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DNS NS and domain clarification

- by thejartender

I am really trying to get my home web server up and I don't seem to be succeeding. My web server withing my host system is running my web application and is viewable at the current isp ip 88.89.190.171 over WAN indicating that the webapp is fine and that router ports are forwarded. I have set up a DNS on this system with a single name server in the network and I manage to ping it with ping ns.thejarbar.org I have registered this private name server at my current hosting provider. My domain (thejarbar.org) is obviously registered and I have pointed it to my name server. My question here is if it is simply a matter of waiting on propagation for me to be able to ping my domain? Another way of asking this is if the fact that my name server is discoverable indicates that I have set it up correctly to be used? I have tested with dig and dig -x on my host and have A records for the name server. The server is not the Authorative server so I am concerned that this may be the reason why my site is not discoverable. Is there anything else I may need to so still? I only have one ns. currently, but should this succeed I will be purchasing a more stable secondary system to host my development applications. This is my best chance at getting work (freelance development) due to illness) and this I feel is the last step I need to succeed. Please note that this is temporarily a home server and I will most likely be using it as part of a professional setup very soon I will likely have to repeat this question therefore in a prefessional context in a few weeks as nothing will be different other than the fact that I am going to have a server running elsewhere. I am using bind9 and Ubuntu 12.10 and my records are: $TTL 3D @ IN SOA ns.thejarbar.org. email. ( 13112012 28800 3600 604800 38400 ); thejarbar.org. IN A 10.0.0.42 @ IN NS ns.thejarbar,org. yuccalaptop IN A 10.0.0.19 ns IN A 10.0.0.42 gw IN A 10.0.0.138 www IN CNAME thejarbar.org. $TTL 3D 0.0.10.in-addr.arpa. IN SOA ns.thejarbar.org. email. ( 13112012 28800 3600 604800 38400 ); 0.0.10.in-addr.arpa. IN NS ns.thejarbar.org. 42 IN PTR thejarbar.org. 19 IN PTR yuccalaptop.thejarbar.org. 138 IN PTR gw.thejarbar.org. My localhost IP is 10.0.0.42 I wish for this to be my host and name server.

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Detect duplicate in a subset from a set of elements

- by Abhinav Shrivastava

I have a set of numbers say : 1 1 2 8 5 6 6 7 8 8 4 2... I want to detect the duplicate element in subsets(of given size say k) of the above numbers... For example : Consider the increasing subsets(for example consider k=3) Subset 1 :{1,1,2} Subset 2 :{1,2,8} Subset 3 :{2,8,5} Subset 4 :{8,5,6} Subset 5 :{5,6,6} Subset 6 :{6,6,7} .... .... So my algorithm should detect that subset 1,5,6 contains duplicates.. My approach : 1)Copy the 1st k elements to a temporary array(vector) 2) using #include file in C++ STL...using unique() I would determine if there's any change in size of vector.. Any other clue how to approach this problem..

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Google search results are invalid

- by Rufus

I'm writing a program that lets a user perform a Google search. When the result comes back, all of the links in the search results are links not to other sites but to Google, and if the user clicks on one, the page is fetched not from the other site but from Google. Can anyone explain how to fix this problem? My Google URL consists of this: http://google.com/search?q=gargle But this is what I get back when the user clicks on the Wikipedia search result, which was http://www.google.com/url?q=http://en.wikipedia.org/wiki/Gargling&sa=U&ei=_4vkT5y555Wh6gGBeOzECg&ved=0CBMQejAe&usg=AFQjeNHd1eRV8Xef3LGeH6AvGxt-AF-Yjw <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html lang="en" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml"> <head> <title>Gargling - Wikipedia, the free encyclopedia</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <meta http-equiv="Content-Style-Type" content="text/css" /> <meta name="generator" content="MediaWiki 1.20wmf5" /> <meta http-equiv="last-modified" content="Fri, 09 Mar 2012 12:34:19 +0000" /> <meta name="last-modified-timestamp" content="1331296459" /> <meta name="last-modified-range" content="0" /> <link rel="alternate" type="application/x-wiki" title="Edit this page" > <link rel="edit" title="Edit this page" > <link rel="apple-touch-icon" > <link rel="shortcut icon" > <link rel="search" type="application/opensearchdescription+xml" > <link rel="EditURI" type="application/rsd+xml" > <link rel="copyright" > <link rel="alternate" type="application/atom+xml" title="Wikipedia Atom feed" > <link rel="stylesheet" href="//bits.wikimedia.org/en.wikipedia.org/load.php?debug=false&lang=en&modules=ext.gadget.teahouse%7Cext.wikihiero%7Cmediawiki.legacy.commonPrint%2Cshared%7Cskins.vector&only=styles&skin=vector&*" type="text/css" media="all" /> <style type="text/css" media="all">#mwe-lastmodified { display: none; }</style><meta name="ResourceLoaderDynamicStyles" content="" /> <link rel="stylesheet" href="//bits.wikimedia.org/en.wikipedia.org/load.php?debug=false&lang=en&modules=site&only=styles&skin=vector&*" type="text/css" media="all" /> <style type="text/css" media="all">a:lang(ar),a:lang(ckb),a:lang(fa),a:lang(kk-arab),a:lang(mzn),a:lang(ps),a:lang(ur){text-decoration:none} /* cache key: enwiki:resourceloader:filter:minify-css:7:d5a1bf6cbd05fc6cc2705e47f52062dc */</style>

