CUDA编程学习（一）

/****c code****/ #include<stdio.h>



int main() { printf("Hello world!\n);

    return 0; } /****CUDA code****/ _global_ void mykernel(void) { } int main() { mykernel<<<1,1>>>(); printf("Hello world!\n"); return 0; }

 1: _global_ 这个符号代表这个函数是在GPU里面跑的

 2: mykernel<<<1,1>>>() Also called a "kernel launch" 

 

/**** Add two integers****/ _global_ void add(int *a, int *b, int *c); { *c = *a + *b; } int main() { int a, b, c;            //host copies of a, b ,c

    int *d_a, *d_b, *d_c;    //device copies of a, b, c

    int size = sizeof(int); //Allocate space for device copies of a, b, c

    cudaMalloc((void **)&d_a, size); cudaMalloc((void **)&d_b, size); cudaMalloc((void **)&d_c, size); //Setup input values

    a = 2; b = 7; //Cope inputs to device

 cudaMemcpy(d_a, &a, size, cudaMemcpyHostToDevice); cudaMemcpy(d_b, &b, size, cudaMemcpyHostToDevice); //Launch add() kernel on GPU 

    add<<<1,1>>>(d_a, d_b, d_c); //Copy result back to host

    cudaMemcpy(&c, d_c, size, cudaMemcpyDeviceToHost); //Cleanup

 cudaFree(d_a); cudaFree(d_b); cudaFree(d_c); return 0; }