PS_WIDTH
#define NEXT_LINE(addr) ((addr) + (PS_WIDTH * FB_HEIGHT))
#define SKIP_NEXT_LINE(addr) (addr) += (PS_WIDTH - SS_WIDTH)
p += ((PS_WIDTH * FB_HEIGHT) * (ymin + 1));
q += ((PS_WIDTH * FB_HEIGHT) * ymin);
p += (PS_WIDTH - SS_WIDTH);
q += (PS_WIDTH - SS_WIDTH);
q += (PS_WIDTH - SS_WIDTH);