cuda矩阵练习（一）

一、定义矩阵结构

typedef struct
{
    int width;
    int height;
    float* elements;
}Matrix;

二、矩阵赋值

void magten(Matrix &t)
{
    for (int i = 0; i < t.width; i++)
    {
        for (int j = 0; j < t.height; j++)
        {
            t.elements[i*t.width + j] = rand() / BLOCK_SIZE + rand() / (BLOCK_SIZE*BLOCK_SIZE);
        }
    }
}

三、Device上执行矩阵计算

__global__ static void Mulikernel(const Matrix a, const Matrix b, Matrix c)
{
    int row = blockDim.y*blockIdx.y + threadIdx.y;
    int col = blockDim.x*blockIdx.x + threadIdx.x;
    float sum = 0;
    for (int i = 0; i < a.width; i++)
    {
        sum += a.elements[row*a.width + i] * b.elements[i*a.width + col];
    }
    c.elements[c.width*row + col] = sum;
}

四、申明变量分配空间，数据传输

void Mul(Matrix &a, Matrix &b, Matrix &c)
{
    Matrix d_a, d_b, d_c;
    d_a.width = a.width;
    d_a.height = a.height;
    size_t size = a.width*a.height*sizeof(float);
    cudaMalloc(&d_a.elements, size);

    d_b.width = b.width;
    d_b.height = b.height;
    size = b.width*b.height * sizeof(float);
    cudaMalloc(&d_b.elements, size);

    d_c.width =c.width;
    d_c.height = c.height;
     size = c.width*c.height * sizeof(float);
    cudaMalloc(&d_c.elements, size);

    magten(a);
    magten(b);
    //magten(c);

    cudaMemcpy(d_a.elements, a.elements, size, cudaMemcpyHostToDevice);
    cudaMemcpy(d_b.elements, b.elements, size, cudaMemcpyHostToDevice);
    //cudaMemcpy(&d_a, &a, size, cudaMemcpyHostToDevice);

    //Mulikernel << <BLOCK_SIZE, BLOCK_SIZE >> > (d_a, d_b, d_c);
    dim3 dimBlock(BLOCK_SIZE, BLOCK_SIZE);
    dim3 dimGrid(b.width / dimBlock.x, a.height / dimBlock.y);
    Mulikernel<< <dimGrid, dimBlock >> >(d_a, d_b, d_c);

    cudaMemcpy(c.elements, d_c.elements, size, cudaMemcpyDeviceToHost);

    //printf
    printf("success!");
    cudaFree(&d_a);
    cudaFree(&d_b);
    cudaFree(&d_c);
    //return 0;
}

五、主函数

int main()
{
    Matrix a, b, c;
    
    a.width = 6;
    a.height = 8;
    b.width = 8;
    b.height = 8;
    a.elements=(float*)malloc( a.height*a.width * sizeof(float));
    b.elements = (float*)malloc(b.height*b.width * sizeof(float));
    Mul(a, b, c);
    return 0;
}

总结：程序分为这些部分，强调每一个程序必须有一个主函数，因为是程序入口地址，为变量分配好空间，不要遗漏任何一个变量