/* this+=this */
public int dbl()
{
if (INF)
{
return(-1);
}
if (y.iszilch())
{
inf();
return(-1);
}
FP2 w1 = new FP2(x);
FP2 w2 = new FP2(0);
FP2 w3 = new FP2(x);
FP2 w8 = new FP2(x);
w1.sqr();
w8.copy(w1);
w8.imul(3);
w2.copy(y);
w2.sqr();
w3.copy(x);
w3.mul(w2);
w3.imul(4);
w1.copy(w3);
w1.neg();
// w1.norm();
x.copy(w8);
x.sqr();
x.add(w1);
x.add(w1);
x.norm();
z.mul(y);
z.add(z);
w2.add(w2);
w2.sqr();
w2.add(w2);
w3.sub(x);
y.copy(w8);
y.mul(w3);
// w2.norm();
y.sub(w2);
y.norm();
z.norm();
return(1);
}
/* this+=Q - return 0 for add, 1 for double, -1 for O */
public int add(ECP2 Q)
{
if (INF)
{
copy(Q);
return(-1);
}
if (Q.INF)
{
return(-1);
}
bool aff = false;
if (Q.z.isunity())
{
aff = true;
}
FP2 A, C;
FP2 B = new FP2(z);
FP2 D = new FP2(z);
if (!aff)
{
A = new FP2(Q.z);
C = new FP2(Q.z);
A.sqr();
B.sqr();
C.mul(A);
D.mul(B);
A.mul(x);
C.mul(y);
}
else
{
A = new FP2(x);
C = new FP2(y);
B.sqr();
D.mul(B);
}
B.mul(Q.x);
B.sub(A);
D.mul(Q.y);
D.sub(C);
if (B.iszilch())
{
if (D.iszilch())
{
dbl();
return(1);
}
else
{
INF = true;
return(-1);
}
}
if (!aff)
{
z.mul(Q.z);
}
z.mul(B);
FP2 e = new FP2(B);
e.sqr();
B.mul(e);
A.mul(e);
e.copy(A);
e.add(A);
e.add(B);
x.copy(D);
x.sqr();
x.sub(e);
A.sub(x);
y.copy(A);
y.mul(D);
C.mul(B);
y.sub(C);
x.norm();
y.norm();
z.norm();
return(0);
}
/* test this==0 ? */
public bool iszilch()
{
reduce();
return(a.iszilch() && b.iszilch());
}
