Posts Tagged ‘Qt’

Qt Creator OpenCL Syntax Highlighting

July 7th, 2011

With highlighting for Gedit, I was happy to give you the convenience of a nice editor to work on OpenCL-files. But it seems that one of the most popular IDEs for C++-programming is Qt Creator. So you receive another free syntax highlighter. You need at least Qt Creator 2.1.0.

The people of Qt have written everything you need to know about their Syntax highlighting, which was enough help to create this file. You see that they use the system of Kate, so logically this file works with this editor too.

In this article there is all you need to know to use Qt Creator with OpenCL.

Installing

First download the file to your computer.

Under Windows and OSX you need to copy this file to the directory \share\qtcreator\generic-highlighter\ in the Qt installation dir (i.e. c:\Qt\qtcreator-2.2.1\share\qtcreator\generic-highlighter\). Under Linux copy this file to ~/.kde/share/apps/katepart/syntax or to /usr/share/kde4/apps/katepart/syntax (all users). That’s all, have fun!

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Qt Hello World

May 28th, 2010

The earlier blog-post was about how to use Qt Creator with OpenCL. The examples are all around Images, but nowhere a simple Hello World. So here it is: AMD’s infamous OpenCL Hello World in Qt. Thank’s to linuxjunk for glueing the parts together.



int main(int argc, char *argv[]) {

    // Define the kernel. Take a good look what it does.
    QByteArray prog(
    "#pragma OPENCL EXTENSION cl_khr_byte_addressable_store : enable\n" \
    "__constant char hw[] = \"Hello World from Qt!\"; \n" \
    "__kernel void hello(__global char * out) {\n" \
    "  size_t tid = get_global_id(0); \n" \
    "  out[tid] = hw[tid]; \n" \
    "}\n"
    );

     // Get a context on the first available GPU.
     QCLContext context;
     if (!context.create(QCLDevice::GPU))
         qFatal("Could not create OpenCL context");

     // Allocate 100 bytes of memory on the Host.
     size_t mem_size = 100;
     char* outH = new char[mem_size];
     // Allocate buffer on the Device.
     QCLBuffer outCL = context.createBufferHost(outH, sizeof(char) * mem_size,
                                                QCLMemoryObject::WriteOnly);

     // Compile program against device
      QCLProgram program = context.buildProgramFromSourceCode(prog);

     // Create a kernel object, tell it we are using the kernel called "hello".
     QCLKernel kernel = program.createKernel("hello");

     // Set the necessary global memory. In this case it is the buffer-size.
     kernel.setGlobalWorkSize(outCL.size(), 1);

     // Turn on profiling.
     QCLCommandQueue queue = context.commandQueue();
     queue.setProfilingEnabled(true);

     // Queue the kernel up to run.
     // Give it an argument which is the memory we allocated above.
     QCLEvent event = kernel(outCL);

     // Use the event object above to block until processing has completed.
     event.waitForFinished();

     // Timing only works with profiling on. runTime is unsigned.
     printf(" time '%u'\n", event.runTime());

     // Read the results out of the shared memory area.
     outCL.read(outH, mem_size);

     // Write to screen.
     printf(" result = '%s'", outH);
}

Have fun! For a good explanation about how and why, just buy our book – available in Q4 2010.

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Using Qt Creator for OpenCL

May 25th, 2010

22-Dec-2010: updated article, now Qt’s OpenCL plugin needs Qt 4.6 or higher. Also provided binary for Linux-32 X86.

More and more ways are getting available to bring easy OpenCL to you. Most of the convenience libraries are wrappers for other languages, so it seems that C and C++ programmers have the hardest time. Since a while my favourite way to go is Qt: it is multi-platform, has a good IDE, is very extensive, has good multi-core and OpenGL-support and… has an extension for OpenCL: http://labs.trolltech.com/blogs/2010/04/07/using-opencl-with-qt

Other multi-platform choices are Anjuta, CodeLite, Netbeans and Eclipse. I will discuss them later, but wanted to give Qt an advantage because it also simplifies your OpenCL-development. While it is great for learning OpenCL-concepts, please know that the the commercial version costs you at least €2995,- a year. I must also warn the plugin is still in beta.

My own build (Ubuntu 10.10 X86-32, QT 4.7, NVIDIA) can be downloaded here: http://dl.dropbox.com/u/13708312/lib_QtOpenCL_Ubuntu32_Qt4.7_2010.12.22.zip (22 Dec 2010). Use at your own risk! It should work on all 32bit X86 Linux-distributions. Below describes how it can be built.

StreamComputing.eu is not affiliated with Qt.

