DecodeSim.java

package com.example.scrap;

import java.util.ArrayList;
import java.util.stream.Collectors;

import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.PeekingIterator;

public class DecodeSim {
	
	private static int MAX_BYTES = 16;
	private static int MAX_INS = 4;
	private static boolean VERBOSE = false;
	
	// various patterns
	private static final Iterable<Integer> MONOID_PATTERN = Iterables.cycle(3,3,3,3,4,5,5,6);
	
	ArrayList<Integer> decodeOne(PeekingIterator<Integer> sizeStream) {
		int bytes = 0;
		ArrayList<Integer> decoded = new ArrayList<>(5);
		while (sizeStream.hasNext()) {
			int next = sizeStream.peek();
			if ((bytes + next) > MAX_BYTES || decoded.size() >= MAX_INS) {
				break;
			}
			bytes += next;
			decoded.add(sizeStream.next());
		};
		
		if (VERBOSE) {
			System.out.println("Decoded " + decoded.size() + " instructions using " + bytes + " bytes: "
					+ decoded);
		}
		
		return decoded;
	}
	
	
	
	void decodeMany(Iterable<Integer> sizes) {
		int cycles = 0, instructions = 0, bytes = 0;
		PeekingIterator<Integer> itr = Iterators.peekingIterator(sizes.iterator());
		System.out.println(String.format("%8s%12s%12s%12s", "cycles", "IPC", "bytes/cycle", "decoded"));
		while (itr.hasNext()) {
			ArrayList<Integer> result = decodeOne(itr);
			instructions += result.size();
			bytes += result.stream().mapToInt(Integer::intValue).sum();
			cycles++;
			System.out.println(String.format("%8d%12.3f%12.3f%12s", cycles,
					(double)instructions/cycles, (double)bytes/cycles, packedStr(result)));
		}
	}
	
	private Object packedStr(ArrayList<Integer> a) {
		return a.stream().map(i -> i.toString()).collect(Collectors.joining());
	}


	public static void main(String[] args) {
		DecodeSim sim = new DecodeSim();
//		Iterable<Integer> ALL4 = Iterables.cycle(4);
		sim.decodeMany(Iterables.limit(MONOID_PATTERN, 1000));
	}

}