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  • Display a ranking grid for game : optimization of left outer join and find a player

    - by Jerome C.
    Hello, I want to do a ranking grid. I have a table with different values indexed by a key: Table SimpleValue : key varchar, value int, playerId int I have a player which have several SimpleValue. Table Player: id int, nickname varchar Now imagine these records: SimpleValue: Key value playerId for 1 1 int 2 1 agi 2 1 lvl 5 1 for 6 2 int 3 2 agi 1 2 lvl 4 2 Player: id nickname 1 Bob 2 John I want to display a rank of these players on various SimpleValue. Something like: nickname for lvl Bob 1 5 John 6 4 For the moment I generate an sql query based on which SimpleValue key you want to display and on which SimpleValue key you want to order players. eg: I want to display 'lvl' and 'for' of each player and order them on the 'lvl' The generated query is: SELECT p.nickname as nickname, v1.value as lvl, v2.value as for FROM Player p LEFT OUTER JOIN SimpleValue v1 ON p.id=v1.playerId and v1.key = 'lvl' LEFT OUTER JOIN SimpleValue v2 ON p.id=v2.playerId and v2.key = 'for' ORDER BY v1.value This query runs perfectly. BUT if I want to display 10 different values, it generates 10 'left outer join'. Is there a way to simplify this query ? I've got a second question: Is there a way to display a portion of this ranking. Imagine I've 1000 players and I want to display TOP 10, I use the LIMIT keyword. Now I want to display the rank of the player Bob which is 326/1000 and I want to display 5 rank player above and below (so from 321 to 331 position). How can I achieve it ? thanks.

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  • Simple neon optimization in Android

    - by Peter
    In my Android application, I use a bunch of open source libraries such as libyuv, libvpx, libcrypto, libssl, etc. Some of them come with Android.mk. For others, I hand-crafted Android.mk. The code is built only for arm for now. Here is my Application.mk: APP_ABI := armeabi-v7a APP_OPTIM := release APP_STL := gnustl_static APP_CPPFLAGS := -frtti I am looking for way to generate binaries that are optimized for neon. Browsing the net, I found the following setting that someone is using in his Android.mk: LOCAL_CFLAGS += -mfloat-abi=softfp -mfpu=neon -march=armv7 I wonder if I simply put this setting in Application.mk, will it automatically get applied across all the libraries? A step before each library is built is the following: include $(CLEAR_VARS) Is it better to include LOCAL_CFLAGS directive after this line (instead of including it in Application.mk)? Finally, why doesn't ndk-build automatically optimize for neon when it sees armabi in Application.mk? Regards.

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  • MongoDB vs CouchDB (Speed optimization)

    - by Edward83
    Hi! I made some tests of speed to compare MongoDB and CouchDB. Only inserts were while testing. I got MongoDB 15x faster than CouchDB. I know that it is because of sockets vs http. But, it is very interesting for me how can I optimize inserts in CouchDB? Test platform: Windows XP SP3 32 bit. I used last versions of MongoDB, MongoDB C# Driver and last version of installation package of CouchDB for Windows. Thanks!

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  • url optimization in rails?

    - by piemesons
    Hello I want to create seo optimize url in rails.Same like done in stackoverflow. Right now this is my url http://localhost:3000/questions/56 I want to make it something like this:- http://localhost:3000/questions/56/this-is-my-optimized-url i am using restful approach. is there any plug-in available for this.

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  • ControlCollection extension method optimization

    - by Johan Leino
    Hi, got question regarding an extension method that I have written that looks like this: public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance) where T : class { T control; foreach (Control ctrl in instance) { if ((control = ctrl as T) != null) { yield return control; } foreach (T child in FindControlsOfType<T>(ctrl.Controls)) { yield return child; } } } public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance, Func<T, bool> match) where T : class { return FindControlsOfType<T>(instance).Where(match); } The idea here is to find all controls that match a specifc criteria (hence the Func<..) in the controls collection. My question is: Does the second method (that has the Func) first call the first method to find all the controls of type T and then performs the where condition or does the "runtime" optimize the call to perform the where condition on the "whole" enumeration (if you get what I mean). secondly, are there any other optimizations that I can do to the code to perform better. An example can look like this: var checkbox = this.Controls.FindControlsOfType<MyCustomCheckBox>( ctrl => ctrl.CustomProperty == "Test" ) .FirstOrDefault();

