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• Strange EListError occurance (when accessing variable-defined index)

  - by michal

  Hi, I have a TList which stores some objects. Now I have a function which does some operations on that list: function SomeFunct(const AIndex: integer): IInterface begin if (AIndex > -1) and (AIndex < fMgr.Windows.Count ) then begin if (fMgr.Windows[AIndex] <> nil) then begin if not Supports(TForm(fMgr.Windows[AIndex]), IMyFormInterface, result) then result:= nil; end; end else result:= nil; end; now, what is really strange is that accessing fMgr.Windows with any proper index causes EListError... However if i hard-code it (in example, replace AIndex with value 0 or 1) it works fine. I tried debugging it, the function gets called twice, with arguments 0 and 1 (as supposed). while AIndex = 0, evaluating fMgr.Windows[AIndex] results in EListError at $someAddress, while evaluating fMgr.Windws[0] instead - returns proper results ... what is even more strange, even though there is an EListError, the function returns proper data ... and doesn't show anything. Just info on two EListError memory leaks on shutdown (using FastMM) any ideas what could be wrong?! Thanks in advance michal

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• How to get levels for Fry Graph readability formula?

  - by Vic

  Hi, I'm working in an application (C#) that applies some readability formulas to a text, like Gunning-Fog, Precise SMOG, Flesh-Kincaid. Now, I need to implement the Fry-based Grade formula in my program, I understand the formula's logic, pretty much you take 3 100-words samples and calculate the average on sentences per 100-words and syllables per 100-words, and then, you use a graph to plot the values. Here is a more detailed explanation on how this formula works. I already have the averages, but I have no idea on how can I tell my program to "go check the graph and plot the values and give me a level." I don't have to show the graph to the user, I only have to show him the level. I was thinking that maybe I can have all the values in memory, divided into levels, for example: Level 1: values whose sentence average are between 10.0 and 25+, and whose syllables average are between 108 and 132. Level 2: values whose sentence average are between 7.7 and 10.0, and .... so on But the problem is that so far, the only place in which I have found the values that define a level, are in the graph itself, and they aren't too much accurate, so if I apply the approach commented above, trying to take the values from the graph, my level estimations would be too much imprecise, thus, the Fry-based Grade will not be accurate. So, maybe any of you knows about some place where I can find exact values for the different levels of the Fry-based Grade, or maybe any of you can help me think in a way to workaround this. Thanks

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• Quickly determine if a number is prime in Python for numbers < 1 billion

  - by Frór

  Hi, My current algorithm to check the primality of numbers in python is way to slow for numbers between 10 million and 1 billion. I want it to be improved knowing that I will never get numbers bigger than 1 billion. The context is that I can't get an implementation that is quick enough for solving problem 60 of project Euler: I'm getting the answer to the problem in 75 seconds where I need it in 60 seconds. http://projecteuler.net/index.php?section=problems&id=60 I have very few memory at my disposal so I can't store all the prime numbers below 1 billion. I'm currently using the standard trial division tuned with 6k±1. Is there anything better than this? Do I already need to get the Rabin-Miller method for numbers that are this large. primes_under_100 = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97] def isprime(n): if n <= 100: return n in primes_under_100 if n % 2 == 0 or n % 3 == 0: return False for f in range(5, int(n ** .5), 6): if n % f == 0 or n % (f + 2) == 0: return False return True How can I improve this algorithm?

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• How to create a CGBitmapContext which works for Retina display and not wasting space for regular display?

  - by ????

