 
         and_reduction_1D<<<1, block_dim.x * block_dim.y, block_dim.x * block_dim.y * sizeof(uint8_t)>>>(d_block_equ, d_grid_equ, block_equ_size);
 
-        // ================
-
         // bring d_grid_equ back from device
         cudaMemcpy(&grid_equ, d_grid_equ, grid_equ_size, cudaMemcpyDeviceToHost);
 

    // allocate memory on device
    uint8_t* d_src_data = NULL;
    uint8_t* d_dst_data = NULL;
    // uint8_t* d_pixel_equ = NULL;
    uint8_t* d_block_equ = NULL;
    uint8_t* d_grid_equ = NULL;

    unsigned int data_size = (*src_bitmap)->width * (*src_bitmap)->height * sizeof(uint8_t);
    // unsigned int pixel_equ_size = ((*src_bitmap)->width - padding.left - padding.right) * ((*src_bitmap)->height - padding.top - padding.bottom) * sizeof(uint8_t);
    unsigned int block_equ_size = grid_dim.x * grid_dim.y * sizeof(uint8_t);
    unsigned int grid_equ_size = 1 * sizeof(uint8_t);

    cudaError d_src_malloc_success = cudaMalloc((void**) &d_src_data, data_size);
    cudaError d_dst_malloc_success = cudaMalloc((void**) &d_dst_data, data_size);
    // cudaError d_pixel_equ_malloc_success = cudaMalloc((void**) &d_pixel_equ, pixel_equ_size);
    cudaError d_block_equ_malloc_success = cudaMalloc((void**) &d_block_equ, block_equ_size);
    cudaError d_grid_equ_malloc_success = cudaMalloc((void**) &d_grid_equ, grid_equ_size);

    assert((d_src_malloc_success == cudaSuccess) && "Error: could not allocate memory for d_src_data");
    assert((d_dst_malloc_success == cudaSuccess) && "Error: could not allocate memory for d_dst_data");
    // assert((d_pixel_equ_malloc_success == cudaSuccess) && "Error: could not allocate memory for d_pixel_equ");
    assert((d_block_equ_malloc_success == cudaSuccess) && "Error: could not allocate memory for d_block_equ");
    assert((d_grid_equ_malloc_success == cudaSuccess) && "Error: could not allocate memory for d_grid_equ");


        // pixel_equality<<<grid_dim, block_dim>>>(d_src_data, d_dst_data, d_pixel_equ, (*src_bitmap)->width, padding);

        // 1D grid & 1D block reduction

        // First reduction from d_src_data and d_dst_data to d_block_equ
        and_reduction_2D<<<grid_dim, block_dim, block_dim.x * block_dim.y * sizeof(uint8_t)>>>(d_src_data, d_dst_data, d_block_equ, (*src_bitmap)->width, data_size, padding);
