auto VDC::Background::scanline(uint y) -> void {
}

auto VDC::Background::run(uint x, uint y) -> void {
  color = nothing;
//if(blank) return;

  uint10 hoffset = x + hscroll;
  uint9  voffset = y + vscroll;

  uint16 batAddress = (voffset >> 3) * width + (hoffset >> 3);
  uint16 tiledata = vdc.vramRead(batAddress);
  uint16 patternAddress = tiledata.bits(0,11) << 4;
  patternAddress += (voffset & 7);
  uint4 palette = tiledata.bits(12,15);

  uint16 d0 = vdc.vramRead(patternAddress + 0);
  uint16 d1 = vdc.vramRead(patternAddress + 8);

  uint3 index = 7 - (hoffset & 7);
  uint4 output;
  output.bit(0) = d0.bit(0 + index);
  output.bit(1) = d0.bit(8 + index);
  output.bit(2) = d1.bit(0 + index);
  output.bit(3) = d1.bit(8 + index);

  if(output == 0) return;
  color = vdc.cram[palette << 4 | output];
}