Add Collatz Conjecture tester

Makefile

@@ -1,2 +1,7 @@
+.PHONY: hello collatz
+
+collatz: collatz.cpp
+	clang++ -o collatz collatz.cpp -lOpenCL
+
 hello: main.cpp
 	g++ -o hello main.cpp -lOpenCL

collatz-kernel.cl

@@ -0,0 +1,21 @@
+#pragma OPENCL EXTENSION cl_khr_byte_addressable_store : enable
+
+__kernel void collatz(__global unsigned int* inputNums,
+							 __global unsigned int* triesArr) {
+  int N = get_global_id(1) * get_global_size(0) + get_global_id(0);
+  int val = N + 1;
+  int tries = 0;
+
+  inputNums[N] = val;
+  
+  while(val != 1) {
+	 if(val % 2 == 0) {
+		val = val / 2;
+	 } else {
+		val = 3 * val + 1;
+	 }
+	 tries++;
+  }
+
+  triesArr[N] = tries;
+}

collatz.cpp

@@ -0,0 +1,101 @@
+#define CL_TARGET_OPENCL_VERSION 120
+
+#include <utility>
+#include <CL/cl.hpp>
+#include <cstdio>
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <string>
+#include <iterator>
+
+const std::string hw("Hello World!");
+
+inline void checkErr(cl_int err, const char* name) {
+	if(err != CL_SUCCESS) {
+		std::cerr << "ERROR: " << name << " (" << err << ")" << std::endl;
+		exit(EXIT_FAILURE);
+	}
+}
+
+void initMatrix(float *mat, int size) {
+	for(int i = 0; i < size; i++) {
+		mat[i] = rand() % 50;
+	}
+}
+
+int main(void) {
+	cl_int err;
+
+	std::vector<cl::Platform> platformList;
+	cl::Platform::get(&platformList);
+	checkErr(platformList.size() != 0 ? CL_SUCCESS : -1, "cl::Platform::get");
+
+	std::cerr << "Number of platforms: " << platformList.size() << std::endl;
+
+	for(int i = 0; i < platformList.size(); i++) {
+      std::string platformVendor;
+   	platformList[i].getInfo((cl_platform_info)CL_PLATFORM_VENDOR, &platformVendor);
+   	std::cerr << "Platform #" << i << " Vendor: " << platformVendor << std::endl;
+      std::string platformName;
+      platformList[i].getInfo((cl_platform_info)CL_PLATFORM_NAME, &platformName);
+      std::cerr << "Platform #" << i << " Name: " << platformName << std::endl;
+   }
+
+	cl_context_properties cprops[3] = { CL_CONTEXT_PLATFORM, (cl_context_properties)(platformList[0])(), 0 };
+	cl::Context context(CL_DEVICE_TYPE_GPU, cprops, NULL, NULL, &err);
+	checkErr(err, "Context::Context()");
+
+	// Matrices as seen on OpenCL device
+	cl::Buffer inputNums_device;
+	cl::Buffer tries_device;
+
+	// Host side allocations
+	const unsigned int NUM_ITEMS = 1024*1024;
+
+	size_t arrSize = NUM_ITEMS * sizeof(int);
+
+	unsigned int *inputNums_host = (unsigned int*)malloc(arrSize);
+	unsigned int *tries_host = (unsigned int*)malloc(arrSize);
+	
+	std::vector<cl::Device> devices;
+	devices = context.getInfo<CL_CONTEXT_DEVICES>();
+	checkErr(devices.size() > 0 ? CL_SUCCESS : -1, "devices.size() > 0");
+
+	std::ifstream file("collatz-kernel.cl");
+	checkErr(file.is_open() ? CL_SUCCESS : -1, "collatz-kernel.cl");
+
+	std::string programSourceString(std::istreambuf_iterator<char>(file), (std::istreambuf_iterator<char>()));
+	cl::Program::Sources programSource(1, std::make_pair(programSourceString.c_str(), programSourceString.length() + 1));
+	cl::Program program(context, programSource);
+	err = program.build(devices, "");
+	checkErr(err, "Program::Build()");
+
+	cl::Kernel kernel(program, "collatz", &err);
+	checkErr(err, "Kernel::Kernel()");
+
+	inputNums_device = cl::Buffer(context, CL_MEM_WRITE_ONLY, arrSize, NULL, &err);
+	tries_device = cl::Buffer(context, CL_MEM_WRITE_ONLY, arrSize, NULL, &err);
+	
+	size_t localWorkSize[2], globalWorkSize[2];
+
+	err = kernel.setArg(0, inputNums_device);
+	err = kernel.setArg(1, tries_device);
+	localWorkSize[0] = 16;
+	localWorkSize[1] = 16;
+	globalWorkSize[0] = 1024;
+	globalWorkSize[1] = 1024;
+
+	cl::CommandQueue queue(context, devices[0], 0, &err);
+	checkErr(err, "CommandQueue::CommandQueue()");
+	cl::Event event;
+	err = queue.enqueueNDRangeKernel(kernel, cl::NullRange, cl::NDRange(1024, 1024), cl::NDRange(16, 16), NULL, &event);
+	checkErr(err, "CommandQueue::enqueueNDRangeKernel()");
+
+	event.wait();
+	err = queue.enqueueReadBuffer(tries_device, CL_TRUE, 0, arrSize, tries_host);
+	err = queue.enqueueReadBuffer(inputNums_device, CL_TRUE, 0, arrSize, inputNums_host);
+	checkErr(err, "CommandQueue::enqueueReadBuffer()");
+
+	return EXIT_SUCCESS;
+}