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@redroc redroc/HelloWorld.cl
Last active Jan 11, 2019

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opencl_HelloWorld
__kernel void hello_kernel(__global const float *a,
__global const float *b,
__global float *result)
{
int gid = get_global_id(0);
result[gid] = a[gid] + b[gid];
}
//
// Book: OpenCL(R) Programming Guide
// Authors: Aaftab Munshi, Benedict Gaster, Timothy Mattson, James Fung, Dan Ginsburg
// ISBN-10: 0-321-74964-2
// ISBN-13: 978-0-321-74964-2
// Publisher: Addison-Wesley Professional
// URLs: http://safari.informit.com/9780132488006/
// http://www.openclprogrammingguide.com
//
// HelloWorld.cpp
//
// This is a simple example that demonstrates basic OpenCL setup and
// use.
#include <iostream>
#include <fstream>
#include <sstream>
#ifdef __APPLE__
#include <OpenCL/cl.h>
#else
#include <CL/cl.h>
#endif
///
// Constants
//
const int ARRAY_SIZE = 1000;
///
// Create an OpenCL context on the first available platform using
// either a GPU or CPU depending on what is available.
//
cl_context CreateContext()
{
cl_int errNum;
cl_uint numPlatforms;
cl_platform_id firstPlatformId;
cl_context context = NULL;
// First, select an OpenCL platform to run on. For this example, we
// simply choose the first available platform. Normally, you would
// query for all available platforms and select the most appropriate one.
errNum = clGetPlatformIDs(1, &firstPlatformId, &numPlatforms);
if (errNum != CL_SUCCESS || numPlatforms <= 0)
{
std::cerr << "Failed to find any OpenCL platforms." << std::endl;
return NULL;
}
// Next, create an OpenCL context on the platform. Attempt to
// create a GPU-based context, and if that fails, try to create
// a CPU-based context.
cl_context_properties contextProperties[] =
{
CL_CONTEXT_PLATFORM,
(cl_context_properties)firstPlatformId,
0
};
context = clCreateContextFromType(contextProperties, CL_DEVICE_TYPE_GPU,
NULL, NULL, &errNum);
if (errNum != CL_SUCCESS)
{
std::cout << "Could not create GPU context, trying CPU..." << std::endl;
context = clCreateContextFromType(contextProperties, CL_DEVICE_TYPE_CPU,
NULL, NULL, &errNum);
if (errNum != CL_SUCCESS)
{
std::cerr << "Failed to create an OpenCL GPU or CPU context." << std::endl;
return NULL;
}
}
return context;
}
///
// Create a command queue on the first device available on the
// context
//
cl_command_queue CreateCommandQueue(cl_context context, cl_device_id *device)
{
cl_int errNum;
cl_device_id *devices;
cl_command_queue commandQueue = NULL;
size_t deviceBufferSize = -1;
// First get the size of the devices buffer
errNum = clGetContextInfo(context, CL_CONTEXT_DEVICES, 0, NULL, &deviceBufferSize);
if (errNum != CL_SUCCESS)
{
std::cerr << "Failed call to clGetContextInfo(...,GL_CONTEXT_DEVICES,...)";
return NULL;
}
if (deviceBufferSize <= 0)
{
std::cerr << "No devices available.";
return NULL;
}
// Allocate memory for the devices buffer
devices = new cl_device_id[deviceBufferSize / sizeof(cl_device_id)];
errNum = clGetContextInfo(context, CL_CONTEXT_DEVICES, deviceBufferSize, devices, NULL);
if (errNum != CL_SUCCESS)
{
delete [] devices;
std::cerr << "Failed to get device IDs";
return NULL;
}
// In this example, we just choose the first available device. In a
// real program, you would likely use all available devices or choose
// the highest performance device based on OpenCL device queries
commandQueue = clCreateCommandQueue(context, devices[0], 0, NULL);
if (commandQueue == NULL)
{
delete [] devices;
std::cerr << "Failed to create commandQueue for device 0";
return NULL;
}
*device = devices[0];
delete [] devices;
return commandQueue;
}
///
// Create an OpenCL program from the kernel binary file
//
cl_program CreateProgramWithBinary(cl_context context, cl_device_id device, const char* fileName)
{
FILE *fp = fopen(fileName, "rb");
if (fp == NULL)
{
return NULL;
}
// Determine the size of the binary
size_t binarySize;
fseek(fp, 0, SEEK_END);
binarySize = ftell(fp);
rewind(fp);
// Load binary from disk
unsigned char *programBinary = new unsigned char[binarySize];
fread(programBinary, 1, binarySize, fp);
fclose(fp);
cl_int errNum = 0;
cl_program program;
cl_int binaryStatus;
program = clCreateProgramWithBinary(context,
1,
&device,
&binarySize,
(const unsigned char**)&programBinary,
&binaryStatus,
&errNum);
delete [] programBinary;
if (errNum != CL_SUCCESS)
{
std::cerr << "Error loading program binary." << std::endl;
return NULL;
}
if (binaryStatus != CL_SUCCESS)
{
std::cerr << "Invalid binary for device" << std::endl;
return NULL;
}
errNum = clBuildProgram(program, 0, NULL, NULL, NULL, NULL);
if (errNum != CL_SUCCESS)
{
// Determine the reason for the error
char buildLog[16384];
clGetProgramBuildInfo(program, device, CL_PROGRAM_BUILD_LOG,
sizeof(buildLog), buildLog, NULL);
std::cerr << "Error in program: " << std::endl;
std::cerr << buildLog << std::endl;
clReleaseProgram(program);
return NULL;
}
return program;
}
///
// Create an OpenCL program from the kernel source file
//
