optimize this Shifting code ?

In FFT one usually needs to shift/cycle the values in an array.
Typically the entries are shifted in the way:
012 345 to 345 012

The following code does this, but I wonder if there are possibilites to 
optimize it? It is very generall, but the shifting with the delimiter in 
the middle is the only one that I need.

// *********************************
// Cycle changes 012 345 to 345 012
// *********************************
void QFFTW::Cycle(complex<double> *A1,long N)
{
	Cycle(A1,N,N/2);
}


void QFFTW::Cycle(complex<double> *A1,long N,long del)
{
long i;
complex<double> *D;

	D=new complex<double>[N];

	if (del>=N) del-=N;
	if (del<=-N) del+=N;

	if(del>0 && del<N)
	{
		for (i=N-del;i<N;i++)	D[i-N+del]=A1[i];
		for (i=N-1;i>=del;i--) A1[i]=A1[i-del];
		for (i=0;i<del;i++)	A1[i]=D[i];
	}
	else if(del<0	&&	del > -N)
	{
		del=-del;
		for (i=0;i<del;i++)	D[i]=A1[i];
		for (i=0;i<N-del;i++) A1[i]=A1[i+del];
		for (i=N-del;i<N;i++) A1[i]=D[i-N+del];
	}
	delete [] D;
}