扩展欧几里得算法求乘法逆元

int ExtendedEuclid(int f, int d, int *result)//求f 模  d 的 逆元
{
    int x1, x2, x3, y1, y2, y3, t1, t2, t3, q;
    x1 = y2 = 1;
    x2 = y1 = 0;
    x3 = d;
    y3 = f;
    while (1)
    {
	if (y3 == 0)
	{
	    *result = x3; /* 两个数不互素则result为两个数的最大公约数，此时返回值为零 */
	    return 0;//无乘法逆元
	}
	if (y3 == 1)
	{
	    *result = y2; /* 两个数互素则resutl为其乘法逆元，此时返回值为1 */
	    return 1;
	}
	q = x3 / y3;
	t1 = x1 - q*y1;
	t2 = x2 - q*y2;
	t3 = x3 - q*y3;
	x1 = y1;
	x2 = y2;
	x3 = y3;
	y1 = t1;
	y2 = t2;
	y3 = t3;
    }

}