  Is it true that if it is in UIKit, including drawRect, the HD aspect of Retina display is automatically handled? So does that mean in drawRect, the current graphics context for a 1024 x 768 view is actually a 2048 x 1536 pixel Bitmap context? (is there a way to print this size out to verify it). We actually enjoy the luxury of 1 point = 4 pixels automatically handled for us. However, if we use CGBitmapContextCreate, then those will really be pixels, not points? (at least if we provide a data buffer for that bitmap, the size is not for the higher resolution, but for the standard resolution, and even if we pass NULL as the buffer so that CGBitmapContextCreate handles the buffer for us, the size probably is the same as if we pass in a data buffer, and it is just standard resolution, not Retina's resolution). We can always create 2048 x 1536 for iPad 1 and iPad 2 as well as the New iPad, but it will waste memory and processor and GPU power, as it is only needed for the New iPad. So do we have to use a if () { } else { } to create such a bitmap context and how do we actually do so? And all our code CGContextMoveToPoint has to be adjusted for Retina display to use x * 2 and y * 2 vs non-retina display of just using x, y as well? That can be quite messy for the code. (or maybe we can define a local variable scaleFactor and set it to 1 for standard resolution and 2 if it is retina, so our x and y will always be x * scaleFactor, y * scaleFactor instead of just x and y.) It seems that UIGraphicsBeginImageContextWithOptions can create one for Retina automatically if the scale of 0.0 is passed in, but I don't think it can be used if I need to create the context and keep it (and using ivar or property of UIViewController to hold it). If I don't release it using UIGraphicsEndImageContext, then it stays in the graphics context stack, so it seems like I have to use CGBitmapContextCreate instead. (or do we just let it stay at the bottom of the stack and not worry about it?)

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• x86 .net application with system.OutOfMemoryException

  - by Allen

  Hi,Guys I got OutOfMemoryException after the app running for 1 day, the app totally use 1.5G memory , all consumed by managed heap, gen 2 used 200mb , and LOB used 1.3mb, however the weired thing is, 900mb of space are Free. from perf counter I saw there had number of gen 2 gc collection happened, why GC collector cannot collect those 900mb free space in gen2 and LOB? I'm really appreicate for your help. following info are from windbg: 0:000> !eeheap -gc Number of GC Heaps: 1 generation 0 starts at 0x183153f0 generation 1 starts at 0x182aa834 generation 2 starts at 0x02131000 ephemeral segment allocation context: none segment begin allocated size 02130000 02131000 0312f284 0xffe284(16769668) 07750000 07751000 0874fc5c 0xffec5c(16772188) 09e30000 09e31000 0ae2fc2c 0xffec2c(16772140) 0b230000 0b231000 0c22ffec 0xffefec(16773100) 0c230000 0c231000 0d22f6f0 0xffe6f0(16770800) 0d230000 0d231000 0e22ea10 0xffda10(16767504) 0e230000 0e231000 0f22c1c4 0xffb1c4(16757188) 10390000 10391000 1138ddf4 0xffcdf4(16764404) 154e0000 154e1000 164da90c 0xff990c(16750860) 34aa0000 34aa1000 35a9dbfc 0xffcbfc(16763900) 7aca0000 7aca1000 7bc9edfc 0xffddfc(16768508) 49760000 49761000 4a75ef64 0xffdf64(16768868) 7bca0000 7bca1000 7cc99bac 0xff8bac(16747436) 17a70000 17a71000 183313fc 0x8c03fc(9176060) Large object heap starts at 0x03131000 segment begin allocated size 03130000 03131000 041250c8 0xff40c8(16728264) 08920000 08921000 099102f8 0xfef2f8(16708344) .... .... 4c760000 4c761000 4d71d578 0xfbc578(16500088) 1bb10000 1bb11000 1ca110d0 0xf000d0(15728848) 57760000 57761000 5862d7f8 0xecc7f8(15517688) Total Size: Size: 0x5ab13450 (1521562704) bytes. ------------------------------ GC Heap Size: Size: 0x5ab13450 (1521562704) bytes. 0:000> !dumpheap -stat total 0 objects Statistics: MT Count TotalSize Class Name 73037c78 1 12 System.Configuration.GenericEnumConverter 73036da0 1 12 System.Configuration.InfiniteIntConverter .... .... 69161c3c 35025 6809420 System.Windows.EffectiveValueEntry[] 69164748 54 12471072 MS.Internal.WeakEventTable+EventKey[] 710e2228 9540 190389260 System.Byte[] 710dd2b8 1317031 339257932 System.String 0035a670 6427 902224056 Free Total 3615631 objects

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• Fast Lightweight Image Comparisson Metric Algorithm