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"IP May Be Forged" - Sendmail Warning

- by Mikey B

CentOS 5.x | SendMail 8 Can I get clarification on what exactly the warning "IP may be forged" means and what conditions cause it? I recently configured SendMail to relay email from my exchange server and it's showing that warning in the logs. The messages get delivered fine but I don't like the warnings. I originally thought that there was an inconsistency between the servername used in the EHLO statement from Exchange and the respective PTR record for the source IP for Exchange. But upon examining a packet capture, I see exchange using "EHLO domain.com" and that the source IP has a PTR of "domain.com". Maybe sendmail doesn't like that the greeting only has the domain? -M

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Best way to implement a simple bullet trajectory

- by AirieFenix

I searched and searched and although it's a fair simple question, I don't find the proper answer but general ideas (which I already have). I have a top-down game and I want to implement a gun which shoots bullets that follow a simple path (no physics nor change of trajectory, just go from A to B thing). a: vector of the position of the gun/player. b: vector of the mouse position (cross-hair). w: the vector of the bullet's trajectory. So, w=b-a. And the position of the bullet = [x=x0+speed*time*normalized w.x , y=y0+speed*time * normalized w.y]. I have the constructor: public Shot(int shipX, int shipY, int mouseX, int mouseY) { //I get mouse with Gdx.input.getX()/getY() ... this.shotTime = TimeUtils.millis(); this.posX = shipX; this.posY = shipY; //I used aVector = aVector.nor() here before but for some reason didn't work float tmp = (float) (Math.pow(mouseX-shipX, 2) + Math.pow(mouseY-shipY, 2)); tmp = (float) Math.sqrt(Math.abs(tmp)); this.vecX = (mouseX-shipX)/tmp; this.vecY = (mouseY-shipY)/tmp; } And here I update the position and draw the shot: public void drawShot(SpriteBatch batch) { this.lifeTime = TimeUtils.millis() - this.shotTime; //position = positionBefore + v*t this.posX = this.posX + this.vecX*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); this.posY = this.posY + this.vecY*this.lifeTime*speed*Gdx.graphics.getDeltaTime(); ... } Now, the behavior of the bullet seems very awkward, not going exactly where my mouse is (it's like the mouse is 30px off) and with a random speed. I know I probably need to open the old algebra book from college but I'd like somebody says if I'm in the right direction (or points me to it); if it's a calculation problem, a code problem or both. Also, is it possible that Gdx.input.getX() gives me non-precise position? Because when I draw the cross-hair it also draws off the cursor position. Sorry for the long post and sorry if it's a very basic question. Thanks!

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Point Light Soft Shadows

- by notabene

How to implement soft shadows for omni directional (point) light. We use typical shadow mapping technique. Depth is rendered to texture cube and addresing is pretty simple then. Just using vector from light to fragments world position. It works perfectly. Until you want soft shadows. In our engine we use PCSS technique for spot lights. But for point light there begins troubles. How to sample in 3D? I developed technique when orthonormal basis is created from a direction and upvector (0,1,0). And then multiply sampling vector (something like this (1.0,i/depthMapSize,j/depthMapSize) with this basis. But this (of course :)) looks pretty bad for vectors near (0,1,0) and (0,-1,0). I will appreciate any help on this.

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Understanding Unity3d physics: where is the force applied?

- by Heisenbug

I'm trying to understand which is the right way to apply forces to a RigidBody. I noticed that there are AddForce and AddRelativeForce methods, one applied in world space coordinate system meanwhile the other in the local space. The thing that I do not understand is the following: usually in physics library (es. Bullet) we can specify the force vector and also the force application point. How can I do this in Unity? Is it possible to apply a force vector in a specific point relative to the given RigidBody coordinate system? Where does AddForce apply the force?

