samer@0: /*
samer@0:  *	Copyright (c) 2000, Samer Abdallah, King's College London.
samer@0:  *	All rights reserved.
samer@0:  *
samer@0:  *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
samer@0:  *	without even the implied warranty of MERCHANTABILITY or 
samer@0:  *	FITNESS FOR A PARTICULAR PURPOSE.
samer@0:  */
samer@0: 
samer@0: package samer.units;
samer@0: import samer.core.*;
samer@0: import samer.core.types.*;
samer@0: import samer.tools.*;
samer@0: import samer.maths.*;
samer@0: import java.util.*;
samer@0: 
samer@0: /**
samer@0: 	Temporally smoothed thresholding latch
samer@0:   */
samer@0: 
samer@0: public class Latch extends NamedTask
samer@0: {
samer@0: 	VDouble	thresh;
samer@0: 	VInteger	countThresh;
samer@0: 	boolean	[] states;
samer@0: 	int		[] counts;
samer@0: 	VVector	output;
samer@0: 	double[]	in,out;
samer@0: 	int		n;
samer@0: 		
samer@0: 	public Latch(VVector input) 
samer@0: 	{
samer@0: 		super("latch");
samer@0: 		n = input.size();
samer@0: 		states = new boolean[n];
samer@0: 		counts = new int[n];
samer@0: 		Shell.push(node);
samer@0: 		thresh = new VDouble("thresh",0.5);
samer@0: 		countThresh = new VInteger("count_thresh",3);
samer@0: 		output = new VVector("output", n);
samer@0: 		Shell.pop();
samer@0: 
samer@0: 		in=input.array();
samer@0: 		out=output.array();
samer@0: 	}
samer@0: 
samer@0: 	public VVector output() { return output; }
samer@0: 
samer@0: 	public void run()
samer@0: 	{
samer@0: 		for (int i=0; i<n; i++) {
samer@0: 
samer@0: 			if (!states[i]) {
samer@0: 
samer@0: 				// unit is off - check to see if it should be on
samer@0: 				if (in[i]>thresh.value) {
samer@0: 					if (++counts[i] >= countThresh.value) {
samer@0: 						out[i]=in[i];
samer@0: 						states[i]=true;
samer@0: 						counts[i]=0;
samer@0: 					}
samer@0: 				} else counts[i]=0;
samer@0: 
samer@0: 			} else {
samer@0: 
samer@0: 				// note is on - see about switching it off
samer@0: 				if (in[i]<=0.8*thresh.value) {
samer@0: 					if (++counts[i] >= countThresh.value) {
samer@0: 						out[i]=-1;
samer@0: 						states[i]=false;
samer@0: 						counts[i]=0;
samer@0: 					} else out[i]=in[i];
samer@0: 				} else {
samer@0: 					counts[i]=0;
samer@0: 					out[i]=in[i];
samer@0: 				}
samer@0: 			}
samer@0: 		}
samer@0: 		output.changed();
samer@0: 	}
samer@0: }