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  • determine parity of a bit representation of a number in MIPS

    - by Hristo
    Is there some instruction in MIPS that will determine the parity of a certain bit representation? I know to determine whether a "number" has an even parity or an odd parity is to XOR the individual bits of the binary representation together, but that seems computationally-intensive for a set of MIPS instructions... and I need to do this as quick as possible. Also, the number I'm working in is represented in Grey Code... just to throw that in there. So is there some pseudo-instruction in MIPS to determine the parity of a "number" or do I have to do it by hand? If there is no MIPS instruction, which it seems very unlikely to be, any advice on how to do it by hand? Thanks, Hristo follow-up: I found a optimization, but my implementation isn't working. unsigned int v; // 32-bit word v ^= v >> 1; v ^= v >> 2; v = (v & 0x11111111U) * 0x11111111U; return (v >> 28) & 1;

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  • NETCF - Optimized Repaint (onPaint)

    - by Nullstr1ng
    Hi Guys, I want to ask for suggestions on how to optimize a repaint in Compact Framework? GetHashCode() didn't help because it always return a different hash code. Anyway, I have a program which you can drag and resize an object in run time. This object is a transparent object and it has a PNG image which also dynamically resize relative to object client size. Though I noticed, (e.g. I have 4 transparent object and I'm dragging or resizing one) all 4 of them triggers OnPaintBackground even if the 3 are not moving. Another one when am just tapping on the one object .. it sill triggers onPaintBacground(). Anyway, I don't have a problem when this events get triggered. What I like to do is optimization and that means I only have to repaint the object when it's necessary. Can you guys please give a suggestions? here's my pseudo C# code Bitmap _backBuff; onResize() { if(_backBuff != null) _backBuff.Dispose(); _backBuff = new Bitmap(ClientSize.Width, ClientSize.Height); Invalidate(); } onPaintBackground(e) /*have to use onPaintBackground because MSDN said it's faster*/ { using(Graphics g = Graphics.FromImage(_backBuff)) { g.Clear(Color.Black); // draw background ....some interface calling here ....and paint the background // draw alpha PNG .. get hDc .. paint PNG .. release hDc } e.Graphics.DrawImage(_backBuff,0,0); } Thanks in advance.

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  • SVM Classification - minimum number of input sets for each class

    - by Amol Joshi
    Im trying to build an app to detect images which are advertisements from the webpages. Once I detect those Ill not be allowing those to be displayed on the client side. From the help that I got here in stackoverflow, I thought SVM is the best approach to my aim. So, I have coded SVM and an SMO myself. The dataset which I have got from UCI data repository has 3280 instances ( Link to Dataset- http://archive.ics.uci.edu/ml/datasets/Internet+Advertisements )where around 400 of them are from class representing Advertisement images and rest of them representing non-advertisement images. Right now Im taking the first 2800 input sets and training the SVM. But after looking at the accuracy rate I realised that most of those 2800 input sets are from non-advertisement image class. So Im getting very good accuracy for that class. So what can I do here? About how many input set shall I give to SVM to train and how many of them for each class? Thanks. Cheers. ( Basically made a new question because the context was different from my previous question. http://stackoverflow.com/questions/1991113/optimization-of-neural-network-input-data )

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  • Android ndk-build command does nothing

