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Thread: Help: Adding two arrays

  1. #1

    Help: Adding two arrays

    I'm trying to write my first program, that adds two arrays, but it's not working. It's giving error on func.wait() saying "Access violation reading location 0x00000000" and I don't know why. What am I doing wrong?
    Code :
    #define __NO_STD_VECTOR
    #define __NO_STD_STRING
    #include <malloc.h>
    #include <cl.hpp>
    #include <iostream>
    using namespace std;
    using namespace cl;
    const char *kernelSrc =	"__kernel void"
    						"vectorAdd(__global const int *a,"
    						"__global const int *b,"
    						"__global int *resultado)"						
    						"// Vector element index"
    						"int nIndex = get_global_id(0);"
    						"resultado[nIndex] = a[nIndex] + b[nIndex];"
    int main(void)
    	const int size = 4;
    	// get platform
    	vector<Platform> platformList;
    	cout << "Platform number is: " << platformList.size() << endl;
    	// show platform info
    	cl::string platformInfo;
    	platformList[0].getInfo(CL_PLATFORM_VERSION, &platformInfo);
    	cout << "Platform Info: " << platformInfo.c_str() << endl;
    	// get available devices
    	vector<Device> devices;
    	platformList[0].getDevices(CL_DEVICE_TYPE_GPU, &devices);
    	cout << devices.size() << " device(s) found!" << endl;
    	// show device info
    	cl::string name;
    	devices[0].getInfo(CL_DEVICE_NAME, &name);
    	cout << "Device name: " << name.c_str() << endl;
    	// create OpenCL context
    	Context hContext(devices, 0, NULL, NULL, NULL);
    	// queue
    	CommandQueue queue(hContext, devices[0], 0, 0);
    	// Load source
    	cl::Program::Sources source(1, std::make_pair(kernelSrc,strlen(kernelSrc)));   
    	// create and build program
    	Program program(hContext, source, NULL);, NULL, NULL, NULL);
    	// Get the kernel so we can use it
    	Kernel kernel(program, "vectorAdd", NULL);
    	// arrays on host
    	int *a = new int[size];
    	int *b = new int[size];
    	int *c = new int[size];
    	// initialize
    	a[0]=1; a[1]=2; a[2]=20; a[3]=8;
    	b[0]=29; a[1]=28; a[2]=10; a[3]=22;
    	// result should be {30, 30, 30, 30}
    	// Allocate memory on device and copy the arrays there
    	Buffer bufferA(hContext, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, sizeof(int) * size, a, NULL);
    	Buffer bufferB(hContext, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, sizeof(int) * size, b, NULL);
    	// Create buffer to get output on kernel	
    	Buffer bufferResultado(hContext, CL_MEM_WRITE_ONLY, sizeof(int)*size, NULL, NULL);
    	// set arguments
    	kernel.setArg(0, bufferA);
    	kernel.setArg(1, bufferB);
    	kernel.setArg(2, bufferResultado);
    	// execute kernel
    	NDRange global(size);
    	NDRange local(2);
    	KernelFunctor func = kernel.bind(queue, global, local);	
    	func().wait(); // error here.................................................................................................
    	cout << "Done!" << endl;
    	// copy from device to host
    	queue.enqueueReadBuffer(bufferResultado, CL_TRUE, 0, sizeof(int)*size,  c, NULL, NULL);
    	for(int i=0; i<size; i++)
    		cout << c[i] << endl;	
    	return EXIT_SUCCESS;

  2. #2
    Junior Member
    Join Date
    Mar 2010

    Re: Help: Adding two arrays

    I am not sure whether I am answering you correctly or not since I am a newbie myself but the only thing which I didn't understand was that why have you made the local(2) just before you execute the kernel. You seem to have 4 elements and your global work size is 4 so why is the local work size (2). Might be changing that to 0 could solve your problem. This is just a thought...

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