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  • Transparent BITMAP WinAPI

    - by user146780
    I want to implement a layering system in my application and was thinking of creating a bunch of trabsparent bitmaps, adding content to them then blitting them on top of each other, how can this be done without setting each pixel to (0,0,0,0). I'm using Pure win32, not MFC, thanks.

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  • BlackBerry - Cropping image

    - by rupesh
    Hi all i want to crop a part of Image ,for that i am using following code: int x=20; int y=50; int [] rgbdata=new int[(0+width-x+height-y)* (image.getWidth())]; image.getARGB(rgbdata, 0, image.getWidth(), x, y, width, height); cropedImage=new Bitmap(image.getWidth(),image.getWidth()); cropedImage.setARGB(rgbdata, 0,image.getWidth(), 80,80, width, height); x an y are the position from where the cropping will be done in the rectangular form. but it is not working can any one help me out please. any sample code will work for me. its urgent. thanks in advance

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  • xaml shapes - relative to canvas size

    - by taglius
    I have the need to draw shapes in XAML that are always relative to the container window/canvas size. For example, I need a window to show a 3x3 grid on it, where the grid always splits the window into 3 equal parts. Can I create lines that are bound to 1/3 the width of the grid? thank you

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  • How to detect iPhone movement in space using accelerometer ?

    - by super_tomtom
    Hi ! I am trying to make an application that would detect what kind of shape you made with your iPhone using accelerometer. As an example, if you draw a circle with your hand holding the iPhone, the app would be able to redraw it on the screen. This could also work with squares, or even more complicated shapes. The only example of application I've seen doing such a thing is AirPaint (http://vimeo.com/2276713), but it doesn't seems to be able to do it in real time. My first try is to apply a low-pass filter on the X and Y parameters from the accelerometer, and to make a pointer move toward these values, proportionally to the size of the screen. But this is clearly not enought, I have a very low accuracy, and if I shake the device it also makes the pointer move... Any ideas about that ? Do you think accelerometer data is enought to do it ? Or should I consider using other data, such as the compass ? Thanks in advance !

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  • Clip a 4:3 image in WPF with a circle

    - by reckoner
    I am trying to clip a 4:3 image with a circle within a grid control. I need the circle clip to reveal the image from the middle in a perfect circle. See below. The circle should dynamically re-size with the image. I have tried Canvas.Clip and Ellipse+VisualBrush without achieving the correct behavior. Thanks!

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  • cocos2d - how to draw a bottle sprite with dynamically changing water level

    - by Oliver
    I am trying to draw a (2d) sprite in cocos2d showing a bottle. The bottle shall be able to have a dynamic water level (i.e. the amount of water in the bottle can change over the lifetime of the sprite). I am wondering how to do this. I currently have a PNG file of the empty bottle. I adjusted the alpha channel of that PNG so when rendering the sprite I can draw a blue rectangle and render the bottle texture over it. That will give the impression of the water being inside the bottle. However, the bottle's shape is not a rectangle itself of course, so the water can be seen out of the bounds of the bottle. I can change the bottle image in a way that only the bottle itself is transparent and set the "outside world" to an opaque color & alpha channel value, but that again prevents the "world background" to be visible in that area. I simply don't have a clue how to realize this in a sane manner. Do I really have to read every pixel of the bottle image, identify which pixel is "inside" of the bottle and then draw the water pixel by pixel? There must be an easier way, right? ;) Any best practices for these kinds of tasks? edit: see picture below, to make somewhat clearer, what I am talking about ;) http://i47.tinypic.com/10rqww0.png

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  • Resizing gives me to heavy image

    - by phenevo
    Hi, I'm resizing jpeg 1200x900 ,556kb by method: public static Image ResizeImage(Image imgToResize, int height) //height=400 { int destWidth; int destHeight; int sourceWidth = imgToResize.Width; int sourceHeight = imgToResize.Height; float nPercent = 0; float nPercentH = 0; nPercentH = ((float)height / (float)sourceHeight); nPercent = nPercentH; destWidth = (int)(sourceWidth * nPercent); destHeight = height; Bitmap b = new Bitmap(destWidth, destHeight); Graphics g = Graphics.FromImage((Image)b); g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(imgToResize, 0, 0, destWidth, destHeight); g.Dispose(); return b; } gives me 555kb 533x400 jpeg. Why this photo is so heavy. For photo jpeg 2111kb 2156x1571 I get 556kb 533x400 jpeg Why in first case is so terrible !