    - by James
    I have a similar question to that posted here: Android NDK: why ndk-build doesn't generate .so file and a new libs folder in Eclipse? ...though I am running Windows 7, not Mac os. Essentially the ndk-build command is run, gives no error but doesn't create an .so file (also, since I'm on windows this should create a .dll and not an .so?). I tried running the command from the root, jni, src folders etc. but got the same result; cmd just returns to the prompter after a few seconds. I ran it again from the jni folder with NDK_LOG=1 parameter to see what was happening. Here is a portion of the transcript of the log results after running ndk-build in the jni folder (after it successfully identified the platform, etc.)... Android NDK: Looking for jni/Android.mk in /workspace/NdkFooActivity/jni Android NDK: Looking for jni/Android.mk in /workspace/NdkFooActivity Android NDK: Found it ! Android NDK: Found project path: /workspace/NdkFooActivity Android NDK: Ouput path: /workspace/NdkFooActivity/obj Android NDK: Parsing /cygdrive/c/android-ndk-r8/build/core/default-application.mk Android NDK: Found APP_PLATFORM=android-15 in /workspace/NdkFooActivity/project.properties Android NDK: Application local targets unknown platform 'android-15' Android NDK: Switching to android-14 Android NDK: Using build script /workspace/NdkFooActivity/jni/Android.mk Android NDK: Application 'local' is not debuggable Android NDK: Selecting release optimization mode (app is not debuggable) Android NDK: Adding import directory: /cygdrive/c/android-ndk-r8/sources Android NDK: Building application 'local' for ABI 'armeabi' Android NDK: Using target toolchain 'arm-linux-androideabi-4.4.3' for 'armeabi' ABI Android NDK: Looking for imported module with tag 'cxx-stl/system' Android NDK: Probing /cygdrive/c/android-ndk-r8/sources/cxx-stl/system/Android.mk Android NDK: Found in /cygdrive/c/android-ndk-r8/sources/cxx-stl/system Android NDK: Cygwin dependency file conversion script: ...after which point it just runs the script mentioned in the last line, then terminates. Any ideas? Thanks!

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  • Axis2 webservice (aar archive) properties file

    - by XpiritO
    Hi there, guys. I'm currently developing a set of SOAP webservices over Axis2, deployed over a clustered WebLogic 10.3.2 environment. My webservices use some user settings that I want to be editable without the need for recompiling and regenerating the AAR archive. With this in mind, I chose to put them into a properties file that is loaded and consumed in runtime. Unfortunately, I'm having some questions about this: As far as I know, to achieve what I want, the only option is to put the properties file into the ../axis2/WEB-INF/classes directory of each one of the deployments (on each WebLogic instance) I currently have on my clustered configuration, and then load the file, as follows (or equivalent, this has not been verified for optimization): InputStreamReader fMainProp = new InputStreamReader(this.getClass().getResourceAsStream("myfile.properties")); Properties mainProp = new Properties(); mainProp.load(fMainProp); This is not as practical as I wanted it to be, because each time I want to alter some setting on the properties file, I have to edit each one of the files (deployed over different WebLogic instances) and there is a high probability of modifying one of these files without modifying the others. What I would like to know is if there is any (better) alternative to accomplish what I want, minimizing the potential conflict of configuration that is created by distributing and replicating the properties file through multiple WebLogic instances.

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  • How to force two process to run on the same CPU?

    - by kovan
    Context: I'm programming a software system that consists of multiple processes. It is programmed in C++ under Linux. and they communicate among them using Linux shared memory. Usually, in software development, is in the final stage when the performance optimization is made. Here I came to a big problem. The software has high performance requirements, but in machines with 4 or 8 CPU cores (usually with more than one CPU), it was only able to use 3 cores, thus wasting 25% of the CPU power in the first ones, and more than 60% in the second ones. After many research, and having discarded mutex and lock contention, I found out that the time was being wasted on shmdt/shmat calls (detach and attach to shared memory segments). After some more research, I found out that these CPUs, which usually are AMD Opteron and Intel Xeon, use a memory system called NUMA, which basically means that each processor has its fast, "local memory", and accessing memory from other CPUs is expensive. After doing some tests, the problem seems to be that the software is designed so that, basically, any process can pass shared memory segments to any other process, and to any thread in them. This seems to kill performance, as process are constantly accessing memory from other processes. Question: Now, the question is, is there any way to force pairs of processes to execute in the same CPU?. I don't mean to force them to execute always in the same processor, as I don't care in which one they are executed, altough that would do the job. Ideally, there would be a way to tell the kernel: If you schedule this process in one processor, you must also schedule this "brother" process (which is the process with which it communicates through shared memory) in that same processor, so that performance is not penalized.

