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  • Work with 64-bit VM in Windows 7

    I attended a Microsoft Office and SharePoint 2010 HOL 1 day workshop last week and wanted to setup a VM to try the new features in my own laptop. The presenter in the workshop implicitly mentioned a tool called VirtualBox (because it's not a MS product?) but I have no clue what it is at that moment. Until today, I saw a very useful blog and thanks to Guy and Rolly. I know what to do next in order to setup the VM in my Windows 7 safely now. :)...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Speed up executable program Linux. Bit Toggling

    - by AK_47
    I have a ZyBo circuit board which has a ArmV7 processor. I wrote a C program to output a clock and a corresponding data sequence on a PMOD. The PMOD has a switching speed of up to 50MHz. However, my program's created clock only has a max frequency of 115 Hz. I need this program to output as fast as possible because the PMOD I'm using is capable of 50MHz. I compiled my program with the following code line: gcc -ofast (c_program) Here is some sample code: #include <stdio.h> #include <stdlib.h> #define ARRAYSIZE 511 //________________________________________ //macro for the SIGNAL PMOD //________________________________________ //DATA //ZYBO Use Pin JE1 #define INIT_SIGNAL system("echo 54 > /sys/class/gpio/export"); system("echo out > /sys/class/gpio/gpio54/direction"); #define SIGNAL_ON system("echo 1 > /sys/class/gpio/gpio54/value"); #define SIGNAL_OFF system("echo 0 > /sys/class/gpio/gpio54/value"); //________________________________________ //macro for the "CLOCK" PMOD //________________________________________ //CLOCK //ZYBO Use Pin JE4 #define INIT_MYCLOCK system("echo 57 > /sys/class/gpio/export"); system("echo out > /sys/class/gpio/gpio57/direction"); #define MYCLOCK_ON system("echo 1 > /sys/class/gpio/gpio57/value"); #define MYCLOCK_OFF system("echo 0 > /sys/class/gpio/gpio57/value"); int main(void){ int myarray[ARRAYSIZE] = {//hard coded array for signal data 1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,1,0,0,1,0,0,1,0,1,0,0,1,1,0,0,1,1,0,1,0,0,0,0,0,1,0,0,1,1,1,0,0,1,1,1,0,1,1,1,1,0,0,1,0,0,0,1,0,1,0,0,1,1,1,0,0,1,0,1,0,1,0,0,1,0,1,1,0,1,0,1,1,0,0,1,1,1,1,0,0,1,0,1,0,0,1,1,1,1,1,1,0,0,1,0,0,1,1,0,1,0,0,0,0,1,0,0,0,1,1,0,0,1,0,1,1,1,0,0,0,1,0,0,0,1,0,1,0,0,0,1,0,0,1,0,1,1,1,1,0,1,1,0,1,0,0,1,0,0,0,1,0,1,0,0,1,0,0,0,1,0,0,0,1,0,1,0,1,0,1,0,1,1,0,0,0,0,0,0,0,0,1,0,1,1,0,1,1,1,1,1,0,0,1,1,1,0,0,1,1,0,1,1,0,1,1,1,0,0,1,1,1,1,1,0,0,1,0,1,0,1,0,1,1,0,1,0,0,0,1,1,1,0,1,0,1,0,1,0,1,0,1,0,1,0,0,1,0,0,0,0,1,1,1,0,1,1,1,1,0,1,1,0,1,0,1,0,1,0,0,1,0,1,1,1,0,1,1,1,0,0,1,1,1,0,1,0,0,1,0,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,0,0,1,0,1,1,0,1,0,1,1,1,0,0,0,0,0,1,0,0,0,1,0,1,1,1,1,1,1,1,0,0,0,0,0,1,1,0,1,1,1,1,1,1,1,1,0,1,1,0,1,0,0,0,1,1,1,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,1,0,1,0,1,1,1,0,0,0,1,0,1,0,1,0,0,1,1,0,0,1,1,0,1,0,0,1,0,0,1,0,1,1,1,1,1,1,0,1,1,0,1,0,1,1,1,1,1,1,0,0,1,1,0,1,1,0,0,1,1,0,1,1,0,1,0,1,0,1,0,1,0,0,1,1,1,0,1,1,0,0,0,0,1,1,0,1,1,0,1,1,1,1,1,1,1,0,1,0,1,1,0,0,0,0,0,0,0,0,0,0,0 }; INIT_SIGNAL INIT_MYCLOCK; //infinite loop int i; do{ i = 0; do{ /* 1020 is chosen because it is twice the size needed allowing for the changes in the clock. (511= 0-510, 510*2= 1020 ==> 0-1020 needed, so 1021 it is) */ if((i%2)==0) { MYCLOCK_ON; if(myarray[i/2] == 1){ SIGNAL_ON; }else{ SIGNAL_OFF; } } else if((i%2)==1) { MYCLOCK_OFF; //dont need to change the signal since it will just stay at whatever it was. } ++i; } while(i < 1021); } while(1); return 0; } I'm using the 'system' call to tell the system to output 1 volt or 0 volts onto a pin on the board (to represent the data signal and clock signal. One pin for the data and another for the clock). That was the only way I knew to tell the system to output a voltage. What can I do to make my executable program output to be at least in the magnitude of MegaHertz?