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  • when is the right time to draw

    - by stupid_idiot
    hi i just finished essential part of my own personal 2d engine in c++ and i'm kinda deciding how to complete the part where it is actually supposed to display everything on the screen, namely when do I call that function which does the job. I don't have much idea of how does the graphic card work, my biggest experience is calling bios graphic services to write some stuff on the screen. Could you give me a hint on this pls? Or maybe some keywords I should try to google?

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  • Determining the color of a pixel in a bitmap using C# in a WPF app

    - by DanM
    The only way I found so far is System.Drawing.Bitmap.GetPixel(), but Microsoft has warnings for System.Drawing that are making me wonder if this is the "old way" to do it. Are there any alternatives? Here's what Microsoft says about the System.Drawing namespace. I also noticed that the System.Drawing assembly was not automatically added to the references when I created a new WPF project. System.Drawing Namespace The System.Drawing namespace provides access to GDI+ basic graphics functionality. More advanced functionality is provided in the System.Drawing.Drawing2D, System.Drawing.Imaging, and System.Drawing.Text namespaces. The Graphics class provides methods for drawing to the display device. Classes such as Rectangle and Point encapsulate GDI+ primitives. The Pen class is used to draw lines and curves, while classes derived from the abstract class Brush are used to fill the interiors of shapes. Caution Classes within the System.Drawing namespace are not supported for use within a Windows or ASP.NET service. Attempting to use these classes from within one of these application types may produce unexpected problems, such as diminished service performance and run-time exceptions. - http://msdn.microsoft.com/en-us/library/system.drawing.aspx

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  • Why did Intel drop the Itanium?

    - by Cole Johnson
    I was reading up on the history of the computer and I came along the IA-64 (Itanium) processors. They sounded really interesting and I was confused as to why Intel would decide to drop them. The ability to choose explicitly what 2 instructions you wanted to run in that cycle is a great idea, especially when writing your program in assembly, for example, a faster bootloader. The hundreds of registers should be convincing for any assembly programmer. You could essentially store all the functions variables in the registers if it doesn't call any other ones. The ability to do instructions like this: (qp) xor r1 = r2, r3 ; r1 = r2 XOR r3 (qp) xor r1 = (imm8), r3 ; r1 = (imm8) XOR r3 versus having to do: ; eax = r1 ; ebx = r2 ; ecx = r3 mov eax, ebx ; first put r2 into r1 xor eax, ecx ; then set r1 equivalent to r2 XOR r3 or ; SAME mov eax, (imm32) ; first put (imm32) into r1 xor eax, ecx ; then set r1 equivalent to (imm32) XOR r3 I heard it was because of no backwards x86 comparability, but couldn't thy be fixed by just adding the Pentium circuitry to it and just add a processor flag that would switch it to Itanium mode (like switching to Protected or Long mode) All the great things about it would have surly put them a giant leap ahead of AMD. Any ideas? Sadly this means you will need a very advanced compiler to do this. Or even one per specific model of the CPU. (E.g. a newer version of the Itanium with an extra feature would require different compiler). When I was working on a WinForms (target only had .NET 2.0) project in Visual Studio 2010, I had a compile target of IA-64. That means that there is a .NET runtime that was able to be compiled for IA-64 and a .NET runtime means Windows. Plus, Hamilton's answer mentions Windows NT. Having a full blown OS like Windows NT means that there is a compiler capable of generating IA-64 machine code.

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  • This code changes the textbox instantly to red. I want it like, click button then red, again then green

    - by user1803685
    This code changes the textbox instantly to red. I want it like, click button then red, again then green. private void button1_Click(object sender, EventArgs e) { textBox1.BackColor = System.Drawing.Color.Black; if (textBox1.BackColor.Equals(System.Drawing.Color.Black)) { textBox1.BackColor = System.Drawing.Color.Red; } if (textBox1.BackColor.Equals(System.Drawing.Color.Red)) { textBox1.BackColor = System.Drawing.Color.Green; } if (textBox1.BackColor.Equals(System.Drawing.Color.Green)) { textBox1.BackColor = System.Drawing.Color.Blue; } if (textBox1.BackColor.Equals(System.Drawing.Color.Blue)) { textBox1.BackColor = System.Drawing.Color.Red; } }

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  • Sequence for authentication on a decoupled client?

