/* Single-element delay in a single filter.  The work function pushes
 * the item it received on the previous iteration, and then saves
 * the input item for the next iteration.
 */
float->float filter DelayOne {
    float last;
    init { 
        last = 0.0; 
    }
    work pop 1 push 1 { 
        push(last); 
	last = pop(); 
    }
}
// this generates the delays in the lattice structure
float->float splitjoin LatDel {
    split duplicate;
    add Identity<float>();
    add DelayOne();
    join roundrobin;
}

// this is the intermediate stage of the lattice filter
float->float filter LatFilt(float k_par) {
    work pop 2 peek 2 push 2 {
	float e_i = 0;
	float e_bar_i = 0;
	e_i = peek(0) - k_par*peek(1);
	e_bar_i = peek(1) - k_par*peek(0);
	push(e_i);
	push(e_bar_i);
	pop();
	pop();
    }
}

//this stage is the first stage of a lattice filter
float->float splitjoin ZeroStage {
    split duplicate;
    add Identity<float>();
    add Identity<float>();
    join roundrobin;
}

// this class combines the delaying phase and coefficients
float->float pipeline CompStage(float k_par) {
    add LatDel();
    add LatFilt(k_par);
}

// this class is the last stage of a lattice filter
float->void filter LastStage {
    work pop 2 {
	println(pop());
	pop();
    }
}

void->float filter Counter {
    float i;
    init {
	i = 1;
    }

    work push 1 {
	push(i);
	i = 0;
    }
}

void->void pipeline Lattice {
    add Counter();
    add ZeroStage();
    for (int i = 2; i < 10; i++) add CompStage(i);
    add LastStage();
}