Sum_Array.cu

%%cu

#include<cuda_runtime_api.h>
#include<stdio.h>
#include<time.h>
#include<stdlib.h>
#include<cstring>


__global__ void sum_array_gpu(int * a, int * b, int * c, int size)
{
    int gid = blockIdx.x * blockDim.x + threadIdx.x;
    if(gid<size)
    {
        c[gid] = a[gid] + b[gid];
    }
}

void sum_array_cpu(int * a, int * b, int * c, int size)
{
    for(int i = 0 ; i<size; i++);
    {
        c[i] = a[i] +b[i];
    }
}

int main()
{
    int size 10000;
    int block_size = 128;

    int NO_BYTES = size * sizeof(int);

    //host pointers
    int * h_a, *h_b, *gpu_results, *h_c;

    //allocate memory for host pointers
    h_a = (int*)malloc(NO_BYTES);
    h_b = (int*)malloc(NO_BYTES);
    gpu_results = (int*)malloc(NO_BYTES);
    h_c = (int*)malloc(NO_BYTES);

    //initialize host pointer

    time_t t;
    srand((unsigned)time(&t));
    for(int i = 0; i < size; i++)
    {
        h_a[i] = (int)(rand() & 0xFF); 
    }

    for(int i = 0; i < size; i++)
    {
        h_b[i] = (int)(rand() & 0xFF); 
    }

    sum_array_cpu(h_a, h_b, h_c, size);



    memset(gpu_results,0,NO_BYTES);

    //device pointer
    int* d_a, *d_b, *d_c;
    cudaMalloc((int **)&d_a, NO_BYTES);
    cudaMalloc((int **)&d_b, NO_BYTES);
    cudaMalloc((int **)&d_c, NO_BYTES);

    cudaMemcpy(d_a,h_a,NO_BYTES,cudaMemcpyHostToDevice);
    cudaMemcpy(d_b,h_b,NO_BYTES,cudaMemcpyHostToDevice);
    cudaMemcpy(d_c,h_c,NO_BYTES,cudaMemcpyHostToDevice);

    //launching the grid
    dim3 block(block_size);
    dim3 grid((size/block.x) + 1);

    sum_array_gpu<<< grid, block >>>(d_a,d_b, d_c, size);
    cudaDeviceSynchronize();

    cudaMemcpy(gpu_results, d_c, NO_BYTES, cudaMemcpyDeviceToHost);

    //array comparison
    // compare_arrays(gpu_results,h_c,size);
    // void compare_arrays(int * a, float * b, float size)

	for (int i = 0; i < size; i++)
	{
		if (gpu_results[i] != h_c[i])
		{
			printf("Arrays are different \n");
			
			return;
		}
	}
	printf("Arrays are same \n");

    cudaFree(d_c);
    cudaFree(d_b);
    cudaFree(d_a);

    free(gpu_results);
    //free(h_c);
    free(h_a);
    free(h_b);

    cudaDeviceReset();
    return 0;
}

/tmp/tmpe8fmjutv/ca2dfea9-2a7d-45ec-929f-a157e8bda3de.cu(22): error: identifier "i" is undefined

/tmp/tmpe8fmjutv/ca2dfea9-2a7d-45ec-929f-a157e8bda3de.cu(28): error: expected a ";"

/tmp/tmpe8fmjutv/ca2dfea9-2a7d-45ec-929f-a157e8bda3de.cu(31): warning: variable "size" is used before its value is set

/tmp/tmpe8fmjutv/ca2dfea9-2a7d-45ec-929f-a157e8bda3de.cu(91): warning: non-void function "main" should return a value

2 errors detected in the compilation of "/tmp/tmpxft_00000115_00000000-8_ca2dfea9-2a7d-45ec-929f-a157e8bda3de.cpp1.ii".