  - by gav

  Hi All, I am developing an application for the Android platform which contains 1000+ image filters that have been 'evolved'. When a user selects a photo I want to present the most relevant filters first. This 'relevance' should be dependent on previous use cases. I have already developed tools that register when a filtered image is saved; this combination of filter and image can be seen as the training data for my system. The issue is that the comparison must occur between selecting an image and the next screen coming up. From a UI point of view I need the whole process to take less that 4 seconds; select an image- obtain a metric to use for similarity - check against use cases - return 6 closest matches. I figure with 4 seconds I can use animations and progress dialogs to keep the user happy. Due to platform contraints I am fairly limited in the computational expense of the algorithm. I have implemented a technique adapted from various online tutorials for running C code on the G1 and hence this language is available Specific Constraints; Qualcomm® MSM7201A™, 528 MHz Processor 320 x 480 Pixel bitmap in 32 bit ARGB ~ 2 seconds computational time for the native method to get the metric ~ 2 seconds to compare the metric of the current image with training data This is an academic project so all ideas are welcome, anything you can think of or have heard about would be of interest to me. My ideas; I want to keep the complexity down (O(n*m)?) by using pixel data only rather than a neighbourhood function I was looking at using the Colour historgram/Greyscale histogram/Texture/Entropy of the image, combining them to make the measure. There will be an obvious loss of information but I need the resultant metric to be substantially smaller than the memory footprint of the image (~0.512 MB) As I said, any ideas to direct my research would be fantastic. Kind regards, Gavin

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• PHPUnit reporting "Aborted" no matter what tests are run

  - by GrumpyCanuck

  Having a weird problem with PHPUnit. We're using PHPUnit as part of a continuous integration environment, that contains one app written using Zend Framework and one app written using CodeIgniter. Unit tests run just fine under Zend Framework, but whenever I run the tests for CodeIgniter using fooStack's CIUnit bridge, I always get the same problem at the end: PHPUnit 3.4.14 by Sebastian Bergmann. ............... . Time: 1 second, Memory: 7.00Mb OK (16 tests, 14 assertions) Aborted First off, I do not know what those empty spaces between the . means. Secondly, no matter what test I run (all of them or each one separately) I get the same Aborted message at the very end. The tests themselves do not contain any exit or die statements. When I run the same version of PHPUnit on my laptop (running OS-X Snow Leopard and same version of Zend Server Community Edition) I do not get that aborted message. Running PHP 5.3.2 on Ubuntu installed using Zend Server Community Edition. Any help with this would be greatly appreciated.

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• vector::erase with pointer member

  - by matt

  I am manipulating vectors of objects defined as follow: class Hyp{ public: int x; int y; double wFactor; double hFactor; char shapeNum; double* visibleShape; int xmin, xmax, ymin, ymax; Hyp(int xx, int yy, double ww, double hh, char s): x(xx), y(yy), wFactor(ww), hFactor(hh), shapeNum(s) {visibleShape=0;shapeNum=-1;}; //Copy constructor necessary for support of vector::push_back() with visibleShape Hyp(const Hyp &other) { x = other.x; y = other.y; wFactor = other.wFactor; hFactor = other.hFactor; shapeNum = other.shapeNum; xmin = other.xmin; xmax = other.xmax; ymin = other.ymin; ymax = other.ymax; int visShapeSize = (xmax-xmin+1)*(ymax-ymin+1); visibleShape = new double[visShapeSize]; for (int ind=0; ind<visShapeSize; ind++) { visibleShape[ind] = other.visibleShape[ind]; } }; ~Hyp(){delete[] visibleShape;}; }; When I create a Hyp object, allocate/write memory to visibleShape and add the object to a vector with vector::push_back, everything works as expected: the data pointed by visibleShape is copied using the copy-constructor. But when I use vector::erase to remove a Hyp from the vector, the other elements are moved correctly EXCEPT the pointer members visibleShape that are now pointing to wrong addresses! How to avoid this problem? Am I missing something?

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• How to enforce foreign keys using Xerial SQLite JDBC?

  - by Space_C0wb0y

  According to their release notes, the Xerial SQLite JDBC driver supports foreign keys since version 3.6.20.1. I have tried some time now to get a foreign key constraint to be enforced, but to no avail. Here is what I came up with: public static void main(String[] args) throws ClassNotFoundException, SQLException { Class.forName("org.sqlite.JDBC"); SQLiteConfig config = new SQLiteConfig(); config.enforceForeignKeys(true); Connection connection = DriverManager.getConnection("jdbc:sqlite::memory:", config.toProperties()); connection.createStatement().executeUpdate( "CREATE TABLE artist(" + "artistid INTEGER PRIMARY KEY, " + "artistname TEXT);"); connection.createStatement().executeUpdate( "CREATE TABLE track("+ "trackid INTEGER," + "trackname TEXT," + "trackartist INTEGER," + "FOREIGN KEY(trackartist) REFERENCES artist(artistid)" + ");"); connection.createStatement().executeUpdate( "INSERT INTO track VALUES(14, 'Mr. Bojangles', 3)"); } The table definitions are taken directly from the sample in the SQLite documentation. This is supposed to fail, but it doesn't. I also checked, and it really inserts the tuple (no ignore or something like that). Does anyone have any experience with that, or knows how to make it work?

