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 <span id="projectnumber">1.7.1</span>
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<div class="title">custom-context.cpp</div> </div>
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<div class="contents">
<p>This tutorial shows how you can use your own OpenCL contexts with ViennaCL.</p>
<p>We begin with including the necessary headers: </p>
<div class="fragment"><div class="line"><span class="comment">// System headers</span></div>
<div class="line"><span class="preprocessor">#include <iostream></span></div>
<div class="line"><span class="preprocessor">#include <string></span></div>
<div class="line"></div>
<div class="line"><span class="preprocessor">#ifndef VIENNACL_WITH_OPENCL</span></div>
<div class="line"><span class="preprocessor"> #define VIENNACL_WITH_OPENCL</span></div>
<div class="line"><span class="preprocessor">#endif</span></div>
<div class="line"></div>
<div class="line"></div>
<div class="line"><span class="comment">// ViennaCL headers</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="backend_8hpp.html">viennacl/ocl/backend.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="vector_8hpp.html">viennacl/vector.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="matrix_8hpp.html">viennacl/matrix.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="matrix__operations_8hpp.html">viennacl/linalg/matrix_operations.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="norm__2_8hpp.html">viennacl/linalg/norm_2.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="prod_8hpp.html">viennacl/linalg/prod.hpp</a>"</span></div>
</div><!-- fragment --> <h2>Defining a Compute Kernel</h2>
<p>In the following we define a custom compute kernel which computes an elementwise product of two vectors. <br/>
Input: v1 ... vector<br/>
v2 ... vector<br/>
Output: result ... vector<br/>
</p>
<p>Algorithm: set result[i] <- v1[i] * v2[i]<br/>
(in MATLAB notation this is 'result = v1 .* v2');<br/>
</p>
<div class="fragment"><div class="line"><span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">char</span> * my_compute_program =</div>
<div class="line"><span class="stringliteral">"__kernel void elementwise_prod(\n"</span></div>
<div class="line"><span class="stringliteral">" __global const float * vec1,\n"</span></div>
<div class="line"><span class="stringliteral">" __global const float * vec2, \n"</span></div>
<div class="line"><span class="stringliteral">" __global float * result,\n"</span></div>
<div class="line"><span class="stringliteral">" unsigned int size) \n"</span></div>
<div class="line"><span class="stringliteral">"{ \n"</span></div>
<div class="line"><span class="stringliteral">" for (unsigned int i = get_global_id(0); i < size; i += get_global_size(0))\n"</span></div>
<div class="line"><span class="stringliteral">" result[i] = vec1[i] * vec2[i];\n"</span></div>
<div class="line"><span class="stringliteral">"};\n"</span>;</div>
</div><!-- fragment --><p> With this let us go right to <a class="el" href="tests_2src_2bisect_8cpp.html#ae66f6b31b5ad750f1fe042a706a4e3d4">main()</a>: </p>
<div class="fragment"><div class="line"><span class="keywordtype">int</span> <a name="a0"></a><a class="code" href="tests_2src_2bisect_8cpp.html#ae66f6b31b5ad750f1fe042a706a4e3d4">main</a>()</div>
<div class="line">{</div>
<div class="line"> <span class="keyword">typedef</span> <span class="keywordtype">float</span> <a name="a1"></a><a class="code" href="fft__1d_8cpp.html#ad5c19ca4f47d3f8ec21232a5af2624e5">ScalarType</a>;</div>
</div><!-- fragment --> <h2>Part 1: Set up a custom context</h2>
<p>The following is rather lengthy because OpenCL is a fairly low-level framework. For comparison, the subsequent code explicitly performs the OpenCL setup that is done in the background within the 'custom_kernels'-tutorial </p>
<div class="fragment"><div class="line"> <span class="comment">//manually set up a custom OpenCL context:</span></div>
<div class="line"> std::vector<cl_device_id> device_id_array;</div>
<div class="line"></div>
<div class="line"> <span class="comment">//get all available devices</span></div>
<div class="line"> <a name="_a2"></a><a class="code" href="classviennacl_1_1ocl_1_1platform.html">viennacl::ocl::platform</a> pf;</div>
<div class="line"> std::cout << <span class="stringliteral">"Platform info: "</span> << pf.<a name="a3"></a><a class="code" href="classviennacl_1_1ocl_1_1platform.html#ac570aa63d292d47da2258136bef5f6e9">info</a>() << std::endl;</div>