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  • Optimized graph drawing for the web

    - by Andreas Petersson
    Having seen some suggestions for graphs, I wonder what's the optimum for my problem. I want to render a directed graph to a servlet/picture that is displayed in the browser. There should be some kind of optimization of position. No dependency to Swing would be preferred. Algorithms are not important, since the structure of the graph is determined by business logic. It would be desired to be able add labels to edges as well. it would be optimal if i can serve this as png/svg. Which library/service would you recommend? clarifications: 1) The question is all about Graphs - like Directed Acyclic Graph - NOT - Charts. 2) flot, Google Charts - cannot plot graphs, only charts, or have i missed something? 3) no i do not need interactivity 4) graphviz would be nice, but the grappa java library is quite outdated and is built upon swing/awt. while it may be theoretically possible to render swing to images, it would not be my favorite way to to so in a server-app. 5) it would be fine to use an online service where the images are not hosted locally. edit: added links to Wikipedia to clarify graph/chart term

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  • Is this question too hard for a seasoned C++ architect?

    - by Monomer
    Background Information We're looking to hire a seasoned C++ architect (10+years dev, of which at least 6years must be C++ ) for a high frequency trading platform. Job advert says STL, Boost proficiency is a must with preferences to modern uses of C++. The company I work for is a Fortune 500 IB (aka finance industry), it requires passes in all the standard SHL tests (numeric, vocab, spatial etc) before interviews can commence. Everyone on the team was given the task of coming up with one question to ask the candidates during a written/typed test, please note this is the second test provided to the candidates, the first being Advanced IKM C++ test, done in the offices supervised and without internet access. People passing that do the second test. After roughly 70 candidates, my question has been determined to be statistically the worst performing - aka least number of people attempted it, furthermore even less people were able to give meaningful answers. Please note, the second test is not timed, the candidate can literally take as long as they like (we've had one person take roughly 10.5hrs) My question to SO is this, after SHL and IKM adv c++ tests, backed up with at least 6+ years C++ development experience, is it still ok not to be able to even comment about let alone come up with some loose strategy for solving the following question. The Question There is a class C with methods foo, boo, boo_and_foo and foo_and_boo. Each method takes i,j,k and l clock cycles respectively, where i < j, k < i+j and l < i+j. class C { public: int foo() {...} int boo() {...} int boo_and_foo() {...} int foo_and_boo() {...} }; In code one might write: C c; . . int i = c.foo() + c.boo(); But it would be better to have: int i = c.foo_and_boo(); What changes or techniques could one make to the definition of C, that would allow similar syntax of the original usage, but instead have the compiler generate the latter. Note that foo and boo are not commutative. Possible Solution We were basically looking for an expression templates based approach, and were willing to give marks to anyone who had even hinted or used the phrase or related terminology. We got only two people that used the wording, but weren't able to properly describe how they accomplish the task in detail. We use such techniques all over the place, due to the use of various mathematical operators for matrix and vector based calculations, for example to decide when to use IPP or hand woven implementations at compile time for a particular architecture and many other things. The particular area of software development requires microsecond response times. I believe could/should be able to teach a junior such techniques, but given the assumed caliber of candidates I expected a little more. Is this really a difficult question? Should it be removed? Or are we just not seeing the right candidates?

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  • Worse is better. Is there an example?

