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  • what is the most elegant way of showing first week in a month

    - by ooo
    In C#, i want to show the first week in a calendar (in a html table) and i am trying to figure out the most elegant algorithm to generate the right days. If the first day of the week is not Sunday, i want to show the days of preceding month (like you would see on a regular calendar). So, as an input you have a current month. In this case May. I want to generate this: Month: May <table> <tr> <th>S</th> <th>M</th> <th>T</th> <th>W</th> <th>TH</th> <th>F</th> <th>Sa</th> </tr> <tr> <td>25</td> <td>26</td> <td>27</td> <td>28</td> <td>29</td> <td>30</td> <td>1</td> </tr></table> so it should display something like this (ignore the alignment) S | M | T | W | Th | F | Sa | 25 - 26 - 27 - 28 - 29 - 30 - 1 given that each month would have the start of day be a different day of the week, i am trying to figure out an elegant way to get the values of this data using the DateTime object. I see it has a dayofweek property on a date. i am generating this table in C# on my server to pass down to a html page.

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  • How to get results efficiently out of an Octree/Quadtree?

    - by Reveazure
    I am working on a piece of 3D software that has sometimes has to perform intersections between massive numbers of curves (sometimes ~100,000). The most natural way to do this is to do an N^2 bounding box check, and then those curves whose bounding boxes overlap get intersected. I heard good things about octrees, so I decided to try implementing one to see if I would get improved performance. Here's my design: Each octree node is implemented as a class with a list of subnodes and an ordered list of object indices. When an object is being added, it's added to the lowest node that entirely contains the object, or some of that node's children if the object doesn't fill all of the children. Now, what I want to do is retrieve all objects that share a tree node with a given object. To do this, I traverse all tree nodes, and if they contain the given index, I add all of their other indices to an ordered list. This is efficient because the indices within each node are already ordered, so finding out if each index is already in the list is fast. However, the list ends up having to be resized, and this takes up most of the time in the algorithm. So what I need is some kind of tree-like data structure that will allow me to efficiently add ordered data, and also be efficient in memory. Any suggestions?

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  • How can I define an irregular area of the screen and find the closest point to the mouse in that area?

    - by JonathonG
    I'm looking for a method to define an area of the screen that the mouse cannot leave. I have been directed by rob mayoff, the answerer of this question, that I can use a Quartz Event Tap to detect mouse events. This puts me part of the way to the solution to THIS question. I need to define an irregular area of the screen, not just a rectangle, that the mouse cannot leave. I have been researching this and the only idea I can come up with is using a bitmap to define the irregular area, as it will be very oddly shaped. However, I am open to solutions other than using a bitmap. Since this must be done on a Mac, I've determined that I will have to use objective C / Cocoa . I need to know how to define the area and, equally importantly, how to find the closest point in the area to the mouse (so that I can move the mouse to it if the mouse tries to move outside of the area). This is similar to what the restricted area will look like: [edit:] Okay, I've come up with part of the answer to this. If I can do a basic (light-weight) point collision detection on the image mask, I can use a simple algorithm to detect the closest point to the mouse on the black area of the image. I could do this by calculating distance between a pre-defined point (P) inside the black area of the image and the target mouse position (T), taking the midpoint (M), then checking if the midpoint is inside or outside of the shape (black or white, respectively). If M is inside the shape, then move the P to M, otherwise move T to the M, continuously recalculate this until the distance between T and P is 1 pixel or less, then move the mouse to the final calculated position. All of that being said, I still need some way to test the position of the mouse against that same position on the bitmap (assume the bitmap is the same resolution as the monitor), and check if that point is black or white. All of this needs to be done in the background, without this application actually having focus, or the bitmap being visible... is this possible?

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  • How do I manipulate the format on a DataGridView that is bound to a Data Source?