<div class="line"> std::vector<viennacl::ocl::device> devices = pf.<a name="a4"></a><a class="code" href="classviennacl_1_1ocl_1_1platform.html#afaa563522ebe9ce7b80ef02c40e7fe31">devices</a>(CL_DEVICE_TYPE_DEFAULT);</div>
<div class="line"> std::cout << devices[0].name() << std::endl;</div>
<div class="line"> std::cout << <span class="stringliteral">"Number of devices for custom context: "</span> << devices.size() << std::endl;</div>
<div class="line"></div>
<div class="line"> <span class="comment">//set up context using all found devices:</span></div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<devices.size(); ++i)</div>
<div class="line"> {</div>
<div class="line"> device_id_array.push_back(devices[i].<span class="keywordtype">id</span>());</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"Creating context..."</span> << std::endl;</div>
<div class="line"> cl_int err;</div>
<div class="line"> cl_context my_context = clCreateContext(0, cl_uint(device_id_array.size()), &(device_id_array[0]), NULL, NULL, &err);</div>
<div class="line"> <a name="a5"></a><a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//create two Vectors:</span></div>
<div class="line"> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> vector_size = 10;</div>
<div class="line"> std::vector<ScalarType> vec1(vector_size);</div>
<div class="line"> std::vector<ScalarType> vec2(vector_size);</div>
<div class="line"> std::vector<ScalarType> result(vector_size);</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// fill the operands vec1 and vec2:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i<vector_size; ++i)</div>
<div class="line"> {</div>
<div class="line"> vec1[i] = <span class="keyword">static_cast<</span>ScalarType<span class="keyword">></span>(i);</div>
<div class="line"> vec2[i] = <span class="keyword">static_cast<</span>ScalarType<span class="keyword">></span>(vector_size-i);</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create memory in OpenCL context:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> cl_mem mem_vec1 = clCreateBuffer(my_context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, vector_size * <span class="keyword">sizeof</span>(ScalarType), &(vec1[0]), &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> cl_mem mem_vec2 = clCreateBuffer(my_context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, vector_size * <span class="keyword">sizeof</span>(ScalarType), &(vec2[0]), &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> cl_mem mem_result = clCreateBuffer(my_context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, vector_size * <span class="keyword">sizeof</span>(ScalarType), &(result[0]), &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create a command queue for each device:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"></div>
<div class="line"> std::vector<cl_command_queue> queues(devices.size());</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<devices.size(); ++i)</div>
<div class="line"> {</div>
<div class="line"> queues[i] = clCreateCommandQueue(my_context, devices[i].<span class="keywordtype">id</span>(), 0, &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create and build a program in the context:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> std::size_t source_len = std::string(my_compute_program).length();</div>
<div class="line"> cl_program my_prog = clCreateProgramWithSource(my_context, 1, &my_compute_program, &source_len, &err);</div>
<div class="line"> err = clBuildProgram(my_prog, 0, NULL, NULL, NULL, NULL);</div>
<div class="line"></div>
<div class="line"><span class="comment">/* char buffer[1024];</span></div>
<div class="line"><span class="comment"> cl_build_status status;</span></div>
<div class="line"><span class="comment"> clGetProgramBuildInfo(my_prog, devices[1].id(), CL_PROGRAM_BUILD_STATUS, sizeof(cl_build_status), &status, NULL);</span></div>
<div class="line"><span class="comment"> clGetProgramBuildInfo(my_prog, devices[1].id(), CL_PROGRAM_BUILD_LOG, sizeof(char)*1024, &buffer, NULL);</span></div>
<div class="line"><span class="comment"> std::cout << "Build Scalar: Err = " << err << " Status = " << status << std::endl;</span></div>
<div class="line"><span class="comment"> std::cout << "Log: " << buffer << std::endl;*/</span></div>
<div class="line"></div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create a kernel from the program:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="keyword">const</span> <span class="keywordtype">char</span> * kernel_name = <span class="stringliteral">"elementwise_prod"</span>;</div>
