BITS_PER_MAP
#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
j = bit / BITS_PER_MAP;
bit = bit & ~(BITS_PER_MAP - 1);
for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
for (mask = 0x1, i = 0; i < BITS_PER_MAP; i++) {
#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
for (i = 0; i < BITS_PER_MAP; i++) {
j = bit / BITS_PER_MAP;
bit = rounddown2(bit, BITS_PER_MAP);
for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)