    - by A T
    Using a sequence diagram and example code could you explain to me how authentication works when the client is completely separated from the server? I.e.: you haven't generated any of the client using a server-side template engine, rather you are communicating using REST (SOAP xor HTTP) xor RPC (XML xor JSON) with javascript on the client-side. Specifically I would like to know the sequence of: Authenticating using basic auth (user+pass) with "my" server Authenticating using OAuth2, e.g.: with Facebook, with facebook's server then whatever extra steps are needed for "my" server And how it could be implemented. (feel free to use psuedo-code [like below] or [preferably] prototyped simply using BackboneJS, AngularJS, EmberJS, BatmanJS, AgilityJS, SammyJS xor ActiveJS. if cookie.status in [Expired, Tampered, Wrong IP, Invalid, Not Found]: try auth(user,pass): if user is in my db: try authenticate(user,pass) if successful: login user # give session-cookie here? else: present user with "auth failed" msg else if user not in db: redirect to "edit-profile" page PS: I have written an example (editable) auth sequence diagram; based on facebooks' documentation.

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  • Drawing of a huge model - How to regain performance?

    - by marc wellman
    I have a huge model I want to draw in my XNA application but because of its size I am experiencing a tremendous loss of performance. The model has about ~50 000 000 edges and has a size on disk of 205 MB in DirectX Format. Please don't ask whether this model has to be that big - yes it has! Is there a way to transfer the model directly to my GPU in order to let the GPU do the drawing like when transferring a VertexBuffer like this: graphicsDevice.Vertices[1].SetSource(_instanceBuffers[i], 0, _sizeofMatrix); because when I try to fill a vertexBuffer with all the vertices I am getting a OutOfMemoryException.

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  • Data structures for storing finger/stylus movements in drawing application?

    - by mattja?øb
    I have a general question about creating a drawing application, the language could be C++ or ObjectiveC with OpenGL. I would like to hear what are the best methods and practices for storing strokes data. Think of the many iPad apps that allow you to draw with your finger (or a stylus) or any other similar function on a desktop app. To summarize, the data structure must: be highly responsive to the movement store precise values (close in space / time) usable for rendering the strokes with complex textures (textures based on the dynamic of the stroke etc) exportable to a text file for saving/loading

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  • How do you get the logical xor of two variables in Python?

    - by Zach Hirsch
    How do you get the logical xor of two variables in Python? For example, I have two variables that I expect to be strings. I want to test that only one of them contains a True value (is not None or the empty string): str1 = raw_input("Enter string one:") str2 = raw_input("Enter string two:") if logical_xor(str1, str2): print "ok" else: print "bad" The ^ operator seems to be bitwise, and not defined on all objects: >>> 1 ^ 1 0 >>> 2 ^ 1 3 >>> "abc" ^ "" Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for ^: 'str' and 'str'

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  • Drawing two orthogonal strings in 3d space in Android Canvas?

    - by hasanghaforian
    I want to draw two strings in canvas.First string must be rotated around Y axis,for example 45 degrees.Second string must be start at the end of first string and also it must be orthogonal to first string. This is my code: String text = "In the"; float textWidth = redPaint.measureText(text); Matrix m0 = new Matrix(); Matrix m1 = new Matrix(); Matrix m2 = new Matrix(); mCamera = new Camera(); canvas.setMatrix(null); canvas.save(); mCamera.rotateY(45); mCamera.getMatrix(m0); m0.preTranslate(-100, -100); m0.postTranslate(100, 100); canvas.setMatrix(m0); canvas.drawText(text, 100, 100, redPaint); mCamera = new Camera(); mCamera.rotateY(90); mCamera.getMatrix(m1); m1.preTranslate(-textWidth - 100, -100); m1.postTranslate(textWidth + 100, 100); m2.setConcat(m1, m0); canvas.setMatrix(m2); canvas.drawText(text, 100 + textWidth, 100, greenPaint); But in result,only first string(text with red font)is visible. How can I do drawing two orthogonal strings in 3d space?

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  • Using OpenGL drawing operations in an object-oriented setting?

    - by Lion Kabob
    I've been plowing through basic shaders and whatnot for an application I'm writing, and I've been having trouble figuring out a high-level organization for the drawing calls. I'm thinking of having a singleton class which implements a number of basic drawing operations, taking data from "user" classes and passing that to the appropriate opengl calls. I'm wondering how people do this when writing their own applications, as the internet is chock full of basic "Your first shader" tutorials, but very little on suggested organization of drawing code. My particular environment is targeted at iPad/OpenGL ES 2.0, but I think the question stands for most environments.