    - by J.F. Sebastian
    Is there a widely-used algorithm that has time complexity worse than that of another known algorithm but it is a better choice in all practical situations (worse complexity but better otherwise)? An acceptable answer might be in a form: There are algorithms A and B that have O(N**2) and O(N) time complexity correspondingly, but B has such a big constant that it has no advantages over A for inputs less then a number of atoms in the Universe. Examples highlights from the answers: Simplex algorithm -- worst-case is exponential time -- vs. known polynomial-time algorithms for convex optimization problems. A naive median of medians algorithm -- worst-case O(N**2) vs. known O(N) algorithm. Backtracking regex engines -- worst-case exponential vs. O(N) Thompson NFA -based engines. All these examples exploit worst-case vs. average scenarios. Are there examples that do not rely on the difference between the worst case vs. average case scenario? Related: The Rise of ``Worse is Better''. (For the purpose of this question the "Worse is Better" phrase is used in a narrower (namely -- algorithmic time-complexity) sense than in the article) Python's Design Philosophy: The ABC group strived for perfection. For example, they used tree-based data structure algorithms that were proven to be optimal for asymptotically large collections (but were not so great for small collections). This example would be the answer if there were no computers capable of storing these large collections (in other words large is not large enough in this case). Coppersmith–Winograd algorithm for square matrix multiplication is a good example (it is the fastest (2008) but it is inferior to worse algorithms). Any others? From the wikipedia article: "It is not used in practice because it only provides an advantage for matrices so large that they cannot be processed by modern hardware (Robinson 2005)."

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  • Which key:value store to use with Python?

    - by Kurt
    So I'm looking at various key:value (where value is either strictly a single value or possibly an object) stores for use with Python, and have found a few promising ones. I have no specific requirement as of yet because I am in the evaluation phase. I'm looking for what's good, what's bad, what are the corner cases these things handle well or don't, etc. I'm sure some of you have already tried them out so I'd love to hear your findings/problems/etc. on the various key:value stores with Python. I'm looking primarily at: memcached - http://www.danga.com/memcached/ python clients: http://pypi.python.org/pypi/python-memcached/1.40 http://www.tummy.com/Community/software/python-memcached/ CouchDB - http://couchdb.apache.org/ python clients: http://code.google.com/p/couchdb-python/ Tokyo Tyrant - http://1978th.net/tokyotyrant/ python clients: http://code.google.com/p/pytyrant/ Lightcloud - http://opensource.plurk.com/LightCloud/ Based on Tokyo Tyrant, written in Python Redis - http://code.google.com/p/redis/ python clients: http://pypi.python.org/pypi/txredis/0.1.1 MemcacheDB - http://memcachedb.org/ So I started benchmarking (simply inserting keys and reading them) using a simple count to generate numeric keys and a value of "A short string of text": memcached: CentOS 5.3/python-2.4.3-24.el5_3.6, libevent 1.4.12-stable, memcached 1.4.2 with default settings, 1 gig memory, 14,000 inserts per second, 16,000 seconds to read. No real optimization, nice. memcachedb claims on the order of 17,000 to 23,000 inserts per second, 44,000 to 64,000 reads per second. I'm also wondering how the others stack up speed wise.

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  • How to keep unreachable code?

    - by Gabriel
    I'd like to write a function that would have some optional code to execute or not depending on user settings. The function is cpu-intensive and having ifs in it would be slow since the branch predictor is not that good. My idea is making a copy in memory of the function and replace NOPs with jumps when I don't want to execute some code. My working example goes like this: int Test() { int x = 2; for (int i=0 ; i<10 ; i++) { x *= 2; __asm {NOP}; // to skip it replace this __asm {NOP}; // by JMP 2 (after the goto) x *= 2; // Op to skip or not x *= 2; } return x; } In my test's main, I copy this function into a newly allocated executable memory and replace the NOPs by a JMP 2 so that the following x *= 2 is not executed. The problem is that I would have to change the JMP operand every time I change the code to be skipped. An alternative that would fix this problem would be: __asm {NOP}; // to skip it replace this __asm {NOP}; // by JMP 2 (after the goto) goto dont_do_it; x *= 2; // Op to skip or not dont_do_it: x *= 2; This way, as a goto uses 2 bytes of binary, I would be able to replace the NOPs by a fixed JMP of alway 2 in order to skip the goto. Unfortunately, in full optimization mode, the goto and the x*=2 are removed because they are unreachable at compilation time. Hence the need to keep that dead code.

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  • Does replace into have a where clause?

