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Rolf Kalbermatter

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Rolf Kalbermatter last won the day on November 7

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About Rolf Kalbermatter

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    LabVIEW Aficionado
  • Birthday 06/28/1966

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    LabVIEW 2011
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  1. In the case of the libraries that I contributed to OpenG, I tried to add all the names to the copyright notice who provided more than a trivial bug fix. I also happened to add my name to a few VIs in other OpenG packages when I felt it was more than a trivial bug fix.
  2. Well there could be two that apply! "Killing me softly" and "Ready or Not, here I come you can't hide" 😀
  3. The upgraded LLB almost certainly never ever will happen. The lvclassp or whatever it would be called probably neither because you can do that basically today by wrapping one or more lvclasses into a lvlib and then turning that into a lvlibp. While these single file containers are all an interesting feature they have many potential trouble as can be seen with lvlibp. Some are unfortunate and could be fixed with enough effort, others are fundamental problems that are hard to almost impossible to be really done right. Even Microsoft has been basically unable to plugin an archive system like a ZIP archive into its file explorer in a way that feels fully natural and doesn't limit all kind of operations that a user would expect to be able to do in a normal directory. Not saying it's impossible although the Windows Explorer file system extension interface is basically a bunch of different COM interfaces that are both hard to use right and incomplete and limited in various ways. A bit of a bolted on extension with more extensions bolted on on the side whenever the developers found to need a new feature. It works most of the time but even the Microsoft ZIP extension has weird issues from using the COM interfaces in certain ways that were not originally intended. It works good enough to not having to spend more time on it to fix real bugs or to axe the feature and let users rely on external archive viewers like 7-ZIP, but is far from seamless. At least for classic LabVIEW I think the time has come where NI won't spend any time in adding such features anymore. They will limit future improvements to features that can be relatively easily developed for NXP and then backported to classic LabVIEW with little effort. Something like a new file format is not such a thing. It would require a rewrite of substantial parts of the current code and they are pretty much afraid of touching the existing code substantially as it is in large parts very old code with programming paradigms that are completely the opposite to what they use nowadays with classes and other modern C++ programming features. Basically the old code was written with standard C in ways that was meant to fit into the constrained memory of those days with various things that defies modern programming rules completely. Was it wrong? No, it was what was necessary to get it to work on the hardware that was available then, without waiting another 10 years to have on the architecture and hope to get the hardware that makes a modern system able to run, with programming paradigms that were nowhere used at that time.
  4. In general you are working here with non released, non documented features in LabVIEW. You should read the Rusty Nails in Attics thread sometimes. Basically LabVIEW has various areas that are like an attic. There exist experimental parts, non finished features and other things in LabVIEW that were never meant for public consumptions, either because they are not finished and tested, an aborted experiment or a quick and dirty hack for a tool required for NI internal use. There are ways to access some of them, and the means to it have been published many times. NI does not forbid anyone to use them although they do not advertize it. Their stance with them is: If you want to use it, then do but don't come to us screaming because you stepped on a rusty nail in that attic! The fact that the node has a dirty brown header is one indication that it is a dirty feature.
  5. I would say the error message is very clear! The desired call is not supported in the current LabVIEW version. Why do you think this should work?
  6. Hmmm, maybe LabVIEW learned as some point to do that cast if you pass a file refnum to the pointer sized integer input on a Call Library Node. Never tried that!
  7. Yep I know! Linux is a fileID, except there are at least two different types of identifiers, one is a socket like one and one is a posix file IO one. Mac is nasty. For 32 bit it seemed to be a Carbon API FS number, later changed to the posix file IO number for 64 bit. Not sure they changed anything for 32 bit too. The differences and uncertainities make it not a safe bet to just ASSume things and HOPE it will always remain like this, sorry. But nooooo, a file refnum is NOT a Windows file handle. Pease repeat after me: IT IS NOT!. You need the file manager function FRefNumToFD() to retrieve the underlaying file descriptor handle. The File primitives do quite a bit more than just calling the according Windows API function. A lot sits in the path resolution where thinks like shortcuts will autmatically be resolved. It won't do anything special about symlinks and all the Windows APIs except the CreateHandle() with special flags and GetFileAttributes() are made by Microsoft explicitely to work in the way to not do special things with symlinks in the name of maximum backwards compatibility. You need to call special functions to deal with symlinks and some are still not available officially such as reading the target of a symlink explicitly.