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  • Printing gives unhandled exception. Access Denied

    - by Smoka
    Im newish to coding, currently on a Windows Forms App using CLI in VS10 Everything seems to work, my document shows fine in the Preview dialog but then crash's. Heres only the code that seems relevant private: System::Drawing::Printing::PrintDocument^ docPrint; private: System::Windows::Forms::PrintDialog^ dlgPrint; private: System::Windows::Forms::PrintPreviewDialog^ dlgPrintPreview; this->button2 = (gcnew System::Windows::Forms::Button()); this->docPrint = (gcnew System::Drawing::Printing::PrintDocument()); this->dlgPrint = (gcnew System::Windows::Forms::PrintDialog()); this->dlgPrintPreview = (gcnew System::Windows::Forms::PrintPreviewDialog()); this->button2->Location = System::Drawing::Point(152, 355); this->button2->Name = L"button2"; this->button2->Size = System::Drawing::Size(75, 23); this->button2->TabIndex = 53; this->button2->Text = L"Print"; this->button2->UseVisualStyleBackColor = true; this->button2->Click += gcnew System::EventHandler(this, &Form1::button2_Click_1); // // docPrint // this->docPrint->DocumentName = L"ResultsPage"; this->docPrint->PrintPage += gcnew System::Drawing::Printing::PrintPageEventHandler(this, &Form1::docPrint_PrintPage); // // dlgPrint // this->dlgPrint->Document = this->docPrint; this->dlgPrint->UseEXDialog = true; // // dlgPrintPreview // this->dlgPrintPreview->AutoScrollMargin = System::Drawing::Size(0, 0); this->dlgPrintPreview->AutoScrollMinSize = System::Drawing::Size(0, 0); this->dlgPrintPreview->ClientSize = System::Drawing::Size(400, 300); this->dlgPrintPreview->Document = this->docPrint; this->dlgPrintPreview->Enabled = true; this->dlgPrintPreview->Icon = (cli::safe_cast<System::Drawing::Icon^ >(resources->GetObject(L"dlgPrintPreview.Icon"))); this->dlgPrintPreview->Name = L"dlgPrintPreview"; this->dlgPrintPreview->Visible = false; this->dlgPrintPreview->Load += gcnew System::EventHandler(this, &Form1::dlgPrintPreview_Load); private: System::Void docPrint_PrintPage(System::Object^ sender, System::Drawing::Printing::PrintPageEventArgs^ e) { String ^ strDisplay = L"A Axis Rotations"; String ^ strDisplay2 = L"Centerline of Y" + CL_Y->Text + " + Z" + CL_Z->Text; String ^ strDisplay3 = L"Initial Position Y" + G54_Y->Text + " + Z" + G54_Z->Text; System::Drawing::Font ^ fntString = gcnew System::Drawing::Font(L"Times New Roman", 38, FontStyle::Bold); e->Graphics->DrawString(strDisplay, fntString, Brushes::Black, 200,20); e->Graphics->DrawString(strDisplay2, fntString, Brushes::Black, 80,150); e->Graphics->DrawString(strDisplay3, fntString, Brushes::Black, 80,220); e->Graphics->DrawString(Results->Text, fntString,Brushes::Black, 50,400); } private: System::Void button2_Click_1(System::Object^ sender, System::EventArgs^ e) { // docPrint->Print; dlgPrintPreview->ShowDialog(); } private: System::Void dlgPrintPreview_Load(System::Object^ sender, System::EventArgs^ e) { } Sorry if the formatting is ugly here.

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  • Why must "stride" in the System.Drawing.Bitmap constructor be a multiple of 4?

    - by Gorchestopher H
    I am writing an application that requires me to take a proprietary bitmap format (an MVTec Halcon HImage) and convert it into a System.Drawing.Bitmap in C#. The only proprietary functions given to me to help me do this involve me writing to file, except for the use of a "get pointer" function. This function is great, it gives me a pointer to the pixel data, the width, the height, and the type of the image. My issue is that when I create my System.Drawing.Bitmap using the constructor: new System.Drawing.Bitmap(width, height, stride, format, scan) I need to specify a "stride" that is a multiple of 4. This may be a problem as I am unsure what size bitmap my function will be hit with. Supposing I end up with a bitmap that is 111x111 pixels, I have no way to run this function other than adding a bogus column to my image or subtracting 3 columns. Is there a way I can sneak around this limitation?

