CUDA实例练习（六）：矢量求和

#include <stdio.h>
#include <cuda_runtime.h>
#include <device_launch_parameters.h>
#include <book.h>
#include <gputimer.h>
#define N (33 * 1024)

__global__ void add(int *a, int *b, int *c){
    int tid = threadIdx.x + blockIdx.x * blockDim.x;
    while (tid < N){
        c[tid] = a[tid] + b[tid];
        tid += blockDim.x * gridDim.x;
    }
}

int main(void){
    int a[N], b[N], c[N];
    int *dev_a, *dev_b, *dev_c;

    HANDLE_ERROR(cudaMalloc((void **)&dev_a, N * sizeof(int)));
    HANDLE_ERROR(cudaMalloc((void **)&dev_b, N*sizeof(int)));
    HANDLE_ERROR(cudaMalloc((void **)&dev_c, N*sizeof(int)));

    for (int i = 0; i < N; i++){
        a[i] = i;
        b[i] = i*i;
    }

    HANDLE_ERROR(cudaMemcpy(dev_a, a, N*sizeof(int), cudaMemcpyHostToDevice));
    HANDLE_ERROR(cudaMemcpy(dev_b, b, N*sizeof(int), cudaMemcpyHostToDevice));
    add << <128, 128 >> >(dev_a, dev_b, dev_c);
    
    HANDLE_ERROR(cudaMemcpy(c, dev_c, N*sizeof(int), cudaMemcpyDeviceToHost));

    bool success = true;
    for (int i = 0; i < N; i++){
        if (a[i] + b[i] != c[i]){
            printf("Error: %d + %d != %d
", a[i], b[i], c[i]);
            success = false;
        }
    }
    if (success)
        printf("We did it!
");

    cudaFree(dev_a);
    cudaFree(dev_b);
    cudaFree(dev_c);
    return 0;
}