/* reduce this mod m */
public virtual void Mod(BIG m1)
{
int k = 0;
BIG r = new BIG(0);
BIG m = new BIG(m1);
Norm();
if (Comp(this, m) < 0)
{
return;
}
do
{
m.FShl(1);
k++;
} while (Comp(this, m) >= 0);
while (k > 0)
{
m.FShr(1);
r.Copy(this);
r.Sub(m);
r.Norm();
CMove(r, (int)(1 - ((r.w[NLEN - 1] >> (CHUNK - 1)) & 1)));
k--;
}
}
/* divide this by m */
public virtual void Div(BIG m1)
{
int d, k = 0;
Norm();
BIG e = new BIG(1);
BIG m = new BIG(m1);
BIG b = new BIG(this);
BIG r = new BIG(0);
Zero();
while (Comp(b, m) >= 0)
{
e.FShl(1);
m.FShl(1);
k++;
}
while (k > 0)
{
m.FShr(1);
e.FShr(1);
r.Copy(b);
r.Sub(m);
r.Norm();
d = (int)(1 - ((r.w[NLEN - 1] >> (CHUNK - 1)) & 1));
b.CMove(r, d);
r.Copy(this);
r.Add(e);
r.Norm();
CMove(r, d);
k--;
}
}
/* this=1/this mod p. Binary method */
public virtual void InvModp(BIG p)
{
Mod(p);
BIG u = new BIG(this);
BIG v = new BIG(p);
BIG x1 = new BIG(1);
BIG x2 = new BIG(0);
BIG t = new BIG(0);
BIG one = new BIG(1);
while (Comp(u, one) != 0 && Comp(v, one) != 0)
{
while (u.Parity() == 0)
{
u.FShr(1);
if (x1.Parity() != 0)
{
x1.Add(p);
x1.Norm();
}
x1.FShr(1);
}
while (v.Parity() == 0)
{
v.FShr(1);
if (x2.Parity() != 0)
{
x2.Add(p);
x2.Norm();
}
x2.FShr(1);
}
if (Comp(u, v) >= 0)
{
u.Sub(v);
u.Norm();
if (Comp(x1, x2) >= 0)
{
x1.Sub(x2);
}
else
{
t.Copy(p);
t.Sub(x2);
x1.Add(t);
}
x1.Norm();
}
else
{
v.Sub(u);
v.Norm();
if (Comp(x2, x1) >= 0)
{
x2.Sub(x1);
}
else
{
t.Copy(p);
t.Sub(x1);
x2.Add(t);
}
x2.Norm();
}
}
if (Comp(u, one) == 0)
{
Copy(x1);
}
else
{
Copy(x2);
}
}