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  • Slow writing HDD speed, Ubuntu 12.04 64-bit, Thinkpad T520i

    - by pyc
    It seems that (but I'm not completely sure), that when I'm copying files from gigabit network to HDD, I can't use full potential of the network which in my case is about 60 MB/s, because HDD writing is so slow like lower than 10 MB/s, and also it's slowing down the whole system which becomes pretty much unresponsive, almost impossible to work with. Copying files to samba share residing at Ubuntu machine, connected to share from Windows 7, I'm completely sure my network equipment is OK, and there's no CPU intensive process on Ubuntu except smbd getting about 10-20% from time to time which I think is OK. Something here is burried deep I think, maybe even in kernel. Already tried to switch from AHCI to compatibility mode, and turning acpi on and off - nothing helped. So it's like HDD buffer is full and emptying slowly while machine is sluggish, load is about 3 to 4. Somebody experienced the similar problems? Some help on troubleshooting process and identifying the cause would be helpful too :) Thanks!

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  • Ubuntu 14.04 LTS 64-bit install alongside Windows 7

    - by user289222
    I've tried installing Ubuntu 14.04 LTS alongside my Windows 7 OS, following the exact procedure given by the Ubuntu website and random other tutorials. I've tried with a LiveCD and with a USB stick but I always run into the same problem. When I'm at the screen where I'm allowed to select how I want to install Ubuntu ("alongside", "erase Windows 7", "something else"), the first option says "Install Ubuntu inside Windows 7" instead of "Install Ubuntu alongside Windows 7". From pretty much all tutorials I've seen, the tutorial says that the option should say "alongside". I click "inside" anyway, and Ubuntu doesn't install at all. Instead, my computer just reboots, and goes back to the Try Ubuntu or Install Now screen. This happens regardless of using a LiveCD or a USB stick. I've also tried manually resizing my partitions using "something else". Oddly, I see 4 sda partitions: /dev/sda type size used /dev/sda1 1mb unknown Windows 7 (loader) /dev/sda2 ntsf 208mb unknown Recovery Windows Environment (loader) /dev/sda3 ntsf ~752000mb unknown Recovery Windows Environment (loader) /dev/sda4 ~18000mb unknown I try resizing the largest partition, but some sort of internal error occurs and it doesn't let me resize my partitions. Any ideas on what's going on and how to solve it?