<div class="line"> cl_kernel my_kernel = clCreateKernel(my_prog, kernel_name, &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// Execute elementwise_prod kernel on first queue: result = vec1 .* vec2;</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> err = clSetKernelArg(my_kernel, 0, <span class="keyword">sizeof</span>(cl_mem), (<span class="keywordtype">void</span>*)&mem_vec1);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clSetKernelArg(my_kernel, 1, <span class="keyword">sizeof</span>(cl_mem), (<span class="keywordtype">void</span>*)&mem_vec2);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clSetKernelArg(my_kernel, 2, <span class="keyword">sizeof</span>(cl_mem), (<span class="keywordtype">void</span>*)&mem_result);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clSetKernelArg(my_kernel, 3, <span class="keyword">sizeof</span>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>), (<span class="keywordtype">void</span>*)&vector_size);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> std::size_t global_size = vector_size;</div>
<div class="line"> std::size_t local_size = vector_size;</div>
<div class="line"> err = clEnqueueNDRangeKernel(queues[0], my_kernel, 1, NULL, &global_size, &local_size, 0, NULL, NULL);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// Read and output result:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> err = clEnqueueReadBuffer(queues[0], mem_vec1, CL_TRUE, 0, <span class="keyword">sizeof</span>(ScalarType)*vector_size, &(vec1[0]), 0, NULL, NULL);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clEnqueueReadBuffer(queues[0], mem_result, CL_TRUE, 0, <span class="keyword">sizeof</span>(ScalarType)*vector_size, &(result[0]), 0, NULL, NULL);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec1 : "</span>;</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<vec1.size(); ++i)</div>
<div class="line"> std::cout << vec1[i] << <span class="stringliteral">" "</span>;</div>
<div class="line"> std::cout << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec2 : "</span>;</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<vec2.size(); ++i)</div>
<div class="line"> std::cout << vec2[i] << <span class="stringliteral">" "</span>;</div>
<div class="line"> std::cout << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"result: "</span>;</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<result.size(); ++i)</div>
<div class="line"> std::cout << result[i] << <span class="stringliteral">" "</span>;</div>
<div class="line"> std::cout << std::endl;</div>
</div><!-- fragment --> <h2>Part 2: Reuse Custom OpenCL Context with ViennaCL</h2>
<p>To let ViennaCL reuse the previously created context, we need to make it known to ViennaCL <em>before</em> any ViennaCL objects are created. We inject the custom context as the context with default id '0' when using <a class="el" href="namespaceviennacl_1_1ocl.html#acc1a7460a9ff237b7c0306c32c3d34c6" title="Convenience function for switching the current context. ">viennacl::ocl::switch_context()</a>. </p>
<div class="fragment"><div class="line"><a name="a6"></a><a class="code" href="namespaceviennacl_1_1ocl.html#add1725d48cfd159ce187e287369d1cdb">viennacl::ocl::setup_context</a>(0, my_context, device_id_array, queues);</div>
<div class="line"><a name="a7"></a><a class="code" href="namespaceviennacl_1_1ocl.html#acc1a7460a9ff237b7c0306c32c3d34c6">viennacl::ocl::switch_context</a>(0); <span class="comment">//activate the new context (only mandatory with context-id not equal to zero)</span></div>
</div><!-- fragment --><p> Check that ViennaCL really uses the new context: </p>
<div class="fragment"><div class="line">std::cout << <span class="stringliteral">"Existing context: "</span> << my_context << std::endl;</div>
<div class="line">std::cout << <span class="stringliteral">"ViennaCL uses context: "</span> << <a name="a8"></a><a class="code" href="namespaceviennacl_1_1ocl.html#a16fc917445ce2010e7b16fbc968771b7">viennacl::ocl::current_context</a>().<a name="a9"></a><a class="code" href="classviennacl_1_1ocl_1_1context.html#a611d95b11db04230f63e37bfeae911db">handle</a>().<a name="a10"></a><a class="code" href="classviennacl_1_1ocl_1_1handle.html#a5074caaee700015fc2d3b03540b01673">get</a>() << std::endl;</div>
</div><!-- fragment --><p> Wrap existing OpenCL objects into ViennaCL: </p>
