static int tile_offs_x = 0;
static int tile_offs_y = 0;
void sdDrawTiles(int layer, int row_begin, int row_end) {
    const int tile_stride = TILE_SIZE * TILE_SIZE;

    if (row_end == 0) {
        row_end = image_height;
    }

    int* tile_map = sdGetTileIndices(layer);
    const int COLS = tiled_width;
    const int ROWS = tiled_height;
    for (int y = row_begin; y < row_end; ++y) {
        for (int x = 0; x < image_width; ++x) {
            int tilex = ((x + tile_offs_x) & 0b111);
            int tiley = ((y + tile_offs_y) & 0b111);
            int cellx = ((x + tile_offs_x) >> 3) & 0b111111;
            int celly = ((y + tile_offs_y) >> 3) & 0b111111;
            int cellid = cellx + celly * tiled_width;
            int index = tile_map[cellid];

            uint32_t* psrc = &tile_data[index * tile_stride];
            uint32_t src = psrc[tilex + tiley * TILE_SIZE];
            uint32_t* dst = &backbuffer[x + y * image_width];
            (src & 0xFF000000) ? *dst = src : 0;
            //*dst = color32Mix(*dst, src);
            //backbuffer[x + y * client_width] = src;
        }
    }
}