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  • How to find the jmp address during a x86 function call?

    - by Bruce
    Suppose we have a call foo statement. So when the assembler encounters a call statement it breaks it down into - push ip + 6 jmp <addr of foo> I have the return address in a register ebx. Now I want to find out the "addr of foo". How do I do it? I want to confirm that the push statement is present before the jmp. Will the memory map look something like this? ------- push (what will be the value stored in this byte?? opcode ??) ------- jmp (what will be the value stored in this byte?? opcode ??) ------- jmp byte 1 ------- jmp byte 2 ------- jmp byte 3 ------- jmp byte 4 ------- return address stored in ebx ------- What are the opcodes for push and jmp?

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  • How do you share pre-calculated data between calls to a Rails web service?

    - by Nigel Thorne
    I have a Rails app that allows users to build up a network structure and then ask questions about how to navigate around it. When adding nodes and connections these are just saved to the database. At the point you make a query of the network I calculate the shortest path from any node to any other node. Constructing this in memory takes a while (something I need to fix), but once it is there, you can instantly get the answer to any of these path questions. The question is... How do I share this network between calls to the website, so each request doesn't regenerate the paths network each time? Note: I am hosting this on apache server using passenger (mod ruby) Thoughts?

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  • how to generate large image in compact framework

    - by Buthrakaur
    I need to generate large images (A4 image at 200 DPI, PNG format would be fine) in my compact framework application. This is impossible to do in standard way due to memory limitations (such big image will throw OOMException). Is there any library which offers file-backed stream image generation? Or I could generate many smaller stripes of images (each stripe representing a row of the large image) using standard Bitmap approach, but I need to merge them together afterwards - is there any method how to merge many smaller images into one large without having to instantiate large Bitmap instance (which would again cause OOM)?

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  • .net Compiler Optimizations

    - by Dested
    I am writing an application that I need to run at incredibly low speeds. The application creates and destroys memory in creative ways throughout its run, and it works just fine. I am wondering what compiler optimizations occur so I can try to build to that. One trick off hand is that the CLR handles arrays much faster than lists, so if you need to handle a ton of elements in a List, you may be better off calling ToArray() and handling it rather than calling ElementAt() again and again. I am wondering if there is any sort of comprehensive list for this kind of thing, or maybe the SO community can create one :-)

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  • Fault exception trashes a register causing a crash in [NSInvocation invoke]

    - by Mike Weller
    I have an NSOperation which fetches some objects from a core data persistent store and sums up a few totals. Sometimes an object is deleted while the operation in in progress, so a core data fault exception occurs. I try/catch the exception while summing to ignore it because I just want to skip objects that cannot be faulted in. However, when one of these fault exceptions occurs (and I swallow it) there is a crash after the invocation returns in [NSInvocation invoke]. It's a bad memory access when dereferencing the value in r10 which according to GDB on a successful run points to one of these: (gdb) x 0x38388348 0x38388348 <OBJC_IVAR_$_NSInvocation._retdata>: 0x00000008 If a fault exception occured a value of 0x02 is in the register which causes the crash. A quick google search tells me that r10 should be saved by the callee, meaning it is not being restored by whatever code is changing it when this exception occurs. Can anybody explain this? I'm not an expert when it comes to these kinds of low-level details

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  • iphone - how to properly handle exceptional situations (signals ?)

    - by pmilosev
    Hi In my iphone app, I want to provide some sort of app termination handler that will do some final work (delete some sensitive data) before the application terminates. I want to handle as much of the termination situations as possible: 1) User terminates the app 2) The device runs out of battery 3) The system terminates the app due to some reason (e.g. out of memory or app freeze) 4) Application crashes (EXC_BAD_ACCESS or SIGSEGV) Any other exceptional situation ? What is the best way to achieve this (e.g. is applicationWillTerminate method called in situation 2) ? Is it possible to do the cleanup in a signal handler (includes iPhone Security framework calls) ? regards

