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


//Low pass bessel filter order=2 alpha1=0.06 
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 * 5342655L) >>  5)	//= (   3.9805879528e-2 * x)
				+ ((v[0] * -7243194L) >> 2)	//+( -0.4317280064*v[0])
				+ (v[1] * 5337271L)	//+(  1.2725044883*v[1])
				)+2097152) >> 22; // round and downshift fixed point /4194304

			v[2]= (short)tmp;
			return (short)((
				 (v[0] + v[2])
				+2 * v[1])); // 2^
		}
};