Book Image

OpenCL Programming by Example

Book Image

OpenCL Programming by Example

Overview of this book

Research in parallel programming has been a mainstream topic for a decade, and will continue to be so for many decades to come. Many parallel programming standards and frameworks exist, but only take into account one type of hardware architecture. Today computing platforms come with many heterogeneous devices. OpenCL provides royalty free standard to program heterogeneous hardware. This guide offers you a compact coverage of all the major topics of OpenCL programming. It explains optimization techniques and strategies in-depth, using illustrative examples and also provides case studies from diverse fields. Beginners and advanced application developers will find this book very useful. Beginning with the discussion of the OpenCL models, this book explores their architectural view, programming interfaces and primitives. It slowly demystifies the process of identifying the data and task parallelism in diverse algorithms. It presents examples from different domains to show how the problems within different domains can be solved more efficiently using OpenCL. You will learn about parallel sorting, histogram generation, JPEG compression, linear and parabolic regression and k-nearest neighborhood, a clustering algorithm in pattern recognition. Following on from this, optimization strategies are explained with matrix multiplication examples. You will also learn how to do an interoperation of OpenGL and OpenCL. "OpenCL Programming by Example" explains OpenCL in the simplest possible language, which beginners will find it easy to understand. Developers and programmers from different domains who want to achieve acceleration for their applications will find this book very useful.
Table of Contents (18 chapters)
OpenCL Programming by Example
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Implementing Interoperation


To use the Interoperation function we need to include the cl_gl.h header file. This header contains declaration of the required function for interoperation.

Detecting if OpenCL-OpenGL Interoperation is supported

Before discussing other implementation steps, we try to detect whether the current environment supports this interoperation. We use the OpenCL API clGetDeviceInfo(…) for this purpose. The first call would get the total size needed to store the string (char*) returned by the second call. This string is a list of all the device extensions that are supported by the current environment. We then try to find from this list, whether it has an item called cl_khr_gl_sharing for Windows and Linux and cl_apple_gl_sharing for Mac. Its presence would indicate the support of OpenCL-OpenGL interoperation, otherwise not.

Find the size of device info string in a variable sizeOfExtensionString called which is of type size_t as follows:

size_t sizeOfExtensionString;
cl_int errorStatus...