#define NUM_BYTES 16	
typedef unsigned char BigInt[NUM_BYTES];

/* Atribuicao */

/* res = val (extensao com sinal) */
void big_val (BigInt res, long val);

/* Operacoes aritmeticas */

/* res = -a */
void big_comp2(BigInt res, BigInt a);

/* res = a + b */
void big_sum (BigInt res, BigInt a, BigInt b);

/* res = a - b */
void big_sub (BigInt res, BigInt a, BigInt b);

/* res = a * b */
void big_mul (BigInt res, BigInt a, BigInt b);

/* Operacoes de deslocamento */

/* res = a << n */
void big_shl (BigInt res, BigInt a, int n);

/* res = a >> n (logico) */
void big_shr (BigInt res, BigInt a, int n);