/* Line function */
public static FP12 Line(ECP2 A, ECP2 B, FP Qx, FP Qy)
{
//System.out.println("Into line");
FP4 a, b, c; // Edits here
// c=new FP4(0);
if (A == B)
{
// Doubling
FP2 XX = new FP2(A.GetX()); //X
FP2 YY = new FP2(A.GetY()); //Y
FP2 ZZ = new FP2(A.GetZ()); //Z
FP2 YZ = new FP2(YY); //Y
YZ.Mul(ZZ); //YZ
XX.Sqr(); //X^2
YY.Sqr(); //Y^2
ZZ.Sqr(); //Z^2
YZ.IMul(4);
YZ.Neg();
YZ.Norm(); //-2YZ
YZ.PMul(Qy); //-2YZ.Ys
XX.IMul(6); //3X^2
XX.PMul(Qx); //3X^2.Xs
int sb = 3 * ROM.CURVE_B_I;
ZZ.IMul(sb);
if (ECP.SEXTIC_TWIST == ECP.D_TYPE)
{
ZZ.Div_Ip2();
}
if (ECP.SEXTIC_TWIST == ECP.M_TYPE)
{
ZZ.Mul_Ip();
ZZ.Add(ZZ);
YZ.Mul_Ip();
YZ.Norm();
}
ZZ.Norm(); // 3b.Z^2
YY.Add(YY);
ZZ.Sub(YY);
ZZ.Norm(); // 3b.Z^2-Y^2
a = new FP4(YZ, ZZ); // -2YZ.Ys | 3b.Z^2-Y^2 | 3X^2.Xs
if (ECP.SEXTIC_TWIST == ECP.D_TYPE)
{
b = new FP4(XX); // L(0,1) | L(0,0) | L(1,0)
c = new FP4(0);
}
if (ECP.SEXTIC_TWIST == ECP.M_TYPE)
{
b = new FP4(0);
c = new FP4(XX);
c.Times_I();
}
A.Dbl();
}
else
{
// Addition - assume B is affine
FP2 X1 = new FP2(A.GetX()); // X1
FP2 Y1 = new FP2(A.GetY()); // Y1
FP2 T1 = new FP2(A.GetZ()); // Z1
FP2 T2 = new FP2(A.GetZ()); // Z1
T1.Mul(B.GetY()); // T1=Z1.Y2
T2.Mul(B.GetX()); // T2=Z1.X2
X1.Sub(T2);
X1.Norm(); // X1=X1-Z1.X2
Y1.Sub(T1);
Y1.Norm(); // Y1=Y1-Z1.Y2
T1.Copy(X1); // T1=X1-Z1.X2
X1.PMul(Qy); // X1=(X1-Z1.X2).Ys
if (ECP.SEXTIC_TWIST == ECP.M_TYPE)
{
X1.Mul_Ip();
X1.Norm();
}
T1.Mul(B.GetY()); // T1=(X1-Z1.X2).Y2
T2.Copy(Y1); // T2=Y1-Z1.Y2
T2.Mul(B.GetX()); // T2=(Y1-Z1.Y2).X2
T2.Sub(T1);
T2.Norm(); // T2=(Y1-Z1.Y2).X2 - (X1-Z1.X2).Y2
Y1.PMul(Qx);
Y1.Neg();
Y1.Norm(); // Y1=-(Y1-Z1.Y2).Xs
a = new FP4(X1, T2); // (X1-Z1.X2).Ys | (Y1-Z1.Y2).X2 - (X1-Z1.X2).Y2 | - (Y1-Z1.Y2).Xs
if (ECP.SEXTIC_TWIST == ECP.D_TYPE)
{
b = new FP4(Y1);
c = new FP4(0);
}
if (ECP.SEXTIC_TWIST == ECP.M_TYPE)
{
b = new FP4(0);
c = new FP4(Y1);
c.Times_I();
}
A.Add(B);
}
//System.out.println("Out of line");
return(new FP12(a, b, c));
}