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  • Firefox: how to apply XSLT from plugin to opened XML document? (how to replace document with another

    - by aloispaulin
    Hi! I've developed a plug-in for Firefox, that can read and manipulate the content of the currently opened document. I would like to apply a XLST to the document in case it is XML. I have no problem to read the XML document and apply a XSLT to it in memory, however, I have no idea of how to replace the existing document with the newly created one. Thus, I see two possible scenarios: a) I replace the document with the result of the transformation b) I apply the XSLT directly to the XML All my attempts to realize one of both possible solutions have failed... Hoping the community can provide help! Many tnx in advance! Alois

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  • Simple wrapping of C code with cython

    - by Jose
    Hi, I have a number of C functions, and I would like to call them from python. cython seems to be the way to go, but I can't really find an example of how exactly this is done. My C function looks like this: void calculate_daily ( char *db_name, int grid_id, int year, double *dtmp, double *dtmn, double *dtmx, double *dprec, double *ddtr, double *dayl, double *dpet, double *dpar ) ; All I want to do is to specify the first three parameters (a string and two integers), and recover 8 numpy arrays (or python lists. All the double arrays have N elements). My code assumes that the pointers are pointing to an already allocated chunk of memory. Also, the produced C code ought to link to some external libraries.

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  • Free object/widget in GTK?

    - by wag2639
    I've got a pack box in my GTK application and I'm replacing it every once in a while with a completely new entry (at least for now cause I'm in a hurry). Since I'm replacing it with a new instance, do I need to explicitly free from memory the old pack box contents or is there some garbage collection in GTK? If I do need to explicitly need to free the object, is there a command that will recursively go to all objects in that tree (like will it clear my button in a box container inside my main pack box)? I'm using C/GTK-2.0 (gcc v4.4.3 and GTK 2.20.0).

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  • sharepoint spweb and spsite disposal

    - by user327045
    I've been using the following code in a .NET 1.1 SharePoint 2003 environment and it works great: try { site = SPControl.GetContextSite(Context); web = site.OpenWeb(); ... } catch (Exception export) { output.Write("Caught Exception: <br/><br/>"); output.Write(export.Message + "<br><br>"); output.Write(export.StackTrace); } finally { if (web != null) web.Dispose(); if (site != null) site.Dispose(); } However, I'm currently porting the code to a .NET 2.0 SharePoint 2007 environment and I get the following error message: "Trying to use an SPWeb object that has been closed or disposed and is no longer valid." If I comment out the Dispose() code, it works fine. But won't this cause memory leaks? What's the best way to fix the problem?

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  • Reducing unnecessary same values in Class member variables ....

    - by Freshblood
    class A { public int a; public int c; } i will create 10 instances from A.Then i will create 15 instances from A again... go on. first 10 instance will have same value for a variable and next 15 instances will have again same value for a.But I don't mean that both group has same values for a .Problem is create same a value 10 times in first group and 15 times in second group on memory unnecessary. What would be Best solution or solutions for reduce unnecessary datas in this situation?

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  • How to check if a process is running or got segfaulted or terminated in linux from its pid in my mai

    - by rkbang
    Hello all, I am invoking several processes in my main and I can get the pid of that processes. Now I want to wait until all this processes have been finished and then clear the shared memory block from my parent process. Also if any of the process not finished and segfaulted I want to kill that process. So how to check from the pid of processes in my parent process code that a process is finished without any error or it gave broke down becoz of runtime error or any other cause, so that I can kill that process. Also what if I want to see the status of some other process which is not a child process but its pid is known. Code is appreciated( I am not looking for script but code ).

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  • Dynamic binary from file

    - by Aurel300
    This is a little bit of weird problem here. Say I have a C++ code, running on a specific platform. The only purpose of this code is to run files containing binary, NATIVE to that platform. Now - my question is - HOW would I get the data from these files (could even be by bits, like 1024 bits a cycle) to the memory of machine running my code so that this data would be in the execution part? In other words, can I get the data to somewhere where I can point the instruction pointer? If yes, how? I don't mind if I have to use assembler for this - just so it would work.

