cf
#define bset(arg, posn) ((arg) |= (1L << (posn)))
#define bclr(arg, posn) ((arg) &= ~(1L << (posn)))
#define btst(arg, posn) ((arg) & (1L << (posn)))
#define bflp(arg, posn) ((arg) ^= (1L << (posn)))
.

0