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  • For Programmers familiar with ACM API? Drawing Initials [closed]

    - by user71992
    Possible Duplicate: For Programmers familiar with ACM API? Drawing Initials I came across an exercise (in the book "The Art and Science of Java" by Eric Roberts) that requires using only GArc and GLine classes to create a lettering library which draws your initials on the canvas. This should be made independent of the GLabel class. I'd like to know the correct approach to use in solving this problem. I'm not sure what I have so far is good enough (I'm thinking it's too long). The questions requires that I use a good Top-Down approach. Here's my code so far: //Passes letters to GLetter objects and draws them on the canvas package artScienceJavaExercises.chapter8; import acm.program.*; //import acm.graphics.*; public class DrawInitials extends GraphicsProgram{ public void init(){ resize(400,400); } public void run(){ //String let = readLine("Letter?: "); letter = new GLetter("l"); add(letter, (getWidth()-letter.getWidth()*2)/2, (getHeight()-letter.getHeight())/2); add(new GLetter("o"), (letter.getX()+letter.getWidth()), letter.getY()); } private GLetter letter; } //GLetter Class package artScienceJavaExercises.chapter8; import acm.graphics.*; import java.awt.*; public class GLetter extends GCompound{ private static final int ONE_THIRD = 30; private static final int ROW_2_HEIGHT = 40; private GArc[] arc = new GArc[4]; private GLine[] line = new GLine[24]; public GLetter(String s){ line[0] = new GLine(0,0, ONE_THIRD, 0); line[1] = new GLine(ONE_THIRD,0, ONE_THIRD*2, 0); line[2] = new GLine(ONE_THIRD*2,0, ONE_THIRD*3, 0); line[3] = new GLine(0,0, 0,ONE_THIRD); line[4] = new GLine(ONE_THIRD,0, ONE_THIRD, ONE_THIRD); line[5] = new GLine(ONE_THIRD*2,0, ONE_THIRD*2, ONE_THIRD); line[6] = new GLine(ONE_THIRD*3,0, ONE_THIRD*3, ONE_THIRD); line[7] = new GLine(0,ONE_THIRD, ONE_THIRD*2, ONE_THIRD); line[8] = new GLine(ONE_THIRD,ONE_THIRD, ONE_THIRD*2, ONE_THIRD); line[9] = new GLine(ONE_THIRD*2,ONE_THIRD, ONE_THIRD*3, ONE_THIRD); line[10] = new GLine(0,ONE_THIRD, 0, ONE_THIRD+ROW_2_HEIGHT); line[11] = new GLine(ONE_THIRD, ONE_THIRD, ONE_THIRD, ONE_THIRD+ROW_2_HEIGHT); line[12] = new GLine(ONE_THIRD*2,ONE_THIRD, ONE_THIRD*2, ONE_THIRD+ROW_2_HEIGHT); line[13] = new GLine(ONE_THIRD*3,ONE_THIRD, ONE_THIRD*3, ONE_THIRD+ROW_2_HEIGHT); line[14] = new GLine(0, ONE_THIRD+ROW_2_HEIGHT, ONE_THIRD, ONE_THIRD+ROW_2_HEIGHT); line[15] = new GLine(ONE_THIRD, ONE_THIRD+ROW_2_HEIGHT, ONE_THIRD*2, ONE_THIRD+ROW_2_HEIGHT); line[16] = new GLine(ONE_THIRD*2, ONE_THIRD+ROW_2_HEIGHT, ONE_THIRD*3, ONE_THIRD+ROW_2_HEIGHT); line[17] = new GLine(0, ONE_THIRD+ROW_2_HEIGHT, 0, ONE_THIRD*2+ROW_2_HEIGHT); line[18] = new GLine(ONE_THIRD, ONE_THIRD+ROW_2_HEIGHT, ONE_THIRD, ONE_THIRD*2+ROW_2_HEIGHT); line[19] = new GLine(ONE_THIRD*2, ONE_THIRD+ROW_2_HEIGHT, ONE_THIRD*2, ONE_THIRD*2+ROW_2_HEIGHT); line[20] = new GLine(ONE_THIRD*3, ONE_THIRD+ROW_2_HEIGHT, ONE_THIRD*3, ONE_THIRD*2+ROW_2_HEIGHT); line[21] = new GLine(0,ONE_THIRD*2+ROW_2_HEIGHT, ONE_THIRD, ONE_THIRD*2+ROW_2_HEIGHT); line[22] = new GLine(ONE_THIRD, ONE_THIRD*2+ROW_2_HEIGHT, ONE_THIRD*2, ONE_THIRD*2+ROW_2_HEIGHT); line[23] = new GLine(ONE_THIRD*2,ONE_THIRD*2+ROW_2_HEIGHT, ONE_THIRD*3, ONE_THIRD*2+ROW_2_HEIGHT); for(int i = 0; i<line.length; i++){ add(line[i]); line[i].setColor(Color.BLACK); line[i].setVisible(false); } arc[0] = new GArc(getWidth(), getHeight(), 106.699, 49.341); arc[1] = new GArc(getWidth(), getHeight(), 23.96, 49.341); arc[2] = new GArc(getWidth(), getHeight(), -23.96, -49.341); arc[3] = new GArc(0,0,getWidth(), getHeight(), -106.699, -49.341); for(int i = 0; i<arc.length; i++){ add(arc[i],0,0); arc[i].setColor(Color.BLACK); arc[i].setVisible(false); } paintLetter(s); } private void paintLetter(String s){ if (s.equalsIgnoreCase("l")){ turnOn(line[3]); turnOn(line[10]); turnOn(line[17]); turnOn(line[21]); turnOn(line[22]); turnOn(line[23]); } else if(s.equalsIgnoreCase("o")){ for(int i = 0; i<4; ++i){ turnOn(arc[i]); } turnOn(line[1]); turnOn(line[10]); turnOn(line[13]); turnOn(line[22]); } } private void turnOn(GObject g){ g.setVisible(true); } } I created a class (GLetter.java) with arrays for GArc and GLine objects. They are positioned in certain ways thereby turning certain Glines and/or GArcs on or off (changing visiblity) would create a pattern for a letter. This Gletter uses the if/else statements to determine which pattern to create - this makes me feel my code is too long. There is another class (DrawInitials.java) that simulates a GraphicsProgram and allows the user to pass certain letters as arguments to the GLetter object. I've used 'L' and 'O' as examples. However, I posted this because I'm not sure I'm using the right approach. That's why I need your help. I feel MY CODE IS TOO LONG! The code above is not the complete project...it only draws letters 'L' and 'O' for now.