<div class="fragment"><div class="line"><a name="_a11"></a><a class="code" href="classviennacl_1_1vector.html">viennacl::vector<ScalarType></a> vcl_vec1(mem_vec1, vector_size);</div>
<div class="line"><a class="code" href="classviennacl_1_1vector.html">viennacl::vector<ScalarType></a> vcl_vec2(mem_vec2, vector_size);</div>
<div class="line"><a class="code" href="classviennacl_1_1vector.html">viennacl::vector<ScalarType></a> vcl_result(mem_result, vector_size);</div>
<div class="line"><a name="_a12"></a><a class="code" href="classviennacl_1_1scalar.html">viennacl::scalar<ScalarType></a> vcl_s = 2.0;</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"Standard vector operations within ViennaCL:"</span> << std::endl;</div>
<div class="line">vcl_result = vcl_s * vcl_vec1 + vcl_vec2;</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"vec1 : "</span>;</div>
<div class="line">std::cout << vcl_vec1 << std::endl;</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"vec2 : "</span>;</div>
<div class="line">std::cout << vcl_vec2 << std::endl;</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"result: "</span>;</div>
<div class="line">std::cout << vcl_result << std::endl;</div>
</div><!-- fragment --><p> We can also reuse the existing elementwise_prod kernel. Therefore, we first have to make the existing program known to ViennaCL For more details on the three lines, see tutorial 'custom-kernels' </p>
<div class="fragment"><div class="line">std::cout << <span class="stringliteral">"Using existing kernel within the OpenCL backend of ViennaCL:"</span> << std::endl;</div>
<div class="line"><a name="_a13"></a><a class="code" href="classviennacl_1_1ocl_1_1program.html">viennacl::ocl::program</a> & my_vcl_prog = <a class="code" href="namespaceviennacl_1_1ocl.html#a16fc917445ce2010e7b16fbc968771b7">viennacl::ocl::current_context</a>().<a name="a14"></a><a class="code" href="classviennacl_1_1ocl_1_1context.html#a9094ac71f0cdf80df698c0c84ebb483d">add_program</a>(my_prog, <span class="stringliteral">"my_compute_program"</span>);</div>
<div class="line"><a name="_a15"></a><a class="code" href="classviennacl_1_1ocl_1_1kernel.html">viennacl::ocl::kernel</a> & my_vcl_kernel = my_vcl_prog.<a name="a16"></a><a class="code" href="classviennacl_1_1ocl_1_1program.html#aa4f77fdcd02daa7d71627dc20117ba75">add_kernel</a>(my_kernel, <span class="stringliteral">"elementwise_prod"</span>);</div>
<div class="line"><a name="a17"></a><a class="code" href="namespaceviennacl_1_1ocl.html#a5f2022f653ea1cf364d20e3ff84dcada">viennacl::ocl::enqueue</a>(my_vcl_kernel(vcl_vec1, vcl_vec2, vcl_result, static_cast<cl_uint>(vcl_vec1.size()))); <span class="comment">//Note that std::size_t might differ between host and device. Thus, a cast to cl_uint is necessary here.</span></div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"vec1 : "</span>;</div>
<div class="line">std::cout << vcl_vec1 << std::endl;</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"vec2 : "</span>;</div>
<div class="line">std::cout << vcl_vec2 << std::endl;</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"result: "</span>;</div>
<div class="line">std::cout << vcl_result << std::endl;</div>
</div><!-- fragment --><p> Since a linear piece of memory can be interpreted in several ways, we will now create a 3x3 row-major matrix out of the linear memory in mem_vec1/ The first three entries in vcl_vec2 and vcl_result are used to carry out matrix-vector products: </p>
<div class="fragment"><div class="line"><a name="_a18"></a><a class="code" href="classviennacl_1_1matrix.html">viennacl::matrix<ScalarType></a> vcl_matrix(mem_vec1, 3, 3);</div>
<div class="line"></div>
<div class="line">vcl_vec2.resize(3); <span class="comment">//note that the resize operation leads to new memory, thus vcl_vec2 is now at a different memory location (values are copied)</span></div>
<div class="line">vcl_result.resize(3); <span class="comment">//note that the resize operation leads to new memory, thus vcl_vec2 is now at a different memory location (values are copied)</span></div>
<div class="line">vcl_result = <a name="a19"></a><a class="code" href="namespaceviennacl_1_1linalg.html#aa18d10f8a90e38bd9ff43c650fc670ef">viennacl::linalg::prod</a>(vcl_matrix, vcl_vec2);</div>
<div class="line"></div>
<div class="line">std::cout << <span class="stringliteral">"result of matrix-vector product: "</span>;</div>
<div class="line">std::cout << vcl_result << std::endl;</div>
</div><!-- fragment --><p> Any further operations can be carried out in the same way. Just keep in mind that any resizing of vectors or matrices leads to a reallocation of the underlying memory buffer, through which the 'wrapper' is lost. </p>