cl_program CreateProgram(cl_context context, cl_device_id device, const char* fileName)
{
cl_int errNum;
cl_program program;
std::ifstream kernelFile(fileName, std::ios::in);
if (!kernelFile.is_open())
{
std::cerr << "Failed to open file for reading: " << fileName << std::endl;
return NULL;
}
std::ostringstream oss;
oss << kernelFile.rdbuf();
std::string srcStdStr = oss.str();
const char *srcStr = srcStdStr.c_str();
program = clCreateProgramWithSource(context, 1,
(const char**)&srcStr,
NULL, NULL);
if (program == NULL)
{
std::cerr << "Failed to create CL program from source." << std::endl;
return NULL;
}
errNum = clBuildProgram(program, 0, NULL, NULL, NULL, NULL);
if (errNum != CL_SUCCESS)
{
// Determine the reason for the error
char buildLog[16384];
clGetProgramBuildInfo(program, device, CL_PROGRAM_BUILD_LOG,
sizeof(buildLog), buildLog, NULL);
std::cerr << "Error in kernel: " << std::endl;
std::cerr << buildLog;
clReleaseProgram(program);
return NULL;
}
return program;
}
///
// Create memory objects used as the arguments to the kernel
// The kernel takes three arguments: result (output), a (input),
// and b (input)
//
bool CreateMemObjects(cl_context context, cl_mem memObjects[3],
float *a, float *b)
{
memObjects[0] = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
sizeof(float) * ARRAY_SIZE, a, NULL);
memObjects[1] = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR,
sizeof(float) * ARRAY_SIZE, b, NULL);
memObjects[2] = clCreateBuffer(context, CL_MEM_READ_WRITE,
sizeof(float) * ARRAY_SIZE, NULL, NULL);
if (memObjects[0] == NULL || memObjects[1] == NULL || memObjects[2] == NULL)
{
std::cerr << "Error creating memory objects." << std::endl;
return false;
}
return true;
}
///
// Cleanup any created OpenCL resources
//
void Cleanup(cl_context context, cl_command_queue commandQueue,
cl_program program, cl_kernel kernel, cl_mem memObjects[3])
{
for (int i = 0; i < 3; i++)
{
if (memObjects[i] != 0)
clReleaseMemObject(memObjects[i]);
}
if (commandQueue != 0)
clReleaseCommandQueue(commandQueue);
if (kernel != 0)
clReleaseKernel(kernel);
if (program != 0)
clReleaseProgram(program);
if (context != 0)
clReleaseContext(context);
}
///
// main() for HelloWorld example
//
int main(int argc, char** argv)
{
cl_context context = 0;
cl_command_queue commandQueue = 0;
cl_program program = 0;
cl_device_id device = 0;
cl_kernel kernel = 0;
cl_mem memObjects[3] = { 0, 0, 0 };
cl_int errNum;
// Create an OpenCL context on first available platform
context = CreateContext();
if (context == NULL)
{
std::cerr << "Failed to create OpenCL context." << std::endl;
return 1;
}
// Create a command-queue on the first device available
// on the created context
commandQueue = CreateCommandQueue(context, &device);
if (commandQueue == NULL)
{
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
// Create OpenCL program from HelloWorld.cl kernel source
program = CreateProgram(context, device, "HelloWorld.cl");
if (program == NULL)
{
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
// Create OpenCL kernel
kernel = clCreateKernel(program, "hello_kernel", NULL);
if (kernel == NULL)
{
std::cerr << "Failed to create kernel" << std::endl;
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
// Create memory objects that will be used as arguments to
// kernel. First create host memory arrays that will be
// used to store the arguments to the kernel
float result[ARRAY_SIZE];
float a[ARRAY_SIZE];
float b[ARRAY_SIZE];
for (int i = 0; i < ARRAY_SIZE; i++)
{
a[i] = (float)i;
b[i] = (float)(i * 2);
}
if (!CreateMemObjects(context, memObjects, a, b))
{
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
// Set the kernel arguments (result, a, b)
errNum = clSetKernelArg(kernel, 0, sizeof(cl_mem), &memObjects[0]);
errNum |= clSetKernelArg(kernel, 1, sizeof(cl_mem), &memObjects[1]);
errNum |= clSetKernelArg(kernel, 2, sizeof(cl_mem), &memObjects[2]);
if (errNum != CL_SUCCESS)
{
std::cerr << "Error setting kernel arguments." << std::endl;
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
size_t globalWorkSize[1] = { ARRAY_SIZE };
size_t localWorkSize[1] = { 1 };
// Queue the kernel up for execution across the array
errNum = clEnqueueNDRangeKernel(commandQueue, kernel, 1, NULL,
globalWorkSize, localWorkSize,
0, NULL, NULL);
if (errNum != CL_SUCCESS)
{
std::cerr << "Error queuing kernel for execution." << std::endl;
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
// Read the output buffer back to the Host
errNum = clEnqueueReadBuffer(commandQueue, memObjects[2], CL_TRUE,
0, ARRAY_SIZE * sizeof(float), result,
0, NULL, NULL);
if (errNum != CL_SUCCESS)
{
std::cerr << "Error reading result buffer." << std::endl;
Cleanup(context, commandQueue, program, kernel, memObjects);
return 1;
}
// Output the result buffer
for (int i = 0; i < ARRAY_SIZE; i++)
{
std::cout << result[i] << " ";
}
std::cout << std::endl;
std::cout << "Executed program succesfully." << std::endl;
Cleanup(context, commandQueue, program, kernel, memObjects);
return 0;
}
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