/// <summary>
/// Xor function for FDD's, same as a != differ function.
/// </summary>
/// <param name="u1">left side of the expression</param>
/// <param name="u2">right side of the expression</param>
/// <returns>a new BDD where u1 and u2 are xor'ed</returns>
public static Bdd Xor(Fdd u1, Fdd u2)
{
int u1Size = Size(u1);
int u2Size = Size(u2);
int MinSize = Min(u1Size, u2Size);
Bdd result = new Bdd(false);
for (int i = 0; i < MinSize; i++)
{
result = Kernel.Or(result, Kernel.Xor(new Bdd(u1.Var + i), new Bdd(u2.Var + i)));
}
if (u1Size != u2Size)
{
if (u1Size > u2Size) //you reach this state when 2 Fdds does not have the same number
{ //of bits. What happens is then the smallest get buffered with 0's
for (int i = MinSize; i < u1Size; i++)
{
result = Kernel.Or(result, Kernel.Xor(new Bdd(u1.Var + i), new Bdd(false)));
}
}
else
{
for (int i = MinSize; i < u2Size; i++)
{
result = Kernel.Or(result, Kernel.Xor(new Bdd(false), new Bdd(u2.Var + i)));
}
}
}
return(result);
}
public Bdd execute()
{
// Calls specific methods from Kernel
Bdd l = left.execute();
Bdd r = right.execute();
Bdd result = new Bdd(false);
switch (op)
{
case Kind.DIS:
result = BDD.Or(l, r);
break;
case Kind.CON:
result = BDD.And(l, r);
break;
case Kind.BIMP:
result = BDD.Equal(l, r);
break;
case Kind.NAND:
result = BDD.Nand(l, r);
break;
case Kind.XOR:
result = BDD.Xor(l, r);
break;
case Kind.NOR:
result = BDD.Nor(l, r);
break;
case Kind.NOT:
result = BDD.Not(r);
break;
}
l.Dispose(); //forced garbage collection
r.Dispose();
return(result);
}
/// <summary>
/// Not equal operator on two Bdds
/// </summary>
/// <param name="l">Left Bdd</param>
/// <param name="r">Right Bdd</param>
/// <returns>Resulting Bdd</returns>
public static Bdd operator !=(Bdd l, Bdd r)
{
return(Kernel.Xor(l, r));
}