<div class="fragment"><div class="line"> std::cout << <span class="stringliteral">"!!!! TUTORIAL COMPLETED SUCCESSFULLY !!!!"</span> << std::endl;</div>
<div class="line"></div>
<div class="line"> <span class="keywordflow">return</span> EXIT_SUCCESS;</div>
<div class="line">}</div>
</div><!-- fragment --> <h2>Full Example Code</h2>
<div class="fragment"><div class="line"><span class="comment">/* =========================================================================</span></div>
<div class="line"><span class="comment"> Copyright (c) 2010-2016, Institute for Microelectronics,</span></div>
<div class="line"><span class="comment"> Institute for Analysis and Scientific Computing,</span></div>
<div class="line"><span class="comment"> TU Wien.</span></div>
<div class="line"><span class="comment"> Portions of this software are copyright by UChicago Argonne, LLC.</span></div>
<div class="line"><span class="comment"></span></div>
<div class="line"><span class="comment"> -----------------</span></div>
<div class="line"><span class="comment"> ViennaCL - The Vienna Computing Library</span></div>
<div class="line"><span class="comment"> -----------------</span></div>
<div class="line"><span class="comment"></span></div>
<div class="line"><span class="comment"> Project Head: Karl Rupp rupp@iue.tuwien.ac.at</span></div>
<div class="line"><span class="comment"></span></div>
<div class="line"><span class="comment"> (A list of authors and contributors can be found in the PDF manual)</span></div>
<div class="line"><span class="comment"></span></div>
<div class="line"><span class="comment"> License: MIT (X11), see file LICENSE in the base directory</span></div>
<div class="line"><span class="comment">============================================================================= */</span></div>
<div class="line"></div>
<div class="line"><span class="comment">// System headers</span></div>
<div class="line"><span class="preprocessor">#include <iostream></span></div>
<div class="line"><span class="preprocessor">#include <string></span></div>
<div class="line"></div>
<div class="line"><span class="preprocessor">#ifndef VIENNACL_WITH_OPENCL</span></div>
<div class="line"><span class="preprocessor"> #define VIENNACL_WITH_OPENCL</span></div>
<div class="line"><span class="preprocessor">#endif</span></div>
<div class="line"></div>
<div class="line"></div>
<div class="line"><span class="comment">// ViennaCL headers</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="backend_8hpp.html">viennacl/ocl/backend.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="vector_8hpp.html">viennacl/vector.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="matrix_8hpp.html">viennacl/matrix.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="matrix__operations_8hpp.html">viennacl/linalg/matrix_operations.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="norm__2_8hpp.html">viennacl/linalg/norm_2.hpp</a>"</span></div>
<div class="line"><span class="preprocessor">#include "<a class="code" href="prod_8hpp.html">viennacl/linalg/prod.hpp</a>"</span></div>
<div class="line"></div>
<div class="line"></div>
<div class="line"></div>
<div class="line"><span class="keyword">static</span> <span class="keyword">const</span> <span class="keywordtype">char</span> * my_compute_program =</div>
<div class="line"><span class="stringliteral">"__kernel void elementwise_prod(\n"</span></div>
<div class="line"><span class="stringliteral">" __global const float * vec1,\n"</span></div>
<div class="line"><span class="stringliteral">" __global const float * vec2, \n"</span></div>
<div class="line"><span class="stringliteral">" __global float * result,\n"</span></div>
<div class="line"><span class="stringliteral">" unsigned int size) \n"</span></div>
<div class="line"><span class="stringliteral">"{ \n"</span></div>
<div class="line"><span class="stringliteral">" for (unsigned int i = get_global_id(0); i < size; i += get_global_size(0))\n"</span></div>
<div class="line"><span class="stringliteral">" result[i] = vec1[i] * vec2[i];\n"</span></div>
<div class="line"><span class="stringliteral">"};\n"</span>;</div>
<div class="line"></div>
<div class="line"><span class="keywordtype">int</span> <a class="code" href="tests_2src_2bisect_8cpp.html#ae66f6b31b5ad750f1fe042a706a4e3d4">main</a>()</div>
<div class="line">{</div>