    - by Lajos Arpad
    I'm writing an application and I'm using MySQL as DBMS, we are downloading property offers and there were some performance issues. The old architecture looked like this: A property is updated. If the number of affected rows is not 1, then the update is not considered successful, elseway the update query solves our problem. If the update was not successful, and the number of affected rows is more than 1, we have duplicates and we delete all of them. After we deleted duplicates if needed if the update was not successful, an insert happens. This architecture was working well, but there were some speed issues, because properties are deleted if they were not updated for 15 days. Theoretically the main problem is deleting properties, because some properties are alive for months and the indexes are very far from each other (we are talking about 500, 000+ properties). Our host told me to use replace into instead of deleting properties and all deprecated properties should be considered as DEAD. I've done this, but problems started to occur because of syntax error and I couldn't find anywhere an example of replace into with a where clause (I'd like to replace a DEAD property with the new property instead of deleting the old property and insert a new to assure optimization). My query looked like this: replace into table_name(column1, ..., columnn) values(value1, ..., valuen) where ID = idValue Of course, I've calculated idValue and handled everything but I had a syntax error. I would like to know if I'm wrong and there is a where clause for replace into. I've found an alternative solution, which is even better than replace into (using simply an update query) because deletes are happening behind the curtains if I use replace into, but I would like to know if I'm wrong when I say that replace into doesn't have a where clause. For more reference, see this link: http://dev.mysql.com/doc/refman/5.0/en/replace.html Thank you for your answers in advance, Lajos Árpád

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  • P6 Architecture - Register renaming aside, does the limited user registers result in more ops spent

    - by mrjoltcola
    I'm studying JIT design with regard to dynamic languages VM implementation. I haven't done much Assembly since the 8086/8088 days, just a little here or there, so be nice if I'm out of sorts. As I understand it, the x86 (IA-32) architecture still has the same basic limited register set today that it always did, but the internal register count has grown tremendously, but these internal registers are not generally available and are used with register renaming to achieve parallel pipelining of code that otherwise could not be parallelizable. I understand this optimization pretty well, but my feeling is, while these optimizations help in overall throughput and for parallel algorithms, the limited register set we are still stuck with results in more register spilling overhead such that if x86 had double, or quadruple the registers available to us, there may be significantly less push/pop opcodes in a typical instruction stream? Or are there other processor optmizations that also optimize this away that I am unaware of? Basically if I've a unit of code that has 4 registers to work with for integer work, but my unit has a dozen variables, I've got potentially a push/pop for every 2 or so instructions. Any references to studies, or better yet, personal experiences?

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  • What are the primitive Forth operators?

    - by Barry Brown
    I'm interested in implementing a Forth system, just so I can get some experience building a simple VM and runtime. When starting in Forth, one typically learns about the stack and its operators (DROP, DUP, SWAP, etc.) first, so it's natural to think of these as being among the primitive operators. But they're not. Each of them can be broken down into operators that directly manipulate memory and the stack pointers. Later one learns about store (!) and fetch (@) which can be used to implement DUP, SWAP, and so forth (ha!). So what are the primitive operators? Which ones must be implemented directly in the runtime environment from which all others can be built? I'm not interested in high-performance; I want something that I (and others) can learn from. Operator optimization can come later. (Yes, I'm aware that I can start with a Turing machine and go from there. That's a bit extreme.) Edit: What I'm aiming for is akin to bootstrapping an operating system or a new compiler. What do I need do implement, at minimum, so that I can construct the rest of the system out of those primitive building blocks? I won't implement this on bare hardware; as an educational exercise, I'd write my own minimal VM.

