Hello!
I am just a beginner with OpenCL and I try to implement Buffons needle experiment and get number PI.
here is my code:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include <CL/cl.h>
#define MAX_SOURCE_SIZE (0x100000)
int main(void) {
srand((unsigned)time(NULL));
const int LIST_SIZE = 1024;
int i;
// Load the kernel source code into the array source_str
FILE *fp;
char *source_str;
size_t source_size;
fp = fopen("./kernelagain.cl", "r");
if (!fp) {
fprintf(stderr, "Failed to load kernel.
");
exit(1);
}
source_str = (char*)malloc(MAX_SOURCE_SIZE);
source_size = fread( source_str, 1, MAX_SOURCE_SIZE, fp);
fclose( fp );
// Get platform and device information
cl_platform_id platform_id = NULL;
cl_device_id device_id = NULL;
cl_uint ret_num_devices;
cl_uint ret_num_platforms;
cl_int ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);
ret = clGetDeviceIDs( platform_id, CL_DEVICE_TYPE_GPU, 1,
&device_id, &ret_num_devices);
// Create an OpenCL context
cl_context context = clCreateContext( NULL, 1, &device_id, NULL, NULL, &ret);
// Create a command queue
cl_command_queue command_queue = clCreateCommandQueue(context, device_id, 0, &ret);
// Create memory buffers on the device for each vector
cl_mem mem_result = clCreateBuffer(context, CL_MEM_WRITE_ONLY,
LIST_SIZE * sizeof(int), NULL, &ret);
// Create a program from the kernel source
cl_program program = clCreateProgramWithSource(context, 1,
(const char **)&source_str, (const size_t *)&source_size, &ret);
// Build the program
ret = clBuildProgram(program, 1, &device_id, NULL, NULL, NULL);
// Create the OpenCL kernel
cl_kernel kernel = clCreateKernel(program, "needle", &ret);
// Set the arguments of the kernel
ret = clSetKernelArg(kernel, 0, sizeof(cl_mem), (void *)&mem_result);
// Execute the OpenCL kernel on the list
size_t global_item_size = LIST_SIZE; // Process the entire lists
size_t local_item_size = 64; // Divide work items into groups of 64
ret = clEnqueueNDRangeKernel(command_queue, kernel, 1, NULL,
&global_item_size, &local_item_size, 0, NULL, NULL);
// Read the memory buffer C on the device to the local variable C
int *result = (int*)malloc(sizeof(int)*LIST_SIZE);
ret = clEnqueueReadBuffer(command_queue, mem_result, CL_TRUE, 0,
LIST_SIZE * sizeof(int), result, 0, NULL, NULL);
// Display the result to the screen
for(i = 0; i < LIST_SIZE; i++)
{printf("%d
", result[i]);}
// Clean up
ret = clFlush(command_queue);
ret = clFinish(command_queue);
ret = clReleaseKernel(kernel);
ret = clReleaseProgram(program);
ret = clReleaseMemObject(mem_result);
ret = clReleaseCommandQueue(command_queue);
ret = clReleaseContext(context);
free(result);
return 0;
}
and second part is:
__kernel void needle(__global int *out) {
int i = get_global_id(0);
const double PI = 3.14159265358979323846;
srand((unsigned)time(NULL));
double d=5; //size between lines
double l=2; //size of needle
double angle;
double position;
double f = (double)rand() / RAND_MAX;
double number = f * (2*PI);
angle = number;
f = (double)rand() / RAND_MAX;
number = f * (d);
position = number;
if( ( ( position + l*sin(angle)/2 >= d ) && ( position - l*sin(angle)/2 <= d ) ) ||
( ( position + l*sin(angle)/2 >= 0 ) && ( position - l*sin(angle)/2 <= 0 ) ) )
{
out[i]=1;
}
else out[i] = 0;
}
So can someone tell me why array “result” has values 0,1,2,3 … 1023 when I think it should be only 0 or 1.
Please help me cause I have no idea where is problem and sorry for my english