    - by Jack Johnstone
    I´m using SQL Server 2005 and Visual Studio 2008, C#. In the data source (the SQL Server data table) I use the DateTime format mm/dd/yyyy, however, in a forms overview (DataGridView) users would like to see a completely other format, with year, week number and day number of week (yyww,d) which is in string format. I´ve created an algorithm for the transformation between values (date to weekday), but can I populate the affected cells with yyww,d (string) instead of mm/dd/yyyy (DateTime)? This is what I´ve been testing out, without success (and note, it´s on the last line the problem becomes obvious, as the cell value won´t accept a string on runtime - it still wants to be a DateTime...) private void DataGridViewQueryFindRequests_CellFormatting( object sender, DataGridViewCellFormattingEventArgs e) { string weekAndDay = ""; DataGridViewCell cell = DataGridViewQueryFindRequests.Rows[e.RowIndex].Cells[e.ColumnIndex]; if (cell.ColumnIndex == 13 && cell.Value == null) mEmptyRow = true; if ((cell.ColumnIndex == 14 || cell.ColumnIndex == 15) && !mEmptyRow) { weekAndDay = ClassWeeksAndDates.dateToWeekNumber(Convert.ToDateTime(cell.Value)); cell.ValueType = typeof(string); cell.Value = weekAndDay; } }

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  • Finding occurrences of element before and after the element in Array

    - by user3718040
    I am writing a algorithm, if an array contain 3 does not contain between two 1s. like this int array={5, 2, 10, 3, 15, 1, 2, 2} the above array contain 3, before 3 there is no 1 and after 3 is one 1 it should return True. int array={3,2,18,1,0,3,-11,1,3} in this array after first element of 3 there is two 1 it should return False. I have try following code public class Third { public static void main(String[] args){ int[] array = {1,2,4,3, 1}; for(int i=0;i<array.length;i++) { if(array[i]==3) { for(int j=0;j<array[i];j++) { if(array[j]==1) { System.out.println("I foud One before "+array[j]); }else { break; } System.out.println("yes i found the array:"+array[i]); } for(int z=0;z>array[i];z++) { if(array[z]==1) { System.out.println("I found after 3 is :"+array[z]); } break; } } } } } I am not getting exact result from my above code which i want.

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  • Beginner Question ; About Prime Generation in "C" - What is wrong with my code ? -

    - by alorsoncode
    I'm a third year irregular CS student and ,i just realized that i have to start coding. I passed my coding classes with lower bound grades so that i haven't a good background in coding&programming. I'm trying to write a code that generates prime numbers between given upper and lower bounds. Not knowing C well, enforce me to write a rough code then go over it to solve. I can easily set up the logic for intended function but i probably create a wrong algorithm through several different ways. Here I share my last code, i intend to calculate that when a number gives remainder Zero , it should be it self and 1 , so that count==2; What is wrong with my implementation and with my solution generating style? I hope you will warm me up to programming world, i couldn't find enough motivation and courage to get deep into programming. Thanks in Advance :) Stdio and Math.h is Included int primegen(int down,int up) { int divisor,candidate,count=0,k; for(candidate=down;candidate<=up;candidate++) { for(divisor=1;divisor<=candidate;divisor++) { k=(candidate%divisor); } if (k==0) count++; if(count==2) { printf("%d\n", candidate); count=0; } else { continue; } } } int main() { primegen(3,15); return 0; }

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  • What db fits me?

    - by afvasd
    Dear Everyone I am currently using mysql. I am finding that my schema is getting incredibly complicated. I seek to find a new db that will suit my needs: Let's assume I am building a news aggregrator (which collects news from multiple website). I then run algorithms to determine if two news from different sites are actually referring to the same topic. I run this algorithm to cluster news together. The relationship is depicted below: cluster \--news1 \--word1 \--word2 \--news2 \--word3 \--news3 \--word1 \--word3 And then I will apply some magic and determine the importance of each word. Summing all the importance of each word gives me the importance of a news article. Summing the importance of each news article gives me the importance of a cluster. Note that above cluster there are also subgroups( like split by region etc), and categories (like sports, etc) which I have to determine the importance of that in a particular day per se. I have used views in the past to do so, but I realized that views are very slow. So i will normally do an insert into an actual table and index them for better performance. As you can see this leads to multiple tables derived like (cluster, importance), (news, importance), (words, importance) etc which can get pretty messy. Also the "importance" metric will change. It has become increasingly difficult to alter tables, update data (which I am using TRUNCATE TABLE) and then inserting from null. I am currently looking into something schemaless like Mongodb. I do not need distributedness. I would very much want something that is reasonably fast (which can be indexed) and something that is a lot more flexible that traditional RDMBS. Also, I need something that has some kind of ORM because I personally like ORM a lot. I am currently using sqlalchemy Please help!