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  • Upgrading Ubuntu(32 bit) 10.10 -> 11.04 fails and causes a kernel panic on boot

    - by Ubuntu Upgrade
    On Ubuntu 10.10 machine Upgrade to Ubuntu 11.04 using the update manager. The upgrade fails and leaves the system in an unstable state. When I reboot the system I get a kernel panic on boot. The error points to /opt/abc/runtime/lib/libc.so.6. By researching on this I found that there is a third party software abc causes problem. It has it's own runtime(libc) library. In /lib/ directory there is a link file /lib/ld-abc.so.2 ---/opt/abc/runtime/lib/ld-linux.so.2. If we rename this file to /lib/abc.so.2 or remove this file the the upgrade is success. Here is the upgrade log of where it crashes(apt-term.log) ===== Services restarted successfully. Processing triggers for libc-bin ... ldconfig deferred processing now taking place /usr/bin/dpkg: /opt/abc/runtime/lib/libc.so.6: version `GLIBC_2.11' not found (required by /usr/bin/dpkg) /usr/bin/dpkg: /opt/abc/runtime/lib/libc.so.6: version `GLIBC_2.8' not found (required by /lib/libselinux.so.1) ===== Could you please let me know what would be the problem of having a run time link library file in /lib directory. Does the ubuntu upgrade check the 3rd part runtime as well?

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  • Running external commands improved a bit

    - by Tomas Mysik
    Hi all, today we would like to show you one small improvement related to running external commands (e.g. generating documentation, running framework commands etc.) which will be available in NetBeans 7.3. First, have a look at the screenshot: As you can see, the first line represents the command that is being executed. In case of any error, this command can be easily copy & pasted to the console for deeper investigation (and proper bug reports ;). Also please notice that the Output window now supports background colors. That's all for today, as always, please test it and report all the issues or enhancements you find in NetBeans Bugzilla (component php, subcomponent Code).

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  • Can't install Ubuntu 12.04 64-bit on a dual-drive MacBook Pro 8,2

    - by kizdp
    Good afternoon, this is the first time I participate here as I'm new to Linux. I've been trying to solve the following problem for over a week without any sign of success so I hope there's a much more knowledgeable person here that can give me a solution. I have an early 2011 MacBook Pro (8,2) with Mac OS X running in a SSD. Then, instead of the Optical bay, I have a HDD in where I would like to install Ubuntu to run it natively. I've tried to do the normal installation process, with or without rEFIt, but it seems the problem resides on the communication between the device containing the Ubuntu .iso file and the laptop. It doesn't allow communication with the boot CD or USB drive. It usually says: “Loading bootlogo...” after I click on the “boot from CD, Linux Icon”. After trying several things, I would like to know if I could install Ubuntu on the HDD as an external HDD (using a friend's Window's system) and then simply put it back into my laptop so as to become an Internal HDD again. I guess, I would have to reinstall many drivers and so on, but would this approach work? Thanks in advance and sorry for this huge block of text

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  • How to manage the images for my Desktop Application

    - by NonExistent
    What's the better way to manage the image files of my app? i've been thinking about the way that i do right now (save the image as a BLOB IN db), and i ask myself if would be better to manage the image as text in my DB, i mean, convert the image to hex(length of 500), then save in the db as text, and when calling it convert it from hex to image, or something like that, but what do you consider as an Experienced Progammer that is the better way? Maybe the question is too broad, but i need to know that, and nobody answers me anywhere...

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  • Photo sharing social platform [closed]

    - by user1696497
    I am working on a photo sharing social platform like Flickr, Photobucket. To start off with I have half a million photos as of now. I want to convert all of these into a single format, compression ratio and use it as an original image. I will be storing original image, re-sized image according to layout and a thumbnail. I have started off with ruby, didn't find supporting libraries. I am considering python as it has a good image processing library and instagram is using it. I want some advise about how the image has to be processed while uploading, efficient way of storage whether database or a file system, image compressions, and precautions to be taken. I would be having profile pictures, do I need store them separately or along with the images? If I want to store the images on a file system, which file system should I use and also should I store the url or should I use any intermediate key value store like redis?

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  • Storing images in file system and returning URLs or virtually resizing and returning byte arrays?