  8. It's called bindings to non native libraries and functionality. It's a standard problem in every programming environment. The perceived difficulty has always a direct relation with the distance of the programming paradigme of the calling environment to the callee. In C it is almost non existent, since you have to bother about memory management, thread management, etc, etc. no matter what you try to call. In higher level languages with a managed environmen like LabVIEW or .Net, it seems a lot more complicated. It isn't really but the difference between what you normally have to do in the calling environment is much bigger when calling such non native entities. And each environment has of course a few special subtleties. The one currently causing me a lot of extra work for the OpenG ZIP library is the fact that LabVIEW always has and still does assume that STRING==BYTEARRAY and that encoding does not exist in a LabVIEW platform. A ZIP file can contain encoding in the stored file names and nowadays regularly does. So the strings that are returned as filenames in an archive need to be treated with care. Except when I then try to turn it into a LabVIEW path to create the file, the whole care falls into the water as the filepath either will alter the name to something else or even possibly attempt to create a file with invalid characters. So the solution is to replace the Open File, Create File and Create Directory among with some others functions (like Delete File) with my own version that can handle the paths properly. Great idea except that LabVIEW does not document and hence not guarantee how the underlaying file system object is mapped into a file refnum. So in order to be safe here I also have to create the Read File, Write File, Close File, File Size and such functions.All doable but serious work to do. I'm basically rewriting the LabVIEW File Manager and Path Manager functionality for a considerable amount.
  9. Sssssht! My first version was without that sequence structure and I was for a brief moment wondering if maybe my ability to do the pointer juggling had failed me. After looking over it once more I figured the problem must be elsewhere and then it struck me that the control assignment was happening right after the NumericArrayResize() call. LabVIEW has a preference to do terminal assignments always as soon as possible.
  10. That's just to force execution of the copying of the array size before assigning the handle to the control. Looks strange when you have created an array with elements but the control shows an empty array. For use as subVI it wouldn't really matter as by the time the subVI returns the array it is correctly sized but when you test run it from the front panel it looks weird.
  11. Would work but has the same problem of having to set the array length too, so you save nothing except that you use DSSetHandleSize() instead of NumericArrayResize() (and need to do some extra calculations as you also have to account for the extra int32 that is in there.
  12. Well it is when you look at how the equivalent looks in C 😄 MgErr AllocateArray(LStrHandle *pHandle, size_t size) { MgErr err = NumericArrayResize(uB, 1, (UHandle*)pHandle, size); if (size && !err) LStrLen(**pHandle) = (int32)size; return err; } Very simple! The complexity comes from what in C is that easy LStrLen() macro, which does some pointer vodoo that is tricky to resemble in LabVIEW.
  13. That's probably why I gave up on C++ years ago already. If I have to program something that requires anything on low level, I prefer simple old standard C. Sure nobody will build a software like LabVIEW in C anymore but that is not my target anyways.
  14. That was my first thought too 😆. But!!!! The Call Library Node only allows for Void, Numeric and String return types and the String is restricted to C String Pointer and Pascal String Pointer. The String Handle type is not selectable. -> Bummer! And the logic with the two MoveBlock functions to tell the array in the handle what size it actually has, needs to be done anyway. Otherways the handle might be resized automatically by LabVIEW at various places when passing through Array nodes for instance, such as the Replace Array Subset node. Also Replace Array Subset would not copy data into an array beyond the indicated array size too. Handle size and array size are not strictly coupled beyond the obvious requirement handle size >= dimensions * sizeof(int32) + array size * array element size
  15. Nope, sorry. Still, trying to get information if a memory allocation might succeed by looking at whatever memory statistics might be available can never be a foolproof approach. It has the classical race that between checking if you can and doing it, the statistics might be not actual anymore and you still fail. The only fool proof approach is to actually do the allocation and deal with the failure of it. Of course for memory allocations that is always tricky as seen here. We want to read in a 900MB file and want to be sure we can read it in. Checking if we can and then trying can still fail. We have to allocate the entire buffer beforehand and then copy piece by piece the file into this buffer. Another approach might be a memory mapped file but trying to trick LabVIEW build in functions to use such a beast is an entire exercise in its own. You basically invert the complete execution flow from calling a function that returns some data, to first preparing a buffer and hand it to a function to use it to eventually return that data. If you ever have dealt with streams (in Java, or .Net which has not only taken the whole stream concept verbatim from Java) you will know this problem. It's super handy and normally quite easy but internally quite complex. And you always end up with two distinct types that can't be easily connected without some intermediate proxy, Input Streams and Output Streams. And such a proxy will always involve copying data from one stream to the other, adding significant overhead to the originally very simple and seemingly beautiful idea. Now, one solution in hindsight that would be beneficial in the OPs case would be if those LabVIEW low level functions would return an error 2 or so in these cases rather than throw up a dialog that gives you only the option to quit, crash or puke. With the current almost everywhere present error cluster and its consisten handling throughout LabVIEW, this would seem the logical choice. Back when LabVIEW was invented however, error clusters were not even thought of yet and error handling from things like out of memory conditions was anyhow an end of story condition in almost all cases, since once that happened LabVIEW would almost surely run into other out of memory conditions when trying to handle the previous error conditions. When LabVIEW for Windows came out, most users found 8MB of memory an outragous expensive requirement and were insisting that LabVIEW should be able to fly to the moon and back with the 4MB it was claiming to work with in the marketing material.
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