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  • How to get started with embedded systems in the aircraft or submarine industries?

    - by Jason
    Hi, Not 100% sure how to frame this question but here goes... I currently work as a Rails developer but want to work on more substancial / "meaty" projects and have always been very interested in embedded systems, especially systems that run on aircraft and especially submarines.....I know strange combination. I have been doing some searching & found lockheed martin produces a lot of underwater systems for various navys around the world e.g. http://www.naval-technology.com/projects/nssn/ However, there is very little information about what software is used within these systems, what OS's they use or anything else "technical", presume there is a lot of C / C++ involved but that is just a guess... so its hard to know where to even begin learning what is required to potential work in these areas. Just wondering if anyone has any experiance working with or more information about embeddeed systems in either the airline (onboard flight systems) or especially submarine systems? Thanks!

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  • multiple timer to one process (without linking to rt)

    - by Richard
    Hi, is there any way to register multiple timer to a single process? I have tried following code, yet without success. (Use "gcc -lrt" to compile it...). Program output nothing, which should atleast print "test". Is it possibly due to the dependence to linking to rt? #define TT_SIGUSR1 (SIGRTMAX) #define TT_SIGUSR2 (SIGRTMAX - 1) #define TIME_INTERVAL_1 1 #define TIME_INTERVAL_2 2 #include <signal.h> #include <time.h> #include <stdio.h> #include <unistd.h> #include <linux/unistd.h> #include <sys/syscall.h> #include <sys/time.h> #include <sys/types.h> #include <sched.h> #include <signal.h> #include <setjmp.h> #include <errno.h> #include <assert.h> timer_t create_timer(int signo) { timer_t timerid; struct sigevent se; se.sigev_signo = signo; if (timer_create(CLOCK_REALTIME, &se, &timerid) == -1) { fprintf(stderr, "Failed to create timer\n"); exit(-1); } return timerid; } void set_timer(timer_t timerid, int seconds) { struct itimerspec timervals; timervals.it_value.tv_sec = seconds; timervals.it_value.tv_nsec = 0; timervals.it_interval.tv_sec = seconds; timervals.it_interval.tv_nsec = 0; if (timer_settime(timerid, 0, &timervals, NULL) == -1) { fprintf(stderr, "Failed to start timer\n"); exit(-1); } return; } void install_sighandler2(int signo, void(*handler)(int)) { struct sigaction sigact; sigemptyset(&sigact.sa_mask); sigact.sa_flags = SA_SIGINFO; //register the Signal Handler sigact.sa_sigaction = handler; // Set up sigaction to catch signal first timer if (sigaction(signo, &sigact, NULL) == -1) { printf("sigaction failed"); return -1; } } void install_sighandler(int signo, void(*handler)(int)) { sigset_t set; struct sigaction act; /* Setup the handler */ act.sa_handler = handler; act.sa_flags = SA_RESTART; sigaction(signo, &act, 0); /* Unblock the signal */ sigemptyset(&set); sigaddset(&set, signo); sigprocmask(SIG_UNBLOCK, &set, NULL); return; } void signal_handler(int signo) { printf("receiving sig %d", signo); } int main() { printf("test"); timer_t timer1 = create_timer(TT_SIGUSR1); timer_t timer2 = create_timer(TT_SIGUSR2); set_timer(timer1, TIME_INTERVAL_1); set_timer(timer2, TIME_INTERVAL_2); install_sighandler2(TT_SIGUSR1, signal_handler); install_sighandler(TT_SIGUSR2, signal_handler); while (1) ; return 0; }

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  • WP7 - correctly timeing out an observable?

    - by Gaz83
    WP7 APP Using an observable from event, I download the lateset weather from a web service. I tested this out on the phone and emulator at home and it works fine. I brought the project with me to work and ran it using the emulator there. Now i'm not sure it its a firewall or what but it doesn't seem to get the weather, it just sits there for ever trying. So it got me thinking that if there was ever to happen on a phone then I need some kind of timeout in that if it can't get the weather in say 10 - 15 seconds then just give up. Here is the example code so far IObservable<IEvent<MyWeather.GetWeatherCompletedEventArgs>> observable = Observable.FromEvent<MyWeather.GetWeatherCompletedEventArgs>(Global.WeatherService, "MyWeather.GetWeatherCompleted").Take(1); observable.Subscribe(w => { if (w.EventArgs.Error == null) { // Do something with the weather } }); Global.WeatherService.GetWeatherAsync(location); How can I get this to time out safely after a given time if nothing is happening?