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  • Reporting System architecture for better performance

    - by pauloya
    Hi, We have a product that runs Sql Server Express 2005 and uses mainly ASP.NET. The database has around 200 tables, with a few (4 or 5) that can grow from 300 to 5000 rows per day and keep a history of 5 years, so they can grow to have 10 million rows. We have built a reporting platform, that allows customers to build reports based on templates, fields and filters. We face performance problems almost since the beginning, we try to keep reports display under 10 seconds but some of them go up to 25 seconds (specially on those customers with long history). We keep checking indexes and trying to improve the queries but we get the feeling that there's only so much we can do. Off course the fact that the queries are generated dynamically doesn't help with the optimization. We also added a few tables that keep redundant data, but then we have the added problem of maintaining this data up to date, and also Sql Express has a limit on the size of databases. We are now facing a point where we have to decide if we want to give up real time reports, or maybe cut the history to be able to have better performance. I would like to ask what is the recommended approach for this kind of systems. Also, should we start looking for third party tools/platforms? I know OLAP can be an option but can we make it work on Sql Server Express, or at least with a license that is cheap enough to distribute to thousands of deployments? Thanks

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  • How do people know so much about programming?

    - by Luciano
    I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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  • How to localize an app on Google App Engine?

    - by Petri Pennanen
    What options are there for localizing an app on Google App Engine? How do you do it using Webapp, Django, web2py or [insert framework here]. 1. Readable URLs and entity key names Readable URLs are good for usability and search engine optimization (Stack Overflow is a good example on how to do it). On Google App Engine, key based queries are recommended for performance reasons. It follows that it is good practice to use the entity key name in the URL, so that the entity can be fetched from the datastore as quickly as possible. Currently I use the function below to create key names: import re import unicodedata def urlify(unicode_string): """Translates latin1 unicode strings to url friendly ASCII. Converts accented latin1 characters to their non-accented ASCII counterparts, converts to lowercase, converts spaces to hyphens and removes all characters that are not alphanumeric ASCII. Arguments unicode_string: Unicode encoded string. Returns String consisting of alphanumeric (ASCII) characters and hyphens. """ str = unicodedata.normalize('NFKD', unicode_string).encode('ASCII', 'ignore') str = re.sub('[^\w\s-]', '', str).strip().lower() return re.sub('[-\s]+', '-', str) This works fine for English and Swedish, however it will fail for non-western scripts and remove letters from some western ones (like Norwegian and Danish with their œ and ø). Can anyone suggest a method that works with more languages? 2. Translating templates Does Django internationalization and localization work on Google App Engine? Are there any extra steps that must be performed? Is it possible to use Django i18n and l10n for Django templates while using Webapp? The Jinja2 template language provides integration with Babel. How well does this work, in your experience? What options are avilable for your chosen template language? 3. Translated datastore content When serving content from (or storing it to) the datastore: Is there a better way than getting the *accept_language* parameter from the HTTP request and matching this with a language property that you have set with each entity?

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  • What are best practices for managing related Cabal packages?

    - by Norman Ramsey
    I'm working on a dataflow-based optimization library written in Haskell. It now seems likely that the library is going to have to be split into two pieces: A core piece with minimal build dependencies; call it hoopl-core. A full piece, call it hoopl, which may have extra dependencies on packages like a prettyprinter, QuickCheck, and so on. The idea is that the Glasgow Haskell Compiler will depend only on hoopl-core, so that it won't be too difficult to bootstrap the compiler. Other compilers will get the extra goodies in hoopl. Package hoopl will depend on hoopl-core. The Debian package tools can build multiple packages from a single source tree. Unfortunately Cabal has not yet reached that level of sophistication. But there must be other library or application designers out there who have similar issues (e.g., one package for a core library, another for a command-line interface, another for a GUI interface). What are current best practices for building and managing multiple related Haskell packages using Cabal?

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  • Where to find algorithms for standard math functions?

    - by dsimcha
    I'm looking to submit a patch to the D programming language standard library that will allow much of std.math to be evaluated at compile time using the compile-time function evaluation facilities of the language. Compile-time function evaluation has several limitations, the most important ones being: You can't use assembly language. You can't call C code or code for which the source is otherwise unavailable. Several std.math functions violate these and compile-time versions need to be written. Where can I get information on good algorithms for computing things such as logarithms, exponents, powers, and trig functions? I prefer just high level descriptions of algorithms to actual code, for two reasons: To avoid legal ambiguity and the need to make my code look "different enough" from the source to make sure I own the copyright. I want simple, portable algorithms. I don't care about micro-optimization as long as they're at least asymptotically efficient. Edit: D's compile time function evaluation model allows floating point results computed at compile time to differ from those computed at runtime anyhow, so I don't care if my compile-time algorithms don't give exactly the same result as the runtime version as long as they aren't less accurate to a practically significant extent.