<div class="line"> <span class="keyword">typedef</span> <span class="keywordtype">float</span> <a class="code" href="fft__1d_8cpp.html#ad5c19ca4f47d3f8ec21232a5af2624e5">ScalarType</a>;</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//manually set up a custom OpenCL context:</span></div>
<div class="line"> std::vector<cl_device_id> device_id_array;</div>
<div class="line"></div>
<div class="line"> <span class="comment">//get all available devices</span></div>
<div class="line"> <a class="code" href="classviennacl_1_1ocl_1_1platform.html">viennacl::ocl::platform</a> pf;</div>
<div class="line"> std::cout << <span class="stringliteral">"Platform info: "</span> << pf.<a class="code" href="classviennacl_1_1ocl_1_1platform.html#ac570aa63d292d47da2258136bef5f6e9">info</a>() << std::endl;</div>
<div class="line"> std::vector<viennacl::ocl::device> devices = pf.<a class="code" href="classviennacl_1_1ocl_1_1platform.html#afaa563522ebe9ce7b80ef02c40e7fe31">devices</a>(CL_DEVICE_TYPE_DEFAULT);</div>
<div class="line"> std::cout << devices[0].name() << std::endl;</div>
<div class="line"> std::cout << <span class="stringliteral">"Number of devices for custom context: "</span> << devices.size() << std::endl;</div>
<div class="line"></div>
<div class="line"> <span class="comment">//set up context using all found devices:</span></div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<devices.size(); ++i)</div>
<div class="line"> {</div>
<div class="line"> device_id_array.push_back(devices[i].<span class="keywordtype">id</span>());</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"Creating context..."</span> << std::endl;</div>
<div class="line"> cl_int err;</div>
<div class="line"> cl_context my_context = clCreateContext(0, cl_uint(device_id_array.size()), &(device_id_array[0]), NULL, NULL, &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//create two Vectors:</span></div>
<div class="line"> <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> vector_size = 10;</div>
<div class="line"> std::vector<ScalarType> vec1(vector_size);</div>
<div class="line"> std::vector<ScalarType> vec2(vector_size);</div>
<div class="line"> std::vector<ScalarType> result(vector_size);</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// fill the operands vec1 and vec2:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="keywordflow">for</span> (<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> i=0; i<vector_size; ++i)</div>
<div class="line"> {</div>
<div class="line"> vec1[i] = <span class="keyword">static_cast<</span>ScalarType<span class="keyword">></span>(i);</div>
<div class="line"> vec2[i] = <span class="keyword">static_cast<</span>ScalarType<span class="keyword">></span>(vector_size-i);</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create memory in OpenCL context:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> cl_mem mem_vec1 = clCreateBuffer(my_context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, vector_size * <span class="keyword">sizeof</span>(ScalarType), &(vec1[0]), &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> cl_mem mem_vec2 = clCreateBuffer(my_context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, vector_size * <span class="keyword">sizeof</span>(ScalarType), &(vec2[0]), &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> cl_mem mem_result = clCreateBuffer(my_context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, vector_size * <span class="keyword">sizeof</span>(ScalarType), &(result[0]), &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create a command queue for each device:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"></div>
<div class="line"> std::vector<cl_command_queue> queues(devices.size());</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<devices.size(); ++i)</div>
<div class="line"> {</div>
<div class="line"> queues[i] = clCreateCommandQueue(my_context, devices[i].<span class="keywordtype">id</span>(), 0, &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> }</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create and build a program in the context:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> std::size_t source_len = std::string(my_compute_program).length();</div>
<div class="line"> cl_program my_prog = clCreateProgramWithSource(my_context, 1, &my_compute_program, &source_len, &err);</div>
<div class="line"> err = clBuildProgram(my_prog, 0, NULL, NULL, NULL, NULL);</div>
<div class="line"></div>
<div class="line"><span class="comment">/* char buffer[1024];</span></div>
<div class="line"><span class="comment"> cl_build_status status;</span></div>