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Ray Picking Problems

- by A Name I Haven't Decided On

I've read so many answers on here about how to do Ray Picking, that I thought I had the idea of it down. But when I try to implement it in my game, I get garbage. I'm working with LWJGL. Here's the code: public static Ray getPick(int mouseX, int mouseY){ glPushMatrix(); //Setting up the Mouse Clip Vector4f mouseClip = new Vector4f((float)mouseX * 2 / 960f - 1, 1 - (float)mouseY * 2 / 640f ,0 ,1); //Loading Matrices FloatBuffer modMatrix = BufferUtils.createFloatBuffer(16); FloatBuffer projMatrix = BufferUtils.createFloatBuffer(16); glGetFloat(GL_MODELVIEW_MATRIX, modMatrix); glGetFloat(GL_PROJECTION_MATRIX, projMatrix); //Assigning Matrices Matrix4f proj = new Matrix4f(); Matrix4f model = new Matrix4f(); model.load(modMatrix); proj.load(projMatrix); //Multiplying the Projection Matrix by the Model View Matrix Matrix4f tempView = new Matrix4f(); Matrix4f.mul(proj, model, tempView); tempView.invert(); //Getting the Camera Position in World Space. The 4th Column of the Model View Matrix. model.invert(); Point cameraPos = new Point(model.m30, model.m31, model.m32); //Theoretically getting the vector the Picking Ray goes Vector4f rayVector = new Vector4f(); Matrix4f.transform(tempView, mouseClip, rayVector); rayVector.translate((float)-cameraPos.getX(),(float) -cameraPos.getY(),(float) -cameraPos.getZ(), 0f); rayVector.normalise(); glPopMatrix(); //This Basically Spits out a value that changes as the Camera moves. //When the Mouse moves, the values change around 0.001 points from screen edge to edge. System.out.format("Vector: %f %f %f%n", rayVector.x, rayVector.y, rayVector.z); //return new Ray(cameraPos, rayVector); return null; } I don't really know why this isn't working. I was hoping some more experienced eyes might be able to help me out. I can get the camera position like a champ, it's the vector the rays going in that I can't seem to get right. Thanks.

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How to alter image pixels of a wild life bird?

- by NoobScratcher

Hello so I was hoping someone knew how to move or change color and position actual image pixels and could explain and show the code to do so. I know how to write pixels on a surface or screen-surface usigned int *ptr = static_cast <unsigned int *> (screen-pixels); int offset = y * (screen->pitch / sizeof(unsigned int)); ptr[offset + x] = color; But I don't know how to alter or manipulate a image pixel of a png image my thoughts on this was How do I get the values and locations of pixels and what do I have to write to make it happen? Then how do I actually change the values or locations of those gotten pixels and how do I make that happen? any ideas tip suggestions are also welcome! int main(int argc , char *argv[]) { SDL_Surface *Screen = SDL_SetVideoMode(640,480,32,SDL_SWSURFACE); SDL_Surface *Image; Image = IMG_Load("image.png"); bool done = false; SDL_Event event; while(!done) { SDL_FillRect(Screen,NULL,(0,0,0)); SDL_BlitSurface(Image,NULL,Screen,NULL); while(SDL_PollEvent(&event)) { switch(event.type) { case SDL_QUIT: return 0; break; } } SDL_Flip(Screen); } return 0; }

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Draw contour around object in Opengl

- by Maciekp

I need to draw contour around 2d objects in 3d space. I tried drawing lines around object(+points to fill the gap), but due to line width, some part of it(~50%) was covering object. I tried to use stencil buffer, to eliminate this problem, but I got sth like this(contour is green): http://goo.gl/OI5uc (sorry I can't post images, due to my reputation) You can see(where arrow points), that some parts of line are behind object, and some are above. This changes when I move camera, but always there is some part, that is covering it. Here is code, that I use for drawing object: glColorMask(1,1,1,1); std::list<CObjectOnScene*>::iterator objIter=ptr->objects.begin(),objEnd=ptr->objects.end(); int countStencilBit=1; while(objIter!=objEnd) { glColorMask(1,1,1,1); glStencilFunc(GL_ALWAYS,countStencilBit,countStencilBit); glStencilOp(GL_REPLACE,GL_KEEP,GL_REPLACE ); (*objIter)->DrawYourVertices(); glStencilFunc(GL_NOTEQUAL,countStencilBit,countStencilBit); glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE); (*objIter)->DrawYourBorder(); ++objIter; ++countStencilBit; } I've tried different settings of stencil buffer, but always I was getting sth like that. Here is question: 1.Am I setting stencil buffer wrong? 2. Are there any other simple ways to create contour on such objects? Thanks in advance.

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Translate along local axis

- by Aaron

I have an object with a position matrix and a rotation matrix (derived from a quaternion, but I digress). I'm able to translate this object along world-relative vectors, but I'm trying to figure out how to translate it along local-relative vectors. So if the object is tilted 45 degrees around its Z-axis the vector (1, 0, 0) would make it move to the upper right. For world-space translations I simply turn the movement vector into a matrix and multiply it by the position matrix: position_mat = translation_mat * position_mat. For local-space translations I'd think I'd have to use the rotation matrix into that formula, but I see the object spin around instead when I apply a translation over time no matter where I multiply the rotation matrix.