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  • How are operating Systems created? Which language is chosen for coding?

    - by Nitesh Panchal
    Hello, How is a basic OS created? In which language do programmers code for OS? C or Assembly? or which? Also, Assembly has limited instruction set like mov etc. So how can anybody create OS in assembly? and even C has limited functionality. But it is said to be the mother of all languages. How can anybody create a full OS with stunning graphics in C? It's simply out of my mind. And what is time duration it takes for a very basic OS to be created? unlike Windows 7 :p

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  • maximum memory which malloc can allocate!

    - by Vikas
    I was trying to figure out how much memory I can malloc to maximum extent on my machine (1 Gb RAM 160 Gb HD Windows platform). I read that maximum memory malloc can allocate is limited to physical memory.(on heap) Also when a program exceeds consumption of memory to a certain level, the computer stops working because other applications do not get enough memory that they require. So to confirm,I wrote a small program in C, int main(){ int *p; while(1){ p=(int *)malloc(4); if(!p)break; } } Hoping that there would be a time when memory allocation will fail and loop will be breaked. But my computer hanged as It was an infinite loop. I waited for about an hour and finally I had to forcely shut down my computer. Some questions: Does malloc allocate memory from HD also? What was the reason for above behaviour? Why didn't loop breaked at any point of time.? Why wasn't there any allocation failure?

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  • CLI design and implementation?

    - by Majid
    I am developing a time management tool for my personal use. I prefer using keyboard over mouse, and on the interface have a general purpose text box which will act like a command line. I have just started thinking about what commands I need, what to use for the command names, how to pass in switches and parameters, and so forth. I wonder if some of you have come across a good read along these lines; something that describes the choices you have for designing a cli, and how those affect the complexity of the interpreter, and extendability of the commands. It makes no difference if the descriptions are language-specific or in general terms. However, my implementation will be with javascript. Thank you.

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  • Counting Sublist Elements in Prolog

    - by idea_
    How can I count nested list elements in prolog? I have the following predicates defined, which will count a nested list as one element: length([ ], 0). length([H|T],N) :- length(T,M), N is M+1. Usage: ?- length([a,b,c],Out). Out = 3 This works, but I would like to count nested elements as well i.e. length([a,b,[c,d,e],f],Output). ?- length([a,b,[c,d,e],f],Output). Output = 6

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  • How to modify Keyboard interrupt (under Windows XP) from a C++ Program ?

    - by rockr90
    Hi everyone ! We have been given a little project (As part of my OS course) to make a Windows program that modifies keyboard input, so that it transforms any lowercase character entered into an uppercase one (without using caps-lock) ! so when you type on the keyboard you'll see what you're typing transformed into uppercase ! I have done this quite easily using Turbo C by calling geninterrupt() and using variables _AH, _AL, i had to read a character using: _AH = 0x07; // Reading a character without echo geninterrupt(0x21); // Dos interrupt Then to transform it into an Upercase letter i have to mask the 5th bit by using: _AL = _AL & 0xDF; // Masking the entered character with 11011111 and then i will display the character using any output routine. Now, this solution will only work under old C DOS compilers. But what we intend to do is to make a close or similar solution to this by using any modern C/C++ compiler under Windows XP ! What i have first thought of is modifying the Keyboard ISR so that it masks the fifth bit of any entered character to turn it uppercase ! But i do not know how exactly to do this. Second, I wanted to create a Win32 console program to either do the same solution (but to no avail) or make a windows-compatible solution, still i do not know which functions to use ! Third I thought to make a windows program that modifies the ISR directly to suit my needs ! and i'm still looking for how to do this ! So please, If you could help me out on this, I would greatly appreciate it ! Thank you in advance ! (I'm using Windows XP on intel X86 with mingw-GCC compiler.)

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  • UsrClass.dat does not load, any ideas on what to check?

    - by Bob Simmons
    I have an odd problem where one of my users' UsrClass.dat hive does not load, which causes .NET ClickOnce applications to fail to start. They are one of several users on a Windows 2000 terminal server, all the others have no problem. Nothing is mentioned in any logs. I can manually load the hive to the correct HKEY_USERS\..._Classes location using REGEDT32, which works around the problem, but I've no idea what could be causing this in the first place. Any ideas what to check here, or any diagnostic tools or procedures that would help?