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  • Optimizing Solaris 11 SHA-1 on Intel Processors

    - by danx
    SHA-1 is a "hash" or "digest" operation that produces a 160 bit (20 byte) checksum value on arbitrary data, such as a file. It is intended to uniquely identify text and to verify it hasn't been modified. Max Locktyukhin and others at Intel have improved the performance of the SHA-1 digest algorithm using multiple techniques. This code has been incorporated into Solaris 11 and is available in the Solaris Crypto Framework via the libmd(3LIB), the industry-standard libpkcs11(3LIB) library, and Solaris kernel module sha1. The optimized code is used automatically on systems with a x86 CPU supporting SSSE3 (Intel Supplemental SSSE3). Intel microprocessor architectures that support SSSE3 include Nehalem, Westmere, Sandy Bridge microprocessor families. Further optimizations are available for microprocessors that support AVX (such as Sandy Bridge). Although SHA-1 is considered obsolete because of weaknesses found in the SHA-1 algorithm—NIST recommends using at least SHA-256, SHA-1 is still widely used and will be with us for awhile more. Collisions (the same SHA-1 result for two different inputs) can be found with moderate effort. SHA-1 is used heavily though in SSL/TLS, for example. And SHA-1 is stronger than the older MD5 digest algorithm, another digest option defined in SSL/TLS. Optimizations Review SHA-1 operates by reading an arbitrary amount of data. The data is read in 512 bit (64 byte) blocks (the last block is padded in a specific way to ensure it's a full 64 bytes). Each 64 byte block has 80 "rounds" of calculations (consisting of a mixture of "ROTATE-LEFT", "AND", and "XOR") applied to the block. Each round produces a 32-bit intermediate result, called W[i]. Here's what each round operates: The first 16 rounds, rounds 0 to 15, read the 512 bit block 32 bits at-a-time. These 32 bits is used as input to the round. The remaining rounds, rounds 16 to 79, use the results from the previous rounds as input. Specifically for round i it XORs the results of rounds i-3, i-8, i-14, and i-16 and rotates the result left 1 bit. The remaining calculations for the round is a series of AND, XOR, and ROTATE-LEFT operators on the 32-bit input and some constants. The 32-bit result is saved as W[i] for round i. The 32-bit result of the final round, W[79], is the SHA-1 checksum. Optimization: Vectorization The first 16 rounds can be vectorized (computed in parallel) because they don't depend on the output of a previous round. As for the remaining rounds, because of step 2 above, computing round i depends on the results of round i-3, W[i-3], one can vectorize 3 rounds at-a-time. Max Locktyukhin found through simple factoring, explained in detail in his article referenced below, that the dependencies of round i on the results of rounds i-3, i-8, i-14, and i-16 can be replaced instead with dependencies on the results of rounds i-6, i-16, i-28, and i-32. That is, instead of initializing intermediate result W[i] with: W[i] = (W[i-3] XOR W[i-8] XOR W[i-14] XOR W[i-16]) ROTATE-LEFT 1 Initialize W[i] as follows: W[i] = (W[i-6] XOR W[i-16] XOR W[i-28] XOR W[i-32]) ROTATE-LEFT 2 That means that 6 rounds could be vectorized at once, with no additional calculations, instead of just 3! This optimization is independent of Intel or any other microprocessor architecture, although the microprocessor has to support vectorization to use it, and exploits one of the weaknesses of SHA-1. Optimization: SSSE3 Intel SSSE3 makes use of 16 %xmm registers, each 128 bits wide. The 4 32-bit inputs to a round, W[i-6], W[i-16], W[i-28], W[i-32], all fit in one %xmm register. The following code snippet, from