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Draw contour around object in Opengl

- by Maciekp

I need to draw contour around 2d objects in 3d space. I tried drawing lines around object(+points to fill the gap), but due to line width, some part of it(~50%) was covering object. I tried to use stencil buffer, to eliminate this problem, but I got sth like this(contour is green): http://goo.gl/OI5uc (sorry I can't post images, due to my reputation) You can see(where arrow points), that some parts of line are behind object, and some are above. This changes when I move camera, but always there is some part, that is covering it. Here is code, that I use for drawing object: glColorMask(1,1,1,1); std::list<CObjectOnScene*>::iterator objIter=ptr->objects.begin(),objEnd=ptr->objects.end(); int countStencilBit=1; while(objIter!=objEnd) { glColorMask(1,1,1,1); glStencilFunc(GL_ALWAYS,countStencilBit,countStencilBit); glStencilOp(GL_REPLACE,GL_KEEP,GL_REPLACE ); (*objIter)->DrawYourVertices(); glStencilFunc(GL_NOTEQUAL,countStencilBit,countStencilBit); glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE); (*objIter)->DrawYourBorder(); ++objIter; ++countStencilBit; } I've tried different settings of stencil buffer, but always I was getting sth like that. Here is question: 1.Am I setting stencil buffer wrong? 2. Are there any other simple ways to create contour on such objects? Thanks in advance. EDIT: 1. I don't have normals of objects. 2. Object can be concave. 3. I can't use shaders(see below why).

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How do I best remove an entity from my game loop when it is dead?

- by Iain

Ok so I have a big list of all my entities which I loop through and update. In AS3 I can store this as an Array (dynamic length, untyped), a Vector (typed) or a linked list (not native). At the moment I'm using Array but I plan to change to Vector or linked list if it is faster. Anyway, my question, when an Entity is destroyed, how should I remove it from the list? I could null its position, splice it out or just set a flag on it to say "skip over me, I'm dead." I'm pooling my entities, so an Entity that is dead is quite likely to be alive again at some point. For each type of collection what is my best strategy, and which combination of collection type and removal method will work best?

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ssh, "Last Login", `last` and OS X

- by allentown

I have hit the googles as much as I can on this, being specific to OS X, I am not finding an answer. Nothing is wrong, but curiosity levels are high. $ssh [email protected] Password: Last login: Wed Apr 7 21:28:03 2010 from my-laptop.local ^lonely tylenol^ Line 1 is my command line 2 is the shell asking for the password line 3 is where my question comes from line 4 comes out of /etc/motd I can find nothing in ~/ of an of the .bash* files that contains the string "Last Login", and would like to alter it. It performs some type of hostname lookup, which I can not determine. If I ssh to another host: $ssh [email protected] Last login: Wed Apr 7 21:14:51 2010 from 123-234-321-123-some.cal.isp.net.example hi there, you are on box 456 line 1 is my command line 2 is again, where my question comes from line 3 is from /etc/motd *The dash'd IP address is not reversed On this remote host, I have ~/.ssh and it's corresponding keys set up, so there was no password request Where is the "Last Login:" coming from, where does the date stamp come from, and most importantly, where does the hostname come from? While on [email protected] (box 456) $echo hostname remote.location.example456.com Or with dig, to make sure I have rDNS/PTR set up, for which I am not authoritative, but my ISP has correctly set... $dig -x 123.234.321.123 PTR remote.location.example456.com or $dig PTR 123.321.234.123.in-addr.arpa. +short remote.location.example456.com. my previous hostname used to be 123-234-321-123-some.cal.isp.net.example, which I set with hostname -s remote.location.example456.com, because it was obnoxious to see such a long name. That solves the value of $echo hostname which now returns remote.location.example456.com. Mac OS X, 10.6 is this case, does seem to honor: touch ~/.hushlogin If leave that file empty, I get nothing on the shell when I login. I want to know what controls the host resolution of the IP, and how it is all working. For example, running last reports a huge list of my logins, which have obtusely long hostnames, when they would be preferable to just be remote.location.example456.com. More confusing to me, reading the man page for wtmp and lastlog, it looks like lastlog is not used on OS X, /var/log/lastlog does not exist. Actually, none of these exist on 10.5 or 10.6: /var/run/utmp The utmp file. /var/log/wtmp The wtmp file. /var/log/lastlog The lastlog file. If I am to assume that the system is doing some kind of reverse lookup, I certainly do not know what it is, as it is not an accurate one.

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Resolving equivalence relations

- by Luca Cerone

I am writing a function to label the connected component in an image (I know there are several libraries outside, I just wanted to play with the algorithm). To do this I label the connected regions with different labels and create an equivalence table that contain information on the labels belonging to the same connected component. As an example if my equivalence table (vector of vector) looks something like: 1: 1,3 2: 2,3 3: 1,2,3 4: 4 It means that in the image there are 2 different regions, one made of elements that are labelled 1,2,3 and an other made of elements labelled 4. What is an easy and efficient way to resolve the equivalences and end up with something that looks like: 1: 1,2,3 2: 4 that I can use to "merge" the different connected regions belonging to the same connected component? Thanks a lot for the help!