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  • Stored procedure optimization

    - by George Zacharia
    Hi, i have a stored procedure which takes lot of time to execure .Can any one suggest a better approch so that the same result set is achived. ALTER PROCEDURE [dbo].[spFavoriteRecipesGET] @USERID INT, @PAGENUMBER INT, @PAGESIZE INT, @SORTDIRECTION VARCHAR(4), @SORTORDER VARCHAR(4),@FILTERBY INT AS BEGIN DECLARE @ROW_START INT DECLARE @ROW_END INT SET @ROW_START = (@PageNumber-1)* @PageSize+1 SET @ROW_END = @PageNumber*@PageSize DECLARE @RecipeCount INT DECLARE @RESULT_SET_TABLE TABLE ( Id INT NOT NULL IDENTITY(1,1), FavoriteRecipeId INT, RecipeId INT, DateAdded DATETIME, Title NVARCHAR(255), UrlFriendlyTitle NVARCHAR(250), [Description] NVARCHAR(MAX), AverageRatingId FLOAT, SubmittedById INT, SubmittedBy VARCHAR(250), RecipeStateId INT, RecipeRatingId INT, ReviewCount INT, TweaksCount INT, PhotoCount INT, ImageName NVARCHAR(50) ) INSERT INTO @RESULT_SET_TABLE SELECT FavoriteRecipes.FavoriteRecipeId, Recipes.RecipeId, FavoriteRecipes.DateAdded, Recipes.Title, Recipes.UrlFriendlyTitle, Recipes.[Description], Recipes.AverageRatingId, Recipes.SubmittedById, COALESCE(users.DisplayName,users.UserName,Recipes.SubmittedBy) As SubmittedBy, Recipes.RecipeStateId, RecipeReviews.RecipeRatingId, COUNT(RecipeReviews.Review), COUNT(RecipeTweaks.Tweak), COUNT(Photos.PhotoId), dbo.udfGetRecipePhoto(Recipes.RecipeId) AS ImageName FROM FavoriteRecipes INNER JOIN Recipes ON FavoriteRecipes.RecipeId=Recipes.RecipeId AND Recipes.RecipeStateId <> 3 LEFT OUTER JOIN RecipeReviews ON RecipeReviews.RecipeId=Recipes.RecipeId AND RecipeReviews.ReviewedById=@UserId AND RecipeReviews.RecipeRatingId= ( SELECT MAX(RecipeReviews.RecipeRatingId) FROM RecipeReviews WHERE RecipeReviews.ReviewedById=@UserId AND RecipeReviews.RecipeId=FavoriteRecipes.RecipeId ) OR RecipeReviews.RecipeRatingId IS NULL LEFT OUTER JOIN RecipeTweaks ON RecipeTweaks.RecipeId = Recipes.RecipeId AND RecipeTweaks.TweakedById= @UserId LEFT OUTER JOIN Photos ON Photos.RecipeId = Recipes.RecipeId AND Photos.UploadedById = @UserId AND Photos.RecipeId = FavoriteRecipes.RecipeId AND Photos.PhotoTypeId = 1 LEFT OUTER JOIN users ON Recipes.SubmittedById = users.UserId WHERE FavoriteRecipes.UserId=@UserId GROUP BY FavoriteRecipes.FavoriteRecipeId, Recipes.RecipeId, FavoriteRecipes.DateAdded, Recipes.Title, Recipes.UrlFriendlyTitle, Recipes.[Description], Recipes.AverageRatingId, Recipes.SubmittedById, Recipes.SubmittedBy, Recipes.RecipeStateId, RecipeReviews.RecipeRatingId, users.DisplayName, users.UserName, Recipes.SubmittedBy; WITH SortResults AS ( SELECT ROW_NUMBER() OVER ( ORDER BY CASE WHEN @SORTDIRECTION = 't' AND @SORTORDER='a' THEN TITLE END ASC, CASE WHEN @SORTDIRECTION = 't' AND @SORTORDER='d' THEN TITLE END DESC, CASE WHEN @SORTDIRECTION = 'r' AND @SORTORDER='a' THEN AverageRatingId END ASC, CASE WHEN @SORTDIRECTION = 'r' AND @SORTORDER='d' THEN AverageRatingId END DESC, CASE WHEN @SORTDIRECTION = 'mr' AND @SORTORDER='a' THEN RecipeRatingId END ASC, CASE WHEN @SORTDIRECTION = 'mr' AND @SORTORDER='d' THEN RecipeRatingId END DESC, CASE WHEN @SORTDIRECTION = 'd' AND @SORTORDER='a' THEN DateAdded END ASC, CASE WHEN @SORTDIRECTION = 'd' AND @SORTORDER='d' THEN DateAdded END DESC ) RowNumber, FavoriteRecipeId, RecipeId, DateAdded, Title, UrlFriendlyTitle, [Description], AverageRatingId, SubmittedById, SubmittedBy, RecipeStateId, RecipeRatingId, ReviewCount, TweaksCount, PhotoCount, ImageName FROM @RESULT_SET_TABLE WHERE ((@FILTERBY = 1 AND SubmittedById= @USERID) OR ( @FILTERBY = 2 AND (SubmittedById <> @USERID OR SubmittedById IS NULL)) OR ( @FILTERBY <> 1 AND @FILTERBY <> 2)) ) SELECT RowNumber, FavoriteRecipeId, RecipeId, DateAdded, Title, UrlFriendlyTitle, [Description], AverageRatingId, SubmittedById, SubmittedBy, RecipeStateId, RecipeRatingId, ReviewCount, TweaksCount, PhotoCount, ImageName FROM SortResults WHERE RowNumber BETWEEN @ROW_START AND @ROW_END print @ROW_START print @ROW_END SELECT @RecipeCount=dbo.udfGetFavRecipesCount(@UserId) SELECT @RecipeCount AS RecipeCount SELECT COUNT(Id) as FilterCount FROM @RESULT_SET_TABLE WHERE ((@FILTERBY = 1 AND SubmittedById= @USERID) OR (@FILTERBY = 2 AND (SubmittedById <> @USERID OR SubmittedById IS NULL)) OR (@FILTERBY <> 1 AND @FILTERBY <> 2)) END

