SS_WIDTH
#define SKIP_NEXT_LINE(addr) (addr) += (PS_WIDTH - SS_WIDTH)
for (j = 0; j < SS_WIDTH; j++)
for (j = 0; j < SS_WIDTH; j++) {
p += (PS_WIDTH - SS_WIDTH);
q += (PS_WIDTH - SS_WIDTH);
for (j = 0; j < SS_WIDTH; j++) {
q += (PS_WIDTH - SS_WIDTH);