BIT_SET
#define BIT_SET(a, b) ((a)[(b)/BITS_PER_INT] |= (1 << ((b) % BITS_PER_INT)))
#define BIT_SET(a,n) ((a)[(n)>>SHIFT_WORD] |= (1L << ((n) & 31)))
#define BIT_SET(X,n) ((X) |= 1 << (n))