struct BlitDrawLineSetup {
  int dx, dy;
  int sud, sul, aul, accumulator, sign;
  int bltapt;
  int bltamod;
  int bltbmod;
  unsigned char *target;
};

void BlitDrawLine(
  struct ScreenSetup *screenSetup,
  struct BlitDrawLineSetup *setup,
  uint16_t sx,
  uint16_t sy,
  uint16_t ex,
  uint16_t ey,
  uint8_t color
) {
  unsigned char *target = screenSetup->memoryStart + (((screenSetup->width * sy + sx) >> 3) & 0xfffe);
  int i;

  setup->dx = ex - sx;
  setup->dy = ey - sy;

  if (setup->dx == 0 && setup->dy == 0) return;

  setup->sud = abs(setup->dy) < abs(setup->dx);
  if (!setup->sud) { i = setup->dx; setup->dx = setup->dy; setup->dy = i; }

  setup->sul = setup->dy < 0;
  setup->dy = abs(setup->dy);

  setup->aul = setup->dx < 0;
  setup->dx = abs(setup->dx);

  setup->accumulator = 4 * setup->dy - 2 * setup->dx;
  setup->sign = setup->accumulator < 0;

  for (i = 0; i < screenSetup->bitplanes; ++i) {
    custom.bltadat = 0x8000;
    custom.bltbdat = color & 1 == 1 ? 0xffff : 0;

    custom.bltafwm = 0xffff;
    custom.bltalwm = 0xffff;

    custom.bltamod = 4 * (setup->dy - setup->dx);
    custom.bltbmod = 4 * setup->dy;
    custom.bltcmod = screenSetup->width / 8;
    custom.bltdmod = screenSetup->width / 8;

    custom.bltapt = setup->accumulator;
    custom.bltcpt = target + screenSetup->nextBitplaneAdvance * i;
    custom.bltdpt = target + screenSetup->nextBitplaneAdvance * i;

    custom.bltcon0 = ((sx % 16) << 12) + (11 << 8) + 0xca;
    custom.bltcon1 = 1 + (setup->aul << 2) + (setup->sul << 3) + (setup->sud << 4) + (setup->sign << 6);

    custom.bltsize = 0x02 + ((setup->dx + 1) << 6);
    WaitBlit();

    color >>= 1;
  }
}