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  • How to receive packets on the MCU's serial port?

    - by itisravi
    Hello, Consider this code running on my microcontroller unit(MCU): while(1){ do_stuff; if(packet_from_PC) send_data_via_gpio(new_packet); //send via general purpose i/o pins else send_data_via_gpio(default_packet); do_other_stuff; } The MCU is also interfaced to a PC via a UART.Whenever the PC sends data to the MCU, the *new_packet* is sent, otherwise the *default_packet* is sent.Each packet can be 5 or more bytes with a pre defined packet structure. My question is: 1.Should i receive the entire packet from PC using inside the UART interrut service routine (ISR)? In this case, i have to implement a state machine inside the ISR to assemble the packet (which can be lengthy with if-else or switch-case blocks). 2.Detect a REQUEST command (one byte)from the PC in my ISR set a flag, diable UART interrupt alone and form the packet in my while(1) loop by polling the UART?

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  • Function Composition in C++

    - by Channel72
    There are a lot of impressive Boost libraries such as Boost.Lambda or Boost.Phoenix which go a long way towards making C++ into a truly functional language. But is there a straightforward way to create a composite function from any 2 or more arbitrary functions or functors? If I have: int f(int x) and int g(int x), I want to do something like f . g which would statically generate a new function object equivalent to f(g(x)). This seems to be possible through various techniques, such as those discussed here. Certainly, you can chain calls to boost::lambda::bind to create a composite functor. But is there anything in Boost which easily allows you to take any 2 or more functions or function objects and combine them to create a single composite functor, similar to how you would do it in a language like Haskell?

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  • help, stuck with logic variable comparison loop, javascript

    - by Jamex
    I have an input text box for search of input, the id of the text box is: id="search". if a user enters 'cat' at first and hit search. In the function, I get the value 'cat' by using the syntax: var input = document.getElementById("search").value; After that, the user enter 'dog' in the search box and hit search using the same function. The function would assign 'dog' to the input variable. How would I compare the current value (dog) to the previously entered value (cat)? I have tried to assign the original input with a statement, something like var orig = input; but that would only overwrite the original input with the new input. What is the logical approach to this problem.

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  • Is there a good reason Uni courses still use "academic" languages like modula2?

    - by Cheeso
    This question prompts me to ask - why do universities still teach in languages like Modula2, when improved modern languages are available for free? Are there uni's that still teach Pascal, for example? I mean, it was good 30 years ago, but... now? Why? Why not Java, C#, Haskell? Related: Is it backwards to still teach LISP? Is this a duplicate question? If not, I think it ought to be a community wiki topic.

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  • checking whether 4 points in a plane define a square ??

    - by osabri
    how to check whether 4 points in the plane define a square? what's the function which given a point and a value of the area of a square as input parameters returns four squares(define a corresponding type) with sides parallel to the x axis and y axis this how i start: #include <stdio.h> #include<math.h> struct point{ float x; float y; } typedef struct point POINT; struct square{ struct point p1; struct point p2; struct point p3; struct point p4; } typedef struct square SQUARE; int main() { int point; printf("point coordinate"); printf("\n\n"); printf("enter data\n");

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  • how does Cocoa compare to Microsoft, Qt?

    - by Paperflyer
    I have done a few months of development with Qt (built GUI programatically only) and am now starting to work with Cocoa. I have to say, I love Cocoa. A lot of the things that seemed hard in Qt are easy with Cocoa. Obj-C seems to be far less complex than C++. This is probably just me, so: Ho do you feel about this? How does Cocoa compare to WPF (is that the right framework?) to Qt? How does Obj-C compare to C# to C++? How does XCode/Interface Builder compare to Visual Studio to Qt Creator? How do the Documentations compare? For example, I find Cocoa's Outlets/Actions far more useful than Qt's Signals and Slots because they actually seem to cover most GUI interactions while I had to work around Signals/Slots half the time. (Did I just use them wrong?) Also, the standard templates of XCode give me copy/paste, undo/redo, save/open and a lot of other stuff practically for free while these were rather complex tasks in Qt. Please only answer if you have actual knowledge of at least two of these development environments/frameworks/languages.

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  • Problem with .release behavior in file_operations

    - by Yannick
    Hello, I'm dealing with a problem in a kernel module that get data from userspace using a /proc entry. I set open/write/release entries for my own defined /proc entry, and manage well to use it to get data from userspace. I handle errors in open/write functions well, and they are visible to user as open/fopen or write/fwrite/fprintf errors. But some of the errors can only be checked at close (because it's the time all the data is available). In these cases I return something different than 0, which I supposed to be in some way the value 'close' or 'fclose' will return to user. But whatever the value I return my close behave like if all is fine. To be sure I replaced all the release() code by a simple 'return(-1);' and wrote a program that open/write/close the /proc entry, and prints the close return value (and the errno). It always return '0' whatever the value I give. Behavior is the same with 'fclose', or by using shell mechanism (echo "..." /proc/my/entry). Any clue about this strange behavior that is not the one claimed in many tutorials I found? BTW I'm using RHEL5 kernel (2.6.18, redhat modified), on a 64bit system. Thanks. Regards, Yannick

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  • Can someone who understands C code help me understand this code?