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  • Data transformation question

    - by tkm
    I have data composed of a list of employers and a list of workers. Each has a many-to-many relationship with the other (so an employer can have many workers, and a worker can have many employers). The way the data is retrieved (and given to me) is as follows: each employer has an array of workers. In other words: employer n has: worker x, worker y etc. So I have a bunch of employer objects each containing an array of workers. I need to transform this data (and basically invert the relationship). I need to have a bunch of worker objects, each containing and array of employers. In other words: worker x has: employer n1, employer n2 etc. The context is hypothetical so please don't comment on why I need this or why I am doing it this way. I would really just like help on the algorithm to perform this transformation (there isn't that much data so I would prefer readability over complex optimizations which reduce complexity). (Oh and I am using Java, but pseudocode would be fine). Thanks!

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  • How can I create an array of random numbers in C++

    - by Nick
    Instead of The ELEMENTS being 25 is there a way to randomly generate a large array of elements....10000, 100000, or even 1000000 elements and then use my insertion sort algorithms. I am trying to have a large array of elements and use insertion sort to put them in order and then also in reverse order. Next I used clock() in the time.h file to figure out the run time of each algorithm. I am trying to test with a large amount of numbers. #define ELEMENTS 25 void insertion_sort(int x[],int length); void insertion_sort_reverse(int x[],int length); int main() { clock_t tStart = clock(); int B[ELEMENTS]={4,2,5,6,1,3,17,14,67,45,32,66,88, 78,69,92,93,21,25,23,71,61,59,60,30}; int x; cout<<"Not Sorted: "<<endl; for(x=0;x<ELEMENTS;x++) cout<<B[x]<<endl; insertion_sort(B,ELEMENTS); cout <<"Sorted Normal: "<<endl; for(x=0;x<ELEMENTS;x++) cout<< B[x] <<endl; insertion_sort_reverse(B,ELEMENTS); cout <<"Sorted Reverse: "<<endl; for(x=0;x<ELEMENTS;x++) cout<< B[x] <<endl; double seconds = clock() / double(CLK_TCK); cout << "This program has been running for " << seconds << " seconds." << endl; system("pause"); return 0; }

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  • Programmatically Change Colors in C#

    - by Jason
    I am current working on a project where, as different users add text to a document, I would like the color of the text to change. Originally, I was using C#'s predefined color values and just putting the ones I wanted to use into an enum in my application and cycling through the colors as different users added annotations. This works fine, and I am okay with this solution. However, I also could have chosen to change the RGB values and derived colors that way. I'm curious about what type of algorithm would be good to change those values to get different sets of colors. This is more just an exercise of something I had thought about. To clarify a little bit, I don't want to just increment one of the color values (R, G, or B) because that wouldn't give me enough variety in my colors. But, I don't think it would also work to increment all three of equal amounts. I also have to watch out for repeating colors (up to a point). The requirements for my project anticipates, at most, 10 different reviewers.

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  • How to terminate a request in JSP (not the "return;")

    - by Genom
    I am programming a website with JSP. There are pages where user must be logged in to see it. If they are not logged in, they should see a login form. I have seen in a php code that you can make a .jsp page (single file), which checkes, whether the user is logged in or not. If not it will show the login form. If the user is logged in, nothing will be done. So in order to do that I use this structure in my JSPs: Headers, menus, etc. etc... normal stuff which would be shown such as body, footer to a logged in user. This structure is very easy to apply to all webpages. So I don't have to apply checking algorithm to each webpage! I can simply add this "" and the page is secure! So my problem is that if the user is not logged in, then only the log in form should be shown and the footer. So code should bypass the body. Therefore structured my checklogin.jsp so: If user is not logged in show the login form and footer and terminate request. The problem is that I don't know how to terminate the request... If I use "return;" then only the checklogin.jsp stops but server continues to process parent page! Therefore page has 2 footers! (1 from parent page and 1 from checklogin.jsp). How can I avoid this? (There is exit(); in php for this by the way!) Thanks for any suggestions!

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  • How duplicate an object in a list and update property of duplicated objects ?