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• Unit testing opaque structure based C API

  - by Nicolas Goy

  I have a library I wrote with API based on opaque structures. Using opaque structures has a lot of benefits and I am very happy with it. Now that my API are stable in term of specifications, I'd like to write a complete battery of unit test to ensure a solid base before releasing it. My concern is simple, how do you unit test API based on opaque structures where the main goal is to hide the internal logic? For example, let's take a very simple object, an array with a very simple test: WSArray a = WSArrayCreate(); int foo = 5; WSArrayAppendValue(a, &foo); int *bar = WSArrayGetValueAtIndex(a, 0); if(&foo != bar) printf("Eroneous value returned\n"); else printf("Good value returned\n"); WSRelease(a); Of course, this tests some facts, like the array actually acts as wanted with 1 value, but when I write unit tests, at least in C, I usualy compare the memory footprint of my datastructures with a known state. In my example, I don't know if some internal state of the array is broken. How would you handle that? I'd really like to avoid adding codes in the implementation files only for unit testings, I really emphasis loose coupling of modules, and injecting unit tests into the implementation would seem rather invasive to me. My first thought was to include the implementation file into my unit test, linking my unit test statically to my library. For example: #include <WS/WS.h> #include <WS/Collection/Array.c> static void TestArray(void) { WSArray a = WSArrayCreate(); /* Structure members are available because we included Array.c */ printf("%d\n", a->count); } Is that a good idea? Of course, the unit tests won't benefit from encapsulation, but they are here to ensure it's actually working.

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• ASP.NET MVC Paging for a search form

  - by James Alexander

  I've read several different posts on paging w/ in MVC but none describe a scenario where I have something like a search form and then want to display the results of the search criteria (with paging) beneath the form once the user clicks submit. My problem is that, the paging solution I'm using will create <a href="..."> links that will pass the desired page like so: http://mysite.com/search/2/ and while that's all fine and dandy, I don't have the results of the query being sent to the db in memory or anything so I need to query the DB again. If the results are handled by the POST controller action for /Search and the first page of the data is rendered as such, how do I get the same results (based on the form criteria specified by the user) when the user clicks to move to page 2? Some javascript voodoo? Leverage Session State? Make my GET controller action have the same variables expected by the search criteria (but optional), when the GET action is called, instantiate a FormCollection instance, populate it and pass it to the POST action method (there-by satisfying DRY)? Can someone point me in the right direction for this scenario or provide examples that have been implemented in the past? Thanks!

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• Anonymous union definition/declaration in a macro GNU vs VS2008

  - by Alan_m

  I am attempting to alter an IAR specific header file for a lpc2138 so it can compile with Visual Studio 2008 (to enable compatible unit testing). My problem involves converting register definitions to be hardware independent (not at a memory address) The "IAR-safe macro" is: #define __IO_REG32_BIT(NAME, ADDRESS, ATTRIBUTE, BIT_STRUCT) \ volatile __no_init ATTRIBUTE union \ { \ unsigned long NAME; \ BIT_STRUCT NAME ## _bit; \ } @ ADDRESS //declaration //(where __gpio0_bits is a structure that names //each of the 32 bits as P0_0, P0_1, etc) __IO_REG32_BIT(IO0PIN,0xE0028000,__READ_WRITE,__gpio0_bits); //usage IO0PIN = 0x0xAA55AA55; IO0PIN_bit.P0_5 = 0; This is my comparable "hardware independent" code: #define __IO_REG32_BIT(NAME, BIT_STRUCT)\ volatile union \ { \ unsigned long NAME; \ BIT_STRUCT NAME##_bit; \ } NAME; //declaration __IO_REG32_BIT(IO0PIN,__gpio0_bits); //usage IO0PIN.IO0PIN = 0xAA55AA55; IO0PIN.IO0PIN_bit.P0_5 = 1; This compiles and works but quite obviously my "hardware independent" usage does not match the "IAR-safe" usage. How do I alter my macro so I can use IO0PIN the same way I do in IAR? I feel this is a simple anonymous union matter but multiple attempts and variants have proven unsuccessful. Maybe the IAR GNU compiler supports anonymous unions and vs2008 does not. Thank you.