    - by ismaelf
    I need to create a REST web service to manage user submitted images and displaying them all in a website. There are multiple websites that are going to use this service to manage and display images. The requirements are to have 5 pre-defined image sizes available. The 2 options I see are the following: The web service will create the 5 images, store them in the file system and and store the URL's in the database when the user submits the image. When the image is requested, the web service will return an array of URLs. I see this option to be a little hard on the hard drive. The estimates are 10,000 users per site, and lets say, 100 sites. The heavy processing will be done when the user submits the image and each image is going to be pulled from the File System. The web service will store just the image that the user submits in the file system and it's URL in the database. When the user request images, the web service will get the info from the DB, load the image on memory, create its 5 instances and return an object with 5 image arrays (I will probably cache the arrays). This option is harder on the processor and memory. The heavy processing will be done when the images get requested. A plus I see for option 2 is that it will give me the option to rewrite the URL of the image and make them site dependent (prettier) than having a image repository for all websites. But this is not a big deal. What do you think of these options? Do you have any other suggestions?

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  • Best practice- handling images on website

    - by Steve
    I am porting an old eCommerce site to MVC 3 and would like to take advantage of design improvements. The site currently has product images stored in 3 sizes: thumbnail, medium (for display in a list) and expanded for a zoomed look. Right now we are having to upload 3 separate images that are sized exactly right, provide 3 different names that match what the site expects, etc., it is a pain. I'd like to upload just 1 file, the large one, then let the site reduce it to needed sizes, and I'd like the flexibility to change the thumbnail and list sizes depending on user preferences, form factor (e.g. mobile, iPad, desktop), etc. so might need many copies of the same image. My question is should the image be reduced then saved several times upon upload and if so what is a good storage/naming convention? The other idea is to store just the single image but resize it programmatically before serving it to the client. Has anybody done this and what are the tradeoffs besides a few more machine cycles? How do you pass a temporary image in memory to the client (there is no URL)?

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  • 8GB, but have to run Windows Xp (32 Bit). Anything I can do with the additional memory?

    - by user12889
    I ordered a new computer with 8GB RAM with the plan to run Windows 7, 64Bit. Turns out now, that I need to run a 32Bit OS (XP or 7) due to some software which does not run on 64Bit yet (not even with any of the available compatibility settings / modes). Is there anything I can do with the memory above 4GB in this scenario? I'm willing to consider creative solutions like running a hypervisor under XP that offers the memory as a RAM-Disk for swapping etc. ? The software that does not run on 64Bit is CISCO VPN (there seems to be a half-working solution for that) and CISCO IP phone / webcam integration "CISCO Unified Video Advantage" (there is apparently no solution for that).

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  • How do I remove Skype 4.3 from Ubuntu 14.04 LTS (32-bit)

    - by Lucas W
    I installed Skype on my nephew's new Ubuntu 14.04 LTS machine, and now we've decided to remove it. But I'm not able to locate it in my Installed programs section of Ubuntu Software Center. I'm able to call it up by opening the debian package, Software Center opens it up, but where I would normally see the "Remove" button, I have a "Reinstall" button. For the life of me, I can't figure out how to uninstall Skype. Any suggestions? In case you're wondering I used the version of Skype designed for 12.xx, as there was no option available for Ubuntu 14.xx.

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  • Install Skype on Ubuntu 12.04 LTS 64-bit

    - by Samir R. Bhogayta
    For 32Bit Terminal Commands: wget http://download.skype.com/linux/skype-ubuntu-lucid_4.2.0.11-1_i386.debsudo dpkg -i skype-ubuntu-lucid_4.2.0.11-1_i386.debsudo apt-get -f install;rm skype-ubuntu-lucid_4.2.0.11-1_i386.deb For 64Bit Terminal Commands: sudo dpkg --add-architecture i386sudo apt-get install ia32-libssudo apt-get updatewget http://download.skype.com/linux/skype-ubuntu-lucid_4.2.0.11-1_i386.debsudo dpkg -i skype-ubuntu-lucid_4.2.0.11-1_i386.debsudo apt-get -f install;rm skype-ubuntu-lucid_4.2.0.11-1_i386.debAfter all of this run in terminal sudo apt-get install sni-qt:i386; This will restore the skype contact window That's all, work done in maximum 5 minutes. I use Ubuntu on 64bit and this method to install Skype worked always perfectly.

