FLOAT sqrt(FLOAT x) {
FLOAT dt, t = int2F(2);
do {
dt = F_div_int((F_div_F(x, t) - t), 2);
t += dt;
} while(Fabs(dt) > f2F(1e-4));
return t;
}
FLOAT pow(FLOAT x, FLOAT y) {
/* we only compute x^0.333 */
FLOAT t2, dt, t = int2F(2);
do {
t2 = F_mul_F(t, t);
dt = (F_div_F(x, t2) - t) / 3;
t += dt;
} while(Fabs(dt) > f2F(1e-4));
return t;
}
/* 在屏幕上创建一个新的字母 */
void
create_new_letter(void) {
if (head == NULL) {
head = fly_new(); /* 当前没有任何字母，创建新链表 */
} else {
fly_t now = fly_new();
fly_insert(NULL, head, now); /* 插入到链表的头部 */
head = now;
}
/* 字母、初始位置、掉落速度均为随机设定 */
head->x = 0;
head->y = rand() % (SCR_WIDTH / 8 - 2) * 8 + 8;
head->v = F_div_F(int2F(rand() % 1000), int2F(2000)) + f2F(0.5);
head->text = rand() % 26;
release_key(head->text); /* 清除过往的按键 */
}
FLOAT f(FLOAT x) {
return F_div_F(int2F(1),int2F(1) + F_mul_int(F_mul_F(x,x),25));
/* f(x) = 1/(1+25x^2) */
/* FLOAT a = int2F(1);
FLOAT b = F_mul_F(x,x);
FLOAT c = F_mul_int(b ,25);
FLOAT d = int2F(1) + c;*/
// nemu_assert(x == f2F(0.8));
// nemu_assert(b < f2F(0));
/*
a ++ ;
a -- ;
b ++ ;
b -- ;
c ++ ;
c -- ;
d ++ ;
d -- ;
return F_div_F(a,d);*/
}
FLOAT f(FLOAT x) {
/* f(x) = 1/(1+25x^2) */
return F_div_F(int2F(1), int2F(1) + F_mul_int(F_mul_F(x, x), 25));
}