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• AS3 using PrintJob to print a MovieClip

  - by Chris Waugh

  Hello, I am currently trying to create a function which will allow me to pass in a movieclip and print it. Here is the simplified version of the function: function printMovieClip(clip:MovieClip) { var printJob:PrintJob = new PrintJob(); var numPages:int = 0; var printY:int = 0; var printHeight:Number; if ( printJob.start() ) { /* Resize movie clip to fit within page width */ if (clip.width > printJob.pageWidth) { clip.width = printJob.pageWidth; clip.scaleY = clip.scaleX; } numPages = Math.ceil(clip.height / printJob.pageHeight); /* Add pages to print job */ for (var i:int = 0; i < numPages; i++) { printJob.addPage(clip, new Rectangle(0, printY, printJob.pageWidth, printJob.pageHeight)); printY += printJob.pageHeight; } /* Send print job to printer */ printJob.send(); /* Delete job from memory */ printJob = null; } } printMovieClip( testMC ); Unfortunately this is not working as expected i.e. printing the full width of the Movieclip and doing page breaks on the length. Any help with this would be greatly appreciated. Many thanks, Chris

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• CUDA Kernel Not Updating Global Variable

  - by Taher Khokhawala

  I am facing the following problem in a CUDA kernel. There is an array "cu_fx" in global memory. Each thread has a unique identifier jj and a local loop variable ii and a local float variable temp. Following code is not working. It is not at all changing cu_fx[jj]. At the end of loop cu_fx[jj] remains 0. ii = 0; cu_fx[jj] = 0; while(ii < l) { if(cu_y[ii] > 0) cu_fx[jj] += (cu_mu[ii]*cu_Kernel[(jj-start_row)*Kernel_w + ii]); else cu_fx[jj] -= (cu_mu[ii]*cu_Kernel[(jj-start_row)*Kernel_w + ii]); ii++; } But when I rewrite it using a temporary variable temp, it works fine. ii = 0; temp = 0; while(ii < l) { if(cu_y[ii] > 0) temp += (cu_mu[ii]*cu_Kernel[(jj-start_row)*Kernel_w + ii]); else temp -= (cu_mu[ii]*cu_Kernel[(jj-start_row)*Kernel_w + ii]); ii++; } cu_fx[jj] = temp; Can somebody please help with this problem. Thanking in advance.

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• Do fluent interfaces significantly impact runtime performance of a .NET application?

  - by stakx

  I'm currently occupying myself with implementing a fluent interface for an existing technology, which would allow code similar to the following snippet: using (var directory = Open.Directory(@"path\to\some\directory")) { using (var file = Open.File("foobar.html").In(directory)) { // ... } } In order to implement such constructs, classes are needed that accumulate arguments and pass them on to other objects. For example, to implement the Open.File(...).In(...) construct, you would need two classes: // handles 'Open.XXX': public static class OpenPhrase { // handles 'Open.File(XXX)': public static OpenFilePhrase File(string filename) { return new OpenFilePhrase(filename); } // handles 'Open.Directory(XXX)': public static DirectoryObject Directory(string path) { // ... } } // handles 'Open.File(XXX).XXX': public class OpenFilePhrase { internal OpenFilePhrase(string filename) { _filename = filename } // handles 'Open.File(XXX).In(XXX): public FileObject In(DirectoryObject directory) { // ... } private readonly string _filename; } That is, the more constituent parts statements such as the initial examples have, the more objects need to be created for passing on arguments to subsequent objects in the chain until the actual statement can finally execute. Question: I am interested in some opinions: Does a fluent interface which is implemented using the above technique significantly impact the runtime performance of an application that uses it? With runtime performance, I refer to both speed and memory usage aspects. Bear in mind that a potentially large number of temporary, argument-saving objects would have to be created for only very brief timespans, which I assume may put a certain pressure on the garbage collector. If you think there is significant performance impact, do you know of a better way to implement fluent interfaces?