    - by user359706
    Hello What would be the best way to duplicate an object placed in a list of items and change a property of duplicated objects ? I thought proceed in the following manner: - get object in the list by "ref" + "article" - Cloned the found object as many times as desired (n times) - Remove the object found - Add the clones in the list What do you think? A concrete example: Private List<Product> listProduct; listProduct= new List<Product>(); Product objProduit_1 = new Produit; objProduct_1.ref = "001"; objProduct_1.article = "G900"; objProduct_1.quantity = 30; listProducts.Add(objProduct_1); ProductobjProduit_2 = new Product; objProduct_2.ref = "002"; objProduct_2.article = "G900"; objProduct_2.quantity = 35; listProduits.Add(objProduct_2); desired method: public void updateProductsList(List<Product> paramListProducts,Produit objProductToUpdate, int32 nbrDuplication, int32 newQuantity){ ... } Calling method example: updateProductsList(listProducts,objProduct_1,2,15); Waiting result: Replace follow object : ref = "001"; article = "G900"; quantite = 30; By: ref = "001"; article = "G900"; quantite = 15; ref = "001"; article = "G900"; quantite = 15; The Algorithm is correct? Would you have an idea of the method implementation "updateProductsList" Thank you in advance for your help.

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  • How can I provide property-level string formatting?

    - by jhubsharp
    Not sure if the question wording is accurate, but here's what I want to do: I want to databind a class with some strings in it: class MyClass { public string MyProperty { get; set; } public string MyProperty2 { get; set; } } When databinding, everything behaves normally. On the back end, I'm writing to a file and I want MyProperty2 to always be encrypted using some encryption algorithm. I want my back-end code to write each string without needing to know that encryption is required (I want the class to know it should be encrypted, not the consumer). Can I do this with a type converter, or something similar? EDIT: There are other scenarios as well. Some booleans I want to format as "Y" or "N", other booleans I want formatted as "Enabled" / "Disabled", etc. I can write (and have written) helper methods and let the file writer call the helper methods as appropriate, I'm just wondering if there's a way to do this without the file writer needing to know which objects need which kind of formatting and let the objects tell that to the file writer.

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  • Integrating jQuery autocomplete with Google site search

    - by user1715700
    I have a bit of an odd situation. I have to implement search on a public facing website -but, that search must be able to search both web pages and have an autocomplete/suggestion functionality that comes from a list of terms that are in a DB table. So, I'm wondering a couple things: 1) should I be looking at Google search and jQuery autocomplete? 2) is there something else I should be looking at instead? 3) if this is the right path to be heading down are the enough pointers on implementation? The crux of my problem is that the terms that I need to use for the autocomplete/suggest functionality reside within a database and not on the webpages. So, I thought Google would be appropriate for search the webpages and that I could sort of fill in the blanks so to speak with these terms from the DB. I'm going to say that there are roughly 20-40,000 terms or so that need autocomplete. But that is really just a very rough guess -it could be less. I'm open to ideas and not really married to any particular solution. However, I will admit to liking the ideas of offloading the search to Google. I hear they have a good algorithm ;) Any ideas, thoughts, or leads are greatly appreciated!

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  • Why this doesnt't work in C++?

    - by user3377450
    I'm doing something and I have this: //main.cpp file template<typename t1, typename t2> std::ostream& operator<<(std::ostream& os, const std::pair<t1, t2>& pair) { return os << "< " << pair.first << " , " << pair.second << " >"; } int main() { std::map<int, int> map = { { 1, 2 }, { 2, 3 } }; std::cout << *map.begin() << std::endl;//This works std::copy(map.begin(), map.end(), std::ostream_iterator<std::pair<int,int> >(std::cout, " "));//this doesn't work } I guess this is not working because in the std::copy algorithm the operator isn't defined, but what can I do?

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  • Infrastructure for high transactional system (language & hosting suggestion help)

    - by RPS
    Some of our friends (University students) are trying to develop a twitter type application, I want to plan for at least 1000 transactions per second (I know it's wishful thinking) for initial launch. This involves several people connecting and getting updates and posting (text + images) to site. In the back end db will server the data and also calculates rankings of what to push to user based on complex algorithm on the fly real-time. Our group is familiar with Java and Tomcat/MySQL. We can also easily learn/code in PHP/MySQL. What is the best suited platform for our purpose ? Though Java seem to be easy to implement for us I am afraid that hosting will be a bit difficult. I could find cloud based php hosting services (like rackspace cloudsites) at reasonable cost. Amazon EC2 is a bit over our heads to manage on day-to-day. Also any recommendation on hosting ? (PHP or Java) We don't have millions in seed money but about $20K to start with. Any advice on above or any thing in general approach is much appreciated.