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  • video playback works only as root (ubuntu 13.10 64 bit)

    - by Hybris
    That is, video playback with anything: chrome (html 5), firefox (flash), vlc, totem, smplayer... whatever It works only if the software is started as root otherwise it freezes at the begin Interesting enough, in chrome, you can move the slider to whatever position and see the current frame updated However the video stays stil This started to happen a couple of days ago after an unidentified update Relevant output from chrome run as normal user gives some hint: NVIDIA: could not open the device file /dev/nvidia0 No output coming from firefox or vlc $ ls -l /dev/nvidia0 crw-rw-rw- 1 root root 195, 0 nov 8 21:18 /dev/nvidia0

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  • jquery ajax post callback - manipulation stops after the "third" call

    - by shanyu
    EDIT: The problem is not related to Boxy, I've run into the same issue when I've used JQuery 's load method. EDIT 2: When I take out link.remove() from inside the ajax callback and place it before ajax load, the problem is no more. Are there restrictions for manipulating elements inside an ajax callback function. I am using JQuery with Boxy plugin. When the 'Flag' link on the page is clicked, a Boxy modal pops-up and loads a form via ajax. When the user submits the form, the link (<a> tag) is removed and a new one is created from the ajax response. This mechanism works for, well, 3 times! After the 3rd, the callback function just does not remove/replace/append (tested several variations of manipulation) the element. The only hint I have is that after the 3rd call, the parent of the link becomes non-selectable. However I can't make anything of this. Sorry if this is a very trivial issue, I have no experience in client-side programming. The relevant html is below: <div class="flag-link"> <img class="flag-img" style="width: 16px; visibility: hidden;" src="/static/images/flag.png" alt=""/> <a class="unflagged" href="/i/flag/showform/9/1/?next=/users/1/ozgurisil">Flag</a> </div> Here is the relevant js code: $(document).ready(function() { $('div.flag-link a.unflagged').live('click', function(e){ doFlag(e); return false; }); ... }); function doFlag(e) { var link = $(e.target); var url = link.attr('href'); Boxy.load(url, {title:'Inappropriate Content', unloadOnHide:true, cache:false, behaviours: function(r) { $("#flag-form").live("submit", function(){ var post_url = $("#flag-form").attr('action'); boxy = Boxy.get(this); boxy.hideAndUnload(); $.post(post_url, $("#flag-form").serialize(), function(data){ par = link.parent(); par.append(data); alert (par.attr('class')); //BECOMES UNDEFINED AT THE 3RD CALL!! par.children('img.flag-img').css('visibility', 'visible'); link.remove(); }); return false; }); }}); }

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  • Configuration manipulation over all Visual Studio projects

    - by rodnower
    Hello, some one know how can I manipulate on some configuration over all projects in solution? For example, I create new configuration "Releas64" that means: "No debug, 64 bit, all files goes to c:\binaries", but I need to go over all 30 projects in our solution for to set those settings for every project. Is there some tool? Thank you for ahead.

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  • Shell extension installation not recognized by Windows 7 64-bit shell

    - by Avalanchis
    I have a Copy Hook Handler shell extension that I'm trying to install on Windows 7 64-bit. The shell extension DLL is compiled in two separate versions for 32-bit and 64-bit Windows. The DLL implements DLLRegisterServer which adds the necessary registry entries. After adding the registry entries, it calls the following line of code to nofity the Windows shell: SHChangeNotify(SHCNE_ASSOCCHANGED, SHCNF_IDLIST, NULL, NULL); Everything works great on Windows7 32-bit. The shell recognizes the extension immediately. On 64-bit, the shell extension is only recognized after the shell is restarted. Is there anything I can do to cause the extension to be recognized without restarting the 64-bit shell?