    - by Benjamin
    INT GetTree (HWND hWnd, HTREEITEM hItem, HKEY *pRoot, TCHAR *pszKey, INT nMax) { TV_ITEM tvi; TCHAR szName[256]; HTREEITEM hParent; HWND hwndTV = GetDlgItem (hWnd, ID_TREEV); memset (&tvi, 0, sizeof (tvi)); hParent = TreeView_GetParent (hwndTV, hItem); if (hParent) { // Get the parent of the parent of the... GetTree (hWnd, hParent, pRoot, pszKey, nMax); // Get the name of the item. tvi.mask = TVIF_TEXT; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); TreeView_GetItem (hwndTV, &tvi); //send the TVM_GETITEM message? lstrcat (pszKey, TEXT ("\\")); lstrcat (pszKey, szName); } else { *pszKey = TEXT ('\0'); szName[0] = TEXT ('\0'); // Get the name of the item. tvi.mask = TVIF_TEXT | TVIF_PARAM; tvi.hItem = hItem; tvi.pszText = szName; tvi.cchTextMax = dim(szName); if (TreeView_GetItem (hwndTV, &tvi)) //*pRoot = (HTREEITEM)tvi.lParam; //original hItem = (HTREEITEM)tvi.lParam; else { INT rc = GetLastError(); } } return 0; } The block of code that begins with the comment "Get the name of the item" does not make sense to me. If you are getting the listview item why does the code set the parameters of the item being retrieved, because if you already had the values there would be no need to retrieve them. Secondly near the comment "original" is the original line of code which will compile with a varning under embedded visual c++, but if you copy the exact same code into visual studio 2008 it will not compile. Since I did not write any of this code and am trying to learn is it possible the original author made a mistake on this line, since the *pRoot should point to and HKEY type yet he is casting to an HTREEITEM type which should never work since the data types don't match? (Side note someone with a better reputation should add a windows ce tag to SO since windows mobile is not the same as windows ce.)

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  • how to divide a window in openGL?

    - by tsubasa
    I want to divide the window into 2 parts. Each part I can draw a different thing. How can I do that in openGL ? (Actually, my problem is I already drawn a picture on the window. Now I want to get some "space" out of it so I can draw something else. The original picture already took the whole window). I appreciate if anybody could help. Thanks.

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  • I have to make a simple app that connects devices in a network, but I have no idea of how to this

    - by Gabriel Casado
    I want to write an App for android that has only one ListView. The App will constantly search for anything (mobile devices, desktops, etc.) that is connected in the wifi network. The problem is, I have no idea how to do this. What do I need to study? I comprehend I'd need to use a Thread or a Runnable to constantly search for those devices. Also I know very little about TCP, UDP or any internet protocols. So, can someone give me a basis of what I need to learn to develop this App?

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  • Writing Java code in Matlab?

    - by scooziexp
    Hi, I'm trying to use the Java commands pw.println() and br.readLine() in Matlab because I have set up a socket (input_socket2) between Matlab and a command-line program I want to control using Java classes BufferedReader and PrintWriter. Before the following snippet of code, I implemented another socket that goes between 2 computers. This works great and I also know that the following snippet of code successfully opens up a communication line between Matlab and the other program. However, Matlab throws an error at pw.println('noop'). I think it has something to do with syntax, but I'm not sure how to write the command in Matlab syntax then: try input_socket2 = Socket(host2,port2); input_stream2 = input_socket2.getInputStream; d_input_stream2 = DataInputStream(input_stream2); br = BufferedReader(InputStreamReader(input_stream2)); pw = PrintWriter(input_socket2.getOutputStream,true); pw.println('noop') br.read end Any ideas?

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  • Do you think the AI industry will ever come back?

    - by Isaiah
    I just spent some time reading about the collapse of the AI industry and realized a lot of the reason it failed was because technology was slow to catch up with their theories on when it would be available. I also read that it is believed computers that will be able to emulate human synapses may be made round 2015-2025. It's 2010 now and were getting pretty close to that time frame. I was wondering if anyone thinks that the AI industry will return as the technology lands? And if so, will it change the language market? Could Lisp like languages suddenly experience a burst of growth if it does? Idk I just thought it was interesting thinking about it.

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  • Virtual audio driver (microphone)

    - by Dalamber
    Hello guys, I want to develop a virtual microphone driver. Please, do not say anything about DirectShow - that's not "the way". I need a solution that will work with any software including Skype and MSN. And DirectShow doesn't fit these requirements. I found AVStream Filter-Centric Simulated Capture Driver (avssamp.sys) in Windows 7 WDK. What I need is an audio part of it. By default it reads avssamp.wav and plays it. But this driver is registered as WDM streaming capture device. And I want it in Audio Capture Device. There are some posts in the web but they are all the same: http://www.tech-archive.net/Archive/Development/microsoft.public.development.device.drivers/2005-05/msg00124.html http://www.winvistatips.com/problem-installing-avssamp-audio-capture-sources-category-t184898.html I think registering this filter-driver as audio capture device will make Skype recognize it as a microphone and thefore I will be able to push any PCM file as if it goes from mic. If someone already faced this problem before, please help. Thanks in advance.

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  • Problem with pattern matching in ocaml

    - by Antony
    I wrote the function used to decompose a Boolean function, the problem is that the compilation I get this : "Warning 5: this function application is partial, maybe some arguments are missing." How can I solve this problem? I've set wrong the patter matching or I can not run this operation with pattern matching The code is the following: let rec decomposition state_init state prec formula = match formula with And form -> (fun () -> let f1 = List.hd form in let f2 = And(List.tl form )in let new_state = Forms (state_init,f1) in decomposition state_init new_state state f1; decomposition state_init new_state state f2; Hashtbl.add graph new_state (("",false,state :: []) , []) ; let x = Hashtbl.find graph state in let succ = state :: snd x in let (desc,last,ptrs) = fst x in Hashtbl.replace graph state ( ("And-node",last,ptrs) , succ))

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  • warcraft3 packet infromation [closed]

    - by ajay009ajay
    Hello All, I have made a program which is fetching data from server to and game to server. I want to keep these record in my file. But my problem is this is not in good format that i can read easily. I am reading all data as "Byte" (from java). Can anybody explain header or data info of packet. so I can read it in human manner Huh thanks.

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