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• Python subprocess Popen.communicate() equivalent to Popen.stdout.read()?

  - by Christophe

  Very specific question (I hope): What are the differences between the following three codes? (I expect it to be only that the first does not wait for the child process to be finished, while the second and third ones do. But I need to be sure this is the only difference...) I also welcome other remarks/suggestions (though I'm already well aware of the shell=True dangers and cross-platform limitations) Note that I already read Python subprocess interaction, why does my process work with Popen.communicate, but not Popen.stdout.read()? and that I do not want/need to interact with the program after. Also note that I already read Alternatives to Python Popen.communicate() memory limitations? but that I didn't really get it... First code: from subprocess import Popen, PIPE def exe_f(command='ls -l', shell=True): "Function to execute a command and return stuff" process = Popen(command, shell=shell, stdout=PIPE, stderr=PIPE) stdout = process.stdout.read() stderr = process.stderr.read() return process, stderr, stdout Second code: from subprocess import Popen, PIPE from subprocess import communicate def exe_f(command='ls -l', shell=True): "Function to execute a command and return stuff" process = Popen(command, shell=shell, stdout=PIPE, stderr=PIPE) (stdout, stderr) = process.communicate() return process, stderr, stdout Third code: from subprocess import Popen, PIPE from subprocess import wait def exe_f(command='ls -l', shell=True): "Function to execute a command and return stuff" process = Popen(command, shell=shell, stdout=PIPE, stderr=PIPE) code = process.wait() stdout = process.stdout.read() stderr = process.stderr.read() return process, stderr, stdout Thanks.

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• Space-saving character encoding for japanese?

  - by Constantin

  In my opinion a common problem: character encoding in combination with a bitmap-font. Most multi-language encodings have an huge space between different character types and even a lot of unused code points there. So if I want to use them I waste a lot of memory (not only for saving multi-byte text - i mean specially for spaces in my bitmap-font) - and VRAM is mostly really valuable... So the only reasonable thing seems to be: Using an custom mapping on my texture for i.e. UTF-8 characters (so that no space is waste). BUT: This effort seems to be same with use an own proprietary character encoding (so also own order of characters in my texture). In my specially case I got texture space for 4096 different characters and need characters to display latin languages as well as japanese (its a mess with utf-8 that only support generall cjk codepages). Had somebody ever a similiar problem (I really wonder, if not)? If theres already any approach? Edit: The same Problem is described here http://www.tonypottier.info/Unicode_And_Japanese_Kanji/ but it doesnt provide an real solution how to save these bitmapfont mappings to utf-8 space efficent. So any further help is welcome!

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• Why doesn't gcc remove this check of a non-volatile variable?

  - by Thomas

  This question is mostly academic. I ask out of curiosity, not because this poses an actual problem for me. Consider the following incorrect C program. #include <signal.h> #include <stdio.h> static int running = 1; void handler(int u) { running = 0; } int main() { signal(SIGTERM, handler); while (running) ; printf("Bye!\n"); return 0; } This program is incorrect because the handler interrupts the program flow, so running can be modified at any time and should therefore be declared volatile. But let's say the programmer forgot that. gcc 4.3.3, with the -O3 flag, compiles the loop body (after one initial check of the running flag) down to the infinite loop .L7: jmp .L7 which was to be expected. Now we put something trivial inside the while loop, like: while (running) putchar('.'); And suddenly, gcc does not optimize the loop condition anymore! The loop body's assembly now looks like this (again at -O3): .L7: movq stdout(%rip), %rsi movl $46, %edi call _IO_putc movl running(%rip), %eax testl %eax, %eax jne .L7 We see that running is re-loaded from memory each time through the loop; it is not even cached in a register. Apparently gcc now thinks that the value of running could have changed. So why does gcc suddenly decide that it needs to re-check the value of running in this case?

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• When should I be cautious using data binding in .NET?