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  • Database maintenance, big binary table optimization

    - by jgemedina
    Hi i have a huge database, around 1 TB in size, most of the space is consumed by a table which stores images, the tables has right now almost 800k rows. server response time has increased, i would like to know which techniques should i use or you recomend, partitioning? o how to reorganize the table every row is accessed by the image id column, and it has its clustered index by that column, and every two days i reorganize the index and every 7 days i rebuild it, but it seems not to be working any suggestions?

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  • sequential minimal optimization C++

    - by Anton
    Hello. I want to implement the method of SVM. But the problem appeared in his training. It was originally planned to use SMO, but did not find ready-made libraries for C++. If there is a ready, then share it. Thank you in advance. The problem of finding an object in the picture (probably human)

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  • Could someone give me their two cents on this optimization strategy

    - by jimstandard
    Background: I am writing a matching script in python that will match records of a transaction in one database to names of customers in another database. The complexity is that names are not unique and can be represented multiple different ways from transaction to transaction. Rather than doing multiple queries on the database (which is pretty slow) would it be faster to get all of the records where the last name (which in this case we will say never changes) is "Smith" and then have all of those records loaded into memory as you go though each looking for matches for a specific "John Smith" using various data points. Would this be faster, is it feasible in python, and if so does anyone have any recommendations for how to do it?