Getting it all

Qt Creator is available in most Linux-repositories: install packages ‘qtcreator’ and ‘qt4-qmake’. For Windows, MAC and the other Linux-distributions there are installers available: http://qt.nokia.com/downloads. People who are not familiar with Qt, really should take a look around on http://qt.nokia.com/.

You can get the source for the plugin QtOpenCL, by using GIT:

git clone http://git.gitorious.org/qt-labs/opencl.git QtOpenCL

See http://qt.gitorious.org/qt-labs/opencl for more information about the status of the project.

You can download it here: http://dl.dropbox.com/u/13708312/QtOpenCL_2010.12.22.zip (22 Dec 2010)

Building the plugin

For Linux and MAC you need to have the ‘build-essentials’. For Windows it might be a lot harder, since you need make, gcc and a lot of other build-tools which are not easily packaged for the Windows-OS. If you’ve made a win32-binary and/or a Windows-specific how-to, let me know.

You might have seen that people have problems building the plugin. The trick is to use the options -qmake and -I (capital i) with the configure-script:

./configure -qmake <location of qmake 4.6 or higher> -I<location of directory CL with OpenCL-headers>
make

Notice the spaces. The program qmake is provided by Qt (package ‘qt4-qmake’), the OpenCL-headers by the SDK of ATI or NVidia (you’ll need the SDK anyway), or by Khronos. By example, on my laptop (NVIDIA, Ubuntu 32bit, with Qt 4.7):

./configure -qmake /usr/bin/qmake-qt4 -I/opt/NVIDIA_GPU_Computing_SDK_3.2/OpenCL/common/inc/
make

This should work. On MAC the directory is not CL, but OpenCL – I haven’t tested it if Qt took that into account.
After building , test it by setting a environment-setting “LD_LIBRARY_PATH” to the lib-directory in the plugin, and run the provided example-app ‘clinfo’. By example, on Linux:

export LD_LIBRARY_PATH=`pwd`/lib:$LD_LIBRARY_PATH
cd util/clinfo/
./clinfo

This should give you information about your OpenCL-setup. If you need further help, please go to the Qt forums.

Configuring Qt Creator

Now it’s time to make a new project with support for OpenCL. This has to be done in two steps.

First make a project and edit the .pro-file by adding the following:

LIBS     += -L<location of opencl-plugin>/lib -L<location of OpenCL-SDK libraries> -lOpenCL -lQtOpenCL

INCLUDEPATH += <location of opencl-plugin>/lib/\
<location of OpenCL-SDK include-files>\
<location of opencl-plugin>/src/opencl/

By example:

LIBS     += -L/opt/qt-opencl/lib -L/usr/local/cuda/lib -lOpenCL -lQtOpenCL
INCLUDEPATH += /opt/qt-opencl/lib/\
/usr/local/cuda/include/\
/opt/qt-opencl/src/opencl/

The following screenshot shows how it could look like:

Second we edit (or add) the LD_LIBRARY_PATH in the project-settings (click on ‘Projects’ as seen in screenshot):

/usr/lib/qtcreator:location of opencl-plugin>:<location of OpenCL-SDK libraries>:

By example:

/usr/lib/qtcreator:/opt/qt-opencl/lib:/usr/local/cuda/lib:

As you see, we now also need to have the Qt-creator-libraries and SDK-libraries included.
The following screenshot shows the edit-field for the project-environment:

Testing your setup

Just add something from the clinfo-source to your project:

printf("OpenCL Platforms:\n"); QList platforms = QCLPlatform::platforms(); foreach (QCLPlatform platform, platforms) { printf("    Platform ID       : %ld\n", long(platform.platformId())); printf("    Profile           : %s\n", platform.profile().toLatin1().constData()); printf("    Version           : %s\n", platform.version().toLatin1().constData()); printf("    Name              : %s\n", platform.name().toLatin1().constData()); printf("    Vendor            : %s\n", platform.vendor().toLatin1().constData()); printf("    Extension Suffix  : %s\n", platform.extensionSuffix().toLatin1().constData());printf("    Extensions        :\n"); QStringList extns = platform.extensions(); foreach (QString ext, extns) printf("        %s\n", ext.toLatin1().constData()); printf("\n");

If it gives errors during programming (underlined includes, etc), focus on INCLUDEPATH in the project-file. If it complaints when building the application, focus on LIBS. If it complaints when running the successfully built application, focus on LD_LIBRARY_PATH.

Ok, it is maybe not that easy to get it running, but I promise it gets easier after this. Check out our Hello World, the provided examples and http://doc.qt.nokia.com/opencl-snapshot/ to start building.

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