  - by Ben McCormack

  I just started working on a small team of .NET programmers about a month ago and recently got in a discussion with our team lead regarding why we don't use databinding at all in our code. Every time we work with a data grid, we iterate through a data table and populate the grid row by row; the code usually looks something like this: Dim dt as DataTable = FuncLib.GetData("spGetTheData ...") Dim i As Integer For i = 0 To dt.Rows.Length - 1 '(not sure why we do not use a for each here)' gridRow = grid.Rows.Add() gridRow(constantProductID).Value = dt("ProductID").Value gridRow(constantProductDesc).Value = dt("ProductDescription").Value Next '(I am probably missing something in the code, but that is basically it)' Our team lead was saying that he got burned using data binding when working with Sheridan Grid controls, VB6, and ADO recordsets back in the nineties. He's not sure what the exact problem was, but he remembers that binding didn't work as expected and caused him some major problems. Since then, they haven't trusted data binding and load the data for all their controls by hand. The reason the conversation even came up was because I found data binding to be very simple and really liked separating the data presentation (in this case, the data grid) from the in-memory data source (in this case, the data table). "Loading" the data row by row into the grid seemed to break this distinction. I also observed that with the advent of XAML in WPF and Silverlight, data-binding seems like a must-have in order to be able to cleanly wire up a designer's XAML code with your data. When should I be cautious of using data-binding in .NET?

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• error detection/correction/recovery in serial protocols

  - by Jason S

  I have some designing to do for a serial protocol and am running into some questions that I figure must have been considered elsewhere. So I'm wondering if there are some recommendations for best practices in designing serial protocols. (Please either state a fact that is easily verifiable, or cite a reputable source if you make a claim.) General recommendations for websites/books are also welcome. In particular I have to deal with issues like parsing a stream of bytes into packets verifying a packet is correct (easy with a CRC, for instance) identifying reasonable types of errors that can occur (e.g. in a point-to-point serial stream, sporadic single bit errors, and dropped series of bytes, are both likely, but extra phantom bytes are unlikely; whereas with a record stored in flash memory or on a disk drive the types of errors that predominate are different) error correction or recovery (if I detect an error in a packet, can I correct it? If not, can I resync to the boundary of the next packet?) how to make variable-length packets robust to error correction / recovery. Any suggestions?

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• working with large sprite sheets on iphone

  - by lukya

  Hi All, I am trying to use sprite sheet animation in my application. The first POC with a small sprite sheet worked fine but as i change the sprite sheet to a bigger one, i get "check_safe_call: could not restore current frame" warning and the application quits. A quick search revealed that this problem meant my app is taking too much memory or the image is too huge in dimension. My image is 4.9 Mb and dimensions are 6720 * 10080 (oops!!). i read that iphone allows maximum 3 Mb image with dimensions up to 1024 * 1024. Also that the sprite sheet image dimensions should be a power of two. So please let me know how i can use a sprite sheet this big. One approach could be to cut the sprite sheet into many smaller sprite sheets and use them one at a time. Please suggest if you know any other/better approach to accommodate bigger sprite sheets and whether the problem with my sprite sheet is size (4.9 Mb) OR dimensions (6720 * 10080). (Just FYI, i am not trying to play a movie so using MP4 file instead is not an option for me. i need to animate the sprite sheet based on accelerometer input and i have been able to achieve that in my POC with smaller sprite sheet.) Thanks, Swapnil

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• bug in NHunspell spelling checker

  - by Nikhil K

  I am using NHunspell for checking spelling.I added NHunspell.dll as a reference to my asp.net page.I added the namespace System.NHunspell. The problem i am facing is related to IDisposible. I put the downloaded code of NHunspell inside the button event. protected void Button1_Click(object sender, EventArgs e) { using (Hunspell hunspell = new Hunspell("en_us.aff", "en_us.dic")) { bool correct = hunspell.Spell("Recommendation"); var suggestions = hunspell.Suggest("Recommendatio"); foreach (string suggestion in suggestions) { Console.WriteLine("Suggestion is: " + suggestion); } } // Hyphen using (Hyphen hyphen = new Hyphen("hyph_en_us.dic")) { var hyphenated = hyphen.Hyphenate("Recommendation"); } * using (MyThes thes = new MyThes("th_en_us_new.idx", "th_en_us_new.dat")) { using (Hunspell hunspell = new Hunspell("en_us.aff", "en_us.dic")) { ThesResult tr = thes.Lookup("cars", hunspell); foreach (ThesMeaning meaning in tr.Meanings) { Console.WriteLine(" Meaning: " + meaning.Description); foreach (string synonym in meaning.Synonyms) { Console.WriteLine(" Synonym: " + synonym); } } } } The * shown above is the line of error.The error is: " type used in a using statement must be implicitly convertible to 'System.IDisposable'". Also there is a warning on that line :"'NHunspell.MyThes.MyThes(string, string)' is obsolete: 'idx File is not longer needed, MyThes works completely in memory'"; Can any one help me to correct this???

