/* this*=c mod Modulus, where c is a small int */
public void imul(int c)
{
norm();
bool s = false;
if (c < 0)
{
c = -c;
s = true;
}
long afx = (BIG.EXCESS(x) + 1) * (c + 1) + 1;
if (c < ROM.NEXCESS && afx < ROM.FEXCESS)
{
x.imul(c);
}
else
{
if (afx < ROM.FEXCESS)
{
x.pmul(c);
}
else
{
DBIG d = x.pxmul(c);
x.copy(d.mod(p));
}
}
if (s)
{
neg();
}
norm();
}
/* this+=b */
public void add(FP b)
{
x.add(b.x);
if (BIG.EXCESS(x) + 2 >= ROM.FEXCESS)
{
reduce();
}
}
/* this*=this mod Modulus */
public void sqr()
{
DBIG d;
long ea = BIG.EXCESS(x);
if ((ea + 1) * (ea + 1) + 1 >= ROM.FEXCESS)
{
reduce();
}
d = BIG.sqr(x);
x.copy(BIG.mod(d));
}
/* this*=b mod Modulus */
public void mul(FP b)
{
long ea = BIG.EXCESS(x);
long eb = BIG.EXCESS(b.x);
if ((ea + 1) * (eb + 1) + 1 >= ROM.FEXCESS)
{
reduce();
}
DBIG d = BIG.mul(x, b.x);
x.copy(BIG.mod(d));
}
/* this = -this mod Modulus */
public void neg()
{
int sb;
long ov;
BIG m = new BIG(p);
norm();
ov = BIG.EXCESS(x);
sb = 1;
while (ov != 0)
{
sb++;
ov >>= 1;
}
m.fshl(sb);
x.rsub(m);
if (BIG.EXCESS(x) >= ROM.FEXCESS)
{
reduce();
}
}