Max Locktyukhin's article, converted to ATT assembly syntax, computes 4 rounds in parallel with just a dozen or so SSSE3 instructions: movdqa W_minus_04, W_TMP pxor W_minus_28, W // W equals W[i-32:i-29] before XOR // W = W[i-32:i-29] ^ W[i-28:i-25] palignr $8, W_minus_08, W_TMP // W_TMP = W[i-6:i-3], combined from // W[i-4:i-1] and W[i-8:i-5] vectors pxor W_minus_16, W // W = (W[i-32:i-29] ^ W[i-28:i-25]) ^ W[i-16:i-13] pxor W_TMP, W // W = (W[i-32:i-29] ^ W[i-28:i-25] ^ W[i-16:i-13]) ^ W[i-6:i-3]) movdqa W, W_TMP // 4 dwords in W are rotated left by 2 psrld $30, W // rotate left by 2 W = (W >> 30) | (W << 2) pslld $2, W_TMP por W, W_TMP movdqa W_TMP, W // four new W values W[i:i+3] are now calculated paddd (K_XMM), W_TMP // adding 4 current round's values of K movdqa W_TMP, (WK(i)) // storing for downstream GPR instructions to read A window of the 32 previous results, W[i-1] to W[i-32] is saved in memory on the stack. This is best illustrated with a chart. Without vectorization, computing the rounds is like this (each "R" represents 1 round of SHA-1 computation): RRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR With vectorization, 4 rounds can be computed in parallel: RRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRR RRRRRRRRRRRRRRRRRRRR Optimization: AVX The new "Sandy Bridge" microprocessor architecture, which supports AVX, allows another interesting optimization. SSSE3 instructions have two operands, a input and an output. AVX allows three operands, two inputs and an output. In many cases two SSSE3 instructions can be combined into one AVX instruction. The difference is best illustrated with an example. Consider these two instructions from the snippet above: pxor W_minus_16, W // W = (W[i-32:i-29] ^ W[i-28:i-25]) ^ W[i-16:i-13] pxor W_TMP, W // W = (W[i-32:i-29] ^ W[i-28:i-25] ^ W[i-16:i-13]) ^ W[i-6:i-3]) With AVX they can be combined in one instruction: vpxor W_minus_16, W, W_TMP // W = (W[i-32:i-29] ^ W[i-28:i-25] ^ W[i-16:i-13]) ^ W[i-6:i-3]) This optimization is also in Solaris, although Sandy Bridge-based systems aren't widely available yet. As an exercise for the reader, AVX also has 256-bit media registers, %ymm0 - %ymm15 (a superset of 128-bit %xmm0 - %xmm15). Can %ymm registers be used to parallelize the code even more? Optimization: Solaris-specific In addition to using the Intel code described above, I performed other minor optimizations to the Solaris SHA-1 code: Increased the digest(1) and mac(1) command's buffer size from 4K to 64K, as previously done for decrypt(1) and encrypt(1). This size is well suited for ZFS file systems, but helps for other file systems as well. Optimized encode functions, which byte swap the input and output data, to copy/byte-swap 4 or 8 bytes at-a-time instead of 1 byte-at-a-time. Enhanced the Solaris mdb(1) and kmdb(1) debuggers to display all 16 %xmm and %ymm registers (mdb "$x" command). Previously they only displayed the first 8 that are available in 32-bit mode. Can't optimize if you can't debug :-). Changed the SHA-1 code to allow processing in "chunks" greater than 2 Gigabytes (64-bits) Performance I measured performance on a Sun Ultra 27 (which has a Nehalem-class Xeon 5500 Intel W3570 microprocessor @3.2GHz). Turbo mode is disabled for consistent performance measurement. Graphs are better than words and numbers, so here they are: The first graph shows the Solaris digest(1) command before and after the optimizations discussed here, contained in libmd(3LIB). I ran the digest command on a half GByte file in swapfs (/tmp) and execution time decreased from 1.35 seconds to 0.98 seconds. The second graph shows the the results of an internal microbenchmark that uses the Solaris libpkcs11(3LIB) library. The operations