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• Is there a fast alternative to creating a Texture2D from a Bitmap object in XNA?

  - by Matthew Bowen

  I've looked around a lot and the only methods I've found for creating a Texture2D from a Bitmap are: using (MemoryStream s = new MemoryStream()) { bmp.Save(s, System.Drawing.Imaging.ImageFormat.Png); s.Seek(0, SeekOrigin.Begin); Texture2D tx = Texture2D.FromFile(device, s); } and Texture2D tx = new Texture2D(device, bmp.Width, bmp.Height, 0, TextureUsage.None, SurfaceFormat.Color); tx.SetData<byte>(rgbValues, 0, rgbValues.Length, SetDataOptions.NoOverwrite); Where rgbValues is a byte array containing the bitmap's pixel data in 32-bit ARGB format. My question is, are there any faster approaches that I can try? I am writing a map editor which has to read in custom-format images (map tiles) and convert them into Texture2D textures to display. The previous version of the editor, which was a C++ implementation, converted the images first into bitmaps and then into textures to be drawn using DirectX. I have attempted the same approach here, however both of the above approaches are significantly too slow. To load into memory all of the textures required for a map takes for the first approach ~250 seconds and for the second approach ~110 seconds on a reasonable spec computer. If there is a method to edit the data of a texture directly (such as with the Bitmap class's LockBits method) then I would be able to convert the custom-format images straight into a Texture2D and hopefully save processing time. Any help would be very much appreciated. Thanks

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• Javascript force GC collection? / Forcefully free object?

  - by plash

  I have a js function for playing any given sound using the Audio interface (creating a new instance for every call). This works quite well, until about the 32nd call (sometimes less). This issue is directly related to the release of the Audio instance. I know this because I've allowed time for the GC in Chromium to run and it will allow me to play another 32 or so sounds again. Here's an example of what I'm doing: <html><head> <script language="javascript"> function playSound(url) { snd = new Audio(url); snd.play(); delete snd; snd = null; } </script> </head> <body> <a href="#" onclick="playSound('blah.mp3');">Play sound</a> </body></html> I also have this, which works well for pages that have less than 32 playSound calls: var AudioPlayer = { cache: {}, play: function(url) { if (!AudioPlayer.cache[url]) AudioPlayer.cache[url] = new Audio(url); AudioPlayer.cache[url].play(); } }; But this will not work for what I want to do (dynamically replace a div with other content (from separate files), which have even more sounds on them - 1. memory usage would easily skyrocket, 2. many sounds will never play). I need a way to release the sound immediately. Is it possible to do this? I have found no free/close/unload method for the Audio interface. The pages will be viewed locally, so the constant loading of sounds is not a big factor at all (and most sounds are rather short).

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• Segmentation fault on writing char to char* address

  - by Lukas Dojcak

  hi guys, i've got problem with my little C program. Maybe you could help me. char* shiftujVzorku(char* text, char* pattern, int offset){ char* pom = text; int size = 0; int index = 0; while(*(text + size) != '\0'){ size++; } while(*(pom + index) != '\0'){ if(overVzorku(pom + index, pattern)){ while(*pattern != '\0'){ //vyment *pom s *pom + offset if(pom + index + offset < text + size){ char x = *(pom + index + offset); char y = *(pom + index); int adresa = *(pom + index + offset); *(pom + index + offset) = y; <<<<<< SEGMENTATION FAULT *(pom + index) = x; //*pom = *pom - *(pom + offset); //*(pom + offset) = *(pom + offset) + *pom; //*pom = *(pom + offset) - *pom; } else{ *pom = *pom - *(pom + offset - size); *(pom + offset - size) = *(pom + offset - size) + *pom; *pom = *(pom + offset - size) - *pom; } pattern++; } break; } index++; } return text; } Isn't important what's the programm doing. Mayby there's lot of bugs. But, why do I get SEGMENTATION FAULT (for destination see code) at this line? I'm, trying to write some char value to memory space, with help of address "pom + offset + index". Thanks for everything helpful. :)

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