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  • Java getMethod with subclass parameter

    - by SelectricSimian
    I'm writing a library that uses reflection to find and call methods dynamically. Given just an object, a method name, and a parameter list, I need to call the given method as though the method call were explicitly written in the code. I've been using the following approach, which works in most cases: static void callMethod(Object receiver, String methodName, Object[] params) { Class<?>[] paramTypes = new Class<?>[params.length]; for (int i = 0; i < param.length; i++) { paramTypes[i] = params[i].getClass(); } receiver.getClass().getMethod(methodName, paramTypes).invoke(receiver, params); } However, when one of the parameters is a subclass of one of the supported types for the method, the reflection API throws a NoSuchMethodException. For example, if the receiver's class has testMethod(Foo) defined, the following fails: receiver.getClass().getMethod("testMethod", FooSubclass.class).invoke(receiver, new FooSubclass()); even though this works: receiver.testMethod(new FooSubclass()); How do I resolve this? If the method call is hard-coded there's no issue - the compiler just uses the overloading algorithm to pick the best applicable method to use. It doesn't work with reflection, though, which is what I need. Thanks in advance!

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  • Generic list/sublist handling

    - by user628661
    Let's say we have a class class ComplexCls { public int Fld1; public string Fld2; //could be more fields } class Cls { public int SomeField; } and then some code class ComplexClsList: List<ComplexCls>; ComplexClsList myComplexList; // fill myComplexList // same for Cls class ClsList : List<Cls>; ClsList myClsList; We want to populate myClsList from myComplexList, something like (pseudocode): foreach Complexitem in myComplexList { Cls ClsItem = new Cls(); ClsItem.SomeField = ComplexItem.Fld1; } The code to do this is easy and will be put in some method in myClsList. However I'd like to design this as generic as possible, for generic ComplexCls. Note that the exact ComplexCls is known at the moment of using this code, only the algorithm shd be generic. I know it can be done using (direct) reflection but is there other solution? Let me know if the question is not clear enough. (probably isn't). [EDIT] Basically, what I need is this: having myClsList, I need to specify a DataSource (ComplexClsList) and a field from that DataSource (Fld1) that will be used to populate my SomeField

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  • Difficulty getting Saxon into XQuery mode instead of XSLT

    - by Rosarch
    I'm having difficulty getting XQuery to work. I downloaded Saxon-HE 9.2. It seems to only want to work with XSLT. When I type: java -jar saxon9he.jar I get back usage information for XSLT. When I use the command syntax for XQuery, it doesn't recognize the parameters (like -q), and gives XSLT usage information. Here are some command line interactions: >java -jar saxon9he.jar No source file name Saxon-HE 9.2.0.6J from Saxonica Usage: see http://www.saxonica.com/documentation/using-xsl/commandline.html Options: -a Use xml-stylesheet PI, not -xsl argument -c:filename Use compiled stylesheet from file -config:filename Use configuration file -cr:classname Use collection URI resolver class -dtd:on|off Validate using DTD -expand:on|off Expand defaults defined in schema/DTD -explain[:filename] Display compiled expression tree -ext:on|off Allow|Disallow external Java functions -im:modename Initial mode -ief:class;class;... List of integrated extension functions -it:template Initial template -l:on|off Line numbering for source document -m:classname Use message receiver class -now:dateTime Set currentDateTime -o:filename Output file or directory -opt:0..10 Set optimization level (0=none, 10=max) -or:classname Use OutputURIResolver class -outval:recover|fatal Handling of validation errors on result document -p:on|off Recognize URI query parameters -r:classname Use URIResolver class -repeat:N Repeat N times for performance measurement -s:filename Initial source document -sa Use schema-aware processing -strip:all|none|ignorable Strip whitespace text nodes -t Display version and timing information -T[:classname] Use TraceListener class -TJ Trace calls to external Java functions -tree:tiny|linked Select tree model -traceout:file|#null Destination for fn:trace() output -u Names are URLs not filenames -val:strict|lax Validate using schema -versionmsg:on|off Warn when using XSLT 1.0 stylesheet -warnings:silent|recover|fatal Handling of recoverable errors -x:classname Use specified SAX parser for source file -xi:on|off Expand XInclude on all documents -xmlversion:1.0|1.1 Version of XML to be handled -xsd:file;file.. Additional schema documents to be loaded -xsdversion:1.0|1.1 Version of XML Schema to be used -xsiloc:on|off Take note of xsi:schemaLocation -xsl:filename Stylesheet file -y:classname Use specified SAX parser for stylesheet --feature:value Set configuration feature (see FeatureKeys) -? Display this message param=value Set stylesheet string parameter +param=filename Set stylesheet document parameter ?param=expression Set stylesheet parameter using XPath !option=value Set serialization option >java -jar saxon9he.jar -q:"..\w3xQueryTut.xq" Unknown option -q:..\w3xQueryTut.xq Saxon-HE 9.2.0.6J from Saxonica Usage: see http://www.saxonica.com/documentation/using-xsl/commandline.html Options: -a Use xml-stylesheet PI, not -xsl argument // etc... >java net.sf.saxon.Query -q:"..\w3xQueryTut.xq" Exception in thread "main" java.lang.NoClassDefFoundError: net/sf/saxon/Query Caused by: java.lang.ClassNotFoundException: net.sf.saxon.Query // etc... Could not find the main class: net.sf.saxon.Query. Program will exit. I'm probably making some stupid mistake. Do you know what it could be?