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  • cl.exe Difference in object files when /E output is the same and flags are the same

    - by madiyaan damha
    Hello: I am using Visual Studio 2005's cl.exe compiler. I call it with a bunch of /I /D and some compilation/optimization flags (example: /Ehsc). I have two compilation scripts, and both differ only in the /I flags (include directories are different). All other flags are the same. These scripts produce different object files (and not just a timestamp difference as noted below). The strange thing is that the /E output of both scripts is the same. That means that the include files are not causing the difference in object files, but then again, where is the difference coming from? Can anyone elucidate on how I am seeing two different object files in my situation. If the include files are causing the difference, how come I see identical /E output? PS. The object files are different not only in the timestamp, but in the code sections also. In fact the behavior of my final executable is different in both cases. Edit: PSS: I even looked at the /includeFiles output of cl.exe and that output is identical. The object files, however, differ in more than just the timestamp (in fact, one is 1KB bigger than another!)

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  • Strange error when filling a data adapter.

    - by Tim C
    I am receiving the following error in my code (c#, .Net 3.5, VS2008) when I try to connect to an Excel sheet and fill a OleDbDataAdapter with the results of a query. First the error: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. And here is the code, which is honestly pretty simple: var excelFileName = string.Format("c:/Metadata_Tool.xlsm"); var connectionString = string.Format("Provider=Microsoft.ACE.OLEDB.12.0; Data Source={0}; Extended Properties=Excel 12.0;HDR=YES;", excelFileName); var adapter = new OleDbDataAdapter("Select * FROM [Video Tagging XML]", connectionString); var ds = new DataSet(); adapter.Fill(ds, "VTX"); DataTable data = ds.Tables["VTX"]; foreach (DataRow myRow in data.Rows) { foreach (DataColumn myColumn in data.Columns) { Console.Write("\t{0}", myRow[myColumn]); } Console.WriteLine(); } Console.ReadLine(); I get the error on the line adapter.Fill(ds,"VTX");. I did find a microsoft forum post saying to turn on JIT optimization in VS2008 from the Tools/Options/Debug/General menu, but this did not seem to help. Any help would be greatly appreciated thanks!

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  • Possible to Inspect Innards of Core C# Functionality

    - by Nick Babcock
    I was struck today, with the inclination to compare the innards of Buffer.BlockCopy and Array.CopyTo. I am curious to see if Array.CopyTo called Buffer.BlockCopy behind the scenes. There is no practical purpose behind this, I just want to further my understanding of the C# language and how it is implemented. Don't jump the gun and accuse me of micro-optimization, but you can accuse me of being curious! When I ran ILasm on mscorlib.dll I received this for Array.CopyTo .method public hidebysig newslot virtual final instance void CopyTo(class System.Array 'array', int32 index) cil managed { // Code size 0 (0x0) } // end of method Array::CopyTo and this for Buffer.BlockCopy .method public hidebysig static void BlockCopy(class System.Array src, int32 srcOffset, class System.Array dst, int32 dstOffset, int32 count) cil managed internalcall { .custom instance void System.Security.SecuritySafeCriticalAttribute::.ctor() = ( 01 00 00 00 ) } // end of method Buffer::BlockCopy Which, frankly, baffles me. I've never run ILasm on a dll/exe I didn't create. Does this mean that I won't be able to see how these functions are implemented? Searching around only revealed a stackoverflow question, which Marc Gravell said [Buffer.BlockCopy] is basically a wrapper over a raw mem-copy While insightful, it doesn't answer my question if Array.CopyTo calls Buffer.BlockCopy. I'm specifically interested in if I'm able to see how these two functions are implemented, and if I had future questions about the internals of C#, if it is possible for me to investigate it. Or am I out of luck?