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  • Howto check if a object is connected to another in hibernate

    - by codevourer
    Imagine two domain object classes, A and B. A has a bidirectional one-to-many relationship to B. A is related to thousands of B. The relations must be unique, it's not possible to have a duplicate. To check if an instance of B is already connected to a given instance of A, we could perform an easy INNER JOIN but this will only ensure the already persisted relations. What about the current transient relations? class A { @OneToMany private List<B> listOfB; } If we access the listOfB and perform a check of contains() this will fetch all the connected instances of B lazy from the datasource. I only want to validate them by their primary-key. Is there an easy solution where I can do things like "Does this instance of A is connected with this instance of B?" Without loading all these data into memory and perform a based on collections?

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  • HTTP Download very Big File

    - by Luca
    I'm working at a web application in Python/Twisted. I want the user to be able to download a very big file ( 100 Mb). I don't want to load all the file in memory (of the server), of course. server side I have this idea: ... request.setHeader('Content-Type', 'text/plain') fp = open(fileName, 'rb') try: r = None while r != '': r = fp.read(1024) request.write(r) finally: fp.close() request.finish() I expected this to work, but I have problems: I'm testing with FF... It seems the browser make me wait until the file is completed downloaded, and then I have the open/save dialog box. I expected the dialog box immediately, and then the progress bar in action... Maybe I have to add something in the Http header... Something like the size of the file?

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  • From xcode not able to execute DISTINCT keyword for sqlite

    - by mac
    -(void) readProductsFromDatabase { // Setup the database object sqlite3 *database; // Init the animals Array products = [[NSMutableArray alloc] init]; // Open the database from the users filessytem if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK) { NSLog(@"db opened"); // Setup the SQL Statement and compile it for faster access const char *sqlStatement = "SELECT DISTINCT productname FROM iphone "; sqlite3_stmt *compiledStatement; if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK) { // Loop through the results and add them to the feeds array while(sqlite3_step(compiledStatement) == SQLITE_ROW) { NSLog(@"inside sqlite3 prepare"); // Read the data from the result row NSString *aName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatement, 2)]; } } // Release the compiled statement from memory sqlite3_finalize(compiledStatement); } sqlite3_close(database); } My problem is const char *sqlStatement = "SELECT DISTINCT productname FROM iphone "; This line not executing ,i am using sqlite3, thanks in advance,

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  • How to remove duplicate records in a table?

    - by Mason Wheeler
    I've got a table in a testing DB that someone apparently got a little too trigger-happy on when running INSERT scripts to set it up. The schema looks like this: ID UNIQUEIDENTIFIER TYPE_INT SMALLINT SYSTEM_VALUE SMALLINT NAME VARCHAR MAPPED_VALUE VARCHAR It's supposed to have a few dozen rows. It has about 200,000, most of which are duplicates in which TYPE_INT, SYSTEM_VALUE, NAME and MAPPED_VALUE are all identical and ID is not. Now, I could probably make a script to clean this up that creates a temporary table in memory, uses INSERT .. SELECT DISTINCT to grab all the unique values, TRUNCATE the original table and then copy everything back. But is there a simpler way to do it, like a DELETE query with something special in the WHERE clause?

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  • Output of System.out.println(object)

    - by Shaarad Dalvi
    I want to know what exactly the output tells when I do the following : class data { int a=5; } class main { public static void main(String[] args) { data dObj=new data(); System.out.println(dObj); } } I know it gives something related to object as the output in my case is data@1ae73783. I guess the '1ae73783' is a hex number. I also did some work around and printed System.out.println(dObj.hashCode()); I got number 415360643. I got an integer value. I don't know what hashCode() returns, still out of curiosity, when I converted 1ae73783 to decimal, I got 415360643! That's why I am curious that what exactly is this number?? Is this some memory location of Java's sandbox or some other thing? Any light on this matter will be helpful..thanks! :)

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  • What's your development setup? (Talking right now to my boss)

    - by Flinkman
    How do I tell my boss, that I need endless cpu power to automate my daily job? By the way, what's your setup, now in sep, 2008. How fast disks? How much memory? How many cores? How big screen? (Ok, what the hell are you doing, you may ask. I'm working in multiple environments, vmware. Have couple of build-systems running, for compatibility tests. These build systems are automated. The setup of the build system is also. Is there an another way?) Thanks!