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Size of an image imported with FreeImage

- by KaiserJohaan

I'm having abit of a brainfart and I can't quite grasp what I'm doing wrong. It's quite simple, I am importing an image with FreeImage (http://freeimage.sourceforge.net/) which has a method FreeImage_GetBits that returns a pointer to the first byte of the image data. I then try to load all the data into memory using (bitsperpixel / 8) * pixelsWidth ' pixelHeight, like this: uint32_t bitsPerPixel = FreeImage_GetBPP(bitmap); // resolves to 24 uint32_t widthInPixels = FreeImage_GetWidth(bitmap); // resolves to 1024 uint32_t heightInPixels = FreeImage_GetHeight(bitmap); // resolves to 1024 // container is a std::vector<uint8_t> pkgMaterial.mTextureData.insert(pkgMaterial.mTextureData.begin(), FreeImage_GetBits(bitmap), FreeImage_GetBits(bitmap) + ((bitsPerPixel/8) * widthInPixels * heightInPixels)); I have a jpg which is 31 kilobytes in size on disc. Yet when I load it using the above formula, I see the vector is then filled with 3145728 bytes, which is approx 3145 kilobytes. What am I doing wrong?

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Placing items randomly in a dynamically generated terrain

- by Programlocura

I'm currently working on a 'Tiny wings' like game. I've already asked about the angle of the items in curved lines and i solved (thank you for responses),i'm currently placing the items in random positions, but the terrain it's dynamically and i don't get this working. I've a vector with the points of the terrain, and i'm doing something similar to this (Iterating trough vector): if( _SPManager && i % 15 == 0 && i != 0 ) { if ( _settings.specialPoints && _currentPoints < _settings.specialPoints ) { _SPManager.addPoint( _hillsPosition[i].x , _hillsPosition[i].y ); _currentPoints++; } } But it isn't working as i expected. It isn't displaying the right number of items (Always shows less than i specified). How do i should place the items? Thanks :)

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VFP Unit Matrix Multiply problem on the iPhone

- by Ian Copland

Hi. I'm trying to write a Matrix3x3 multiply using the Vector Floating Point on the iPhone, however i'm encountering some problems. This is my first attempt at writing any ARM assembly, so it could be a faily simple solution that i'm not seeing. I've currently got a small application running using a maths library that i've written. I'm investigating into the benifits using the Vector Floating Point Unit would provide so i've taken my matrix multiply and converted it to asm. Previously the application would run without a problem, however now my objects will all randomly disappear. This seems to be caused by the results from my matrix multiply becoming NAN at some point. Heres the code IMatrix3x3 operator*(IMatrix3x3 & _A, IMatrix3x3 & _B) { IMatrix3x3 C; //C++ code for the simulator #if TARGET_IPHONE_SIMULATOR == true C.A0 = _A.A0 * _B.A0 + _A.A1 * _B.B0 + _A.A2 * _B.C0; C.A1 = _A.A0 * _B.A1 + _A.A1 * _B.B1 + _A.A2 * _B.C1; C.A2 = _A.A0 * _B.A2 + _A.A1 * _B.B2 + _A.A2 * _B.C2; C.B0 = _A.B0 * _B.A0 + _A.B1 * _B.B0 + _A.B2 * _B.C0; C.B1 = _A.B0 * _B.A1 + _A.B1 * _B.B1 + _A.B2 * _B.C1; C.B2 = _A.B0 * _B.A2 + _A.B1 * _B.B2 + _A.B2 * _B.C2; C.C0 = _A.C0 * _B.A0 + _A.C1 * _B.B0 + _A.C2 * _B.C0; C.C1 = _A.C0 * _B.A1 + _A.C1 * _B.B1 + _A.C2 * _B.C1; C.C2 = _A.C0 * _B.A2 + _A.C1 * _B.B2 + _A.C2 * _B.C2; //VPU ARM asm for the device #else //create a pointer to the Matrices IMatrix3x3 * pA = &_A; IMatrix3x3 * pB = &_B; IMatrix3x3 * pC = &C; //asm code asm volatile( //turn on a vector depth of 3 "fmrx r0, fpscr \n\t" "bic r0, r0, #0x00370000 \n\t" "orr r0, r0, #0x00020000 \n\t" "fmxr fpscr, r0 \n\t" //load matrix B into the vector bank "fldmias %1, {s8-s16} \n\t" //load the first row of A into the scalar bank "fldmias %0!, {s0-s2} \n\t" //calulate C.A0, C.A1 and C.A2 "fmuls s17, s8, s0 \n\t" "fmacs s17, s11, s1 \n\t" "fmacs s17, s14, s2 \n\t" //save this into the output "fstmias %2!, {s17-s19} \n\t" //load the second row of A into the scalar bank "fldmias %0!, {s0-s2} \n\t" //calulate C.B0, C.B1 and C.B2 "fmuls s17, s8, s0 \n\t" "fmacs s17, s11, s1 \n\t" "fmacs s17, s14, s2 \n\t" //save this into the output "fstmias %2!, {s17-s19} \n\t" //load the third row of A into the scalar bank "fldmias %0!, {s0-s2} \n\t" //calulate C.C0, C.C1 and C.C2 "fmuls s17, s8, s0 \n\t" "fmacs s17, s11, s1 \n\t" "fmacs s17, s14, s2 \n\t" //save this into the output "fstmias %2!, {s17-s19} \n\t" //set the vector depth back to 1 "fmrx r0, fpscr \n\t" "bic r0, r0, #0x00370000 \n\t" "orr r0, r0, #0x00000000 \n\t" "fmxr fpscr, r0 \n\t" //pass the inputs and set the clobber list : "+r"(pA), "+r"(pB), "+r" (pC) : :"cc", "memory","s0", "s1", "s2", "s8", "s9", "s10", "s11", "s12", "s13", "s14", "s15", "s16", "s17", "s18", "s19" ); #endif return C; } As far as i can see that makes sence. While debugging i've managed to notice that if i were to say _A = C prior to the return and after the ASM, _A will not necessarily be equal to C which has only increased my confusion. I had thought it was possibly due to the pointers I'm giving to the VFPU being incrimented by lines such as "fldmias %0!, {s0-s2} \n\t" however my understanding of asm is not good enough to properly understand the problem, nor to see an alternative approach to that line of code. Anyway, I was hoping someone with a greater understanding than me would be able to see a solution, and any help would be greatly appreciated, thank you :-)