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  • UsrClass.dat does not load, any ideas on what to check?

    - by Bob Simmons
    I have an odd problem where one of my users' UsrClass.dat hive does not load, which causes .NET ClickOnce applications to fail to start. They are one of several users on a Windows 2000 terminal server, all the others have no problem. Nothing is mentioned in any logs. I can manually load the hive to the correct HKEY_USERS\..._Classes location using REGEDT32, which works around the problem, but I've no idea what could be causing this in the first place. Any ideas what to check here, or any diagnostic tools or procedures that would help?

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  • GPG error occurs while using "deb file:/local-path-to-repo ..." in /etc/apt/sources.list

    - by Chandler.Huang
    I need to install packages within non-internet connection environment. My plan is to download dist structure from Internet and then add file path to /etc/apt/sources.list. So I download related structure includes ubunt/dists/precise, precise-backports, precise-proposed, precise-security, precise-updates from a ftp mirror server. And then I remove original source and add the following to my /etc/apt/sources.list. deb file:path-to-local-ubuntu-directory/ precise main restricted multiverse universe deb-src file:path-to-local-ubuntu-directory/ precise main restricted multiverse universe Then I got GPG error as following after apt-get update. root@openstack:/~# apt-get update Ign file: precise InRelease Get:1 file: precise Release.gpg [198 B] Get:2 file: precise Release [50.1 kB] Ign file: precise Release Get:3 file: precise/main TranslationIndex [3,761 B] Get:4 file: precise/multiverse TranslationIndex [2,716 B] Get:5 file: precise/restricted TranslationIndex [2,636 B] Get:6 file: precise/universe TranslationIndex [2,965 B] Reading package lists... Done W: GPG error: file: precise Release: The following signatures were invalid: BADSIG 0976EAF437D05B5 Ubuntu Archive Automatic Signing Key <[email protected]> I had tried use the following steps after google but in vain. sudo apt-get clean cd /var/lib/apt sudo mv lists lists.old sudo mkdir -p lists/partial sudo apt-get update Is there any way to resolve this? And why this error occurs? Thanks a lot.

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  • How do I invert a colour?

    - by ThePower
    I know that this won't directly invert a colour, it will just 'oppose' it. I was wondering if anyone knew a simple way (a few lines of code) to invert a colour from any given colour? At the moment I have this (which isn't exactly the definition of an invert): const int RGBMAX = 255; Color InvertMeAColour(Color ColourToInvert) { return Color.FromArgb(RGBMAX - ColourToInvert.R, RGBMAX - ColourToInvert.G, RGBMAX - ColourToInvert.B); }

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  • Dedicating all processor power to a task

    - by Yktula
    Let's say we have a very processor-intensive task at hand which could be effectively parallelized. How can we dedicate all or almost all available processor power to performing that task? The task could be a variety of things, and iterative Fibonacci number generation that saves recorded numbers would be just one example.

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  • Check whether a folder is a local or a network resource in .NET

    - by rwmnau
    Is there a quick way to check whether a path I have is on a local disk or somewhere on the network? I can't just check to see if it's a drive letter vs. UNC, because that would incorrectly identify mapped drives as local. I assumed it would be a boolean in the DirectoryInfo object, but it appears that it's not. I've found classic VB code to do this check (through an API), but nothing for .NET so far.

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  • PHP is not returning me a number type

    - by Tristan
    Hello, i tryed to follow that great tutorial (STAR rating with css : http://stackoverflow.com/questions/1987524/turn-a-number-into-star-rating-display-using-jquery-and-css) but i've just a big problem : When i do <span class="stars">1.75</span> or $foo='1.75'; echo '<span class="stars">'.$foo.'</span> the stars is correctly shown, but as soon as i do : while($val = mysql_fetch_array($result)) { $average = ($val['services'] + $val['serviceCli'] + $val['interface'] + $val['qualite'] + $val['rapport'] ) / 5 ; <span class="stars">.$average.</span> } the stars stops working i double checked the data type in mysql : they're all TINYINT(2) and i tryed that : $average = intval($average); but it's still not working, Thank you

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