<div class="line"><span class="comment"> clGetProgramBuildInfo(my_prog, devices[1].id(), CL_PROGRAM_BUILD_STATUS, sizeof(cl_build_status), &status, NULL);</span></div>
<div class="line"><span class="comment"> clGetProgramBuildInfo(my_prog, devices[1].id(), CL_PROGRAM_BUILD_LOG, sizeof(char)*1024, &buffer, NULL);</span></div>
<div class="line"><span class="comment"> std::cout << "Build Scalar: Err = " << err << " Status = " << status << std::endl;</span></div>
<div class="line"><span class="comment"> std::cout << "Log: " << buffer << std::endl;*/</span></div>
<div class="line"></div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// create a kernel from the program:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="keyword">const</span> <span class="keywordtype">char</span> * kernel_name = <span class="stringliteral">"elementwise_prod"</span>;</div>
<div class="line"> cl_kernel my_kernel = clCreateKernel(my_prog, kernel_name, &err);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// Execute elementwise_prod kernel on first queue: result = vec1 .* vec2;</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> err = clSetKernelArg(my_kernel, 0, <span class="keyword">sizeof</span>(cl_mem), (<span class="keywordtype">void</span>*)&mem_vec1);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clSetKernelArg(my_kernel, 1, <span class="keyword">sizeof</span>(cl_mem), (<span class="keywordtype">void</span>*)&mem_vec2);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clSetKernelArg(my_kernel, 2, <span class="keyword">sizeof</span>(cl_mem), (<span class="keywordtype">void</span>*)&mem_result);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clSetKernelArg(my_kernel, 3, <span class="keyword">sizeof</span>(<span class="keywordtype">unsigned</span> <span class="keywordtype">int</span>), (<span class="keywordtype">void</span>*)&vector_size);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> std::size_t global_size = vector_size;</div>
<div class="line"> std::size_t local_size = vector_size;</div>
<div class="line"> err = clEnqueueNDRangeKernel(queues[0], my_kernel, 1, NULL, &global_size, &local_size, 0, NULL, NULL);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> <span class="comment">// Read and output result:</span></div>
<div class="line"> <span class="comment">//</span></div>
<div class="line"> err = clEnqueueReadBuffer(queues[0], mem_vec1, CL_TRUE, 0, <span class="keyword">sizeof</span>(ScalarType)*vector_size, &(vec1[0]), 0, NULL, NULL);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"> err = clEnqueueReadBuffer(queues[0], mem_result, CL_TRUE, 0, <span class="keyword">sizeof</span>(ScalarType)*vector_size, &(result[0]), 0, NULL, NULL);</div>
<div class="line"> <a class="code" href="error_8hpp.html#a44f070f54255e72eb40c75ebd72ea602">VIENNACL_ERR_CHECK</a>(err);</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec1 : "</span>;</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<vec1.size(); ++i)</div>
<div class="line"> std::cout << vec1[i] << <span class="stringliteral">" "</span>;</div>
<div class="line"> std::cout << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec2 : "</span>;</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<vec2.size(); ++i)</div>
<div class="line"> std::cout << vec2[i] << <span class="stringliteral">" "</span>;</div>
<div class="line"> std::cout << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"result: "</span>;</div>
<div class="line"> <span class="keywordflow">for</span> (std::size_t i=0; i<result.size(); ++i)</div>
<div class="line"> std::cout << result[i] << <span class="stringliteral">" "</span>;</div>
<div class="line"> std::cout << std::endl;</div>
<div class="line"></div>
<div class="line"> <a class="code" href="namespaceviennacl_1_1ocl.html#add1725d48cfd159ce187e287369d1cdb">viennacl::ocl::setup_context</a>(0, my_context, device_id_array, queues);</div>
<div class="line"> <a class="code" href="namespaceviennacl_1_1ocl.html#acc1a7460a9ff237b7c0306c32c3d34c6">viennacl::ocl::switch_context</a>(0); <span class="comment">//activate the new context (only mandatory with context-id not equal to zero)</span></div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"Existing context: "</span> << my_context << std::endl;</div>