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Problem with memset after an instance of a user defined class is created and a file is opened

- by Liberalkid

I'm having a weird problem with memset, that was something to do with a class I'm creating before it and a file I'm opening in the constructor. The class I'm working with normally reads in an array and transforms it into another array, but that's not important. The class I'm working with is: #include <vector> #include <algorithm> using namespace std; class PreProcess { public: PreProcess(char* fileName,char* outFileName); void SortedOrder(); private: vector< vector<double > > matrix; void SortRow(vector<double> &row); char* newFileName; vector< pair<double,int> > rowSorted; }; The other functions aren't important, because I've stopped calling them and the problem persists. Essentially I've narrowed it down to my constructor: PreProcess::PreProcess(char* fileName,char* outFileName):newFileName(outFileName){ ifstream input(fileName); input.close(); //this statement is inconsequential } I also read in the file in my constructor, but I've found that the problem persists if I don't read in the matrix and just open the file. Essentially I've narrowed it down to if I comment out those two lines the memset works properly, otherwise it doesn't. Now to the context of the problem I'm having with it: I wrote my own simple wrapper class for matrices. It doesn't have much functionality, I just need 2D arrays in the next part of my project and having a class handle everything makes more sense to me. The header file: #include <iostream> using namespace std; class Matrix{ public: Matrix(int r,int c); int &operator()(int i,int j) {//I know I should check my bounds here return matrix[i*columns+j]; } ~Matrix(); const void Display(); private: int *matrix; const int rows; const int columns; }; Driver: #include "Matrix.h" #include <string> using namespace std; Matrix::Matrix(int r,int c):rows(r),columns(c) { matrix=new int[rows*columns]; memset(matrix,0,sizeof(matrix)); } const void Matrix::Display(){ for(int i=0;i<rows;i++){ for(int j=0;j<columns;j++) cout << (*this)(i,j) << " "; cout << endl; } } Matrix::~Matrix() { delete matrix; } My main program runs: PreProcess test1(argv[1],argv[2]); //test1.SortedOrder(); Matrix test(10,10); test.Display(); And when I run this with the input line uncommented I get: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371727776 32698 -1 0 0 0 0 0 6332656 0 -1 -1 0 0 6332672 0 0 0 0 0 0 0 0 0 0 0 0 0 -1371732704 32698 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 I really don't have a clue what's going on in memory to cause this, on a side note if I replace memset with: for(int i=0;i<rows*columns;i++) *(matrix+i) &= 0x0; Then it works perfectly, it also works if I don't open the file. If it helps I'm running GCC 64-bit version 4.2.4 on Ubuntu.I assume there's some functionality of memset that I'm not properly understanding.

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What container type provides better (average) performance than std::map?

