character
chebyshev ripple	db (<0.0)
qfactor (resonator)	(>0.0)
frequency	Alpha Low Alpha Up or samplerate: Hz Lower corner Hz Midi note (69=A440) Upper corner Hz Midi note (69=A440)
more	matched z-transform (better off, check frequency response) prewarp (better on)
output	Signal bits (including sign): -1 bit saturation save brutal shift, this will remove shifts up to 4 positions by changing the factor, hence reducing accuracy by maximum 4 bits but more efficient calculation
execution


//Band pass resonator order=1 alpha1=0.01 
class filter
{
	public:
		filter()
		{
			for(int i=0; i <= 2; i++)
				v[i]=0;
		}
	private:
		short v[3];
	public:
		short step(short x)
		{
			v[0] = v[1];
			v[1] = v[2];
			long tmp = ((((x *  31928L) >>  6)	//= (   3.0449316288e-2 * x)
				+ (v[0] * -15386L)	//+( -0.9391013674*v[0])
				+ (v[1] * 31708L)	//+(  1.9352749938*v[1])
				)+8192) >> 14; // round and downshift fixed point /16384

			v[2]= (short)tmp;
			return (short)((
				 (v[2] - v[0]))); // 2^
		}
};