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  • How does Photoshop (Or drawing programs) blit?

    - by user146780
    I'm getting ready to make a drawing application in Windows. I'm just wondering, do drawing programs have a memory bitmap which they lock, then set each pixel, then blit? I don't understand how Photoshop can move entire layers without lag or flicker without using hardware acceleration. Also in a program like Expression Design, I could have 200 shapes and move them around all at once with no lag. I'm really wondering how this can be done without GPU help. I don't think super efficient algorithms could justify that? Thanks

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  • Best and safest Java Profiler for production use?

    - by Pete
    I'm looking for a Java Profiler for use in a very high demand production environment, either commercial or free, that meets all of the following requirements: Lightweight integration with code (no recompile with special options, no code hooks, etc). Dropping some profiler specific .jars alongside the application code is ok. Should be able to connect/disconnect to the JVM without restarting the application. When profiling is not active, no impact to performance When profiling is active, negligible impact to performance. Very slight degradation is acceptable. Must do all the 'expected' stuff a profiler does - time spent in each method to find hotspots, object allocation/memory profiling, etc. Essentially I need something that can sit dormant in production when everything is fine without anyone knowing or caring that it is there, but then be able to connect to it hassle (and performance degradation) free to pinpoint the hard to find problems like hotspots and synchronization issues.

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  • How do I write raw binary data in Python?

    - by Chris B.
    I've got a Python program that stores and writes data to a file. The data is raw binary data, stored internally as str. I'm writing it out through a utf-8 codec. However, I get UnicodeDecodeError: 'charmap' codec can't decode byte 0x8d in position 25: character maps to <undefined> in the cp1252.py file. This looks to me like Python is trying to interpret the data using the default code page. But it doesn't have a default code page. That's why I'm using str, not unicode. I guess my questions are: How do I represent raw binary data in memory, in Python? When I'm writing raw binary data out through a codec, how do I encode/unencode it?

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  • Java Thread - Synchronization issue

    - by Yatendra Goel
    From Sun's tutorial: Synchronized methods enable a simple strategy for preventing thread interference and memory consistency errors: if an object is visible to more than one thread, all reads or writes to that object's variables are done through synchronized methods. (An important exception: final fields, which cannot be modified after the object is constructed, can be safely read through non-synchronized methods, once the object is constructed) This strategy is effective, but can present problems with liveness, as we'll see later in this lesson. Q1. Is the above statements mean that if an object of a class is going to be shared among multiple threads, then all instance methods of that class (except getters of final fields) should be made synchronized, since instance methods process instance variables?

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  • Problem in serializing

    - by Harun
    Hello Guyz, Presently I need to serialize one of my object which contains more my own classes object. But the problem is I dont want to save it in a file and then retrieve it into memory stream. Is there any way to directly serialize my object into stream. I used BinaryFormatter for seializing. First I used a MemoryStream directly to take serialize output but it is giving error at time of deserialization. But later when I serialize it with a file then close it and again reopen it , it works perfectly. But I want to take it direct into stream because in my program I need to do it frequently to pass it into network client. And using file repeatedly might slow down my software. Hope I clear my problem. Any Sugetion ?

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  • Storing object into cache using Linq classes and velocity

    - by Arun
    I careated couple of linq classes & marked the datacontext as unidirectional. Out of four classes; one is main class while other three are having the one to many relationship with first one; When I load the object of main class & put into the memory OR serialize it into an XML file; I never get the child class data while it is maked as DataContractAttribute. How can I force object to put the child class data into XML file or into cache ?

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