void num_to_bytes(uint64_t n, size_t len, uint8_t* dest);
uint64_t bytes_to_num(uint8_t* src, size_t len);
void num_to_bytebits(uint64_t n, size_t len, uint8_t *dest);
void num_to_bytes(uint64_t n, size_t len, uint8_t* dest);
uint64_t bytes_to_num(uint8_t* src, size_t len);
void num_to_bytebits(uint64_t n, size_t len, uint8_t *dest);