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  • mysql select query optimization

    - by Saharsh Shah
    I have two table testa & testb. CREATE TABLE `testa` ( `id` INT(10) NOT NULL AUTO_INCREMENT, `name` VARCHAR(50) DEFAULT NULL, PRIMARY KEY (`id`) ); CREATE TABLE `testb` ( `id` INT(10) NOT NULL AUTO_INCREMENT, `name` VARCHAR(50) DEFAULT NULL, `aid1` INT(10) DEFAULT NULL, `aid2` INT(10) DEFAULT NULL, `aid3` INT(10) DEFAULT NULL, PRIMARY KEY (`id`) ); Currently I am running below query for retrieving all rows where id in testa table matches with any columns of aid1,aid2,aid3 in tableb. The query is retreiving acurate result but it is taking minimum 30 seconds to execute which is too much. I have also tried to optimise my query using UNION but failed to do so. SELECT a.id, a.name, b.name, b.id FROM testb b INNER JOIN testa a ON b.aid1 = a.id OR b.aid2 = a.id OR b.aid3 = a.id ; How do i optimize my query so it's total execution time is within 2-3 seconds? Thanks in advance...

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  • Optimization of SQL query regarding pair comparisons

    - by InfiniteSquirrel
    Hi, I'm working on a pair comparison site where a user loads a list of films and grades from another site. My site then picks two random movies and matches them against each other, the user selects the better of the two and a new pair is loaded. This gives a complete list of movies ordered by whichever is best. The database contains three tables; fm_film_data - this contains all imported movies fm_film_data(id int(11), imdb_id varchar(10), tmdb_id varchar(10), title varchar(255), original_title varchar(255), year year(4), director text, description text, poster_url varchar(255)) fm_films - this contains all information related to a user, what movies the user has seen, what grades the user has given, as well as information about each film's wins/losses for that user. fm_films(id int(11), user_id int(11), film_id int(11), grade int(11), wins int(11), losses int(11)) fm_log - this contains records of every duel that has occurred. fm_log(id int(11), user_id int(11), winner int(11), loser int(11)) To pick a pair to show the user, I've created a mySQL query that checks the log and picks a pair at random. SELECT pair.id1, pair.id2 FROM (SELECT part1.id AS id1, part2.id AS id2 FROM fm_films AS part1, fm_films AS part2 WHERE part1.id <> part2.id AND part1.user_id = [!!USERID!!] AND part2.user_id = [!!USERID!!]) AS pair LEFT JOIN (SELECT winner AS id1, loser AS id2 FROM fm_log WHERE fm_log.user_id = [!!USERID!!] UNION SELECT loser AS id1, winner AS id2 FROM fm_log WHERE fm_log.user_id = [!!USERID!!]) AS log ON pair.id1 = log.id1 AND pair.id2 = log.id2 WHERE log.id1 IS NULL ORDER BY RAND() LIMIT 1 This query takes some time to load, about 6 seconds in our tests with two users with about 800 grades each. I'm looking for a way to optimize this but still limit all duels to appear only once. The server runs MySQL version 5.0.90-community.

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  • ruby convert hundredth seconds to timestamp optimization

    - by Nik
    Hey! I want to convert "123456" to "00:20:34.56" where the two digits to the right of the decimal point is in hundredth of a second. So 00:00:00.99 + 00:00:00.01 = 00:00:01.00 What I have: def to_hmsc(cent) h = (cent/360000).floor cent -= h*360000 m = (cent/6000).floor cent -= m*6000 s = (cent/100).floor cent -= s*100 "#{h}:#{m}:#{s}.#{s}" end does this: to_hmsc("123456") #= "0:20:34.56" Question 1: I mean,this is ruby, I find the part ' cent -=... ' rather clunky. Can you see any way to shorten the entire process? Question 2: This has been asked a million times before, but please share whatever you've got: what's the shortest way to add leading zero to the digits. so that to_hmsc("123456") #= "00:20:34.56" Thanks!

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  • DB optimization to use it as a queue

    - by anony
    We have a table called worktable which has some columns(key(primary key), ptime, aname, status, content) we have something called producer which puts in rows in this table and we have consumer which does an order-by on the key column and fetches the first row which has status as 'pending'. The consumer does some processing on this row: 1. updates status to "processing" 2. does some processing using content 3. deletes the row we are facing contention issues when we try to run multiple consumers(probably due to the order-by which does a full table scan)... using Advanced queues would be our next step but before we go there we want to check what is the max throughput we can achieve with multiple consumers and producer on the table. What are the optimizations we can do to get the best numbers possible? Can we do an in-memory processing where a consumer fetches 1000 rows at a time processes and deletes? will that improve? What are other possibilities? partitioning of table? parallelization? Index organized tables?...