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  • Windows 7 x64 "upgrade" repair fails

    - by Polynomial
    I've been running into issues with Windows Update, which I can't seem to fix. The hotfixes don't work, nor does the Windows update readyness tool, or the manual SP1 upgrade. I get various esoteric errors which nobody seems to have a fix for. Looks like some of the update cache is corrupt and digital signatures seem to be broken on some packages / Windows Update components. Long story short, I have discovered the only option is to do a repair operation on the OS, to repair everything. It's so corrupt that only a complete replacement will fix it. According to various sources (including MSKB) one can perform a repair by running an in-place upgrade. I've got the Windows 7 Ultimate retail disc, which I've inserted into my machine. I ran setup.exe and went through in the following order: Install now Go online to get latest updates (I've also tried not getting updates) Wait for updates to be downloaded Select Windows 7 Ultimate (x64 architecture) and click next Accept the T&Cs, click next Click Upgrade At this point it spends a minute on the "checking compatibility" screen, after which I get the following error: The following issues are preventing Windows from upgrading. Cancel the upgrade, complete each task, and then restart the upgrade to continue. You can’t upgrade 64-bit Windows to a 32-bit version of Windows. To upgrade, obtain a 64-bit version of the installation disc, or go online to see how to install Windows 7 and keep your files and settings. 32-bit Windows cannot be upgraded to a 64-bit version of Windows. To upgrade, obtain a 32-bit version of the Windows installation disc. It also mentions a warning about potential conflicts with a storage driver and VS2010, but that doesn't seem to be the blocking issue. My currently installed version of Windows is Ultimate 64-bit (absolutely sure of this) and the disc is definitely a x86 / x64 combined Ultimate retail disc. There seem to be a few people who have run into this (e.g. this question), but I've not seen any answers. I've checked the event viewer, but can't spot anything in there that's related. Any idea how I can get this working? P.S: Just to pre-empt the inevitable "are you suuuuuuuuuuuuure it's x64 Ultimate?" questions:

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  • 16 bit processor , memory addressing and memory cells

    - by Zia ur Rahman
    Suppose the accumulater register of the processor is of 16 bit , now we can call this processor as 16 bit processor, that is this processor supports 16 bit addressing. now my question is how we can calculate the number of memory cells that can be addressed by 16 bit addressing? according to my calculation 2 to the power 16 becomes 65055 it means the memory have 65055 cells now if we take 1KB=1000 Bytes then this becomes 65055/1000=65.055 now this means that 65 kilo bytes memory can be used with the processor having 16 bit addressing. now if we take 1KB=1024 Bytes then this becomes 65055/1024=63.5 ,it means that 63 kilo bytes memory can be used with this processor, but people say that 64 kilo bytes memory can be used. Now tell me am i right or wrong and why i am wrong why people say that 64kb memory can be used with the processor having 16 bit addressing?

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  • C question: Padding bits in unsigned integers and bitwise operations (C89)

