Plurk paste

__global__ void matMultiply(float *Ad, float *Bd, float *AxBd, int SIZE, int iter){
        //SIZE 是矩陣的維度
        int i = threadIdx.y + blockIdx.y*TILE_W;
        int j = threadIdx.x + blockIdx.x*TILE_W;
        int k;
        float AxB_ij;

        if(iter == 0){
                for(k=0; k<SIZE; k++){
                        AxB_ij += Ad[i*SIZE + k] * Bd[k*SIZE +j];
                }
                AxBd[i*SIZE +j] = AxB_ij;
        }

        // iter!=0 是矩陣太大時,每個block要跑多個tile用的
        else {
                while (i<SIZE){
                        while (j<SIZE){
                                AxB_ij = 0;
                                for(k=0; k<SIZE; k++){
                                        AxB_ij += Ad[i*SIZE+k] * Bd[k*SIZE+j];
                                }
                                AxBd[i*SIZE +j] = AxB_ij;
                                // j counter 的進位
                                j += blockDim.x * gridDim.x;
                        }
                        // i counter 的進位, j counter 回到本來的 threadIdx.x +blockIdx.x*TILE_W
                        i += blockDim.y * gridDim.y;
                        j = threadIdx.x + blockIdx.x*TILE_W;
                }
        }
}