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  • empty base class optimization

    - by FredOverflow
    Two quotes from the C++ standard, §1.8: An object is a region of storage. Base class subobjects may have zero size. I don't think a region of storage can be of size zero. That would mean that some base class subobjects aren't actually objects. Opinions?

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  • NHibernate Performance Optimization | Suggestions invited!!!

    - by user336749
    Hi, I’m facing an issue with NHibernate performance and can you please suggest me some optimizations? Below mentioned is a small summary of my application architecture I have a windows service which is listening to a messaging bus. On receiving a message the service creates an object out of which a property is the received xml snippet and saves the message to the DB (uses NH). There is a WPF UI with a readonly connection to the DB, and on refresh of the UI it displays the objects on the screen. While the UI does a refresh, it retrieves the xml and deserializes it , from which the object’s properties are derived and binded to the screen. For example assume an xml XXX is received by the service, it deserializes the xml , creates the book object and save it to the DB and a property/column is SCHEMA which contains the xml snippet. The UI while refreshed searches all book objects by ID and creates the book objects out of the xml which is being saved (yes, the xml is the constructor param). Now my issue is that the refresh takes more than 2 minutes to display say 50 book objects. I analyzed it using the NHibernate profiler, and found that the time spend within the DB is negligible, however time spent to create the entities is proportionally huge(10ms:1990 ms).I guess it’s due to the fairly huge size of xml snippet and it’s deserialization. My question is, how can I improve the performance. I dispose sessions after every refresh and is not lazy loading (please note that the time spend in DB is negligible). On every refresh it’s possible that all objects are updated by some downstream systems or maybe one of them are updated.Can I implement some sort of caching mechanism in this case? Thanks in advance for any suggestions. Regards, -Mike

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  • NHibernate: Using value tables for optimization AND dynamic join

    - by Kostya
    Hi all, My situation is next: there are to entities with many-to-many relation, f.e. Products and Categories. Also, categories has hierachial structure, like a tree. There is need to select all products that depends to some concrete category with all its childs (branch). So, I use following sql statement to do that: SELECT * FROM Products p WHERE p.ID IN ( SELECT DISTINCT pc.ProductID FROM ProductsCategories pc INNER JOIN Categories c ON c.ID = pc.CategoryID WHERE c.TLeft >= 1 AND c.TRight <= 33378 ) But with big set of data this query executes very long and I found some solution to optimize it, look at here: DECLARE @CatProducts TABLE ( ProductID int NOT NULL ) INSERT INTO @CatProducts SELECT DISTINCT pc.ProductID FROM ProductsCategories pc INNER JOIN Categories c ON c.ID = pc.CategoryID WHERE c.TLeft >= 1 AND c.TRight <= 33378 SELECT * FROM Products p INNER JOIN @CatProducts cp ON cp.ProductID = p.ID This query executes very fast but I don't know how to do that with NHIbernate. Note, that I need use only ICriteria because of dynamic filtering\ordering. If some one knows a solution for that, it will be fantastic. But I'll pleasure to any suggestions of course. Thank you ahead, Kostya

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  • ILMerge - Unresolved assembly reference not allowed: System.Core

