arggg

for(int y = 0;y<h;++y) {
    const int yy = (y+b.y1)&7;
    const int xx = b.x1 + (y/8)*???; // fuck
    const size_t offs = ((y+b.y1)*width+(b.x1));
    uint8_t* const pbegin = m_frame_buffer+(offs/8);
    bits::set_bits(pbegin,offs%8,w,color);
}