- by Truncheon

In the following example a std::map structure is filled with 26 values from A - Z (for key) and 0 - 26 for value. The time taken (on my system) to lookup the last entry (10000000 times) is roughly 250 ms for the vector, and 125 ms for the map. (I compiled using release mode, with O3 option turned on for g++ 4.4) But if for some odd reason I wanted better performance than the std::map, what data structures and functions would I need to consider using? I apologize if the answer seems obvious to you, but I haven't had much experience in the performance critical aspects of C++ programming. UPDATE: This example is rather trivial and hides the true complexity of what I'm trying to achieve. My real world project is a simple scripting language that uses a parser, data tree, and interpreter (instead of a VM stack system). I need to use some kind of data structure (perhaps map) to store the variables names created by script programmers. These are likely to be pretty randomly named, so I need a lookup method that can quickly find a particular key within a (probably) fairly large list of names. #include <ctime> #include <map> #include <vector> #include <iostream> struct mystruct { char key; int value; mystruct(char k = 0, int v = 0) : key(k), value(v) { } }; int find(const std::vector<mystruct>& ref, char key) { for (std::vector<mystruct>::const_iterator i = ref.begin(); i != ref.end(); ++i) if (i->key == key) return i->value; return -1; } int main() { std::map<char, int> mymap; std::vector<mystruct> myvec; for (int i = 'a'; i < 'a' + 26; ++i) { mymap[i] = i - 'a'; myvec.push_back(mystruct(i, i - 'a')); } int pre = clock(); for (int i = 0; i < 10000000; ++i) { find(myvec, 'z'); } std::cout << "linear scan: milli " << clock() - pre << "\n"; pre = clock(); for (int i = 0; i < 10000000; ++i) { mymap['z']; } std::cout << "map scan: milli " << clock() - pre << "\n"; return 0; }

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Boost::Spirit::Qi autorules -- avoiding repeated copying of AST data structures

- by phooji

I've been using Qi and Karma to do some processing on several small languages. Most of the grammars are pretty small (20-40 rules). I've been able to use autorules almost exclusively, so my parse trees consist entirely of variants, structs, and std::vectors. This setup works great for the common case: 1) parse something (Qi), 2) make minor manipulations to the parse tree (visitor), and 3) output something (Karma). However, I'm concerned about what will happen if I want to make complex structural changes to a syntax tree, like moving big subtrees around. Consider the following toy example: A grammar for s-expr-style logical expressions that uses autorules... // Inside grammar class; rule names match struct names... pexpr %= pand | por | var | bconst; pand %= lit("(and ") >> (pexpr % lit(" ")) >> ")"; por %= lit("(or ") >> (pexpr % lit(" ")) >> ")"; pnot %= lit("(not ") >> pexpr >> ")"; ... which leads to parse tree representation that looks like this... struct var { std::string name; }; struct bconst { bool val; }; struct pand; struct por; struct pnot; typedef boost::variant<bconst, var, boost::recursive_wrapper<pand>, boost::recursive_wrapper<por>, boost::recursive_wrapper<pnot> > pexpr; struct pand { std::vector<pexpr> operands; }; struct por { std::vector<pexpr> operands; }; struct pnot { pexpr victim; }; // Many Fusion Macros here Suppose I have a parse tree that looks something like this: pand / ... \ por por / \ / \ var var var var (The ellipsis means 'many more children of similar shape for pand.') Now, suppose that I want negate each of the por nodes, so that the end result is: pand / ... \ pnot pnot | | por por / \ / \ var var var var The direct approach would be, for each por subtree: - create pnot node (copies por in construction); - re-assign the appropriate vector slot in the pand node (copies pnot node and its por subtree). Alternatively, I could construct a separate vector, and then replace (swap) the pand vector wholesale, eliminating a second round of copying. All of this seems cumbersome compared to a pointer-based tree representation, which would allow for the pnot nodes to be inserted without any copying of existing nodes. My question: Is there a way to avoid copy-heavy tree manipulations with autorule-compliant data structures? Should I bite the bullet and just use non-autorules to build a pointer-based AST (e.g., http://boost-spirit.com/home/2010/03/11/s-expressions-and-variants/)?

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Intrinsics program (SSE) - g++ - help needed

