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- //
- // File: hello.c
- //
- // Abstract: A simple "Hello World" compute example showing basic usage of OpenCL which
- // calculates the mathematical square (X[i] = pow(X[i],2)) for a buffer of
- // floating point values.
- //
- //
- // Version: <1.0>
- //
- // Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple Inc. ("Apple")
- // in consideration of your agreement to the following terms, and your use,
- // installation, modification or redistribution of this Apple software
- // constitutes acceptance of these terms. If you do not agree with these
- // terms, please do not use, install, modify or redistribute this Apple
- // software.
- //
- // In consideration of your agreement to abide by the following terms, and
- // subject to these terms, Apple grants you a personal, non - exclusive
- // license, under Apple's copyrights in this original Apple software ( the
- // "Apple Software" ), to use, reproduce, modify and redistribute the Apple
- // Software, with or without modifications, in source and / or binary forms;
- // provided that if you redistribute the Apple Software in its entirety and
- // without modifications, you must retain this notice and the following text
- // and disclaimers in all such redistributions of the Apple Software. Neither
- // the name, trademarks, service marks or logos of Apple Inc. may be used to
- // endorse or promote products derived from the Apple Software without specific
- // prior written permission from Apple. Except as expressly stated in this
- // notice, no other rights or licenses, express or implied, are granted by
- // Apple herein, including but not limited to any patent rights that may be
- // infringed by your derivative works or by other works in which the Apple
- // Software may be incorporated.
- //
- // The Apple Software is provided by Apple on an "AS IS" basis. APPLE MAKES NO
- // WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
- // WARRANTIES OF NON - INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A
- // PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND OPERATION
- // ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
- //
- // IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR
- // CONSEQUENTIAL DAMAGES ( INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- // INTERRUPTION ) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION, MODIFICATION
- // AND / OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED AND WHETHER
- // UNDER THEORY OF CONTRACT, TORT ( INCLUDING NEGLIGENCE ), STRICT LIABILITY OR
- // OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- //
- // Copyright ( C ) 2008 Apple Inc. All Rights Reserved.
- //
- ////////////////////////////////////////////////////////////////////////////////
- #include <fcntl.h>
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <math.h>
- #include <unistd.h>
- #include <sys/types.h>
- #include <sys/stat.h>
- #include <CL/cl.h>
- ////////////////////////////////////////////////////////////////////////////////
- // Use a static data size for simplicity
- //
- #define DATA_SIZE (65536)
- ////////////////////////////////////////////////////////////////////////////////
- // Simple compute kernel which computes the square of an input array
- //
- const char *KernelSource = "\n" \
- "__kernel void square( \n" \
- " __global float* input, \n" \
- " __global float* output, \n" \
- " const unsigned int count) \n" \
- "{ \n" \
- " int i = get_global_id(0); \n" \
- " if(i < count) \n" \
- " output[i] = input[i] * input[i]; \n" \
- "} \n" \
- "\n";
- ////////////////////////////////////////////////////////////////////////////////
- int main(int argc, char** argv)
- {
- int err; // error code returned from api calls
- float data[DATA_SIZE]; // original data set given to device
- float results[DATA_SIZE]; // results returned from device
- unsigned int correct; // number of correct results returned
- size_t global; // global domain size for our calculation
- size_t local; // local domain size for our calculation
- cl_platform_id platform;
- cl_device_id device_id; // compute device id
- cl_context context; // compute context
- cl_command_queue commands; // compute command queue
- cl_program program; // compute program
- cl_kernel kernel; // compute kernel
- cl_mem input; // device memory used for the input array
- cl_mem output; // device memory used for the output array
