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  • Recommended textbook for machine-level programming?

    - by Norman Ramsey
    I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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  • Exploding by Array of Delimiters

    - by JoeC
    Is there any way to explode() using an array of delimiters? PHP Manual: array explode ( string $delimiter , string $string [, int $limit ] ) Instead of using string $delimiter is there any way to use array $delimiter without affecting performance too much?

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  • Writing user stories for internal technical tasks

    - by John Nolan
    I am attempting to manage my projects a little better so I am looking at attempting to apply some of (eventually all) the features of scrum. Looking at user stories specifically the high level format seems to be: As a User I can Feature Description or Artifact is Doing Something How would I write "Upgrade the Database"? Is it simply Upgrade the Database? I think I am being thrown off as there is no specific actor/customer and that the customer is the IT department.

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  • Conventions for modelling c programs.

    - by Hassan Syed
    I'm working with a source base written almost entirely in straight-c (nginx). It does, however, make use of rich high level programming techniques such as compile-time metaprogramming, and OOP - including run-time dispatch. I want to draw ER diagrams, UML class diagrams and UML sequence diagrams. However to have a clean mapping between the two, consistent conventions must be applied. So, I am hopping someone has some references to material that establishes or applies such conventions to similar style c-code.

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  • Reasons for Parallel Extensions working slowly

    - by darja
    I am trying to make my calculating application faster by using Parallel Extensions. I am new in it, so I have just replaced the main foreach loop with Parallel.ForEach. But calculating became more slow. What can be common reasons for decreasing performance of parallel extensions? Thanks

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  • Concise way to getattr() and use it if not None in Python

    - by MTsoul
    I am finding myself doing the following a bit too often: attr = getattr(obj, 'attr', None) if attr is not None: attr() # Do something, either attr(), or func(attr), or whatever else: # Do something else Is there a more pythonic way of writing that? Is this better? (At least not in performance, IMO.) try: obj.attr() # or whatever except AttributeError: # Do something else

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  • Best approach to write huge xml data to file?

    - by Kayes
    Hi. I'm currently exporting a database table with huge data (100000+ records) into an xml file using XmlTextWriter class and I'm writing directly to a file on the physical drive. _XmlTextWriterObject = new XmlTextWriter(_xmlFilePath, null); While my code runs ok, my question is that is it the best approach? Or should I write the whole xml in memory stream first and then write the xml document in physical file from memory stream? And what are the effects on memory/ performance in both cases?

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  • Detecting I/O errors in a NON BLOCKING SOCKET

    - by ripunjay-tripathi-gmail-com
    I am writing a client - server system in which I used NON-BLOCKING sockets. My problem is to detect error { while performing send() or write() } that may occur while data transfer. Example lets say, while the data is being transferred the peer crashes. Another case there is some network problem, something like wire unplugged etc. As of now, I am using a high level ACK, that peer sends after receiving the complete data. Ripunjay Tripathi

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  • Is it possible to implement Separated Interface in PHP?

    - by sunwukung
    I recently asked a question regarding the resolution of dependencies between Unit of Work and Data Mapper classes: http://stackoverflow.com/questions/3012657/dependency-injection-and-unit-of-work-pattern - (which was answered by Gabor de Mooij - thx) In PoEAA, Martin Fowler suggests using Separated Interface to manage these dependencies. My question is simple - is it actually possible to implement this pattern in PHP, or is it specific to Java interfaces? I've searched high and low and it's hard to find references to this pattern anywhere outside of PoEAA.

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  • Which audio playback technology do I need for this?

    - by mystify
    I have trouble choosing the right audio playback technology. There's a ton of technologies to use on the iPhone, it's so confusing. What I need to do is this: start playing short sounds ranging between 0.1 and 2 seconds high quality playback, no crackle (I heard some of the iPhone audio playback technologies do a crackle sound on start or end, which is bad!) ability to start playback of a sound, while there's already another one playing right now (two, three or more sounds at the same time) What would you suggest here, and why? Thanks :-)

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  • Mysterious constraints problem with SQL Server 2000

    - by Ramon
    Hi all I'm getting the following error from a VB NET web application written in VS 2003, on framework 1.1. The web app is running on Windows Server 2000, IIS 5, and is reading from a SQL server 2000 database running on the same machine. System.Data.ConstraintException: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. at System.Data.DataSet.FailedEnableConstraints() at System.Data.DataSet.EnableConstraints() at System.Data.DataSet.set_EnforceConstraints(Boolean value) at System.Data.DataTable.EndLoadData() at System.Data.Common.DbDataAdapter.FillFromReader(Object data, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillFromCommand(Object data, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) The problem appears when the web app is under a high load. The system runs fine when volume is low, but when the number of requests becomes high, the system starts rejecting incoming requests with the above exception message. Once the problem appears, very few requests actually make it through and get processed normally, about 2 in every 30. The vast majority of requests fail, until a SQL Server restart or IIS reset is performed. The system then start processing requests normally, and after some time it starts throwing the same error. The error occurs when a data adapter runs the Fill() method against a SELECT statement, to populate a strongly-typed dataset. It appears that the dataset does not like the data it is given and throws this exception. This error occurs on various SELECT statements, acting on different tables. I have regenerated the dataset and checked the relevant constraints, as well as the table from which the data is read. Both the dataset definition and the data in the table are fine. Admittedly, the hardware running both the web app and SQL Server 2000 is seriously outdated, considering the numbers of incoming requests it currently receives. The amount of RAM consumed by SQL Server is dynamically allocated, and at peak times SQL Server can consume up to 2.8 GB out of a total of 3.5 GB on the server. At first I suspected some sort of index or database corruption, but after running DBCC CHECKDB, no errors were found in the database. So now I'm wondering whether this error is a result of the hardware limitations of the system. Is it possible for SQL Server to somehow mess up the data it's supposed to pass to the dataset, resulting in constraint violation due to, say, data type/length mismatch? I tried accessing the RowError messages of the data rows in the retrieved dataset tables but I kept getting empty strings. I know that HasErrors = true for the datatables in question. I have not set the EnableConstraints = false, and I don't want to do that. Thanks in advance. Ray

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  • When should I use temporary variables?

    - by Kyle
    Specifically, I'm wondering which of these I should write: shared_ptr<GuiContextMenu> subMenu = items[j].subMenu.lock(); if (subMenu) subMenu->setVisible(false); or: if (items[j].subMenu.lock() items[j].subMenu.lock()->setVisible(false); I am not required to follow any style guidelines. After optimization, I don't think either choice makes a difference in performance. What is generally the preferred style and why?

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  • WCF v.s. legacy ASP.Net Web Services

    - by George2
    Duplicate: although this is a good discussion, this is a duplicate of Web Services — WCF vs. Standard. Please consider adding any new information to the earlier question and closing this one. Could anyone recommend me some documents to describe why WCF is better than legacy ASP.Net web services? I am especially interested in performance and security. Thanks!

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  • How to convert pdf to png ?

    - by lisyqiao
    ( www.pdftopng.net )*PDF to PNG*Converter is the professional software that can convert PDF to PNG with high quality and fast speed. Besides, Free PDF to PNG can convert PNG to the other images like PDF to JPG, PDF to GIF, PDF to TIFF, PDF to BMP and so on. What's more, PDF to PNG can customize your output settings including output type, output color and page range etc.

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