    - by Anonymous Question Guy
    I have a lot of code that performs bitwise operations on unsigned integers. I wrote my code with the assumption that those operations were on integers of fixed width without any padding bits. For example an array of 32 bit unsigned integers of which all 32 bits available for each integer. I'm looking to make my code more portable and I'm focused on making sure I'm C89 compliant (in this case). One of the issues that I've come across is possible padded integers. Take this extreme example, taken from the GMP manual: However on Cray vector systems it may be noted that short and int are always stored in 8 bytes (and with sizeof indicating that) but use only 32 or 46 bits. The nails feature can account for this, by passing for instance 8*sizeof(int)-INT_BIT. I've also read about this type of padding in other places. I actually read of a post on SO last night (forgive me, I don't have the link and I'm going to cite something similar from memory) where if you have, say, a double with 60 usable bits the other 4 could be used for padding and those padding bits could serve some internal purpose so they cannot be modified. So let's say for example my code is compiled on a platform where an unsigned int type is sized at 4 bytes, each byte being 8 bits, however the most significant 2 bits are padding bits. Would UINT_MAX in that case be 0x3FFFFFFF (1073741823) ? #include <stdio.h> #include <stdlib.h> /* padding bits represented by underscores */ int main( int argc, char **argv ) { unsigned int a = 0x2AAAAAAA; /* __101010101010101010101010101010 */ unsigned int b = 0x15555555; /* __010101010101010101010101010101 */ unsigned int c = a ^ b; /* ?? __111111111111111111111111111111 */ unsigned int d = c << 5; /* ?? __111111111111111111111111100000 */ unsigned int e = d >> 5; /* ?? __000001111111111111111111111111 */ printf( "a: %X\nb: %X\nc: %X\nd: %X\ne: %X\n", a, b, c, d, e ); return 0; } is it safe to XOR two integers with padding bits? wouldn't I XOR whatever the padding bits are? I can't find this behavior covered in C89. furthermore is the c var guaranteed to be 0x3FFFFFFF or if for example the two padding bits were both on in a or b would c be 0xFFFFFFFF ? same question with d and e. am i manipulating the padding bits by shifting? I would expect to see this below, assuming 32 bits with the 2 most significant bits used for padding, but I want to know if something like this is guaranteed: a: 2AAAAAAA b: 15555555 c: 3FFFFFFF d: 3FFFFFE0 e: 01FFFFFF Also are padding bits always the most significant bits or could they be the least significant bits? Thanks guys EDIT 12/19/2010 5PM EST: Christoph has answered my question. Thanks! I had also asked (above) whether padding bits are always the most significant bits. This is cited in the rationale for the C99 standard, and the answer is no. I am playing it safe and assuming the same for C89. Here is specifically what the C99 rationale says for §6.2.6.2 (Representation of Integer Types): Padding bits are user-accessible in an unsigned integer type. For example, suppose a machine uses a pair of 16-bit shorts (each with its own sign bit) to make up a 32-bit int and the sign bit of the lower short is ignored when used in this 32-bit int. Then, as a 32-bit signed int, there is a padding bit (in the middle of the 32 bits) that is ignored in determining the value of the 32-bit signed int. But, if this 32-bit item is treated as a 32-bit unsigned int, then that padding bit is visible to the user’s program. The C committee was told that there is a machine that works this way, and that is one reason that padding bits were added to C99. Footnotes 44 and 45 mention that parity bits might be padding bits. The committee does not know of any machines with user-accessible parity bits within an integer. Therefore, the committee is not aware of any machines that treat parity bits as padding bits. EDIT 12/28/2010 3PM EST: I found an interesting discussion on comp.lang.c from a few months ago. Bitwise Operator Effects on Padding Bits (VelocityReviews reader) Bitwise Operator Effects on Padding Bits (Google Groups alternate link) One point made by Dietmar which I found interesting: Let's note that padding bits are not necessary for the existence of trap representations; combinations of value bits which do not represent a value of the object type would also do.

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  • Easiest way to find the correct kademlia bucket

    - by Martin
    In the Kademlia protocol node IDs are 160 bit numbers. Nodes are stored in buckets, bucket 0 stores all the nodes which have the same ID as this node except for the very last bit, bucket 1 stores all the nodes which have the same ID as this node except for the last 2 bits, and so on for all 160 buckets. What's the fastest way to find which bucket I should put a new node into? I have my buckets simply stored in an array, and need a method like so: Bucket[] buckets; //array with 160 items public Bucket GetBucket(Int160 myId, Int160 otherId) { //some stuff goes here } The obvious approach is to work down from the most significant bit, comparing bit by bit until I find a difference, I'm hoping there is a better approach based around clever bit twiddling. Practical note: My Int160 is stored in a byte array with 20 items, solutions which work well with that kind of structure will be preferred.

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