of devices/serial numbers can vary, can I still manage this on the LabVIEW side by passing in an empty array constant as 'arr' to the dll? Or do I need to modify how I'm doing things? typedef struct { int32 len; LStrHandle str[]; } **LStrArrayHandle; int iir_get_serial_numbers(LStrArrayHandle arr) { int i = 0; while(s_deviceInfo -> next) { LStrHandle h = (LStrHandle)DSNewHandle(sizeof(LStrHandle)); (*h) -> cnt = strlen(s_deviceInfo -> serial_number); (*h) -> str = s_deviceInfo -> serial_number; } return 0; }
  8. Nope, we have explicit, static registrations for controls in our subpanels. Nothing dynamic or using references. We did potentially trace things back to our error logger. We have a subVI that just throws errors in a queue and then a process that flushes the queue every few seconds and logs them. Seems when we aren't logging errors the problem goes away, so I'm not really sure what's going on. Possibly something there blocking our UI thread somehow and events getting missed but the flush and write happens within 100 ms so it definitely still seems a bit strange. Right now it seems the problem may not be happening in the executable and FWIW we are also updating a good amount of controls by reference with defer panel updates set to true. But the VI Analyzer shows this only taking ~50 ms so I'm not convinced that's the issue either.
  9. I have an application that is using subpanels, and I am having some issues where they seem to be missing button clicks. This is sporadic and not isolated to one specific button but seems to happen throughout the application on various screens. I look in the event inspector window and the value change never fires when these events are missed, so it's as if whatever is managing these events is missing it completely. After two or three clicks it will take. I know it's tough to help without a reproducible case, so I am mostly posting this to see if others have run into this behavior because I have been spinning my wheels.
  10. Thanks very much everyone. And I really appreciate the UML -- very helpful
  11. Sorry for the ambiguous title...hard to convey the problem without description. Right now I have an application that takes various measurements, but for now I'm going to focus on current. The issue is that there are many devices that can take current measurements, which our customer will swap out. But they don't necessarily have a parent/child relationship. Everything I think of screams to me "This would be easy with interfaces" but I'm really hoping there is some solution with composition. The application has a lot of situations where there is a power supply, but they may use a DVM to take the current measurement because they get better resolution on their results. There are other times they just use the current measurement the power supply reports. So, I thought about having a current measurement class that is composed of a "Source" object and a "Measurement" object. In some cases the Source and Measurement objects would both be a power supply. In other cases one may be a power supply and the other a DVM. But, I also want all my power supplies to inherit from BasePowerSupply and the DVM to inherit from BaseDVM. But if I want to do this and have either a power supply or a DVM be the measurement class, they both have to inherit from the same base class with a MeasureCurrent must-override method. However, as soon as I do this, if I want to create a a Source class, the BasePowerSupply can't inherit from it too. To me this just screams having an ICurrentMeasurable interface and an ISourceable interface that classes can implement. But alas, I cannot. So, any suggestions are appreciated. It just seems to me the more complex instruments get the more I really want interfaces to keep overlapping functionality required while avoiding coupling of unrelated devices through inheritance.
  12. For some reason this isn't working for me on Windows 10. Any thoughts? I've installed the latest version and already had the 2016 runtime installed.
  13. SmithD's response seems to be the general consensus I think. Mark, this is a good quote I'm stealing "if more than one class uses a typedef than is belongs to neither " Interesting about the translation classes. Translating the types was actually something I considered, but then I ruled it out because I thought I'd end up with too many types that were essentially duplicates of each other. I'll take a look at his presentation if I can dig it up. I started thinking about other languages such as C# and how they would handle this. I realized most methods would return classes or interfaces, not structures. And I started thinking about why that would be decoupled, and it's because the classes being returned are not owned by any other class. So this gave me my answer. Make sure the typedef isn't owned by any other class, and it effectively just becomes a POCO.
  14. I currently have a project that I am refactoring. There is a lot of coupling that is not sitting well with me due to typedefs belonging to a class, then getting bundled into another class which is then fired off as event data. Effectively, I have class A with a public typedef, then class B contains ClassA.typedef and then class B gets fired off in an event to class C to be handled. Class C now has a dependency on class A which is causing a lot of coupling I don't want. For my real world example I query a bunch of data from our MES, which results in a bunch of typedef controls on the connector panes of those VIs. Those typedefs belong to the MES class. I then want to bundle all that data into a TestConfig class and send that via an event to our Tester class. But, now our tester has a dependency on the MES. I see a few ways to handle this. First is move the typedefs currently in the MES class, to the TestConfig class. The MES VIs will now have the typedefs from the TestConfig class on their connector panes, but at least the dependency is the correct "direction." Or, I can move the typedefs out of classes all together, but then I am not sure the best way to organize them. Looking for how others have handled these sorts of dependencies.
  15. For completeness, this is the c# code where I'm now seeing matching (slow) timing numbers. namespace TestAdodbOpenTime { class Program { static void Main(string[] args) { Stopwatch sw = new Stopwatch(); for (int i = 0; i < 30; i++) { ADODB.Connection cn = new ADODB.Connection(); int count = Environment.TickCount; cn.Open("Provider=OraOLEDB.Oracle;Data Source=DATASOURCE;Extended Properties=PLSQLRSet=1;Pooling=true;", "UID", "PWD", -1); sw.Stop(); cn.Close(); Marshal.ReleaseComObject(cn); int elapsedTime = Environment.TickCount - count; Debug.WriteLine("RunTime " + elapsedTime); } } } } Output: RunTime 218 RunTime 62 RunTime 47 RunTime 31 RunTime 63 ...
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