Adapted from here: http:\/\/developer.amd.com\/GPU\/ATISTREAMSDK\/pages\/TutorialOpenCL.aspx<\/p>\n
But tidied up a little and made to work on MacOS. It creates a OpenCL executor “thing” and tells it to run a kernel which writes “Hello World” to a buffer, this gets sent back to the main C++ program.<\/p>\n
#include “cl.hpp” std::string prog( int main(void) { \/\/ Get list of platforms (things that can execute OpenCL on this host), get a “context” on the first executor. \/\/ Allocate 100 bytes of memory which we will use to communicate with the OpenCL context, executor, whatever. \/\/ Give the OpenCL program embedded in the string above to OpenCL. \/\/ Get devices used in this “context” \/\/ Compile program against device \/\/ create a kernel object, tell it we are using the kernel called “hello”, give it an argument which is the memory we alloc’d above. \/\/ Queue the kernel up to run \/\/ Use the event object above to block until processing has completed \/\/ Read the results out of the shared memory area. \/\/ Write to screen Adapted from here: http:\/\/developer.amd.com\/GPU\/ATISTREAMSDK\/pages\/TutorialOpenCL.aspx But tidied up a little and made to work on MacOS. It creates a OpenCL executor “thing” and tells it to run a kernel which writes “Hello World” to a buffer, this gets sent back to the main C++ program. #include “cl.hpp” #include #include std::string prog( “#pragma OPENCL EXTENSION cl_khr_byte_addressable_store : […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1],"tags":[],"class_list":["post-218","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1RRoU-3w","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/218","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/comments?post=218"}],"version-history":[{"count":4,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/218\/revisions"}],"predecessor-version":[{"id":229,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/218\/revisions\/229"}],"wp:attachment":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/media?parent=218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/categories?post=218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/tags?post=218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n#include
\n#include
\n“#pragma OPENCL EXTENSION cl_khr_byte_addressable_store : enable\\n” \\
\n“__constant char hw[] = \\”Hello World\\”; \\n” \\
\n“__kernel void hello(__global char * out) {\\n” \\
\n” size_t tid = get_global_id(0); \\n” \\
\n” out[tid] = hw[tid]; \\n” \\
\n“}\\n”);<\/p>\n
\n cl_int err;<\/p>\n
\n std::vector
\n cl::Platform::get(&amp;platformList);
\n cl_context_properties cprops[3] = {CL_CONTEXT_PLATFORM, (cl_context_properties)(platformList[0])(), 0};
\n cl::Context context( CL_DEVICE_TYPE_CPU, cprops, NULL, NULL, &amp;err);<\/p>\n
\n size_t mem_size = 100;
\n char * outH = new char[mem_size];
\n cl::Buffer outCL( context, CL_MEM_WRITE_ONLY | CL_MEM_USE_HOST_PTR, mem_size, outH, &amp;err);<\/p>\n
\n cl::Program::Sources source(1, std::make_pair(prog.c_str(), prog.length()+1));<\/p>\n
\n std::vector
\n devices = context.getInfo
\n cl::Program program(context, source);
\n err = program.build(devices,””);<\/p>\n
\n cl::Kernel kernel(program, “hello”, &amp;err);
\n err = kernel.setArg(0, outCL);<\/p>\n
\n cl::CommandQueue queue(context, devices[0], 0, &amp;err);
\n cl::Event event;
\n err = queue.enqueueNDRangeKernel( kernel, cl::NullRange, cl::NDRange(mem_size), cl::NDRange(1, 1), NULL, &amp;event);<\/p>\n
\n event.wait();<\/p>\n
\n err = queue.enqueueReadBuffer( outCL, CL_TRUE, 0, mem_size, outH);<\/p>\n
\n std::cout << outH;\n}\n[\/sourcecode]\n\nOn MacOS compile it with: g++ .\/simple.cpp -framework OpenCL -o simple\n\nYou'll also need to C++ bindings for OpenCL which are available here: http:\/\/www.khronos.org\/registry\/cl\/api\/1.0\/cl.hpp\n\nTarball containing all this is HERE<\/a> untar it and type make to build.<\/p>\n","protected":false},"excerpt":{"rendered":"