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

Copying buffers


The two functions clEnqueueCopyBuffer and clEnqueueCopyBufferRect enable the application to copy data between two OpenCL buffer objects. It is equivalent to reading the buffer back from device to host and then writing it back to a destination cl_mem object. This mechanism is provided by these copy buffer routines:

cl_int 
clEnqueueCopyBuffer(cl_command_queue command_queue,cl_mem src_buffer,cl_mem dst_buffer,size_t src_offset, size_t dst_offset,size_t size,cl_uint num_events_in_wait_list,const cl_event *event_wait_list,cl_event *event)

This OpenCL API enqueue's a command to copy a cl_mem buffer object identified by src_buffer to another cl_mem object destination buffer, dst_buffer. Remaining parameters like offset and events are similar to the one in clEnqueue[Read|Write]Buffer routines.

Similarly if one wants to copy only a small rectangular region in the cl_mem buffer then he can use the API:

cl_int 
clEnqueueCopyBufferRect(cl_command_queue command_queue,cl_mem src_buffer,cl_mem...