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  • how to push different local git branches to heroku/master

    - by lsiden
    Heroku has a policy of ignoring all branches but 'master'. While I'm sure Heroku's designers have excellent reasons for for this policy (I'm guessing for storage and performance optimization), the consequence to me as a developer is that whatever local topic branch I may be working on, I would like an easy way to switch Heroku's master to that local topic branch and do a "git push heroku -f" to over-write master on Heroku. What I got from reading the "Pushing Refspecs" section of http://progit.org/book/ch9-5.html is git push -f heroku local-topic-branch:refs/heads/master What I'd really like is a way to set this up in the config file so that "git push heroku" always does the above, replacing local-topic-branch with the name of whatever my current branch happens to be. If anyone knows how to accomplish that, please let me know! The caveat for this, of course, is that this is only sensible if I am the only one who can push to that Heroku app/repository. A test or QA team might manage such a repository to try out different candidate branches, but they would have to coordinate so that they all agree on what branch they are pushing to it on any given day. Needless to say, it would also be a very good idea to have a separate remote repository (like Github) without this restriction for backing everything up to. I'd call that one "origin" and use "heroku" for Heroku so that "git push" always backs up everything to origin, and "git push heroku" pushes whatever branch I'm currently on to Heroku's master branch, overwriting it if necessary. Can anybody tell me if this would work? [remote "heroku"] url = [email protected]:my-app.git push = +refs/heads/*:refs/heads/master I'd like to hear from someone more experienced before I begin to experiment, although I suppose I could create a dummy app on Heroku and experiment with that. As for fetching, I don't really care if the Heroku repository is write-only. I still have a separate repository, like Github, for backup and cloning of all my work. Footnote: This question is similar to, but not quite the same as http://stackoverflow.com/questions/1489393/good-git-deployment-using-branches-strategy-with-heroku

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  • OpenGL depth buffer on Android

    - by kayahr
    I'm currently learning OpenGL ES programming on Android (2.1). I started with the obligatory rotating cube. It's rotating fine but I can't get the depth buffer to work. The polygons are always displayed in the order the GL commands render them. I do this during initialization of GL: gl.glClearColor(.5f, .5f, .5f, 1); gl.glShadeModel(GL10.GL_SMOOTH); gl.glClearDepthf(1f); gl.glEnable(GL10.GL_DEPTH_TEST); gl.glDepthFunc(GL10.GL_LEQUAL); gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST); On surface-change I do this: gl.glViewport(0, 0, width, height); gl.glMatrixMode(GL10.GL_PROJECTION); gl.glLoadIdentity(); GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f, 100f); When I enable backface culling then everything looks correct. But backface culling is only a speed-optimization so it should also work with only the depth buffer or not? So what is missing here?

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  • Dealing with Time Zones

    - by RavIncredible
    Hi All, I need some guidance with one of my project requirements, I am developing an application which has to deal with various time zones. Scenario: User 1 is from India, so his time zone would be GMT+05:30 User 2 is from UK, so his time zone would be GMT+01:00 If the User 1 sends a message to User 2, I want to show the Message Sent/Received Time as per the user’s time zone. For example User 1 sends a message at 6:30 Indian time, when User 2 would view the message it would show as 2:00 UK time. Here goes my question, whenever I save the message should I convert it to GMT+00, so all my base times stamps are the same and then later when I display the message, I convert it back to User specific time zone. Would this be complex? Is this the best way of doing this? I like to get views for both saving and displaying, also when I should do the time conversion from optimization point of view. I would need do deal with any/all timezones. I am developing this application with PHP and MySQL and I am aware of timezone conversion method come with both PHP and MySQL. I am just trying to figure out the best way of doing this. Look forward to have all valuable suggestions. Note : As of now I am not much worried with day/light savings. Thanks Ravi

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