COUNTER_BITS
index_recv = recv / COUNTER_BITS;
index_ctr = ctr->c_recv / COUNTER_BITS;
bit = 1ul << (recv % COUNTER_BITS);
#define COUNTER_NUM (COUNTER_BITS_TOTAL / COUNTER_BITS)
#define COUNTER_WINDOW_SIZE (COUNTER_BITS_TOTAL - COUNTER_BITS)