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  • int, short, byte performance in back-to-back for-loops

    - by runrunraygun
    (background: http://stackoverflow.com/questions/1097467/why-should-i-use-int-instead-of-a-byte-or-short-in-c) To satisfy my own curiosity about the pros and cons of using the "appropriate size" integer vs the "optimized" integer i wrote the following code which reinforced what I previously held true about int performance in .Net (and which is explained in the link above) which is that it is optimized for int performance rather than short or byte. DateTime t; long a, b, c; t = DateTime.Now; for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } a = DateTime.Now.Ticks - t.Ticks; t = DateTime.Now; for (short index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } b=DateTime.Now.Ticks - t.Ticks; t = DateTime.Now; for (byte index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } c=DateTime.Now.Ticks - t.Ticks; Console.WriteLine(a.ToString()); Console.WriteLine(b.ToString()); Console.WriteLine(c.ToString()); This gives roughly consistent results in the area of... ~950000 ~2000000 ~1700000 which is in line with what i would expect to see. However when I try repeating the loops for each data type like this... t = DateTime.Now; for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } for (int index = 0; index < 127; index++) { Console.WriteLine(index.ToString()); } a = DateTime.Now.Ticks - t.Ticks; the numbers are more like... ~4500000 ~3100000 ~300000 Which I find puzzling. Can anyone offer an explanation? NOTE: In the interest of compairing like for like i've limited the loops to 127 because of the range of the byte value type. Also this is an act of curiosity not production code micro-optimization.

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  • compile AMR-nb codec with RVCT for WinCE/Window Mobile

    - by pps
    Hello everybody, I'm working on amr speech codec (porting/optimization) I have an arm (for WinCE) optimized version from voiceage and I use it as a reference in performance testing. So far, binary produced with my lib beats the other one by around 20-30%! I use Vs2008 and I have limited access to ARM instruction set I can generate with Microsoft compiler. So I tried to look for alternative compiler to see what would be performance difference. I have RVCT compiler, but it produces elf binaries/object files. However, I run my test on a wince mobile phone (TyTn 2) so I need to find a way to run code compiled with RVCT on WinCE. Some of the options are 1) to produce assembly listing (-S option of armcc), and try to assemble with some other assembler that can create COFF (MS assembler for arm) 2) compile and convert generated ELF object file to COFF object (seems like objcopy of gnu binutils could help me with that) 3) using fromelf utility supplied by RVCT create BIN file and somehow try to mangle the bits so I can execute them ;) My first attempt is to create a simple c++ file with one exported function, compile it with RVCT and then try to run that function on the smartphone. The emitted assembly cannot be assembled by the ms assembler (not only they are not compatible, but also ms assembler rejects some of the instructions generated with RVCT compiler; ASR opcode in my case) Then I tried to convert ELF object to coff format and I can't find any information on that. There is a gcc port for ce and objcopy from that toolset is supposed to be able to do the task. However, I can't get it working. I tried different switches, but I have no idea what exactly I need to specify as bfdname for input and output format. So, I couldn't get it working either. Dumping with fromelf and using generated bin file seems to be overkill, so I decided to ask you guys if there is anything I should try to do or maybe someone has already done similar task and could help me. Basically, all I want to do is to compile my code with RVCT compiler and see what's the performance difference. My code has zero dependencies on any c runtime functions. thanks!