are on a 128 byte buffer with 10,000 iterations. The results show operations increased from 320,000 to 416,000 operations per second. Finally the third graph shows the results of an internal kernel microbenchmark that uses the Solaris /kernel/crypto/amd64/sha1 module. The operations are on a 64Kbyte buffer with 100 iterations. third graph shows the results of an internal kernel microbenchmark that uses the Solaris /kernel/crypto/amd64/sha1 module. The operations are on a 64Kbyte buffer with 100 iterations. The results show for 1 kernel thread, operations increased from 410 to 600 MBytes/second. For 8 kernel threads, operations increase from 1540 to 1940 MBytes/second. Availability This code is in Solaris 11 FCS. It is available in the 64-bit libmd(3LIB) library for 64-bit programs and is in the Solaris kernel. You must be running hardware that supports Intel's SSSE3 instructions (for example, Intel Nehalem, Westmere, or Sandy Bridge microprocessor architectures). The easiest way to determine if SSSE3 is available is with the isainfo(1) command. For example, nehalem $ isainfo -v $ isainfo -v 64-bit amd64 applications sse4.2 sse4.1 ssse3 popcnt tscp ahf cx16 sse3 sse2 sse fxsr mmx cmov amd_sysc cx8 tsc fpu 32-bit i386 applications sse4.2 sse4.1 ssse3 popcnt tscp ahf cx16 sse3 sse2 sse fxsr mmx cmov sep cx8 tsc fpu If the output also shows "avx", the Solaris executes the even-more optimized 3-operand AVX instructions for SHA-1 mentioned above: sandybridge $ isainfo -v 64-bit amd64 applications avx xsave pclmulqdq aes sse4.2 sse4.1 ssse3 popcnt tscp ahf cx16 sse3 sse2 sse fxsr mmx cmov amd_sysc cx8 tsc fpu 32-bit i386 applications avx xsave pclmulqdq aes sse4.2 sse4.1 ssse3 popcnt tscp ahf cx16 sse3 sse2 sse fxsr mmx cmov sep cx8 tsc fpu No special configuration or setup is needed to take advantage of this code. Solaris libraries and kernel automatically determine if it's running on SSSE3 or AVX-capable machines and execute the correctly-tuned code for that microprocessor. Summary The Solaris 11 Crypto Framework, via the sha1 kernel module and libmd(3LIB) and libpkcs11(3LIB) libraries, incorporated a useful SHA-1 optimization from Intel for SSSE3-capable microprocessors. As with other Solaris optimizations, they come automatically "under the hood" with the current Solaris release. References "Improving the Performance of the Secure Hash Algorithm (SHA-1)" by Max Locktyukhin (Intel, March 2010). The source for these SHA-1 optimizations used in Solaris "SHA-1", Wikipedia Good overview of SHA-1 FIPS 180-1 SHA-1 standard (FIPS, 1995) NIST Comments on Cryptanalytic Attacks on SHA-1 (2005, revised 2006)

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  • How to write test cases for drawing text / string in a box ?

    - by Madhup
    Hi, I am drawing strings in a rectangular frame. The string is drawing perfectly. Now I need to write test cases using sentesting kit. I have no ideas from where I should start. For help I have also seen the iPhone sample calculator application But still out of sorts. Any body having ideas please help. Thanks, Madhup

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  • How is the default constructor of System.Drawing.Graphics removed?

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    When I try to create an object of Graphics, why doesn't the following work? System.Drawing.Graphics graphicsObj = new System.Drawing.Graphics(); (I am aware that I could create a private System.Windows.Forms.Panel Obj; and then do CreateGraphics() if I wanted it to work) I tried to find a custom constructor for Graphics, but I couldn't find one. Where did Microsoft define it, or how did it block it?

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