    - by Steve Michelotti
    ILMerge is a utility which allows you the merge multiple .NET assemblies into a single binary assembly more for convenient distribution. Recently we ran into problems when attempting to use ILMerge on a .NET 4 project. We received the error message: An exception occurred during merging: Unresolved assembly reference not allowed: System.Core.     at System.Compiler.Ir2md.GetAssemblyRefIndex(AssemblyNode assembly)     at System.Compiler.Ir2md.GetTypeRefIndex(TypeNode type)     at System.Compiler.Ir2md.VisitReferencedType(TypeNode type)     at System.Compiler.Ir2md.GetMemberRefIndex(Member m)     at System.Compiler.Ir2md.PopulateCustomAttributeTable()     at System.Compiler.Ir2md.SetupMetadataWriter(String debugSymbolsLocation)     at System.Compiler.Ir2md.WritePE(Module module, String debugSymbolsLocation, BinaryWriter writer)     at System.Compiler.Writer.WritePE(String location, Boolean writeDebugSymbols, Module module, Boolean delaySign, String keyFileName, String keyName)     at System.Compiler.Writer.WritePE(CompilerParameters compilerParameters, Module module)     at ILMerging.ILMerge.Merge()     at ILMerging.ILMerge.Main(String[] args) It turns out that this issue is caused by ILMerge.exe not being able to find the .NET 4 framework by default. The answer was ultimately found here. You either have to use the /lib option to point to your .NET 4 framework directory (e.g., “C:\Windows\Microsoft.NET\Framework\v4.0.30319” or “C:\Windows\Microsoft.NET\Framework64\v4.0.30319”) or just use an ILMerge.exe.config file that looks like this: 1: <configuration> 2: <startup useLegacyV2RuntimeActivationPolicy="true"> 3: <requiredRuntime safemode="true" imageVersion="v4.0.30319" version="v4.0.30319"/> 4: </startup> 5: </configuration> This was able to successfully resolve my issue.

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  • Partial specialization with reference template parameter fails to compile in VS2005

    - by Blair Holloway
    I have code that boils down to the following: template struct Foo {}; template & I struct FooBar {}; //////// template struct Baz {}; template & I struct Baz< FooBar { static void func(FooBar& value); }; //////// struct MyStruct { static const Foo s_floatFoo; }; // Elsewhere: const Foo MyStruct::s_floatFoo; void callBaz() { typedef FooBar FloatFooBar; FloatFooBar myFloatFooBar; Baz::func(myFloatFooBar); } This compiles successfully under GCC, however, under VS2005, I get: error C2039: 'func' : is not a member of 'Baz' with [ T=FloatFooBar ] error C3861: 'func': identifier not found However, if I change const Foo<T>& I to const Foo<T>* I (passing I by pointer rather than by reference), and defining FloatFooBar as: typedef FooBar FloatFooBar; Both GCC and VS2005 are happy. What's going on? Is this some kind of subtle template substitution failure that VS2005 is handling differently to GCC, or a compiler bug? (The strangest thing: I thought I had the above code working in VS2005 earlier this morning. But that was before my morning coffee. I'm now not entirely certain I wasn't under some sort of caffeine-craving-induced delirium...)

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  • GCC emits extra code for boost::shared_ptr dereference

    - by Checkers
    I have the following code: #include <boost/shared_ptr.hpp> struct Foo { int a; }; static int A; void func_shared(const boost::shared_ptr<Foo> &foo) { A = foo->a; } void func_raw(Foo * const foo) { A = foo->a; } I thought the compiler would create identical code, but for shared_ptr version an extra seemingly redundant instruction is emitted. Disassembly of section .text: 00000000 <func_raw(Foo*)>: 0: 55 push ebp 1: 89 e5 mov ebp,esp 3: 8b 45 08 mov eax,DWORD PTR [ebp+8] 6: 5d pop ebp 7: 8b 00 mov eax,DWORD PTR [eax] 9: a3 00 00 00 00 mov ds:0x0,eax e: c3 ret f: 90 nop 00000010 <func_shared(boost::shared_ptr<Foo> const&)>: 10: 55 push ebp 11: 89 e5 mov ebp,esp 13: 8b 45 08 mov eax,DWORD PTR [ebp+8] 16: 5d pop ebp 17: 8b 00 mov eax,DWORD PTR [eax] 19: 8b 00 mov eax,DWORD PTR [eax] 1b: a3 00 00 00 00 mov ds:0x0,eax 20: c3 ret I'm just curious, is this necessary, or it is just an optimizer's shortcoming? Compiling with g++ 4.1.2, -O3 -NDEBUG.

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  • Is there a standard lexer/parser tool for Python?