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  • Loading .png image from array of uint8_t into OpenGL ES texture

    - by unknownthreat
    Normally, when we want to load a texture for OpenGL ES with .png, we simply add the .png images into XCode. The .png files will be altered for optimization by XCode and these altered png files can loaded into OpenGL ES texture during the runtime. However, what I am trying to do is quite different. I am trying to load a .png file that is not from the prebuilt/compile. The png file will be transmitted externally from UDP, and it will be in the form of array of bytes. I am very sure that the png is transferred correctly, but when it comes to displaying the png image in the form of the OpenGL ES texture, the image somehow shows incorrectly. The colors that are being sent are presented but the positions are somehow very incorrect. However, the position of the colors still retain some aspects of the original position. Here: The left image shows the original .png, while the right shows the png being displayed on iPhone using OpenGL ES Texture. It looks more like the png data is not being decoded or incorrectly processed. Below is OpenGL ES code for turning the image into texture: - (void) setTextureFromImageByte: (uint8_t*)imageByte{ if (self = [super init]){ NSData* imageData = [[NSData alloc] initWithBytes: imageByte length: imageLength]; UIImage* img = [[UIImage alloc] initWithData: imageData]; CGImageRef image = img.CGImage; int width = 512; int height = 512; if (image){ int tempWidth = (int)width, tempHeight = (int)height; if ((tempWidth & (tempWidth - 1)) != 0 ){ NSLog(@"CAUTION! width is not power of 2. width == %d", tempWidth); }else if ((tempHeight & (tempHeight - 1)) != 0 ){ NSLog(@"CAUTION! height is not power of 2. height == %d", tempHeight); }else{ void *spriteData = calloc(width * 4, height * 4); CGContextRef spriteContext = CGBitmapContextCreate(spriteData, width, height, 8, width*4, CGImageGetColorSpace(image), kCGImageAlphaPremultipliedLast); CGContextDrawImage(spriteContext, CGRectMake(0.0, 0.0, width, height), image); CGContextRelease(spriteContext); glBindTexture(GL_TEXTURE_2D, 1); glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 320, 435, GL_RGBA, GL_UNSIGNED_BYTE, spriteData); free(spriteData); } }else NSLog(@"ERROR: Image not loaded..."); [img release]; [imageData release]; } } So does anyone knows how to deal with this? Is it because of iPhone only accepts altered png from XCode? What can we do in this case in order to make the png image be able to display correctly?

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  • GCC, -O2, and bitfields - is this a bug or a feature?

    - by Rooke
    Today I discovered alarming behavior when experimenting with bit fields. For the sake of discussion and simplicity, here's an example program: #include <stdio.h> struct Node { int a:16 __attribute__ ((packed)); int b:16 __attribute__ ((packed)); unsigned int c:27 __attribute__ ((packed)); unsigned int d:3 __attribute__ ((packed)); unsigned int e:2 __attribute__ ((packed)); }; int main (int argc, char *argv[]) { Node n; n.a = 12345; n.b = -23456; n.c = 0x7ffffff; n.d = 0x7; n.e = 0x3; printf("3-bit field cast to int: %d\n",(int)n.d); n.d++; printf("3-bit field cast to int: %d\n",(int)n.d); } The program is purposely causing the 3-bit bit-field to overflow. Here's the (correct) output when compiled using "g++ -O0": 3-bit field cast to int: 7 3-bit field cast to int: 0 Here's the output when compiled using "g++ -O2" (and -O3): 3-bit field cast to int: 7 3-bit field cast to int: 8 Checking the assembly of the latter example, I found this: movl $7, %esi movl $.LC1, %edi xorl %eax, %eax call printf movl $8, %esi movl $.LC1, %edi xorl %eax, %eax call printf xorl %eax, %eax addq $8, %rsp The optimizations have just inserted "8", assuming 7+1=8 when in fact the number overflows and is zero. Fortunately the code I care about doesn't overflow as far as I know, but this situation scares me - is this a known bug, a feature, or is this expected behavior? When can I expect gcc to be right about this? Edit (re: signed/unsigned) : It's being treated as unsigned because it's declared as unsigned. Declaring it as int you get the output (with O0): 3-bit field cast to int: -1 3-bit field cast to int: 0 An even funnier thing happens with -O2 in this case: 3-bit field cast to int: 7 3-bit field cast to int: 8 I admit that attribute is a fishy thing to use; in this case it's a difference in optimization settings I'm concerned about.