- by Sriram

Hi all, This is the first time I am posting a question on stackoverflow, so please try and overlook any errors I may have made in formatting my question/code. But please do point the same out to me so I may be more careful. I was trying to write some simple intrinsics routines for the addition of two 128-bit (containing 4 float variables) numbers. I found some code on the net and was trying to get it to run on my system. The code is as follows: //this is a sample Intrinsics program to add two vectors. #include <iostream> #include <iomanip> #include <xmmintrin.h> #include <stdio.h> using namespace std; struct vector4 { float x, y, z, w; }; //functions to operate on them. vector4 set_vector(float x, float y, float z, float w = 0) { vector4 temp; temp.x = x; temp.y = y; temp.z = z; temp.w = w; return temp; } void print_vector(const vector4& v) { cout << " This is the contents of vector: " << endl; cout << " > vector.x = " << v.x << endl; cout << " vector.y = " << v.y << endl; cout << " vector.z = " << v.z << endl; cout << " vector.w = " << v.w << endl; } vector4 sse_vector4_add(const vector4&a, const vector4& b) { vector4 result; asm volatile ( "movl $a, %eax" //move operands into registers. "\n\tmovl $b, %ebx" "\n\tmovups (%eax), xmm0" //move register contents into SSE registers. "\n\tmovups (%ebx), xmm1" "\n\taddps xmm0, xmm1" //add the elements. addps operates on single-precision vectors. "\n\t movups xmm0, result" //move result into vector4 type data. ); return result; } int main() { vector4 a, b, result; a = set_vector(1.1, 2.1, 3.2, 4.5); b = set_vector(2.2, 4.2, 5.6); result = sse_vector4_add(a, b); print_vector(a); print_vector(b); print_vector(result); return 0; } The g++ parameters I use are: g++ -Wall -pedantic -g -march=i386 -msse intrinsics_SSE_example.C -o h The errors I get are as follows: intrinsics_SSE_example.C: Assembler messages: intrinsics_SSE_example.C:45: Error: too many memory references for movups intrinsics_SSE_example.C:46: Error: too many memory references for movups intrinsics_SSE_example.C:47: Error: too many memory references for addps intrinsics_SSE_example.C:48: Error: too many memory references for movups I have spent a lot of time on trying to debug these errors, googled them and so on. I am a complete noob to Intrinsics and so may have overlooked some important things. Any help is appreciated, Thanks, Sriram.

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What's the fastest lookup algorithm for a pair data structure (i.e, a map)?

- by truncheon

In the following example a std::map structure is filled with 26 values from A - Z (for key) and 0 – 26 for value. The time taken (on my system) to lookup the last entry (10000000 times) is roughly 250 ms for the vector, and 125 ms for the map. (I compiled using release mode, with O3 option turned on for g++ 4.4) But if for some odd reason I wanted better performance than the std::map, what data structures and functions would I need to consider using? I apologize if the answer seems obvious to you, but I haven't had much experience in the performance critical aspects of C++ programming. UPDATE: This example is rather trivial and hides the true complexity of what I'm trying to achieve. My real world project is a simple scripting language that uses a parser, data tree, and interpreter (instead of a VM stack system). I need to use some kind of data structure (perhaps map) to store the variables names created by script programmers. These are likely to be pretty randomly named, so I need a lookup method that can quickly find a particular key within a (probably) fairly large list of names. #include <ctime> #include <map> #include <vector> #include <iostream> struct mystruct { char key; int value; mystruct(char k = 0, int v = 0) : key(k), value(v) { } }; int find(const std::vector<mystruct>& ref, char key) { for (std::vector<mystruct>::const_iterator i = ref.begin(); i != ref.end(); ++i) if (i->key == key) return i->value; return -1; } int main() { std::map<char, int> mymap; std::vector<mystruct> myvec; for (int i = 'a'; i < 'a' + 26; ++i) { mymap[i] = i - 'a'; myvec.push_back(mystruct(i, i - 'a')); } int pre = clock(); for (int i = 0; i < 10000000; ++i) { find(myvec, 'z'); } std::cout << "linear scan: milli " << clock() - pre << "\n"; pre = clock(); for (int i = 0; i < 10000000; ++i) { mymap['z']; } std::cout << "map scan: milli " << clock() - pre << "\n"; return 0; }

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Terminal Server 2008: Remote App Issue

- by JohnyD

I have a FoxPro 2.6 (16-bit) application that I've installed on a Win2008 (32-bit) Terminal Server. I then created a Remote App from it. It works fine. The problem is that within this FoxPro application it calls out to a .Net application. I have the proper .Net Framework installed on the server (2.0) and I have run the code access security policy tool (caspol.exe). However, when I launch the .Net app from within the FoxPro application I get the following error: Description: Stopped working Problem signature: Problem Event Name: CLR20r3 Problem Signature 01: vector.exe Problem Signature 02: 1.0.0.3 Problem Signature 03: 48b579f2 Problem Signature 04: vector Problem Signature 05: 1.0.0.3 Problem Signature 06: 48b579f2 Problem Signature 07: f Problem Signature 08: 57 Problem Signature 09: System.Security.Security OS Version: 6.0.6001.2.1.0.18.10 Locale ID: 1033 Vector.exe is our .Net application. In fact, it's an in-between application that checks to ensure you have the latest version. When it's done it calls out to another .Net executable. Does anyone believe this should be a problem? Thanks in advance.

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Java constructor using generic types

- by user37903

I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method initBreweryFromObject() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // initBreweryFromObject() is an instance method // of Brewery, of which <T> is a subclass (right?) c.initBreweryFromObject(); // "The method initBreweryFromObject() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void androidMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

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