// first order filter model 
// transfer function:
// G(s) = K / ( s * Tau + 1 )
// K is gain constant
// Tau is time constant
// 
// inp is input state variable

class Filter1st(inp, K, Tau) 
{
	var m_state = State( int ( (K * inp.value - m_state.value) / Tau ) );
};