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  • Understanding CLR 2.0 Memory Model

    - by Eloff
    Joe Duffy, gives 6 rules that describe the CLR 2.0+ memory model (it's actual implementation, not any ECMA standard) I'm writing down my attempt at figuring this out, mostly as a way of rubber ducking, but if I make a mistake in my logic, at least someone here will be able to catch it before it causes me grief. Rule 1: Data dependence among loads and stores is never violated. Rule 2: All stores have release semantics, i.e. no load or store may move after one. Rule 3: All volatile loads are acquire, i.e. no load or store may move before one. Rule 4: No loads and stores may ever cross a full-barrier (e.g. Thread.MemoryBarrier, lock acquire, Interlocked.Exchange, Interlocked.CompareExchange, etc.). Rule 5: Loads and stores to the heap may never be introduced. Rule 6: Loads and stores may only be deleted when coalescing adjacent loads and stores from/to the same location. I'm attempting to understand these rules. x = y y = 0 // Cannot move before the previous line according to Rule 1. x = y z = 0 // equates to this sequence of loads and stores before possible re-ordering load y store x load 0 store z Looking at this, it appears that the load 0 can be moved up to before load y, but the stores may not be re-ordered at all. Therefore, if a thread sees z == 0, then it also will see x == y. If y was volatile, then load 0 could not move before load y, otherwise it may. Volatile stores don't seem to have any special properties, no stores can be re-ordered with respect to each other (which is a very strong guarantee!) Full barriers are like a line in the sand which loads and stores can not be moved over. No idea what rule 5 means. I guess rule 6 means if you do: x = y x = z Then it is possible for the CLR to delete both the load to y and the first store to x. x = y z = y // equates to this sequence of loads and stores before possible re-ordering load y store x load y store z // could be re-ordered like this load y load y store x store z // rule 6 applied means this is possible? load y store x // but don't pop y from stack (or first duplicate item on top of stack) store z What if y was volatile? I don't see anything in the rules that prohibits the above optimization from being carried out. This does not violate double-checked locking, because the lock() between the two identical conditions prevents the loads from being moved into adjacent positions, and according to rule 6, that's the only time they can be eliminated. So I think I understand all but rule 5, here. Anyone want to enlighten me (or correct me or add something to any of the above?)

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  • gcc/g++: error when compiling large file

    - by Alexander
    Hi, I have a auto-generated C++ source file, around 40 MB in size. It largely consists of push_back commands for some vectors and string constants that shall be pushed. When I try to compile this file, g++ exits and says that it couldn't reserve enough virtual memory (around 3 GB). Googling this problem, I found that using the command line switches --param ggc-min-expand=0 --param ggc-min-heapsize=4096 may solve the problem. They, however, only seem to work when optimization is turned on. 1) Is this really the solution that I am looking for? 2) Or is there a faster, better (compiling takes ages with these options acitvated) way to do this? Best wishes, Alexander Update: Thanks for all the good ideas. I tried most of them. Using an array instead of several push_back() operations reduced memory usage, but as the file that I was trying to compile was so big, it still crashed, only later. In a way, this behaviour is really interesting, as there is not much to optimize in such a setting -- what does the GCC do behind the scenes that costs so much memory? (I compiled with deactivating all optimizations as well and got the same results) The solution that I switched to now is reading in the original data from a binary object file that I created from the original file using objcopy. This is what I originally did not want to do, because creating the data structures in a higher-level language (in this case Perl) was more convenient than having to do this in C++. However, getting this running under Win32 was more complicated than expected. objcopy seems to generate files in the ELF format, and it seems that some of the problems I had disappeared when I manually set the output format to pe-i386. The symbols in the object file are by standard named after the file name, e.g. converting the file inbuilt_training_data.bin would result in these two symbols: binary_inbuilt_training_data_bin_start and binary_inbuilt_training_data_bin_end. I found some tutorials on the web which claim that these symbols should be declared as extern char _binary_inbuilt_training_data_bin_start;, but this does not seem to be right -- only extern char binary_inbuilt_training_data_bin_start; worked for me.

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