<div class="line"> std::cout << <span class="stringliteral">"ViennaCL uses context: "</span> << <a class="code" href="namespaceviennacl_1_1ocl.html#a16fc917445ce2010e7b16fbc968771b7">viennacl::ocl::current_context</a>().<a class="code" href="classviennacl_1_1ocl_1_1context.html#a611d95b11db04230f63e37bfeae911db">handle</a>().<a class="code" href="classviennacl_1_1ocl_1_1handle.html#a5074caaee700015fc2d3b03540b01673">get</a>() << std::endl;</div>
<div class="line"></div>
<div class="line"> <a class="code" href="classviennacl_1_1vector.html">viennacl::vector<ScalarType></a> vcl_vec1(mem_vec1, vector_size);</div>
<div class="line"> <a class="code" href="classviennacl_1_1vector.html">viennacl::vector<ScalarType></a> vcl_vec2(mem_vec2, vector_size);</div>
<div class="line"> <a class="code" href="classviennacl_1_1vector.html">viennacl::vector<ScalarType></a> vcl_result(mem_result, vector_size);</div>
<div class="line"> <a class="code" href="classviennacl_1_1scalar.html">viennacl::scalar<ScalarType></a> vcl_s = 2.0;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"Standard vector operations within ViennaCL:"</span> << std::endl;</div>
<div class="line"> vcl_result = vcl_s * vcl_vec1 + vcl_vec2;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec1 : "</span>;</div>
<div class="line"> std::cout << vcl_vec1 << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec2 : "</span>;</div>
<div class="line"> std::cout << vcl_vec2 << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"result: "</span>;</div>
<div class="line"> std::cout << vcl_result << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"Using existing kernel within the OpenCL backend of ViennaCL:"</span> << std::endl;</div>
<div class="line"> <a class="code" href="classviennacl_1_1ocl_1_1program.html">viennacl::ocl::program</a> & my_vcl_prog = <a class="code" href="namespaceviennacl_1_1ocl.html#a16fc917445ce2010e7b16fbc968771b7">viennacl::ocl::current_context</a>().<a class="code" href="classviennacl_1_1ocl_1_1context.html#a9094ac71f0cdf80df698c0c84ebb483d">add_program</a>(my_prog, <span class="stringliteral">"my_compute_program"</span>);</div>
<div class="line"> <a class="code" href="classviennacl_1_1ocl_1_1kernel.html">viennacl::ocl::kernel</a> & my_vcl_kernel = my_vcl_prog.<a class="code" href="classviennacl_1_1ocl_1_1program.html#aa4f77fdcd02daa7d71627dc20117ba75">add_kernel</a>(my_kernel, <span class="stringliteral">"elementwise_prod"</span>);</div>
<div class="line"> <a class="code" href="namespaceviennacl_1_1ocl.html#a5f2022f653ea1cf364d20e3ff84dcada">viennacl::ocl::enqueue</a>(my_vcl_kernel(vcl_vec1, vcl_vec2, vcl_result, static_cast<cl_uint>(vcl_vec1.<a name="a20"></a><a class="code" href="classviennacl_1_1vector__base.html#a15c47ae4326098aeaa4ed6b91fc6df9b">size</a>()))); <span class="comment">//Note that std::size_t might differ between host and device. Thus, a cast to cl_uint is necessary here.</span></div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec1 : "</span>;</div>
<div class="line"> std::cout << vcl_vec1 << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"vec2 : "</span>;</div>
<div class="line"> std::cout << vcl_vec2 << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"result: "</span>;</div>
<div class="line"> std::cout << vcl_result << std::endl;</div>
<div class="line"></div>
<div class="line"></div>
<div class="line"> <a class="code" href="classviennacl_1_1matrix.html">viennacl::matrix<ScalarType></a> vcl_matrix(mem_vec1, 3, 3);</div>
<div class="line"></div>
<div class="line"> vcl_vec2.resize(3); <span class="comment">//note that the resize operation leads to new memory, thus vcl_vec2 is now at a different memory location (values are copied)</span></div>
<div class="line"> vcl_result.<a name="a21"></a><a class="code" href="classviennacl_1_1vector.html#a1b73aadf0c7b6c0028fd237ebb30c767">resize</a>(3); <span class="comment">//note that the resize operation leads to new memory, thus vcl_vec2 is now at a different memory location (values are copied)</span></div>
<div class="line"> vcl_result = <a class="code" href="namespaceviennacl_1_1linalg.html#aa18d10f8a90e38bd9ff43c650fc670ef">viennacl::linalg::prod</a>(vcl_matrix, vcl_vec2);</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"result of matrix-vector product: "</span>;</div>
<div class="line"> std::cout << vcl_result << std::endl;</div>
<div class="line"></div>
<div class="line"> std::cout << <span class="stringliteral">"!!!! TUTORIAL COMPLETED SUCCESSFULLY !!!!"</span> << std::endl;</div>
<div class="line"></div>
<div class="line"> <span class="keywordflow">return</span> EXIT_SUCCESS;</div>
<div class="line">}</div>
<div class="line"></div>
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