    - by Salim Fadhley
    A volunteer job requires us to convert a large number of LaTeX documents into ePub format. It's a series of open-source fiction book which has so far only been produced only on paper via a print on demand service. We'd like to be able to offer the book to users of book-reader devices (such as Kindle) which require the ePub format for best results. Fortunately, ePub is a very simple format, however there's no trivial way for LaTeX to produce the XHTML outut required. We experimented with alternative LaTeX compilers (e.g. plastex) but in the end we figured that it would probably be a lot easier to simply write our own compiler which understands a tiny subset of the LaTeX language and compiles directly to XHTML / ePub. Previously I used a tool on Windows called GOLD. This allowed me to go directly from BNF grammars to a stub parser. It also alllowed me to implement the parser in any language I liked. (I'd choose Python). This product has to work on Linux, so I'm wondering if there's an equivalent toolchain that works as well under Ubutnu / Eclipse / Python. The idea is that we will take the grammar of TeX and just implement a teeny subset of that, but we do not want to spend a huge amount of time worrying about grammar and parsing. A parser generator would obviously save us a great deal of time. Sal UPDATE 1: Bonus marks for a solution with excellent documentation or tutorials.

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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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  • Recognizing terminals in a CFG production previously not defined as tokens.

    - by kmels
    I'm making a generator of LL(1) parsers, my input is a CoCo/R language specification. I've already got a Scanner generator for that input. Suppose I've got the following specification: COMPILER 1. CHARACTERS digit="0123456789". TOKENS number = digit{digit}. decnumber = digit{digit}"."digit{digit}. PRODUCTIONS Expression = Term{"+"Term|"-"Term}. Term = Factor{"*"Factor|"/"Factor}. Factor = ["-"](Number|"("Expression")"). Number = (number|decnumber). END 1. So, if the parser generated by this grammar receives a word "1+1", it'd be accepted i.e. a parse tree would be found. My question is, the character "+" was never defined in a token, but it appears in the non-terminal "Expression". How should my generated Scanner recognize it? It would not recognize it as a token. Is this a valid input then? Should I add this terminal in TOKENS and then consider an error routine for a Scanner for it to skip it? How does usual language specifications handle this?

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  • Raw types and subtyping

    - by Dmitrii
    We have generic class SomeClass<T>{ } We can write the line: SomeClass s= new SomeClass<String>(); It's ok, because raw type is supertype for generic type. But SomeClass<String> s= new SomeClass(); is correct to. Why is it correct? I thought that type erasure was before type checking, but it's wrong. From Hacker's Guide to Javac When the Java compiler is invoked with default compile policy it performs the following passes: parse: Reads a set of *.java source files and maps the resulting token sequence into AST-Nodes. enter: Enters symbols for the definitions into the symbol table. process annotations: If Requested, processes annotations found in the specified compilation units. attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding. flow: Performs data ow analysis on the trees from the previous step. This includes checks for assignments and reachability. desugar: Rewrites the AST and translates away some syntactic sugar. generate: Generates Source Files or Class Files. Generic is syntax sugar, hence type erasure invoked at 6 pass, after type checking, which invoked at 4 pass. I'm confused.

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  • Is there really such a thing as a char or short in modern programming?

    - by Dean P
    Howdy all, I've been learning to program for a Mac over the past few months (I have experience in other languages). Obviously that has meant learning the Objective C language and thus the plainer C it is predicated on. So I have stumbles on this quote, which refers to the C/C++ language in general, not just the Mac platform. With C and C++ prefer use of int over char and short. The main reason behind this is that C and C++ perform arithmetic operations and parameter passing at integer level, If you have an integer value that can fit in a byte, you should still consider using an int to hold the number. If you use a char, the compiler will first convert the values into integer, perform the operations and then convert back the result to char. So my question, is this the case in the Mac Desktop and IPhone OS environments? I understand when talking about theses environments we're actually talking about 3-4 different architectures (PPC, i386, Arm and the A4 Arm variant) so there may not be a single answer. Nevertheless does the general principle hold that in modern 32 bit / 64 bit systems using 1-2 byte variables that don't align with the machine's natural 4 byte words doesn't provide much of the efficiency we may expect. For instance, a plain old C-Array of 100,000 chars is smaller than the same 100,000 ints by a factor of four, but if during an enumeration, reading out each index involves a cast/boxing/unboxing of sorts, will we see overall lower 'performance' despite the saved memory overhead?

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