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

Address space qualifiers


There are four different address space qualifiers supported by OpenCL. The address space qualifier is used in variable declarations to specify the region of memory to allocate the declared object. The following is the list of address qualifiers:

  • __global or global

  • __local or local

  • __constant or constant

  • __private or private

A data type object in a kernel program is allocated space in the specified address space qualifier. If no specifier is given then a generic address space is considered. For example all kernel function arguments and local variables will take a __private if no address space qualifier is specified. Image memory objects arguments of type image2d_t, image3d_t, image2d_array_t, image1d_t, image1d_buffer_t, and image1d_array_t refer to the __global address space. Address space qualifiers for return types are allowed only for pointer types.

The OpenCL memory model specifies the different memory regions. Each of these are categorized into the address space qualifier...