- // Fill our data set with random float values
- //
- int i = 0;
- unsigned int count = DATA_SIZE;
- for(i = 0; i < count; i++)
- data[i] = rand() / (float)RAND_MAX;
- // Get Platform IDs
- err = clGetPlatformIDs(1, &platform, NULL);
- if (err != CL_SUCCESS) {
- printf("Error: Failed to query platforms! (%d)\n", err);
- return EXIT_FAILURE;
- }
- // Connect to a compute device
- //
- int gpu = 1;
- err = clGetDeviceIDs(platform, gpu ? CL_DEVICE_TYPE_GPU : CL_DEVICE_TYPE_CPU, 1, &device_id, NULL);
- if (err != CL_SUCCESS)
- {
- printf("Error: Failed to create a device group! (%d)\n", err);
- return EXIT_FAILURE;
- }
- // Create a compute context
- //
- context = clCreateContext(0, 1, &device_id, NULL, NULL, &err);
- if (!context)
- {
- printf("Error: Failed to create a compute context! (%d)\n", err);
- return EXIT_FAILURE;
- }
- // Create a command commands
- //
- commands = clCreateCommandQueue(context, device_id, 0, &err);
- if (!commands)
- {
- printf("Error: Failed to create a command commands!\n");
- return EXIT_FAILURE;
- }
- // Create the compute program from the source buffer
- //
- program = clCreateProgramWithSource(context, 1, (const char **) & KernelSource, NULL, &err);
- if (!program)
- {
- printf("Error: Failed to create compute program!\n");
- return EXIT_FAILURE;
- }
- // Build the program executable
- //
- err = clBuildProgram(program, 0, NULL, NULL, NULL, NULL);
- if (err != CL_SUCCESS)
- {
- size_t len;
- char buffer[2048];
- printf("Error: Failed to build program executable!\n");
- clGetProgramBuildInfo(program, device_id, CL_PROGRAM_BUILD_LOG, sizeof(buffer), buffer, &len);
- printf("%s\n", buffer);
- exit(1);
- }
- // Create the compute kernel in the program we wish to run
- //
- kernel = clCreateKernel(program, "square", &err);
- if (!kernel || err != CL_SUCCESS)
- {
- printf("Error: Failed to create compute kernel!\n");
- exit(1);
- }
- // Create the input and output arrays in device memory for our calculation
- //
- input = clCreateBuffer(context, CL_MEM_READ_ONLY, sizeof(float) * count, NULL, NULL);
- output = clCreateBuffer(context, CL_MEM_WRITE_ONLY, sizeof(float) * count, NULL, NULL);
- if (!input || !output)
- {
- printf("Error: Failed to allocate device memory!\n");
- exit(1);
- }
- // Write our data set into the input array in device memory
- //
- err = clEnqueueWriteBuffer(commands, input, CL_TRUE, 0, sizeof(float) * count, data, 0, NULL, NULL);
- if (err != CL_SUCCESS)
- {
- printf("Error: Failed to write to source array!\n");
- exit(1);
- }
- // Set the arguments to our compute kernel
- //
- err = 0;
- err = clSetKernelArg(kernel, 0, sizeof(cl_mem), &input);
- err |= clSetKernelArg(kernel, 1, sizeof(cl_mem), &output);
- err |= clSetKernelArg(kernel, 2, sizeof(unsigned int), &count);
- if (err != CL_SUCCESS)
- {
- printf("Error: Failed to set kernel arguments! %d\n", err);
- exit(1);
- }
- // Get the maximum work group size for executing the kernel on the device
- //
- err = clGetKernelWorkGroupInfo(kernel, device_id, CL_KERNEL_WORK_GROUP_SIZE, sizeof(local), &local, NULL);
- if (err != CL_SUCCESS)
- {
- printf("Error: Failed to retrieve kernel work group info! %d\n", err);
- exit(1);
- }
- // Execute the kernel over the entire range of our 1d input data set
- // using the maximum number of work group items for this device
- //
- global = count;
- err = clEnqueueNDRangeKernel(commands, kernel, 1, NULL, &global, &local, 0, NULL, NULL);
- if (err)
- {
- printf("Error: Failed to execute kernel!\n");
- return EXIT_FAILURE;
- }
- // Wait for the command commands to get serviced before reading back results
- //
- clFinish(commands);
- // Read back the results from the device to verify the output
- //
- err = clEnqueueReadBuffer( commands, output, CL_TRUE, 0, sizeof(float) * count, results, 0, NULL, NULL );
- if (err != CL_SUCCESS)
- {
- printf("Error: Failed to read output array! %d\n", err);
- exit(1);
- }
- // Validate our results
- //
- correct = 0;
- for(i = 0; i < count; i++)
- {
- if(results[i] == data[i] * data[i])
- correct++;
- }
- // Print a brief summary detailing the results
- //
- printf("Computed '%d/%d' correct values!\n", correct, count);
- // Shutdown and cleanup
- //
- clReleaseMemObject(input);
- clReleaseMemObject(output);
- clReleaseProgram(program);
- clReleaseKernel(kernel);
- clReleaseCommandQueue(commands);
- clReleaseContext(context);
- return 0;
- }
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